TECHNICAL FIELD
[0001] The present invention relates to a screw compressor.
BACKGROUND ART
[0002] As a conventional compressor for compressing a fluid such as a refrigerant or air,
a screw compressor having a first rotor comprised of a screw rotor provided with helical
grooves, and second rotors which mesh with the first rotor and rotate together with
the first rotor has been used (see Patent document 1 below).
[0003] Patent Document 1 discloses a single-screw compressor including a screw rotor as
a first rotor which is rotatably housed in a cylindrical wall, and gate rotors as
second rotors which are arranged outside the cylindrical wall. Some of gates of each
gate rotor enter the internal space of the cylindrical wall through an opening formed
therein to mesh with the screw rotor, so that the gate rotors rotate together with
the screw rotor. The cylindrical wall, the screw rotor, and the gates meshing with
the screw rotor define a compression chamber in the helical grooves. When the screw
rotor is driven by an electric motor to rotate, the gates meshing with the screw rotor
are pushed to rotate the two gate rotors. When the position of the gate changes in
the helical groove, the capacity of the compression chamber decreases to compress
the fluid.
[0004] In the conventional screw compressor described above, a lubricant is injected toward
the screw rotor from an oil supply port formed at a predetermined position of the
cylindrical wall to supply the lubricant between sliding surfaces of two members,
such as the screw rotor and the gate, or the screw rotor and the cylindrical wall,
thereby lubricating the sliding surfaces, or sealing a minute gap, if any, formed
between the two members when they do not slide. This configuration keeps the sliding
surfaces of the screw compressor from wearing or seizing, and blocks a high pressure
fluid from leaking from the compression chamber defined by the cylindrical wall, the
screw rotor, and the gate.
CITATION LIST
PATENT DOCUMENT
[0005] [Patent Document 1] Japanese Published Patent Application No.
2009-197794
SUMMARY OF THE INVENTION
TECHNICAL PROBLEM
[0006] When the lubricant is injected toward the screw rotor from the oil supply port formed
at a predetermined position of the cylindrical wall, just like in the screw compressor
described above, the lubricant does not reach the sliding surfaces in some cases when
the injection amount of the lubricant is small. Therefore, the screw compressor described
above requires the injection of a large amount of lubricant in order to supply the
lubricant to the sliding surfaces with reliability.
[0007] However, when a large amount of lubricant is injected into the helical grooves of
the screw rotor, the lubricant can be reliably supplied to the sliding surfaces, but
power required for transporting the lubricant increases. Further, when a large amount
of lubricant is supplied into the helical grooves of the screw rotor, an excess of
the lubricant blocks the screw rotor from rotating, which increases power required
for the rotation of the screw rotor. When the screw compressor is improved in speed
and reduced in size, such an increase in the required power has been a problem because
the efficiency of the compressor remarkably decreases.
[0008] In view of the foregoing, it is therefore an object of the present invention to provide
a configuration of a screw compressor in which the lubricant can be reliably supplied
to the sliding surfaces while reducing the supply amount of the lubricant.
SOLUTION TO THE PROBLEM
[0009] A first aspect of the present disclosure is directed to a screw compressor comprising:
a first rotor (40) provided with a helical groove (41); a second rotor (50) which
meshes with the first rotor (40) and rotates together with the first rotor (40); a
rotor casing (30) which covers at least an outer periphery of the first rotor (40),
and defines a compression chamber (23) in the helical groove (41) together with the
first rotor (40) and the second rotor (50), wherein a fluid is compressed in the compression
chamber (23), and at least one of the first rotor (40) or the second rotor (50) is
provided with an oil supply passage (5) which is connected to an oil supply port (4)
opened at a sliding surface (3) of the rotor (40, 50) to supply a lubricant to the
sliding surface (3).
[0010] In the first aspect of the present disclosure, the oil supply passage (5) is formed
in at least one of the rotors (40, 50), i.e., the first rotor (40) and the second
rotor (50) which mesh with each other and rotate together, and the oil supply passage
(5) is connected to the oil supply port (4) opened at the sliding surface (3) of the
rotor (40, 50) in which the oil supply passage (5) is formed. Thus, in the rotor (40,
50) provided with the oil supply passage (5), the lubricant in the oil supply passage
(5) flows from the oil supply port (4) to the sliding surface (3) to lubricate the
sliding surface (3), or seal a gap, if any, between the sliding surface (3) and its
counterpart sliding surface.
[0011] Further, in the first aspect of the present disclosure, unlike the conventional configuration
in which the lubricant is injected from the oil supply port formed in a rotor casing
which does not rotate, the oil supply port (4) is opened at the sliding surface (3)
of the rotor (40, 50) that rotates, from which the lubricant is allowed to flow to
the sliding surface (3). Therefore, the lubricant flowing from the oil supply port
(4) is rapidly spread over the rotating rotor (40, 50), and is rapidly supplied to
the sliding surface (3) other than the sliding surface (3) at which the oil supply
port (4) is formed. Since the first rotor (40) and the second rotor (50) mesh with
each other and rotate together, the lubricant supplied to one of the rotors (40, 50)
provided with the oil supply passage (5) is rapidly spread to the other rotor (50,
40). Thus, the lubricant is quickly supplied to the sliding surface (3) of the other
rotor (50, 40).
[0012] A second aspect of the present disclosure is an embodiment of the first aspect. In
the second aspect, a switching mechanism (6) switches the oil supply passage (5) between
a supply state in which the lubricant is supplied to the sliding surface (3) and a
non-supply state in which no lubricant is supplied to the sliding surface (3).
[0013] In the second aspect of the present disclosure, the oil supply passage (5) can be
switched between the supply state in which the lubricant is supplied from the oil
supply passage (5) to the sliding surface (3), and the non-supply state in which no
lubricant is supplied from the oil supply passage (5) to the sliding surface (3).
[0014] A third aspect of the present disclosure is an embodiment of the second aspect. In
the third aspect, the switching mechanism (6) is configured to switch the oil supply
passage (5) to the supply state by causing an oil supply source (94c, 95c) for supplying
the lubricant to the oil supply passage (5) to communicate with the oil supply passage
(5) when a rotational angle position of the rotor (40, 50) provided with the oil supply
passage (5) is in a predetermined angular range, and to switch the oil supply passage
(5) to the non-supply state by blocking the oil supply source (94c, 95c) from the
oil supply passage (5) when the rotational angle position of the rotor (40, 50) is
out of the predetermined angular range.
[0015] In the third aspect of the present disclosure, when the rotational angle position
of the rotor (40, 50) provided with the oil supply passage (5) is in the predetermined
angle range, the oil supply source (94c, 95c) communicates with the oil supply passage
(5), and the oil supply passage (5) is switched to the supply state. When the rotational
angle position of the rotor (40, 50) is out of the predetermined angle range, the
oil supply source (94c, 95c) and the oil supply passage (5) are blocked from each
other, and the oil supply passage (5) is switched to the non-supply state.
[0016] A fourth aspect of the present disclosure is an embodiment of any one of the first
to third aspects. In the fourth aspect, the first rotor (40) is a screw rotor (40)
rotatably housed in a cylindrical wall (30) constituting the rotor casing (30), the
second rotor (50) is a gear-shaped gate rotor (50) having a plurality of flat gates
(51) and arranged outside the cylindrical wall (30), some of the gates (51) entering
a space inside the cylindrical wall (30) via an opening (39) formed in the cylindrical
wall (30) and meshing with the screw rotor (40) so that the gate rotor (50) rotates
together with the screw rotor (40), the oil supply passage (5) is formed in at least
one of the gates (51) of the gate rotor (50), and the oil supply port (4) is a lateral
oil supply port (63b) opened at a side surface (51a, 51b) of the at least one gate
(51), the side surface (51a, 51b) serving as the sliding surface (3) which slides
on the screw rotor (40).
[0017] In the fourth aspect of the present disclosure, the screw compressor (1) is configured
as a single-screw compressor (1), and the gate rotor (50) which meshes with the screw
rotor (40) rotates as the screw rotor (40) rotates. As a result, the position of the
gate (51) in the helical groove (41) of the screw rotor (40) changes, the capacity
of the compression chamber (23) gradually decreases, and the fluid is compressed.
At this time, the lubricant in the oil supply passage (5) formed in the gate (51)
of the gate rotor (50) flows from the lateral oil supply port (63b) opened at the
side surface (51a, 51b) of the gate (51) sliding on the screw rotor (40). Thus, the
lubricant is supplied between the side surface (51a, 51b) of the gate (51) and the
screw rotor (40), thereby lubricating these sliding surfaces (3), or sealing a gap,
if any, between these sliding surfaces (3). The lubricant supplied between the side
surface (51a, 51b) of the gate (51) and the screw rotor (40) adheres to the screw
rotor (40), and is spread toward the outer periphery of the screw rotor (40) by the
effect of a centrifugal force generated by the rotation of the screw rotor (40). Thus,
the lubricant is supplied to a gap between the screw rotor (40) and the cylindrical
wall (30) to seal the gap.
[0018] A fifth aspect of the present disclosure is an embodiment of the fourth aspect. In
the fifth aspect, the lateral oil supply port (63b) is opened at least at one of side
surfaces (51b), including the side surface (51a, 51b), on a rear side in a direction
of rotation of the at least one gate (51).
[0019] When the screw rotor (40) rotates, the lateral face of the helical groove (41) of
the screw rotor (40) pushes the gate (51) to rotate the gear-shaped gate rotor (50)
meshing with the screw rotor (40). Specifically, the side surface (51b) on the rear
side in the rotation direction of the gate (51) is the sliding surface which reliably
slides on the screw rotor (40) and is pushed by the screw rotor (40), and therefore,
is probably worn through the sliding movement.
[0020] In the fifth aspect of the present disclosure, the lubricant is directly supplied
to the rear side surface (51b) of the gate (51) in the rotation direction from the
oil supply passage (5). This makes it possible to reliably supply the lubricant to
the gap between the rear side surface (51b) of the gate (51) in the rotation direction,
which is probably worn through the sliding movement, and the lateral faces of the
helical groove (41) of the screw rotor (40), thereby lubricating the sliding surfaces
(3).
[0021] A sixth aspect of the present disclosure is an embodiment of the fourth or fifth
aspect. In the sixth aspect, the oil supply passage (5) is connected to a front oil
supply port (63c) opened at a front surface (51c) of the at least one gate (51) facing
the compression chamber (23).
[0022] The rotation of the gate rotor (50) causes the gate (51) to come in and out of the
space inside the cylindrical wall (30) via the opening (39). In general, a gap is
formed between the front surface (51c) of the gate (51) and the cylindrical wall (30),
but the front surface (51c) of the gate (51) may slide on the cylindrical wall (30)
when the gate rotor (50) thermally expands. If the gap is present between the front
surface (51c) of the gate (51) and the cylindrical wall (30), the lubricant may possibly
leak from the high pressure compression chamber (23) through the gap to a low-pressure
space outside the cylindrical wall (30) in which the gate rotor (50) is disposed.
Thus, the gap needs to be sealed.
[0023] In the sixth aspect of the present disclosure, the oil supply passage (5) is also
connected to the front oil supply port (63c) opened at the front surface (51c) of
the gate (51). Therefore, in the gate (51) of the gate rotor (50), the lubricant in
the oil supply passage (5) is supplied not only to the side surface (51a, 51b) that
slide on the screw rotor (40) but also to the front surface (51c) that faces the compression
chamber (23). Thus, the lubricant is supplied between the front surface (51c) of the
gate (51) and the cylindrical wall (30), thereby lubricating the front surface (51c)
and the cylindrical wall (30), or sealing a gap, if any, formed between the front
surface (51c) and the cylindrical wall (30).
[0024] A seventh aspect of the present disclosure is an embodiment of any one of the fourth
to sixth aspects. In the seventh aspect, the lateral oil supply port (63b) includes
at least one lateral oil supply port (63b) formed at a position closer to a base end
of the at least one gate (51) than a center, of the at least one gate (51), in a radial
direction of the gate rotor (50).
[0025] In the seventh aspect of the present disclosure, the lubricant in the oil supply
passage (5) is supplied to a portion of the side surface (51a, 51b) of the gate (51)
sliding on the screw rotor (40) closer to the base end than the center thereof in
the radial direction. The lubricant supplied to the portion of the side surface (51a,
51b) of the gate (51) closer to the base end is spread toward the distal end of the
gate (51) by the effect of the centrifugal force generated by the rotation of the
gate rotor (50).
[0026] An eighth aspect of the present disclosure is an embodiment of any one of the fourth
to seventh aspects. In the eighth aspect, the screw compressor (1) further comprises
a support member (55) supporting the gate rotor (50) from a rear side opposite to
the compression chamber (23), wherein an oil sump (62) to which the lubricant is supplied
is formed between the support member (55) and a coupling portion (52) of the gate
rotor (50) coupling base ends of the plurality of gates (51), and the oil supply passage
(5) extends in a radial direction of the gate rotor (50) of the at least one gate
(51), and has a base end connected to the oil sump (62).
[0027] In the eighth aspect of the present disclosure, the oil supply passage (5) extends
radially outward from the oil sump (62) closer to the base end than the gate (51).
In this configuration, the gate rotor (50) rotates to generate the centrifugal force,
which causes the lubricant to enter and flow radially outward through the oil supply
passage (5) extending from the oil sump (62) along the gate (51), and flow from the
lateral oil supply port (63b) to be supplied between the side surface (51a, 51b) of
the gate (51) and the screw rotor (40).
[0028] A ninth aspect of the present disclosure is an embodiment of any one of the first
to third aspects. In the ninth aspect, the oil supply passage (5) is formed in the
first rotor (40), and the oil supply port (4) is an in-groove oil supply port (66d)
opened at an inner surface (42) of the helical groove (41) serving as the sliding
surface (3) of the first rotor (40) sliding on the second rotor (50).
[0029] In the ninth aspect of the present disclosure, the oil supply passage (5) is formed
in the first rotor (40), and connected to the in-groove oil supply port (66d) opened
at the inner surface (42) of the helical groove (41) of the first rotor (40). In the
first rotor (40) configured in this manner, the lubricant in the oil supply passage
(5) flows from the in-groove oil supply port (66d) to the inner surface (42) of the
helical groove (41) which slides on the second rotor (50), thereby lubricating the
inner surface (42) of the helical groove, or sealing a gap, if any, between the inner
surface (42) and the second rotor (50) sliding on the inner surface (42). That is,
in the ninth aspect of the present disclosure, unlike the conventional configuration
in which the lubricant is injected from the oil supply port formed in the rotor casing
to be indirectly supplied to the inner surface (42) of the helical groove of the first
rotor (40), the lubricant is directly supplied to the inner surface (42) of the helical
groove serving as the sliding surface (3) from the in-groove oil supply port (66d)
opened at the inner surface (42) of the helical groove of the first rotor (40).
[0030] Further, in the ninth aspect of the present disclosure, unlike the conventional configuration
in which the lubricant is injected from the oil supply port formed in the rotor casing
that does not rotate, the oil supply port (4) is opened at the inner surface (42)
of the helical groove of the first rotor (40) that rotates, from which the lubricant
is allowed to flow to the inner surface (42). Therefore, the lubricant which has flowed
from the in-groove oil supply port (66d) is rapidly spread over the rotating first
rotor (40) by the effect of the centrifugal force, and thus, the lubricant is quickly
supplied to the sliding surfaces (3) other than the inner surface (42). Further, the
lubricant supplied to the inner surface (42) of the helical groove of the first rotor
(40) adheres to the second rotor (50) which meshes with and rotates with the first
rotor (40), and is rapidly spread over the second rotor (50) by the effect of the
centrifugal force. Thus, the lubricant is quickly supplied to the sliding surface
(3) of the second rotor (50).
[0031] A tenth aspect of the present disclosure is an embodiment of any one of the first
to third aspects. In the tenth aspect, the oil supply passage (5) is formed in the
first rotor (40), and the oil supply port (4) is an outer peripheral oil supply port
(66c) opened at an outer peripheral surface (43) of the first rotor (40) serving as
the sliding surface (3) of the first rotor (40) sliding on the rotor casing (30).
[0032] The outer peripheral surface (43) of the first rotor (40) provided with the helical
grooves (41) slides on the inner surface of the rotor casing (30) covering the outer
periphery of the first rotor (40). Thus, lubrication is required to keep the outer
peripheral surface (43) of the first rotor (40) and the inner surface of the rotor
casing (30) from seizing. On the other hand, when a gap is formed between the outer
peripheral surface of the first rotor (40) and the inner surface of the rotor casing
(30), the gap needs to be sealed so that the high pressure fluid does not leak to
the low pressure side.
[0033] In the tenth aspect of the present disclosure, the oil supply passage (5) is formed
in the first rotor (40), and connected to the outer peripheral oil supply port (66c)
opened at the outer peripheral surface (43) of the first rotor (40) that slides on
the rotor casing (30). In the first rotor (40) configured in this manner, the lubricant
in the oil supply passage (5) flows from the outer peripheral oil supply port (66c)
to the outer peripheral surface (43) of the first rotor (40) that slides on the inner
surface of the rotor casing (30), thereby lubricating the outer peripheral surface
(43), or sealing a gap, if any, between the outer peripheral surface (43) and the
inner surface of the rotor casing (30).
[0034] Further, in the tenth aspect of the present disclosure, unlike the conventional configuration
in which the lubricant is injected from the oil supply port formed in the rotor casing
that does not rotate, the oil supply port (4) is opened at the outer peripheral surface
(43) of the first rotor (40) that rotates, from which the lubricant is allowed to
flow to the outer peripheral surface (43). Therefore, the lubricant that has flowed
from the outer peripheral oil supply port (66c) is rapidly spread over the rotating
first rotor (40), and is quickly supplied to the sliding surfaces (3) other than the
outer peripheral surface (43) at which the outer peripheral oil supply port (66c)
is formed. Since the first rotor (40) and the second rotor (50) mesh with each other
to rotate together, the lubricant supplied to the first rotor (40) is rapidly spread
to the second rotor (50). Thus, the lubricant can be quickly supplied to the sliding
surface (3) of the second rotor (50).
[0035] An eleventh aspect of the present disclosure is an embodiment of the ninth or tenth
aspect. In the eleventh aspect, the first rotor (40) has an oil sump (44) to which
the lubricant is supplied, the oil sump (44) being formed at a position closer to
a rotation axis of the first rotor (40) than a bottom face (42c) of the helical groove
(41), and the oil supply passage (5) extends from the oil sump (44) toward an outer
periphery of the first rotor (40).
[0036] In the eleventh aspect of the present disclosure, the oil supply passage (5) extends
from the oil sump (44) closer to the rotation axis than the bottom face (42c) of the
helical groove (41) of the first rotor (40) toward the outer periphery of the first
rotor (40). In this configuration, the first rotor (40) rotates to generate the centrifugal
force, which causes the lubricant to enter the oil supply passage (5) from the oil
sump (44), flow toward the outer periphery of the first rotor (40), and flow from
the oil supply port (4) to be supplied to the sliding surface (3) of the first rotor
(40).
ADVANTAGES OF THE INVENTION
[0037] According to the first aspect of the present disclosure, the oil supply passage
(5) is formed in at least one of the rotors (40, 50), i.e., the first rotor (40) and
the second rotor (50) which mesh with each other and rotate together, and the oil
supply passage (5) is connected to the oil supply port (4) opened at the sliding surface
(3) of the rotor (40, 50) so that the lubricant is directly supplied from the oil
supply port (4) to the sliding surface (3). This makes it possible to reliably supply
the lubricant to the sliding surface (3) of the rotor (40, 50).
[0038] Further, according to the first aspect of the present disclosure, unlike the conventional
configuration in which the lubricant is injected from the oil supply port formed in
the rotor casing which does not rotate, the oil supply port (4) is opened at the sliding
surface (3) of the rotor (40, 50) that rotates, from which the lubricant is allowed
to flow to the sliding surface (3). Therefore, the lubricant that has flowed from
the oil supply port (4) is rapidly spread over the rotating rotor (40, 50), and can
be quickly supplied to the sliding surface (3) other than the sliding surface (3)
at which the oil supply port (4) is formed. Since the first rotor (40) and the second
rotor (50) mesh with each other and rotate together, the lubricant supplied to one
of the rotors (40, 50) in which the oil supply passage (5) is formed is rapidly spread
to the other rotor (50, 40). Thus, the lubricant can be quickly supplied to the sliding
surface (3) of the other rotor (50, 40).
[0039] As described above, according to the first aspect of the present disclosure, the
efficiency of the compressor is not lowered because it is unnecessary to increase
the power for the transport of the lubricant and the power for the rotation of the
first and second rotors (40, 50), unlike in the conventional configuration in which
a large amount of lubricant is supplied. Supplying the lubricant in a small amount
to at least one of the sliding surface (3) of the first rotor (40) or the sliding
surface (3) of the second rotor (50) makes it possible to lubricate the sliding surface
(3) of each of the first rotor (40) and the second rotor (50), or to seal the gap,
if any, between the sliding surface (3) and its counterpart sliding surface. That
is, according to the first aspect of the present disclosure, the sliding surfaces
(3) of the first rotor (40) and the second rotor (50) can be kept from seizing, and
the high pressure fluid can be blocked from leaking from the compression chamber,
even if the supply amount of the lubricant is reduced. Therefore, according to the
first aspect of the present disclosure, the supply amount of the lubricant can be
reduced without lowering the reliability of the screw compressor (1), which can improve
the compressor efficiency.
[0040] According to the second aspect of the present disclosure, the oil supply passage
(5) can be switched between the supply state in which the lubricant is supplied from
the oil supply passage (5) to the sliding surface (3), and the non-supply state in
which no lubricant is supplied from the oil supply passage (5) to the sliding surface
(3). Thus, in a situation where the sliding surface (3) of the rotor (40, 50) provided
with the oil supply port (4) is not configured to slide constantly, the oil supply
passage can be switched to the non-supply state to stop the supply of the lubricant
to the sliding surface (3) when the sliding surface (3) does not slide and requires
no lubrication. Therefore, according to the second aspect of the present disclosure,
the lubricant can be reliably supplied to the sliding surface (3) of the rotor (40,
50), while reducing the amount of the lubricant supplied.
[0041] In the third aspect of the present disclosure, when the rotational angle position
of the rotor (40, 50) provided with the oil supply passage (5) is in the predetermined
angle range, the oil supply source (94c, 95c) communicates with the oil supply passage
(5), and the oil supply passage (5) is switched to the supply state. When the rotational
angle position of the rotor (40, 50) is out of the predetermined angle range, the
oil supply source (94c, 95c) and the oil supply passage (5) are blocked from each
other, and the oil supply passage (5) is switched to the non-supply state. Such a
simple configuration of the third aspect of the present disclosure makes it possible
to automatically switch the oil supply passage (5) between the supply state and the
non-supply state while the rotor (40, 50) provided with the oil supply passage (5)
makes a single rotation.
[0042] According to the fourth aspect of the present disclosure, each of the gates (51)
of the gate rotor (50) is provided with the oil supply passage (5) which directly
supplies the lubricant to the side surface (51a, 51b) which slide on the screw rotor
(51) and need to be lubricated and sealed by the lubricant. Thus, as compared to the
conventional configuration in which the lubricant is injected into the helical groove
(41) to be indirectly supplied to the sliding surfaces (3) of the gate rotor (50)
and the screw rotor (40), the lubricant can be reliably supplied to the sliding surfaces
(3) of the gate (51) and the screw rotor (40) in a smaller amount, thereby lubricating
the sliding surfaces (3), or sealing a gap, if any, between the sliding surfaces (3).
Moreover, the lubricant supplied in this manner to the sliding surfaces (3) of the
screw rotor (40) and the gate (51) also adheres to the screw rotor (40), and is spread
toward the outer periphery of the screw rotor (40) by the effect of the centrifugal
force generated by the rotation of the screw rotor (40). Thus, the lubricant can also
be supplied to a gap between the screw rotor (40) and the cylindrical wall (30) to
seal the gap.
[0043] As described above, according to the fourth aspect of the present disclosure, the
efficiency of the compressor is not lowered because it is unnecessary to increase
the power for the transport of the lubricant and the power for the rotation of the
screw rotor (40), unlike in the conventional configuration in which a large amount
of lubricant is supplied. Directly supplying the lubricant in a small amount to the
sliding surfaces (3) of the gate (51) and the screw rotor (40) makes it possible to
lubricate the gate (51) and the screw rotor (40), and the screw rotor (40) and the
cylindrical wall (30), and to seal the gap between the gate (51) and the screw rotor
(40), and the gap between screw rotor (40) and the cylindrical wall (30), if any.
That is, according to the fourth aspect of the present disclosure, the gate rotor
(50) and the screw rotor (40) can be kept from seizing, and the high pressure fluid
can be blocked from leaking from the compression chamber, even if the supply amount
of the lubricant is reduced. Therefore, according to the fourth aspect of the present
disclosure, the supply amount of the lubricant can be reduced without lowering the
reliability of the single-screw compressor (1), which can improve the compressor efficiency.
[0044] According to the fifth aspect of the present disclosure, the lateral oil supply port
(63b) of the oil supply passage (5) is opened at least at the side surface (51b) of
the gate (51) on the rear side in the direction of rotation of the gate (51). The
rear side surface (51b) in the rotation direction of the gate (51) is the sliding
surface (3) which reliably slides on the screw rotor (40) and is pressed by the screw
rotor (40), and therefore, is probably worn through the sliding movement. However,
the lateral oil supply port (63b) opened at the rear side surface (51b) causes the
lubricant to be reliably supplied between the rear side surface (51b) and the lateral
face of the helical groove (41). This can protect the gate (51) and the screw rotor
(40) from the sliding wear.
[0045] According to the sixth aspect of the present disclosure, the oil supply passage (5)
of the gate (51) is connected to not only the lateral oil supply port (63b) which
is opened at the side surface (51a, 51b) that slide on the screw rotor (40) of the
gate (51), but also the front oil supply port (63c) which is opened at the front surface
(51c) of the gate (51). Thus, in the gate (51) of the gate rotor (50), the lubricant
in the oil supply passage (5) can be supplied not only to the side surface (51a, 51b)
that slide on the screw rotor (40), but also to the front surface (51c) that faces
the compression chamber (23). As a result, the lubricant is supplied between the front
surface (51c) of the gate (51) and the cylindrical wall (30) to lubricate the front
surface (51c) and the cylindrical wall (30), or seal a gap, if any, between the front
surface (51c) and the cylindrical wall (30). This can keep the seizing caused by the
sliding movement of the gate (51), and can block the fluid from leaking from the high
pressure compression chamber (23) through the gap between the front surface (51c)
of the gate (51) and the cylindrical wall (30) to the low-pressure space outside the
cylindrical wall (30) where the gate rotor (50) is disposed.
[0046] According to the seventh aspect of the present disclosure, the lateral oil supply
port (63b) opened at the side surface (51a, 51b) of the gate (51) which slides on
the screw rotor (40) includes at least one lateral oil supply port (63b) formed at
a position closer to the base end of the gate (51) than the center thereof in the
radial direction of the gate (51). The at least one lateral oil supply port (63b)
formed at the position closer to the base end of the gate (51) than the center thereof
in the radial direction makes it possible to supply the lubricant to the base end
of the side surface (51a, 51b) of the gate (51), and to easily spread the lubricant
toward the distal end of the side surface (51a, 51b) of the gate (51) by utilizing
the centrifugal force. This configuration can minimize the number of the lateral oil
supply ports (63b), and can further reduce the supply amount of the lubricant.
[0047] According to the eighth aspect of the present disclosure, the oil sump (62) is formed
between the support member (55) supporting the gate rotor (50) and the coupling portion
(52) of the gate rotor (50) coupling the base ends of the gates (51), and an end of
the oil supply passage (5) toward the base ends of the gates (51) is connected to
the oil sump (62). That is, the oil supply passage (5) extends radially outward from
the oil sump (62) along the corresponding gate (51). In this configuration, the gate
rotor (50) rotates to generate the centrifugal force, which causes the lubricant in
the oil sump (62) to enter and flow radially outward through the oil supply passage
(5) in the gate (51), and flows from the lateral oil supply port (63b) to be supplied
between the side surface (51a, 51b) of the gate (51) and the screw rotor (40). That
is, this simple configuration can supply the lubricant between the side surface (51a,
51b) of the gate (51) and the screw rotor (40) by utilizing the centrifugal force
generated by the rotation of the gate rotor (50).
[0048] According to the ninth aspect of the present disclosure, the oil supply passage (5)
is formed in the first rotor (40), and connected to the in-groove oil supply port
(66d) opened at the inner surface (42) of the helical groove (41) of the first rotor
(40), so that the lubricant is directly supplied from the in-groove oil supply port
(66d) to the inner surface (42) of the helical groove, which is the sliding surface
(3) which slides on the second rotor (50). Thus, as compared to the conventional configuration
in which the lubricant is injected from the oil supply port formed in the rotor casing
to be indirectly supplied to the inner surface (42) of the helical groove of the first
rotor (40), the lubricant can be reliably supplied in a smaller amount to the inner
surface (42) of the helical groove of the first rotor (40). Further, the in-groove
oil supply port (66d) is opened at the inner surface (42) of the helical groove of
the first rotor (40) that rotates, from which the lubricant is allowed to flow to
the inner surface (42). Thus, the lubricant that has flowed from the in-groove oil
supply port (66d) is rapidly spread over the rotating first rotor (40), and the lubricant
can also be quickly supplied to the sliding surface (3) other than the inner surface
(42). The lubricant supplied to the inner surface (42) of the helical groove of the
first rotor (40) also adheres to the second rotor (50) which meshes with and rotates
with the first rotor (40), and is rapidly spread over the second rotor (50) by the
effect of the centrifugal force. Thus, the lubricant can be quickly supplied to the
sliding surface (3) of the second rotor (50).
[0049] According to the tenth aspect of the present disclosure, the oil supply passage (5)
is formed in the first rotor (40), and connected to the outer peripheral oil supply
port (66c) formed at the outer peripheral surface (43) which slides on the rotor casing
(30) of the first rotor (40), so that the lubricant is directly supplied from the
outer peripheral oil supply port (66c) to the outer peripheral surface (43) which
is the sliding surface (3). This makes it possible to reliably supply the lubricant
to the outer peripheral surface (43) of the first rotor (40) which slides on the inner
surface of the rotor casing (30).
[0050] Further, according to the tenth aspect of the present disclosure, unlike the conventional
configuration in which the lubricant is injected from the oil supply port formed in
the rotor casing that does not rotate, the oil supply port (4) is opened at the outer
peripheral surface (43) of the first rotor (40) that rotates, from which the lubricant
is allowed to flow to the outer peripheral surface (43). Therefore, the lubricant
that has flowed from the outer peripheral oil supply port (66c) is rapidly spread
over the rotating first rotor (40), and is quickly supplied to the sliding surface
(3) other than the outer peripheral surface (43) of the first rotor (40) at which
the outer peripheral oil supply port (66c) is formed. Since the first rotor (40) and
the second rotor (50) mesh with each other and rotate together, the lubricant supplied
to the first rotor (40) is rapidly spread to the second rotor (50). Thus, the lubricant
can be quickly supplied to the sliding surface (3) of the second rotor (50).
[0051] According to the eleventh aspect of the present disclosure, the oil sump (44) is
formed at a position closer to the rotation axis of the first rotor (40) than the
bottom face (42c) of the helical groove (41), and a base end of the oil supply passage
(5) is connected to the oil sump (44). That is, the oil supply passage (5) extends
from the oil sump (44) in the first rotor (40) toward the outer periphery. In this
configuration, the first rotor (40) rotates to generate the centrifugal force, which
causes the lubricant to enter the oil supply passage (5) from the oil sump (44), flow
toward the outer periphery of the first rotor (40), and flow from the oil supply port
(4) to be supplied to the sliding surface (3) of the first rotor (40). That is, this
simple configuration can supply the lubricant to the sliding surface (3) of the first
rotor (40) by utilizing the centrifugal force generated by the rotation of the first
rotor (40).
BRIEF DESCRIPTION OF THE DRAWINGS
[0052]
FIG. 1 is a diagram schematically showing a general configuration of a screw compressor
according to a first embodiment.
FIG. 2 is a vertical sectional view illustrating the vicinity of a compression mechanism
of the screw compressor.
FIG. 3 is a cross-sectional view illustrating the vicinity of the compression mechanism
of the screw compressor.
FIG. 4 is a perspective view illustrating a screw rotor and gate rotors taken out
of the screw compressor.
FIG. 5 is an enlarged view illustrating a right side portion of FIG. 3.
FIG. 6 is a perspective view illustrating a support member shown in FIG. 5.
FIG. 7 is a vertical sectional view schematically illustrating the gate rotor and
the screw rotor meshing with each other in an enlarged scale.
FIG. 8 is a sectional view illustrating a gate of the gate rotor and an arm of the
support member in a helical groove of the screw rotor.
FIG. 9 is an enlarged view of a left side portion of FIG. 3.
FIGS. 10A to 10C are plan views respectively illustrating how a compression mechanism
of a single-screw compressor is operated in a suction phase, a compression phase,
and a discharge phase.
FIG. 11 is a cross-sectional view corresponding to FIG. 5, illustrating a screw compressor
according to a second embodiment.
FIG. 12 is a cross-sectional view corresponding to FIG. 9, illustrating the screw
compressor of the second embodiment.
FIG. 13 is a vertical sectional view corresponding to FIG. 7, illustrating the screw
compressor of the second embodiment.
FIG. 14 is a sectional view taken along line XIV-XIV in FIGS. 11 and 12.
FIG. 15 is a cross-sectional view illustrating the vicinity of a compression mechanism
of a screw compressor of a third embodiment.
DESCRIPTION OF EMBODIMENTS
[0053] Embodiments of the present disclosure will be described in detail with reference
to the drawings.
<<First Embodiment>>
[0054] A screw compressor according to a first embodiment is a single-screw compressor (1)
provided in a refrigerant circuit for performing a refrigeration cycle, and compresses
a refrigerant (fluid).
[0055] As shown in FIG. 1, in the single-screw compressor (1), a compression mechanism (20)
and an electric motor (15) driving the compression mechanism are housed in a single
casing (10). The single-screw compressor (1) is configured as a semi-hermetic compressor.
[0056] The casing (10) has an outer wall (17) in the shape of a laterally oriented cylinder.
Space inside the casing (10) is divided into a low-pressure space (S1) located at
one of longitudinal ends of the outer wall (17), and a high-pressure space (S2) located
at the other longitudinal end. The casing (10) is provided with a suction pipe connector
(11) communicating with the low-pressure space (S1), and a discharge pipe connector
(12) communicating with the high-pressure space (S2). Although not shown, a low pressure
gas refrigerant flowing from an evaporator of a refrigerant circuit in a refrigeration
apparatus, such as a chiller system, flows into the low-pressure space (S1) through
the suction pipe connector (11). A compressed, high pressure gas refrigerant discharged
from the compression mechanism (20) into the high-pressure space (S2) passes through
the discharge pipe connector (12), and is supplied to a condenser of the refrigerant
circuit.
[0057] Inside the outer wall (17) of the casing (10), the electric motor (15) is arranged
in the low-pressure space (S1), and the compression mechanism (20) is arranged between
the low-pressure space (S1) and the high-pressure space (S2). The compression mechanism
(20) has a drive shaft (21) coupled to the electric motor (15). The electric motor
(15) of the single-screw compressor (1) is connected to a commercial power supply
(not shown). The electric motor (15) is supplied with an alternating current from
the commercial power supply, and rotates at a predetermined rotational speed.
[0058] Inside the outer wall (17) of the casing (10), an oil separator (16a) is disposed
in the high-pressure space (S2). The oil separator (16a) separates a lubricant from
the refrigerant discharged from the compression mechanism (20). An oil reservoir chamber
(16b) for storing the lubricant (lubricating oil) is formed in the high-pressure space
(S2) below the oil separator (16a). The lubricant separated from the refrigerant in
the oil separator (16a) flows downward and accumulates in the oil reservoir chamber
(16b). The lubricant accumulated in the oil reservoir chamber (16b) has high pressure
which is substantially equal to the discharge pressure of the refrigerant.
[0059] As shown in FIGS. 2 and 3, the compression mechanism (20) includes a cylindrical
wall (rotor casing) (30), a single screw rotor (a first rotor) (40), and two gate
rotors (second rotors) (50) which mesh with the screw rotor (40).
[0060] The cylindrical wall (30) is a cylinder-shaped thick wall, and is integrated with
the outer wall (17) to be part of the casing (10). The screw rotor (40) is rotatably
housed in the cylindrical wall (30). A bearing holder (35) is fitted in a portion
of the cylindrical wall (30) closer to the high-pressure space (S2) of the screw rotor
(40).
[0061] A drive shaft (21) arranged coaxially with the screw rotor (40) is inserted through
the screw rotor (40). The screw rotor (40) and the drive shaft (21) are connected
to each other by a key (22). The screw rotor (40) is driven to rotate in the casing
(10) by the electric motor (15) disposed on the suction side of the screw rotor (40).
One end of the drive shaft (21) is supported by the bearing holder (35) held by the
cylindrical wall (30), via a bearing (36), and the other end is connected to the electric
motor (15).
[0062] As shown in FIG. 4, the screw rotor (40) is a metal member which is substantially
in the shape of a cylindrical column. The screw rotor (40) is rotatably fitted in
the cylindrical wall (30). The screw rotor (40) has an outer diameter slightly smaller
than an inner diameter of the cylindrical wall (30), and has an outer peripheral surface
(43) which slides on an inner peripheral surface (30a) of the cylindrical wall (30)
with a film of the lubricant present therebetween. That is, the outer peripheral surface
(43) of the screw rotor (40) is configured as a sliding surface (3) which slides on
the inner peripheral surface (30a) of the cylindrical wall (30). The screw rotor (40)
has, on its outer periphery, a plurality of helical grooves (41) (six grooves in this
embodiment) helically extending from one axial end of the screw rotor (40) to the
other.
[0063] Each of the helical grooves (41) of the screw rotor (40) has a left end in FIG. 4
serving as a starting end, and a right end in FIG. 4 serving as a terminal end. A
left end (an end on the suction side) of the screw rotor (40) in FIG. 4 is tapered.
In the screw rotor (40) shown in FIG. 4, the starting end of the helical groove (41)
is opened at the tapered left end face of the screw rotor (40), while the terminal
end of the helical groove (41) is not opened at a right end face of the screw rotor
(40). An inner surface (42) of the helical groove (41) includes a lateral face (42a)
on the front side in a direction of rotation of the screw rotor (40), a lateral face
(42b) on the rear side in the direction of rotation, and a bottom face (42c) connecting
the bottom ends of the lateral faces (42a, 42b).
[0064] As shown in FIGS. 3 to 5 and FIGS. 7 to 9, each of the gate rotors (50) is a flat
member made of a resin. Each gate rotor (50) has a plurality of (eleven in this embodiment)
gates (51), each of which is formed in a rectangular plate shape, and a planar coupling
portion (52) coupling base ends of the plurality of gates (51). The gate rotor (50)
is in the shape of a gear. The two gate rotors (50) are arranged outside the cylindrical
wall (30) to be axially symmetric with respect to the rotation axis of the screw rotor
(40). The rotation axis of each gate rotor (50) is in a plane orthogonal to the center
axis of the screw rotor (40).
[0065] Each of the gate rotors (50) is attached to a support member (55) made of metal.
As shown in FIG. 6, the support member (55) includes a base (56), arms (57), and a
shaft (58). The base (56) is in the shape of a relatively thick disk. The arms (57)
are provided in the same number (eleven in this embodiment) as the gates (51) of the
gate rotor (50), and extend radially outward from an outer peripheral surface of the
base (56). Each of the arms (57) abuts on a rear surface of an associated one of the
gates (51), thereby supporting the gate (51) from the rear side. The shaft (58) is
in a rod shape and coupled to a center portion of the base (56). The shaft (58) has
a center axis which coincides with the center axis of the base (56). The shaft (58)
penetrates through the center portion of the gate rotor (50), and is formed to extend
forward and rearward of the gate rotor (50). In this embodiment, the shaft (58) has
a front shaft portion (58a) which extends forward of the base (56) and is longer than
a rear shaft portion (58b) which extends rearward of the base (56).
[0066] The support members (55) to each of which the gate rotor (50) is attached are respectively
housed in gate rotor chambers (90) defined inside the casing (10) to be adjacent to
the cylindrical wall (30) (see FIG. 3). Each of the gate rotor chambers (90) communicates
with the low-pressure space (S1).
[0067] As shown in an enlarged scale in FIGS. 5 and 9, first and second bearing holders
(94, 95) formed as an integral part of the casing (10) are provided in each of the
gate rotor chambers (90). Each of the first and second bearing holders (94, 95) has
a tubular portion (94a, 95a) having a cylindrical shape and a closed bottom, and a
flange (94b, 95b) formed around a base end of the tubular portion (94a, 95a). The
tubular portion (94a, 95a) of each of the first and second bearing holders (94, 95)
is inserted into the gate rotor chamber (90) through an opening formed in the casing
(10), and the flange (94b, 95b) is fixed to a portion around the opening of the casing
(10). A bearing (92) is held at a distal end of the tubular portion (94a) of the first
bearing holder (94), and a bearing (93) is held at a distal end of the tubular portion
(95a) of the second bearing holder (95).
[0068] The inside of the tubular portion (94a) of the first bearing holder (94) serves as
an oil sump (94c) which stores the lubricant to be supplied to the bearing (92) at
the distal end thereof. The inside of the second bearing holder (95) serves as an
oil sump (95c) which stores the lubricant to be supplied to the bearing (93) at the
distal end thereof. The oil sumps (94c, 95c) communicate with the oil reservoir chamber
(16b) formed in the high-pressure space (S2) through a passage (not shown). Each of
the oil sumps (94c, 95c) stores the high pressure lubricant supplied from the oil
reservoir chamber (16b) through the passage (not shown), and the lubricant reaches
a sliding portion of the bearing (93, 94) to lubricate the sliding portion.
[0069] The support member (55) on the right of the screw rotor (40) and the support member
(55) on the left of the screw rotor (3) in FIG. 3 are inverted from each other in
the vertical direction. Specifically, the support member (55) on the right in FIG.
3 has the front shaft portion (58a) located above the rear shaft portion (58b) (see
FIG. 5). The support member (55) on the left in FIG. 3 has the front shaft portion
(58a) located below the rear shaft portion (58b) (see FIG. 9). The front shaft portion
(58a) of each support member (55) is rotatably supported by the second bearing holder
(95) in each gate rotor chamber (90) via the bearing (93), and the rear shaft portion
(58b) of each support member (55) is rotatably supported by the first bearing holder
(94) in each gate rotor chamber (90) via the bearing (92).
[0070] The casing (10) is provided with an opening (13) through which an assembly of the
gate rotor (50) and the support member (55) can be inserted into the inside of the
gate rotor chamber (90) from the outside of the casing (10), and a cover member (14)
for covering the opening (13).
[0071] The cylindrical wall (30) has an opening (39) which allows each of the gate rotor
chambers (90) to communicate with a screw rotor chamber formed inside the cylindrical
wall (30). In each of the gate rotor chambers (90), the assembly of the gate rotor
(50) and the support member (55) is disposed at a position where the gate (51) enters
the inside of the cylindrical wall (30) through the opening (39) and meshes with the
screw rotor (40) (enters the helical groove (41)). An end face of the cylindrical
wall (30) forming the opening (39) and facing a front surface (51c) of the gate (51)
toward the compression chamber (23) serves as a sealing surface (39a). The sealing
surface (39a) is a flat surface extending in the axial direction of the screw rotor
(40) along the outer periphery of the screw rotor (40). A distance between each gate
rotor (50) and the sealing surface (39a) is set to be very small (e.g., 40 µm or less)
so that the leakage of the fluid compressed in the compression chamber (23) to the
gate rotor chamber (90) is reduced as much as possible.
[0072] In the compression mechanism (20), a space surrounded by the inner peripheral surface
(30a) of the cylindrical wall (30), the inner surface (42) forming the helical groove
(41) of the screw rotor (40), and the front surface (51c) of the gate (51) of the
gate rotor (50) functions as the compression chamber (23) for compressing the fluid.
An end of the helical groove (41) of the screw rotor (40) on the suction side is opened
toward the low-pressure space (S1), and this open end serves as a suction port (24)
of the compression mechanism (20).
[Unloading Mechanism]
[0073] The single-screw compressor (1) is provided with an unloading mechanism (70, 80)
which controls an operating capacity by performing an unloading operation of returning
a portion of the gas in the course of the compression to a low pressure side. The
unloading mechanism (70, 80) is composed of slide valves (70) and a slide valve driving
mechanism (80).
[0074] The slide valves (70) are respectively arranged in slide valve housings (31). As
shown in FIG. 2, the slide valve housings (31) are formed at two positions in the
circumferential direction of the cylindrical wall (30). Each of the slide valves (70)
is configured to be slidable in the axial direction of the cylindrical wall (30),
and faces the outer peripheral surface (43) of the screw rotor (40) when the slide
valve (70) is inserted into an associated one of the slide valve housings (31). The
slide valve (70) is fully opened when it moves to an end toward the discharge side
(the right side) in FIG. 2, or fully closed when it moves to an end toward the suction
side.
[0075] In the casing (10), communication passages (32) are formed outside the cylindrical
wall (30). The communication passages (32) are formed in one-to-one correspondence
with the slide valve housings (31). Each of the communication passages (32) has one
end opened in the low-pressure space (S1), and the other end opened at an end on the
suction side of the corresponding slide valve housing (31).
[0076] When the slide valves (70) slide toward the high-pressure space (S2) (i.e., to the
right when the axial direction of the drive shaft (21) in FIG. 2 is regarded as the
lateral direction), axial gaps (G) are formed between end faces of the slide valve
housings (31) and end faces of bypass opening degree regulating portions (71) of the
slide valves (70). Each axial gap (G) forms, together with an associated one of the
communication passages (32), a bypass passage (33) through which the refrigerant in
the course of compression in the compression chamber (23) is returned to the low-pressure
space (S1). That is to say, the bypass passage (33) has one end communicating with
the low-pressure space (S1) corresponding to the suction side of the compression chamber
(23), and the other end openable at the inner peripheral surface (30a) of the cylindrical
wall (30) where the compression in the compression chamber (23) is in progress. When
the slide valves (70) are moved to change the opening degree of the bypass passages
(33), a flow rate of the refrigerant returning from the position where the compression
is in progress to the low-pressure space varies. As a result, the capacity of the
compression mechanism (20) varies.
[0077] Each slide valve (70) includes the bypass opening degree regulating portion (71)
for regulating the opening degree of the bypass passage (33), and a discharge opening
regulating portion (72) for regulating an opening area of the discharge port (25)
which is formed in the cylindrical wall (30) to allow the compression chamber (23)
to communicate with the high-pressure space (S2). The slide valves (70) are slidable
in the axial direction of the screw rotor (40). The discharge opening regulating portion
(72) of the slide valve (70) is configured to vary the opening area of the discharge
port (25) in accordance with the change in the position of the slide valve (70).
[0078] The slide valve driving mechanism (80) includes a cylinder tube (81), a piston (82)
inserted in the cylinder tube (81), an arm (84) connected to a piston rod (83) of
the piston (82), a connecting rod (85) connecting the arm (84) and the slide valve
(70), and a spring (86) for biasing the arm (84) to the right in FIG. 2 (in a direction
in which the arm (84) is separated from the casing (10)). The cylinder tube (81) and
the piston (82) are components forming a hydraulic cylinder (hydropneumatic cylinder)
(87). In this embodiment, one of axial end portions of the bearing holder (35) opposite
to the screw rotor (40) is configured as the cylinder tube (81). The hydraulic cylinder
(87) is disposed across the bearing (36) from the screw rotor (40), and is integrated
with the bearing holder (35) holding the bearing (36).
[0079] Inside the bearing holder (35), a partition plate (38) is provided to define a bearing
chamber (C1) where the bearing (36) is held and a cylinder chamber (C2) where the
piston (82) of the hydraulic cylinder (87) is housed.
[0080] When the slide valve driving mechanism (80) is in the state shown in FIG. 2, the
internal pressure of a space in the cylinder chamber (C2) on the left of the piston
(82) (space on the side of the piston (82) toward the screw rotor (40)) is higher
than the internal pressure of a space on the right of the piston (82) (space on the
side of the piston (82) toward the arm (84)). The slide valve driving mechanism (80)
is configured to adjust the position of the slide valves (70) by regulating the internal
pressure of the space on the right of the piston (82) (i.e., the gas pressure in the
right space). Thus, although not shown, a passage for regulating the pressure in the
right space of the piston (82) is formed in the bearing holder (35).
[0081] While the single-screw compressor (1) is in operation, a suction pressure of the
compression mechanism (20) acts on one of the axial end faces of each slide valve
(70) (i.e., the end face of the bypass opening degree regulating portion (71)), and
a discharge pressure of the compression mechanism (20) acts on the other of the axial
end faces of each slide valve (70). Consequently, during the operation of the single-screw
compressor (1), a force pushing the slide valves (70) toward the low-pressure space
(S1) constantly acts on the slide valves (70). Therefore, if the internal pressures
of the left and right spaces of the piston (82) of the slide valve driving mechanism
(80) vary, the magnitude of a force pulling the slide valves (70) back toward the
high-pressure space (S2) varies, which changes the positions of the slide valves (70).
[Oil Supply Mechanism]
[0082] As shown in FIG. 3 and FIGS. 5 to 9, the single-screw compressor (1) is provided
with an oil supply mechanism (60) for supplying the lubricant to the side surfaces
(51a, 51b) and front surface (51c) of the gate (51) constituting the sliding surface
(3) of the gate rotor (50). In this embodiment, the oil supply mechanism (60) is provided
for each of the two gate rotors (50). In the following description, the oil supply
mechanism (60) which supplies the lubricant to the sliding surface (3) of the gate
rotor (50) on the right in FIG. 3, which is enlarged in FIG. 5, will be referred to
as a "right oil supply mechanism (60)," and the oil supply mechanism (60) which supplies
the lubricant to the sliding surface (3) of the gate rotor (50) on the left in FIG.
3, which is enlarged in FIG. 9, will be referred to as a "left oil supply mechanism
(60)." Each of the two oil supply mechanisms (60) has an in-shaft communication passage
(61), an oil sump (62), and a plurality of gate-side oil supply passages (63) (oil
supply passages (5)).
(Right Oil Supply Mechanism)
[0083] In the right oil supply mechanism (60) shown in FIGS. 5 and 6, the in-shaft communication
passage (61) is formed inside the front shaft portion (58a). The in-shaft communication
passage (61) includes a longitudinal communication passage (61a) and two lateral communication
passages (61b). The longitudinal communication passage (61a) extends straight in the
axial direction to pass through the center of the front shaft portion (58a) from one
end to the other end thereof. Each of the two lateral communication passages (61b)
extends from the other end (an end toward the base (56)) of the longitudinal communication
passage (61a) to the outside in a radial direction of the front shaft portion (58a),
and is opened at the outer peripheral surface of the front shaft portion (58a).
[0084] The oil sump (62) is formed between the coupling portion (52) coupling base ends
of the gates (51) and the base (56), of the support member (55), corresponding to
the coupling portion (52). Specifically, a space defined by a groove (62a) formed
in the coupling portion (52) of the gate rotor (50) and a groove (62b) formed in the
base (56) of the support member (55) is configured as the oil sump (62). The groove
(62a) in the gate rotor (50) and the groove (62b) in the support member (55) are formed
in an annular shape. As shown in FIG. 6, the groove (62b) formed in the base (56)
of the support member (55) is formed in an annular shape to surround the outer periphery
of the front shaft portion (58a), and is opened at the front surface of the base (56)
facing the gate rotor (50). The two lateral communication passages (61b) of the in-shaft
communication passage (61) are opened in the groove (62b). This configuration allows
the oil sump (62) to communicate with the oil sump (95c) of the second bearing holder
(95) above the front shaft portion (58a) via the in-shaft communication passage (61).
[0085] The gate-side oil supply passages (63) are respectively formed in the gates (51)
of the gate rotor (50). In this embodiment, the gate-side oil supply passages (63)
are formed in all of the eleven gates (51). Each of the gate-side oil supply passages
(63) includes a body (53), a plurality of lateral branches (54), and a front branch
(59).
[0086] Specifically, as shown in FIG. 5, grooves (63a) extending in the radial direction
of the gate rotor (50) are respectively formed in the rear surfaces of the gates (51).
The grooves (63a) are closed by front surfaces of the arms (57) respectively supporting
the gates (51) from the rear side. Space in each of the grooves (63a) closed by the
front surfaces of the arms (63) constitutes the body (53) of each of the gate-side
oil supply passages (63). As shown in FIG. 7, the body (53) of each gate-side oil
supply passage (63) extends radially from the base end to distal end of the gate (51).
A base end of the body (53) is connected to the oil sump (62) formed between the coupling
portion (52) coupling the base ends of the gates of the gate rotor (50) and the base
(56) of the support member (55).
[0087] As shown in FIGS. 7 and 8, the lateral branches (54) are formed by holes extending
from the body (53) in the circumferential direction of the gate rotor (50), and are
connected to lateral oil supply ports (63b) which are opened at side surfaces (51a,
51b) of the gate (51). The lateral oil supply ports (63b) constitute oil supply ports
(4) for supplying the lubricant to the side surfaces (51a, 51b), which are the sliding
surfaces (3), of each gate (51). In this embodiment, each of the gates (51) is provided
with four lateral branches (54) on the front side, and four lateral branches (54)
on the rear side, in the rotation direction thereof. Thus, in this embodiment, four
lateral oil supply ports (63b) are opened at the front side surface (51a) in the rotation
direction of the gate (51), and four lateral oil supply ports (63b) are opened at
the rear side surface (51b). The four lateral oil supply ports (63b) at the front
side surface (51a) and the four oil supply ports (63b) at the rear side surface (51b)
are provided at positions corresponding to each other. The four lateral oil supply
ports (63b) at each side surface (51a, 51b) are arranged at substantially equal intervals
from the base end to distal end of the gate (51). The diameter of each of the lateral
oil supply ports (63b) and lateral branches (54) is determined so that the lubricant
flows in such an amount that allows an oil film to be formed on the side surfaces
(51a, 51b) of the gates (51), and that the lubricant is kept from scattering in the
shape of droplets.
[0088] The number of lateral oil supply ports (63b) and lateral branches (54) is not limited
to four, but may be less than four, or more than four. In a preferred embodiment,
the diameter is changed in accordance with the number so that the lubricant flows
in such an amount that allows an oil film to be formed on the side surfaces (51a,
51b) of the gates (51), and that the lubricant is kept from scattering in the shape
of droplets.
[0089] As shown in FIG. 8, each of the side surfaces (51a, 51b) of the gate (51) which slides
on the screw rotor (40) protrudes at a center portion in the thickness direction of
the gate. Each of the protruding center portion forms a seal line (L1, L2) which abuts
on the corresponding lateral face (42a, 42b) of the helical groove (41) of the screw
rotor (40). The lateral oil supply ports (63b) are opened at the side surfaces (51a,
51b) of each gate (51) at a position forward of the seal line (L1, L2), that is, toward
the compression chamber (23).
[0090] In this configuration, each of the gate-side oil supply passages (63) is connected
to the lateral oil supply ports (63b) opened at the side surfaces (51a, 51b) of the
gate (51) which slide on the screw rotor (40).
[0091] As shown in FIGS. 5, 7, and 8, the front branch (59) is a hole which extends in a
thickness direction of the gate (51) (a direction parallel to the axial direction
of the gate rotor (50)) from the groove (63a) (body (53)) extending in the radial
direction of the gate rotor (50) of the gate (51), and is opened at the front surface
(51c). The front branch (59) is connected to a front oil supply port (63c) opened
at the front surface (51c) of the gate (51). The front oil supply port (63c) constitutes
an oil supply port (4) for supplying the lubricant to the front surface (51c), which
is the sliding surface (3), of the gate (51). In this embodiment, the front branch
(59) is provided for each of the plurality of gates (51). Thus, in this embodiment,
a single front oil supply port (63c) is opened at each of the front surfaces (51c)
of the gates (51). In this embodiment, each of the front oil supply ports (63c) is
opened at a position further inward than the center of the front surface (51c) of
the gate (51) in the radial direction. The diameter of each of the front oil supply
ports (63c) and front branches (59) is determined so that the lubricant flows in such
an amount that allows an oil film to be formed on the front surfaces (51c) of the
gates (51), and that the lubricant is kept from scattering in the shape of droplets.
The number of front oil supply ports (63c) and front branches (59) is not limited
to one, but may be two or more. In a preferred embodiment, the diameter is changed
in accordance with the number so that the oil film is formed on the front surfaces
(51c) of the gates (51).
[0092] In this configuration, each of the gate-side oil supply passages (63) is connected
to the front oil supply port (63c) opened at the front surface (51c) of the gate (51)
facing the compression chamber (23).
[0093] As described above, in the right oil supply mechanism (60), the in-shaft communication
passage (61), the oil sump (62), and the plurality of gate-side oil supply passages
(63), which are formed in the gate rotor (50) and the support member (55), form a
lubricant passage which is branched to have two or more outlets. The lubricant passage
has an inlet which is opened in the oil sump (95c) of the second bearing holder (95)
in which the high pressure lubricant flowing from the oil reservoir chamber (16b)
is accumulated. Although some of the plurality of lateral oil supply ports (63b) and
the front oil supply port (63c), which are the outlets of the lubricant passage, are
opened in the compression chamber (23), most of them are opened in the gate rotor
chamber (90) communicating with the low-pressure space (S1). Therefore, due to the
pressure difference between the inlet and outlets of the lubricant passage, the high
pressure lubricant in the oil sump (95c) enters the lubricant passage, flows toward
the outlets, and then flows to the side surfaces (51a, 51b) and front surface (51c)
of each gate (51).
(Left Oil Supply Mechanism)
[0094] In the left oil supply mechanism (60) shown in FIG. 9, the in-shaft communication
passage (61) is formed inside the rear shaft portion (58b). The in-shaft communication
passage (61) includes a longitudinal communication passage (61a) and two lateral communication
passages (61b). The longitudinal communication passage (61a) extends straight in the
axial direction to pass through the center of the rear shaft portion (58b) from one
end to the other end thereof. Each of the two lateral communication passages (61b)
extends from the other end (an end toward the base (56)) of the longitudinal communication
passage (61a) to the outside in a radial direction of the rear shaft portion (58b),
and is opened at the outer peripheral surface of the rear shaft portion (58b).
[0095] The oil sump (62) is formed between the coupling portion (52) coupling base ends
of the gate rotor (50) and the base (56), of the support member (55), corresponding
to the coupling portion (52). Specifically, a space defined by a groove (62a) formed
in the coupling portion (52) of the gate rotor (50) and a groove (62b) formed in the
base (56) of the support member (55) is configured as the oil sump (62). The groove
(62a) in the gate rotor (50) and the groove (62b) in the support member (55) are formed
in an annular shape. The groove (62b) formed in the base (56) of the support member
(55) is in an annular shape to surround the outer periphery of the rear shaft portion
(58b), and is opened at the front surface of the base (56) facing the gate rotor (50).
The two lateral communication passages (61b) of the in-shaft communication passage
(61) are opened in the groove (62b). This configuration allows the oil sump (62) to
communicate with the oil sump (94c) of the first bearing holder (94) above the rear
shaft portion (58b) via the in-shaft communication passage (61).
[0096] The gate-side oil supply passages (63) are respectively formed in the gates (51)
of the gate rotor (50). In this embodiment, the gate-side oil supply passages (63)
are formed in all of the eleven gates (51). Each of the gate-side oil supply passages
(63) includes a body (53), a plurality of lateral branches (54), and a front branch
(59).
[0097] Specifically, as shown in FIG. 9, grooves (63a) extending in the radial direction
of the gate rotor (50) are formed in the rear surfaces of the gates (51). The grooves
(63a) are closed by front surfaces of the arms (57) respectively supporting the gates
(51) from the rear side. Space in each of the grooves (63a) closed by the front surfaces
of the arms (57) constitutes the body (53) of each of the gate-side oil supply passages
(63). As shown in FIG. 7, the body (53) of each gate-side oil supply passage (63)
extends radially from the base end to distal end of the gate (51). A base end of the
body (53) is connected to the oil sump (62) formed between the coupling portion (52)
coupling the base ends of the gates of the gate rotor (50) and the base (56) of the
support member (55).
[0098] As shown in FIGS. 7 and 8, the lateral branches (54) are formed by holes extending
from the body (53) of the gate (51) in the circumferential direction of the gate rotor
(50), and are connected to lateral oil supply ports (63b) which are opened at the
side surfaces (51a, 51b) of the gate (51). The lateral oil supply ports (63b) constitute
oil supply ports (4) for supplying the lubricant to the side surfaces (51a, 51b),
which are the sliding surfaces (3), of the gate (51). In this embodiment, each of
the gates (51) is provided with four lateral branches (54) on the front side, and
four lateral branches (54) on the rear side, in the rotation direction thereof. Thus,
in this embodiment, four lateral oil supply ports (63b) are opened at the front side
surface (51a) in the rotation direction of the gate (51), and four lateral oil supply
ports (63b) are opened at the rear side surface (51b). The four lateral oil supply
ports (63b) at the front side surface (51a) and the four oil supply ports (63b) at
the rear side surface (51b) are provided at positions corresponding to each other.
The four lateral oil supply ports (63b) at each side surface (51a, 51b) are arranged
at substantially equal intervals from the base end to distal end of the gate (51).
The diameter of each of the lateral oil supply ports (63b) and lateral branches (54)
is determined so that the lubricant flows in such an amount that allows an oil film
to be formed on the side surfaces (51a, 51b) of the gates (51), and that the lubricant
is kept from scattering in the shape of droplets.
[0099] The number of lateral oil supply ports (63b) and lateral branches (54) is not limited
to four, but may be less than four, or more than four. In a preferred embodiment,
the diameter is changed in accordance with the number so that the lubricant flows
in such an amount that allows an oil film to be formed on the side surfaces (51a,
51b) of the gates (51), and that the lubricant is kept from scattering in the shape
of droplets.
[0100] As shown in FIG. 8, each of the side surfaces (51a, 51b) of the gate (51) which slides
on the screw rotor (40) protrudes at a center portion in the thickness direction of
the gate. Each of the protruding center portion forms a seal line (L1, L2) which abuts
on the corresponding lateral face (42a, 42b) of the helical groove (41) of the screw
rotor (40). The lateral oil supply ports (63b) are opened at the side surfaces (51a,
51b) of each gate (51) at a position forward of the seal line (L1, L2), that is, toward
the compression chamber (23).
[0101] In this configuration, each of the gate-side oil supply passages (63) is connected
to the lateral oil supply ports (63b) opened at the side surfaces (51a, 51b) of the
gate (51) which slide on the screw rotor (40).
[0102] As shown in FIGS. 7 to 9, the front branch (59) is a hole which extends in a thickness
direction of the gate (51) (a direction parallel to the axial direction of the gate
rotor (50)) from the groove (63a) (body (53)) extending in the radial direction of
the gate rotor (50) of the gate (51), and is opened at the front surface (51c). The
front branch (59) is connected to a front oil supply port (63c) opened at the front
surface (51c) of the gate (51). The front oil supply port (63c) constitutes an oil
supply port (4) for supplying the lubricant to the front surface (51c), which is the
sliding surface (3), of the gate (51). In this embodiment, the front branch (59) is
provided for each of the plurality of gates (51). Thus, in this embodiment, a single
front oil supply port (63c) is opened at each of the front surfaces (51c) of the gates
(51). In this embodiment, each of the front oil supply ports (63c) is opened at a
position further inward than the center of the front surface (51c) of the gate (51)
in the radial direction. The diameter of each of the front oil supply ports (63c)
and front branches (59) is determined so that the lubricant flows in such an amount
that allows an oil film to be formed on the front surfaces (51c) of the gates (51),
and that the lubricant is kept from scattering in the shape of droplets. The number
of front oil supply ports (63c) and front branches (59) is not limited to one, but
may be two or more. In a preferred embodiment, the diameter is changed in accordance
with the number so that the oil film is formed on the front surfaces (51c) of the
gates (51).
[0103] In this configuration, each of the gate-side oil supply passages (63) is connected
to the front oil supply port (63c) opened at the front surface (51c) of the gate (51)
facing the compression chamber (23).
[0104] As described above, in the left oil supply mechanism (60), the in-shaft communication
passage (61), the oil sump (62), and the plurality of gate-side oil supply passages
(63), which are formed in the gate rotor (50) and the support member (55), form a
lubricant passage which is branched to have two or more outlets. The lubricant passage
has an inlet which is opened in the oil sump (94c) of the first bearing holder (94)
in which the high pressure lubricant flowing from the oil reservoir chamber (16b)
is accumulated. Although some of the plurality of lateral oil supply ports (63b) and
the front oil supply port (63c), which are the outlets of the lubricant passage, are
opened in the compression chamber (23), most of them are opened in the gate rotor
chamber (90) communicating with the low-pressure space (S1). Therefore, due to the
pressure difference between the inlet and outlets of the lubricant passage, the high
pressure lubricant in the oil sump (95c) enters the lubricant passage, flows toward
the outlets, and then flows to the side surfaces (51a, 51b) and front surface (51c)
of each gate (51).
-Operation-
[0105] When the electric motor (15) of the single-screw compressor (1) is actuated, the
drive shaft (21) rotates, and the screw rotor (40) rotates as well. As the screw rotor
(40) rotates, the gate rotor (50) also rotates, and the compression mechanism (20)
repeats a suction phase, a compression phase, and a discharge phase. In the following
description, the operation of the screw compressor (1) will be described, focusing
on the compression chamber (23) dotted in FIGS. 10A to 10C.
[0106] The compression chamber (23) dotted in FIG. 10A communicates with the low-pressure
space (S1). In this state, the gate (51) of the lower gate rotor (50) in FIG. 10A
meshes with the corresponding helical groove (41) which defines the compression chamber
(23). When the screw rotor (40) rotates, the gate (51) relatively moves within the
helical groove (41) toward the terminal end of the helical groove (41), causing the
capacity of the compression chamber (23) to gradually increase. As a result, the low
pressure gas refrigerant in the low-pressure space (S1) is sucked into the compression
chamber (23) through the suction port (24).
[0107] When the screw rotor (40) further rotates, the operation enters the state of FIG.
10B. The compression chamber (23) dotted in FIG. 10B is fully closed. In this state,
the gate (51) of the upper gate rotor (50) in FIG. 10B meshes with the corresponding
helical groove (41) which defines the compression chamber (23), and the compression
chamber (23) is partitioned from the low-pressure space (S1) by the gate (51). As
the screw rotor (40) rotates, the gate (51) relatively moves within the helical groove
(41) toward the terminal end of the helical groove (41), causing the capacity of the
compression chamber (23) to gradually decrease. As a result, the low pressure gas
refrigerant in the compression chamber (23) is gradually compressed.
[0108] When the screw rotor (40) further rotates, the operation enters the state of FIG.
10C. The compression chamber (23) dotted in FIG. 10C communicates with the high-pressure
space (S2) through the discharge port (25). In this state, when the gate (51) moves
within the helical groove (41) toward the terminal end of the helical groove (41)
with the rotation of the screw rotor (40), the compressed, high pressure refrigerant
gas (high pressure gas refrigerant) is pushed out of the compression chamber (23)
to the high-pressure space (S2).
[0109] When the above operation is performed, the capacity of the compression mechanism
(20) is controlled using the slide valve (70). Although not specifically described,
when pushed to the leftmost position in FIG. 2, the slide valve (70) comes to the
end where the slide valve (70) is fully closed (suction side). In this state, the
capacity of the compression mechanism (20) is maximized. When the slide valve (70)
moves back to the right in FIG. 3, the tip end face of the slide valve (70) releases
the axial gap (G), and the bypass passage (33) opens at the inner peripheral surface
of the cylindrical wall (30). Then, a portion of the refrigerant gas sucked into the
compression chamber (23) from the low-pressure space (S1) returns to the low-pressure
space (S1) from the compression chamber (23) in the course of the compression phase
via the bypass passage (33), and the rest of the refrigerant gas is compressed until
the end of the compression phase and discharged to the high-pressure space (S2). Thus,
the capacity of the compression mechanism (20) decreases.
-Oil Supply Operation-
[0110] In this manner, when the screw rotor (40) and the two gate rotors (50) rotate to
compress the refrigerant gas in the compression chamber (23), the two oil supply mechanisms
(60) supply the lubricant to the sliding surfaces (3) of the two gate rotors (50)
and the screw rotor (40).
[0111] In the two oil supply mechanisms (60), as described above, the pressure difference
between the inlet and outlets of the lubricant passage formed by the in-shaft communication
passage (61), the oil sump (62), and the plurality of gate-side oil supply passages
(63) causes the lubricant supplied to each oil sump (94c, 95c) from the oil reservoir
chamber (16b) to enter the lubricant passage, and flow toward the outlets. Specifically,
the lubricant in the oil sump (94c, 95c) flows into the longitudinal communication
passage (61a) of the in-shaft communication passage (61) inside the front shaft portion
(58a), diverges from the longitudinal communication passage (61a) to the two lateral
communication passages (61b), and eventually flows into the oil sump (62) (see FIGS.
5, 6, and 9). The lubricant that has reached the oil sump (62) flows into the plurality
of gate-side oil supply passages (63) extending radially from the oil sump (62) by
the effect of the driving force caused by the pressure difference described above
and the centrifugal force generated by the rotation of the gate rotor (50) and the
support member (55), and then flows radially outward in each of the gate-side oil
supply passages (63) (see FIGS. 5 and 9). The lubricant flowing through the gate-side
oil supply passages (63) flows to the side surfaces (51a, 51b) of the gate (51) from
the plurality of lateral oil supply ports (63b), and to the front surface (51c) of
the gate (51) from the front oil supply port (63c).
[0112] From the lateral oil supply ports (63b) of each gate (51), the lubricant flows in
such an amount that allows an oil film to be formed on the side surfaces (51a, 51b)
of the gate (51). The lubricant that has flowed from the plurality of lateral oil
supply ports (63b) is spread radially outward on the side surfaces (51a, 51b) of the
gates (51) by the effect of the centrifugal force to form the oil film on each of
the side surfaces (51a, 51b).
[0113] As described above, as shown in FIG. 8, the lateral oil supply ports (63b) are opened
at each of the side surfaces (51a, 51b) of the gate (51) at a position forward of
the seal line (L1, L2) which abuts on the corresponding lateral face (42a, 42b) of
the helical groove (41) of the screw rotor (40), that is, further toward the compression
chamber (23) than the seal line. Since the lateral oil supply ports (63b) are provided
at such positions, the lubricant is supplied to a portion of the side surface (51a,
51b) forward of the seal line (L1, L2) of each gate (51) in the traveling direction
of the gate (51) when the gate travels toward the compression chamber (23) in the
helical groove (41) of the screw rotor (40). As a result, the lubricant is reliably
supplied to the seal line (L1, L2) of each gate (51) which slides on the corresponding
lateral face (42a, 42b) of the helical groove (41) of the screw rotor (40). This can
lubricate the seal line (L1, L2), and achieve sealing at the seal line. This keeps
the gas refrigerant in the high pressure compression chamber (23) from leaking from
the gap between the side surface (51a, 51b) of the gate (51) and the lateral face
(42a, 42b) of the helical groove (41) of the cylindrical wall (30) to the low pressure
compression chamber (23).
[0114] In this manner, the lubricant that has flowed from the lateral oil supply ports (63b)
to the side surfaces (51a, 51b) of the gates (51) and supplied to the sliding surfaces
(3) of the screw rotor (40) adheres to the screw rotor (40), and is spread to the
outer periphery of the screw rotor by the effect of the centrifugal force generated
by the rotation of the screw rotor (40). As a result, an oil film is formed on the
outer peripheral surface (43) of the screw rotor (40) between the helical grooves
(41), and the outer peripheral surface (43) and the inner peripheral surface (30a)
of the cylindrical wall (30) are lubricated and the gap between them is sealed. This
keeps the screw rotor (40) from seizing, and blocks the gas refrigerant in the high
pressure compression chamber (23) from leaking to the low pressure compression chamber
(23) through the gap between the outer peripheral surface (43) of the screw rotor
(40) and the inner peripheral surface (30a) of the cylindrical wall (30).
[0115] On the other hand, the lubricant flows from the front oil supply port (63c) of each
of the gates (51) in such an amount that allows an oil film to be formed on the front
surface (51c) of the gate (51). The lubricant that has flowed from the front oil supply
port (63c) is spread radially outward on the front surface (51c) of the gate (51)
by the effect of the centrifugal force to form an oil film on the front surface (51c).
As described above, each of the front oil supply ports (63c) is opened at a position
inward of the center of the front surface (51c) of each gate (51) in the radial direction
(see FIG. 7). Therefore, the lubricant that has flowed from the front oil supply port
(63c) on the front surface (51c) of the gate (51) is spread widely outward from the
radially inward position.
[0116] The rotation of the gate rotor (50) causes each of the gates (51) to come in and
out of the cylindrical wall (30) via the opening (39) of the cylindrical wall (30).
As described above, the lubricant flowed from the front oil supply port (63c) is widely
spread over the front surface (51c) of each gate (51), and is supplied between the
front surface (51c) of the gate (51) and the sealing surface (39a) of the cylindrical
wall (30) facing each other. Thus, the lubricant lubricates the front surface (51c)
of the gate (51) and the sealing surface (39a) of the cylindrical wall (30), which
are the sliding surfaces, and seals a gap therebetween. This keeps the gates (51)
from seizing, and blocks the gas refrigerant in the high pressure compression chamber
(23) from leaking to the gate rotor chamber (90) through the gap between the front
surface (51c) of the gate (51) and the sealing surface (39a) of the cylindrical wall
(30).
-Advantages of First Embodiment-
[0117] According to the first embodiment, each of the gates (51) of the gate rotor (50)
is provided with the gate-side oil supply passage (63) directly supplying the lubricant
to the side surfaces (51a, 51b) which slide on the screw rotor (51) and need to be
lubricated and sealed by the lubricant. Thus, as compared to the conventional configuration
in which the lubricant is injected into the helical groove (41) to be indirectly supplied
to the sliding surfaces (3) of the gate rotor (50) and the screw rotor (40), the lubricant
can be reliably supplied to the sliding surfaces (3) of the gate (51) and the screw
rotor (40) in a smaller amount, thereby lubricating the gate (51) and the screw rotor
(40) and sealing the gap therebetween. Moreover, the lubricant supplied in this manner
to the sliding surfaces (3) of the screw rotor (40) and the gate (51) also adheres
to the screw rotor (40), and is spread toward the outer periphery of the screw rotor
(40) by the effect of the centrifugal force generated by the rotation of the screw
rotor (40). Thus, the lubricant can also be supplied to a gap between the screw rotor
(40) and the cylindrical wall (30) to seal the gap.
[0118] As described above, in the present embodiment, the efficiency of the compressor is
not lowered because it is unnecessary to increase the power for the transport of the
lubricant and the power for the rotation of the screw rotor (40), unlike the conventional
configuration in which a large amount of lubricant is supplied. Directly supplying
the lubricant in a small amount to the sliding surfaces (3) of the gate (51) and the
screw rotor (40) makes it possible to lubricate the gate (51) and the screw rotor
(40), and the screw rotor (40) and the cylindrical wall (30), and to seal the gap
between the gate (51) and the screw rotor (40), and the gap between the screw rotor
(40) and the cylindrical wall (30). That is, according to this embodiment, the gate
rotor (50) and the screw rotor (40) can be protected from the sliding wear, and a
high pressure fluid can be blocked from leaking from the compression chamber, even
if the supply amount of the lubricant is reduced. Therefore, in the present embodiment,
the supply amount of the lubricant can be reduced without lowering the reliability
of the single-screw compressor (1), which can improve the compressor efficiency.
[0119] According to the present embodiment, the gate-side oil supply passage (63) of the
gate (51) is provided with not only the lateral oil supply ports (63b) which are opened
at the side surfaces (51a, 51b) that slide on the screw rotor (40) of the gate (51),
but also the front oil supply port (63c) which is opened at the front surface (51c)
of the gate (51). Therefore, in the gate (51) of the gate rotor (50), the lubricant
in the gate-side oil supply passage (63) can be supplied not only to the side surfaces
(51a, 51b) that slide on the screw rotor (40), but also to the front surface (51c)
that faces the compression chamber (23). As a result, the lubricant is supplied between
the front surface (51c) of the gate (51) sliding on the surface of the cylindrical
wall (30), which lubricates these sliding surfaces, and seals a gap between them.
This can keep the seizing caused by the sliding movement of the gate (51), and can
block the fluid from leaking from the high pressure compression chamber (23) through
the gap between the front surface (51c) of the gate (51) and the cylindrical wall
(30) to the low-pressure space outside the cylindrical wall (30) where the gate rotor
(50) is disposed.
[0120] Further, in the present embodiment, the oil sump (62) is formed between the support
member (55) supporting the gate rotor (50) and the coupling portion (52) of the gate
rotor (50) coupling the base ends of the gates, and a base end of the gate-side oil
supply passage (63) in the gate (51) is connected to the oil sump (62). That is, the
gate-side oil supply passage (63) extends radially outward from the oil sump (62)
along the corresponding gate (51). In this configuration, the gate rotor (50) rotates
to generate the centrifugal force, which causes the lubricant in the oil sump (62)
to enter and flow radially outward through the gate-side oil supply passage (63) of
the gate (51), and flow from the lateral oil supply ports (63b). That is, this simple
configuration can supply the lubricant to the sliding surfaces (3) by utilizing the
centrifugal force generated by the rotation of the gate rotor (50).
<<Second Embodiment>>
[0121] In a second embodiment, the oil supply mechanism (60) and first and second bearing
holders (94, 95) of the single-screw compressor (1) of the first embodiment are partially
modified so that the lubricant is supplied intermittently as needed to the sliding
surfaces (3) of the gate rotors (50).
[Oil Supply Mechanism]
[0122] Specifically, as shown in FIGS. 11 and 12, the single-screw compressor of the second
embodiment has two oil supply mechanisms (60), each of which includes a plurality
of in-shaft communication passages (61), a plurality of oil sumps (62), and a plurality
of gate-side oil supply passages (63). In the second embodiment, eleven in-shaft communication
passages (61), eleven oil sumps (62), and eleven gate-side oil supply passages (63)
are provided.
[0123] As shown in FIG. 11, the right oil supply mechanism (60) includes a plurality of
in-shaft communication passages (61) formed inside the front shaft portion (58a).
As shown in FIG. 12, the left oil supply mechanism (60) includes a plurality of in-shaft
communication passages (61) formed inside the rear shaft portion (58b). Each of the
in-shaft communication passages (61) includes a longitudinal communication passage
(61a) and a lateral communication passage (61b), and is formed in an L-shape.
[0124] As shown in FIG. 11, each of the longitudinal communication passages (61a) in the
right oil supply mechanism (60) extends straight in the axial direction to pass through
an outer peripheral portion of the front shaft portion (58a) from one end to the other
end thereof. As shown in FIG. 12, each of the longitudinal communication passages
(61a) in the left oil supply mechanism (60) extends straight in the axial direction
to pass through an outer peripheral portion of the rear shaft portion (58b) from one
end to the other end thereof.
[0125] As shown in FIG. 11, each of the lateral communication passages (61b) in the right
oil supply mechanism (60) extends outward in the radial direction of the front shaft
portion (58a) from the other end (an end toward the base (56)) of an associated one
of the longitudinal communication passages (61a), and is opened at an outer peripheral
surface of the front shaft portion (58a). As shown in FIG. 12, each of the lateral
communication passages (61b) in the left oil supply mechanism (60) extends outward
in the radial direction of the rear shaft portion (58b) from the other end (an end
toward the base (56)) of an associated one of the longitudinal communication passages
(61a), and is opened at an outer peripheral surface of the rear shaft portion (58b).
[0126] Thus, in each of the oil supply mechanisms (60) of the second embodiment, the in-shaft
communication passages (61) are formed in the same number (eleven) as the gates (51)
to be in one-to-one correspondence with the eleven gates (51). In each oil supply
mechanism (60), the eleven in-shaft communication passages (61) are provided at equal
intervals in the circumferential direction of the front shaft portion (58a) or the
rear shaft portion (58b) so that each of the eleven lateral communication passages
(61b) extends in the direction of extension of the corresponding gate (51).
[0127] In each oil supply mechanism (60), the plurality of oil sumps (62) are formed between
a coupling portion (52) coupling base ends of the gates of the gate rotor (50) and
the base (56), of the support member (55), corresponding to the coupling portion (52).
Specifically, a plurality of grooves (62a) formed in the coupling portion (52) of
the gate rotor (50) and a plurality of grooves (62b) formed in the base (56) of the
support member (55) form a plurality of spaces, which respectively constitute the
oil sumps (62). The grooves (62a) of the gate rotor (50) and the grooves (62b) of
the support member (55) are formed in the same number (eleven) as the gates (51) to
be in one-to-one correspondence with the gates (51).
[0128] As shown in FIGS. 11 and 13, in the right oil supply mechanism (60), the eleven grooves
(62b) formed in the base (56) of the support member (55) extend radially outward from
the outer peripheral surface of the front shaft portion (58a), and are opened at the
front surface of the base (56) facing the gate rotor (50). As shown in FIGS. 12 and
13, in the left oil supply mechanism (60), the eleven grooves (62b) formed in the
base (56) of the support member (55) extend radially outward from the outer peripheral
surface of the rear shaft portion (58b), and are opened at the front surface of the
base (56) facing the gate rotor (50). In each oil supply mechanism (60), each of the
eleven lateral communication passages (61b) of the in-shaft communication passage
(61) is opened in an associated one of the grooves (62b).
[0129] In each oil supply mechanism (60), the gate-side oil supply passages (63) are respectively
formed in the gates (51) of the gate rotor (50). Also in the second embodiment, the
gate-side oil supply passages (63) are formed in all of the eleven gates (51). In
each of the oil supply mechanisms (60) of the second embodiment, the eleven gate-side
oil supply passages (63) are formed in one-to-one correspondence with the eleven oil
sumps (62). Each of the gate-side oil supply passages (63) includes a body (53), a
plurality of lateral branches (54), and a front branch (59).
[0130] Specifically, as shown in FIGS. 11 and 12, grooves (63a) extending in the radial
direction of each gate rotor (50) are formed in the rear surfaces of the gates (51).
The grooves (63a) formed in the gates (51) are formed in one to-one correspondence
with the eleven grooves (62a) formed in the coupling portion (52) of the gate rotor
(50), and are integrated with the corresponding grooves (62a). The grooves (63a) formed
in the gates (51) are closed by front surfaces of the arms (57) respectively supporting
the gates (51) from the rear side. Space in each of the grooves (63a) closed by the
front surfaces of the arms (57) constitutes the body (53) of each of the gate-side
oil supply passages (63). As shown in FIG. 13, the body (53) of each gate-side oil
supply passage (63) extends radially from a base end to distal end of the gate (51).
A base end of the body (53) is connected to the oil sump (62) formed between the coupling
portion (52) coupling the base ends of the gates of the gate rotor (50) and the base
(56), of the support member (55), corresponding to the coupling portion (52).
[0131] As shown in FIG. 13, in each of the oil supply mechanisms (60), the lateral branches
(54) are formed by holes extending from each body (53) of the gate (51) in the circumferential
direction of the gate rotor (50), and are connected to lateral oil supply ports (63b),
which are oil supply ports (4) opened at the side surfaces (51a, 51b) of the gate
(51). Also in the second embodiment, each of the gates (51) is provided with four
lateral branches (54) on the front side, and four lateral branches (54) on the rear
side, in the rotation direction thereof. Thus, also in the second embodiment, four
lateral oil supply ports (63b) are opened at the front side surface (51a) in the rotation
direction of the gate (51), and four lateral oil supply ports (63b) are opened at
the rear side surface (51b). The four lateral oil supply ports (63b) at the front
side surface (51a) and the four oil supply ports (63b) at the rear side surface (51b)
are provided at positions corresponding to each other. The four lateral oil supply
ports (63b) at each side surface (51a, 51b) are arranged at substantially equal intervals
from the base end to distal end of the gate (51). The diameter of each of the lateral
oil supply ports (63b) and lateral branches (54) is determined so that the lubricant
flows in such an amount that allows an oil film to be formed on the side surfaces
(51a, 51b) of the gates (51), and that the lubricant is kept from scattering in the
shape of droplets.
[0132] The number of lateral oil supply ports (63b) and lateral branches (54) is not limited
to four, but may be less than four, or more than four. In a preferred embodiment,
the diameter is changed in accordance with the number so that the lubricant flows
in such an amount that allows an oil film to be formed on the side surfaces (51a,
51b) of the gates (51), and that the lubricant is kept from scattering in the shape
of droplets.
[0133] Also in the second embodiment, as shown in FIG. 8, each of the side surfaces (51a,
51b) of the gate (51) which slides on the screw rotor (40) protrudes at a center portion
in the thickness direction of the gate. Each of the protruding center portion forms
a seal line (L1, L2) which abuts on the corresponding lateral face (42a, 42b) of the
helical groove (41) of the screw rotor (40). The lateral oil supply ports (63b) are
opened at the side surfaces (51a, 51b) of each gate (51) at a position forward of
the seal line (L1, L2), that is, toward the compression chamber (23).
[0134] In this configuration of the second embodiment, each of the gate-side oil supply
passages (63) in the oil supply mechanisms (60) is connected to the lateral oil supply
ports (63b) opened at the side surfaces (51a, 51b) of the gate (51) which slide on
the screw rotor (40).
[0135] As shown in FIGS. 11, 12, and 8, the front branch (59) of the second embodiment is
a hole which extends in a thickness direction of the gate (51) (a direction parallel
to the axial direction of the gate rotor (50)) from the groove (63a) (body (53)) extending
in the radial direction of the gate rotor (50) of the gate (51), and is opened at
the front surface (51c). The front branch (59) is connected to a front oil supply
port (63c) which is the oil supply port (4) opened at the front surface (51c) of the
gate (51). Also in the second embodiment, the front branches (59) are respectively
provided for the plurality of gates (51), and thus, a single front oil supply port
(63c) is opened at each of the front surfaces (51c) of the gates (51). Each of the
front oil supply ports (63c) is opened at a position further inward than the center
of the front surface (51c) of the gate (51) in the radial direction. Also in the second
embodiment, the diameter of each of the front oil supply ports (63c) and front branches
(59) is determined so that the lubricant flows in such an amount that allows an oil
film to be formed on the front surfaces (51c) of the gates (51), and that the lubricant
is kept from scattering in the shape of droplets. The number of front oil supply ports
(63c) and front branches (59) is not limited to one, but may be two or more. In a
preferred embodiment, the diameter is changed in accordance with the number so that
the oil film is formed on the front surfaces (51c) of the gates (51).
[0136] In this configuration of the second embodiment, the gate-side oil supply passages
(63) in each of the oil supply mechanisms (60) are connected to the front oil supply
ports (63c) each of which is opened at the front surface (51c) of the gate (51) facing
the compression chamber (23).
[0137] Thus, in each of the oil supply mechanisms (60) of the second embodiment, the plurality
of in-shaft communication passages (61), the plurality of oil sumps (62), and the
plurality of gate-side oil supply passages (63), which are formed in the gate rotor
(50) and the support member (55), form a plurality of lubricant passages.
[Bearing Holder]
[0138] As shown in FIGS. 11 and 12, in the second embodiment, each of the first and second
bearing holders (94, 95) has a tubular portion (94a, 95a) having a cylindrical shape
and a closed bottom, a flange (94b, 95b) formed around a base end of the tubular portion
(94a, 95a), and a closing portion (94d, 95d). The tubular portions (94a, 95a) and
the flanges (94b, 95b) are configured in the same manner as those of the first embodiment.
[0139] As shown in FIG. 11, in the right oil supply mechanism (60), the closing portion
(95d) of the second bearing holder (95) protrudes downward from an inner bottom surface
of the tubular portion (95a), and abuts on a top surface of the front shaft portion
(58a) of the support member (55) by a lower end thereof, thereby closing inlets of
some of the eleven in-shaft communication passages (61) (inlets of the longitudinal
communication passages (61a)) formed inside the front shaft portion (58a) of the support
member (55). As shown in FIG. 12, in the left oil supply mechanism (60), the closing
portion (94d) of the first bearing holder (94) protrudes downward from an inner bottom
surface of the tubular portion (94a), and abuts on a top surface of the rear shaft
portion (58b) by a lower end thereof, thereby closing inlets of some of the eleven
in-shaft communication passages (61) (inlets of the longitudinal communication passages
(61a)) formed inside the rear shaft portion (58b) of the support member (55).
[0140] In the second embodiment, as shown in FIG. 14, in each of the oil supply mechanisms
(60), the closing portion (94d, 95d) of the bearing holder (194, 95) is configured
to keep four of the inlets (61a-1 to 61a-11) of the eleven in-shaft communication
passages (61) in the front shaft portion (58a) or the rear shaft portion (58b) closer
to the screw rotor (40) open, and close the remaining seven inlets. With the closing
portion (94d, 95d) formed in this manner, the oil sump (94c, 95c) formed in each of
the first and second bearing holders (94, 95) is formed to have a wider portion on
the side closer to the screw rotor (40), and a narrower portion on the other side.
[0141] Note that the front shaft portion (58a) or the rear shaft portion (58b) in which
the in-shaft communication passages (58) are formed rotates in accordance with the
rotation of the gate rotors (50), but the closing portion (94d, 95d) is fixed and
does not rotate. Therefore, the inlets (61a-1 to 61a-11) of the in-shaft communication
passages (61) to be closed by the closing portions (94d, 95d) change in accordance
with the rotational angle position of the gate rotor (50).
[0142] For example, when the gate rotor (50) is at the rotational angle position shown in
FIG. 14, the closing portion (94d, 95d) closes the fifth to eleventh inlets (61a-5
to 61a-11), while keeping the first to fourth inlets (61a-1 to 61a-4) open. Thus,
the first to fourth inlets (61a-1 to 61a-4) are opened to the oil sump (94c, 95c).
When the gate rotor (50) moves in the direction of the arrow and its rotational angle
position changes, the closing portion (94d, 95d) closes the fourth to tenth inlets
(61a-4 to 61a-10), while keeping the first to third inlets (61a-1 to 61a-3) and the
eleventh inlet (61a-11) open. Thus, the first to third inlets (61a-1 to 61a-3) and
the eleventh inlet (61a-11) are opened in the oil sump (94c, 95c). As described above,
in the second embodiment, the inlets (61a-1 to 61a-11) of the in-shaft communication
passage (61) to be closed by the closing portion (94d, 95d) sequentially change as
the rotational angle position of the gate rotor (50) changes.
[0143] The in-shaft communication passage (61) whose inlet is closed by the closing portion
(94d, 95d) is blocked from the oil sump (94c, 95c). Thus, no lubricant flows into
this in-shaft communication passage from the oil sump (94c, 95c). Thus, no lubricant
flows into the oil sump (62) and the gate-side oil supply passage (63) which are sequentially
connected to the in-shaft communication passage (61) whose inlet is closed. That is,
the oil sump (94c, 95c), which is the oil supply source supplying the lubricant to
the gate-side oil supply passage (63), is blocked from the gate-side oil supply passage
(63). This brings the gate-side oil supply passage (63) into the non-supply state
in which no lubricant is supplied to the side surfaces (51a, 51b) and front surface
(51c) of the gate (51), which are the sliding surfaces (3) of the gate rotor (50).
On the other hand, the lubricant in the oil sump (94c, 95c) flows into the in-shaft
communication passage (61) whose inlet is not closed by the closing portion (94d,
95d) and is opened in the oil sump (94c, 95c), and also into the oil sump (62) and
the gate-side oil supply passage (63) which are sequentially connected to the in-shaft
communication passage (61). That is, the oil sump (94c, 95c), which is the oil supply
source supplying the lubricant to the gate-side oil supply passage (63), communicates
with the gate-side oil supply passage (63). This brings the gate-side oil supply passage
(63) into the supply state in which the lubricant is supplied to the side surfaces
(51a, 51b) and front surface (51c) of the gate (51), which are the sliding surfaces
(3) of the gate rotor (50).
[0144] As can be seen, in the second embodiment, each of the oil supply mechanisms (60)
includes the in-shaft communication passages (61) and the oil sumps (62) which are
individually connected to the gate-side oil supply passages (63). Further, the closing
portion (94d, 95d) is provided to close some of the inlets (61a-1 to 61a-11) of the
in-shaft communication passages (11). The inlets (61a-1 to 61a-11) of the inter-shaft
communication passage (61) to be closed by the closing portion (94d, 95d) are changed
in accordance with the rotation of the gate rotor (50). In this configuration, when
the rotational angle position of the gate rotor (50) is in a predetermined angular
range A1 to A11, the gate-side oil supply passages (63) are in the supply state in
which the gate-side oil supply passages (63) communicate with the oil sump (94c, 95c)
and supply the lubricant to the sliding surfaces (3). When the rotational angle position
of the gate rotor (50) is out of the predetermined angular range A1 to A11, the gate-side
oil supply passages (63) are in the non-supply state in which the gate-side oil supply
passages (63) are blocked from the oil sump (94c, 95c) and supply no lubricant to
the sliding surfaces (3). Thus, in each of the oil supply mechanisms (60) configured
in this manner, the plurality of in-shaft communication passages (61), the plurality
of oil sumps (62), and the closing portion (94d, 95d) constitute a switching mechanism
(6) for switching the gate-side oil supply passages (63) between the supply state
and the non-supply state.
-Advantages of Second Embodiment-
[0145] According to the configuration of the second embodiment described above, the gate-side
oil supply passages (63) can be switched between the supply state in which the lubricant
is supplied from the gate-side oil supply passages (63) to the sliding surfaces (3),
and the non-supply state in which no lubricant is supplied from the gate-side oil
supply passages (63) to the sliding surfaces (3). Thus, in a situation where the sliding
surfaces (3) of the gate rotor (50) (in this embodiment, the side surfaces (51a, 51b)
and front surface (51c) of the gate (51)) provided with the lateral oil supply ports
(63b) and the front oil supply port (63c), which are the oil supply ports (4), are
not configured to slide constantly, the gate-side oil supply passages (63) can be
switched to the non-supply state to stop the supply of the lubricant to the sliding
surfaces (3) when the sliding surfaces do not slide and require no lubrication. Therefore,
according to the second embodiment, the lubricant can be reliably supplied to the
sliding surfaces (3) of the gate rotors (50), while reducing the supply amount of
the lubricant.
[0146] Specifically, for example, the switching mechanism (6) is configured to switch the
gate-side oil supply passage (63) formed in each gate (51) to the supply state when
the front surface (51c) of the gate (51) faces the sealing surface (39a) of the cylindrical
wall (30) and when the side surfaces (51b, 51c) of the gate (51) face the inner surface
(42) of the helical groove of the screw rotor (40), and to switch the gate-side oil
supply passage (63) to the non-supply state when the gate (51) does not face the cylindrical
wall (30) or the screw rotor (40). In this configuration, when the gate (51) slides
on the cylindrical wall (30) and the screw rotor (40), the sliding surfaces (3) can
be lubricated. When the gate (51) does not slide on the cylindrical wall (30) and
the screw rotor (40) and forms a gap between the gate (51) and the cylindrical wall
(30) and the screw rotor (40), the gap can be sealed. On the other hand, when the
gate (51) does not face the cylindrical wall (30) or the screw rotor (40), no lubricant
is supplied to the sliding surfaces (3) from the gate-side oil supply passages (63).
This can reduce the supply amount of the lubricant.
[0147] In the second embodiment, as described above, when the rotational angle position
of the gate rotor (50) is in the predetermined angular range A1 to A11, the switching
mechanism (6) switches the gate-side oil supply passages (63) to the supply state
in which the gate-side oil supply passages (63) communicate with the oil sump (95c,
94c) to supply the lubricant to the sliding surfaces (3). When the rotational angle
positions of the gate rotor (50) is out of the predetermined angular range A1 to A11,
the switching mechanism (6) switches the gate-side oil supply passages (63) to the
non-supply state in which the gate-side oil supply passages (63) are blocked from
the oil sump (95c, 94c) and supply no lubricant to the sliding surfaces (3). Such
a simple configuration of the second embodiment makes it possible to automatically
switch the gate-side oil supply passages (63) between the supply state and the non-supply
state while the gate rotor (50) makes a single rotation.
<<Third Embodiment>>
[0148] In a third embodiment, the single-screw compressor (1) of the first embodiment is
modified such that the oil supply mechanism (60) provided for each of the two gate
rotors (50) is provided for the screw rotor (40) which meshes with the two gate rotors
(50).
[Oil Supply Mechanism]
[0149] Specifically, as shown in FIG. 15, the single-screw compressor of the third embodiment
has the oil supply mechanism (60) which is formed inside the screw rotor (40) and
includes a plurality of axial passages (65) and a plurality of screw-side oil supply
passages (66) (oil supply passages (5)).
[0150] The plurality of axial passages (65) is formed at a position closer to the rotation
axis than the bottom faces (42c) of the helical grooves (41) of the screw rotor (40).
In the third embodiment, six axial passages (65) are formed, and are arranged at equal
intervals on an outer periphery of the rotation axis of the screw rotor (40). Each
axial passage (65) is formed by a hole extending in the direction of the rotation
axis inside the screw rotor (40). A discharge end (a right end in FIG. 2) of each
axial passage (65) is opened at an end face (right end face in FIG. 2) of the screw
rotor (40) on the discharge side. A suction end (a left end in FIG. 2) of each axial
passage (65) does not reach an end face (a left end face in FIG. 2) of the screw rotor
(40). The discharge end of each axial passage (65) is opened in a space where the
high pressure lubricant that has lubricated the bearing (36) of the bearing holder
(35) for rotatably supporting the drive shaft (21), for example, is accumulated. This
configuration causes the high pressure lubricant to flow into the plurality of axial
passages (65), and causes the axial passages (65) to serve as oil sumps in which the
high pressure lubricant is accumulated.
[0151] The plurality of screw-side oil supply passages (66) is formed such that at least
one screw-side oil supply passage (66) extends from an associated one of the axial
passages (65) toward the outer periphery of the screw rotor (40). Each of the screw-side
oil supply passages (66) includes a body (66a) and a plurality of lateral branches
(66b).
[0152] More specifically, as shown in FIG. 15, the body (66a) of each of the screw-side
oil supply passages (66) is formed by a hole extending from an associated one of the
axial passages (65) toward the outer periphery of the screw rotor (40). In the third
embodiment, the body (66a) of the screw-side oil supply passage (66) extends to an
outer peripheral surface (43) which helically extends between the helical grooves
(41) of the screw rotor (40), and is opened at the outer peripheral surface (43).
That is, the body (66a) of the screw-side oil supply passage (66) is connected to
an outer peripheral oil supply port (66c) which is an oil supply port (4) opened at
the outer peripheral surface (43) of the screw rotor (40).
[0153] The lateral branches (66b) are formed by holes extending from the body (66a) toward
the lateral faces (42a, 42b) of the helical groove (41), and are connected to groove's
lateral oil supply ports (66d) (in-groove oil supply ports), which are the oil supply
ports (4) opened at the lateral faces (42a, 42b) of the helical grooves (41). In this
embodiment, two lateral branches (66b) are connected to a front portion and rear portion
in the rotation direction of the body (66a) of each of the screw-side oil supply passages
(66). Thus, in this embodiment, at least two groove's lateral oil supply ports (66d)
are opened at the front lateral face (42a) of the inner surface (42) of the helical
groove (41) of the screw rotor (40) in the rotation direction, and two groove's lateral
oil supply ports (66d) are opened at the rear lateral face (42b). The diameter of
each of the groove's lateral oil supply ports (66d) and lateral branches (66b) is
determined so that the lubricant flows in such an amount that allows an oil film to
be formed on the lateral faces (42a, 42b) of the helical groove (41) of the screw
rotor (40), and that the lubricant is kept from scattering in the shape of droplets.
[0154] The number of groove's lateral oil supply ports (66d) and lateral branches (66b)
is not limited to two, but may be less than two, or more than two. In a preferred
embodiment, the diameter is changed in accordance with the number so that the lubricant
flows in such an amount that allows an oil film to be formed on the lateral faces
(42a, 42b) of the helical groove (41) of the screw rotor (40), and that the lubricant
is kept from scattering in the shape of droplets.
[0155] In this configuration, each of the screw-side oil supply passages (66) is connected
to the groove's lateral oil supply ports (66d) opened at the lateral faces (42a, 42b)
of the helical groove (41) of the screw rotor (40).
[0156] In a preferred embodiment, the screw-side oil supply passages (66) are positioned
such that the groove's lateral oil supply ports (66d) are opened in the compression
chamber (23) during the suction phase. Alternatively, the screw-side oil supply passages
(66) may be positioned such that the groove's lateral oil supply ports (66d) are opened
in the compression chamber (23) during the suction phase, and also in the compression
chamber (23) during the compression phase and the discharge phase.
[0157] As described above, in the oil supply mechanism (60) formed in the screw rotor (40),
the axial passages (65) and the screw-side oil supply passages (66) form a plurality
of lubricant passages, each of which is branched to have two or more outlets. Each
of the lubricant passages has an inlet which is opened in a space where the high pressure
lubricant that has lubricated the bearing (36), for example, is accumulated, and an
outlet which is opened at the outer peripheral surface (43) of the screw rotor (40)
and the lateral faces (42a, 42b) of the groove. Therefore, due to the pressure difference
between the inlet and outlets of the lubricant passage, the high pressure lubricant
near the inlet enters the lubricant passage, flows toward the outlet, and then flows
to the outer peripheral surface (43) of the screw rotor (40) and the lateral faces
(42a, 42b) of the helical groove (41).
-Operation-
[0158] How the fluid is compressed in the compression mechanism (20) is the same as in the
first embodiment, and the description thereof is not repeated. The oil supply operation
different from that of the first embodiment will be described below.
-Oil Supply Operation-
[0159] When the screw rotor (40) and the two gate rotors (50) rotate to compress the refrigerant
gas in the compression chamber (23), the oil supply mechanism (60) formed in the screw
rotor (40) supplies the lubricant to the sliding surfaces (3) of the two gate rotors
(50) and the screw rotor (40).
[0160] In the oil supply mechanism (60), as described above, the pressure difference between
the inlets and outlets of the lubricant passage formed by the axial passage (65) and
the screw-side oil supply passage (66) causes the high pressure lubricant that has
lubricated the bearing (36) and has been accumulated in a predetermined space to enter
the lubricant passage, and flow toward the outlets. Specifically, the high pressure
lubricant flows into the axial passages (65) serving as the oil sumps, flows into
the plurality of screw-side oil supply passages (66) extending from the axial passages
(65) toward the outer periphery by the effect of the driving force derived from the
pressure difference described above and the centrifugal force generated by the rotation
of the screw rotor (40), and then flows outward in the screw-side oil supply passages
(66) (see FIG. 15). The lubricant flowing through the screw-side oil supply passages
(66) flows from the outer peripheral oil supply ports (66c) to the outer peripheral
surface (43) of the screw rotor (40), and also flows from the groove's lateral oil
supply ports (66d) to the lateral faces (42a, 42b) of the helical grooves (41) of
the screw rotor (40).
[0161] The outer peripheral surface (43) of the screw rotor (40) provided with the helical
grooves (41) slides on the inner peripheral surface (30a) of the cylindrical wall
(30) covering the outer periphery of the screw rotor (40). Thus, lubrication is required
to keep the outer peripheral surface (43) of the screw rotor (40) and the inner peripheral
surface (30a) of the cylindrical wall (30) from seizing. On the other hand, when a
gap is formed between the outer peripheral surface (43) of the screw rotor (40) and
the inner peripheral surface (30a) of the cylindrical wall (30), the gap needs to
be sealed so that the high pressure fluid does not leak to the low pressure side.
[0162] In the third embodiment, the screw-side oil supply passages (66) are formed in the
screw rotor (40), and are connected to the outer peripheral oil supply ports (66c)
opened at the outer peripheral surface (43) of the screw rotor (40) which slides on
the cylindrical wall (30). In the screw rotor (40) configured in this manner, the
lubricant in the screw-side oil supply passages (66) flows from the outer peripheral
oil supply ports (66c) to the outer peripheral surface (43) of the screw rotor (40)
which slides on the inner peripheral surface (30a) of the cylindrical wall (30), thereby
lubricating the outer peripheral surface (43), or sealing the gap, if any, between
the outer peripheral surface (43) and the inner peripheral surface (30a) of the cylindrical
wall (30).
[0163] In the third embodiment, unlike the conventional configuration, the outer peripheral
oil supply ports (66c), which are the oil supply ports (4), are opened at the outer
peripheral surface (43) of the screw rotor (40) that rotates. Therefore, the lubricant
that has flowed from the outer peripheral oil supply ports (66c) is rapidly spread
over the rotating screw rotor (40), and is quickly supplied to the sliding surfaces
(3) other than the outer peripheral surface (43) at which the outer peripheral oil
supply ports (66c) are formed. Further, since the screw rotor (40) and the gate rotors
(50) mesh with each other and rotate together, the lubricant supplied to the screw
rotor (40) is rapidly spread to the gate rotors (50), and is quickly supplied to the
sliding surfaces (3) of the gate rotors (50).
[0164] In the third embodiment, the screw-side oil supply passages (66) are formed in the
screw rotor (40), and the oil supply passages (5) are connected to the groove's lateral
oil supply ports (66d), which are the in-groove oil supply ports opened at the inner
surface (42) of the helical groove (41) of the screw rotor (66). In the screw rotor
(40) configured in this manner, the lubricant in the screw-side oil supply passages
(66) flows from the groove's lateral oil supply ports (66d) to the lateral faces (42a,
42b) of the helical grooves (41) which slide on the gate rotor (50), thereby lubricating
the lateral faces (42a, 42b), or sealing the gap, if any, between the lateral faces
(42a, 42b) and the gate rotor (50) sliding on the lateral faces. That is, in the third
embodiment, unlike in the conventional configuration, the lubricant is directly supplied
to the lateral faces (42a, 42b), which are the sliding surfaces (3), from the groove's
lateral oil supply ports (66d) opened at the lateral faces (42a, 42b) of the helical
grooves of the screw rotor (40).
[0165] Further, in the third embodiment, unlike in the conventional configuration, the groove's
lateral oil supply ports (66d), which are the oil supply ports (4), are opened at
the lateral faces (42a, 42b) of the helical grooves of the screw rotor (40) that rotates.
Therefore, the lubricant which has flowed from the groove's lateral oil supply ports
(66d) is rapidly spread over the rotating screw rotor (40) by the effect of the centrifugal
force, and is quickly supplied to the sliding surfaces (3) other than the lateral
faces (42a, 42b) of the helical grooves. Further, the lubricant supplied to the lateral
faces (42a, 42b) of the helical groove of the screw rotor (40) also adheres to the
gate rotors (50) which mesh with and rotate with the screw rotor (40), and is rapidly
spread over the gate rotors (50) by the effect of the centrifugal force. Thus, the
lubricant is quickly supplied to the sliding surfaces (3) of the gate rotors (50).
-Advantages of Third Embodiment-
[0166] According to the configuration of the third embodiment described above, the screw-side
oil supply passages (66) serving as the oil supply passages (5) are formed in the
screw rotor (40), which is at least one of the screw rotor (40) and the gate rotors
(50) mesh with each other and rotate together, and the screw-side oil supply passages
(66) are connected to the outer peripheral oil supply ports (66c) and the groove's
lateral oil supply ports (66d), which are the oil supply ports (4) opened at the outer
peripheral surface (43) and the groove's lateral faces (42a, 42b). As a result, the
lubricant is directly supplied from the outer peripheral oil supply ports (66c) and
the groove's lateral oil supply ports (66d) to the outer peripheral surface (43) and
the lateral faces (42a, 42b) of the helical grooves, which are the sliding surfaces
(3). Therefore, as compared to the conventional configuration in which the lubricant
is injected from the oil supply port formed in the cylindrical wall to be indirectly
supplied to the inner surfaces (42) of the helical grooves of the screw rotor (40),
the lubricant can be reliably supplied in a smaller amount to the outer peripheral
surface (43) and the lateral faces (42a, 42b), which are the sliding surfaces (3)
of the screw rotor (40).
[0167] According to the third embodiment, unlike in the conventional configuration in which
the lubricant is injected from the oil supply port formed in the cylindrical wall
(30) which does not rotate, the outer peripheral oil supply ports (66c) and the groove's
lateral oil supply ports (66d), which are the oil supply ports (4), are opened at
the outer peripheral surface (43) and the lateral faces (42a, 42b) of the helical
grooves, which are the sliding surfaces (3) of the screw rotor (40) that rotates,
so that the lubricant flows to the sliding surfaces (3) from these oil supply ports.
Therefore, the lubricant that has flowed from the outer peripheral oil supply ports
(66c) and the groove's lateral oil supply ports (66d) is rapidly spread over the rotating
screw rotor (40), and can be quickly supplied to the sliding surfaces (3) other than
the outer peripheral surface (43) and the lateral faces (42a, 42b) of the helical
grooves at both of which the oil supply ports (4) are formed. Since the screw rotor
(40) and the gate rotors (50) mesh with each other and rotate together, the lubricant
supplied to the screw rotor (40) is rapidly spread to the gate rotors (50), and can
be quickly supplied to the sliding surfaces (3) of the gate rotors (50).
[0168] As described above, in the third embodiment, the efficiency of the compressor is
not lowered because it is unnecessary to increase the power for the transport of the
lubricant and the power for the rotation of the screw rotor (40), unlike the conventional
configuration in which a large amount of lubricant is supplied. Supplying the lubricant
in a small amount to at least one of the sliding surface (3) of the screw rotor (40)
or the sliding surface (3) of the gate rotor (50) makes it possible to lubricate the
sliding surface (3) of each of the screw rotor (40) and the gate rotor (50), or to
seal a gap, if any, between the sliding surface (3) and its counterpart sliding surface.
That is, according to the third embodiment, the sliding surfaces (3) of the screw
rotor (40) and the gate rotor (50) can be kept from seizing, and the high pressure
fluid can be blocked from leaking from the compression chamber, even if the supply
amount of the lubricant is reduced. Therefore, in the third embodiment, the supply
amount of the lubricant can be reduced without lowering the reliability of the screw
compressor (1), which can improve the compressor efficiency.
[0169] According to the third embodiment, the axial passages (65) serving as the oil sumps
are formed at a position closer to the rotation axis of the screw rotor (40) than
the bottom faces (42c) of the helical grooves (41), and base ends of the screw-side
oil supply passages (66) are respectively connected to the axial passages (65). That
is, the screw-side oil supply passages (66) extend from the axial passages (65) in
the screw rotor (40) toward the outer periphery. In this configuration, the screw
rotor (40) rotates to generate the centrifugal force, which causes the lubricant to
enter the screw-side oil supply passages (66) from the axial passages (65), flows
toward the outer periphery of the screw rotor (40), and flows from the oil supply
ports (4) (the outer peripheral oil supply ports (66c) and the groove's lateral oil
supply ports (66d)) to the sliding surfaces (3) of the screw rotor (40) (the outer
peripheral surface (43) and lateral faces (42a, 42b) of the helical grooves). That
is, this simple configuration can supply the lubricant to the sliding surfaces (3)
of the screw rotor (40) (the outer peripheral surface (43) and the lateral faces (42a,
42b) of the helical grooves) by utilizing the centrifugal force generated by the rotation
of the screw rotor (40).
<<Other Embodiments>>
[0170] In the first to third embodiments, the single-screw compressor provided in the refrigerant
circuit to compress the refrigerant has been described. However, a target to be compressed
(fluid) is not limited to the refrigerant, and the compressor is not limited to the
single-screw compressor. The compressor may be a twin screw compressor including a
male rotor and a female rotor, or a compressor including female rotors provided on
both sides of a male rotor.
[0171] The front oil supply ports (63c) that have been formed in the first and second embodiments
may not be formed. Alternatively, the lateral oil supply ports (63b) may be omitted,
and the gate-side oil supply passages (63) may be connected only to the front oil
supply ports (63c).
[0172] In the first and second embodiments, it has been described that the lateral oil supply
ports (63b) of each of the gate-side oil supply passages (63) are opened at the side
surfaces (51a, 51b) of the gate (51) on the front and rear sides in the direction
of rotation of the gate (51). However, the lateral oil supply ports (63b) may be opened
at least at the rear side surface (51b) of the gate (51), and no oil supply port may
be opened at the front side surface (51b) of the gate (51). The rear side surface
(51b) in the rotation direction of the gate (51) is the sliding surface (3) which
reliably slides on the screw rotor (40) and is pressed by the screw rotor (40), and
therefore, is probably worn through the sliding movement. However, the lateral oil
supply ports (63b) opened at the rear side surface (51b) cause the lubricant to be
reliably supplied between the rear side surface (51b) and the lateral face (42a, 42b)
of the helical groove (41). This can protect the gate (51) and the screw rotor (40)
from the sliding wear.
[0173] Similarly, in the third embodiment, the groove's lateral oil supply ports (66d) of
the screw-side oil supply passages (66) are opened at both lateral faces (42a, 42b)
of each of the helical grooves (41) of the screw rotor (40) on the front and rear
sides in the rotation direction of the screw rotor. However, the groove's lateral
oil supply ports (66d) may be opened at least at the lateral face (42b) on the rear
side of the helical groove (41) in the rotation direction, and no oil supply port
may be opened at the lateral face (42a) on the front side of the helical groove (41)
in the rotation direction. The rear lateral face (42b) of the helical groove (41)
in the rotation direction is the sliding surface (3) which reliably slides on the
gate (51) of the gate rotor (50) and presses the gate (51) of the gate rotor (50),
and therefore, is probably worn through the sliding movement. However, the groove's
lateral oil supply ports (66d) opened at the rear lateral face (42b) of the helical
groove (41) cause the lubricant to be reliably supplied between the rear lateral face
(42b) of the helical groove (41) and the gate (51) of the gate rotor (50). This can
protect the gate (51) of the gate rotor (50) and the screw rotor (40) from the sliding
wear.
[0174] Further, in the first and second embodiments, four lateral oil supply ports (63b)
are opened at each of the side surfaces (51a, 51b) of the gate (51) at substantially
equal intervals from the base end to distal end of the gate (51). However, it is not
always necessary to provide a plurality of lateral oil supply ports (63b) at equal
intervals, and at least one lateral oil supply port (63b) may be formed at a position
closer to the base end of the gate (51) than the center thereof in the radial direction.
The at least one lateral oil supply port (63b) opened at a position closer to the
base end of the gate (51) than the center thereof in the radial direction makes it
possible to supply the lubricant to the base end of the side surface (51a, 51b) of
the gate (51), and to easily spread the lubricant toward the distal end of the side
surface (51a, 51b) of the gate (51) by utilizing the centrifugal force. This configuration
can minimize the number of the lateral oil supply ports (63b), and can further reduce
the supply amount of the lubricant.
[0175] Similarly, in the third embodiment, two groove's lateral oil supply ports (66d) are
opened at each of the lateral faces (42a, 42b) of the helical grooves (41) of the
screw rotor (40). However, the two groove's lateral oil supply ports (66d) are not
always necessary, and at least one groove's lateral oil supply port may be formed
at each lateral face (42a, 42b) of the helical groove (41) at a position closer to
the bottom face (42c) of the helical groove (41) than to the outer peripheral surface
(43) of the screw rotor (40). The at least one groove's lateral oil supply port (66d)
opened at the lateral face (42a, 42b) of the helical groove (41) of the screw rotor
(40) at a position closer to the bottom face (42c) of the helical groove (41) than
to the outer peripheral surface (43) makes it possible to supply the lubricant to
a portion of the lateral face (42a) of the helical groove (41) closer to the rotation
axis, and to easily spread the lubricant to a portion of the lateral face (42a, 42b)
of the helical groove (41) closer to the outer peripheral surface (43) by utilizing
the centrifugal force. This configuration can minimize the number of the groove's
lateral oil supply ports (66d), and can further reduce the supply amount of the lubricant.
[0176] Further, in the first and second embodiments, the oil supply mechanism (60) having
the gate-side oil supply passage (63) has been provided in each of the two gate rotors
(50). However, the oil supply mechanism (60) may be provided in only one of the gate
rotors (50). When the oil supply mechanism (60) provided in one of the gate rotors
(50) supplies the lubricant to the sliding surfaces (3) of the gate rotor (50) and
the screw rotor (40), the lubricant adheres to the lateral faces (42a, 42b) of the
helical grooves (41) of the screw rotor (40). Thus, when the amount of the lubricant
that adheres to the lateral faces (42a, 42b) of the helical grooves (41) of the screw
rotor (40) is controlled, the lubricant can be left in the helical grooves (41) to
lubricate the sliding surfaces (3) of the other gate rotor (50) and the screw rotor
(40), and to seal the gap between the sliding surfaces (3).
[0177] In the first and second embodiments, the gate-side oil supply passages (63) of the
oil supply mechanism (60) are formed in all the gates (51) of the gate rotor (50).
However, the gate-side oil supply passage (63) may be formed in at least one of the
gates (51), and more preferably, may be formed in the same number as the number of
helical grooves (41) in the screw rotor (40) (six in the above-described embodiments)
in the gates (51) adjacent to each other. When the amount of lubricant supplied from
the gate-side oil supply passages (63) to the sliding surfaces (3) of the gate rotor
(50) and the screw rotor (40) is controlled by adjusting the number and diameter of
the lateral oil supply ports (63b), the sliding surfaces (3) of the gate rotor (50)
and the screw rotor (40) can be protected from the seizing even if the gate-side oil
supply passage (63) is not formed in every gate (51).
[0178] In the first and second embodiments, the right oil supply mechanism (60) in FIG.
3 has the in-shaft communication passage (61) formed inside the front shaft portion
(58a), and the left oil supply mechanism (60) has the in-shaft communication passage
(61) formed inside the rear shaft portion (58b). However, the position of the in-shaft
communication passage (61) is not limited thereto. The right oil supply mechanism
(3) in FIG. 3 may have the in-shaft communication passage (61) formed inside the rear
shaft portion (58b), and the left oil supply mechanism (60) may have the in-shaft
communication passage (61) formed inside the front shaft portion (58a). Alternatively,
both of the oil supply mechanisms (60) may have the in-shaft communication passage
(61) formed inside the front shaft portion (58a) or the rear shaft portion (58b).
[0179] In the third embodiment, the screw-side oil supply passages (66) are connected to
the outer peripheral oil supply ports (66c) opened at the outer peripheral surface
(43) of the screw rotor (40) and the groove's lateral oil supply ports (66d) opened
at the lateral faces (42a, 42b) of the helical grooves (41). However, the screw-side
oil supply passages (66) are not limited to those connected to the outer peripheral
oil supply ports (66c) and the groove's lateral oil supply ports (66d). For example,
the screw-side oil supply passages (66) may be connected to bottom oil supply ports
which are opened at the bottom faces (42c) of the helical grooves (41) of the screw
rotor (40). Alternatively, the screw-side oil supply passages (66) may be connected
only to the outer peripheral oil supply ports (66c) or the groove's lateral oil supply
ports (66d).
[0180] The switching mechanism (6) of the second embodiment is not limited to have the above-described
configuration, and may be configured in any way as long as the gate-side oil supply
passages (63) can be switched between the supply state and the non-supply state. Further,
the switching mechanism (6) of the second embodiment can be applied to the oil supply
mechanism (60) formed in the screw rotor (40) as described in the third embodiment.
In this case, a closing portion as described in the second embodiment may be provided
in a space in which the discharge ends of the plurality of axial passages (65) are
opened and the high pressure lubricant is accumulated.
[0181] The embodiments described above are merely exemplary ones in nature, and do not intend
to limit the scope of the present invention, applications, or use thereof.
INDUSTRIAL APPLICABILITY
[0182] As can be seen from the foregoing, the present invention is useful for a screw compressor.
DESCRIPTION OF REFERENCE CHARACTERS
[0183]
1 Single-Screw Compressor (Screw Compressor)
3 Sliding Surface
4 Oil Supply Port
5 Oil Supply Passage
6 Switching Mechanism
23 Compression Chamber
30 Cylindrical Wall (Rotor Casing)
39 Opening
40 Screw Rotor (First Rotor)
41 Helical Groove
42 Inner surface of Helical Groove (Sliding Surface)
42a Lateral Face of Helical Groove (Sliding Surface)
42b Lateral Face of Helical Groove (Sliding Surface)
43 Outer Peripheral Surface (Sliding Surface)
50 Gate Rotor (Second Rotor)
51 Gate
51a Front Side Surface (Side Surface, Sliding Surface)
51b Rear Side Surface (Side Surface, Sliding Surface)
51c Front Surface (Sliding Surface)
52 Coupling Portion
55 Support Member
63 Gate-side Oil Supply Passage (Oil Supply Passage)
63b Lateral Oil Supply Port (Oil Supply Port)
63c Front Oil Supply Port (Oil Supply Port)
65 Axial Passage (Oil Sump)
66 Screw-side Oil Supply Passage (Oil Supply Passage)
66c Outer Peripheral Oil Supply Port (Oil Supply Port)
66d Groove's Lateral Oil Supply Port (Oil Supply Port, In-Groove Oil Supply Port)