TECHNICAL FIELD
[0001] The present invention relates to a scroll compressor, and more particularly relates
to a measure to supply oil to a sliding portion of a compression mechanism.
BACKGROUND ART
[0002] Scroll compressors having a fixed scroll and a movable scroll for compressing a fluid
therebetween have been known and widely used in, e.g., a refrigerating apparatus.
[0003] Patent Document 1 discloses a scroll compressor of this type. The scroll compressor
has an electric motor housed in a casing, and a drive shaft driven in rotation by
the electric motor. One end of the drive shaft is engaged with an engaging portion
of an end plate of the movable scroll. The rotation of the drive shaft being driven
by the electric motor causes the movable scroll to rotate eccentrically relative to
the fixed scroll, which gradually reduces the volume of a compression chamber between
these scrolls, thereby compressing the fluid in the compression chamber.
[0004] Further, a housing which rotatably receives the drive shaft is fixed to the inner
peripheral surface of the casing. The housing has a receiving chamber, arranged in
its upper middle portion, for receiving the drive shaft and the engaging portion of
the movable scroll. An oil pump is provided at a lower end portion of the drive shaft
in order to suck up oil from an oil reservoir at the bottom of the casing. The oil
sucked up by the oil pump with the rotation of the drive shaft flows upward through
an oil passage in the drive shaft. The oil is then supplied to a bearing of the drive
shaft and the sliding portion between the drive shaft and the engaging portion of
the movable scroll, and thereafter into the receiving chamber. The oil accumulated
in the receiving chamber sequentially flows through an oil passage 44a extending radially
outward from the receiving chamber, and an oil passage 44b extending upward from the
outlet of the oil passage 44a, and is then supplied to a sliding portion (a sliding
portion of a thrust surface) of the compression mechanism. Thus, the scroll compressor
of Patent Document 1 lubricates the sliding portion of the thrust surface of the compression
mechanism, using the oil which has been used to lubricate the sliding portion between
the drive shaft and the engaging portion of the movable scroll.
[0005] Patent Document 2 discloses a scroll compressor having a sealed vessel divided into
a high pressure side, exposed to a compression chamber outlet, and a low pressure
side exposed to suction pressure. The compressor features a bearing structure having
a groove where lubricant oil is accumulated.
CITATION LIST
PATENT DOCUMENT
SUMMARY OF THE INVENTION
TECHNICAL PROBLEM
[0007] The scroll compressor disclosed in Patent Document 1 always needs to store a certain
amount of oil in the receiving chamber so that the oil in the receiving chamber can
be supplied to the sliding portion of the compression mechanism with reliability.
However, such storage of a certain amount of oil in the receiving chamber will cause
the drive shaft or engaging portion housed in the receiving chamber to be soaked in
the oil. This increases a frictional resistance between the drive shaft or the engaging
portion and the oil during the rotation of the drive shaft, thereby increasing churning
loss and the motive energy of the electric motor.
[0008] In view of the foregoing background, it is therefore an object of the present invention
to provide a scroll compressor that can reduce such oil churning loss in the receiving
chamber.
SOLUTION TO THE PROBLEM
[0009] A first aspect of the invention is directed to a scroll compressor including: a casing
(15); an electric motor (50) housed in the casing (15); a drive shaft (60) driven
by the electric motor (50); a compression mechanism (20) which has a movable scroll
(40) and a fixed scroll (30), the movable scroll (40) having an engaging portion (43),
with which one end of the drive shaft (60) engages, and rotating eccentrically relative
to the drive shaft (60); a housing (25) including a bearing (28) which supports the
drive shaft (60), and a receiving portion (26) which receives the engaging portion
(43); and an oil transfer mechanism (75) which transfers oil in an oil reservoir (18)
of the casing (15). The drive shaft (60) is provided with an oil supply passage (70)
which supplies the oil transferred by the oil transfer mechanism (75) to a sliding
portion (44) of the engaging portion (43). In this scroll compressor, the housing
(25) is provided with a recess (78) which is provided on a bottom (26a) of the receiving
portion (26), and in which the oil accumulates after lubricating the sliding portion
(44) of the engaging portion (43), and an oil supply channel (90) which delivers the
oil in the recess (78) to a sliding portion (35, 45) of the compression mechanism
(20), the recess (78) is configured as an annular groove (78) surrounding an entire
periphery of the bearing (28), the housing (25) is provided with a cylindrical projection
(79) between the annular groove (78) and the bearing (28), and the cylindrical projection
(79) elastically deforms along the drive shaft (60) when the drive shaft (60) warps
radially outward during rotation of the drive shaft (60).
[0010] In the first aspect of the invention, one end of the drive shaft (60) engages with
the engaging portion (43) of the movable scroll (40), thereby coupling the drive shaft
(60) and the movable scroll (40). Rotation of the drive shaft (60) being driven by
the electric motor (50) causes the movable scroll (40) to rotate eccentrically relative
to the fixed scroll (30), which reduces the volume of a compression chamber between
the fixed scroll (30) and the movable scroll (40), thereby compressing the fluid in
the compression chamber.
[0011] The oil transfer mechanism (75) supplies the oil in the oil reservoir (18) of the
casing (15) to the sliding portion (44) between the drive shaft (60) and the engaging
portion (43) via the oil supply passage (70). As a result, the sliding portion (44)
is lubricated with the oil to cause a decrease in sliding friction. The oil used to
lubricate the sliding portion (44) of the engaging portion (43) flows into the receiving
portion (26) that receives the engaging portion (43). Since the present invention
provides a recess (78) on the bottom of the receiving portion (26), the oil which
has flowed out falls down into the recess (78). This reduces the possibility of the
oil accumulating in the receiving portion (26) so much as to reach the vicinity of
the engaging portion (43). As a result, the oil churning loss is reduced at the engaging
portion (43) during its rotation.
[0012] The oil which has fallen down into the recess (78) is led to the sliding portion
(35, 45) of the compression mechanism (20) through the oil supply channel (90). Since
the recess (78) is located at a lower level than the bottom of the receiving portion
(26), the oil in the receiving portion (26) is successively supplied into the recess
(78). This allows for a reliable supply of the oil in the recess (78) to the sliding
portion (35, 45) of the compression mechanism (20).
[0013] Also in the first aspect of the invention, the recess (78) is configured as an annular
groove (78) surrounding an entire periphery of the bearing (28).
[0014] The recess of the first aspect is configured as an annular groove (78) surrounding
an entire periphery of the bearing (28) of the drive shaft (60). The annular groove
surrounding the entire periphery of the bearing (28) decreases the elastic modulus
of a portion of the housing (25) between the annular groove (78) and the bearing (28).
Thus, this portion is easily deformed along the outer peripheral surface of the drive
shaft (60) even if the axial center of the drive shaft (60) inclines during the rotation
of the drive shaft (60). This prevents the outer peripheral surface of the drive shaft
(60) from partially contacting with the bearing (28), thereby reducing bearing load
on the bearing (28).
[0015] A second aspect of the invention is an embodiment of the first aspect of the invention.
In the second aspect, the housing (25) is provided with an oil exhaust channel (80)
which delivers the oil in the receiving portion (26) to the oil reservoir (18).
[0016] In the second aspect of the invention, part of the oil which has fallen down into
the receiving portion (26) after lubricating the sliding portion (44) of the engaging
portion (43) returns to the oil reservoir (18) through the oil exhaust channel (80).
This prevents a shortage of oil in the oil reservoir (18). Further, a rise in the
oil level of the receiving portion (26) is prevented by returning the oil in the receiving
portion (26) to the oil reservoir (18) through the oil exhaust channel (80). Thus,
the engaging portion (43) is prevented from being soaked in the oil, which reduces
the oil churning loss at the engaging portion (43) during its rotation.
[0017] A third aspect of the invention is an embodiment of the second aspect of the invention.
In the third aspect, an inlet port (80a) of the oil exhaust channel (80) is opened
to an inner space of the receiving portion (26) so as to be level with the bottom
(26a) of the receiving portion (26).
[0018] In the third aspect of the invention, the inlet port (80a) of the oil exhaust channel
(80) is arranged to be level with the bottom (26a) of the receiving portion (26).
Thus, the oil which has overflowed from the recess (78) is immediately introduced
to the oil exhaust channel (80). The rise in the oil level in the receiving portion
(26) is therefore prevented with reliability.
[0019] A fourth aspect of the invention is an embodiment of the second aspect of the invention.
In the : fourth aspect, an inlet port (80a) of the oil exhaust channel (80) is opened
to inside of the recess (78).
[0020] In the: fourth aspect of the invention, part of the oil which has fallen down into
the recess (78) from the receiving portion (26) returns to the oil reservoir (18)
through the oil exhaust channel (80). Thus, the oil in the recess (78) is prevented
from overflowing into the receiving portion (26), thereby preventing the rise in the
oil level in the receiving portion (26) with reliability.
[0021] A fifth aspect of the invention is an embodiment of the fourth aspect of the invention.
In the fifth aspect, the inside of the recess (78) is partitioned, by a partition
member (100) extending from a bottom of the recess (78) to an open end of the recess
(78), into a first space (S1) which communicates with an inlet port (90a) of the oil
supply channel (90), and a second space (S2) which communicates with the inlet port
(80a) of the oil exhaust channel (80), and the first space (S1) has a larger volume
than the second space (S2).
[0022] In the fifth aspect of the invention, the inside of the recess (78) is partitioned
into a first space (S1) and a second space (S2) by a partition member (100). The volume
of the first space (S1) that communicates with the oil supply channel (90) is larger
than the volume of the second space (S2) that communicates with the oil exhaust channel
(80). This means that the amount of the oil falling down into the recess (78) after
having been used to lubricate the sliding portion (44) of the engaging portion (43)
is greater in the first space (S1) than in the second space (S2). Thus, the present
invention allows for storing a sufficient amount of oil to be supplied to the sliding
portion (35, 45) of the compression mechanism (20) through the oil supply channel
(90).
[0023] A sixth aspect of the invention is an embodiment of any one of the fourth or fifth
aspects of the invention. In the sixth aspect, the inlet port (90a) of the oil supply
channel (90) is located at a lower level than the inlet port (80a) of the oil exhaust
channel (80).
[0024] In the sixth aspect of the invention, the inlet port (90a) of the oil supply channel
(90) is located at a lower level than the inlet port (80a) of the oil exhaust channel
(80). Thus, if the oil level is between the inlet port (90a) of the oil supply channel
(90) and the inlet port (80a) of the oil exhaust channel (80), this oil is led only
to the oil supply channel (90). On the other hand, if the oil level is higher than
the inlet port (80a) of the oil exhaust channel (80), this oil is led to both of the
oil supply channel (90) and the oil exhaust channel (80). That is, according to the
present invention, the oil which has flowed out into the receiving portion (26) is
supplied preferentially to the oil supply channel (90) rather than to the oil exhaust
channel (80). This allows for reliable lubrication of the sliding portion (35, 45)
of the compression mechanism (20).
ADVANTAGES OF THE INVENTION
[0025] According to the present invention, the recess (78) is provided on the bottom (26a)
of the receiving portion (26). This allows for delivering the oil used to lubricate
the sliding portion (44) of the engaging portion (43) to the recess (78). As a result,
the possibility of the engaging portion (43) being soaked in the oil is reduced in
the receiving portion (26), thereby reducing the oil churning loss at the engaging
portion (43) during its rotation.
[0026] If the oil were agitated by the engaging portion (43), a compressed fluid could be
mixed with this oil, or the oil might turn into a mist. As a result, it would be difficult
for the oil to return to the oil reservoir (18) due to its own weight, causing a shortage
of oil in the oil reservoir (18). On the other hand, in the present invention, the
possibility of the engaging portion (43) being soaked in the oil is reduced as mentioned
above, which therefore prevents the compressed fluid from being mixed with the oil,
and also prevents the oil from turning into a mist. Thus, the oil used to lubricate
the sliding portion (44) can immediately return to the oil reservoir (18), and so-called
oil shortage can be prevented.
[0027] According to the first aspect of the invention, the recess is configured as an annular
groove (78). This prevents partial contact between the drive shaft (60) and the bearing
(28). That is, in the present invention, the annular groove (78) functions not only
as a recess (78) for accumulating the oil but also as a so-called elastic groove.
This allows for simplifying the device structure.
[0028] According to the second aspect of the invention, the oil which has flowed out into
the receiving portion (26) returns to the oil reservoir (18) via the oil exhaust channel
(80). This prevents the engaging portion (43) from being soaked in the oil, thereby
reducing the possibility of the oil being agitated by the engaging portion (43). In
particular, according to the third aspect of the invention, the inlet port (80a) of
the oil exhaust channel (80) is level with the bottom (26a) of the receiving portion
(26). Thus, the oil in the receiving portion (26) can be immediately discharged. Further,
according to the fourth aspect of the invention, the inlet port (80a) of the oil exhaust
channel (80) is opened to the inside of the recess (78). This prevents the oil in
the recess (78) from overflowing into the receiving portion (26). As a result, according
to the fourth aspect of the invention, the rise in the oil level of the receiving
portion (26) is effectively prevented, thereby reducing the possibility of the oil
being agitated by the engaging portion (43) with reliability.
[0029] According to the fifth aspect of the invention, the inside of the recess (78) is
partitioned into a first space (S1) and the second space (S2) by a partition member
(100), and the first space (S1) communicating with the oil supply channel (90) has
a larger volume than the second space (S2). This prevents a shortage of the oil to
be supplied from the oil supply channel (90) to the sliding portion (35, 45) of the
compression mechanism (20). As a result, the sliding portion (35, 45) of the compression
mechanism (20) is lubricated successfully, and the reliability of the scroll compressor
is improved eventually.
[0030] According to the sixth aspect of the invention, the inlet port (90a) of the oil supply
channel (90) is located at a lower level than the inlet port (80a) of the oil exhaust
channel (80). This prevents a shortage of the oil to be supplied from the oil supply
channel (90) to the sliding portion (35, 45) of the compression mechanism (20). As
a result, the sliding portion (35, 45) of the compression mechanism (20) is lubricated
as intended, and the reliability of the scroll compressor is improved eventually.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031]
FIG. 1 is a vertical cross-sectional view illustrating the general configuration of
a scroll compressor according to an embodiment.
FIG. 2 is a vertical cross-sectional view illustrating, on a larger scale, main parts
of a compression mechanism and housing according to an embodiment.
FIG. 3 is a horizontal cross-sectional view illustrating the internal structure of
the compression mechanism.
FIG. 4 is a cross-sectional view taken along the plane X-X of FIG. 2.
FIG. 5 illustrates a scroll compressor of a first variation and corresponds to FIG.
2.
FIG. 6 is a perspective view illustrating an internal structure of a central recess
in a scroll compressor of a second variation.
FIG. 7 is a horizontal cross-sectional view illustrating the internal structure of
the central recess in the scroll compressor of the second variation.
DESCRIPTION OF EMBODIMENTS
[0032] An embodiment of the present invention will now be described in detail with reference
to the drawings. The following embodiment is an only preferred example in nature,
and is not intended to limit the scope, applications, and use of the invention.
[0033] An embodiment of the present invention will be described. A scroll compressor (10)
of the present embodiment is a hermetically sealed compressor. The scroll compressor
(10) is connected to a refrigerant circuit, which performs a refrigeration cycle,
to suck and compress a refrigerant in the refrigerant circuit.
<General Configuration for Scroll Compressor>
[0034] As illustrated in FIG. 1, the scroll compressor (10) has a casing (15) which houses,
in its inner space, a compression mechanism (20), an electric motor (50), a lower
bearing member (55), and a drive shaft (60). The casing (15) is a vertically elongated
cylindrical hermetic container. The compression mechanism (20), the electric motor
(50), and the lower bearing member (55) are arranged in this order from top to bottom
in the inner space of the casing (15). The drive shaft (60) is arranged such that
its axial direction is parallel to the height direction of the casing (15). The structure
of the compression mechanism (20) will be described later in detail.
[0035] A suction pipe (16) and a discharge pipe (17) are attached to the casing (15). Both
of the suction pipe (16) and the discharge pipe (17) pass through the casing (15).
The suction pipe (16) is connected to the compression mechanism (20). The discharge
pipe (17) is opened to the inner space of the casing (15) between the electric motor
(50) and the compression mechanism (20).
[0036] The lower bearing member (55) has a central cylindrical portion (56) and an arm portion
(57). Although FIG. 1 illustrates only one arm portion (57), the lower bearing member
(55) actually has three arm portions (57). The central cylindrical portion (56) has
an approximately cylindrical shape. Each of the arm portions (57) extends outward
from the outer peripheral surface of the central cylindrical portion (56). The three
arm portions (57) of the lower bearing member (55) are spaced apart from each other
at substantially equal angles. Projecting ends of the respective arm portions (57)
are fixed to the casing (15). A bearing metal (58) is inserted in the vicinity of
an upper end portion of the central cylindrical portion (56). An auxiliary journal
(67) of the drive shaft (60) to be described later is inserted in, and passes through,
this bearing metal (58). The central cylindrical portion (56) functions as a journal
bearing which supports the auxiliary journal (67).
[0037] The electric motor (50) has a stator (51) and a rotor (52). The stator (51) is fixed
to the casing (15). The rotor (52) is arranged coaxially with the stator (51). A main
shaft portion (61) of the drive shaft (60) to be described later is inserted in, and
passes through, this rotor (52). A plurality of core cuts (51a) extending between
both ends of the stator (51) in its axial direction are formed in the outer peripheral
surface of the stator (51) in order to allow a refrigerant and oil to flow therethrough.
[0038] The drive shaft (60) includes the main shaft portion (61), a balance weight portion
(62), and an eccentric portion (63). The balance weight portion (62) is disposed at
a halfway point in the axial direction of the main shaft portion (61). A portion of
the main shaft portion (61) under the balance weight portion (62) passes through the
rotor (52) of the electric motor (50). Another portion of the main shaft portion (61)
over the balance weight portion (62) functions as a main journal (64), and still another
portion of the main shaft portion (61) under the portion passing through the rotor
(52) functions as the auxiliary journal (67). The main journal (64) is inserted in,
and passes through, a bearing metal (28) provided inside a central expansion (27)
of a housing (25). The auxiliary journal (67) is inserted in, and passes through,
the bearing metal (58) provided inside the central cylindrical portion (56) of the
lower bearing member (55).
[0039] The eccentric portion (63) is arranged at the upper end of the drive shaft (60).
The eccentric portion (63) has a columnar shape with a smaller diameter than the main
journal (64), and projects from the upper end surface of the main journal (64). The
axial center of the eccentric portion (63) is parallel to the axial center of the
main journal (64) (i.e., the axial center of the main shaft portion (61)), and is
eccentric with the axial center of the main journal (64). The eccentric portion (63)
in inserted in a bearing metal (44) provided inside a cylindrical portion (43) of
the movable scroll (40). The cylindrical portion (43) of the movable scroll (40) functions
as an engaging portion with which the eccentric portion (63) rotatably engages.
[0040] The drive shaft (60) is provided with an oil supply passage (70). The oil supply
passage (70) has one main passage (74) and three branch passages (71-73). The main
passage (74) extends along the axial center of the drive shaft (60). One end of the
main passage (74) is opened to the bottom end of the main shaft portion (61), and
the other end thereof is opened to the upper end surface of the eccentric portion
(63). A first branch passage (71) is provided for the eccentric portion (63). The
first branch passage (71) extends outward from the main passage (74) in the radial
direction of the eccentric portion (63), and is opened to the outer peripheral surface
of the eccentric portion (63). A second branch passage (72) is provided for the main
journal (64). The second branch passage (72) extends outward from the main passage
(74) in the radial direction of the main journal (64), and is opened to the outer
peripheral surface of the main journal (64). A third branch passage (73) is provided
for the auxiliary journal (67). The third branch passage (73) extends outward from
the main passage (74) in the radial direction of the auxiliary journal (67), and is
opened to the outer peripheral surface of the auxiliary journal (67).
[0041] An oil supply pump (75), which functions as an oil transfer mechanism, is attached
to the lower end of the drive shaft (60). The oil supply pump (75) is a trochoid pump
driven by the drive shaft (60). The oil supply pump (75) is arranged near the starting
end of the main passage (74) of the oil supply passage (70). Further, the oil supply
pump (75) is provided with an inlet port (76), opened downward at its lower end, for
sucking up the refrigeration oil, which is a lubricating oil. The oil supply pump
(75) does not have to be the trochoid pump but may also be any positive displacement
pump driven by the drive shaft (60). Thus, the oil supply pump (75) may be a gear
pump, for example.
[0042] The refrigeration oil, which is a lubricating oil, is accumulated at the bottom of
the casing (15). That is, an oil reservoir (18) is provided at the bottom of the casing
(15). As the drive shaft (60) rotates, the oil supply pump (75) sucks up the refrigeration
oil from the oil reservoir (18) and discharges that refrigeration oil, which then
flows through the main passage (74). The refrigeration oil flowing through the main
passage (74) is supplied to the lower bearing member (55) and the sliding portion
between the compression mechanism (20) and the drive shaft (60). Since the oil supply
pump (75) is a positive displacement pump, the flow rate of the refrigeration oil
in the main passage (74) is proportional to the rotational speed of the drive shaft
(60).
[0043] As also illustrated in FIG. 2, in the casing (15), a housing (25) is provided above
the electric motor (50). The housing (25) has a thick disk-like shape, with its outer
peripheral edge fixed to the casing (15). The housing (25) is provided, at its central
portion, with a central recess (26) and an annular projection (29). The central recess
(26) is a columnar depression opened on the upper surface of the housing (25). The
central recess (26) functions as a receiving portion which receives the cylindrical
portion (43) of the movable scroll (40) and the eccentric portion (63) of the drive
shaft (60). The annular projection (29) surrounds the outer periphery of the central
recess (26), and projects from the upper surface of the housing (25). The projecting
end surface of the annular projection (29) is a flat surface. The projecting end surface
of the annular projection (29) is provided with a ring-like recessed groove along
its circumferential direction. A seal member (29a) is fitted in this recessed groove.
[0044] The housing (25) has the central expansion (27). The central expansion (27) is located
under the central recess (26) and expands downward. The central expansion (27) has
a through hole which vertically runs through the central expansion (27), and into
which the bearing metal (28) is inserted. The main journal (64) of the drive shaft
(60) is inserted in, and passes through, the bearing metal (28) of the central expansion
(27). The central expansion (27) serves as a journal bearing which supports the main
journal (64).
<Configuration for Compression Mechanism>
[0045] As also illustrated in FIG. 2, the compression mechanism (20) includes the fixed
scroll (30) and the movable scroll (40). The compression mechanism (20) is further
provided with an Oldham coupling (24) for regulating the rotational movement of the
movable scroll (40).
[0046] The fixed scroll (30) and the movable scroll (40) are mounted on the housing (25).
The fixed scroll (30) is fixed to the housing (25) with, e.g., a bolt. On the other
hand, the movable scroll (40) engages with the housing (25) via the Oldham coupling
(24), and is relatively movable with respect to the housing (25). The movable scroll
(40) engages with the drive shaft (60) and rotates eccentrically.
[0047] The movable scroll (40) is a member comprised of a movable end plate (41), a movable
lap (42), and the cylindrical portion (43) which are formed integrally with each other.
The movable end plate (41) has a disk shape. The movable lap (42) has a spiral wall
shape, and protrudes from the front surface (the upper surface in FIGS. 1 and 2) of
the movable end plate (41). The cylindrical portion (43) has a cylindrical shape,
and protrudes from the back surface (the lower surface in FIGS. 1 and 2) of the movable
end plate (41).
[0048] The back surface of the movable end plate (41) of the movable scroll (40) is in sliding
contact with the seal member (29a) provided on the annular projection (29) of the
housing (25). On the other hand, the cylindrical portion (43) of the movable scroll
(40) is inserted in the central recess (26) of the housing (25) from over the recess
(26). The bearing metal (44) is inserted in the cylindrical portion (43), and functions
as a sliding portion with which the eccentric portion (63) comes into sliding contact.
The eccentric portion (63) of the drive shaft (60) to be described later is inserted
in the bearing metal (44) of the cylindrical portion (43) from under the bearing metal
(44). The cylindrical portion (43) functions as a journal bearing which slides against
the eccentric portion (63).
[0049] The fixed scroll (30) is a member comprised of a fixed end plate (31), a fixed lap
(32), and an outer peripheral portion (33) which are formed integrally with each other.
The fixed end plate (31) has a disk shape. The fixed lap (32) has a spiral wall shape,
and protrudes from the front surface (the lower surface in FIGS. 1 and 2) of the fixed
end plate (31). The outer peripheral portion (33) has a thick ring-like shape extending
downward from the fixed end plate (31), and surrounds the fixed lap (32).
[0050] The fixed end plate (31) is provided with a discharge port (22). The discharge port
(22) is a through hole provided around the center of the fixed end plate (31), and
runs through the fixed end plate (31) in the thickness direction. Further, the suction
pipe (16) is inserted in a portion of the fixed end plate (31) around its the outer
periphery.
[0051] The compression mechanism (20) is provided with a discharge gas passage (23). The
starting end of the discharge gas passage (23) communicates with the discharge port
(22). Although not shown, the discharge gas passage (23) extends from the fixed scroll
(30) to the housing (25), and the other end thereof is opened to the lower surface
of the housing (25).
[0052] In the compression mechanism (20), the fixed scroll (30) and the movable scroll (40)
are arranged such that the front surface of the fixed end plate (31) and the front
surface of the movable end plate (41) face each other, and that the fixed lap (32)
and the movable lap (42) engage with each other. Such engagement between the fixed
lap (32) and the movable lap (42) forms a plurality of compression chambers (21) in
the compression mechanism (20).
[0053] Further, in the compression mechanism (20), the movable end plate (41) of the movable
scroll (40) and the outer peripheral portion (33) of the fixed scroll (30) are in
sliding contact with each other. More particularly, a portion of the front surface
(the upper surface in FIGS. 1 and 2) of the movable end plate (41) outside the movable
lap (42) is a sliding portion (45) of a movable thrust surface which comes into sliding
contact with the fixed scroll (30). On the other hand, the projecting end surface
(the lower surface in FIGS. 1 and 2) of the outer peripheral portion (33) of the fixed
scroll (30) comes into sliding contact with the sliding portion (45) of the movable
thrust surface of the movable scroll (40). A portion of the projecting end surface
of the outer peripheral portion (33) which is in sliding contact with the sliding
portion (45) of the movable thrust surface is a sliding portion (35) of a fixed thrust
surface. That is, the sliding portion (35) of the fixed thrust surface and the sliding
portion (45) of the movable thrust surface form a sliding portion of the compression
mechanism (20).
[0054] As illustrated in FIGS. 2 and 4, the bottom (26a) of the above-described central
recess (26) is provided with an annular groove (78). The annular groove (78) is configured
as a recess opened upward. The center of the annular groove (78) substantially coincides
with the axial center of the main journal (64), and the annular groove (78) surrounds
entirely the bearing metal (28), which is a bearing. The annular groove (78) may be
implemented as a so-called "elastic groove". That is, the housing (25) is provided
with a cylindrical projection (79) projecting upward between the annular groove (78)
and the bearing metal (28). When the main journal (64) warps radially outward during
rotation of the drive shaft (60), the cylindrical projection (79) elastically deforms
along the main journal (64). This prevents the main journal (64) from making line
contact with the bearing metal (28), i.e., so-called partial contact, thereby reducing
bearing load on the bearing metal (28).
[0055] The oil used to lubricate the bearing metal (28) of the main journal (64) flows through
the oil supply passage (70) into the central recess (26) of the housing (25). The
housing (25) is provided with an oil exhaust channel (80) for delivering the oil which
has flowed out into the central recess (26) to the oil reservoir (18), and an oil
supply channel (90) for delivering this oil to the sliding portion (that is, the sliding
portion (35) of the fixed thrust surface and the sliding portion (45) of the movable
thrust surface) of the compression mechanism (20).
[0056] The oil exhaust channel (80) of the present embodiment is provided for the annular
projection (29) of the housing (25). The oil exhaust channel (80) is comprised of
a horizontal hole (81) which runs radially through a lower end portion of the annular
projection (29), and a vertical hole (82) which extends downward from the outflow
end of the horizontal hole (81). An inlet port (80a) of the oil exhaust channel (80)
is opened to the inside of the central recess (26). The lower portion of the inlet
port (80a) of the oil exhaust channel (80) is substantially level with the bottom
(26a) of the central recess (26). That is, the inlet port (80a) of the oil exhaust
channel (80) is continuous with the bottom (26a) of the central recess (26).
[0057] An oil catch plate (83) is arranged under the vertical hole (82) of the oil exhaust
channel (80). The oil catch plate (83) has an increased-width portion (83a), of which
the width increases upward, and a lower nozzle portion (83b) extending downward from
the increased-width portion (83a). The outflow end (i.e., the lower end) of the lower
nozzle portion (83b) is located in a core cut (51a) of the stator (51).
[0058] The oil supply channel (90) extends from the central expansion (27) to the annular
projection (29) of the housing (25). The oil supply channel (90) is comprised of a
first oil supply hole (91) and a second oil supply hole (92). The first oil supply
hole (91) is formed in the housing (25), and extends radially outward, and obliquely
upward, from the annular groove (78). An inlet port (91a) of the first oil supply
hole (91) is opened to the inside of the annular groove (78). The inlet port (91a)
of the first oil supply hole (91) is located at a lower level than the inlet port
(80a) of the oil exhaust channel (80). Further, the inlet port (91a) of the first
oil supply hole (91) is located at a higher level than the bottom of the annular groove
(78). This structure prevents waste or any other foreign substances collected at the
bottom of the annular groove (78) from entering the oil supply channel (90) through
the inlet port (91a), and eventually prevents the oil supply channel (90) from being
clogged with such waste or any other substances.
[0059] The second oil supply hole (92) runs through the annular projection (29) of the housing
(25) in the axial direction so as to communicate with the outflow end of the first
oil supply hole (91). A screw member (93) is inserted in, and passes through, the
second oil supply hole (92). The head (93a) of the screw member (93) closes the lower
end of the second oil supply hole (92). The screw member (93) narrows the flow path
of the oil in the second oil supply hole (92). That is, the screw member (93) functions
as a pressure-reducing mechanism (a throttle mechanism) that reduces the pressure
of the oil flowing through the second oil supply hole (92).
[0060] As illustrated in FIGS. 2 and 3, the outer peripheral portion (33) of the fixed scroll
(30) is provided with an oil communication passage (94) which communicates with the
second oil supply hole (92), and an oil groove (95) which communicates with the oil
communication passage (94). The inflow end of the oil communication passage (94) is
connected to the second oil supply hole (92) inside the housing (25). The outflow
end of the oil communication passage (94) is opened to the sliding portion (45) of
the movable thrust surface of the movable scroll (40). The oil groove (95) is a recessed
groove provided on the sliding portion (35) of the fixed thrust surface of the outer
peripheral portion (33), and has a ring-like shape surrounding the fixed lap (32).
The oil groove (95) communicates with the outflow end of the oil communication passage
(94).
-Operation-
[0061] Operation of the scroll compressor (10) will be described.
<Operation of Compressing Refrigerant>
[0062] In the scroll compressor (10), the energization of the electric motor (50) causes
the drive shaft (60) to rotate the movable scroll (40). Since the Oldham coupling
(24) regulates the rotational movement of the movable scroll (40), the movable scroll
(40) does not rotate on its own axis but only revolves around.
[0063] When the movable scroll (40) revolves around, a low-pressure gas refrigerant which
has flowed into the compression mechanism (20) through the suction pipe (16) is sucked
into the compression chamber (21) from around outer peripheral edges of the fixed
lap (32) and the movable lap (42). Further revolution of the movable scroll (40) disconnects
the compression chamber (21) from the suction pipe (16), thereby closing the compression
chamber (21). The compression chamber (21) then moves along the fixed lap (32) and
the movable lap (42) toward their inner peripheral edges. In the course of this movement,
the volume of the compression chamber (21) gradually decreases, thus compressing the
gas refrigerant in the compression chamber (21).
[0064] As the volume of the compression chamber (21) gradually decreases with the movement
of the movable scroll (40), the compression chamber (21) comes to communicate with
the discharge port (22) in the end. The refrigerant compressed in the compression
chamber (21) (that is, a high-pressure gas refrigerant) flows into the discharge gas
passage (23) through the discharge port (22), and is then discharged into the inner
space of the casing (15). In the inner space of the casing (15), the high-pressure
gas refrigerant discharged from the compression mechanism (20) is once guided to below
the stator (51) of the electric motor (50), and then flows upward through a gap between
the rotor (52) and the stator (51) and other regions. Thereafter, the high-pressure
gas refrigerant flows out of the casing (15) through the discharge pipe (17).
[0065] The high-pressure gas refrigerant discharged from the compression mechanism (20)
circulates through the inner space of the casing (15) under the housing (25), where
the pressure is substantially equal to the pressure of the high-pressure gas refrigerant.
This means that the pressure of the refrigeration oil accumulated in the oil reservoir
(18) in the casing (15), too, is substantially equal to that of the high-pressure
gas refrigerant.
[0066] On the other hand, although not shown, the inner space of the casing (15) over the
housing (25) communicates with the suction pipe (16), and has almost as much pressure
as the low-pressure gas refrigerant to be sucked into the compression mechanism (20).
This means that in the compression mechanism (20), a space around the outer periphery
of the movable end plate (41) of the movable scroll (40), too, has almost as much
pressure as the low-pressure gas refrigerant.
<Oil Supply Operation at Sliding Portion>
[0067] During the operation of the scroll compressor (10), the rotating drive shaft (60)
drives the oil supply pump (75), thereby sucking up the refrigeration oil accumulated
at the bottom of the casing (15) to the main passage (74) of the oil supply passage
(70). Part of the refrigeration oil flowing through the main passage (74) flows into
the branch passages (71-73), and the rest flows out of the main passage (74) through
its upper end. The oil (the refrigeration oil) which has flowed into the third branch
passage (73) is supplied to a gap between the auxiliary journal (67) and the bearing
metal (58), and is used to lubricate and cool the auxiliary journal (67) and the bearing
metal (58). The oil which has flowed into the second branch passage (72) is supplied
to a gap between the main journal (64) and the bearing metal (28), and is used to
lubricate and cool the main journal (64) and the bearing metal (28).
[0068] The oil which has flowed into the first branch passage (71) is supplied to a gap
between the eccentric portion (63) and the bearing metal (44), and is used to lubricate
and cool the eccentric portion (63) and the bearing metal (44). The oil used to lubricate
the bearing metal (44) flows out into the central recess (26).
[0069] If this oil used to lubricate the bearing metal (44) is accumulated in the central
recess (26), the cylindrical portion (43) of the movable scroll (40) may be soaked
in the oil. If the cylindrical portion (43) performs the eccentric rotational movement
a number of times in such a state, the oil in the central recess (26) constitutes
a resistance to the cylindrical portion (43), and so-called oil churning loss increases.
This leads to an increase in motive energy of the electric motor (50). Further, if
the oil in the central recess (26) is agitated by the cylindrical portion (43), the
high-pressure gas refrigerant in the casing (15) may be mixed with the oil, or the
oil may turn into a fine mist. As a result, after all, it becomes difficult for the
oil agitated in the central recess (26) to go back to the oil reservoir (18) due to
its own weight. This causes a shortage of oil in the oil reservoir (18). The present
embodiment therefore provides the annular groove (78) on the bottom (26a) of the central
recess (26) to prevent the oil in the central recess (26) from being agitated by the
cylindrical portion (43).
[0070] More particularly, the refrigerant which has been used to lubricate the bearing metal
(44) and flowed into the central recess (26) falls down into the annular groove (78)
from the bottom (26a) of the central recess (26). When the oil level in the annular
groove (78) exceeds the level of the inlet port (90a) of the first oil supply hole
(91), the oil in the annular groove (78) flows into the first oil supply hole (91).
This oil passes through the first oil supply hole (91), and then flows upward through
the second oil supply hole (92). In the course of this flow, the high-pressure oil
is decompressed in the second oil supply hole (92) by the screw member (93). The oil
which has passed through the second oil supply hole (92) flows into the oil groove
(95) via the oil communication passage (94) inside the fixed scroll (30). As a result,
the sliding portion of the compression mechanism (20) between the sliding portion
(35) of the fixed thrust surface and the sliding portion (45) of the movable thrust
surface is lubricated with the oil.
[0071] As described above, the oil which has flowed out into the central recess (26) is
appropriately supplied to the sliding portion of the compression mechanism (20) through
the annular groove (78) and the oil supply channel (90). As a result, the rise in
the oil level in the central recess (26) is prevented, thereby reducing the area of
the cylindrical portion (43) of the movable scroll (40) to be soaked in the oil.
[0072] Further, if the oil level in the annular groove (78) rises so much as to make the
oil overflow from the annular groove (78) into the central recess (26), this oil flows
into the oil exhaust channel (80). In the oil exhaust channel (80), the oil sequentially
flows through the horizontal hole (81), the vertical hole (82), and the oil catch
plate (83) to be guided into the core cut (51a). The oil in the core cut (51a) further
flows down along the inner peripheral surface of the casing (15), and is delivered
to the oil reservoir (18) in the end.
[0073] In this manner, the oil which has overflowed from the annular groove (78) returns
directly to the oil reservoir (18) through the oil exhaust channel (80). Thus, the
rise in the oil level in the central recess (26) is prevented, thereby reducing the
area of the cylindrical portion (43) of the movable scroll (40) to be soaked in the
oil.
-Advantages of Embodiment-
[0074] In the embodiment described above, the annular groove (78) is provided on the bottom
(26a) of the central recess (26) of the housing (25), which allows the annular groove
(78) to catch the oil used to lubricate the bearing metal (44). This reduces the possibility
of the cylindrical portion (43) of the movable scroll (40) being soaked in the oil
in the central recess (26), thereby reducing the oil churning loss at the cylindrical
portion (43) during its rotation. As a result, the motive energy of the electric motor
(50) is reduced, which contributes to energy saving more effectively.
[0075] In addition, since this structure prevents the cylindrical portion (43) from agitating
the oil in this manner, it also prevents a compressed fluid from being mixed with
the oil, and further prevents the oil from turning into a mist. Thus, the oil used
to lubricate the bearing metal (44) can immediately return to the oil reservoir (18),
and therefore so-called oil shortage is eliminated.
[0076] Furthermore, in the embodiment described above, the annular groove (78) is provided
around the bearing metal (28) of the main journal (64), which allows for providing
the cylindrical projection (79) between the annular groove (78) and the bearing metal
(28). This structure allows the cylindrical projection (79) to be elastically deformed
along the main journal (64) even if the main journal (64) inclines with respect to
the axial center. Thus, the main journal (64) is prevented from partially contacting
with the bearing metal (28), thereby reducing bearing load on the main journal (64).
The annular groove (78) functions not only as a groove which catches and delivers
the oil to the oil supply channel (90) but also as a so-called elastic groove. This
allows for simplifying the structure of the housing (25).
[0077] On top of that, according to the embodiment described above, part of the oil which
has flowed out into the central recess (26) returns directly to the oil reservoir
(18) through the oil exhaust channel (80). This prevents the cylindrical portion (43)
from being soaked in the oil. In particular, according to the present embodiment,
the inlet port (80a) of the oil exhaust channel (80) is arranged to be level with
the bottom (26a) of the central recess (26). Thus, even when the oil overflows from
the annular groove (78), this oil can be immediately introduced to the oil exhaust
channel (80).
[0078] Furthermore, according to the embodiment described above, the inlet port (90a) of
the oil supply channel (90) is opened to the inside of the annular groove (78), and
the inlet port (80a) of the oil exhaust channel (80) is opened to the inside of the
central recess (26). That is, the inlet port (90a) of the oil supply channel (90)
is located at a lower level than the inlet port (80a) of the oil exhaust channel (80).
Thus, the oil which has flowed out into the central recess (26) is introduced to the
oil supply channel (90) earlier than to the oil exhaust channel (80). This allows
for supplying the oil to the sliding portions (35, 45) of the compression mechanism
(20) successfully, and increases reliability of the scroll compressor (10).
<First Variation of Embodiment>
[0079] The scroll compressor (10) according to a first variation illustrated in FIG. 5 is
different from the above embodiment in the configuration of the oil exhaust channel
(80). Specifically, the inlet port (80a) of the oil exhaust channel (80) of the first
variation is opened to the inside of the annular groove (78). More particularly, the
oil exhaust channel (80) has a horizontal hole (81) which extends radially outward
from inside the annular groove (78), and a vertical hole (82) which extends downward
from the radially outer end of the horizontal hole (81). In the annular groove (78),
the inlet port (90a) of the oil supply channel (90) is located at a lower level than
the inlet port (80a) of the oil exhaust channel (80).
[0080] In the first variation, the oil is introduced to the oil supply channel (90) preferentially
if the oil level in the annular groove (78) is located at a level between the inlet
port (90a) of the oil supply channel (90) and the inlet port (80a) of the oil exhaust
channel (80). However, when the oil level in the annular groove (78) reaches the level
of the inlet port (80a) of the oil exhaust channel (80), the oil is introduced to
both of the oil supply channel (90) and the oil exhaust channel (80). Thus, in the
first variation, too, the oil which has flowed out into the central recess (26) is
introduced to the oil supply channel (90) earlier than to the oil exhaust channel
(80). This allows the oil to be supplied to the sliding portions (35, 45) of the compression
mechanism (20) successfully, and increases the reliability of the scroll compressor
(10).
[0081] Further, in the first variation, the oil in the annular groove (78) is prevented
from overflowing into the central recess (26), since the oil in the annular groove
(78) is delivered to both of the oil supply channel (90) and the oil exhaust channel
(80). As a result, the cylindrical portion (43) of the movable scroll (40) is more
reliably prevented from being soaked in the oil.
[0082] The other functions and effects of the first variation are the same as those of the
embodiment described above.
<Second Variation of Embodiment>
[0083] The second variation illustrated in FIGS. 6 and 7 includes a housing (25) which has
a similar configuration to the counterpart of the first variation but which includes
a partition member (100) in the annular groove (78). The partition member (100) extends
from a lower bottom of the annular groove (78) to an upper open end of the annular
groove (78) in the axial direction of the annular groove (78). The partition member
(100) has an approximately U-shaped cross-section on a plane perpendicular to the
axial direction of the annular groove (78), and is fitted in the annular groove (78).
[0084] The partition member (100) has an arc-shaped vertical wall (100a) which is curved
along the inner peripheral surface of the annular groove (78), and a pair of sidewalls
(100b) which are located at both ends of the vertical wall (100a) in its circumferential
direction. The vertical wall (100a) is arranged to face the inlet port (80a) of the
oil exhaust channel (80). Each of the sidewalls (100b) extends in a radial direction
from the inner peripheral surface to the outer peripheral surface of the annular groove
(78). This partition member (100) partitions the inside of the annular groove (78)
into a first space (S1) outside the partition member (100), and a second space inside
the partition member (100). The inlet port (90a) of the oil supply channel (90) communicates
with the first space (S1). The inlet port (80a) of the oil exhaust channel (80) communicates
with the second space (S2).
[0085] In the second variation, the opening area of the upper end of the first space (S1)
is larger than the opening area of the upper end of the second space (S2). That is,
the volume of the first space (S1) is larger than the volume of the second space (S2)
inside the annular groove (78). Thus, in the second variation, the oil which has flowed
out into the central recess (26) flows down more into the first space (S1) than into
the second space (S2), thus making it possible to store a sufficient amount of oil
in the first space (S1). This allows the oil to be supplied to the sliding portions
(35, 45) of the compression mechanism (20) via the first space (S1) and the oil supply
channel (90) successfully, and increases the reliability of the scroll compressor
(10).
[0086] The other functions and effects of the second variation are the same as those of
the above embodiment.
INDUSTRIAL APPLICABILITY
[0087] As can be seen from the foregoing description, the present invention relates to a
scroll compressor, and is particularly useful for providing an effective measure to
supply oil to a sliding portion of a compression mechanism.
DESCRIPTION OF REFERENCE CHARACTERS
[0088]
- 10
- scroll compressor
- 15
- casing
- 18
- oil reservoir
- 20
- compression mechanism
- 25
- housing
- 26
- central recess (receiving portion)
- 26a
- bottom
- 28
- bearing metal (bearing)
- 30
- fixed scroll
- 35
- sliding portion of fixed thrust surface
- 40
- movable scroll
- 43
- cylindrical portion (engaging portion)
- 44
- bearing metal (sliding portion)
- 45
- sliding portion of movable thrust surface
- 50
- electric motor
- 60
- drive shaft
- 70
- oil supply passage
- 75
- oil supply pump (oil transfer mechanism)
- 78
- annular groove (recess)
- 80
- oil exhaust channel
- 80a
- inlet port (on the oil exhaust channel side)
- 90
- oil supply channel
- 90a
- inlet port (on the oil supply channel side)
- 100
- partition member
- S1
- first space
- S2
- second space