TECHNICAL FIELD
[0001] The present invention relates to an oil pump which sucks and discharges oil (lubricant
oil) of an internal combustion engine (an engine) or the like, and in particular,
relates to a trochoid type oil pump including an inner rotor and an outer rotor.
BACKGROUND ART
[0002] There has been known a trochoid type oil pump including a housing which has an inlet
port for sucking oil, a discharge port for discharging oil, a purge port (an air vent
port, a bubble ejection port, or a deairing port) for ejecting air mixed with oil,
and the like, an outer rotor which has internal teeth as being rotatably arranged
in the housing, an inner rotor which has external teeth engaged with the internal
teeth of the outer rotor and which defines a volume-varying pump chamber in cooperation
with the outer rotor, a rotary shaft which is rotatably supported by the housing to
rotate the inner rotor, and the like. Here, pumping action is obtained by rotating
the inner rotor via the rotary shaft and rotating the outer rotor as being coordinated
with the rotation of the inner rotor, so that oil sucked through the inlet port is
pressurized and discharged through the discharge port while air (bubble) and the like
mixed with oil is ejected through the purge port (for example, see Patent Literature
1, Patent Literature 2, Patent Literature 3, and the like).
[0003] By the way, in the abovementioned oil pump, the purge port (an air vent port, a bubble
ejection port, or a deairing port) is arranged at a portion corresponding to a pressurizing
chamber (compression process) at a side close to the discharge port. Accordingly,
in a normal revolution range of an engine, oil is not sucked conversely through the
purge port while air-mixed oil may be ejected therethrough.
[0004] Here, during development of an oil pump having characteristics to work in a wide
engine revolution range, the inventor has acknowledged occurrence of a case that the
pump chamber communicates with the purge port as well concurrently with the inlet
port depending on settings such as a ratio between an oil discharge rate and a purge
ejection rate (an ejection rate of air-mixed oil through the purge port) and rotor
size difference, causing a phenomenon of sucking oil through the purge port at engine
starting or sucking oil through the purge port due to following delay of an intake
process at high engine revolution range.
Cited Literature
Patent Literature
[0005]
Patent Literature 1: Japanese Patent Application Laid-Open No. 9-203308
Patent Literature 2: Japanese Patent Application Laid-Open No. 6-167278
Patent Literature 2: Japanese Utility-model Application No. 2-107738 (Japanese Utility-model Application Laid-open No. 4-65974) (Microfilm)
SUMMARY OF THE INVENTION
[0006] To address the above issues, an object of the present invention is to provide an
oil pump capable of ensuring desired pump performance while preventing sticking and
the like due to entering of foreign matter and the like even when oil is sucked through
a purge port, and capable of achieving improvement of pump performance, improvement
of durability, and the like in a wide engine revolution range from a low revolution
range to a high revolution range including a revolution range having less air mixing,
a revolution range having less emphasis on air mixing, and the like.
[0007] An oil pump according to the present invention includes a housing which includes
an inlet port to suck oil, a discharge port to discharge oil, and a purge port to
eject air-mixed oil with air mixed; an inner rotor which is arranged in the housing
as being rotatable about a predetermined axis line; an outer rotor which is arranged
in the housing to be rotated as being interlocked with the inner rotor; and a filter
member which is arranged at the housing from the outside thereof to prevent foreign
matter from entering through the purge port.
[0008] According to the configuration, for example, in a case that the oil pump is mounted
on an engine (in an oil pan thereof), under normal operational conditions, oil (lubricant
oil) is sucked into the pump chamber due to pumping action of the inner rotor and
the outer rotor, and then, the sucked air-mixed oil is pressurized. Subsequently,
a part of the air-mixed oil is ejected to the outside of the housing (into the oil
pan) through the purge port, and then, remaining oil is discharged through the discharge
port and pressure-fed toward various lubrication areas.
[0009] On the other hand, owing to a high oil level in the oil pan at engine starting or
following delay of an intake process at high speed revolution, there may be a case
that oil is sucked through the purge port. In this case, since oil is sucked into
the pump chamber through the filter member, sticking and the like due to entering
of foreign matter and the like can be prevented and desired pump performance can be
ensured accordingly. Further, improvement of pump performance, improvement of durability,
and the like can be achieved in a wide engine revolution range.
[0010] In the above configuration, it is possible to adopt a configuration that the purge
port is arranged at a range capable of providing communication, concurrently with
the inlet port, with a pump chamber defined by the inner rotor and the outer rotor.
[0011] According to the configuration, when oil is sucked into the pump chamber P through
the inlet port, oil is sucked through the purge port as well depending on revolution
speed. Accordingly, even in a revolution range having less contained amount of air
or a revolution range having less emphasis on air discharging, the oil pump can be
used as a pump to suck and discharge oil.
[0012] In the above configuration, it is possible to adopt a configuration that the housing
includes a housing body including a concave portion for containing the inner rotor
and the outer rotor and a housing cover which is connected to the housing body to
close an opening of the housing body, the purge port is formed at the housing cover,
and the filter member is attached to the housing cover from the outside.
[0013] According to the configuration, attaching and detaching of the filter member can
be easily performed from the outside of the housing. Therefore, replacement operation
and the like of the filter member can be easily performed as well without disassembling
the housing.
[0014] In the above configuration, it is possible to adopt a configuration that the inner
rotor and the outer rotor include an upstream rotor including a first inner rotor
and a first outer rotor and a downstream rotor including a second inner rotor and
a second outer rotor, the upstream rotor and the downstream rotor being arranged adjacently
in a direction of the axis line, the housing includes a spacer member which is interposed
between the upstream rotor and the downstream rotor, the inlet port is arranged to
be faced to the upstream rotor, the discharge port is arranged to be faced to the
downstream rotor, the purge port is arranged to be faced to the upstream rotor, and
a communication port which introduces oil discharged from the upstream rotor to the
downstream rotor is arranged at the spacer member.
[0015] According to the configuration, owing to that the two-stage trochoid pump including
the upstream rotor and the downstream rotor is adopted, desired pumping characteristics
can be ensured while achieving downsizing in an outer diameter dimension of the apparatus.
Further, since the inlet port, the purge port, and the discharge port are arranged
as described above, pump efficiency can be improved.
[0016] In the above configuration, it is possible to adopt a configuration that the inlet
port is arranged at the spacer member between the upstream rotor and the downstream
rotor to be faced to the upstream rotor.
[0017] According to the configuration, oil sucked through the inlet port can be reliably
pressurized in the upstream rotor and supplied to the downstream rotor through the
communication port. As a whole, pumping performance can be improved.
[0018] In the above configuration, it is possible to adopt a configuration that the inner
rotor and the outer rotor are formed in four blades and five nodes.
[0019] According to the configuration, with a structure being likely to have arrangement
that the inlet port and the purge port concurrently communicate with the pump chamber,
pump performance and durability can be improved while ensuring a desired discharge
rate.
[0020] In the above configuration, it is possible to adopt a configuration that the purge
port is formed to be opened in an approximate L-shape as being elongated in the radial
direction passing through the axis line and being elongated in a rotation direction
of the inner rotor and the outer rotor at an outer edge thereof in the radial direction.
[0021] According to the configuration, ejection of air through the purge port can be effectively
performed.
[0022] According to an oil pump having the abovementioned structure, even when oil is sucked
through a purge port, sticking and the like due to entering of foreign matter and
the like can be prevented and desired pump performance can be ensured. Further, in
a wide engine revolution range including a revolution range having less air mixing,
a revolution range having less emphasis on air mixing, and the like, improvement of
pump performance, improvement of durability, and the like can be achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023]
FIG. 1 is a front view illustrating an embodiment of an oil pump according to the
present invention.
FIG. 2 is a sectional view illustrating the inside of the oil pump illustrated in
FIG. 1.
FIG. 3 is a front view illustrating a housing body which structures a part of the
oil pump illustrated in FIG. 1.
FIG. 4A is a plane view of a housing cover which structures a part of the oil pump
illustrated in FIG. 1 viewed from the rear R side (inner surface side).
FIG. 4B is a sectional view of the housing cover which structures a part of the oil
pump illustrated in FIG. 1 at E1-E1 in FIG. 4A.
FIG. 5 is an exploded sectional view of the housing cover, a filter member, and a
fixing ring structuring a part of the oil pump illustrated in FIG. 1.
FIG. 6 is a sectional view illustrating a rotor case which structures a part of the
oil pump illustrated in FIG. 1.
FIG. 7A is an end view of the rotor case illustrated in FIG. 6 viewed from the front
F side.
FIG. 7B is an end view of the rotor case illustrated in FIG. 6 viewed from the rear
R side.
FIG. 8A is a plane view of a side plate which structures a part of the oil pump illustrated
in FIG. 1 viewed from the front F side.
FIG. 8B is a sectional view of the side plate which structures a part of the oil pump
illustrated in FIG. 1 at E2-E2 in FIG. 8A.
FIG. 9A is a plane view illustrating an inner rotor and an outer rotor structuring
a part of the oil pump illustrated in FIG. 1 viewing an upstream rotor including a
first inner rotor and a first outer rotor from the rear R side.
FIG. 9B is a plane view illustrating an inner rotor and an outer rotor structuring
a part of the oil pump illustrated in FIG. 1 viewing a downstream rotor including
a second inner rotor and a second outer rotor from the front F side.
FIG. 10 is a plane view viewing from the rear R side as illustrating a relation of
an inlet port and a purge port against a pump chamber defined by the first inner rotor
and the first outer rotor which structure the upstream rotor.
FIG. 11 is an exploded sectional view illustrating another embodiment of a method
for attaching a filter member which structures a part of the oil pump illustrated
in FIG. 1.
EMBODIMENT OF THE INVENTION
[0024] In the following, embodiments of the present invention will be described with reference
to the attached drawings.
[0025] As illustrated in FIGs. 1 and 2, an oil pump according to an embodiment includes
a housing body 10 and a housing cover 20 which constitute a housing, a rotary shaft
30 which is supported by the housing as being rotatable about an axis line S, a rotor
case 40 which is assembled in the housing, a side plate 50 which is in contact with
an end face of the rotor case 40, an O-ring 60 as an urging member which urges the
side plate 50 toward the rotor case 40 in the direction of the axis line S, an upstream
rotor 70, including a first inner rotor 71 and a first outer rotor 72, which is contained
in the rotor case 40, a downstream rotor 80, including a second inner rotor 81 and
a second outer rotor 82, which is contained in the rotor case 40 as being adjacent
to the upstream rotor 70 in the direction of the axis line S, a filter member 90 which
is attached to the housing cover 20, and the like.
[0026] The housing body 10 made of aluminum material for weight saving and the like is configured
to form a concave portion for containing the upstream rotor 70 and the downstream
rotor 80 along with the rotor case 40. As illustrated in FIGs. 2 and 3, the housing
body 10 includes a bearing hole 11 for roratably supporting one end portion 31 of
the rotary shaft 30 via a bearing G, a cylindrical inner circumferential face 12 to
which the rotor case 40 is fitted, two circular end faces 13 which are formed around
the bearing hole 11 as having diameters lessened to form a stepped portion at a back
side of the inner circumferential face 12, an inlet passage 14 through which oil is
sucked as being formed by removing a part of the inner circumferential face 12 and
drilling thereat outward in the radial direction, a discharge passage 15 through which
pressurized oil is discharged as being formed at a bottom side, a positioning hole
16 for positioning the side plate 50, a joint face 17 for joining the housing cover
20, screw holes 18 into which bolts B are screwed for fastening the housing cover
20, positioning holes 19 for positioning the housing cover 20, and the like.
[0027] The housing cover 20 is made of aluminum material being the same as the housing body
10 for weight saving and the like. As illustrated in FIGs. 1, 2, 4A, 4B, and 5, the
housing cover 20 includes a bearing hole 21 for rotatably supporting the other end
portion 32 of the rotary shaft 30 via a bearing G, a concave portion 22 which is faced
to a later-mentioned inlet port 44b in the direction of the axis line S, a concave
portion 23 which is faced to a later-mentioned communication port 44e in the direction
of the axis line S, a purge port 24 through which air mixed with sucked oil (air-mixed
oil) is ejected, circular holes 25 through which the bolts B pass, positioning holes
26 for performing positioning to the housing cover 10, a positioning hole 27 for positioning
the rotor case 40, a counterbore portion 28 to which a filter member 90 and a fixing
ring 91 are fitted, and the like.
[0028] The housing cover 20 is joined to the joint face 17 to close an opening of the housing
body 10 while a positioning pin fitted into the positioning hole 19 is fitted into
the positioning hole 26 and a positioning pin fitted into a positioning hole 45a of
the rotor case 40 is fitted into the positioning hole 27. Then, the housing cover
20 is connected to the housing body 10 by screwing the bolts B into the screw holes
18 as passing through the circular holes 25 from the outer side.
[0029] As illustrated in FIGs. 4A and 9A, the purge port 24 is opened to be approximately
L-shaped as being elongated in the radial direction passing through the axis line
S and being elongated in a rotation direction (an arrow direction) of the first inner
rotor 71 and the first outer rotor 72 at an outer edge thereof in the radial direction.
According to the above, ejection of air through the purge port 24 can be effectively
performed.
[0030] Here, the purge port 24 is not limited to have the abovementioned shape. It is also
possible to adopt an appropriate shape in accordance with a target purge ejection
rate and the like.
[0031] As illustrated in FIG. 2, the rotary shaft 30 made of steel or the like is formed
as being elongated in the direction of the axis line S. The rotary shaft 30 includes
the one end portion 31 which is supported by the bearing hole 11 of the housing body
10 via the bearing G, the other end portion 32 which is supported by the bearing hole
21 of the housing cover 20 via the bearing G, a shaft portion 33 which integrally
rotates the first inner rotor 71 of the upstream rotor 70, a shaft portion 34 which
integrally rotates the second inner rotor 81 of the downstream rotor 80, a shaft portion
35 which is supported by the bearing G, and the like.
[0032] The rotary shaft 30 is configured to be rotationally driven as being connected to
a rotary member or the like which structures a part of an engine.
[0033] The rotor case 40 is made of steel, casting iron, sintered steel, or the like. As
illustrated in FIGs. 2, 6, 7A, and 7B, the rotor case 40 includes a cylindrical portion
41 which is centered at the axis line S, an inner circumferential face 42 centered
at an axis line L1 which is shifted by a predetermined amount from the axis line S
at the inner side of the cylindrical portion 41, an inner circumferential face 43
centered at an axis line L2 which is shifted by a predetermined amount from the axis
line S at the inner side of the cylindrical portion 41, a middle wall portion 44 as
a spacer member formed between the inner circumferential face 42 and the inner circumferential
face 43 in the direction of the axis line S, a bearing hole 44a arranged at the middle
wall portion 44, an inlet port 44b which is arranged at the middle wall portion 44,
an upstream rotor discharge port 44c which is arranged at the middle wall portion
44, a downstream rotor inlet port 44d which is arranged at the middle wall portion
44, the communication port 44e through which the upstream rotor discharge port 44c
and the downstream rotor inlet port 44d are mutually connected, an end face 45 with
which the housing cover 20 is in contact, a positioning hole 45a which is formed at
the end face 45, an end face 46 with which the side plate 50 is in contact, a positioning
hole 46a which is formed at the end face 46, and the like.
[0034] The cylindrical portion 41 is formed to have an outer diameter dimension so that
the cylindrical portion 41 is fitted into the housing body 10 as being capable of
relatively moving in the direction of the axis line S in accordance with difference
between thermal deformation (expansion and contraction) amounts of the housing body
10 and the rotor case 40 while being intimately contacted to the inner circumferential
face 12 of the housing body 10.
[0035] The inner circumferential face 42 is formed to have a dimension so that the first
outer rotor 72 of the upstream rotor 70 is in contact with the inner circumferential
face 42 rotatably (slidably) about the axis line L1.
[0036] The inner circumferential face 43 is formed to have a dimension so that the second
outer rotor 82 of the downstream rotor 80 is in contact with the inner circumferential
face 43 rotatably (slidably) about the axis line L2.
[0037] The inlet port 44b is formed so as to be faced to (a pump chamber P of) the upstream
rotor 70 while communicating with the inlet passage 14.
[0038] Thus, the inlet port 44b is arranged between the upstream rotor 70 and the downstream
rotor 80 so as to be faced to the upstream rotor 70. Accordingly, oil sucked through
the inlet port 44b can be reliably pressurized in the upstream rotor 70 and is supplied
to the downstream rotor 80 through the communication port 44e. As a whole, pumping
performance can be improved.
[0039] The communication port 44e is configured to cause communication between the upstream
rotor discharge port 44c and the downstream rotor inlet port 44d so that oil discharged
from the upstream rotor 70 is introduced to the downstream rotor 80.
[0040] The rotor case 40 is assembled (fitted) to the inner circumferential face 12 of the
housing body 10 in a state of containing the upstream rotor 70 at the inner circumferential
face 42 and the downstream rotor 80 at the inner circumferential face 43 along with
the rotary shaft 30 while the positioning pin fitted into the positioning hole 16
is fitted into the positioning hole 46a as sandwiching the O-ring 60 and the side
plate 50 in cooperation with the end face 13.
[0041] The side plate 50 is formed disc-shaped as being made of steel, casted iron, sintered
steel, aluminum alloy, or the like. As illustrated in FIGs. 2 and 8, the side plate
50 includes a circular hole 51 through which the rotary shaft 30 passes, a discharge
port 52 through which oil pressurized by the downstream rotor 80 is discharged, a
positioning hole 53, a concave portion 54 which receives one end side of the bearing
G, and the like.
[0042] The side plate 50 is configured to be assembled to the housing body 10 as sandwiching
the O-ring 60 at a space against the end face 13 while a positioning pin fitted into
the positioning hole 16 of the housing body 10 passes through the positioning hole
53.
[0043] The O-ring 60 is formed circularly as being made of elastically-deformable rubber
material or the like and is arrange between the end face 13 of the housing body 10
and the side plate 50. The O-ring 60 is assembled as being compressed by a predetermined
compression amount in the direction of the axis line S to urge the side plate 50 toward
the end face 46 of the rotor case 40.
[0044] The upstream rotor 70 is made of steel, sintered steel, or the like. As illustrated
in FIG. 9A, the upstream rotor 70 includes the first inner rotor 71 and the first
outer rotor 72.
[0045] The first inner rotor 71 is formed as an external gear which has four crests and
roots (cavities) while including a fitting hole 71a into which the shaft portion 33
of the rotary shaft 30 is fitted.
[0046] The first outer rotor 72 is formed as an internal gear which has five crests (inner
teeth) and roots (cavities) to be engaged with the four crests (external teeth) and
roots (cavities) of the first inner rotor 71 at the inner circumference thereof while
including an outer circumferential face 72a which is slidably fitted to the inner
circumferential face 42 of the rotor case 40.
[0047] That is, the upstream rotor 70 (the first inner rotor 71 and the first outer rotor
72) is a trochoid pump having four blades and five nodes.
[0048] When the first inner rotor 71 is rotated along with the rotary shaft 30 in an arrow
direction about the axis line S (counterclockwise in FIG. 9A), the first outer rotor
72 is coordinated and rotated in an arrow direction about the axis line L1 (counterclockwise
in FIG. 9A). Accordingly, volume of the pump chamber P defined by both thereof is
varied and oil is sucked through the inlet port 44b and pressurized subsequently.
Air-mixed oil is ejected through the purge port 24 in the pressurization process,
and subsequently, remaining oil is discharged through the upstream rotor discharge
port 44c to the downstream rotor 80. Then, the above processes are to be continuously
repeated.
[0049] Further, as illustrated in FIG. 10, , the purge port 24 is arranged at a range to
be capable of communicating, concurrently with the inlet port 44b, with the pump chamber
P which is defined by the first inner rotor 71 and the first outer rotor 72. Accordingly,
in a case that an oil level in an oil pan at engine starting is high or a case that
following delay of an intake process occurs at high speed revolution, there is a possibility
that oil may be sucked into the pump chamber P through the purge port 24.
[0050] That is, when oil is sucked into the pump chamber P through the inlet port 44b, oil
is sucked through the purge port 24 as well depending on revolution speed. Accordingly,
even in a revolution range having less contained amount of air or a revolution range
having less emphasis on air discharging, the oil pump can be used as a pump to suck
and discharge oil.
[0051] The downstream rotor 80 is made of steel, sintered steel, or the like. As illustrated
in FIG. 9B, the downstream rotor 80 includes the second inner rotor 81 and the second
outer rotor 82.
[0052] The second inner rotor 81 is formed as an external gear which has four crests and
roots (cavities) at the outer circumferential face thereof while including a fitting
hole 81a into which the shaft portion 34 of the rotary shaft 30 is fitted.
[0053] The second outer rotor 82 is formed as an internal gear which has five crests (inner
teeth) and roots (cavities) to be engaged with the four crests (external teeth) and
roots (cavities) of the second inner rotor 81 at the inner circumference thereof while
including an outer circumferential face 82a which is slidably fitted to the inner
circumferential face 43 of the rotor case 40.
[0054] That is, the downstream rotor 80 (the second inner rotor 81 and the second outer
rotor 82) is a trochoid pump having four blades and five nodes.
[0055] When the second inner rotor 81 is rotated along with the rotary shaft 30 in an arrow
direction (clockwise in FIG. 9B) about the axis line S, the second outer rotor 82
is coordinated and rotated in an arrow direction (clockwise in FIG. 9B) about the
axis line L2. Accordingly, volume of the pump chamber P defined by both thereof is
varied and oil is sucked through the downstream inlet port 44d and pressurized subsequently.
Then, oil is discharged through the discharge port 52 toward an external lubrication
area. The above processes are to be repeated continuously.
[0056] Owing to that the two-stage trochoid pump including the upstream rotor 70 and the
downstream rotor 80 is adopted as described above, desired pumping characteristics
can be ensured while achieving downsizing in an outer diameter dimension of the apparatus.
Further, since the inlet port 44b, the purge port 24, and the discharge port 52 are
arranged as described above, pump efficiency can be improved.
[0057] Further, the rotor case 40 and the side plate 50 structures a second housing which
contains the upstream rotor 70 and the downstream rotor 80 at the inside of the housing
(the housing body 10 and the housing cover 20).
[0058] The rotor case 40 and the side plate 50 are made of the same material (steel, sintered
steel, or the like) as the upstream rotor 70 and the downstream rotor 80. Here, even
in a case that a gap is to be generated in the direction of the axis line S with thermal
expansion of the housing (the housing body 10 and the housing cover 20) formed of
aluminum, the rotor case 40 and the side plate 50 are urged to one side in the direction
of the axis line S with an urging force of the O-ring 60. Accordingly, desired pump
performance (discharge characteristics) can be ensured by preventing a gap from being
generated at both side faces of the upstream rotor 70 and both side faces of the downstream
rotor 80.
[0059] As illustrated in FIGs. 1 and 5, the filter member 90 is formed to have a hemispherical
shape with a ring-shaped brim portion as being meshed to a predetermined size to eliminate
foreign matter mixed in oil.
[0060] The filter member 90 is fitted to the counterbore portion 28 to cover the purge port
24 of the housing cover 20, and then, a ring-shaped fixing ring 91 is fitted thereto
from the above. Accordingly, the filter member 90 is attached to the housing cover
20 from the outside.
[0061] Thus, attaching and detaching of the filter member 90 can be easily performed from
the outside of the housing (the housing body 10 and the housing cover 20). Therefore,
replacement operation and the like of the filter member 90 can be easily performed
as well without disassembling the housing (the housing body 10 and the housing cover
20).
[0062] Here, not limited to the meshed filter member 90 having a hemispherical shape and
the fixing ring 91 for fixing thereof, it is possible to adopt a filter member whose
structure and shape are different and a fixing way therefor.
[0063] For example, as illustrated in FIG. 11, it is possible to adopt a C-shaped snap ring
91' instead of the fixing ring 91 and to arrange a ring-shaped groove 28' at the inner
circumferential face of the counterbore portion 28 of the housing cover 20.
[0064] According to the above, the filter member 90 is fitted to the counterbore portion
28 to cover the purge port 24 of the housing cover 20, and then, a C-shaped snap ring
91' is fitted into the ring-shaped groove 28'. Thus, the filter member 90 is attached
to the housing cover 20 from the outside.
[0065] Similarly in this case as well, attaching and detaching of the filter member 90 can
be easily performed from the outside of the housing (the housing body 10 and the housing
cover 20). Therefore, replacement operation and the like of the filter member 90 can
be easily performed as well without disassembling the housing (the housing body 10
and the housing cover 20).
[0066] Next, operation of the oil pump will be described with reference to FIGs. 9A, 9B
and 10.
[0067] First, in a state that an engine is in a normal revolution range (in a state that
oil is not sucked through the purge port 24), the upstream rotor 70 (the first inner
rotor 71 and the first outer rotor 72) is rotated counterclockwise in FIG. 9A and
oil is sucked into the pump chamber P of the upstream rotor 70 through the inlet passage
14 and the inlet port 44b.
[0068] Owing to continuous rotation of the upstream rotor 70, the oil sucked into the pump
chamber P is pressurized. In the pressurization process, air-mixed oil is forcedly
ejected outside through the purge port 24. Further, the remaining oil is introduced
to the downstream rotor 80 through the upstream rotor discharge port 44c, the communication
port 44e, and the downstream rotor inlet port 44d.
[0069] Subsequently, the oil is sucked into the pump chamber P of the downstream rotor 80
through the downstream rotor inlet port 44d with clockwise rotation in FIG. 9B of
the downstream rotor 80 (the second inner rotor 81 and the second outer rotor 82).
[0070] Owing to continuous rotation of the downstream rotor 80, the oil sucked into the
pump chamber P is pressurized and supplied to an external lubrication area through
the discharge port 52 and the discharge passage 15.
[0071] Practically, cooperative action of the upstream rotor 70 (the first inner rotor 71
and the first outer rotor 72) and the downstream rotor 80 (the second inner rotor
81 and the second outer rotor 82) causes the respective pump chambers to continuously
perform sucking of oil, pressurizing of oil, ejecting of mixed air (air-mixed oil),
and discharging of oil.
[0072] On the other hand, at engine starting (when an oil level in an oil pan is high) or
at high speed revolution (when following delay of an intake process occurs against
a normal pump process), oil is sucked into the pump chamber P (defined by the first
inner rotor 71 and the first outer rotor 72) of the upstream rotor 70 not only through
the inlet port 44b but also through the purge port 24, as illustrated in FIG. 10.
That is, when oil is sucked into the pump chamber P through the inlet port 44b, oil
is also sucked through the purge port 24. Accordingly, even in a revolution range
having less contained amount of air or a revolution range having less emphasis on
air discharging, the oil pump can be used as a pump to suck and discharge oil.
[0073] In this case, since the filter member 90 is arranged at the purge port 24, foreign
matter and the like accumulated in an oil pan can be prevented from being sucked into
the pump P. Therefore, sticking and the like of the upstream rotor 70 and the downstream
rotor 80 can be prevented and desired pump performance can be ensured. Further, improvement
of pump performance, improvement of durability, and the like can be achieved in a
wide engine revolution range.
[0074] In the description of the above embodiment, the present invention is applied to the
structure in which the rotor case 40, the side plate 50, and the like are arranged
at the inside of the housing (the housing body 10 and the housing cover 20) as a second
housing. However, not limited to the above, the present invention may be applied to
a structure without including the rotor case 40, the side plate 50, and the like.
[0075] In the description of the above embodiment, the present invention is applied to the
two-stage trochoid pump which includes the upstream rotor 70 (the first inner rotor
71 and the first outer rotor 72) and the downstream rotor 80 (the second inner rotor
81 and the second outer rotor 82). However, not limited to the above, the present
invention may be applied to a structure including one pair of an inner rotor and an
outer rotor.
[0076] In the description of the above embodiment, the present invention is applied to a
structure in which the housing is separated into the housing body and the housing
cover. However, not limited to the above, the present invention may be applied to
a structure in which a dual partitioning housing includes a first housing half body
and a second housing half body which define a concave portion respectively.
[0077] In the description of the above embodiment, the oil pump is a trochoid pump. However,
not limited to the above, the present invention may be adopted to an internal gear
type oil pump, an external gear type oil pump, or the like.
INDUSTRIAL APPLICABILITY
[0078] As described above, according to an oil pump of the present invention, even when
oil is sucked through a purge port, sticking and the like due to entering of foreign
matter and the like can be prevented and desired pump performance can be ensured.
Further, in a wide engine revolution range from a low revolution range to a high revolution
range including a revolution range having less air mixing, a revolution range having
less emphasis on air mixing, and the like, improvement of pump performance, improvement
of durability, and the like can be achieved. Accordingly, in addition to be naturally
adopted to an engine which is mounted on an automobile or the like, an oil pump of
the present invention is useful for motorcycles, other vehicles having an engine mounted,
other mechanisms requiring pressured feeding of lubricant oil, and the like.
EXPLANATION OF REFERENCES
[0079]
- 10
- Housing body (Housing)
- 11
- Bearing hole
- 12
- Inner circumferential face
- 13
- End face
- 14
- Inlet passage
- 15
- Discharge passage
- 16
- Positioning hole
- 17
- Joint face
- 18
- Screw hole
- 19
- Positioning hole
- 20
- Housing cover (Housing)
- 21
- Bearing hole
- 22
- Concave portion
- 23
- Concave portion
- 24
- Purge port
- 25
- Circular hole
- 26
- Positioning hole
- 27
- Positioning hole
- 28
- Counterbore portion
- 28'
- Ring-shaped groove
- 30
- Rotary shaft
- S
- Axis line
- 31
- One end portion
- 32
- Other end portion
- 33, 34, 35
- Shaft portion
- 40
- Rotor case
- 41
- Cylindrical portion
- 42
- Inner circumferential face
- 43
- Inner circumferential face
- 44
- Middle wall portion (Spacer member)
- 44a
- Bearing hole
- 44b
- Inlet port
- 44c
- Upstream rotor discharge port
- 44d
- Downstream rotor inlet port
- 44e
- Communication port
- 45
- End face
- 45a
- Positioning hole
- 46
- End face
- 46a
- Positioning hole
- 50
- Side plate
- 51
- Circular hole
- 52
- Discharge port
- 53
- Positioning hole
- 54
- Concave portion
- 60
- O-ring
- 70
- Upstream rotor
- P
- Pump chamber
- 71
- First inner rotor
- 71a
- Fitting hole
- 72
- First outer rotor
- L1
- Axis line
- 72a
- Outer circumferential face
- 80
- Downstream rotor
- P
- Pump chamber
- 81
- Second inner rotor
- 81a
- Fitting hole
- 82
- Second outer rotor
- L2
- Axis line
- 82b
- Outer circumferential face
- 90
- Filter member
- 91
- Fixing ring
- 91'
- Snap ring