U.S. patent application number 14/375981 was filed with the patent office on 2015-01-08 for oil pump.
The applicant listed for this patent is MIKUNI CORPORATION. Invention is credited to Hiroyuki Oda.
Application Number | 20150010420 14/375981 |
Document ID | / |
Family ID | 48905324 |
Filed Date | 2015-01-08 |
United States Patent
Application |
20150010420 |
Kind Code |
A1 |
Oda; Hiroyuki |
January 8, 2015 |
OIL PUMP
Abstract
An oil pump of the present invention includes a housing (10, 20)
which includes an inlet port (44b) to suck oil, a discharge port
(52) to discharge oil, and a purge port (24) to eject air-mixed
oil, an inner rotor (71, 81) which is arranged in the housing as
being rotatable about a predetermined axis line (S), an outer rotor
(72, 82) which is arranged in the housing to be rotated as being
interlocked with the inner rotor, and a filter member (90) which is
arranged at the housing from the outside thereof to prevent foreign
matter from entering through the purge port. According to the
above, entering of foreign matter and the like can be prevented
even when oil is sucked through the purge port.
Inventors: |
Oda; Hiroyuki; (Iwate,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MIKUNI CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
48905324 |
Appl. No.: |
14/375981 |
Filed: |
January 31, 2013 |
PCT Filed: |
January 31, 2013 |
PCT NO: |
PCT/JP2013/052131 |
371 Date: |
July 31, 2014 |
Current U.S.
Class: |
418/166 |
Current CPC
Class: |
F04C 15/064 20130101;
F04C 2220/20 20130101; F04C 2/102 20130101; F04C 2280/02 20130101;
F04C 14/28 20130101 |
Class at
Publication: |
418/166 |
International
Class: |
F04C 15/06 20060101
F04C015/06; F04C 2/10 20060101 F04C002/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 3, 2012 |
JP |
2012-021728 |
Claims
1. An oil pump, comprising: 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.
2. The oil pump according to claim 1, wherein 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.
3. The oil pump according to claim 1, wherein 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.
4. The oil pump according to claim 1, wherein 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.
5. The oil pump according to claim 4, wherein the inlet port is
arranged at the spacer member between the upstream rotor and the
downstream rotor to be faced to the upstream rotor.
6. The oil pump according to claim 1, wherein the inner rotor and
the outer rotor are formed in four blades and five nodes.
7. The oil pump according to claim 1, wherein 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.
Description
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
[0006] Patent Literature 2: Japanese Patent Application Laid-Open
No. 6-167278
[0007] Patent Literature 2: Japanese Utility-model Application No.
2-107738 (Japanese Utility-model Application Laid-open No. 4-65974)
(Microfilm)
SUMMARY OF THE INVENTION
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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 maybe 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] According to the configuration, ejection of air through the
purge port can be effectively performed.
[0024] 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
[0025] FIG. 1 is a front view illustrating an embodiment of an oil
pump according to the present invention.
[0026] FIG. 2 is a sectional view illustrating the inside of the
oil pump illustrated in FIG. 1.
[0027] FIG. 3 is a front view illustrating a housing body which
structures a part of the oil pump illustrated in FIG. 1.
[0028] 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).
[0029] FIG. 4B is a sectional view of the housing cover which
structures apart of the oil pump illustrated in FIG. 1 at E1-E1 in
FIG. 4A.
[0030] 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.
[0031] FIG. 6 is a sectional view illustrating a rotor case which
structures a part of the oil pump illustrated in FIG. 1.
[0032] FIG. 7A is an end view of the rotor case illustrated in FIG.
6 viewed from the front F side.
[0033] FIG. 7B is an end view of the rotor case illustrated in FIG.
6 viewed from the rear R side.
[0034] 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.
[0035] FIG. 8B is a sectional view of the side plate which
structures apart of the oil pump illustrated in FIG. 1 at E2-E2 in
FIG. 8A.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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
[0040] In the following, embodiments of the present invention will
be described with reference to the attached drawings.
[0041] 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.
[0042] 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 rotatably 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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.
[0068] 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.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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.
[0073] 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).
[0074] 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.
[0075] 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.
[0076] 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.
[0077] 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).
[0078] 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.
[0079] 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.
[0080] 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.
[0081] 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).
[0082] Next, operation of the oil pump will be described with
reference to FIGS. 9A, 9B and 10.
[0083] 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.
[0084] 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.
[0085] 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).
[0086] 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.
[0087] 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.
[0088] 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.
[0089] 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.
[0090] 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.
[0091] 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.
[0092] 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.
[0093] 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
[0094] 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
[0095] 10 Housing body (Housing) [0096] 11 Bearing hole [0097] 12
Inner circumferential face [0098] 13 End face [0099] 14 Inlet
passage [0100] 15 Discharge passage [0101] 16 Positioning hole
[0102] 17 Joint face [0103] 18 Screw hole [0104] 19 Positioning
hole [0105] 20 Housing cover (Housing) [0106] 21 Bearing hole
[0107] 22 Concave portion [0108] 23 Concave portion [0109] 24 Purge
port [0110] 25 Circular hole [0111] 26 Positioning hole [0112] 27
Positioning hole [0113] 28 Counterbore portion [0114] 28'
Ring-shaped groove [0115] 30 Rotary shaft [0116] S Axis line [0117]
31 One end portion [0118] 32 Other end portion [0119] 33, 34, 35
Shaft portion [0120] 40 Rotor case [0121] 41 Cylindrical portion
[0122] 42 Inner circumferential face [0123] 43 Inner
circumferential face [0124] 44 Middle wall portion (Spacer member)
[0125] 44a Bearing hole [0126] 44b Inlet port [0127] 44c Upstream
rotor discharge port [0128] 44d Downstream rotor inlet port [0129]
44e Communication port [0130] 45 End face [0131] 45a Positioning
hole [0132] 46 End face [0133] 46a Positioning hole [0134] 50 Side
plate [0135] 51 Circular hole [0136] 52 Discharge port [0137] 53
Positioning hole [0138] 54 Concave portion [0139] 60 O-ring [0140]
70 Upstream rotor [0141] P Pump chamber [0142] 71 First inner rotor
[0143] 71a Fitting hole [0144] 72 First outer rotor [0145] L1 Axis
line [0146] 72a Outer circumferential face [0147] 80 Downstream
rotor [0148] P Pump chamber [0149] 81 Second inner rotor [0150] 81a
Fitting hole [0151] 82 Second outer rotor [0152] L2 Axis line
[0153] 82b Outer circumferential face [0154] 90 Filter member
[0155] 91 Fixing ring [0156] 91' Snap ring
* * * * *