U.S. patent application number 16/486175 was filed with the patent office on 2019-12-12 for electric oil pump.
The applicant listed for this patent is Nidec Tosok Corporation. Invention is credited to Takamitsu ETO, Hirotaka KANAMONO, Shigehiro KATAOKA, Yoshiyuki KOBAYASHI.
Application Number | 20190376511 16/486175 |
Document ID | / |
Family ID | 63370088 |
Filed Date | 2019-12-12 |
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United States Patent
Application |
20190376511 |
Kind Code |
A1 |
KOBAYASHI; Yoshiyuki ; et
al. |
December 12, 2019 |
ELECTRIC OIL PUMP
Abstract
An electric oil pump includes a motor, a pump, and a motor
driver. The pump includes a pump rotor attached to the shaft, a
pump body, and a pump cover. A motor driver includes an inverter
circuit that controls driving of a motor and an inverter cover. The
inverter circuit is in thermal contact with the pump cover.
Inventors: |
KOBAYASHI; Yoshiyuki;
(Zama-shi, JP) ; ETO; Takamitsu; (Zama-shi,
JP) ; KATAOKA; Shigehiro; (Zama-shi, JP) ;
KANAMONO; Hirotaka; (Zama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nidec Tosok Corporation |
Zama-shi, Kanagawa |
|
JP |
|
|
Family ID: |
63370088 |
Appl. No.: |
16/486175 |
Filed: |
February 23, 2018 |
PCT Filed: |
February 23, 2018 |
PCT NO: |
PCT/JP2018/006647 |
371 Date: |
August 15, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 2240/50 20130101;
F04C 29/047 20130101; F04C 15/0096 20130101; F04C 2240/40 20130101;
F04C 2240/60 20130101; F04C 11/008 20130101; H02K 11/33 20160101;
F04C 2240/808 20130101; F04C 15/0088 20130101; F04C 2210/206
20130101; F04C 2/102 20130101; H02K 7/14 20130101; F04C 2240/30
20130101 |
International
Class: |
F04C 15/00 20060101
F04C015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 2017 |
JP |
2017-040629 |
Claims
1-15. (canceled)
16: An electric oil pump comprising: a motor including a shaft
rotatable with respect to a central axis extending in an axial
direction; a pump that is positioned on a first side of the motor
in the axial direction, is driven by the shaft extending from the
motor, and discharges oil; and a motor driver that is positioned on
the first side of the motor in the axial direction via the pump and
drives the motor; wherein the motor includes: a rotor that is
rotatable around the shaft; a stator disposed on a side outward
from the rotor in a radial direction; and a housing that houses the
rotor and the stator; the pump includes: a pump rotor attached to
the shaft; a pump body including a recess that houses the pump
rotor and includes a side wall surface and a bottom surface
positioned on the second side of the motor in the axial direction,
and an opening on the first side of the motor in the axial
direction; and a pump cover that closes the opening; the motor
driver includes: an inverter circuit that controls driving of the
motor; and an inverter cover that covers the inverter circuit;
wherein the inverter circuit is in thermal contact with the pump
cover.
17: The electric oil pump according to claim 16, wherein an inlet
to take in the oil is provided at a position on the pump cover, and
an outlet to discharge the oil is provided in the pump cover on a
side opposite to the position of the inlet with respect to the
center axis.
18: The electric oil pump according to claim 16, wherein an inlet
to take in the oil is provided at a position on the pump cover, a
delivery port that communicates with the motor is provided in the
bottom surface of the recess on a side opposite to the position of
the inlet with respect to the center axis, and an outlet to
discharge the oil is provided on a bottom surface or a side surface
of the housing.
19: The electric oil pump according to claim 16, wherein an inlet
to take in the oil is provided at a position on the pump body, and
an outlet to discharge the oil is provided in the pump body on a
side opposite to the position of the inlet with respect to the
center axis.
20: The electric oil pump according to claim 16, wherein the pump
cover is in thermal contact with the inverter circuit via a heat
dissipation body.
21: The electric oil pump according to claim 17, wherein the
inverter circuit is disposed on an inlet side of the central
axis.
22: The electric oil pump according to claim 16, wherein the
inverter circuit includes a circuit board and a heater, and the
heater is in thermal contact with the inverter cover.
23: The electric oil pump according to claim 22, wherein the heater
of the inverter circuit is in thermal contact with the inverter
cover via a heat dissipation body.
24: The electric oil pump according to claim 22, wherein the heater
of the inverter circuit is disposed on an inlet side of the central
axis.
25: The electric oil pump according to claim 22, wherein the heater
of the inverter circuit includes a field effect transistor.
26: The electric oil pump according to claim 22, wherein the
circuit board of the inverter circuit is a copper-inlaid
substrate.
27: The electric oil pump according to claim 22, wherein the
circuit board of the inverter circuit includes a plurality of
substrates.
28: The electric oil pump according to claim 16, wherein the pump
body includes a bearing.
29: The electric oil pump according to claim 28, wherein the
bearing includes a ball bearing.
30: The electric oil pump according to claim 28, wherein the
bearing includes a sliding bearing.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a U.S. national stage of PCT Application No.
PCT/JP2018/006647, filed on Feb. 23, 2018, and priority under 35
U.S.C. .sctn. 119(a) and 35 U.S.C. .sctn. 365(b) is claimed from
Japanese Application No. 2017-040629, filed Mar. 3, 2017; the
entire disclosures of each application are hereby incorporated
herein by reference.
1. FIELD OF THE INVENTION
[0002] The present invention relates to an electric oil pump.
2. BACKGROUND
[0003] Continuously variable transmissions (CVT), dual clutch
transmissions (DCT), and the like have been known as transmissions
for automobiles and the like in recent years. Various forms of
transmissions have been discussed to improve fuel efficiency.
[0004] In addition, transmissions are required to have a function
of supplying oil by using a motor at the time of idle reduction or
the like, and an electric oil pump having an inverter circuit, a
motor, and a pump for realizing this function is required.
[0005] For example, Japanese Unexamined Patent Application
Publication No. 2015-175291 discloses an electric oil pump with a
structure in which a part of a pump cover in which an inverter
circuit is housed serves as a part of a transmission case.
[0006] However, since the electric oil pump disclosed in Japanese
Unexamined Patent Application Publication No. 2015-175291 has a
pump cover also serving as a part of the transmission case, the
structure of the electric oil pump is limited by the structure of
the transmission. Therefore, it is not possible to use the electric
oil pump with a structure including an inverter circuit, a motor,
and a pump generally in various transmissions.
[0007] In addition, in a case in which an electric oil pump is
required to exhibit higher output performance in terms of
responsiveness and the like, a quantity of heat from elements used
in the inverter circuit increases, and thus the inverter circuit
needs to be efficiently cooled.
SUMMARY
[0008] Example embodiments of the present disclosure provide
electric oil pumps each of which is usable for various
transmissions and achieves efficiently cooling of an inverter
circuit.
[0009] An electric oil pump according to an example embodiment of
the present disclosure includes a motor including a shaft rotatable
with respect to a central axis extending in an axial direction, a
pump that is located on a first side of the motor in the axial
direction, driven by the shaft extending from the motor, and
discharges oil, and a motor driver that is positioned on a second
side of the motor in the axial direction via the pump and drives
the motor, wherein the motor includes a rotor that is rotatable
around the shaft, a stator disposed on a side outward from the
rotor in a radial direction, and a housing that houses the rotor
and the stator, wherein the pump includes a pump rotor attached to
the shaft, a pump body including a recess that houses the pump
rotor and includes a side wall surface and a bottom surface
positioned on the second side of the motor in the axial direction,
and an opening on the first side of the motor in the axial
direction, and a pump cover that closes the opening, the motor
driver includes an inverter circuit that controls driving of the
motor, and an inverter cover that covers the inverter circuit, and
the inverter circuit is in thermal contact with the pump cover.
[0010] According to example embodiments of the present disclosure,
it is possible to provide electric oil pumps each usable for
various transmissions and efficiently cooling an inverter
circuit.
[0011] The above and other elements, features, steps,
characteristics and advantages of the present disclosure will
become more apparent from the following detailed description of the
example embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 illustrates a cross-sectional diagram of an electric
oil pump according to a first example embodiment of the present
disclosure.
[0013] FIG. 2 illustrates a cross-sectional diagram of a first
modified example of a motor drive unit of the present
disclosure.
[0014] FIG. 3 illustrates a cross-sectional diagram of a second
modified example of a motor drive unit of the present
disclosure.
[0015] FIG. 4 illustrates a cross-sectional diagram of a third
modified example of a motor drive unit of the present
disclosure.
[0016] FIG. 5 illustrates a cross-sectional diagram of a fourth
modified example of a motor drive unit of the present
disclosure.
[0017] FIG. 6 illustrates a cross-sectional diagram of a fifth
modified example of a motor drive unit of the present
disclosure.
[0018] FIG. 7 illustrates a cross-sectional diagram of a sixth
modified example of a motor drive unit of the present
disclosure.
[0019] FIG. 8 illustrates a cross-sectional diagram of a seventh
modified example of a motor drive unit of the present
disclosure.
[0020] FIG. 9 illustrates a cross-sectional diagram of an electric
oil pump according to a second example embodiment of the present
disclosure.
[0021] FIG. 10 illustrates a cross-sectional diagram of an electric
oil pump according to a third example embodiment of the present
disclosure.
[0022] FIG. 11 illustrates a cross-sectional diagram of an electric
oil pump according to a fourth example embodiment of the present
disclosure.
DETAILED DESCRIPTION
[0023] Electric oil pumps according to example embodiments of the
present disclosure will be described below with reference to the
drawings. In addition, scales, numerical values, and the like of
each structure may differ from those of actual structures in the
following drawings in order to facilitate understanding of
respective components.
[0024] In addition, an XYZ coordinate system is appropriately shown
in the drawings as a three-dimensional orthogonal coordinate
system. In an XYZ coordinate system, a Z axis direction is parallel
to the axial direction of the central axis J shown in FIG. 1. An X
axis direction is parallel to a direction in which a top board 63a
of an inverter cover 63 shown in FIG. 1 extends, that is, the
left-right direction of FIG. 1. A Y axis direction is orthogonal to
both the X axis direction and the Z axis direction.
[0025] Furthermore, in the following description, a positive side
of the Z axis direction (+Z side) will be referred to as a "front
side," and a negative side of the Z axis direction (-Z side) will
be referred to as a "rear side." Note that the rear side and the
front side are merely names used for description, and do not
restrict actual positional relationships and directions. In
addition, a direction parallel to the central axis J (Z axis
direction) will be referred to simply as an "axial direction," a
radial direction with respect to the central axis J will be
referred to simply as a "radial direction," and a circumferential
direction with respect to the central axis J, that is, a direction
around the central axis J (.theta. direction), will be referred to
simply as a "circumferential direction", unless specified
otherwise.
[0026] Note that, in the present specification, the phrase "in
thermal contact with" includes not only a case in which target
members are in direct contact with each other but also a case in
which members sandwich a member relating to heat conduction
therebetween. In addition, in the present specification, the phrase
"extending in the axial direction" includes extending in a
direction inclining from the axial direction by an angle in a range
less than 45.degree., as well as extending exactly in the axial
direction (Z axis direction). In addition, in the present
specification, the phrase "extending in the radial direction"
includes extending in a direction inclining from the radial
direction by an angle in a range less than 45.degree., as well as
extending exactly in the radial direction, that is, a direction
perpendicular to the axial direction (Z axis direction).
First Example Embodiment
<Overall Configuration>
[0027] FIG. 1 illustrates a cross-sectional diagram of an electric
oil pump according to the present example embodiment.
[0028] The electric oil pump 10 according to the present example
embodiment has a motor unit 20, a pump unit 30, and a motor drive
unit 60. The motor unit 20, the pump unit 30, and the motor drive
unit 60 are provided in a row in the axial direction.
[0029] The motor unit 20 has a shaft 41 that extends in the axial
direction and is supported to be rotatable around the central axis
J and causes the shaft 41 to rotate and thereby drives the pump.
The pump unit 30 is positioned on the front side (+Z side) of the
motor unit 20, is driven by the motor unit 20 via the shaft 41, and
discharges oil. The motor drive unit 60 is positioned on the front
side (+Z side) of the pump unit 30 and controls driving of the
motor unit 20.
[0030] Each of constituent members will be described below in
detail.
<Motor Unit 20>
[0031] The motor unit 20 has a housing 21, a rotor 40, a shaft 41,
a stator 50, and a bearing 55, as illustrated in FIG. 1.
[0032] The motor unit 20 is, for example, an inner rotor-type motor
in which the rotor 40 is fixed to an outer circumferential surface
of the shaft 41 and the stator 50 is positioned outward from the
rotor 40 in the radial direction. In addition, the bearing 55 is
disposed at an end of the shaft 41 on the rear side (-Z side) in
the axial direction and supports the shaft 41 to be rotatable.
(Housing 21)
[0033] The housing 21 has a bottomed thin cylindrical shape as
illustrated in FIG. 1 and has a bottom part 21a, a stator holding
part 21b, a pump body holding part 21c, a side wall part 21d, and
flange parts 24 and 25. The bottom part 21a constitute the bottom
portion, and the stator holding part 21b, the pump body holding
part 21c, and the side wall part 21d constitute a cylindrical side
wall surface with respect to the central axis J. In the present
example embodiment, an inner diameter of the stator holding part
21b is larger than that of the pump body holding part 21c. An outer
surface of the stator 50, that is, an outer surface of a core back
part 51 which will be described below, is fitted to an inner
surface of the stator holding part 21b. Accordingly, the stator 50
is housed in the housing 21. The flange part 24 spreads outward
from an end part of the side wall part 21d on the front side (+Z
side) in the radial direction. On the other hand, the flange part
25 spreads outward from an end part of the stator holding part 21b
on the rear side (-Z side) in the radial direction. The flange
parts 24 and 25 face each other and are fastened by a fastening
means, which is not illustrated. Accordingly, the motor unit 20 and
the pump unit 30 are sealed and fixed inside the housing 21.
[0034] For a material of the housing 21, for example, a
zinc-aluminum-magnesium-based alloy or the like can be used, and
specifically, steel sheets and strips plated with a molten
zinc-aluminum-magnesium alloy can be used. In addition, a bearing
holding part 56 for holding the bearing 55 is provided in the
bottom part 21a.
(Rotor 40)
[0035] The rotor 40 has a rotor core 43 and a rotor magnet 44. The
rotor core 43 surrounds the shaft 41 in the direction around the
axis (in the 0 direction) and is fixed to the shaft 41. The rotor
magnet 44 is fixed to an outer surface of the rotor core 43 in a
direction around the axis (in the 0 direction). The rotor core 43
and the rotor magnet 44 rotate along with the shaft 41.
(Stator 50)
[0036] The stator 50 surrounds the rotor 40 in a direction around
the axis (in the 0 direction) and causes the rotor 40 to rotate
around the central axis J. The stator 50 has the core back part 51,
tooth parts 52, a coil 53, and a bobbin (insulator) 54.
[0037] A shape of the core back part 51 is a cylindrical shape
concentric with the shaft 41. The tooth parts 52 extend from an
inner surface of the core back part 51 toward the shaft 41. A
plurality of tooth parts 52 are provided and are disposed on the
inner surface of the core back part 51 in a circumferential
direction at equal intervals. The coil 53 is provided around the
bobbing (insulator) 54 and a conductive wire 53a is wound
therearound. The bobbin (insulator) 54 is installed in each of the
tooth parts 52.
(Bearing 55)
[0038] The bearing 55 is disposed on the rear side (-Z side) of the
rotor 40 and the stator 50 and is held by the bearing holding part
56. The bearing 55 supports the shaft 41. A shape, a structure, and
the like of the bearing 55 are not particularly limited, and any
known bearing can also be used.
<Pump Unit 30>
[0039] The pump unit 30 is provided on one side of the motor unit
20 in the axial direction, specifically on the front side (+Z
side). The pump unit 30 has the same rotation axis as the motor
unit 20 and is driven by the motor unit 20 via the shaft 41. The
pump unit 30 has a positive displacement pump from which oil is
pressure-fed by enlarging and reducing the volume of a tightly
sealed space (an oil chamber). A trochoid pump, for example, may be
used as the positive displacement pump. The pump unit 30 has a pump
body 31, a pump cover 32, and a pump rotor 35. Note that a
combination of the pump body 31 and the pump cover 32 will also be
referred to as a pump case hereinafter.
(Pump Body 31)
[0040] The pump body 31 is positioned on the front side (+Z side)
of the motor unit 20. The pump body 31 has a main pump body 31b, a
through hole 31a penetrating through the inside of the main pump
body 31b along the axial direction of the central axis J, and a
projection part 31c projecting in a cylindrical shape from the main
pump body 31b on the front side (+Z side). An inner diameter of the
projection part 31c is larger than that of the through hole 31a.
The projection part 31c and the main pump body 31b constitute a
recess 33 that is open on the side toward the pump cover 32. The
through hole 31a is open toward the motor unit 20 on the rear side
(-Z side) and is open at the recess 33 on the front side (+Z side).
The through hole 31a functions as a bearing member that rotatably
supports the shaft 41 inserted thereinto. The recess 33 houses the
pump rotor 35 and functions as a pump chamber (which will also be
referred to as a pump chamber 33 hereinafter).
[0041] The pump body 31 is fixed inside the pump body holding part
21c on the front side (+Z side) of the motor unit 20. An O-ring 71
is provided between an outer circumferential surface of the main
pump body 31b and an inner circumferential surface of the pump body
holding part 21c in the radial direction. Accordingly, the gap
between the outer circumferential surface of the pump body 31 and
the inner circumferential surface of the housing 21 in the radial
direction is sealed.
[0042] Cast iron or the like, for example, can be used as a
material of the pump body 31.
(Pump Rotor 35)
[0043] The pump rotor 35 is attached to an end of the shaft 41 on
the front side (+Z side) and is housed in the pump chamber 33. The
pump rotor 35 has an inner rotor 37 attached to the shaft 41 and an
outer rotor 38 surrounding the outer side of the inner rotor 37 in
the radial direction.
[0044] The inner rotor 37 is an annular gear having teeth on the
outer surface thereof in the radial direction. The inner rotor 37
is fixed to the shaft 41 by press-fitting an end of the shaft 41 on
the front side (+Z side) thereinto. The inner rotor 37 rotates in
the direction around the axis (in the .theta. direction) along with
the shaft 41.
[0045] The outer rotor 38 surrounds the outer side of the inner
rotor 37 in the radial direction and is an annular gear having
teeth on an inner surface in the radial direction. The outer rotor
38 is rotatably housed in the pump chamber 33. The outer rotor 38
has an inner housing chamber (not illustrated) that houses the
inner rotor 37, the inner housing chamber being formed, for
example, in a star shape. The number of internal teeth of the outer
rotor 38 is greater than the number of external teeth of the inner
rotor 37.
[0046] The inner rotor 37 and the outer rotor 38 mesh with each
other, and when the inner rotor 37 rotates due to the shaft 41, the
outer rotor 38 rotates according to the rotation of the inner rotor
37. Since the inner rotor 37 and the outer rotor 38 rotate, the
volume of the space generated between the inner rotor 37 and the
outer rotor 38 changes depending on their rotation position. The
pump rotor 35 utilizes the change in the volume to take-in oil from
an inlet port 32c, which will be described below, applies a
pressure to the received oil, and discharges the oil to an outlet
port 32d. In the present example embodiment, a region in the space
generated between the inner rotor 37 and the outer rotor 38 in
which a volume increases (i.e., oil is taken-in) is called a
negatively pressurized region.
(Pump Cover 32)
[0047] The pump cover 32 is attached on the front side (+Z side) of
the pump body 31. The pump cover 32 has a main pump cover 32a, a
flange part 32b, the inlet port 32c, the outlet port 32d, an inlet
32e, and an outlet 32f.
[0048] The pump cover 32 is generally formed of a metal such as an
aluminum alloy and has a large heat capacity and surface area, and
thus the pump cover has a high heat radiating effect. In addition,
since oil having a temperature equal to or lower than a certain
temperature (e.g., 120.degree. C.) flows inside the pump cover 32,
an increase in temperature of the pump cover 32 is mitigated.
[0049] The main pump cover 32a has a disk shape extending in the
radial direction. The main pump cover 32a closes an opening of the
recess 33 on the front side (+Z side). The flange part 32b extends
from an outer edge on the front side (+Z side) of the main pump
cover 32a in the radial direction. An outer diameter of the pump
cover 32 is greater than that of the projection part 31c of the
pump body 31 since the pump cover 32 has the flange part 32b.
[0050] The inlet port 32c is a crescent-shaped groove when viewed
from the pump rotor 35 to the front side (+Z side). The inlet port
32c communicates with the pump rotor 35 on a degree that increases
with the increasing volume of the space generated between the inner
rotor 37 and the outer rotor 38. Likewise, the outlet port 32d also
is a crescent-shaped groove when viewed from the pump rotor 35 to
the front side (+Z side). The outlet port 32d communicates with the
pump rotor 35 on a degree that decreases with decreasing volume of
the space formed between the inner rotor 37 and the outer rotor
38.
[0051] The inlet 32e extends from the inlet port 32c toward a -X
side (to the left side of the drawing) within the main pump cover
32a and communicates with the outside. On the other hand, the
outlet 32f extends from the outlet port 32d toward an X side (the
right side of the drawing) within the main pump cover 32a and
communicates with an outside. The inlet 32e and the outlet 32f are
connected to the pump rotor 35 via the inlet port 32c and the
outlet port 32d respectively. Accordingly, intake of oil from the
pump rotor 35 and discharge of oil from the pump rotor 35 are
possible. More specifically, oil stored in the oil pan (not
illustrated) is taken into the pump chamber from the inlet 32e via
the inlet port 32c due to a negative pressure generated in the pump
chamber by rotation of the pump rotor 35. The taken oil is
discharged from a pressurized region to the outlet 32f via the
outlet port 32d.
<Motor Drive Unit 60>
[0052] The motor drive unit 60 is provided on the front side (+Z
side) of the pump cover 32 and controls driving of the motor unit
20. The motor drive unit 60 has the inverter cover 63 and an
inverter circuit 65 including a circuit board 61 and heating
elements 62.
(Inverter Circuit 65)
[0053] The inverter circuit 65 is obtained by mounting the heating
elements 62 on the circuit board 61, supplies power for driving, to
the coil 53 of the stator 50 of the motor unit 20, and controls
operations such as drive, rotation, stop, and the like of the motor
unit 20. In addition, supply of power and communication based on an
electrical signal between the motor drive unit 60 and the coil 53
of the stator 50 are performed by electrically connecting the motor
drive unit 60 and the coil 53 by using a wiring member such as a
coated cable, which is not illustrated.
[0054] The circuit board 61 outputs a motor drive signal. In the
present example embodiment, the circuit board 61 is directly
disposed on a surface of the pump cover 32 with ensured insulation.
Printed wiring, which is not illustrated, is provided on a surface
of the circuit board 61. In addition, by using a copper-inlaid
substrate as the circuit board 61, heat generated by the heating
elements 62 is more easily transmitted to the pump cover 32, and
thus cooling efficiency is improved.
[0055] The heating elements 62 are mounted on the front side (+Z
side) of the circuit board 61. The heating elements 62 are, for
example, capacitors, microcomputers, power ICs, field effect
transistors (FETs), or the like. In addition, the number of heating
elements 62 is not limited to two, and may be one or three or
more.
(Inverter Cover 63)
[0056] The inverter cover 63 is provided on the front side (+Z
side) of the pump cover 32 and covers the circuit board 61 and the
heating elements 62. The inverter cover 63 has the top board 63a
and a flange 63b.
[0057] The top board 63a is in contact with a surface of the
heating elements 62 on the front side (+Z side) and extends in the
radial direction. The flange 63b extends from an outer edge of the
top board 63a toward the rear side (-Z side). An end surface of the
flange 63b on the rear side (-Z side) comes in contact with a
surface of the flange part 32b of the pump cover 32 on the front
side (+Z side). Since the heating elements 62 of the inverter
circuit 65 are in direct contact with the top board 63a of the
inverter cover 63, heat generated by the heating elements 62 can be
dissipated from the inverter cover 63.
[0058] By fastening the flange 63b of the inverter cover 63 to the
flange part 32b of the pump cover 32 by using fastening means 64
such as a bolt and a nut, the inverter cover 63 is fixed to the
pump cover 32.
Action of Present Example Embodiment
[0059] (Operation of electric oil pump)
[0060] First, an operation when the electric oil pump 10 is
activated will be described.
[0061] In the electric oil pump 10 according to the present example
embodiment, first, power is supplied to the motor drive unit 60
from an external power source connected via a connector part, which
is not illustrated. Accordingly, a drive current is supplied to the
coil 53 of the stator 50 via a wiring member such as a coated
cable, which is not illustrated, from the motor drive unit 60. When
a drive current is supplied to the coil 53, a magnetic field is
generated, and the rotor core 43 and the rotor magnet 44 of the
rotor 40 rotate along with the shaft 41 due to the magnetic field.
In this operation, the electric oil pump 10 obtains a rotational
drive force.
[0062] The drive current supplied to the coil 53 of the stator 50
is controlled by power ICs circuit components, and the like, which
are the heating elements 62 of the inverter circuit 65 in the motor
drive unit 60. Specifically, the motor drive unit 60 detects a
rotational position of the rotor 40 by detecting a change of
magnetic flux of a sensor magnet (not illustrated) by a rotation
sensor, which is not illustrated. The inverter circuit 65 of the
motor drive unit 60 outputs a motor drive signal corresponding to a
rotational position of the rotor 40 and controls a drive current
supplied to the coil 53 of the stator 50. In this operation, drive
of the electric oil pump 10 of the present example embodiment is
controlled.
[0063] When power is supplied from the motor drive unit 60 to the
coil 53, a rotational magnetic field is generated by applying the
power to the coil 53, and thereby the rotor core 43 and the rotor
magnet 44 rotate. The rotation of the rotor 40 is transmitted to
the inner rotor 37 of the pump rotor 35 via the shaft 41, and
thereby the inner rotor 37 rotates. Accordingly, a negative
pressure is generated in the pump chamber 33 facing the inlet port
32c.
(Flow of Oil)
[0064] Next, a flow of oil will be described. The inlet 32e of the
electric oil pump 10 is connected to the oil pan (not illustrated)
in which oil is stored, via the circulation pipe (not illustrated),
and the tip of the circulation pipe on the oil pan side is immersed
in the oil. The oil stored in the oil pan passes through the inlet
32e, enters the inside of the electric oil pump 10, and reaches the
inlet port 32c due to a negative pressure generated by rotating the
inner rotor 37 of the electric oil pump 10. The oil taken from the
inlet port 32c into the pump chamber 33 is pressure-fed to the
outlet port 32d and discharged from the outlet port 32d to the
outlet 32f. The discharged oil is supplied to an inside of a
transmission, which is not illustrated. The supplied oil causes oil
pressure at a corresponding location and then flows back to be
stored in the oil pan again.
Effects of Present Example Embodiment
[0065] (1) The pump cover 32 is generally formed of a metal such as
an aluminum alloy, and has a large heat capacity and surface area,
and thus the pump cover has a high heat dissipation effect. In the
present example embodiment, the inverter circuit 65 is disposed on
the front side (+Z side) of the pump cover 32, and the circuit
board 61 is in direct contact with the main pump cover 32a having
the high heat dissipation effect, with ensured insulation.
Furthermore, a flow path of oil is created in the pump unit 30 from
the inlet 32e to the outlet 32f, and thus oil having a temperature
equal to or lower than a certain temperature (e.g., 120.degree. C.)
flows inside the pump cover 32.
[0066] Thus, heat generated in the circuit board 61 is effectively
cooled via the pump cover 32 and a temperature rise is restrained.
That is, since the pump cover 32 in contact with oil flowing inside
the pump unit 30 also performs a role as a heat sink by directly
cooling the circuit board 61 of the inverter circuit 65, cooling
can be effectively realized.
[0067] (2) In the present example embodiment, the heating elements
62 of the inverter circuit 65 are brought in direct contact with
the top board 63a of the inverter cover 63. For this reason, heat
generated by the heating elements 62 can also be dissipated from
the inverter cover 63. In addition, by using a copper-inlaid
substrate as the circuit board 61, heat generated in the inverter
circuit 65 is more easily transmitted to the pump cover 32, and
thus cooling efficiency is improved.
[0068] (3) The electric oil pump of the present example embodiment
comprises the motor unit 20, the pump unit 30, and the motor drive
unit 60 which are provided in a row in the axial direction and has
a compact cylindrical shape, and thus it can be generally used in
various transmissions.
[0069] (4) In the present example embodiment, some of oil taken-in
from the inlet 32e enters the gap between the through hole 31a of
the pump body 31 and the shaft 41 and lubricates a shaft support
part. That is, the through hole 31a functions as a sliding bearing
member that supports the shaft 41 to be rotatable by using the oil
flowing into the gap between the through hole 31a and the shaft 41.
However, in a case where a seal material or the like is disposed at
a predetermined location in order to prevent oil from entering into
the motor unit 20, a sliding bearing can be realized by using taken
oil, while preventing oil from entering into the motor unit 20.
[0070] Therefore, the shaft 41 has a double bearing structure due
to the above-described sliding bearing member of the pump unit 30
and the bearing 55 of the motor unit 20. Thus, even if the inner
rotor 37 receives a pressure caused by the oil, the double bearing
structure can mitigate an inclination of the shaft 41, and thus an
increase in sliding resistance can be restrained without causing
the inner rotor 37 to be pushed to a wall surface of the pump case
(i.e., the pump body 31 and the pump cover 32).
[0071] (5) In the present example embodiment, since the inlet 32e
and the outlet 32f are provided in the pump cover 32, cooling can
be performed at a position close to the inverter circuit 65, and
thus the cooling efficiency of the inverter circuit 65 is
enhanced.
Modified Examples of First Example Embodiment
Modified Examples in which Heat Dissipation Member is Provided
[0072] In the electric oil pump 10 according to the first example
embodiment illustrated in FIG. 1, the circuit board 61 of the
inverter circuit 65 is in direct contact with the main pump cover
32a with ensured insulation. However, the disclosure is not limited
to this structure, and for example, a heat dissipation member 66
relating to heat conduction can be sandwiched between the circuit
board 61 and the main pump cover 32a as illustrated in FIG. 2
(first modified example).
[0073] For the heat dissipation member 66, for example, a
thermosetting resin having a high heat conductivity such as
silicone rubber, a heat dissipation sheet, or a heat dissipation
gel can be used. In a case in which a thermosetting resin is used,
for example, after a resin is applied to the main pump cover 32a,
the circuit board 61 is assembled on the main pump cover 32a so as
to bring the circuit board 61 in pressure-contact with the resin,
and then the resin is cured. Accordingly, the inverter circuit 65
can be easily formed.
[0074] In this modified example, the circuit board 61 of the
inverter circuit 65 can be brought in contact with the main pump
cover 32a more reliably by using the heat dissipation member 66 so
that the cooling efficiency of the circuit board 61 can be
improved.
[0075] In addition, for example, positions of the circuit board and
the heating elements 62 may be reversed in the axial direction, the
heating elements 62 may be disposed on the rear side (-Z side)
further than the circuit board 61 and thus brought in contact with
the heat dissipation member 66, and meanwhile, the circuit board 61
may be brought in direct contact with the top board 63a of the
inverter cover 63 with ensured insulation, as illustrated in FIG. 3
(second modified example).
[0076] Since the heating elements 62 of the inverter circuit 65 can
be brought in contact with the main pump cover 32a via the heat
dissipation member 66 more reliably in this modified example,
cooling efficiency of the heating elements 62 can be improved. In
addition, since the circuit board 61 is brought in direct contact
with the top board 63a of the inverter cover 63 with ensured
insulation, heat generated in the circuit board 61 can also be
dissipated from the inverter cover 63.
[0077] Furthermore, for example, the heat dissipation member 66 can
be provided on the rear side (-Z side) of the top board 63a of the
inverter cover 63 in the motor drive unit 60 and can be brought in
contact with the heating elements 62, as illustrated in FIG. 4
(third modified example).
[0078] In this modified example, since the heat dissipation member
66 relating to heat conduction is sandwiched between the heating
elements 62 of the inverter circuit 65 and the top board 63a and
thereby the heating elements 62 can be brought in contact with the
top board 63a more reliably, heat of the heating elements is
effectively dissipated from the inverter cover 63 and a temperature
rise is restrained.
Modified Example in which Multiple Circuit Boards are Provided
[0079] In the first example embodiment illustrated in FIG. 1, an
example of the inverter circuit 65 having one circuit board 61 on
which two heating elements 62 of the same type are mounted has been
introduced. However, the disclosure is not limited to the inverter
circuit 65 having this structure, and for example, an inverter
circuit 65 having two circuit boards 61a and 61b on each of which
heating elements 62 are mounted as illustrated in FIG. 5 can also
be used (fourth modified example). In addition, the number of
circuit boards 61 may be two or three or more. Furthermore, the
number of heating elements 62 mounted on one circuit board 61 may
be plural, and heating elements of different kinds (e.g., any of
capacitors, microcomputers, power ICs, field effect transistors
(FETs), and the like) may be used.
[0080] According to this modified example, by using multiple
circuit boards 61 in the inverter circuit 65, a degree of freedom
of positions of the circuit boards when the circuit boards are
disposed in the motor drive unit 60 increases. With respect to a
circuit board 61 on which heating elements 62 generating a large
quantity of heat are mounted, for example, only the heating
elements 62 can be disposed on the main pump cover 32a side as
illustrated in FIG. 3. In addition, with respect to a circuit board
61 on which heating elements 62 having a large element size are
mounted, the disposition thereof can be changed if there is space
to do so. Accordingly, by changing disposition of the circuit board
61 in the motor drive unit 60 according to their characteristics,
heat dissipation and disposition in the space can be efficiently
achieved.
Modified Example in which Disposition of Inverter Circuit is
Changed
[0081] In the electric oil pump 10 according to the first example
embodiment illustrated in FIG. 1, the inverter circuit 65 is
disposed inside the motor drive unit 60 symmetrically with respect
to the central axis J. However, the disclosure is not limited to
this structure, and for example, a circuit board 61a and heating
elements 62 included in the inverter circuit 65 can be disposed on
the -X side (the left side of the drawing) from the central axis J
in the radial direction, as illustrated in FIG. 6 (fifth modified
example).
[0082] As illustrated in FIG. 1, in the pump unit 30, while the
inlet 32e is disposed on the -X side (the left side of the drawing)
from the central axis J in the radial direction, the outlet 32f is
disposed on the X side (the right side of the drawing) from the
central axis J in the radial direction. Oil having a low
temperature (e.g., 120.degree. C.) taken from the inlet 32e is
gradually heated by heat from the inverter circuit 65 until it
reaches the outlet 32f, and thus the temperature rises. Thus,
cooling efficiency of oil in the pump unit 30 serving as a heat
sink is lowered as it gets closer to the outlet 32f.
[0083] In this modified example, the circuit board 61a and the
heating elements 62 of the inverter circuit 65 are disposed on the
-X side (the left side of the drawing) from the central axis J in
the radial direction. Thus, the inverter circuit 65 can be cooled
with oil having a low temperature (e.g., 120.degree. C.) on the
inlet 32e side whose temperature has not yet increased due to heat
dissipation, and thus cooling efficiency is improved. Therefore,
effective cooling can be realized, for example, by disposing the
inverter circuit 65 including a field effect transistor (FET)
generating a large quantity of heat at the position.
Modified Example in which Disposition of Heating Element is
Changed
[0084] In the first example embodiment illustrated in FIG. 1, an
example of the inverter circuit 65 having one circuit board 61 on
which two heating elements 62 of the same type are mounted has been
introduced. However, the disclosure is not limited to the inverter
circuit 65 having this structure, and for example, an inverter
circuit 65 having a structure in which a part of a heating element
68 that is not mounted on a circuit board 61c is connected to the
circuit board 61c by using wiring 69, as illustrated in FIG. 7 can
also be used (sixth modified example).
[0085] In this modified example, in a case in which the heating
element 68 is an element generating a large quantity of heat, for
example, the heating element 68 is disposed directly on a main pump
cover 32a on the -X side (the left side of the drawing) from the
central axis J in the radial direction, thus cooling can be
performed by using oil having a low temperature (e.g., 120.degree.
C.) on the inlet 32e side, and therefore effective cooling can be
achieved.
[0086] Further, either or both of the heating element 68 and the
circuit board 61c may be disposed on the main pump cover 32a having
a heat dissipation member 66 relating to heat conduction interposed
therebetween.
[0087] In the above-described sixth modified example, an example in
which a part of the heating element 68 which is not mounted on the
circuit board 61c is disposed directly on a main pump cover 32a on
the -X side (the left side of the drawing) from the central axis J
in the radial direction has been described. However, for example, a
recess 32g may be provided at a part of the main pump cover 32a on
the -X side (the left side of the drawing) from the central axis J
in the radial direction, and the heating element 68 may be disposed
inside the recess 32g via a heat dissipation member 74 and
connected to the circuit board 61c by using wiring 75 as
illustrated in FIG. 8 (seventh modified example).
[0088] Since the heating element 68 is disposed inside the recess
32g, a surface area of the main pump cover 32a facing the heating
element 68 increases, and the heat dissipation effect is further
improved. In addition, a height of the heating element 68 in the
axial direction can be reduced by a height of the recess 32g, and
therefore the motor drive unit 60 can be made compact as a whole.
Although the heating element 68 can be housed directly in the
recess 32g, it is preferable to dispose the heating element 68
inside the recess 32g via the heat dissipation member 74.
[0089] For the heat dissipation member 74, for example, a
thermosetting resin having a high heat conductivity such as
silicone rubber, a heat dissipation sheet, or a heat dissipation
gel can be used. In a case in which a thermosetting resin is used,
for example, an appropriate amount of heat dissipation member 74 is
applied to the inside of the recess 32g, then the heating element
68 is fixed to the main pump cover 32a and is put into the recess
32g, and at the same time the heating element 68 is brought in
pressure-contact with the heat dissipation member 74. The inside of
the recess 32g can be easily filled with the heat dissipation
member 74 by curing the heat dissipation member 74 in the
above-described state. In addition, by forming irregularities on
the surface of the main pump cover 32a or the like, the surface
area can be increased, and heat dissipation effect can be further
improved.
[0090] Although a component having a high height and low heat
resistance, for example, a capacitor, can be exemplified as the
heating element 68 housed inside the recess 32g formed on the main
pump cover 32a side, other components may be used.
Second Example Embodiment
[0091] Next, an electric oil pump according to a second example
embodiment of the present disclosure will be described. In the
first example embodiment, an example in which the inlet 32e is
provided on the -X side (the left side of the drawing) of the pump
cover 32 from the central axis J in the radial direction and the
outlet 32f is provided on the X side (the right side of the
drawing) of the pump cover 32 from the central axis J in the radial
direction has been introduced. On the other hand, in the electric
oil pump of the present example embodiment, an outlet is formed at
a position different from that of the pump cover 32. Differences of
the present example embodiment from the first example embodiment
will be mainly described below. The electric oil pump according to
the present example embodiment will be given the same reference
numerals as those of the same configuration of the electric oil
pump according to the first example embodiment, and description
thereof will not be repeated.
[0092] FIG. 9 illustrates a cross-sectional diagram of the electric
oil pump according to the second example embodiment.
[0093] In the electric oil pump 100 according to the present
example embodiment, a delivery port 31d that extends from a bottom
of a recess 33 to a rear side (-Z side) and communicates with a
motor unit 20 is provided in a pump body 31 of a pump unit 30 on an
X side (the right side of the drawing) from a central axis J in a
radial direction. In addition, an outlet 73 from which oil is
discharged is provided on a bottom part 21a of a housing 21 at a
part of the X side (the right side of the drawing) from the central
axis J in the radial direction. Furthermore, an oil circulation
filter 76 is provided on the rear side (-Z side) of the outlet 73
if necessary. Further, the outlet 73 may be provided at a part of a
stator holding part 21b on the X side (the right side of the
drawing) from the central axis J in the radial direction, rather
than on the bottom part 21a of the housing 21.
Action of Present Example Embodiment
[0094] An operation when the electric oil pump device 100 according
to the present example embodiment is activated will not be
described since the operation is the same as the first example
embodiment, and so a flow of oil will be described.
[0095] An inlet 32e of the electric oil pump 10 is connected to the
oil pan (not illustrated) that stores oil, via the circulation pipe
(not illustrated), and the tip of the circulation pipe on the oil
pan side is immersed in the oil. The oil stored in the oil pan
passes through the inlet 32e, enters inside of the electric oil
pump 100, and reaches an inlet port 32c due to a negative pressure
generated by rotating the inner rotor 37 of the electric oil pump
100. The oil is taken from the inlet port 32c into a pump chamber
33, then is pressure-fed to the delivery port 31d, further passes
through the pump unit 30, and flows into the motor unit 20. In the
motor unit 20, the oil flows the gap between the inner
circumferential surface of the stator 50 and the outer
circumferential surface of the rotor 40 from the front side (+Z
side) to the rear side (-Z side) and is discharged to the outlet
73. Accordingly, the coil 53 of the stator 50 can be cooled with
higher efficiency and thus the rotor 40 can be cooled. The
discharged oil is supplied to an inside of a transmission, which is
not illustrated. The supplied oil causes oil pressure at a
corresponding location and then flows back to be stored in the oil
pan again.
Effect of Present Example Embodiment
[0096] (1) The pump cover 32 is generally formed of a metal such as
an aluminum alloy, and has a large heat capacity and surface area,
and thus the pump cover has a high heat dissipation effect. In the
present example embodiment, the inverter circuit 65 is disposed on
the front side (+Z side) of the pump cover 32, and the circuit
board 61 is in direct contact with the main pump cover 32a having
the high heat dissipation effect, with ensured insulation.
Furthermore, the flow path of oil is created in the pump unit 30
from the inlet 32e to the delivery port 31d, and thus oil having a
temperature equal to or lower than a certain temperature (e.g.,
120.degree. C.) flows inside the pump cover 32.
[0097] Thus, heat generated in the circuit board 61 is effectively
cooled via the pump cover 32 and a temperature rise is restrained.
That is, since the pump cover 32 in contact with oil flowing inside
the pump unit 30 also performs the role as a heat sink by directly
cooling the circuit board 61 of the inverter circuit 65, cooling
can be effectively realized.
[0098] (2) In the present example embodiment, the heating elements
62 of the inverter circuit 65 are brought in direct contact with
the top board 63a of the inverter cover 63. For this reason, heat
generated by the heating elements 62 can also be dissipated from
the inverter cover 63. In addition, by using a copper-inlaid
substrate as the circuit board 61, heat generated in the inverter
circuit 65 is more easily transmitted to the pump cover 32, and
thus cooling efficiency is improved.
[0099] (3) The electric oil pump of the present example embodiment
comprises the motor unit 20, the pump unit 30, and the motor drive
unit 60 which are each overlapped in the axial direction and has a
compact cylindrical shape, and thus it can be generally used in
various transmissions.
[0100] (4) Normally, a coil generates heat most intensely in a
motor. Heat generated by the coil is transmitted to the stator
core. That is, since the stator 50 generates a large amount of heat
in the motor unit 20, improving efficiency of cooling the stator 50
leads to improvement in cooling efficiency of the entire motor unit
20. In the present example embodiment, the rotor 40 and the stator
50 of the motor unit 20 can be cooled at the same time since oil
supplied from the outside is taken into the pump unit 30 from the
inlet 32e by a pump rotor 35, passes through the delivery port 31d,
and flows in the motor unit 20. Since the oil circulates the inside
of the motor unit 20 and absorbs heat generated by the motor, it
can prevent the motor from reaching an excessively high
temperature, and deterioration of rotation efficiency of the motor
can be avoided. That is, the electric oil pump device 100 in a
structure exhibiting a high cooling effect can be provided.
Modified Example of Second Example Embodiment
[0101] In the above-described example embodiment, the rotor 40 and
the stator 50 of the motor unit 20 can be cooled at the same time
by delivering oil to the inside of the motor unit 20 via the
delivery port 31d. However, a configuration without the delivery
port 31d can also be adoptable. In this case, the gap between the
shaft 41 and the pump body 31 in the axial direction may be used.
That is, the gap between the shaft 41 and the pump body 31 in the
axial direction can perform a role of a delivery port through which
oil is delivered from the pump unit 30 to the motor unit 20.
[0102] In this case, the through hole 31a functions as a sliding
bearing member that supports the shaft 41 to be rotatable.
[0103] According to a modified example described above, it is not
necessary to separately provide the delivery port 32d, and thus
processing becomes easier. In addition, oil flowing from the pump
unit 30 can be used as lubricating oil, and thus the oil can be
efficiently delivered into the motor unit 20.
[0104] Further, a notch may be provided on at least one of the
outer circumferential surface of the shaft 41 and the inner
circumferential surface of the pump body 31. Accordingly, when oil
passes between the shaft 41 and the pump body 31, flow path
resistance can be decreased, and thus oil can be more efficiently
delivered from the pump unit 30 to the motor unit 20.
[0105] In addition, another bearing can be used in the pump body
31, in addition to the above-described sliding bearing member. In
this case, oil may be allowed to pass through the bearing or a gap
between the shaft 41 and the bearing.
Third Example Embodiment
[0106] Next, an electric oil pump according to a third example
embodiment of the present disclosure will be described. In the
first example embodiment, an example in which the inlet 32e and the
outlet 32f are provided in the pump cover 32 has been introduced.
On the other hand, in the electric oil pump according to the
present example embodiment, an inlet 32e and an outlet 32f are
provided in the pump body 31. Differences of the present example
embodiment from the first example embodiment will be mainly
described below. The electric oil pump according to the present
example embodiment will be given the same reference numerals as
those of the same configuration of the electric oil pump according
to the first example embodiment, and description thereof will not
be repeated.
[0107] FIG. 10 illustrates a cross-sectional diagram of the
electric oil pump according to the third example embodiment of the
present disclosure.
[0108] In the electric oil pump 110 according to the present
example embodiment, the inlet 32e extends inside the projection
part 31c of the pump body 31 from the pump chamber 33 toward the -X
side (the left side of the drawing) and reaches the outer surface
of the projection part 31c. On the other hand, the outlet 32f
extends inside the projection part 31c in the pump body 31 from the
pump chamber 33 to the X side (the right side of the drawing) and
reaches the outer surface of the projection part 31c.
[0109] The inlet 32e and the outlet 32f are connected to a pump
rotor 35 via the inlet port 32c and the outlet port 32d
respectively. Accordingly, the configuration makes intake of oil to
the pump rotor 35 and discharge of oil from the pump rotor 35
possible. Specifically, oil stored in the oil pan (not illustrated)
is taken into the pump chamber from the inlet 32e via the inlet
port 32c due to a negative pressure generated in the pump chamber
by rotation of the pump rotor 35. The taken oil is discharged from
the pressurized region to the outlet 32f via the outlet port
32d.
[0110] The electric oil pump 110 according to the present example
embodiment exhibits the same action and effects as the electric oil
pump 10 according to the first example embodiment. In addition,
since the inlet 32e and the outlet 32f are provided in the pump
body 31 in the present example embodiment, the effects is better
exhibited when heat that has moved to the pump body 31 is
cooled.
Fourth Example Embodiment
[0111] Next, an electric oil pump according to a fourth example
embodiment of the present disclosure will be described. In the
present example embodiment, a bearing unit is provided in the pump
body 31. Differences of the present example embodiment from the
first example embodiment will be mainly described below. The
electric oil pump according to the present example embodiment will
be given the same reference numerals as those of the same
configuration of the electric oil pump according to the first
example embodiment, and description thereof will not be
repeated.
[0112] FIG. 11 illustrates a cross-sectional diagram of the
electric oil pump according to the fourth example embodiment.
[0113] The electric oil pump 120 according to the present example
embodiment includes a ball bearing 31f serving as a bearing unit
that supports the shaft 41 on the rear side (-Z side) of the main
pump body 31b.
[0114] The ball bearing 31f is fitted in the recess 31g provided in
the main pump body 31b and is fixed by the main pump body 31b in a
circumferential direction of the ball bearing 31f. That is, the
main pump body 31b also serves as a bearing holder in the present
example embodiment.
[0115] Thus, since it is not necessary to provide a new region in
the main pump body 31b which a bearing holder is to be installed,
an effective volume of the pump body can be increased. Thus, a heat
capacity can be increased, and heat dissipation of an inverter
circuit becomes easier.
[0116] In addition, the shaft 41 has a double bearing structure of
the ball bearing 31f and the bearing 55 of the motor unit 20 in the
present example embodiment. Thus, even if the inner rotor 37
receives a pressure caused by oil, the double bearing structure can
mitigate an inclination of the shaft 41, an increase in sliding
resistance can be restrained without causing the inner rotor 37 to
be pushed to a wall surface of the pump case (i.e., the pump body
31 and the pump cover 32).
[0117] Furthermore, since the inlet 32e and the outlet 32f are
provided in the pump cover 32 in the present example embodiment as
in the first example embodiment, oil flows closer to the inverter
circuit 65 in comparison to the third example embodiment in which
the inlet 32e and the outlet 32f are provided in the pump body 31,
and thus heat generated in the inverter circuit 65 can be
effectively cooled.
[0118] Further, although an example in which the ball bearing 31f
serves as a bearing unit has been introduced in the present example
embodiment, another structure functioning as a bearing unit may be
adopted. For example, a sliding bearing member as described in the
first example embodiment and a modified example of the second
example embodiment can be used instead of or together with the ball
bearing 31f.
[0119] Although several example embodiments of the present
disclosure have been described above, the example embodiments are
merely examples and do not intend to limit the scope of the
disclosure. Their example embodiments can be implemented in various
other modes, and can be subject to omission, substitution,
modification in various forms within a scope not departing from the
subject matter of the disclosure. Their example embodiments and
modifications are included within the scope of the disclosures
described in the claims and equivalents thereto, as included in the
scope and the subject matter of the disclosure.
[0120] Although, in the pump unit 30 of the first example
embodiment, the inlet 32e is provided on the -X side (the left side
of the drawing) from the central axis J in the radial direction,
and the outlet 32f is provided on the X side (the right side of the
drawing) from the central axis J in the radial direction, for
example, the disposition of the inlet 32e and the disposition of
the outlet 32f can be reversed. In this case, for the modified
examples of the first example embodiment in which the inverter
circuit 65 is asymmetrically disposed with respect to the central
axis J (FIG. 6 to FIG. 8), the inverter circuit 65 can be disposed
in a reverse direction to the central axis J. In addition, the
disposition of the inverter circuit 65 according to the modified
examples of the first example embodiment is also applicable to the
second and fourth example embodiments. Furthermore, while the inlet
32e is provided in the pump cover 32 in the second example
embodiment, the inlet 32e can also be provided in the pump body 31
as in the third example embodiment. In addition, a length, a shape,
an inner diameter, and the like of the inlet 32e and the outlet
32f, and a shape, a width, a height, and the like of the inlet port
32c and the outlet port 32d according to the first and fourth
example embodiments, and a length, a shape, an inner diameter, and
the like of the delivery port 31d according to the second example
embodiment can be appropriately changed if necessary.
[0121] This application claims the benefits of priority based on
Japanese Patent Application No. 2017-040629, filed on Mar. 3, 2017,
the content of which is incorporated herein by reference.
[0122] While example embodiments of the present disclosure have
been described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present disclosure. The
scope of the present disclosure, therefore, is to be determined
solely by the following claims.
* * * * *