PUMP ASSEMBLY

A pump assembly includes an axial gap motor including a first stator, a motor rotor and a motor shaft, and a first pump including a first pump rotor configured to be rotated by the motor rotor. The first stator includes a first yoke having an annular shape and a plurality of first teeth disposed on a first surface of the first yoke. The first pump is disposed in a first internal space surrounded by the plurality of first teeth.

TECHNICAL FIELD

The present disclosure relates to a pump assembly. This application claims priority based on Japanese Patent Application No. 2022-202207 filed on Dec. 19, 2022, and the entire contents of the Japanese patent application are incorporated herein by reference.

BACKGROUND ART

An axial gap motor has a stator, a motor rotor, and a motor shaft. In the axial gap motor, the magnetic flux from the stator to the rotor flows in parallel to the axis of the motor shaft. The axial gap motor has an advantage of a small length along the axis.

PTL 1 discloses a pump assembly combining an axial gap motor and an electric pump for pumping a fluid. In this pump assembly, the axial gap motor and the electric pump are arranged side by side in a direction along the axis of a motor shaft. Such a pump assembly is compact, taking advantage of the small axial gap motor size along the axis. In the pump assembly using a radial gap motor, the size of the motor shaft along the axis is large.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

A pump assembly of the present disclosure includes an axial gap motor including a first stator, a motor rotor and a motor shaft, and a first pump including a first pump rotor configured to be rotated by the motor rotor. The first stator includes a first yoke having an annular shape and a plurality of first teeth disposed on a first surface of the first yoke. The first pump is disposed in a first internal space surrounded by the plurality of first teeth.

DETAILED DESCRIPTION

Problems to be Solved by Present Disclosure

The pump assembly may be disposed in a narrow space such as a space in an automobile. Therefore, even when the axial gap motor is used, a pump assembly having a more compact length along the axis is required.

One object of the present disclosure is to provide a pump assembly that is more compact in size along the axis of the motor shaft than conventional pump assemblies.

Advantageous Effects of Present Disclosure

The pump assembly of the present disclosure is more compact than conventional pump assemblies.

Description of Embodiments of Present Disclosure

<1> A pump assembly of the present disclosure includes an axial gap motor including a first stator, a motor rotor and a motor shaft, and a first pump including a first pump rotor configured to be rotated by the motor rotor. The first stator includes a first yoke having an annular shape and a plurality of first teeth disposed on a first surface of the first yoke. The first pump is disposed in a first internal space surrounded by the plurality of first teeth.

In the pump assembly described in the <1>, the first pump is disposed in the first internal space of the axial gap motor surrounded by the plurality of first teeth. Therefore, the length of the motor shaft along the axis in the pump assembly described in the <1> is smaller than the length of the motor shaft along the axis in the conventional pump assembly.

In the pump assembly described in the <1>, the first pump is disposed in the first internal space. That is, the first pump is disposed inside the axial gap motor and is surrounded by constituent members of the axial gap motor. Therefore, the operating noise of the first pump is unlikely to leak to the outside of the pump assembly. Therefore, the pump assembly described in the <1> is excellent in quietness.

In the pump assembly described in the <1>, the temperature of the first pump disposed in the first internal space of the axial gap motor is likely to rise due to the heat generation of the axial gap motor. When the temperature of the first pump rises, the temperature of the fluid in the first pump rises, and the viscosity of the fluid decreases. As a result, the load of the axial gap motor is reduced, and the power consumption of the axial gap motor is reduced. In particular, after the start of the axial gap motor in which the temperature of the fluid is low, the load of the axial gap motor is likely to be reduced at an early stage. The first pump disposed in the first internal space has a high heat capacity due to its structure. Therefore, the first pump easily receives heat generated by the axial gap motor, and can suppress heat generation of the axial gap motor. The fluid in the present disclosure may be a liquid, a gas, or a mixture of a gas and a liquid.

<2> In the pump assembly according to <1>, the first pump rotor may be coaxially fixed to the motor shaft.

In the pump assembly described in the <2>, the motor shaft of the motor rotor also serves as a drive shaft of the pump rotor. Therefore, the number of parts of the pump assembly is reduced, and the pump assembly is more compact. Further, since the first pump rotor rotates in complete synchronization with the rotation of the motor rotor, the number of rotations of the first pump rotor, that is, the flow rate of the fluid, can be easily controlled by the axial gap motor.

<3> In the pump assembly according to <1> or <2>, the first pump may have an inlet port and an outlet port. The inlet port and the outlet port may be arranged in a first direction as viewed from the first pump rotor. The first direction is a direction along an axis of the motor shaft and is a direction away from the motor rotor.

Since the motor rotor does not exist in the first direction as viewed from the first pump rotor, the inlet port and the outlet port can be easily arranged. Further, since the inlet port and the outlet port are arranged in the first direction, an increase in the diameter of a stator core is suppressed.

Unlike the configuration described in the <3>, when the inlet port and the outlet port are arranged in the radial direction, the inlet port and the outlet port are arranged in a gap between a plurality of first teeth arranged in the first yoke having an annular shape. The radial direction is a direction orthogonal to the axis of the motor shaft and is a direction away from the axis. The inlet port and the outlet port along the radial direction increase the interval between the plurality of first teeth, and thus the diameter of the stator core is likely to increase.

<4> In the pump assembly according to any one of <1> to <3>, the first pump may be an internal gear pump including an external gear and an internal gear. The external gear may be the first pump rotor.

The internal gear pump with the external gear disposed inside the internal gear is compact. The internal gear pump is easily disposed in the first internal space having a size restriction. Also, the internal gear pump is more space efficient than other pumps of the same size. Therefore, the pump assembly described in the <4> is compact and can easily increase the flow rate of the fluid.

<5> In the pump assembly according to <4>, the axial gap motor may include a motor housing configured to house the first stator and the motor rotor. The internal gear pump may include a pump housing configured to house the external gear and the internal gear. The motor housing includes a base portion to which the first yoke is fixed. The pump housing includes a body, a pump cover, and a bolt. The body includes a cylindrical portion, a bottom portion, and an annular flange portion, the cylindrical portion being configured to cover an outer periphery of the internal gear, the bottom portion being configured to seal a first end surface of the cylindrical portion, and the annular flange portion extending toward an outside of the cylindrical portion from an outer peripheral surface of the cylindrical portion at a position near a second end surface of the cylindrical portion. The pump cover is configured to seal an opening of the cylindrical portion at the second end surface. The bolt is configured to fix the pump cover to the annular flange portion. The annular flange portion constitutes the base portion.

In the configuration described in the <5>, the pump cover of the pump housing is fixed to the annular flange portion integrated with the body of the pump housing by the bolt. Therefore, it is not necessary to provide a bolt hole for disposing the bolt in the cylindrical portion covering the outer periphery of the internal gear. The cylindrical portion, which does not require a bolt hole, can be made thin. The outer diameter of the cylindrical portion can be reduced or the inner diameter of the cylindrical portion can be increased by the amount of the reduction in the thickness of the cylindrical portion. If the outer diameter of the cylindrical portion is reduced without changing the inner diameter of the cylindrical portion, the outer diameter of the pump assembly can be reduced without reducing the capacity of the internal gear pump. If the inner diameter of the cylindrical portion is increased without changing the outer diameter of the cylindrical portion, the capacity of the internal gear pump can be increased without increasing the outer diameter of the pump assembly.

<6> In the pump assembly according to any one of <1> to <3>, the first pump may be a vane pump. The first pump rotor may include a plurality of vanes.

The vane pump having the first pump rotor with a plurality of vanes is compact. The vane pump is easily disposed in the first internal space having a size restriction. Further, the vane pump has excellent sealing performance, and therefore, can easily pump even a gas, a liquid, or a mixture of a gas and a liquid.

<7> In the pump assembly according to any one of <1> to <6>, the pump assembly may further include a second pump including a second pump rotor configured to be rotated by the motor rotor. The axial gap motor may further include a second stator disposed such that the motor rotor is interposed between the first stator and the second stator. The second stator includes a second yoke having an annular shape and a plurality of second teeth disposed on a second surface of the second yoke. The second pump is disposed in a second internal space surrounded by the plurality of second teeth.

An axial gap motor in which one motor rotor is interposed between a first stator and a second stator generates high torque. Such an axial gap motor is called an axial gap motor of single-rotor and double-stator type. The pump assembly described in the <7> includes a first pump and a second pump which are independent from each other. Therefore, the pump assembly described in the <7> can pressure-feed, for example, fluids of two independent systems. Further, since the first pump and the second pump are respectively disposed in the first internal space and the second internal space in the axial gap motor, the pump assembly described in the <7> is compact.

Details of Embodiments of Present Disclosure

Hereinafter, specific examples of the pump assembly of the present disclosure will be described with reference to the drawings. In the drawings, the same reference numerals denote the same or corresponding parts. The size of the members shown in the drawings is expressed for the purpose of clarifying the description, and does not necessarily represent the actual size. The present invention is not limited to these examples, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

First Embodiment

A pump assembly1shown inFIGS.1and2includes an axial gap motor2and a first pump5. A motor housing29of axial gap motor2and a pump housing59of first pump5are visible from the outside of pump assembly1. An inlet port51and an outlet port52are opened in pump housing59. As shown in the plan view ofFIG.2, an external gear55and an internal gear56provided in first pump5, which will be described later, are seen behind inlet port51and outlet port52. Hereinafter, each configuration of pump assembly1will be described. In the following description, the “axial gap motor” is simply referred to as a “motor”.

In the description of motor2,FIG.3, which is an exploded perspective view of motor2, is mainly referred to, andFIGS.5and6, which are cross-sectional views of pump assembly1, are referred to as necessary. Motor2includes a first stator4, a motor rotor3, and a motor shaft20. As shown inFIGS.5and6, first stator4and motor rotor3are disposed coaxially with motor shaft20. First stator4and motor rotor3face each other with a gap therebetween in a direction along the axis of motor shaft20. Motor2of the present embodiment is a motor of single-rotor and single-stator type including one first stator4and one motor rotor3.

First stator4includes a first yoke40, a plurality of first teeth41, and a plurality of first coils42. First yoke40is a plate member formed in an annular shape. First teeth41are columnar bodies. First teeth41protrude from a first surface40shaving a planar shape of first yoke40. The plurality of first teeth41have the same shape and size. The shape of each first teeth41is, for example, a prismatic shape or a cylindrical shape. First stator4of the present embodiment is constituted by, for example, an integrated powder compact. As a modification of the present embodiment, first stator4may be constituted by a plurality of divided pieces.

The end surface of first teeth41faces a magnet31of motor rotor3, which will be described later. First coil42is disposed on the outer peripheral surface of first teeth41. When the current flows through first coil42, first stator4is excited, and a rotating magnetic field is generated. In the present embodiment, the end portions of the winding constituting first coil42are not shown.

Motor rotor3includes a base plate30and a plurality of magnets31. Base plate30is a plate member having a circular shape through which motor shaft20penetrates. Base plate30and motor shaft20are fixed to each other, and base plate30and motor shaft20rotate coaxially. Base plate30includes a base surface30sfacing first surface40sof first yoke40.

The plurality of magnets31are fixed to base surface30swith an adhesive, for example. Magnet31is a permanent magnet. The plurality of magnets31are arranged at substantially equal intervals around the axis of motor shaft20. Magnet31has, for example, a flat plate shape. The planar shape of magnet31is, for example, a shape corresponding to the shape of the end surface of first teeth41. Magnet31is magnetized in a direction along the axis of motor shaft20. The magnetization directions of two magnets31adjacent to each other around the axis of motor shaft20are opposite to each other. Magnet31is attracted to or repelled from first teeth41by the rotating magnetic field generated by first stator4, whereby motor rotor3rotates with respect to first stator4.

As shown inFIG.5, motor2further includes motor housing29. First stator4and motor rotor3are disposed inside motor housing29. A part of motor shaft20is also disposed inside motor housing29. As a modification of the present embodiment, entire motor shaft20may be disposed inside motor housing29.

Motor housing29of the present embodiment constituted by a peripheral wall portion2A, a first cover2B, and a second cover2C. Peripheral wall portion2A is a cylindrical member. The inner diameter of peripheral wall portion2A is larger than the outer diameter of first stator4. The length of peripheral wall portion2A along motor shaft20is greater than the length of first stator4along motor shaft20.

First cover2B is a member having a disc-shape that seals a first end portion of peripheral wall portion2A. First cover2B is a component independent of peripheral wall portion2A. The first end portion is an end portion of first stator4adjacent to first yoke40. First yoke40is fixed to first cover2B. That is, first cover2B functions as a base portion2Bb to which first stator4is fixed. A part of first cover2B of the present embodiment constitutes a first cover5B of pump housing59described later. First cover2B is provided with a flange at the edge of the outer periphery. The protruding height of pump housing59is the same as or lower than the end surface of the flange. Therefore, the protruding portion of pump housing59is housed in a recess space formed inside the flange of first cover2B.

Second cover2C is a member having a circular shape that seals a second end portion of peripheral wall portion2A. The second end portion is an end portion opposite to the first end portion. Second cover2C may be a component independent of peripheral wall portion2A or may be a component integrated with peripheral wall portion2A. In the present embodiment, peripheral wall portion2A and second cover2C are integrated by fitting second cover2C prepared separately from peripheral wall portion2A into peripheral wall portion2A. Therefore, motor shaft20penetrates second cover2C. A bearing25is disposed between second cover2C and motor shaft20, and motor shaft20is rotatably supported by second cover2C. A seal member for suppressing leakage of fluid from motor housing29may be disposed at the position of bearing25. As a modification of the present embodiment, when entire motor shaft20is disposed in motor housing29, the inner surface of second cover2C includes a recess into which the end portion of motor shaft20is fitted.

First pump5will be described mainly with reference toFIGS.4to6.FIG.4is a view for explaining the arrangement state of first pump5in pump assembly1, and some members of pump assembly1are omitted or simplified. For example, inFIG.4, first cover2B of motor housing29and motor rotor3are omitted. InFIG.4, first cover5B (FIGS.5and6) of pump housing59described later is omitted, and a state where the inside of first pump5is exposed is shown. InFIG.4, first stator4, inlet port51, and outlet port52are shown by two dot chain lines.

First pump5is for pumping the fluid. The fluid of the present embodiment is a liquid. For example, the fluid is machine oil. First pump5includes a first pump rotor50configured to be rotated by motor rotor3. First pump5is disposed in a first internal space21surrounded by the plurality of first teeth41.

First pump5of the present embodiment is an internal gear pump having external gear55and internal gear56. External gear55is a disc-shaped gear having teeth on an outer periphery. The tooth profile of external gear55is formed by, for example, a trochoid curve. Internal gear56is a gear having a circular shape and teeth on the inner periphery. External gear55is disposed inside internal gear56, and the teeth of external gear55and the teeth of internal gear56mesh with each other. In this internal gear pump, external gear55is first pump rotor50.

External gear55and internal gear56are disposed inside pump housing59. As shown inFIGS.5and6, pump housing59of the present embodiment is constituted by a peripheral wall portion5A, first cover5B, and a second cover5C. Peripheral wall portion5A is a member having a tubular shape. As shown inFIG.4, the outer periphery contour of peripheral wall portion5A viewed from the direction along the axis of peripheral wall portion5A has a shape like a circle partially cut in a straight line. A part of a bolt hole9hdescribed later is formed in peripheral wall portion5A. The center of the circular arc of the outer periphery contour is shifted from the center of motor housing29to the upper side inFIG.4, and coincides with the rotation center of internal gear56described later. Since peripheral wall portion5A is cut, pump housing59can be disposed in first internal space21while ensuring the strength of pump housing59. As a modification of the present embodiment, the center of the arc of the outer periphery contour of peripheral wall portion5A may not coincide with the rotation center of internal gear56. The center of the arc of the outer periphery contour of peripheral wall portion5A may or may not coincide with the rotation center of external gear55.

The inner peripheral contour line of peripheral wall portion5A as viewed from the direction along the axis of peripheral wall portion5A is circular. The inner diameter of peripheral wall portion5A is slightly larger than the outer diameter of internal gear56. Therefore, internal gear56can rotate while the outer peripheral surface of internal gear56is in contact with the inner peripheral surface of peripheral wall portion5A. The rotation axis of internal gear56is stabilized by being supported by the inner peripheral surface of peripheral wall portion5A.

As shown inFIG.5, first cover5B is a plate-shaped member that seals the first end portion of peripheral wall portion5A. First cover5B of the present embodiment is a component independent of peripheral wall portion5A. As a modification of the present embodiment, first cover5B may be a component integrated with peripheral wall portion5A. First cover5B may be a component integrated with first cover2B of motor housing29. In the present embodiment, first cover5B is fitted into a through hole of annular base portion2Bb constituting a part of first cover2B of motor housing29. That is, first cover5B and base portion2Bb into which first cover5B is fitted constitute first cover2B of motor housing29. First cover5B is formed with through holes constituting inlet port51and outlet port52. A recess is formed on the inner surface of first cover5B. An end portion of motor shaft20is rotatably fitted in the recess.

Second cover5C is a plate-shaped member that seals the second end portion of peripheral wall portion5A. Second cover5C of the present embodiment is a component independent of peripheral wall portion5A. As a modification of the present embodiment, second cover5C may be a component integrated with peripheral wall portion5A. The second end portion is an end portion opposite to the first end portion. A recess5D is formed in a surface of second cover5C facing first pump rotor50. The number of recesses5D in the present embodiment is two. Two recesses5D are provided at positions facing each other across motor shaft20. Each recess5D has a substantially arc shape when viewed from the direction along the axis of motor shaft20. Two recesses5D may have different shapes or the same shape. Recess5D reduces the sliding area between external gear55and second cover5C and the sliding area between internal gear56and second cover5C, thereby reducing the torque loss of first pump5. Motor shaft20penetrates second cover5C. A bearing26is disposed between motor shaft20and the through hole through which motor shaft20penetrates. Therefore, motor shaft20is rotably supported by second cover5C. A seal member for suppressing leakage of the fluid from pump housing59may be disposed at the position of bearing26.

As shown inFIG.6, in the present embodiment, peripheral wall portion5A, first cover5B, and second cover5C are integrated by a bolt9. Bolt hole9hin which bolt9is disposed extends from first cover5B to second cover5C through peripheral wall portion5A. As shown inFIG.4, the number of bolt holes9hin the present embodiment is three. Three bolt holes9hare arranged at equal intervals so as to surround internal gear56.

As shown inFIG.6, bolt9connects first cover5B, peripheral wall portion5A, and second cover5C. First cover5B of the present embodiment is integrated with first cover2B of motor housing29. Therefore, first cover5B, peripheral wall portion5A, and second cover5C are connected by bolt9, so that the first end portion of peripheral wall portion2A of motor housing29is sealed by first cover2B.

Bolt hole9hof the present embodiment includes a smaller-diameter portion95in which a shaft90of bolt9is disposed and a larger-diameter portion96in which a head91of bolt9is disposed. A thread groove is formed in at least a portion of smaller-diameter portion95corresponding to second cover5C. A screw groove may be formed in at least a part of a portion of smaller-diameter portion95corresponding to peripheral wall portion5A. Head91is stopped by abutting against a step between smaller-diameter portion95and larger-diameter portion96. Head91is housed in larger-diameter portion96and does not protrude from the end surface of first cover5B. Therefore, head91does not increase the axial dimension of pump assembly1. As shown inFIGS.1and2, a tool hole into which a tool for rotating bolt9is fitted is formed in the end surface of head91. The tool hole of the present embodiment has a hexagonal shape. The shape of the tool hole is not particularly limited.

As shown inFIG.4, external gear55is coaxially fixed to motor shaft20. That is, the rotation axis of external gear55and the rotation axis of motor shaft20coincide with each other. The rotation axis of external gear55also coincides with the axis of motor housing29. External gear55rotates in perfect synchronization with the rotation of motor rotor3. Therefore, the rotational speed of external gear55can be controlled by controlling the rotational speed of motor rotor3. The flow rate of the fluid pumped by first pump5varies depending on the rotational speed of external gear55.

The rotation axis of internal gear56positioned by peripheral wall portion5A of pump housing59is shifted upward in the drawing from the rotation axis of external gear55. Therefore, internal gear56rotates in accordance with the rotation of external gear55, and the gap between external gear55and internal gear56moves in the rotation direction of motor shaft20. Inlet port51and outlet port52are opened in a gap between external gear55and internal gear56. Therefore, the fluid flowing into the gap from inlet port51is carried in the rotational direction of motor shaft20and is discharged to the outside of first pump5from outlet port52.

Inlet port51and outlet port52are arranged at substantially symmetrical positions with motor shaft20interposed therebetween. Inlet port51and outlet port52are disposed in the first direction as viewed from first pump rotor50, that is, external gear55. The first direction is a direction along the axis of motor shaft20and is a direction away from motor rotor3. In the present embodiment, inlet port51and outlet port52are formed in first cover5B disposed in the first direction from first pump rotor50. Inlet port51and outlet port52of the present embodiment extend in the first direction and open on the end surface of first cover5B. As a modification of the present embodiment, inlet port51and outlet port52may be bent in an L shape, for example. In this case, inlet port51and outlet port52may be opened in a direction intersecting the first direction. Since rotating motor rotor3is not present at the positions where inlet port51and outlet port52are arranged, inlet port51and outlet port52can be easily arranged.

As a modification of the present embodiment, inlet port51and outlet port52may extend in the radial direction. The radial direction is a direction orthogonal to the axis of motor shaft20and is a direction away from the axis of motor shaft20. In this case, inlet port51and outlet port52each extend from between two adjacent first teeth41to the outside of pump assembly1.

In pump assembly1of the present embodiment, first pump5is disposed in first internal space21of motor2. That is, the length of pump assembly1of the present embodiment along motor shaft20does not increase even though first pump5is provided. Such compact pump assembly1is easy to arrange in a narrow space such as the interior of an automobile.

First pump5generates an operating noise. The operating noise is, for example, a contact noise between external gear55and internal gear56, and a pulsation noise generated when the fluid is pressure-fed. External gear55and internal gear56, which are sources of operating noise, are surrounded by pump housing59. Moreover, first pump5is disposed inside motor2. Therefore, in pump assembly1of the present embodiment, the operating noise of first pump5is unlikely to leak to the outside of pump assembly1. Pump assembly1of the present embodiment is excellent in quietness.

Motor2generates heat during operation. The temperature of first pump5disposed in first internal space21of motor2is likely to rise due to the heat generation of motor2. When the temperature of first pump5rises, the temperature of the fluid in first pump5rises, and the viscosity of the fluid decreases. As a result, the load of motor2is reduced, and the power consumption of motor2is reduced. In particular, after starting motor2, where the temperature of the fluid is low, the load of motor2can easily be reduced early. First pump5disposed in first internal space21has a high heat capacity due to its structure. Therefore, first pump5easily receives heat generated by motor2, and can suppress heat generation of motor2.

Second Embodiment

First pump5provided in pump assembly1is not limited to an internal gear pump. For example, first pump5may be an external gear pump, an impeller pump, a diaphragm pump, a vane pump, or a piston pump. In the second embodiment, pump assembly1including a vane pump as first pump5will be described with reference toFIG.7. The view ofFIG.7is the same as that ofFIG.4.

The vane pump includes first pump rotor50having a plurality of vanes58. Vane58is configured to be movable forward and backward by, for example, a magnetic force or a centrifugal force. As viewed from the direction along the axis of motor shaft20, the shape of the inner circumferential surface of pump housing59in which first pump rotor50is housed is substantially elliptical. As a modification of the present embodiment, the shape of the inner peripheral surface of pump housing59may be circular. As first pump rotor50rotates, the end portion of vane58comes into contact with the inner circumferential surface of pump housing59, and vane58moves forward or backward. The fluid is arranged in the space surrounded by two adjacent vanes58,58, the inner circumferential surface of pump housing59, and first pump rotor50, and the fluid is carried in the rotation direction of first pump rotor50as first pump rotor50rotates. The vane pump has excellent sealing performance, and therefore can easily pump a gas, a liquid, or a mixture of a gas and a liquid.

Pump assembly1of the present embodiment includes two inlet ports51and two outlet ports52. Inlet ports51and outlet ports52are alternately arranged around the axis of motor shaft20. There may be one inlet port51and one outlet port52.

Third Embodiment

In the third embodiment, pump assembly1including motor2of single-rotor and double-stator type will be described with reference toFIG.8. The view ofFIG.8is similar to that ofFIG.5.

Motor2of the present embodiment further includes a second stator6that sandwiches motor rotor3between first stator4and second stator6. Second stator6has the same configuration as first stator4. That is, second stator6includes a second yoke60having an annular shape, a plurality of second teeth61, and a plurality of second coils62. Second teeth61are disposed on a second surface60sof second yoke60. Second surface60sis a surface facing first surface40sof first yoke40. The end surface of second teeth61has the same shape as the end surface of first teeth41and faces the end surface of first teeth41. That is, first stator4and second stator6are disposed symmetrically with respect to motor rotor3.

Motor rotor3of the present embodiment also has the plurality of magnets31on the surface facing second stator6. As a modification of the present embodiment, magnet31may be embedded in base plate30. In this case, one magnet31corresponds to both first stator4and second stator6.

Motor2of single-rotor and double-stator type is usually more space efficient than motor2of single-rotor and single-stator type.

Motor2has a second internal space22surrounded by a plurality of second teeth61. A second pump7is disposed in second internal space22. That is, first pump5and second pump7are disposed symmetrically with respect to motor rotor3. Second pump7is a pump independent of first pump5. Second pump7has the same configuration as first pump5. That is, second pump7is an internal gear pump having an external gear75and an internal gear76. External gear75is a second pump rotor70configured to be rotated by motor rotor3. Specifically, second pump rotor70is coaxially fixed to motor shaft20. That is, motor shaft20serves as a rotation axis of first pump rotor50and second pump rotor70. External gear75and internal gear76are disposed inside a pump housing79. As a modification of the present embodiment, first pump5and second pump7may be pumps of types other than the internal gear pump. First pump5and second pump7may be pumps of different types. For example, first pump5may be an internal gear pump, and second pump7may be a vane pump.

An inlet port71and an outlet port72extend along the axis of motor shaft20. The opening of inlet port71and the opening of outlet port72are disposed at positions away from motor rotor3. Since rotating motor rotor3is not present at the positions where inlet port71and outlet port72are arranged, inlet port71and outlet port72can be easily arranged.

Peripheral wall portion2A of motor housing29has a size capable of housing both first pump5and second pump7. Therefore, pump assembly1of the present embodiment is compact despite having two pumps.

First cover2B of motor housing29of the present embodiment has the same configuration as first cover2B of the first embodiment. Second cover2C of motor housing29of the present embodiment has the same configuration as first cover2B. Therefore, although a part of pump housing79penetrates second cover2C, pump housing79does not protrude from the end surface of second cover2C. As a modification of the present embodiment, pump housing59may protrude from the end surface of first cover2B, and pump housing79may protrude from the end surface of second cover2C.

Pump assembly1of the present embodiment having the configuration described above can pressure-feed fluids of two independent systems.

Fourth Embodiment

In the fourth embodiment, pump assembly1in which the configurations of motor housing29and pump housing59are different from those in the first embodiment will be described with reference toFIG.9. In the present embodiment, the configuration other than motor housing29and pump housing59is the same as that of the first embodiment.

FIG.9is a cross-sectional view of pump assembly1of the present embodiment taken along a line corresponding to the line VI-VI inFIG.4. The position of bolt9in the present embodiment is different from that in the first embodiment.

Pump housing59of the present embodiment includes a body8and a pump cover8C. Body8is a bottomed cylindrical component including a cylindrical portion80, a bottom portion81, and an annular flange portion82. InFIG.9, the boundary between cylindrical portion80and bottom portion81and the boundary between cylindrical portion80and annular flange portion82are indicated by two dot chain lines.

Cylindrical portion80is a portion that covers the outer periphery of internal gear56. That is, cylindrical portion80corresponds to peripheral wall portion5A of pump housing59in the first embodiment. Bottom portion81is an arranged portion that seals the first end surface of cylindrical portion80and faces motor rotor3. A through hole through which motor shaft20penetrates is formed in bottom portion81. That is, bottom portion81corresponds to second cover5C of pump housing59in the first embodiment. Annular flange portion82is a portion extending toward the outside of cylindrical portion80from the outer peripheral surface of cylindrical portion80at a position near the second end surface. The second end surface is an end surface opposite to the first end surface. The outside of cylindrical portion80is a direction away from the central axis of cylindrical portion80. Annular flange portion82is generally annular in shape. First yoke40of first stator4is fixed to the surface of annular flange portion82facing motor rotor3. That is, annular flange portion82corresponds to base portion2Bb of motor housing29in the first embodiment. Body8in which cylindrical portion80, bottom portion81, and annular flange portion82are integrated is expected to contribute to a reduction in the number of assembly steps of pump assembly1and a reduction in the cost of pump assembly1due to a reduction in the number of components.

Pump cover8C seals an opening80hthat opens to the second end surface of cylindrical portion80. Pump cover8C corresponds to first cover5B of pump housing59in the first embodiment. The outer diameter of pump cover8C is larger than the inner diameter of opening80h. Pump cover8C and annular flange portion82correspond to first cover2B of motor housing29in the first embodiment.

Pump cover8C is fixed to annular flange portion82of body8by bolt9. Bolt hole9hin which bolt9is disposed penetrates pump cover8C and reaches annular flange portion82. That is, when viewed in a direction along shaft90of bolt9, shaft90does not overlap cylindrical portion80of body8, and bolt hole9hfor disposing bolt9is not formed in cylindrical portion80. Cylindrical portion80is thinner than peripheral wall portion5A in the first embodiment by the amount of bolt hole9hnot formed. The outer diameter of cylindrical portion80can be reduced as compared with the configuration of the first embodiment by the amount of the reduction in the thickness of cylindrical portion80. In the configuration of the first embodiment, if the outer diameter of cylindrical portion80is reduced without changing the inner diameter of cylindrical portion80, the outer diameter of pump assembly1can be reduced without reducing the capacity of first pump5. The outer diameter of pump assembly1is a dimension of pump assembly1in a direction orthogonal to the axis of motor shaft20.

The inner diameter of cylindrical portion80may be reduced as compared with the configuration of the first embodiment by the amount of the reduction in the thickness of cylindrical portion80. For example, in the configuration of the first embodiment, if the inner diameter of cylindrical portion80is increased without changing the outer diameter of cylindrical portion80, the capacity of first pump5can be increased without increasing the outer diameter of the pump assembly. In addition, the outer diameter of cylindrical portion80may be reduced and the inner diameter of cylindrical portion80may be increased with respect to the configuration of the first embodiment.

In the configuration of the present embodiment in which bolt9is connected to annular flange portion82, bolt9does not interfere with inlet port51and outlet port52in the first place. Therefore, the number and the position of bolts9in the present embodiment are less restricted than those in the configuration of the first embodiment.

The configurations of motor housing29and pump housing59shown in the fourth embodiment can also be applied to pump assembly1including motor2of single-rotor and double-stator type shown in the third embodiment.

REFERENCE SIGNS LIST