Pump Assembly

Abstract

This pump assembly comprises: an axial gap motor having a stator, a motor rotor, and a motor shaft; and a pump having a pump rotor that is configured to be rotated by the motor rotor and a pump housing that houses the pump rotor. The stator is provided with an annular yoke, and a plurality of teeth arranged on a first surface of the yoke. The pump is disposed in an internal space surrounded by the teeth. The pump housing is provided with a flow passage space formed inside the pump housing, and a leakage flow passage that opens from the flow passage space toward the motor rotor.

Description

Technical Field

[0001] The present disclosure relates to a pump assembly. This application claims priority based on Japanese Patent Application No. 2022-202208 filed on December 19, 2022, and incorporates by reference all the descriptions set forth in the Japanese application.

Background Art

[0002] An axial gap motor has a stator, a motor rotor, and a motor shaft. In an axial gap motor, the magnetic flux flowing from the stator toward the rotor is parallel to the axis of the motor shaft. The axial gap motor has the advantage of a small length along the axis.

[0003] Patent Document 1 discloses a pump assembly that combines an axial gap motor and an electric pump for pumping 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 the motor shaft. Such a pump assembly that takes advantage of the axial gap motor with a small size along the axis is compact. In a pump assembly using a radial gap motor, the size along the axis of the motor shaft is large.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] The pump assembly of the present disclosure includes an axial-gap motor having a stator, a motor rotor, and a motor shaft, a pump rotor configured to be rotated by the motor rotor, and a pump having a pump housing that houses the pump rotor. The stator includes an annular yoke and a plurality of teeth disposed on a first surface of the yoke. The pump is disposed in an internal space surrounded by the plurality of teeth. The pump housing includes a flow path space formed inside the pump housing and a leak flow path that opens from the flow path space toward the motor rotor.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0007] [Problems to be Solved by the Present Disclosure] The pump assembly is used, for example, to supply oil to the drive mechanism of an automobile. In this case, the pump assembly is arranged in a limited and narrow space such as an automobile engine room. Therefore, even when an axial gap motor is used, there is a greater demand for a pump assembly with a more compact length along the axis.

[0008] The axial gap motor generates heat during operation and there is a risk of performance degradation. If a cooling mechanism for cooling the axial gap motor is separately added to the pump assembly, there is a problem that the pump assembly becomes larger in size.

[0009] One of the objectives of the present disclosure is to provide a compact pump assembly that is less likely to have problems due to heat generation.

[0010] [Effects of the Present Disclosure] The pump assembly of the present disclosure is less likely to have problems due to heat generation and is more compact than conventional pump assemblies.

[0011] [Description of Embodiments of the Present Disclosure] First, the embodiments of the present disclosure will be listed and described.

[0012] <1>The pump assembly of the present disclosure includes an axial gap motor having a stator, a motor rotor, and a motor shaft, a pump rotor configured to be rotated by the motor rotor, and a pump having a pump housing that houses the pump rotor. The stator includes an annular yoke and a plurality of teeth disposed on a first surface of the yoke. The pump is disposed in an internal space surrounded by the plurality of teeth. The pump housing includes a flow path space formed inside the pump housing and a leak flow path that opens from the flow path space toward the motor rotor.

[0013] In the pump assembly described in <1> above, the pump is disposed in the internal space of the axial gap motor surrounded by a plurality of first teeth. Therefore, the length along the axis of the motor shaft in the pump assembly described in <1> above is smaller than the length along the axis of the motor shaft in a conventional pump assembly. The pump rotor rotated by the motor rotor may be coaxially fixed to the motor shaft.

[0014] In the pump assembly described in <1> above, a part of the fluid flowing through the flow path space of the pump housing leaks to the motor rotor through the leakage flow path. The leaked fluid spreads over the entire surface of the motor rotor by the centrifugal force of the motor rotor, or scatters inside the axial gap motor and adheres to the stator. At this time, the fluid takes away the heat of the motor rotor and the stator and cools the axial gap motor. Therefore, the pump assembly described in <1> above can suppress the problems associated with the heat generation of the axial gap motor while having a simple configuration without an additional cooling mechanism. The fluid in the present disclosure may be a liquid, a gas, or a mixture of a liquid and a gas.

[0015] In the pump assembly described in <1> above, the pump is disposed in the internal space. That is, the pump is disposed inside the axial gap motor and surrounded by the components of the axial gap motor. Therefore, the operating sound of the pump is difficult to leak outside the pump assembly. Therefore, the pump assembly described in <1> above is excellent in quietness.

[0016] In the pump assembly described in <1> above, due to the heat generation of the axial gap motor, the temperature of the pump disposed in the internal space of the axial gap motor tends to rise. When the temperature of the pump rises, the temperature of the fluid in the pump rises, and the viscosity of the fluid decreases. As a result, the load on the axial gap motor is reduced, and the power consumption of the axial gap motor decreases. In particular, after starting the axial gap motor with a low fluid temperature, the load on the axial gap motor tends to be reduced early. The pump disposed in the internal space has a high heat capacity due to its structure. Therefore, the pump easily receives the heat generated by the axial gap motor and can suppress the heat generation of the axial gap motor.

[0017] <2>In the pump assembly described in <1> above, the pump housing has a through hole connecting the inside and the outside of the pump housing, and a part of the motor shaft is disposed inside the pump housing through the through hole, and the leak flow path may be constituted by a gap between the through hole and the motor shaft.

[0018] The gap between the through hole of the pump housing and the motor shaft is very narrow. By using this gap as a leak flow path, it is possible to suppress excessive leakage of fluid from the pump. Therefore, the axial gap motor can be cooled without impairing the fluid pumping ability of the pump.

[0019] <3>In the pump assembly described in <1> or <2> above, the pump includes an inlet port and an outlet port, and the inlet port and the outlet port may be arranged in a first direction when viewed from the pump rotor. The first direction is a direction along the axis of the motor shaft and away from the motor rotor.

[0020] Since there is no motor rotor in the first direction when viewed from the pump rotor, the arrangement of the inlet port and the outlet port is easy. Further, since the inlet port and the outlet port are arranged in the first direction, the increase in the outer diameter of the stator core is suppressed.

[0021] Unlike the configuration described in <3> above, when the inlet port and the outlet port are arranged in the radial direction, the inlet port and the outlet port are arranged in the gaps between a plurality of teeth aligned with the annular yoke. The radial direction is a direction orthogonal to the axis of the motor shaft and away from the axis. The inlet port and the outlet port along the radial direction tend to increase the outer diameter of the stator core in order to increase the interval between the plurality of teeth.

[0022] <4>In the pump assembly according to any one of <1> to <3> above, the axial gap motor includes a motor housing, and the motor housing may include a drain passage connecting the inside and the outside of the motor housing.

[0023] When the viscosity of the fluid is high, it becomes difficult for the motor rotor to rotate due to the fluid accumulated inside the axial gap motor. The drain passage discharges the fluid inside the axial gap motor to the outside. Therefore, in the pump assembly described in <4> above, it is possible to prevent the problems caused by the accumulation of fluid inside the axial gap motor.

[0024] <5>In the pump assembly according to any one of <1> to <4> above, the pump is an internal gear pump including an external gear and an internal gear, and the external gear may be the pump rotor.

[0025] An internal gear pump with an external gear arranged inside an internal gear is compact. This internal gear pump is easy to arrange in an internal space with size constraints. Also, the internal gear pump has good space efficiency compared to other pumps of the same size. Therefore, the pump assembly described in <5> above is compact and easy to increase the fluid flow rate.

[0026] <6>In the pump assembly according to any one of <1> to <4> above, the pump is a vane pump, and the pump rotor may have a plurality of vanes.

[0027] A vane pump having a pump rotor with a plurality of vanes is compact. This vane pump is easy to arrange in an internal space with size constraints. Also, since the vane pump has excellent sealing performance, it can be easily pumped even if it is a gas, a liquid, or a mixture of gas and liquid.

[0028] <7>In the pump assembly according to <3> above, the pump housing may be provided with a return flow path connecting the internal space and the inlet port.

[0029] With the above return flow path, the fluid that has leaked into the internal space of the axial gap motor can be returned to the flow path space of the pump. Therefore, the fluid that cools the axial gap motor is not wasted.

[0030] [Details of Embodiments of the Present Disclosure] Hereinafter, a specific example of the pump assembly of the present disclosure will be described with reference to the drawings. The same reference numerals in the drawings indicate the same or corresponding parts. The sizes of the members shown in each drawing are expressed for the purpose of clarifying the description and do not necessarily represent the actual dimensions. Note that the present invention is not limited to these examples, and is intended to be indicated by the claims and to include all modifications within the meaning and scope equivalent to the claims.

[0031] <Embodiment 1> The pump assembly 1 shown in FIGS. 1 and 2 includes an axial gap motor 2 and a first pump 5. From the outside of the pump assembly 1, the motor housing 29 of the axial gap motor 2 and the pump housing 59 of the first pump 5 are visible. An inlet port 51 and an outlet port 52 are open in the pump housing 59. As shown in the plan view of FIG. 2, behind the inlet port 51 and the outlet port 52, an external gear 55 and an internal gear 56 provided in the first pump 5, which will be described later, are visible. Hereinafter, each component of the pump assembly 1 will be described. In the following description, the "axial gap motor" will be simply referred to as the "motor".

[0032] <<Motor>> In the description of the motor 2, mainly refer to FIG. 3, which is an exploded perspective view of the motor 2, and refer to FIG. 5, which is a cross-sectional view of the pump assembly 1 as necessary. The motor 2 includes a first stator 4, a motor rotor 3, and a motor shaft 20. As shown in FIG. 5, the first stator 4 and the motor rotor 3 are arranged coaxially with the motor shaft 20. The first stator 4 and the motor rotor 3 face each other with a gap in the direction along the axis of the motor shaft 20. The motor 2 in this example is a single rotor - single stator type motor including one first stator 4 and one motor rotor 3.

[0033] The first stator 4 includes a first yoke 40, a plurality of first teeth 41, and a plurality of first coils 42. The first yoke 40 is a plate material configured in an annular shape. The first teeth 41 are columnar bodies. The first teeth 41 protrude from the planar first surface 40s of the first yoke 40. The shapes and sizes of the plurality of first teeth 41 are the same. The shape of each first tooth 41 is, for example, prismatic or cylindrical. The first stator 4 in this example is, for example, composed of an integral compacted body. Different from this example, the first stator 4 may be composed of a plurality of divided pieces.

[0034] The end face of the first tooth 41 faces the magnet 31 of the motor rotor 3 described later. A first coil 42 is disposed on the outer peripheral surface of the first tooth 41. When an electric current flows through the first coil 42, the first stator 4 is excited and a rotating magnetic field is generated. In this example, illustration of the end portions of the windings constituting the first coil 42 is omitted.

[0035] The motor rotor 3 includes a base plate 30 and a plurality of magnets 31. The base plate 30 is an annular plate material through which the motor shaft 20 passes. The base plate 30 and the motor shaft 20 are fixed, and the base plate 30 and the motor shaft 20 rotate coaxially. The base plate 30 includes a base surface 30s facing the first surface 40s of the first yoke 40.

[0036] The plurality of magnets 31 are fixed to the base surface 30s by, for example, an adhesive. The magnets 31 are permanent magnets. The plurality of magnets 31 are arranged at substantially equal intervals around the axis of the motor shaft 20. The shape of the magnet 31 is, for example, a flat plate shape. The planar shape of the magnet 31 is, for example, a shape corresponding to the shape of the end face of the first tooth 41. The magnet 31 is magnetized in the direction along the axis of the motor shaft 20. The magnetization directions of two adjacent magnets 31 around the axis of the motor shaft 20 are opposite to each other. Due to the rotating magnetic field generated in the first stator 4, the magnet 31 is attracted or repelled by the first tooth 41, so that the motor rotor 3 rotates with respect to the first stator 4.

[0037] As shown in FIG. 5, the motor 2 further includes a motor housing 29. The above-described first stator 4 and motor rotor 3 are disposed inside the motor housing 29. Also, a part of the motor shaft 20 is disposed inside the motor housing 29. Different from this example, the entire motor shaft 20 may be disposed inside the motor housing 29.

[0038] The motor housing 29 in this example is composed of a peripheral wall portion 2A, a first cover 2B, and a second cover 2C. The peripheral wall portion 2A and the second cover 2C may be integral parts. The peripheral wall portion 2A is a cylindrical member. The inner diameter of the peripheral wall portion 2A is larger than the outer diameter of the first stator 4. The length of the peripheral wall portion 2A along the axial direction of the motor shaft 20 is larger than the length of the first stator 4 along the motor shaft 20.

[0039] The first cover 2B is an annular member that seals the first end portion of the peripheral wall portion 2A. The first end portion is the end portion close to the first yoke 40 of the first stator 4. The first yoke 40 is fixed to the first cover 2B. A part of the pump housing 59 described later penetrates through the first cover 2B. A flange is provided on the outer peripheral edge of the first cover 2B. The protruding height of the pump housing 59 is the same as or lower than the end face of the flange. Therefore, the protruding portion of the pump housing 59 is accommodated in a concave space formed inside the flange of the first cover 2B.

[0040] The second cover 2C is an annular member that seals the second end portion of the peripheral wall portion 2A. The second end portion is the end portion on the opposite side of the first end portion. The second cover 2C may be a member independent of the peripheral wall portion 2A or may be integrated with the peripheral wall portion 2A. The motor shaft 20 penetrates through the second cover 2C. A bearing 25 is disposed between the second cover 2C and the motor shaft 20, and the motor shaft 20 is rotatably supported with respect to the second cover 2C. A seal member for suppressing leakage of fluid from inside the motor housing 29 may be disposed at the position of the bearing 25. Different from this example, when the entire motor shaft 20 is disposed inside the motor housing 29, the inner surface of the second cover 2C is provided with a concave portion into which the end portion of the motor shaft 20 is fitted.

[0041] <<First Pump>> In the description of the first pump 5, mainly refer to FIGS. 4 and 5. FIG. 4 is a diagram for explaining the arrangement state of the first pump 5 in the pump assembly 1, and some members of the pump assembly 1 are omitted or simplified. For example, in FIG. 4, the first cover 2B of the motor housing 29 and the motor rotor 3 are omitted. Also, in FIG. 4, the first cover 5B (FIG. 5) of the pump housing 59 described later is omitted, and a state where the inside of the first pump 5 is exposed is shown. In this FIG. 4, the first stator 4, the inlet port 51 and the outlet port 52 are indicated by a two-dot chain line.

[0042] The first pump 5 pumps fluid. The fluid in this example is a liquid. For example, the fluid is machine oil. The first pump 5 includes a first pump rotor 50 configured to be rotated by the motor rotor 3. This first pump 5 is disposed in a first internal space 21 surrounded by a plurality of first teeth 41.

[0043] The first pump 5 in this example is an internal gear pump having an external gear 55 and an internal gear 56. The external gear 55 is a disk-shaped gear having teeth on its outer circumference. The tooth profile of the external gear 55 is constituted by, for example, a trochoid curve. The internal gear 56 is an annular gear having teeth on its inner circumference. The external gear 55 is disposed inside the internal gear 56, and the teeth of the external gear 55 and the teeth of the internal gear 56 mesh with each other. In this internal gear pump, the external gear 55 is the first pump rotor 50.

[0044] The external gear 55 and the internal gear 56 are disposed inside the pump housing 59. As shown in FIG. 5, the pump housing 59 in this example is composed of a peripheral wall portion 5A, a first cover 5B, and a second cover 5C. Inside the pump housing 59 surrounded by the peripheral wall portion 5A, the first cover 5B, and the second cover 5C, a flow path space 5S through which fluid flows is formed. The flow path space 5S also includes the gap between the external gear 55 and the internal gear 56.

[0045] The peripheral wall portion 5A is a cylindrical member. As shown in FIG. 4, the outer peripheral contour line of the peripheral wall portion 5A viewed from the direction along the axis of the peripheral wall portion 5A has a shape in which a part of a circle is linearly cut. The center of the arc of the outer peripheral contour line is shifted upward in FIG. 4 from the center of the motor housing 29 and coincides with the rotation center of the internal gear 56 described later. Since the peripheral wall portion 5A is cut, the pump housing 59 can be disposed in the first internal space 21 while ensuring the strength of the pump housing 59. Different from this example, the center of the arc of the outer peripheral contour line of the peripheral wall portion 5A does not have to coincide with the rotation center of the internal gear 56. Further, the center of the arc of the outer peripheral contour line of the peripheral wall portion 5A may or may not coincide with the rotation center of the external gear 55.

[0046] The inner peripheral contour line of the peripheral wall portion 5A viewed from the direction along the axis of the peripheral wall portion 5A is circular. The inner diameter of the peripheral wall portion 5A is slightly larger than the outer diameter of the internal gear 56. Therefore, the internal gear 56 can rotate while the outer peripheral surface of the internal gear 56 contacts the inner peripheral surface of the peripheral wall portion 5A. The rotation axis of the internal gear 56 is stabilized by being supported by the inner peripheral surface of the peripheral wall portion 5A.

[0047] As shown in FIG. 5, the first cover 5B is a plate-like member that seals the first end portion of the peripheral wall portion 5A. The first cover 5B may be a component integral with the first cover 2B of the motor housing 29. Further, the first cover 5B may be a component integral with the peripheral wall portion 5A. The first end portion is an end portion close to the first yoke 40. Through holes constituting the inlet port 51 and the outlet port 52 are formed in the first cover 5B. A recess is formed on the inner surface of the first cover 5B. The end portion of the motor shaft 20 is rotatably fitted into the recess.

[0048] The second cover 5C is a plate-like member that seals the second end of the peripheral wall portion 5A. The second cover 5C may be an integral part with the peripheral wall portion 5A. The second end is the end on the side opposite to the first end. A recess 5D is formed on the surface of the second cover 5C facing the first pump rotor 50. The number of recesses 5D in this example is two. The two recesses 5D are provided at positions facing each other with the motor shaft 20 interposed therebetween. The shape of each recess 5D as viewed from the direction along the axis of the motor shaft 20 is generally arc-shaped. The shapes of the two recesses 5D may be different or the same. The recesses 5D reduce the sliding areas between the external gear 55 and the second cover 5C, and between the internal gear 56 and the second cover 5C, and reduce the torque loss of the first pump 5. The second cover 5C includes a through-hole 5h that penetrates the motor shaft 20. A bearing 26 is disposed between the through-hole 5h and the motor shaft 20. Therefore, the motor shaft 20 is rotatably supported with respect to the second cover 5C. The gap between the through-hole 5h and the motor shaft 20 is very narrow. In this example, this gap is used as a leakage flow path 8. Details of the leakage flow path 8 will be described later.

[0049] As shown in FIG. 4, the external gear 55 is coaxially fixed to the motor shaft 20. That is, the rotation axis of the external gear 55 coincides with the rotation axis of the motor shaft 20. The rotation axis of the external gear 55 also coincides with the axis of the motor housing 29. The external gear 55 rotates completely synchronously with the rotation of the motor rotor 3. Therefore, the rotation speed of the external gear 55 can be controlled by controlling the rotation speed of the motor rotor 3. The flow rate of the fluid pumped by the first pump 5 changes according to the rotation speed of the external gear 55.

[0050] The rotation axis of the internal gear 56 positioned by the peripheral wall portion 5A of the pump housing 59 is displaced above the rotation axis of the external gear 55 in the drawing. Therefore, as the external gear 55 rotates, the internal gear 56 rotates, and the gap between the external gear 55 and the internal gear 56 moves in the rotation direction of the motor shaft 20. The inlet port 51 and the outlet port 52 are open to the gap between the external gear 55 and the internal gear 56. Therefore, the fluid flowing into the gap from the inlet port 51 is carried in the rotation direction of the motor shaft 20 and discharged to the outside of the first pump 5 from the outlet port 52.

[0051] The inlet port 51 and the outlet port 52 are arranged at positions that are generally symmetric with respect to the motor shaft 20. The inlet port 51 and the outlet port 52 are arranged in a first direction when viewed from the first pump rotor 50, that is, the external gear 55. The first direction is the direction along the axis of the motor shaft 20 and away from the motor rotor 3. In this example, the inlet port 51 and the outlet port 52 are formed in the first cover 5B arranged in the first direction with respect to the first pump rotor 50. The inlet port 51 and the outlet port 52 of this example extend in the first direction and open to the end face of the first cover 5B. Different from this example, the inlet port 51 and the outlet port 52 may be bent, for example, in an L shape. In that case, the inlet port 51 and the outlet port 52 may open in a direction intersecting the first direction. Since there is no rotating motor rotor 3 at the positions where the inlet port 51 and the outlet port 52 are arranged, the arrangement of the inlet port 51 and the outlet port 52 is easy.

[0052] Different from this example, the inlet port 51 and the outlet port 52 may extend in the radial direction. The radial direction is the direction perpendicular to the axis of the motor shaft 20 and away from the axis of the motor shaft 20. In this case, the inlet port 51 and the outlet port 52 each extend from the outside of the pump assembly 1 between two adjacent first teeth 41.

[0053] In the pump assembly 1 of this example, the first pump 5 is disposed in the first internal space 21 of the motor 2. That is, the length along the motor shaft 20 in the pump assembly 1 of this example does not increase even though the first pump 5 is provided. Such a compact pump assembly 1 is easy to be disposed in a narrow space such as inside an automobile.

[0054] The first pump 5 generates an operating sound. The operating sound is, for example, the contact sound between the external gear 55 and the internal gear 56, and the pulsation sound generated when the fluid is pumped. The external gear 55 and the internal gear 56, which are the sources of the operating sound, are surrounded by the pump housing 59. Moreover, the first pump 5 is disposed inside the motor 2. Therefore, in the pump assembly 1 of this example, the operating sound of the first pump 5 hardly leaks to the outside of the pump assembly 1. Such a pump assembly 1 of this example is excellent in quietness.

[0055] The motor 2 generates heat during operation. Due to the heat generation of the motor 2, the temperature of the first pump 5 disposed in the first internal space 21 of the motor 2 is likely to rise. When the temperature of the first pump 5 rises, the temperature of the fluid in the first pump 5 rises, and the viscosity of the fluid decreases. As a result, the load on the motor 2 is reduced, and the power consumption of the motor 2 decreases. In particular, after the start of the motor 2 with a low fluid temperature, the load on the motor 2 is likely to be reduced early. The first pump 5 disposed in the first internal space 21 has a high heat capacity in terms of structure. Therefore, the first pump 5 is likely to receive the heat generated by the motor 2 and can suppress the heat generation of the motor 2.

[0056] <<Leakage flow path>> The pump assembly 1 includes a leakage flow path 8. The leakage flow path 8 is for intentionally leaking a part of the fluid flowing through the flow path space 5S into the motor housing 29.

[0057] As described above, the leakage flow path 8 in this example is formed by the gap between the through hole 5h in the pump housing 59 and the motor shaft 20. The through hole 5h opens from the flow path space 5S toward the motor rotor 3. Therefore, the leakage flow path 8 also opens from the flow path space 5S toward the motor rotor 3. Since this leakage flow path 8 is very narrow, excessive fluid does not leak from the flow path space 5S, and the pumping ability of the first pump 5 is not impaired. Different from this example, the leakage flow path 8 may be a through hole that penetrates the second cover 5C in the direction along the thickness. Also in this case, the leakage flow path 8 opens toward the motor rotor 3. The inner diameter of this leakage flow path 8 is set to a size such that the pressure of the fluid in the flow path space 5S does not drop too much.

[0058] In FIG. 5, an example of the movement path of the fluid that has leaked into the motor housing 29 through the leakage flow path 8 is indicated by a thick solid arrow. The fluid in the flow path space 5S leaks through the leakage flow path 8 to the motor rotor 3. In this example, the bearing 26 is arranged at the position of the leakage flow path 8. Therefore, specifically, the fluid leaks to the motor rotor 3 through the gap between the motor shaft 20 and the bearing 26 and the gap inside the bearing 26.

[0059] The fluid leaked from the leakage flow path 8 adheres to the base plate 30 of the motor rotor 3. Here, in FIG. 5, only the side surface of the magnet 31 on the back side of the paper from the cross section of the base plate 30 is visible, and as shown in FIG. 3, the magnet 31 is not arranged at the central portion of the base plate 30. Therefore, the fluid leaked from the leakage flow path 8 adheres to the base surface 30s of the base plate 30, not to the magnet 31. The fluid adhering to the base surface 30s moves in a direction away from the rotation axis of the motor rotor 3 by the centrifugal force of the motor rotor 3. A part of the moving fluid scatters into the first internal space 21 and adheres to the first stator 4. The dispersed fluid in the motor housing 29 takes heat from the components of the motor 2 and cools the motor 2. Therefore, although the pump assembly 1 in this example does not have an additional cooling mechanism, problems associated with heat generation are unlikely to occur.

[0060] <<Drain Flow Path>> The pump assembly 1 of this example further includes a drain passage 80 that connects the inside and the outside of the motor housing 29. In this example, the drain passage 80 is provided in the first cover 5B. The drain passage 80 is for discharging the fluid in the motor housing 29 to the outside. When the viscosity of the fluid is high, it becomes difficult for the motor rotor 3 to rotate due to the fluid accumulated inside the motor 2. The drain passage 80 prevents the rotation of the motor rotor 3 by the fluid from being suppressed by discharging the fluid in the motor housing 29 to the outside.

[0061] The opening of the drain passage 80 facing the outside is directed vertically downward. Therefore, the fluid is quickly discharged from the drain passage 80 by gravity.

[0062] Unlike this example, the drain passage 80 may be provided in the peripheral wall portion 2A. The drain passage 80 provided in the peripheral wall portion 2A extends in a direction intersecting with the motor shaft 20, for example, in a perpendicular direction. In this case, the fluid can be stored in the motor housing 29 up to the height of the drain passage 80, and the motor 2 is easily cooled. Of course, the pump assembly 1 may be arranged such that the motor shaft 20 is along the horizontal direction, the opening of the drain passage 80 is directed vertically downward, and the fluid is actively discharged from the motor housing 29.

[0063] <<Return Passage>> The pump assembly 1 may include a return passage 9 indicated by a two-dot chain line. The return passage 9 connects the first internal space 21 and the inlet port 51. The return passage 9 can return the fluid leaked into the motor housing 29 to the flow path space 5S of the first pump 5. The return passage 9 illustrated in FIG. 5 is provided in the pump housing 59. Specifically, the return passage 9 is provided in the first cover 5B.

[0064] <Embodiment 2> The first pump 5 provided in the pump assembly 1 is not limited to an internal gear pump. For example, the first pump 5 may be an external gear pump, an impeller pump, a diaphragm pump, a vane pump, or a piston pump. In Embodiment 2, a pump assembly 1 including a vane pump as the first pump 5 will be described with reference to FIG. 6. The viewing direction of FIG. 6 is the same as that of FIG. 4.

[0065] The vane pump includes a first pump rotor 50 having a plurality of vanes 58. The vanes 58 are configured to be movable forward and backward by, for example, magnetic force or centrifugal force. When viewed from the direction along the axis of the motor shaft 20, the shape of the inner peripheral surface of the pump housing 59 in which the first pump rotor 50 is accommodated is substantially elliptical. Different from this example, the shape of the inner peripheral surface of the pump housing 59 may be circular. As the first pump rotor 50 rotates, the ends of the vanes 58 contact the inner peripheral surface of the pump housing 59, and the vanes 58 advance or retract. The fluid disposed in the space surrounded by two adjacent vanes 58, 58, the inner peripheral surface of the pump housing 59, and the first pump rotor 50 is carried in the rotation direction of the first pump rotor 50 as the first pump rotor 50 rotates. Since the vane pump has excellent sealing performance, it can easily pump a gas, a liquid, or a mixture of a gas and a liquid.

[0066] The pump assembly 1 of this example includes two inlet ports 51 and two outlet ports 52. The inlet ports 51 and the outlet ports 52 are arranged alternately around the axis of the motor shaft 20. There may be one inlet port 51 and one outlet port 52 each.

[0067] <Embodiment 3> In Embodiment 3, a pump assembly 1 including a single rotor - double stator type motor 2 will be described with reference to FIG. 7. The viewing direction of FIG. 7 is the same as that of FIG. 5. In FIG. 7, the details of the leak flow path 8 and the illustration of the fluid movement path are omitted.

[0068] The motor 2 of this example further includes a second stator 6 that sandwiches the motor rotor 3 between it and the first stator 4. The configuration of the second stator 6 is the same as that of the first stator 4. That is, the second stator 6 includes an annular second yoke 60, a plurality of second teeth 61, and a plurality of second coils 62. The second teeth 61 are disposed on the second surface 60s of the second yoke 60. The second surface 60s is the surface facing the first surface 40s of the first yoke 40. The end faces of the second teeth 61 have the same shape as the end faces of the first teeth 41 and face the end faces of the first teeth 41. That is, with respect to the motor rotor 3, the first stator 4 and the second stator 6 are symmetrically arranged.

[0069] The motor rotor 3 of this example also has a plurality of magnets 31 on the surface facing the second stator 6. Different from this example, the magnets 31 may be embedded in the base plate 30. In that case, one magnet 31 corresponds to both the first stator 4 and the second stator 6.

[0070] A single-rotor double-stator type motor 2 is generally more space-efficient than a single-rotor single-stator type motor 2.

[0071] The motor 2 has a second internal space 22 surrounded by a plurality of second teeth 61. A second pump 7 is disposed in the second internal space 22. That is, the first pump 5 and the second pump 7 are symmetrically arranged with respect to the motor rotor 3. The second pump 7 is a pump independent of the first pump 5. The second pump 7 has the same configuration as the first pump 5. That is, the second pump 7 is an internal gear pump having an external gear 75 and an internal gear 76. The external gear 75 is a second pump rotor 70 configured to be rotated by the motor rotor 3. Specifically, the second pump rotor 70 is coaxially fixed to the motor shaft 20. That is, the motor shaft 20 also serves as the rotation axes of the first pump rotor 50 and the second pump rotor 70. The external gear 75 and the internal gear 76 are disposed inside the pump housing 79. Different from this example, the first pump 5 and the second pump 7 may be pumps of a method other than the internal gear pump. Also, the first pump 5 and the second pump 7 may be pumps of different methods. For example, the first pump 5 may be an internal gear pump and the second pump 7 may be a vane pump.

[0072] The inlet port 71 and the outlet port 72 extend along the axis of the motor shaft 20. The opening of the inlet port 71 and the opening of the outlet port 72 are disposed at positions away from the motor rotor 3. Since there is no rotating motor rotor 3 at the positions where the inlet port 71 and the outlet port 72 are disposed, the arrangement of the inlet port 71 and the outlet port 72 is easy.

[0073] The peripheral wall portion 2A of the motor housing 29 has a size capable of accommodating both the first pump 5 and the second pump 7. Therefore, although the pump assembly 1 of this example includes two pumps, it is compact.

[0074] In this example, a drain passage 80 is provided in the peripheral wall portion 2A. By arranging the pump assembly 1 so that the drain passage 80 faces vertically downward, the fluid in the motor housing 29 can be easily discharged to the outside.

[0075] The first cover 2B of the motor housing 29 in this example has the same configuration as the first cover 2B in Embodiment 1. The second cover 2C of the motor housing 29 in this example has the same configuration as the first cover 2B. Therefore, a part of the pump housing 79 penetrates through the second cover 2C, but the pump housing 79 does not protrude from the end face of the second cover 2C. Different from this example, the pump housing 59 may protrude from the end face of the first cover 2B, or the pump housing 79 may protrude from the end face of the second cover 2C.

[0076] The pump assembly 1 in this example having the configuration described above can pump two independent systems of fluid.

Explanation of Reference Numerals

[0077] 1 Pump assembly 2 Axial gap motor, motor 20 Motor shaft 21 First internal space 22 Second internal space 25, 26 Bearings 29 Motor housing 2A Peripheral wall portion 2B First cover 2C Second cover 3 Motor rotor 30 Base plate 30s Base surface 31 Magnet 4 First stator 40 First yoke 40s First surface 41 First teeth 42 First coil 5 First pump 5h Through hole, 5S Flow path space 50 First pump rotor 51 Inlet port 52 Outlet port 55 External gear 56 Internal gear 58 Vane 59 Pump housing 5A Peripheral wall part 5B First cover 5C Second cover 5D Recessed part 6 Second stator 60 Second yoke 60s Second surface 61 Second teeth 62 Second coil 7 Second pump 70 Second pump rotor 71 Inlet port 72 Outlet port 75 External gear 76 Internal gear 79 Pump housing 8 Leakage flow path 80 Drain flow path 9 Return flow path

Claims

1. An axial gap motor having a stator, a motor rotor, and a motor shaft, and a pump having a pump rotor configured to be rotated by the motor rotor and a pump housing housing the pump rotor, wherein the stator comprises an annular yoke and a plurality of teeth disposed on a first surface of the yoke, the pump rotor is disposed in an internal space surrounded by the plurality of teeth, the pump housing comprises a flow path space formed inside the pump housing and a leak flow path opening from the flow path space toward the motor rotor, a pump assembly.

2. The pump housing has a through hole connecting the inside and the outside of the pump housing, a part of the motor shaft is disposed inside the pump housing through the through hole, and the leak flow path is formed by a gap between the through hole and the motor shaft. The pump assembly according to claim 1.

3. The pump comprises an inlet port and an outlet port, the inlet port and the outlet port are disposed in a first direction as viewed from the pump rotor, and the first direction is a direction along the axis of the motor shaft and away from the motor rotor. The pump assembly according to claim 1 or claim 2.

4. The axial gap motor comprises a motor housing, and the motor housing comprises a drain flow path connecting the inside and the outside of the motor housing. The pump assembly according to claim 1 or claim 2.

5. The pump is an internal gear pump having an external gear and an internal gear, and the external gear is the pump rotor. The pump assembly according to claim 1 or claim 2.

6. The pump is a vane pump, and the pump rotor has a plurality of vanes. The pump assembly according to claim 1 or claim 2.

7. The pump housing comprises a return flow path connecting the internal space and the inlet port. The pump assembly according to claim 3.

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