Electric pump

Abstract

To provide an electric pump which enables improvement of cooling efficiency of a motor part.SOLUTION: One embodiment of an electric pump of the invention includes: a motor part having a shaft rotatable around a center axis; a pump part which is connected to one end in an axial direction of the shaft and driven by power of the motor part to pump a fluid; and a housing which houses the motor part and the pump part. The housing is provided with: a motor chamber in which the motor part is disposed; a pump chamber in which the pump part is disposed; a supply path for causing the fluid to flow from the pump chamber to the motor chamber; and a return path for returning the fluid from the motor chamber to the pump chamber. The shaft has a hollow part which is open in the motor chamber at a first opening and is open in the pump chamber at a second opening. The pump part has: a suction port for suctioning the fluid from the outside; and a discharge port for discharging the fluid to the outside. The housing has a passage part connecting the second opening with the suction port. The return path is provided at the hollow part and the passage part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electric pump. [Background technology]

[0002] In the past, electric pumps equipped with a pump unit and a motor that rotates the pump unit have had problems with temperature rise in the motor. Patent Document 1 discloses an electric pump that returns fluid supplied to the motor to the pump unit through a hollow portion of the shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-539958 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional electric pumps, the hollow part of the hollow shaft is connected to the discharge port of the pump unit. The fluid pressure increases at the discharge port. For this reason, the conventional structure makes it difficult for the fluid to return to the pump unit, making it difficult for the fluid to circulate smoothly.

[0005] In view of the above circumstances, one aspect of the present invention has an object to provide an electric pump that can improve the cooling efficiency of a motor portion. [Means for solving the problem]

[0006] One embodiment of the electric pump of the present invention includes a motor unit having a shaft rotatable about a central axis, a pump unit connected to one axial end of the shaft and driven by the power of the motor unit to pump a fluid, and a housing that accommodates the motor unit and the pump unit. The housing is provided with a motor chamber in which the motor unit is disposed, a pump chamber in which the pump unit is disposed, a supply path for allowing the fluid to flow from the pump chamber to the motor chamber, and a return path for returning the fluid from the motor chamber to the pump chamber. The shaft has a hollow portion that opens into the motor chamber at a first opening and into the pump chamber at a second opening. The pump unit has an inlet that draws the fluid from the outside and an outlet that discharges the fluid to the outside. The housing has a flow path that connects the second opening to the inlet. The return path is provided in the hollow portion and the flow path. [Effects of the Invention]

[0007] According to one aspect of the present invention, it is possible to provide an electric pump that can improve the cooling efficiency of the motor portion. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of an electric pump according to an embodiment. [Figure 2] FIG. 2 is a front view of a first opposing surface of the bottom wall portion of the embodiment. [Figure 3] FIG. 3 is a front view of a second opposing surface (inner surface) of a pump cover according to one embodiment. [Figure 4] FIG. 4 is a partial cross-sectional view of an electric pump according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the following description, figures show an XYZ coordinate system. The Y axis indicates the direction in which a central axis J in the embodiment described below extends. The central axis J shown in each figure is a virtual axis. In the following description, the direction in which the central axis J extends, i.e., the direction parallel to the Y axis, is referred to as the "axial direction." The side of the axial direction Y toward which the arrow of the Y axis points (+Y side) is one axial side, and the side of the axial direction Y opposite to the side toward which the arrow of the Y axis points (-Y side) is the other axial side. The radial direction centered on the central axis J is simply referred to as the "radial direction." The circumferential direction centered on the central axis J is simply referred to as the "circumferential direction." The Z axis indicates the up-down direction when the electric pump 100 of the embodiment is installed. The side of the up-down direction Z toward which the arrow of the Z axis points (+Z side) is the upper side, and the side of the up-down direction Z opposite to the side toward which the arrow of the Z axis points (-Z side) is the lower side. The X axis indicates a direction perpendicular to both the axial direction Y and the up-down direction Z.

[0010] The posture of the electric pump 100 in the vertical direction Z described below is an example, and the actual positional relationship may be one other than the positional relationship indicated by these names.

[0011] (electric pump) 1 is a cross-sectional view of an electric pump 100 according to this embodiment. The electric pump 100 is attached to, for example, a device mounted on a vehicle. The device to which the electric pump 100 is attached may be an automatic transmission or a drive unit that drives an axle of the vehicle.

[0012] In the following description, the device to which the electric pump 100 is attached is referred to as the attachment target device 5. The electric pump 100 is, for example, an electric oil pump that supplies oil to devices mounted on a vehicle. The electric pump 100 is connected to a flow path provided in the attachment target device 5 via an intake port 44c and an outlet port 43c.

[0013] The electric pump 100 includes a motor unit 3, a control unit 70, a pump unit 40, and a housing 10. The housing 10 accommodates the motor unit 3, the control unit 70, and the pump unit 40.

[0014] (Motor section) The motor unit 3 is accommodated inside the motor housing 11. In the axial direction Y, the motor unit 3 is disposed on one axial side (+Y) of the control unit 70 and on the other axial side (-Y) of the pump unit 40. The motor unit 3 has a rotor 20, a stator 30, and a terminal unit 60.

[0015] The rotor 20 is rotatable about a central axis J. The rotor 20 has a rotor core 21, a magnet 22, and a shaft 23. That is, the motor unit 3 has the shaft 23 that is rotatable about the central axis J. The magnet 22 and the shaft 23 are fixed to the rotor core 21.

[0016] The shaft 23 extends in the axial direction Y around the central axis J. The shaft 23 of this embodiment is a hollow shaft. The shaft 23 has a hollow portion 23h. The hollow portion 23h has a first opening 23a that opens at an end of the shaft 23 on the other axial side (-Y) and a second opening 23b that opens at an end of the shaft 23 on one axial side (+Y).

[0017] The stator 30 is disposed radially outside the rotor 20. The stator 30 faces the rotor 20 with a gap in the radial direction. The stator 30 has a stator core 31, an insulator 32, and a coil portion 33. The stator core 31 surrounds the rotor core 21 from the radial outside. The outer peripheral surface of the stator core 31 is fixed to the cylindrical portion 11a of the motor housing 11. The stator core 31 has an annular core back portion 31a and a plurality of teeth 31b that protrude radially inward from the inner peripheral surface of the core back portion 31a. The plurality of teeth 31b are disposed at equal intervals along the circumferential direction. The coil portion 33 is attached to the teeth 31b via the insulator 32. The coil portion 33 is configured by winding a coil wire. The coil wire is drawn out from the coil portion 33.

[0018] The coil wires drawn out from the stator 30 are connected to the terminal unit 60. The terminal unit 60 is disposed between the stator 30 and the control unit 70. The terminal unit 60 has a plurality of terminal members. The terminal members relay the coil wires to the control unit 70.

[0019] (circuit board) The control unit 70 is located on the other axial side (-Y) of the motor unit 3. The control unit 70 is connected to the motor unit 3. The control unit 70 controls the power supplied to the coil unit 33. In this way, the control unit 70 controls the motor unit 3. The control unit 70 has a circuit board 71 that extends in a direction perpendicular to the axial direction Y. The circuit board 71 is arranged on the central axis J. A control IC, an inverter, a power supply circuit, and the like that drive and control the motor unit 3 are mounted on the circuit board 71. Terminal members of the terminal unit 60 are connected to the circuit board 71.

[0020] (housing) The housing 10 accommodates the motor section 3, the control section 70, and the pump section 40 inside. The housing 10 is provided with a motor chamber 10A and a pump chamber 10B. The motor section 3 and the control section 70 are disposed in the motor chamber 10A. On the other hand, the pump section 40 is disposed in the pump chamber 10B. The end of the shaft 23 on one axial side (+Y) is disposed in the pump chamber 10B. On the other hand, the end of the shaft 23 on the other axial side (-Y) is disposed in the motor chamber 10A.

[0021] The housing 10 has a lid portion 13, a motor housing 11, and a pump cover 19. The lid portion 13, the motor housing 11, and the pump cover 19 are separate members. The lid portion 13 is fixed to the other axial end of the motor housing 11. The pump cover 19 is fixed to one axial end of the motor housing 11. The motor chamber 10A is a space surrounded by the lid portion 13 and the motor housing 11. The pump chamber 10B is a space surrounded by the pump cover 19 and the motor housing 11.

[0022] (Lid) The lid portion 13 accommodates the control unit 70 therein. The lid portion 13 also covers the motor chamber 10A from the other axial side (-Y). The lid portion 13 is made of, for example, resin. The lid portion 13 has a board surrounding portion 13a, a plurality of fixing claw portions 13b, and a board cover portion 13c.

[0023] The substrate surrounding portion 13a is substantially annular and centered on the central axis J. The substrate surrounding portion 13a surrounds the control unit 70 from the radially outer side. A groove 13g is provided on the outer peripheral surface of the substrate surrounding portion 13a. The groove 13g opens radially outward. The groove 13g is provided around the entire circumference of the outer peripheral surface of the substrate surrounding portion 13a. An O-ring 2b is accommodated in the groove 13g. The O-ring 2b extends in an annular shape and is centered on the central axis J.

[0024] The fixed claws 13b extend from the substrate surrounding portion 13a toward one axial side (+Y). The fixed claws 13b are arranged side by side along the circumferential direction. The tips of the fixed claws 13b are provided with protrusions that protrude radially inward.

[0025] The board cover portion 13c covers the control unit 70 from the other axial side. In this way, the board cover portion 13c protects the control unit 70. In this embodiment, the board cover portion 13c is adhesively fixed to the board enclosure portion 13a from the other axial side (-Y).

[0026] (Motor housing) The motor housing 11 has a generally cylindrical shape and extends in the axial direction Y around a central axis J. The motor housing 11 accommodates the motor section 3 and the pump section 40. The motor housing 11 has a cylindrical section 11a, a bottom wall section 11d, and a pump surrounding section 11h.

[0027] The cylindrical portion 11a has a cylindrical shape that extends in the axial direction Y around the central axis J. The cylindrical portion 11a surrounds the motor portion 3 from the radial outside. The cylindrical portion 11a also surrounds the motor chamber 10A from the radial outside. A lid portion 13 is connected to the end of the cylindrical portion 11a on the other axial side (-Y). As a result, the opening of the cylindrical portion 11a on the other axial side (-Y) is covered by the lid portion 13.

[0028] An engagement groove 11c is provided on the outer peripheral surface of the cylindrical portion 11a. The engagement groove 11c is provided around the entire circumference of the outer peripheral surface of the cylindrical portion 11a. The engagement groove 11c opens radially outward. The engagement groove 11c is located at the end of the outer peripheral surface of the cylindrical portion 11a on the other axial side (-Y). A fixing claw 13b is arranged radially outward from the end of the cylindrical portion 11a on one axial side (+Y). A protrusion of the fixing claw 13b engages with the engagement groove 11c. This connects the cover portion 13 to the motor housing 11.

[0029] The bottom wall portion 11d extends in a direction intersecting the axial direction Y. The bottom wall portion 11d is substantially annular in shape with the central axis J as its center. The radial outer edge of the surface of the bottom wall portion 11d facing the other axial side is connected to one axial side (+Y) of the cylindrical portion 11a. The bottom wall portion 11d is located on one axial side (+Y) of the motor chamber 10A and on the other axial side (-Y) of the pump chamber 10B. The bottom wall portion 11d separates the motor chamber 10A and the pump chamber 10B.

[0030] A shaft support hole 11j is provided in the bottom wall portion 11d. The shaft support hole 11j penetrates the bottom wall portion 11d in the axial direction Y. As a result, the shaft support hole 11j connects the motor chamber 10A and the pump chamber 10B.

[0031] The shaft support hole 11j is circular and has a center on the central axis J. The shaft 23 is passed through the shaft support hole 11j. The inner diameter of the shaft support hole 11j is slightly larger than the outer diameter of the shaft 23. The shaft support hole 11j rotatably supports the shaft 23 on its inner circumferential surface. That is, the bottom wall portion 11d functions as a sliding bearing.

[0032] A shaft support portion 11e is provided on the surface of the other axial side (-Y) of the bottom wall portion 11d. The shaft support portion 11e is cylindrical and protrudes from the bottom wall portion 11d toward the other axial side (-Y). The shaft support portion 11e extends along the inner edge of the shaft support hole 11j. The inner circumferential surface of the shaft support portion 11e is continuously connected to the shaft support hole 11j. In other words, the inner circumferential surface of the shaft support portion 11e forms part of the inner circumferential surface of the shaft support hole 11j.

[0033] The bottom wall portion 11d covers the pump portion 40 from the other axial side (-Y). The bottom wall portion 11d has a first opposing surface 11f that faces one axial side (+Y) and faces the pump portion 40. The first opposing surface 11f is provided with a first suction side groove 44a, a first discharge side groove (third recess) 43a, and a first communication groove (second groove) 11s. The first suction side groove 44a, the first discharge side groove 43a, and the first communication groove 11s are recessed toward the other axial side (-Y).

[0034] FIG. 2 is a front view of the first opposing surface 11f of this embodiment. As shown in FIG. 2, the first suction side groove 44a and the first discharge side groove 43a are each arc-shaped grooves extending in the circumferential direction of the central axis J. The first suction side groove 44a and the first discharge side groove 43a open to one axial side (+Y). The first suction side groove 44a and the first discharge side groove 43a are provided at different circumferential positions. The first suction side groove 44a and the first discharge side groove 43a are located on opposite sides of the central axis J.

[0035] The first communication groove 11s extends linearly in the radial direction. The radially inner end of the first communication groove 11s opens into the shaft support hole 11j. The radially outer end of the first communication groove 11s opens into the first discharge groove 43a. The opening of the first communication groove 11s in the first discharge groove 43a is located approximately in the center of the first discharge groove 43a in the longitudinal direction.

[0036] In this embodiment, a step 11n is provided at the radially inner end of the first communicating groove portion 11s. The depth dimension of the first communicating groove portion 11s is increased at the step 11n. That is, the position of the bottom surface of the first communicating groove portion 11s is recessed toward the other axial side (-Y) at the step 11n compared to other portions. According to this embodiment, by providing the step 11n at the radially inner end of the first communicating groove portion 11s, the radially inner opening of the first communicating groove portion 11s can be ensured to be wide in the axial direction. This allows the fluid to be supplied to a wide range in the axial direction relative to the outer peripheral surface of the shaft 23. This makes it easier for the fluid to lubricate between the inner peripheral surface of the shaft support hole 11j and the outer peripheral surface of the shaft 23.

[0037] The bottom surface of the step portion 11n may be inclined radially inward toward the other axial side (-Y). In this case, the fluid in the first communicating groove portion 11s can be smoothly supplied to the shaft support hole 11j at the step portion 11n.

[0038] Furthermore, the groove width of the step portion 11n may gradually increase radially inward. In this case, the fluid can be supplied to a wider area in the circumferential direction relative to the outer circumferential surface of the shaft 23. This makes it easier for the fluid to lubricate the area between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23.

[0039] As shown in FIG. 1, the pump surrounding portion 11h is cylindrical and protrudes from the bottom wall portion 11d to one side in the axial direction. The pump surrounding portion 11h surrounds the pump portion 40 from the radially outer side. That is, the pump chamber 10B is provided radially inside the pump surrounding portion 11h. The pump surrounding portion 11h opens to one side in the axial direction. The inner circumferential surface of the pump surrounding portion 11h is circular and eccentric with respect to the central axis J. The inner circumferential surface of the pump surrounding portion 11h faces the outer circumferential surface of the outer rotor 42. The inner circumferential surface of the pump surrounding portion 11h rotatably supports the outer circumferential surface of the outer rotor 42.

[0040] (Pump cover) The pump cover 19 is substantially disk-shaped and centered on the central axis J. The pump cover 19 is disposed on one axial side (+Y) of the pump section 40. The pump cover 19 covers the pump section 40 from one axial side (+Y). Therefore, the pump cover 19 and the bottom wall section 11d sandwich the pump section 40 from both axial sides. The pump cover 19 is fixed to the end of the inner circumferential surface of the pump surrounding section 11h on one axial side (+Y). The pump cover 19 closes the opening of the pump surrounding section 11h from one axial side. That is, the pump cover 19,

[0041] The pump cover 19 has a second opposing surface (inner wall surface) 19f, a suction section 19a, an suction port 44c, and a discharge port 43c. The second opposing surface 19f faces the other axial side (-Y) and faces the pump section 40. That is, the housing 10 has the second opposing surface 19f that covers the pump chamber 10B from one axial side (+Y).

[0042] The second opposing surface 19f is provided with a second suction side groove (second recess) 44b, a second discharge side groove 43b, an opposing recess (first recess) 19b, and a second communication groove (first groove) 19g. The second suction side groove 44b, the second discharge side groove 43b, the opposing recess 19b, and the second communication groove 19g are provided on the surface of the pump cover 19 facing the other axial side (-Y).

[0043] FIG. 3 is a front view of the second opposing surface of this embodiment. The second suction side groove 44b and the second discharge side groove 43b are grooves that extend in the circumferential direction of the central axis J. The second suction side groove 44b and the second discharge side groove 43b are located radially outward of the opposing recess 19b. The second suction side groove 44b and the second discharge side groove 43b are recessed toward one axial side (+Y). The second suction side groove 44b and the second discharge side groove 43b open to the other axial side (-Y). The second suction side groove 44b and the second discharge side groove 43b are located at different circumferential positions. In this embodiment, the second suction side groove 44b and the second discharge side groove 43b are located on opposite sides of the central axis J. An intake port 44c opens at the bottom surface of the second suction side groove 44b. That is, the second suction side groove 44b is connected to the suction port 44c. The discharge port 43c opens at the bottom surface of the second discharge side groove 43b. That is, the second suction side groove 44b is connected to the discharge port 43c.

[0044] As shown in FIGS. 2 and 3, the second suction side groove 44b and the first suction side groove 44a have substantially the same shape. The second suction side groove 44b overlaps with the first suction side groove 44a when viewed in the axial direction Y. Similarly, the second discharge side groove 43b and the first discharge side groove 43a have substantially the same shape. The second discharge side groove 43b overlaps with the first discharge side groove 43a when viewed in the axial direction Y. The second suction side groove 44b, the first suction side groove 44a, the second discharge side groove 43b, the first discharge side groove 43a, the first communicating groove 11s, the opposing recess 19b, and the second communicating groove 19g are part of the pump chamber 10B.

[0045] 1, the opposing recess 19b is located on the central axis J. The opposing recess 19b faces the second opening 23b of the shaft 23 in the axial direction. The opposing recess 19b of this embodiment has a circular shape centered on the central axis J when viewed in the axial direction. However, the shape of the opposing recess 19b is not limited to this embodiment.

[0046] The second communication groove 19g extends linearly in the radial direction. The radially inner end of the second communication groove 19g opens into the opposing recess 19b. The radially outer end of the second communication groove 19g opens into the second suction side groove 44b. This allows the second communication groove 19g to connect the opposing recess 19b and the second suction side groove 44b.

[0047] 3, second communication groove 19g extends below the water surface (XY plane). Connection 15a between second communication groove 19g and second suction side groove 44b is located approximately in the center of the second suction side groove 44b in the longitudinal direction. In addition, the opening of suction port 44c in second suction side groove 44b is located above connection 15a between second communication groove 19g and second suction side groove 44b.

[0048] As shown in FIG. 1, the suction portion 19a is cylindrical and protrudes toward one axial side (+Y) from a surface of the pump cover 19 facing that side. The suction port 44c is provided on the tip surface of the suction portion 19a. The suction port 44c is connected to the bottom surface of the second suction side groove portion 44b. The suction port 44c draws fluid from outside the electric pump 100. The suction port 44c allows the fluid to flow into the suction chamber A2 of the pump chamber 10B.

[0049] The discharge port 43c is provided on a surface of the pump cover 19 facing one axial side (+Y). The discharge port 43c is connected to the bottom surface of the second discharge groove portion 43b. The discharge port 43c discharges the compressed fluid to the outside of the electric pump 100. The discharge port 43c discharges the fluid from the compression chamber A1 of the pump chamber 10B.

[0050] (Pump section) The pump unit 40 is disposed on one axial side (+Y) of the motor unit 3. The pump unit 40 is connected to the end of the shaft 23 on one axial side (+Y). The pump unit 40 is driven by the power of the motor unit 3. The pump unit 40 draws in fluid such as oil from the outside, compresses the drawn fluid, and discharges it. In other words, the pump unit 40 pumps the fluid.

[0051] The pump section 40 of this embodiment is a trochoid pump. The pump section 40 includes an inner rotor 41 and an outer rotor 42. The outer rotor 42 is disposed radially outward of the inner rotor 41. The inner rotor 41 and the outer rotor 42 each have a trochoid tooth profile. The tooth profile of the inner rotor 41 and the tooth profile of the outer rotor 42 mesh at one circumferential point. The outer rotor 42 is held on the inner circumferential surface of the pump enclosure 11h. The outer rotor 42 surrounds the inner rotor 41 from the radially outer side over the entire circumferential circumference. The inner rotor 41 is connected to an end of the shaft 23 on one axial side (+Y). The inner rotor 41 rotates around the central axis J integrally with the shaft 23, radially inside the outer rotor 42. The outer rotor 42 rotates eccentrically around the central axis J while sliding along the inner circumferential surface of the pump enclosure 11h.

[0052] The internal space of the second suction side groove 44b and the internal space of the first suction side groove 44a are connected to the gap G between the inner rotor 41 and the outer rotor 42 from both sides in the axial direction Y. In the following description, the internal spaces of the second suction side groove 44b and the first suction side groove 44a, which are connected to each other as a single continuous space, are referred to as suction chamber A2. The suction chamber A2 is connected to the suction port 44c.

[0053] The internal space of the second discharge groove 43b and the internal space of the first discharge groove 43a are connected to the gap G between the inner rotor 41 and the outer rotor 42 from both sides in the axial direction Y. In the following description, the internal spaces of the second discharge groove 43b and the first discharge groove 43a, which are connected to each other as a continuous space, are referred to as compression chamber A1. Compression chamber A1 is connected to the discharge port 43c.

[0054] The suction port 44c, the suction chamber A2, the compression chamber A1, and the discharge port 43c function as part of the pump section 40. That is, the pump section 40 has the suction port 44c, the suction chamber A2, the compression chamber A1, and the discharge port 43c. The suction port 44c draws in fluid from the outside. The suction chamber A2 is connected to the suction port 44c. The compression chamber A1 pumps the fluid. The discharge port 43c is connected to the compression chamber A1 and discharges the fluid to the outside.

[0055] As the pump section 40 is driven, the gap G between the inner rotor 41 and the outer rotor 42 moves around the central axis J. As a result, the pressure in the suction chamber A2 decreases, and fluid flows into the suction chamber A2 and the gap G from the suction port 44c. As the gap G moves in the circumferential direction, the pump section 40 moves the fluid from the suction chamber A2 to the compression chamber A1. As a result, the pressure in the compression chamber A1 increases, and the fluid in the compression chamber A1 is discharged from the discharge port 43c.

[0056] (supply route and return route) The housing 10 is provided with supply paths F1a and F1b and a return path F2. The supply paths F1a and F1b allow fluid to flow from the pump chamber 10B into the motor chamber 10A. This allows fluid to be stored in the pump chamber 10B to a certain height. The fluid in the pump chamber 10B circulates within the pump chamber 10B and cools the motor section 3 and the control section 70 arranged in the pump chamber 10B. The return path F2 returns the fluid from the motor chamber 10A to the pump chamber 10B. The fluid returned to the pump chamber 10B is discharged from the discharge port 43c together with other fluids.

[0057] In this embodiment, the first discharge groove 43a is connected to the first communication groove 11s. That is, the radially outer end of the first communication groove 11s is connected to the compression chamber A1. The radially inner end of the first communication groove 11s is connected to the end of the shaft support hole 11j on one axial side (+Y). The end of the shaft support hole 11j on the other axial side (-Y) opens to the motor chamber 10A. In this way, the first communication groove 11s and the shaft support hole 11j connect the compression chamber A1 and the pump chamber 10B.

[0058] When the electric pump 100 is driven, the pressure of the fluid increases in the compression chamber A1. This increase in pressure causes the fluid to pass through the first communication groove 11s and the shaft support hole 11j and flow into the motor chamber 10A. In other words, the first communication groove 11s and the shaft support hole 11j function as a first supply path F1a that moves the fluid from the pump chamber 10B to the motor chamber 10A.

[0059] The shaft 23 is disposed in the shaft support hole 11j. Therefore, a path connecting the pump chamber 10B and the motor chamber 10A inside the shaft support hole 11j is provided between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23. That is, in this embodiment, a portion of the supply paths F1a, F1b is provided between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23.

[0060] The electric pump 100 of this embodiment is housed in a recess 5a of the device 5 to which it is to be attached. The recess 5a is filled with a fluid. An opening 5b connected to a flow path in the device 5 to which it is to be attached is provided on the inner circumferential surface of the recess 5a. The discharge port 43c of the electric pump 100 discharges the fluid into the recess 5a. This increases the pressure in the recess 5a, and the fluid is pressure-fed into the flow path of the device 5 to which it is to be attached from the opening 5b.

[0061] FIG. 4 is a partial cross-sectional view of the electric pump 100 of this embodiment. The cylindrical portion 11a of the motor housing 11 has an end face 11t facing the other axial side (-Y). The cover portion 13 has a third opposing surface 13t that faces the end face 11t in the axial direction. A small gap K is provided between the end face 11t and the third opposing surface 13t. The dimension of the gap K in the axial direction Y is within the dimensional tolerance range of the motor housing 11 and the cover portion 13. The dimension of the gap K in the axial direction Y also varies depending on the circumferential position. The gap K connects the motor chamber 10A with the external space of the housing 10.

[0062] An O-ring 2b is disposed on the outer peripheral surface of the housing 10 on one axial side (+Y) of the gap K. The O-ring 2b is compressed between the bottom surface of the groove portion 13g and the inner peripheral surface of the recessed portion 5a. The O-ring 2b restricts the passage of fluids and the like between the outer peripheral surface of the cylindrical portion 11a and the inner peripheral surface of the recessed portion 5a on the other axial side (-Y) of the gap K. According to this embodiment, it is possible to prevent moisture, dust, and the like that enter through the opening of the recessed portion 5a from entering the motor chamber 10A via the gap K.

[0063] The interior of the recess 5a where the discharge port 43c opens is connected to the compression chamber A1, and the fluid pressure is increased similarly to that in the compression chamber A1. Therefore, a portion of the fluid discharged from the discharge port 43c flows into the motor chamber 10A through the gap K. That is, the gap K functions as the second supply path F1b. In this embodiment, the gap K constituting the second supply path F1b is provided between surfaces facing each other in the axial direction Y, but the gap K may also be provided between surfaces facing each other in the radial direction.

[0064] In this embodiment, the opposing recess 19b, the second communicating groove 19g, and the second suction-side groove 44b constitute a flow path 15 that connects the second opening 23b of the shaft 23 to the suction port 44c. That is, the housing 10 has the flow path 15. The flow path 15 also has the opposing recess 19b, the second communicating groove 19g, and the second suction-side groove 44b. The flow path 15 also connects the second opening 23b to the suction port 44c. The hollow portion 23h of the shaft 23 opens to the motor chamber 10A at the first opening 23a and to the pump chamber 10B at the second opening 23b. Therefore, the flow path 15 and the hollow portion 23h connect the motor chamber 10A to the suction port 44c of the pump chamber 10B.

[0065] When the electric pump 100 is driven, the fluid pressure in the suction chamber A2 decreases, causing the pump section 40 to draw in the fluid through the suction port 44c. At the same time, the fluid in the motor chamber 10A is drawn into the suction chamber A2 through the hollow section 23h and the flow path section 15. In other words, the hollow section 23h and the flow path section 15 function as a return path F2 that moves the fluid from the motor chamber 10A to the pump chamber 10B.

[0066] In this embodiment, the flow path cross-sectional area of ​​the return path F2 is larger than the flow path cross-sectional areas of the supply paths F1a and F1b. Here, the "flow path cross-sectional areas" of the supply paths F1a and F1b and the return path F2 are used as indicators of the magnitude of flow path resistance in the supply paths F1a and F1b and the return path F2. The "flow path cross-sectional areas" of the supply paths F1a and F1b and the return path F2 represent the ease of fluid flow in the supply paths F1a and F1b and the return path F2. The flow path cross-sectional areas of the supply paths F1a and F1b represent the smallest flow path cross-sectional area in the entire length of the supply paths F1a and F1b. Furthermore, if the supply paths F1a and F1b include multiple branched paths, the flow path cross-sectional area of ​​the supply paths F1a and F1b is the sum of the smallest flow path cross-sectional areas of each branched path. Similarly, the flow path cross-sectional area of ​​the return path F2 represents the smallest flow path cross-sectional area in the entire length of the return path F2. Furthermore, when the return path F2 includes a plurality of branched paths, the flow path cross-sectional area of ​​the return path F2 is the sum of the smallest flow path cross-sectional areas of the branched paths.

[0067] In this embodiment, the supply paths F1a and F1b include two paths (a first supply path F1a and a second supply path F1b). The first supply path F1a in this embodiment has the smallest cross-sectional area inside the shaft support hole 11j. Therefore, the flow path cross-sectional area of ​​the first supply path F1a is the area of ​​a cross section perpendicular to the axial direction Y of the gap between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23. Furthermore, the second supply path F1b in this embodiment has the smallest cross-sectional area at the gap K. The flow path cross-sectional area of ​​the second supply path F1b in this embodiment is the area of ​​the gap K over the entire circumferential length. Furthermore, the total flow path cross-sectional area of ​​the supply paths F1a and F1b is the sum of the flow path cross-sectional area of ​​the first supply path F1a and the flow path cross-sectional area of ​​the second supply path F1b.

[0068] In this embodiment, the return path F2 has only one path. The return path F2 in this embodiment has the smallest cross-sectional area inside the second communication groove portion 19g. In this embodiment, the flow path cross-sectional area of ​​the return path F2 is the cross-sectional area of ​​the second communication groove portion 19g in a cross section perpendicular to the radial direction.

[0069] During operation, the electric pump 100 of this embodiment sends fluid compressed in the compression chamber A1 to the motor chamber 10A via the supply paths F1a and F1b, and also draws fluid from the motor chamber 10A into the suction chamber A2 via the return path F2. If the flow rate of fluid sent to the motor chamber 10A via the supply paths F1a and F1b is greater than the flow rate of fluid discharged from the motor chamber 10A via the return path F2, the pressure of the fluid in the motor chamber 10A increases. If the pressure of the fluid in the motor chamber 10A increases too much, the load on the connection between the fixing claw 13b and the locking groove 11c increases, which could cause the cover 13 and the motor housing 11 to become disengaged. Furthermore, if the pressure of the fluid in the motor chamber 10A increases too much, the housing 10 itself could be damaged. In addition, if the pressure of the fluid in the motor chamber 10A becomes too high, the force that the rotor 20 receives from the fluid in the motor chamber 10A becomes uneven in the circumferential direction, which may cause the shaft 23 to tilt and reduce the rotational efficiency of the shaft 23. For this reason, in the electric pump 100, it is preferable to suppress an increase in the pressure of the fluid in the motor chamber 10A.

[0070] In this embodiment, the cross-sectional area of ​​the return path F2 is larger than the cross-sectional area of ​​the supply paths F1a and F1b. Therefore, the return path F2 can have a smaller flow resistance than the supply paths F1a and F1b. This embodiment prevents the flow rate of fluid discharged from the motor chamber 10A through the return path F2 from becoming smaller than the flow rate of fluid sent to the motor chamber 10A through the supply paths F1a and F1b. As a result, an increase in fluid pressure in the motor chamber 10A can be prevented, which can prevent disconnection between the components constituting the housing 10 and damage to the housing 10. Furthermore, tilting of the shaft 23 due to an increase in fluid pressure in the motor chamber 10A can be prevented, thereby maintaining the driving efficiency of the electric pump 100.

[0071] In this embodiment, the shaft 23 has a hollow portion 23h that opens to the motor chamber 10A at a first opening 23a and to the pump chamber 10B at a second opening 23b. The housing 10 also has a flow path 15 that connects the second opening 23b of the hollow portion 23h to the suction port 44c. The return path F2 is provided in the hollow portion 23h of the shaft 23 and the flow path 15. According to this embodiment, the motor chamber 10A and the suction port 44c are connected to each other via the hollow portion 23h and the flow path 15. Therefore, negative pressure at the suction port 44c can be used to draw fluid from the motor chamber 10A into the pump chamber 10B. This promotes fluid circulation within the motor chamber 10A and improves the cooling efficiency of the motor section 3 disposed in the motor chamber 10A.

[0072] Furthermore, according to this embodiment, the opening of the return path F2 in the motor chamber 10A is located at the end of the other axial side (-Y) of the shaft 23. Therefore, the return path F2 can suck fluid from the other axial side (-Y) of the motor unit 3. When the first supply path F1a is disposed on one axial side (+Y) of the motor unit 3, fluid can flow through gaps in the motor unit 3 in the motor chamber 10A from the other axial side (-Y) to the one axial side (+Y), allowing the motor unit 3 to be efficiently cooled.

[0073] In this embodiment, the housing 10 has a second opposing surface 19f that covers the pump chamber 10B from one axial side (+Y), and the flow path portion 15 has an opposing recess 19b, a second suction side groove 44b, and a second communication groove 19g provided in the second opposing surface 19f. The opposing recess 19b faces the second opening 23b. The second suction side groove 44b connects to the suction port 44c. The second communication groove 19g connects the opposing recess 19b and the second suction side groove 44b. According to this embodiment, the fluid that passes through the hollow portion 23h of the shaft 23 and flows into the pump chamber 10B can be guided to the suction port 44c by the opposing recess 19b, the second suction side groove 44b, and the second communication groove 19g provided in the second opposing surface 19f. This allows the fluid to be smoothly discharged from the motor chamber 10A through the return path F2.

[0074] In this embodiment, the connection portion 15a between the second communication groove 19g and the second suction side groove 44b is located below the opening of the suction port 44c in the second suction side groove 44b. According to this embodiment, the second communication groove 19g is connected to the second suction side groove 44b below the suction port 44c. The suction port 44c is connected to the flow path of the target device 5 and filled with fluid. Therefore, even in the suction chamber A2 inside the second suction side groove 44b, the region below the second suction side groove 44b is easily filled with fluid. Therefore, connecting the second communication groove 19g to the second suction side groove 44b below the suction port 44c makes it easier to fill the second communication groove 19g with fluid. That is, according to this embodiment, air is prevented from remaining in the second communication groove 19g, and the negative pressure in the suction chamber A2 is used to easily draw fluid from the motor chamber 10A to the pump chamber 10B.

[0075] In this embodiment, the supply paths F1a and F1b are connected to the compression chamber A1 at the pump chamber 10B. Since the pressure of the fluid is increased in the compression chamber A1, the fluid can be smoothly moved from the pump chamber 10B to the motor chamber 10A through the supply paths F1a and F1b.

[0076] As shown in FIG. 1, the first supply path F1a, which is at least a part of the supply paths F1a and F1b of this embodiment, is provided between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23. The inner circumferential surface of the shaft support hole 11j supports the outer circumferential surface of the shaft 23 while allowing it to slide along the inner circumferential surface. According to this embodiment, by providing the first supply path F1a in the gap between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23, it is easy to make the flow path cross-sectional area of ​​the first supply path F1a smaller than the flow path cross-sectional area of ​​the return path F2. According to this embodiment, it is easy to suppress an increase in pressure in the motor chamber 10A.

[0077] Furthermore, if the flow path cross-sectional areas of the supply paths F1a and F1b are large, a large amount of fluid flows from the compression chamber A1 to the motor chamber 10A, and the pressure in the compression chamber A1 decreases, thereby reducing the amount of fluid discharged through the discharge port 43c. According to this embodiment, by providing the first supply path F1a in the gap between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23, the flow path cross-sectional area of ​​the first supply path F1a can be made sufficiently small, thereby improving the discharge efficiency of the electric pump 100.

[0078] Furthermore, according to this embodiment, by providing the first supply path F1a in the gap between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23, the fluid lubricates the gap between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23. According to this embodiment, the frictional resistance between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23 can be reduced.

[0079] In this embodiment, the first opposing surface 11f is provided with a first discharge groove 43a that constitutes at least a portion of the inner wall of the compression chamber A1, and a first communication groove 11s that connects the first discharge groove 43a to the inner circumferential surface of the shaft support hole 11j. Furthermore, the first supply path F1a, which is at least a portion of the supply paths F1a and F1b, is provided within the first communication groove 11s. According to this embodiment, the fluid that has been pressurized in the compression chamber A1 can be sent between the inner circumferential surface of the shaft support hole 11j and the outer circumferential surface of the shaft 23 via the first communication groove 11s.

[0080] In this embodiment, the housing 10 has a cylindrical portion 11a and a lid portion 13 that covers an opening on the other axial side (-Y) of the cylindrical portion 11a. A second supply path F1b, which is at least a part of the supply paths F1a and F1b, is provided in the gap K between the cylindrical portion 11a and the lid portion 13. The housing 10 of this embodiment is provided with a plurality of branched supply paths F1a and F1b. This embodiment allows a larger amount of fluid to be sent to the motor chamber 10A. This improves the cooling efficiency of each part of the motor chamber 10A (the motor section 3 and the control section 70).

[0081] Fluid flows into the motor chamber 10A via supply paths F1a and F1b and flows out of the motor chamber 10A via return path F2. In the motor chamber 10A, the fluid accumulates at least up to the height of the opening of the return path F2 in the motor chamber 10A. In this embodiment, the return path F2 opens into the motor chamber 10A at a first opening 23a of the shaft 23. By arranging components arranged in the motor chamber 10A below the central axis J, they can be cooled by the fluid accumulating in the lower part of the motor chamber 10A.

[0082] In this embodiment, the control unit 70 is disposed in the motor chamber 10A. At least a portion of the control unit 70 is located below the first opening 23a. According to this embodiment, at least a portion of the control unit 70 can be immersed in the fluid accumulated in the lower part of the motor chamber 10A, which makes it possible to effectively cool the control unit 70.

[0083] In this embodiment, the control unit 70 faces the first opening 23a in the axial direction. According to this embodiment, the fluid around the control unit 70, which has been warmed by immersion of the control unit 70, can be sucked through the first opening 23a and returned to the pump chamber 10B. That is, according to this embodiment, the fluid whose temperature has increased in the motor chamber 10A can be returned to the pump chamber 10B. This makes it easier to maintain a low temperature of the fluid in the motor chamber 10A, thereby improving the cooling efficiency of the motor unit 3 and the control unit 70.

[0084] The present invention is not limited to the above-described embodiment and its modifications, and other configurations and methods may be adopted within the scope of the technical idea of ​​the present invention.

[0085] For example, the configurations of the supply path and return path in the above-described embodiment and its modified examples are merely examples, and are not limited to the above-described embodiment and its modified examples as long as they can transport fluid between the pump chamber and the motor chamber, respectively.

[0086] In the above-described embodiment, the connection between the cover and the motor housing is based on the relationship between the fixing claw and the locking groove. However, the connection structure between the cover and the motor housing is not limited to the above-described embodiment.

[0087] The electric pump to which the present invention is applied is not particularly limited in its application. The type of fluid pumped by the electric pump is not particularly limited, and may be water, etc. The electric pump may be mounted on equipment other than a vehicle.

[0088] The present technology can be configured as follows. (1) An electric pump comprising: a motor section having a shaft rotatable about a central axis; a pump section connected to one axial end of the shaft and driven by the power of the motor section to pump a fluid; and a housing that accommodates the motor section and the pump section, wherein the housing is provided with a motor chamber in which the motor section is disposed, a pump chamber in which the pump section is disposed, a supply path for allowing the fluid to flow from the pump chamber into the motor chamber, and a return path for returning the fluid from the motor chamber to the pump chamber, the shaft has a hollow section that opens into the motor chamber at a first opening and into the pump chamber at a second opening, the pump section has an intake port that draws in the fluid from the outside and an outlet port that discharges the fluid to the outside, the housing has a flow path section that connects the second opening and the intake port, and the return path is provided in the hollow section and the flow path section. (2) The electric pump described in (1), wherein the housing has an inner wall surface that covers the pump chamber from one axial side, and the inner wall surface is provided with a first recess facing the second opening, a second recess located radially outside the first recess and connected to the suction port, and a first groove portion extending radially to connect the first recess and the second recess, and the flow path portion has the first recess, the second recess, and the first groove portion. (3) The electric pump according to (2), wherein a connection portion between the first groove portion and the second recess portion is located below an opening of the suction port in the first groove portion. (4) The electric pump according to (1), wherein the pump section has a compression chamber connected to the discharge port and compresses and feeds the fluid, and the supply path is connected to the compression chamber. (5) An electric pump as described in (4), wherein the housing has a bottom wall portion extending in a direction intersecting the axial direction to separate the motor chamber and the pump chamber, the bottom wall portion is provided with a shaft support hole extending in the axial direction to connect the motor chamber and the pump chamber, the shaft support hole rotatably supports the shaft on its inner circumferential surface, and at least a portion of the supply path is provided between the inner circumferential surface of the shaft support hole and the outer circumferential surface of the shaft. (6) An electric pump as described in (5), wherein a surface of the bottom wall portion facing one axial side is provided with a third recess that forms at least a part of the inner wall portion of the compression chamber, and a second groove portion that connects the third recess with the inner surface of the shaft support hole, and at least a part of the supply path is provided inside the second groove portion. (7) An electric pump as described in (5) or (6), wherein the housing has a cylindrical portion that surrounds the motor portion from the radial outside and a lid portion that is connected to the other axial end of the cylindrical portion and covers the opening on the other axial side of the cylindrical portion, and at least a portion of the supply path is provided in the gap between the cylindrical portion and the lid portion. (8) An electric pump according to any one of (1) to (7), further comprising a control unit disposed in the pump chamber and controlling the motor unit, at least a portion of the control unit being located below the first opening. (9) The electric pump according to (8), wherein the control unit faces the first opening in the axial direction. (10) The electric pump according to any one of (1) to (9), wherein a flow path cross-sectional area of ​​the return path is larger than a flow path cross-sectional area of ​​the supply path. [Explanation of symbols]

[0089] 3...motor portion, 5a...recess, 5b...opening, 10...housing, 10A...motor chamber, 10B...pump chamber, 11a...cylindrical portion, 11d...bottom wall portion, 11j...shaft support hole, 11s...first communicating groove portion (second groove portion), 13...lid portion, 13g...groove portion, 15...flow path portion, 15a...connecting portion, 19b...opposing recess (first recess), 19f...second opposing surface (inner wall surface), 19g...second communicating groove portion (first groove portion), 23...shaft, 23a...first opening, 23b...second opening, 23h...hollow portion, 40...pump portion, 43a...first discharge groove portion (third recess), 43c...discharge port, 44b...second suction groove portion (second recess), 44c...suction port, 70...control portion, 100...electric pump, A1...compression chamber, F2...return path, F1a...supply path, G, K...gap, IC...control, J...central axis, Y...axial direction

Claims

1. a motor unit having a shaft rotatable about a central axis; a pump unit connected to one axial end of the shaft and driven by the power of the motor unit to pump fluid; a housing that accommodates the motor unit and the pump unit, The housing includes: a motor chamber in which the motor unit is disposed; a pump chamber in which the pump unit is disposed; a supply path for allowing the fluid to flow from the pump chamber to the motor chamber; a return path for returning the fluid from the motor chamber to the pump chamber; the shaft has a hollow portion that opens into the motor chamber at a first opening and into the pump chamber at a second opening, The pump unit includes: an intake port for sucking the fluid from the outside; a discharge port for discharging the fluid to the outside, the housing has a flow path portion connecting the second opening and the suction port, The return path is provided in the hollow portion and the flow path portion. Electric pump.

2. the housing has an inner wall surface that covers the pump chamber from one axial side, The inner wall surface has a first recess facing the second opening; a second recess located radially outward of the first recess and connected to the intake port; a first groove portion extending along a radial direction and connecting the first recess portion and the second recess portion; the flow path portion has the first recess, the second recess, and the first groove portion; The electric pump according to claim 1 .

3. a connecting portion between the first groove portion and the second recess portion is located below an opening of the suction port in the first groove portion; The electric pump according to claim 2.

4. the pump portion has a compression chamber that is connected to the discharge port and that pressurizes and feeds the fluid; The supply path is connected to the compression chamber. The electric pump according to claim 1 .

5. the housing has a bottom wall portion extending in a direction intersecting the axial direction and separating the motor chamber and the pump chamber, a shaft support hole extending in the axial direction and connecting the motor chamber and the pump chamber is provided in the bottom wall portion; the shaft support hole rotatably supports the shaft on an inner circumferential surface thereof, At least a portion of the supply path is provided between an inner circumferential surface of the shaft support hole and an outer circumferential surface of the shaft. The electric pump according to claim 4.

6. The surface of the bottom wall portion facing one axial side is a third recess that constitutes at least a part of an inner wall of the compression chamber; a second groove portion connecting the third recess portion and an inner circumferential surface of the shaft support hole, At least a portion of the supply path is provided inside the second groove portion. The electric pump according to claim 5.

7. The housing includes: a cylindrical portion that surrounds the motor portion from the radially outer side; a cover portion connected to the end portion on the other axial side of the cylindrical portion and covering the opening on the other axial side of the cylindrical portion, The electric pump according to claim 5 , wherein at least a portion of the supply path is provided in a gap between the cylindrical portion and the lid portion.

8. a control unit that is disposed in the pump chamber and controls the motor unit; At least a portion of the control unit is located below the first opening. The electric pump according to claim 1 .

9. The control portion faces the first opening portion in the axial direction. The electric pump according to claim 8.

10. The return path has a cross-sectional area larger than the cross-sectional area of ​​the supply path. The electric pump according to any one of claims 1 to 9.

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