Electric pump

Abstract

To provide an electric pump exhibiting high heat radiation effect of a motor.SOLUTION: An electric pump 200 includes a motor 220, a pump mechanism 30, a motor housing, and a pump housing 212. The pump mechanism includes an inner rotor 31 and an outer rotor 32. The pump housing 212 includes a pump storage part 212a for storing the pump mechanism 30, a suction port and a discharge port opened to the outside of the pump housing 212, a suction side flow passage 81 connecting the suction port and the pump storage part 212a, and a discharge side flow passage 82 connecting the discharge port and the pump storage part 212a. The suction port and the discharge port are positioned on the motor side in an axial direction relative to the pump storage part 212a.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, there is known a pump in which a suction port is disposed on one axial side of a shaft extending relative to a space in a gear housing in which a gear is accommodated, and a discharge port is disposed on the other axial side, as described in Patent Document 1. Both the suction port and the discharge port open radially outward from the gear housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6526371 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional pumps have a problem in that when the discharge pressure increases due to continuous operation of the pump, the load on the pump increases and the amount of heat generated by the motor increases. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided a pump mechanism including a motor having a rotor rotatable about a central axis, a pump mechanism connected to the motor, a motor housing that houses the motor, and a pump housing that houses the pump mechanism, wherein the pump housing has an intake port and an exhaust port that open to an outer circumferential surface of the pump housing, an intake side flow path that connects the pump mechanism and the intake port, and a discharge side flow path that connects the pump mechanism and the exhaust port, the discharge side flow path including a first discharge flow path that extends radially outward from the pump mechanism side and toward the exhaust port side; the pump mechanism has a branch flow path branching off from the first discharge flow path and extending along the central axis, a discharge flow path extending from the branch flow path in a direction intersecting the central axis, and a connecting flow path connecting the discharge flow path to the suction side flow path, a relief valve that operates in response to the pressure of fluid in the discharge side flow path is disposed in the branch flow path, the branch flow path, the discharge flow path and the connecting flow path form a relief flow path that returns a portion of the fluid discharged from the pump mechanism to the suction side flow path, and at least a portion of the relief flow path is disposed radially outside of the motor. Effect of the Invention

[0006] According to one aspect of the present invention, there is provided an electric pump having a high heat dissipation effect from a motor. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view of an electric oil pump according to a first embodiment. [Diagram 2] FIG. 2 is an enlarged partial cross-sectional view showing the periphery of the pump mechanism. [Diagram 3] FIG. 3 is a perspective view including a partial cross section showing the structure of the suction port and the discharge port. [Figure 4] FIG. 4 is a perspective view, including a partial cross section, showing radially extending portions of the suction flow passage and the discharge flow passage. [Diagram 5] FIG. 5 is a perspective view including a partial cross section showing the path of the intake side flow passage. [Figure 6]FIG. 6 is a perspective view including a partial cross section showing the path of the discharge side flow passage. [Figure 7] FIG. 7 is a partial cross-sectional view showing the flow path around the relief valve. [Figure 8] FIG. 8 is a perspective view including a partial cross section showing the path of the suction side flow passage in the electric oil pump of the second embodiment. [Figure 9] FIG. 9 is a perspective view including a partial cross section showing the path of the discharge side flow passage. [Figure 10] FIG. 10 is a partial cross-sectional view showing the flow path around the relief valve. [Figure 11] FIG. 11 is a partial cross-sectional view showing a modification of the relief flow passage in the electric pump of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an electric oil pump will be described as one embodiment of the electric pump. The electric oil pump of the first embodiment is used to supply oil (fluid) to devices mounted on a vehicle or the like.

[0009] In each of the drawings referred to below, an XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system as appropriate. In the XYZ coordinate system, the X-axis direction is parallel to the axis of the central axis J shown in Fig. 1. The central axis J is the central axis of a shaft 21 of a motor 220 described later. The Y-axis direction is a direction perpendicular to the X-axis and parallel to the depth direction in Fig. 1. The Z-axis direction is a direction perpendicular to both the X-axis and Y-axis directions and parallel to the up-down direction in Fig. 1. In each of the X-axis, Y-axis, and Z-axis directions, the side toward which the arrow in the figure points is the + side, and the opposite side is the - side.

[0010] In the following description, unless otherwise specified, the direction parallel to the central axis J (X-axis direction) will be simply referred to as the "axial direction." The radial direction centered on the central axis J will be simply referred to as the "radial direction." The circumferential direction centered on the central axis J, i.e., around the axis of the central axis J (θ direction), will be simply referred to as the "circumferential direction."

[0011] Also, the positive side (+X side) in the X-axis direction may be referred to as the "front side". Similarly, the negative side (-X side) in the X-axis direction may be referred to as the "rear side". The front side (+X side) corresponds to one axial side in the present invention. The rear side (-X side) corresponds to the other axial side in the present invention.

[0012] As shown in FIG. 1, the electric oil pump (electric pump) 200 includes a pump body 210, a motor 220, a pump mechanism 30, and a control board 40. The pump body 210 has a motor housing 211 that houses the motor 220, a pump housing 212 that houses the pump mechanism 30, and a board housing 213 that houses the control board 40. In this embodiment, the motor housing 211, the pump housing 212, and the board housing 213 are part of a single member.

[0013] The motor housing 211 is located on the rear side (-X side) of the pump body 210. The motor housing 211 is cylindrical and extends in the axial direction. The motor housing 211 has a first accommodating recess 211a that is a recess that opens to the rear side. The first accommodating recess 211a is closed from the rear side by a motor cover 226, which will be described later.

[0014] The pump housing 212 is located on the front side (+X side) of the pump body 210. The pump housing 212 has a second accommodating recess (pump accommodating portion) 212a consisting of a recess that opens to the front side. The pump mechanism 30 is accommodated in the second accommodating recess 212a. The electric oil pump 200 has a pump cover 212b that closes the second accommodating recess 212a from the front side.

[0015] The board housing 213 is located on a side surface of the motor housing 211 and the pump housing 212. The board housing 213 is located on the illustrated lower side (-Z side) of the motor housing 211 and the pump housing 212. The board housing 213 has a generally rectangular shape when viewed from the radial outside. The board housing 213 has a third accommodating recess 213a that opens toward the illustrated lower side of the pump body 210. A board unit 240, which will be described later, is attached to the board housing 213 from the illustrated lower side.

[0016] The pump body 210 has a first through hole 210a that axially connects the first accommodating recess 211a of the motor housing 211 and the second accommodating recess 212a of the pump housing 212. The pump body 210 has a second through hole 210b that radially connects the first accommodating recess 211a and the third accommodating recess 213a of the board housing 213.

[0017] The motor 220 includes a rotor 22 having a shaft 21, a stator 23, a bus bar assembly 224, a bus bar cover 225, a motor cover 226, a first bearing 27 (bearing) and a second bearing (bearing) 28. In this embodiment, the first bearing 27 and the second bearing 28 are rolling bearings. Either or both of the first bearing 27 and the second bearing 28 may be a sliding bearing. A front end of the shaft 21 is connected to the pump mechanism 30.

[0018] Busbar assembly 224 has a plurality of busbars 224a and a resin busbar holder that holds the plurality of busbars 224a. Busbar assembly 224 has a circular ring shape when viewed from the axial direction. The plurality of busbars 224a are screwed to the busbar holder. Busbars 224a may be fixed by press fitting, snap fitting, insert molding, or the like.

[0019] Bus bar assembly 224 is located on the rear side of stator 23. Bus bar assembly 224 is inserted into first accommodating recess 211a of motor housing 211 from the rear side. One end of bus bar 224a is connected to coil wire 23d extending from coil 23c to the rear side. Bus bar 224a extends from the connection position with coil wire 23d toward board housing 213. The other end of bus bar 224a is connected to joint bus bar 251 at an end of bus bar assembly 224.

[0020] Busbar cover 225 is located on the rear side of busbar assembly 224. Busbar cover 225 is inserted into first accommodating recess 211a from the rear side. Busbar cover 225 has a circular ring shape when viewed in the axial direction. Busbar cover 225 covers busbar assembly 224 from the rear side. Motor cover 226 is placed over busbar cover 225 from the rear side. Motor cover 226 closes first accommodating recess 211a from the rear side.

[0021] Busbar cover 225 has step portion 225a at the outer circumferential end of the surface facing the rear side. Step portion 225a has a surface facing the rear side and a surface facing radially outward. Elastic member 225b made of an O-ring is disposed inside step portion 225a. Elastic member 225b is sandwiched in the axial direction between motor cover 226 and busbar cover 225. Motor cover 226 presses busbar cover 225 toward the front side via elastic member 225b.

[0022] The motor cover 226 is a disk-shaped member that covers the bus bar cover 225 from the rear side. The motor cover 226 has a cylindrical portion 226a extending along the central axis J, and an annular cover body 226b that spreads radially outward from the outer circumferential surface of the cylindrical portion 226a. The cylindrical portion 226a opens on both sides in the axial direction of the motor cover 226. The first bearing 27 is inserted from the front side into the opening on the front side of the cylindrical portion 226a. The first bearing 27 is supported by a bearing holder 226c located inside the cylindrical portion 226a.

[0023] Motor cover 226 extends radially outward of bus bar cover 225. Motor cover 226 is screwed to motor housing 211 at a location positioned radially outward of bus bar cover 225.

[0024] A breather 60 is attached to the rear end of the cylindrical portion 226a. A filter is built into the breather 60. The filter of the breather 60 is, for example, a gas-liquid separation filter that allows gas to pass but blocks liquid.

[0025] 1, the second bearing 28 is inserted from the rear side into the first through hole 210a that connects the first accommodating recess 211a and the second accommodating recess 212a. Inside the first through hole 210a, the oil seal 15, the fixing ring 16, the wave washer 17, and the second bearing 28 are arranged in this order from the front side.

[0026] The shaft 21 is passed through the inner holes of the second bearing 28, the wave washer 17, the fixing ring 16, and the oil seal 15. A pump mechanism 30 is connected to the front end of the shaft 21.

[0027] FIG. 2 is an enlarged partial cross-sectional view showing the periphery of the pump mechanism 30. As shown in FIG. The pump mechanism 30 has an inner rotor 31 connected to the front end of the shaft 21, and an outer rotor 32 located radially outward of the inner rotor 31. The pump mechanism 30 of this embodiment is, for example, a trochoid pump. The inner rotor 31 and the outer rotor 32 are pump gears and mesh with each other. The inner rotor 31 and the outer rotor 32 each have a trochoid tooth profile. The motor 220 rotates the inner rotor 31 to drive the pump mechanism 30.

[0028] The pump mechanism 30 is accommodated in the second accommodating recess 212a. That is, the pump housing 212 has the second accommodating recess 212a as a pump accommodating portion that accommodates the pump mechanism 30. The second accommodating recess 212a is a circular recess when viewed from the front side. The pump cover 212b covers the pump mechanism 30 accommodated in the second accommodating recess 212a from the front side.

[0029] The pump cover 212b extends radially outward beyond the second accommodating recess 212a. The pump cover 212b is fastened to an end surface of the pump housing 212 facing the front side at a position radially outer than the second accommodating recess 212a using a plurality of screws 215. An annular elastic member 214 is disposed on the end surface of the pump housing 212 facing the front side, surrounding the opening of the second accommodating recess 212a from the radially outer side. The connecting surface between the pump housing 212 and the pump cover 212b is sealed by the elastic member 214.

[0030] The pump housing 212 has a port installation surface 212c facing the front side at the rear end of the second accommodating recess 212a. The port installation surface 212c faces the pump mechanism 30 in the axial direction. 2 and 3, the pump housing 212 has an intake port 71 and an exhaust port 72 recessed from a port installation surface 212c toward the rear. The intake port 71 and the exhaust port 72 are arc-shaped grooves extending circumferentially when viewed in the axial direction. An intake side flow passage 81 opens to a surface 71a located on the outer periphery of the intake port 71 and facing inward in the radial direction. An exhaust side flow passage 82 opens to a surface 72a located on the outer periphery of the exhaust port 72 and facing inward in the radial direction.

[0031] 4 and 5, the suction side flow passage 81 has a first suction flow passage 81a extending radially outward from a connection position with the suction port 71, a second suction flow passage 81b extending from a radially outer end of the first suction flow passage 81a to the rear side, and a third suction flow passage 81c extending radially outward from a rear side end of the second suction flow passage 81b. The radially outer end of the third suction flow passage 81c is connected to the suction port 51 opening on the outer circumferential surface of the pump housing 212. That is, the suction side flow passage 81 is a flow passage that connects the suction port 51 opening on the surface facing radially outward of the pump housing 212 to the second accommodating recess 212a.

[0032] A cap 85 is fitted onto the intersection of the first intake passage 81a and the second intake passage 81b from the outer circumferential surface of the pump housing 212. A cap 86 is fitted onto the front end of the second intake passage 81b from the front end surface of the pump housing 212. The caps 85 and 86 close the openings of the drilled holes that form the first intake passage 81a and the second intake passage 81b. The passage extending from the intersection of the first intake passage 81a and the second intake passage 81b to the cap 86 is a hole formed in the process of forming the second intake passage 81b by drilling, and is not an essential part of the intake side passage 81 in terms of its function as a passage.

[0033] 5, the pump housing 212 has a through hole 73 that connects the space that accommodates the oil seal 15 to the suction port 71. The through hole 73 is a flow path that discharges oil that accumulates on the front side of the oil seal 15 to the suction port 71.

[0034] 4 and 6, the discharge-side flow passage 82 has a first discharge flow passage 82a that extends radially from a connection position with the discharge port 72 toward the outer periphery. An outer periphery end of the first discharge flow passage 82a is connected to a discharge port 52 that opens into the outer periphery of the pump housing 212. The discharge-side flow passage 82 has a branch flow passage 82b that branches off from the first discharge flow passage 82a and extends toward the rear side. A rear end of the branch flow passage 82b reaches the rear end of the pump body 210.

[0035] A relief valve 95 is disposed in the branch flow passage 82b. The relief valve 95 has a valve body 95a that is movable along the axial direction, a coil spring 95b that pushes the valve body 95a toward the front side, and a fixed portion 95c that supports the rear end of the coil spring 95b. The fixed portion 95c has a male thread and is screwed into the rear end of the branch flow passage 82b. The fixed portion 95c closes the opening at the rear end of the branch flow passage 82b.

[0036] As shown in Fig. 7, the discharge-side flow path 82 has a discharge flow path 82c extending downward from the branch flow path 82b. The discharge flow path 82c branches off from a region in the branch flow path 82b where the valve body 95a moves back and forth in the axial direction. The end of the discharge flow path 82c on the lower side in the figure is connected to the suction-side flow path 81. In this embodiment, the discharge flow path 82c is connected to a position where the second suction flow path 81b and the third suction flow path 81c intersect.

[0037] The relief valve 95 operates according to the pressure in the discharge-side flow path 82. When the valve body 95a retreats to the rear side by a predetermined distance or more due to the oil pressure, the branch flow path 82b and the discharge flow path 82c are connected, and a portion of the oil in the discharge-side flow path 82 is returned to the suction-side flow path 81. This makes it possible to maintain the discharge pressure of the electric oil pump 200 below the limit value. Furthermore, by installing the relief valve 95, damage to piping and equipment due to abnormal pressure can be suppressed.

[0038] In this embodiment, the pump housing 212 is a portion of the electric oil pump 200 that has a second accommodating recess 212a (pump accommodating portion) that accommodates the pump mechanism 30, an intake port 71 and an exhaust port 72 connected to the second accommodating recess 212a, an intake port 51 connected to the intake port 71 via an intake side flow path 81, and an exhaust port 52 connected to the exhaust port 72 via the discharge side flow path 82. In this embodiment, flow paths 81b, 81c, 82b, and 82c, suction port 51, and discharge port 52 are provided in a portion of pump body 210 that is located radially outward from motor 220. The portion in which these flow paths, suction port, and discharge port are provided is included in pump housing 212 in this embodiment. That is, pump housing 212 in this embodiment is located on the front side and radially outward from motor 220.

[0039] In electric oil pump 200 having the above configuration, as shown in Figs. 2 and 6, suction port 51 and discharge port 52 are located axially closer to motor 220 than second accommodating recess 212a (pump accommodating portion). According to this configuration, the main parts of the electric oil pump 200 can be accommodated within the range of the axial length from the motor 220 to the pump mechanism 30. Therefore, it is possible to provide an electric oil pump that is smaller in size in the axial direction than a configuration having an intake port or a discharge port on the pump cover 212b side. In this embodiment, the suction port 51, the discharge port 52, the suction flow path 81, and the discharge flow path 82 are provided inside the pump housing 212. Therefore, the oil flow paths can be formed all at once when machining the pump housing 212. Therefore, the electric oil pump 200 can be manufactured efficiently and at low cost.

[0040] 5, in this embodiment, the intake port 51 is located on the radially outer side of the motor 220. With this configuration, the second intake passage 81b and the third intake passage 81c connected to the intake port 51 pass through the radially outer side of the motor 220. That is, the oil passes near the stator 23, which is a heat source of the motor 220. This makes it easier for the oil to cool the stator 23. In this embodiment, only the suction port 51 is located on the radially outer side of the motor 220, but the discharge port 52 may be located on the radially outer side of the motor 220. Alternatively, both the suction port 51 and the discharge port 52 may be located on the radially outer side of the motor 220.

[0041] In this embodiment, the pump housing 212 has a port installation surface 212c axially facing the pump mechanism 30, and a suction port 71 and a discharge port 72 recessed from the port installation surface 212c to the opposite side to the pump mechanism 30, at an end of the second accommodating recess 212a on the motor 220 side (rear side). A suction side flow path 81 is connected to the suction port 71. A discharge side flow path 82 is connected to the discharge port 72. According to this configuration, since the suction port 71 and the discharge port 72 are disposed on the motor 220 side of the pump mechanism 30, the electric oil pump 200 is less likely to become large in the axial direction. Since the oil passes close to the motor 220, which is a heat source, the motor 220 is easily cooled by the oil.

[0042] In this embodiment, the suction side flow passage 81 opens to a surface facing in the radial direction of the suction port 71. The discharge side flow passage 82 opens to a surface facing in the radial direction of the discharge port 72. With this configuration, the flow passages extend in the radial direction from the suction port 71 and the discharge port 72, so that the flow passage located between the pump mechanism 30 and the motor 220 can be made small in the axial direction. This makes it even more difficult for the electric oil pump 200 to become large in the axial direction.

[0043] 2 and 3, in this embodiment, the surface of the suction port 71 facing radially outward is an inclined surface 71b inclined with respect to the central axis, and the surface of the discharge port 72 facing radially outward is an inclined surface 72b inclined with respect to the central axis. With this configuration, it is easier to reduce the radial width of suction port 71 and the radial width of discharge port 72 compared to a case where the radially outward surface of suction port 71 and the radially outward surface of discharge port 72 are surfaces that extend straight along the axial direction. Therefore, it is easier to arrange the components of electric oil pump 200 in positions that overlap suction port 71 and discharge port 72 when viewed from the radial direction. This makes it easier to make electric oil pump 200 smaller in size in the axial direction.

[0044] In this embodiment, both the suction port 71 and the discharge port 72 are configured to have inclined surfaces 71b, 72b, but either one of the suction port 71 and the discharge port 72 may be configured to have an inclined surface that is inclined with respect to the axial direction. In this embodiment, both of the inclined surfaces 71b and 72b face radially outward in the port, but a configuration in which a surface facing radially inward in the port is an inclined surface may be used. Alternatively, a configuration in which at least one of the suction port 71 and the discharge port 72 has both a surface facing radially outward and a surface facing radially inward be an inclined surface may be used.

[0045] 2, the oil seal 15 is disposed radially inside the inclined surfaces 71b, 72b. That is, at least one of the components disposed around the shaft 21 is disposed at a position overlapping with the inclined surfaces 71b, 72b when viewed from the radial direction. According to this configuration, the suction port 71 and the discharge port 72 are arranged in the radial direction while maintaining a distance from the members around the shaft 21, so that the pump mechanism 30 and the motor 220 can be shortened in the axial direction while maintaining the strength of the pump housing 212, resulting in a compact design. Since the length of the shaft 21 from the motor 220 to the pump mechanism 30 can be shortened, the vibration of the pump mechanism 30 is reduced, the hydraulic pulsation of the pump is reduced, and vibration and noise can be reduced. The suction port 71 and the discharge port 72 are closer to the motor 220, which is a heat generating factor, so the heat dissipation effect is improved. This allows for a smaller size and higher output.

[0046] Furthermore, the second bearing 28 may be disposed radially inward of the inclined surfaces 71b, 72b. With this configuration, the second bearing 28 is disposed close to the pump mechanism 30, and the distance from the second bearing 28 to the inner rotor 31 is shortened. This reduces the runout of the shaft 21 at the position of the inner rotor 31, and reduces hydraulic pulsation of the pump. The vibration and noise of the electric oil pump 200 can be reduced.

[0047] In this embodiment, pump cover 212b has a suction side cover recess 91 recessed toward the front side from a surface facing the rear side opposite pump mechanism 30, and a discharge side cover recess 92. The suction side cover recess 91 faces the suction port 71 in the axial direction. The suction side cover recess 91 has a planar shape that generally corresponds to the suction port 71 when viewed in the axial direction. The discharge side cover recess 92 has a planar shape that generally corresponds to the discharge port 72 when viewed in the axial direction.

[0048] The suction side cover recess 91 and the discharge side cover recess 92 may be provided as necessary. That is, the pump cover 212b may be configured without the suction side cover recess 91 and the discharge side cover recess 92.

[0049] As shown in FIG. 1, the board unit 240 includes a control board 40, a board cover 241 that covers the control board 40 from the radially outer side, and a bus bar unit 250 that is fixed to the control board 40.

[0050] The board cover 241 is a box-shaped member that opens toward the board housing 213 side (+Z side). The control board 40 is fixed to an opening of the board cover 241 that faces upward in the figure. In this embodiment, the board cover 241 is made of resin. The board cover 241 has a connector 241b in which multiple metal terminals 241a are insert-molded.

[0051] The busbar unit 250 is fixed to an end portion on the rear side of the control board 40. The busbar unit 250 connects the motor 220 and the control board 40. The busbar unit 250 is accommodated inside the second through-hole 210b that connects the third accommodating recess 213a and the first accommodating recess 211a.

[0052] Bus bar unit 250 has a plurality of joint bus bars 251 and a joint bus bar holder 252 that supports the plurality of joint bus bars 251. One ends of the plurality of joint bus bars 251 extend from joint bus bar holder 252 toward motor 220, and are electrically connected to bus bar 224a. The other ends of the plurality of joint bus bars 251 are connected to control board 40. The control board 40 and motor 220 are electrically connected via bus bar unit 250.

[0053] The board unit 240 is fixed to the board housing 213 of the pump body 210 with the control board 40 facing the motor 220. In the case of this embodiment, a board cover 241 of the board unit 240 is screwed to the board housing 213. The control board 40 is enclosed between the pump body 210 and the board cover 241.

[0054] Within the scope of the present invention, the configurations (elements) described in the above-mentioned embodiments, variants, and notes may be combined, and addition, omission, substitution, and other modifications of the configurations are possible.

[0055] [Second embodiment] An electric oil pump will be described below as one embodiment of the electric pump. An electric oil pump according to one embodiment is used to supply oil (fluid) to equipment mounted on a vehicle or the like.

[0056] In each of the drawings referred to below, an XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system as appropriate. In the XYZ coordinate system, the X-axis direction is parallel to the axis of the central axis J shown in Fig. 1. The central axis J is the central axis of a shaft 21 of a motor 220 described later. The Y-axis direction is a direction perpendicular to the X-axis and parallel to the depth direction in Fig. 1. The Z-axis direction is a direction perpendicular to both the X-axis and Y-axis directions and parallel to the up-down direction in Fig. 1. In each of the X-axis, Y-axis, and Z-axis directions, the side toward which the arrow in the figure points is the + side, and the opposite side is the - side.

[0057] In the following description, unless otherwise specified, the direction parallel to the central axis J (X-axis direction) will be simply referred to as the "axial direction." The radial direction centered on the central axis J will be simply referred to as the "radial direction." The circumferential direction centered on the central axis J, i.e., around the axis of the central axis J (θ direction), will be simply referred to as the "circumferential direction."

[0058] Also, the positive side (+X side) in the X-axis direction may be referred to as the "front side". Similarly, the negative side (-X side) in the X-axis direction may be referred to as the "rear side". The front side (+X side) corresponds to one axial side in the present invention. The rear side (-X side) corresponds to the other axial side in the present invention.

[0059] As shown in FIG. 1, the electric oil pump (electric pump) 300 includes a pump body 210, a motor 220, a pump mechanism 30, and a control board . The pump body 210 has a motor housing 211 that houses the motor 220, a pump housing 212 that houses the pump mechanism 30, and a board housing 213 that houses the control board 40. In this embodiment, the motor housing 211, the pump housing 212, and the board housing 213 are part of a single member.

[0060] The motor housing 211 is located on the rear side (-X side) of the pump body 210. The motor housing 211 is cylindrical and extends in the axial direction. The motor housing 211 has a first accommodating recess 211a that is a recess that opens to the rear side. The first accommodating recess 211a is closed from the rear side by a motor cover 226, which will be described later.

[0061] The pump housing 212 is located on the front side (+X side) of the pump body 210. The pump housing 212 has a second accommodating recess (pump accommodating portion) 212a consisting of a recess that opens to the front side. The pump mechanism 30 is accommodated in the second accommodating recess 212a. The electric oil pump 300 has a pump cover 212b that closes the second accommodating recess 212a from the front side.

[0062] The board housing 213 is located on a side surface of the motor housing 211 and the pump housing 212. The board housing 213 is located on the illustrated lower side (-Z side) of the motor housing 211 and the pump housing 212. The board housing 213 has a generally rectangular shape when viewed from the radial outside. The board housing 213 has a third accommodating recess 213a that opens toward the illustrated lower side of the pump body 210. A board unit 240, which will be described later, is attached to the board housing 213 from the illustrated lower side.

[0063] The pump body 210 has a first through hole 210a that axially connects the first accommodating recess 211a of the motor housing 211 and the second accommodating recess 212a of the pump housing 212. The pump body 210 has a second through hole 210b that radially connects the first accommodating recess 211a and the third accommodating recess 213a of the board housing 213.

[0064] The motor 220 includes a rotor 22 having a shaft 21, a stator 23, a bus bar assembly 224, a bus bar cover 225, a motor cover 226, a first bearing 27 (bearing) and a second bearing (bearing) 28. In this embodiment, the first bearing 27 and the second bearing 28 are rolling bearings. Either or both of the first bearing 27 and the second bearing 28 may be a sliding bearing. A front end of the shaft 21 is connected to the pump mechanism 30.

[0065] Busbar assembly 224 has a plurality of busbars 224a and a resin busbar holder that holds the plurality of busbars 224a. Busbar assembly 224 has a circular ring shape when viewed from the axial direction. The plurality of busbars 224a are screwed to the busbar holder. Busbars 224a may be fixed by press fitting, snap fitting, insert molding, or the like.

[0066] Bus bar assembly 224 is located on the rear side of stator 23. Bus bar assembly 224 is inserted into first accommodating recess 211a of motor housing 211 from the rear side. One end of bus bar 224a is connected to coil wire 23d extending from coil 23c to the rear side. Bus bar 224a extends from the connection position with coil wire 23d toward board housing 213. The other end of bus bar 224a is connected to joint bus bar 251 at an end of bus bar assembly 224.

[0067] Busbar cover 225 is located on the rear side of busbar assembly 224. Busbar cover 225 is inserted into first accommodating recess 211a from the rear side. Busbar cover 225 has a circular ring shape when viewed in the axial direction. Busbar cover 225 covers busbar assembly 224 from the rear side. Motor cover 226 is placed over busbar cover 225 from the rear side. Motor cover 226 closes first accommodating recess 211a from the rear side.

[0068] Busbar cover 225 has step portion 225a at the outer circumferential end of the surface facing the rear side. Step portion 225a has a surface facing the rear side and a surface facing radially outward. Elastic member 225b made of an O-ring is disposed inside step portion 225a. Elastic member 225b is sandwiched in the axial direction between motor cover 226 and busbar cover 225. Motor cover 226 presses busbar cover 225 toward the front side via elastic member 225b.

[0069] The motor cover 226 is a disk-shaped member that covers the bus bar cover 225 from the rear side. The motor cover 226 has a cylindrical portion 226a extending along the central axis J, and an annular cover body 226b that spreads radially outward from the outer circumferential surface of the cylindrical portion 226a. The cylindrical portion 226a opens on both sides in the axial direction of the motor cover 226. The first bearing 27 is inserted from the front side into the opening on the front side of the cylindrical portion 226a. The first bearing 27 is supported by a bearing holder 226c located inside the cylindrical portion 226a.

[0070] Motor cover 226 extends radially outward of bus bar cover 225. Motor cover 226 is screwed to motor housing 211 at a location positioned radially outward of bus bar cover 225.

[0071] A breather 60 is attached to the rear end of the cylindrical portion 226a. A filter is built into the breather 60. The filter of the breather 60 is, for example, a gas-liquid separation filter that allows gas to pass but blocks liquid.

[0072] 1, the second bearing 28 is inserted from the rear side into the first through hole 210a that connects the first accommodating recess 211a and the second accommodating recess 212a. Inside the first through hole 210a, the oil seal 15, the fixing ring 16, the wave washer 17, and the second bearing 28 are arranged in this order from the front side.

[0073] The shaft 21 is passed through the inner holes of the second bearing 28, the wave washer 17, the fixing ring 16, and the oil seal 15. A pump mechanism 30 is connected to the front end of the shaft 21.

[0074] As shown in FIG. 2, the pump mechanism 30 has an inner rotor 31 connected to the front end of the shaft 21, and an outer rotor 32 located radially outward of the inner rotor 31. The pump mechanism 30 of this embodiment is, for example, a trochoid pump. The inner rotor 31 and the outer rotor 32 are pump gears and mesh with each other. The inner rotor 31 and the outer rotor 32 each have a trochoid tooth profile. The motor 220 rotates the inner rotor 31 to drive the pump mechanism 30.

[0075] The pump mechanism 30 is accommodated in the second accommodating recess 212a. That is, the pump housing 212 has the second accommodating recess 212a as a pump accommodating portion that accommodates the pump mechanism 30. The second accommodating recess 212a is a circular recess when viewed from the front side. The pump cover 212b covers the pump mechanism 30 accommodated in the second accommodating recess 212a from the front side.

[0076] The pump cover 212b extends radially outward beyond the second accommodating recess 212a. The pump cover 212b is fastened to an end surface of the pump housing 212 facing the front side at a position radially outer than the second accommodating recess 212a using a plurality of screws 215. An annular elastic member 214 is disposed on the end surface of the pump housing 212 facing the front side, surrounding the opening of the second accommodating recess 212a from the radially outer side. The connecting surface between the pump housing 212 and the pump cover 212b is sealed by the elastic member 214.

[0077] The pump housing 212 has a port installation surface 212c facing the front side at the rear end of the second accommodating recess 212a. The port installation surface 212c faces the pump mechanism 30 in the axial direction. 2 and 3, the pump housing 212 has an intake port 71 and an exhaust port 72 recessed from a port installation surface 212c toward the rear. The intake port 71 and the exhaust port 72 are arc-shaped grooves extending circumferentially when viewed in the axial direction. An intake side flow passage 81 opens to a surface 71a located on the outer periphery of the intake port 71 and facing inward in the radial direction. An exhaust side flow passage 82 opens to a surface 72a located on the outer periphery of the exhaust port 72 and facing inward in the radial direction.

[0078] 4 and 8, the suction side flow passage 81 has a first suction flow passage 81a extending radially outward from a connection position with the suction port 71, a second suction flow passage (relief flow passage) 81b extending from a radially outer end of the first suction flow passage 81a to the rear side, and a third suction flow passage 81c extending radially outward from a rear side end of the second suction flow passage 81b. The radially outer end of the third suction flow passage 81c is connected to the suction port 51 opening on the outer circumferential surface of the pump housing 212. That is, the suction side flow passage 81 is a flow passage that connects the suction port 51 opening on the surface facing radially outward of the pump housing 212 to the second accommodating recess 212a.

[0079] A cap 85 is fitted onto the intersection of the first intake passage 81a and the second intake passage 81b from the outer circumferential surface of the pump housing 212. A cap 86 is fitted onto the front end of the second intake passage 81b from the front end surface of the pump housing 212. The caps 85 and 86 close the openings of the drilled holes that form the first intake passages 81a and 81b. The passage extending from the intersection of the first intake passage 81a and the second intake passage 81b to the cap 86 is a hole formed in the process of forming the second intake passage 81b by drilling, and is not an essential part of the intake side passage 81 in terms of its function as a passage.

[0080] 8, the pump housing 212 has a through hole 73 that connects the space that accommodates the oil seal 15 to the suction port 71. The through hole 73 is a flow path that discharges oil that accumulates on the front side of the oil seal 15 to the suction port 71.

[0081] As shown in FIG. 4 and FIG. 9, the discharge-side flow passage 82 has a first discharge flow passage 82a extending radially outward from the discharge port 72 side to the discharge port 52 side. An outer peripheral end of the first discharge flow passage 82a is connected to the discharge port 52 that opens on the outer peripheral surface of the pump housing 212. The discharge-side flow passage 82 has a branch flow passage (relief flow passage) 82b branching from the first discharge flow passage 82a and extending toward the rear side along the central axis J. An end of the branch flow passage 82b on the rear side reaches an end of the rear side of the pump body 210. Here, "along the central axis J" may mean that the distance between the central axis J and the branch flow passage (relief flow passage) 82b varies along the axial direction. For example, the branch flow passage (relief flow passage) 82b may be inclined with respect to the central axis J on a plane formed by the X-axis direction and the Z-axis direction.

[0082] A relief valve 95 that operates in response to the pressure of the fluid in the discharge-side flow path 82, as shown in FIGS. The relief valve 95 has a valve body 95a that is movable along the axial direction, a coil spring 95b that pushes the valve body 95a toward the front side, and a fixed part 95c that supports the rear end of the coil spring 95b. The fixed part 95c has a male thread and is screwed into the rear end of the branch flow passage 82b as shown in Figures 9 and 10. The fixed part 95c closes the opening at the rear end of the branch flow passage 82b.

[0083] As shown in Fig. 10, the valve body 95a has a pair of first and second annular grooves 96b and 96c that open to the outer circumferential surface at a portion located on the front side, and has an accommodating recess 96d for holding a coil spring 95b at a portion located on the rear side. The first and second annular grooves 96b and 96c are annular grooves that are recessed radially inward from the outer circumferential surface of the valve body 95a and are formed around the entire axis of the valve body 95a. The first and second annular grooves 96b and 96c create a gap between the inner wall surface of the branch flow passage 82b in which the relief valve 95 is arranged.

[0084] The first annular groove 96b and the second annular groove 96c are positioned at a predetermined distance from each other in the longitudinal direction of the valve body 95a, and a sealing portion 99 is present between them. The diameter of the sealing portion 99 is approximately equal to the diameter of the portion of the branch flow path 82b where the valve body 95a is disposed. The sealing portion 99 has a diameter such that its outer circumferential surface is approximately in contact with the inner wall surface of the branch flow path 82b, and is therefore capable of sealing between the branch flow path 82b and a discharge flow path 82c, which will be described later.

[0085] The valve body 95a has a first central hole 97a and a second central hole 97b extending along the length direction at the center when viewed from the axial direction. The first central hole 97a and the second central hole 97b are separated in the length direction by the sealing portion 99.

[0086] The valve body 95a has four through holes that penetrate the valve body 95a in the radial direction. Specifically, the four through holes are a pair of first through holes 98a and a pair of second through holes 98b. Each of the first through holes 98a overlaps with the first annular groove 96b when viewed in the radial direction. Each of the first through holes 98a opens into the first annular groove 96b. Meanwhile, each of the second through holes 98b coincides with the second annular groove 96c in the axial direction and opens into the second annular groove 96c.

[0087] The pair of first through holes 98a are through holes extending in radial directions perpendicular to each other. The pair of first through holes 98a are connected to the rear side portion of the first center hole 97a at the position where they intersect with each other. That is, one end side of the first center hole 97a opens at the center of the front end face, and the other end side opens at the position where the pair of first through holes 98a intersect with each other. As a result, the first center hole 97a of the valve body 95a accommodated in the branch flow path 82b and the pair of first through holes 98a are connected to the first discharge flow path 82a connected to the pump mechanism 30.

[0088] The pair of second through holes 98b are through holes extending in a radial direction perpendicular to each other. The pair of second through holes 98b are connected to the front side portion of the second center hole 97b at the position where they intersect with each other. That is, one end side of the second center hole 97b opens at the position where the pair of second through holes 98b intersect with each other, and the other end side opens to the accommodation recess 96d. As a result, the second center hole 97b and the second through hole 98b of the valve body 95a are connected to the exhaust flow passage 82c side described later.

[0089] The branch flow passage 82b in which the relief valve 95 is housed has an inner diameter that gradually increases from the front side to the rear side. The branch flow passage 82b has a first hole 821 connected to the first discharge flow passage 82a, a second hole 822 connected to the rear side of the first hole 821, and a screw hole 823 connected to the rear side of the second hole 822. Of the relief valve 95, the valve body 95a is housed in the second hole 822. The fixing portion 95c of the relief valve 95 has a male thread portion on its outer circumferential surface, and is fixed by being screwed into the female thread portion of the screw hole 823.

[0090] The valve body 95a, which is pushed toward the front side by the force of the coil spring 95b, stops when its tip hits the step portion 824 between the first hole 821 and the second hole 822. The valve body 95a has a length shorter than the second hole 822. Therefore, when the valve body 95a hits the step portion 824, there is a gap in the axial direction between the valve body 95a and the fixing portion 95c fitted into the screw hole 823, and this gap allows the valve body 95a to move backward toward the rear side.

[0091] As shown in FIG. 10, the discharge-side flow path 82 further includes a discharge flow path 82c that extends from the branch flow path 82b in a direction intersecting the axial direction and toward the lower side in the figure.

[0092] The discharge flow passage 82c branches off from a region in the branch flow passage 82b where the valve body 95a advances and retreats in the axial direction, and extends in a direction intersecting the central axis J. One end of the discharge flow passage 82c is connected to a second hole 822 of the branch flow passage 82b in which the valve body 95a is accommodated. The other end of the discharge flow passage 82c, which is on the lower side in the figure, is connected to the connection flow passage 82d.

[0093] The connection flow path 82d connects the exhaust flow path 82c to the intake side flow path 81. Specifically, the connection flow path 82d is connected to the intake side flow path 81 at a position where the third intake flow path 81c connected to the intake port 51 and the second intake flow path 81b intersect.

[0094] The second intake passage 81b is a passage that is parallel to the branch passage 82b and extends in the axial direction from the connection position with the connection passage 82d toward the front side.

[0095] In this embodiment, a flow path constituted by the branch flow path 82b, the discharge flow path 82c, and the connection flow path 82d, which are connected to each other, is defined as a "relief flow path" in this embodiment. The relief flow path 80 is a flow path that returns a part of the fluid discharged from the pump mechanism 30 to the suction side flow path 81. At least a part of the relief flow path 80 is disposed radially outside the motor 220. In this embodiment, the branch flow path 82b, the discharge flow path 82c, and the connection flow path 82d that constitute the relief flow path 80 are each disposed radially outside the motor 220. It is preferable that "at least a part of the relief flow passage 80" disposed on the radially outer side of the motor 220 is the "branch flow passage 82b." In other words, it is preferable that at least the branch flow passage 82b of the relief flow passage 80 extending along the central axis J of the motor 220 is disposed on the radially outer side.

[0096] A relief valve 95 disposed in the branch passage 82b operates based on the pressure in the first discharge passage 82a. When the pressure of the oil discharged into the first discharge flow passage 82a has not reached the relief pressure, i.e., when the pressure has not reached the pressure at which the relief valve 95 operates, the valve body 95a of the relief valve 95 is pushed forward by the coil spring 95b and abuts against the step portion 824 of the branch flow passage 82b. At this time, the sealing portion 99 of the valve body 95a is positioned inside the second hole 822, so that the rear side of the branch flow passage 82b is blocked and the branch flow passage 82b and the discharge flow passage 82c are separated from each other.

[0097] When the valve body 95a retreats to the rear side by a predetermined length or more due to the oil pressure, the branch flow path 82b and the discharge flow path 82c are connected, and a part of the oil in the discharge-side flow path 82 is returned to the suction-side flow path 81. That is, when the valve body 95a retreats to the rear side and the part of the first annular groove 96b advances to a connecting position with the discharge flow path 82c, the first discharge flow path 82a and the discharge flow path 82c are connected through the first center hole 97a and the pair of first annular grooves 96b. A part of the oil that has flowed from the first discharge flow path 82a into the branch flow path 82b is discharged to the discharge flow path 82c through the first center hole 97a of the valve body 95a, the pair of first through holes 98a, and the pair of first annular grooves 96b, and flows into the second intake flow path 81b through the connecting flow path 82d, thereby further relieving the excess oil pressure.

[0098] The oil discharged through the relief passage 80 and the oil sucked through the suction port 51 are mixed in the second suction passage 81b and are guided to the first suction passage 81a which communicates with the pump mechanism 30.

[0099] This allows the discharge pressure of the electric oil pump 300 to be maintained at or below the limit value. Also, by providing the relief valve 95 in the relief flow passage 80, a portion of the discharged oil flows into the relief flow passage 80 and then into the suction side flow passage 81, so that damage to piping and equipment due to abnormal pressure can be more effectively suppressed. In this way, the oil discharged from the pump mechanism 30 flows into the relief valve 95 side through the branch flow passage 82b, so that the oil pressure can be relieved and the load on the pump mechanism 30 can be reduced.

[0100] When the oil pressure discharged into the first discharge flow passage 82a reaches the relief pressure and the relief valve 95 operates (moves) to relieve the oil into the branch flow passage 82b, the pump mechanism 30 is subjected to high pressure, which increases the load on the pump mechanism 30, and the current flowing through the motor 220 increases, resulting in increased heat generation by the motor 220. According to the configuration of this embodiment, the relief flow passage 80 is disposed radially outside the motor 220, which is a heat source. Therefore, even if the load on the pump mechanism 30 increases when the relief pressure is reached, the oil discharged from the stator 23 side flows through the relief flow passage 80, thereby dissipating heat from the motor 220. In this embodiment, the relief flow passage 80 is present radially outside the motor 220 over the entire axial direction, so that the heat dissipation effect against the heat generated by the motor 220 can be more effectively obtained.

[0101] Furthermore, as described above, if at least the branch passage 82b of the relief passage 80 close to the first discharge passage 82a is disposed radially outward of the motor 220, the heat of the motor 220 can be dissipated at an early stage when the load of the pump mechanism 30 becomes high, that is, at an early stage when the heat of the motor 220 starts to increase. In this way, since the heat of the motor 220 can be dissipated at an early stage when the heat of the motor 220 starts to increase, the temperatures of the stator 23 having the coil 23c, the first bearing 27, the second bearing 28, the board unit 240, the rotor 22 having the shaft 21, etc. do not become too high, and adverse effects due to high heat can be suppressed. The quality reliability of the electric oil pump 300 can be improved.

[0102] In addition, at least a portion of each of the branch flow passages 82b, the exhaust flow passages 82c, and the connecting flow passages 82d of the relief flow passage 80 are arranged radially outside the motor 220, so that each flow passage is located at a different position circumferentially of the motor 220, thereby enhancing the heat dissipation effect of the motor 220.

[0103] In this manner, in this embodiment, even if there is an increase in the load on the pump mechanism 30 that occurs when the relief pressure is reached, the oil flows along the side of the motor 220, thereby providing two effects: the oil pressure is relieved, and at the same time, the motor 220 that has become overheated can be effectively cooled. Because the motor 220 is excellent at dissipating heat, it is possible to prevent the efficiency of the motor 220 and the pump mechanism 30 from decreasing.

[0104] Furthermore, in this embodiment, since the motor housing 211 and the pump housing 212 having the relief passage 80 are integrated, the heat dissipation effect of the motor 220 can be further improved.

[0105] (Modification) FIG. 11 is a partial cross-sectional view showing a modified example of the relief channel. The relief passage 90 shown in FIG. 11 has the branch passage 82b and the exhaust passage 82c described above, and a connection passage 82d extending long along the axial direction of the motor 220, on the radial outside of the motor 220. In this example, the intake port 51 is located closer to the pump mechanism 30 than the motor 220 in the axial direction, and the exhaust passage 82c is located away from the intake port 51 toward the rear side. Therefore, the connection passage 82d extends long along the axial direction compared to the above-mentioned embodiment. As shown in FIG. 11, for example, the connection passage 82d extends over a length of more than half the axial length of the motor 220, and the entirety of the connection passage 82d is located radially outside the motor 220.

[0106] Since the connecting passage 82d extends a long way toward the rear side, as the oil discharged from the pump mechanism 30 flows through the connecting passage 82d, the pulsating component of the oil caused by the pump mechanism 30 is mitigated, thereby suppressing the discharge pulsation of the oil discharged from the pump mechanism 30.

[0107] In this way, in this example, since not only the branch flow passages but also the connection flow passage 82d extend long along the axial direction on the radial outside of the motor 220, heat from the motor 220 can be dissipated at different positions in the circumferential direction of the motor 220. Such a relief flow passage 90 can suppress oil discharge pulsation and can cool the entire motor 220 more efficiently.

[0108] Within the scope of the present invention, the configurations (elements) described in the above-mentioned embodiments, variants, and notes may be combined, and addition, omission, substitution, and other modifications of the configurations are possible.

[0109] For example, in the above embodiment, the motor housing 211 and the pump housing 212 are integral with each other, but they may be configured as separate bodies.

[0110] In addition, in the above embodiment, the suction port 51 and the discharge port 52 are located closer to the motor 220 than the pump mechanism 30 in the axial direction, but this is not limited to the above and can be modified as appropriate. [Explanation of symbols]

[0111] 15...oil seal, 21...shaft, 22...rotor, 30...pump mechanism, 31...inner rotor, 51...suction port, 52...discharge port, 71...suction port, 71a, 72a...surface facing radially inward, 71b, 72b...inclined surface, 72...discharge port, 81...suction side flow path, 82...discharge side flow path, 200, 300...electric oil pump (electric pump), 211...motor housing, 212...pump housing, 212a...second accommodating recess (pump accommodating portion), 212c...port installation surface, 220...motor, J...center axis

Claims

1. A motor having a rotor that can rotate around a central axis; a pump mechanism coupled to the motor; a motor housing that houses the motor; a pump housing that houses the pump mechanism, The pump housing comprises: a suction port and a discharge port that open to an outer peripheral surface of the pump housing; an intake side flow passage connecting the pump mechanism and the intake port; a discharge side flow path connecting the pump mechanism and the discharge port, The discharge side flow path is a first discharge flow passage extending radially outward from the pump mechanism side to the discharge port side; a branch flow path branching from the first discharge flow path and extending along the central axis; a discharge flow path extending from the branch flow path in a direction intersecting the central axis; a connection flow path connected from the exhaust flow path to the intake side flow path, a relief valve that operates in response to the pressure of the fluid in the discharge-side flow path is disposed in the branch flow path; the branch flow path, the discharge flow path, and the connection flow path form a relief flow path that returns a portion of the fluid discharged from the pump mechanism to the suction side flow path, An electric pump, wherein at least a portion of the relief passage is disposed radially outward of the motor.

2. The electric pump according to claim 1 , wherein at least a portion of the relief passage is the branch passage.

3. the pump mechanism is located on the other axial side of the motor, The branch flow passage extends from the other axial side to the one axial side, The connecting flow passage extends from one side to the other side in the axial direction. The electric pump according to claim 1 or 2.

4. The electric pump according to claim 1 , wherein at least a portion of each of the branch passage, the discharge passage, and the connection passage is disposed radially outward of the motor.

5. The electric pump according to claim 1 , wherein the motor housing and the pump housing are integral with each other.

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