Electric oil pump

Abstract

To highly efficiently lubricate a support bearing of an output shaft of a motor part in an electric oil pump.SOLUTION: An electric oil pump 1 comprises a housing 6 that houses a pump part 2 and a motor part 3. An output shaft 5 of the motor part 3 is freely rotatably supported with respect to the housing 6 by first and second rolling bearings 16 and 17. Due to rotation of the output shaft 5, an inner rotor 21 disposed at an end on one axial side of the output shaft 5 rotates in the pump chamber 6A, consequently oil is sucked and discharged, and the oil in the pump chamber 6A is supplied through an oil supply passage to the second rolling bearing 17. A second oil supply passage 32 for supplying the oil to the second rolling bearing 17 communicates a storage space of the second rolling bearing 17 in the motor chamber 6B and the pump chamber 6A with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electric oil pump used as a hydraulic supply source for supplying oil (hydraulic fluid) to hydraulic equipment mounted on a vehicle such as an automobile. [Background technology]

[0002] For example, Patent Document 1 listed below describes an electric oil pump in which a motor section having an electric motor and a pump section driven by the output of the motor section are arranged in series in the axial direction. In this electric oil pump, the output shaft of the electric motor is rotatably supported relative to the housing by two rolling bearings (first and second rolling bearings) arranged at an interval in the axial direction.

[0003] In order to ensure that the rolling bearings that support the output shaft maintain stable bearing performance over a long period of time, internal lubrication using a lubricant such as lubricating oil or grease is necessary. In the electric pump of Patent Document 1, drain oil leaked from the inside of the pump section (pump chamber) is used as a lubricant.

[0004] More specifically, the hollow output shaft of the electric motor is fitted onto the outer periphery of the input shaft of the pump unit, and the first rolling bearing, which is located relatively closer to the pump chamber, is supplied with the drain oil through an oil supply passage formed along the outer periphery of the input shaft of the pump unit, while the second rolling bearing, which is located relatively farther from the pump chamber (the axial opposite side of the first rolling bearing across the rotor), is supplied with drain oil that has passed through (lubricated) the first rolling bearing and then been introduced into the small radial gap formed between the rotor and stator of the electric motor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-136965 Summary of the Invention [Problem to be solved by the invention]

[0006] When the above-described bearing lubrication structure is adopted, drain oil can be supplied abundantly as a lubricant to the first rolling bearing located close to the pump chamber. However, because the drain oil that passes through the first rolling bearing is introduced into (the radial gap between) the rotor and stator of the electric motor, and into (the radial gap between) the output shaft of the electric motor and the input shaft of the pump unit, it is not possible to supply a sufficient amount of drain oil to the second rolling bearing, which may result in inadequate internal lubrication of the second rolling bearing.

[0007] Therefore, an object of the present invention is to provide a high-quality, long-life electric oil pump that can evenly lubricate two rolling bearings that rotatably support the output shaft of an electric motor on both axial sides of the rotor. [Means for solving the problem]

[0008] The present invention, which has been devised to achieve the above object, provides a hydraulic oil pump comprising: a pump section for sucking and discharging oil; a motor section for driving the pump section; and a housing that accommodates the pump section and the motor section in an axially aligned state, The output shaft of the motor unit is rotatably supported relative to the housing by first and second rolling bearings disposed on one and the other axial sides of a rotor connected to the outer periphery of the output shaft of the motor unit, An electric oil pump in which, as the output shaft rotates, a pump rotor provided at one axial end of the output shaft rotates within a pump chamber, thereby sucking in and discharging oil, and the oil within the pump chamber is supplied to first and second rolling bearings via an oil supply passage, The oil supply passage that supplies oil to the second rolling bearing is characterized in that it communicates between the pump chamber and the accommodation space for the second rolling bearing.

[0009] As described above, if oil is supplied to the second rolling bearing via an oil supply passage that communicates between the pump chamber and the accommodation space for the second rolling bearing, it becomes possible to supply oil directly to the second rolling bearing. This makes it possible to supply an ample amount of oil to the second rolling bearing, which is located at a relatively large axial distance from the pump rotor (the pump chamber in which the pump rotor is located) that is provided at one axial end of the output shaft, and moreover, to lubricate the first and second rolling bearings evenly.

[0010] The oil supply passage that supplies oil to the second rolling bearing may include either or both of an outer oil supply passage formed in the housing and an inner oil supply passage formed in the output shaft.

[0011] In the above configuration, the housing can be provided with a radial drain hole that discharges oil that has lubricated the second rolling bearing toward an oil recovery section. This allows the oil used for internal lubrication of the second rolling bearing to be reused, reducing the amount of new oil used. In this case, if the axial distance between the center of the drain hole and the start end of the oil supply passage is made larger than the axial distance between the center of the second rolling bearing and the start end of the oil supply passage (if the drain hole is located axially farther away from the second rolling bearing than the start end of the oil supply passage, the second rolling bearing can be lubricated efficiently. [Effects of the Invention]

[0012] As described above, according to the present invention, it is possible to evenly lubricate the two rolling bearings that rotatably support the output shaft of the electric motor, thereby realizing a high-quality, long-life electric oil pump. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic vertical cross-sectional view of an electric oil pump according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram for explaining the configuration of a pump section provided in the electric oil pump of FIG. [Figure 3] FIG. 10 is a schematic vertical cross-sectional view of an electric oil pump according to another embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view taken along the line AA in FIG. 3. [Figure 5] FIG. 10 is a schematic vertical cross-sectional view of an electric oil pump according to another embodiment of the present invention. [Figure 6] FIG. 10 is a schematic vertical cross-sectional view of an electric oil pump according to another embodiment of the present invention. [Figure 7] 1(a) and 1(b) are schematic vertical cross-sectional views showing modified examples of the first rolling bearing incorporated in the electric oil pump according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] FIG. 1 is a schematic longitudinal sectional view of an electric oil pump 1 according to one embodiment of the present invention. The electric oil pump 1 shown in the figure is mounted on a vehicle such as an automobile and used to generate oil pressure in a transmission while the engine is stopped. The electric oil pump 1 includes a pump section 2 that draws in and discharges oil, a motor section 3 that drives the pump section 2, and a housing 6 that accommodates these. The terms "axial direction," "radial direction," and "circumferential direction" used in the following description refer to a direction parallel to an axis O of the motor section 3, which is the center of rotation of the output shaft 5 of the electric motor 4, and a radial direction and a circumferential direction of a circle centered on the axis O, respectively. Furthermore, the side of the electric oil pump 1 on which the pump section 2 is located (the right side of the paper in FIG. 1 ) and the side on which the motor section 3 is located (the left side of the paper in FIG. 1 ) are referred to as the "one axial side" and the "other axial side," respectively.

[0016] An overview of the pump section 2 of this embodiment will be described with reference to FIG. 2 as well. The pump section 2 is configured as a trochoid pump having an inner rotor 21 as a pump rotor, an outer rotor 22 disposed eccentrically relative to the inner rotor 21, a suction hole 24 for drawing oil into (the internal space of) the pump chamber 6A, and a discharge hole 25 for discharging oil to the outside of the pump chamber 6A. The inner rotor 21 is formed with a plurality of (six in the illustrated example) external teeth, some of which mesh with a plurality of (seven in the illustrated example) internal teeth formed on the outer rotor 22. The inner rotor 21 is coupled to one axial end of the output shaft 5 of the electric motor 4 provided in the motor section 3 and rotates integrally with the output shaft 5 (counterclockwise in the illustrated example) around the axis O of the motor section 3. The outer rotor 22 is fitted into the pump chamber 6A in a manner that allows it to rotate around a point (point Os in the illustrated example) shifted radially outward from the axis O of the motor section 3. As a result, as the inner rotor 21 rotates together with the output shaft 5, the outer rotor 22 rotates in response.

[0017] As the rotors 21, 22 rotate in the pump section 2 configured as described above, the volume of the rotor gap 23 between the meshed external and internal teeth gradually increases, reaches a maximum volume, and then gradually decreases. In this process of volume fluctuation in the rotor gap 23, oil is drawn into the internal space of the pump chamber 6A through the suction hole 24 when the volume increases, and oil is discharged out of the pump chamber 6A through the discharge hole 25 when the volume decreases. The oil discharged through the discharge hole 25 is supplied to the transmission via hydraulic piping (not shown). As shown in FIG. 2, the diameter of the discharge hole 25 is generally set smaller than the diameter of the suction hole 24 to increase the oil discharge pressure.

[0018] The motor section 3 is equipped with a radial gap type electric motor 4 having a stator 11 fixed to the inner circumferential surface of the housing 6 (a motor chamber 6B provided therein) and a rotor 12 disposed radially inside the stator 11 and facing it with a radial gap therebetween, and is disposed axially alongside the pump section 2. The electric motor 4 is a three-phase motor (three-phase brushless motor) having U, V, and W phases. Therefore, the stator 11 has a plurality of coils 11B corresponding to the U, V, and W phases.

[0019] The stator 11 is fixed to the inner circumferential surface of the motor chamber 6B in an assembled state with a cylindrical busbar unit 13 attached to the other axial end of the stator 11. The stator 11 includes a starter core 11A having a plurality of teeth spaced apart in the circumferential direction, and a plurality of coils 11B formed by winding coil wire around the outer periphery of each tooth via an insulating member such as an insulator. As described above, the coils 11B include U-phase, V-phase, and W-phase coils, and each coil 11B is formed by so-called concentrated winding.

[0020] The busbar unit 13 includes a plurality of busbars 13A made of a metal material such as copper, and a resin busbar holder 13B that insulates and holds the plurality of busbars 13A without contacting each other. The busbar holder 13B may integrally include a portion that corresponds to the insulator described above. The busbars 13A include at least a U-phase busbar, a V-phase busbar, and a W-phase busbar. One longitudinal end of each busbar 13A is provided with a pin-shaped terminal 13A1 extending in the axial direction, and the other longitudinal end of each busbar 13A is electrically connected to (the terminal portion of the coil wire constituting) the coil 11B of the corresponding phase.

[0021] Although not shown in the figure, a circuit board holding a control unit that controls the operation of the electric motor 4 is arranged along the radial direction on the other axial side of the motor cover 9 that constitutes the housing 6, and terminals 13A1 provided on each bus bar 13A are fitted into terminal fitting holes formed in the circuit board. This electrically connects each bus bar 13A to the control unit. Power is supplied to the control unit from an external power source (not shown), and the current controlled by the control unit is supplied to each coil 11B of the electric motor 4 via the bus bar 13A.

[0022] The rotor 12 has an output shaft 5 of the electric motor 4, a rotor core 14 attached to the outer periphery of the output shaft 5 so as to be rotatable together with the output shaft 5, and a plurality of magnets 15 attached at intervals in the circumferential direction to the outer periphery of the rotor core 14. One and other axial ends of the output shaft 5 protrude axially outward from the rotor core 14, and the output shaft 5 is rotatably supported relative to the housing 6 by a first rolling bearing 16 and a second rolling bearing 17 attached to these protruding portions. The first rolling bearing 16 and the second rolling bearing 17 may be, for example, a deep groove ball bearing.

[0023] The motor unit 3 of this embodiment has a rotation angle detection unit 18 that detects the rotation angle of the rotor 12 (output shaft 5). The rotation angle detection unit 18 includes a sensor magnet 18A attached to the other axial end of the output shaft 5 via a bracket, and a rotation sensor (not shown) attached to the circuit board so as to face the sensor magnet 18A in the axial direction. The rotation sensor is electrically connected to a control unit provided on the circuit board, and its detected value is input to the control unit. As a result, the detected value by the rotation sensor is used to control the operation of the electric motor 4. Note that the rotation angle detection unit 18 is not necessarily provided and may be omitted. In other words, the motor unit 3 may be used in a sensorless state without a rotation sensor.

[0024] The housing 6 includes a cylindrical housing body 7 having open ends on one and the other axial sides, and a pump cover 8 and a motor cover 9 that close the openings at one and the other ends of the housing body 7, respectively.

[0025] The housing body 7 is provided with a pump chamber 6A that houses the pump section 2, a motor chamber 6B that houses the motor section 3, and an annular partition wall 6C that axially separates the pump chamber 6A from the motor chamber 6B. The illustrated housing body 7 is a machined product formed by machining, such as cutting, a metal material such as an aluminum alloy that has good electrical and thermal conductivity and workability. The pump cover 8 is also formed from the same metal material as the housing body 7 and is fixed to the housing body 7 using bolt members.

[0026] The motor cover 9 is made of the same metal material as the housing body 7 and integrally comprises an inner cylindrical portion 9a, on whose inner periphery the output shaft 5 (the other axial end thereof) is disposed and on which an outer ring mounting surface of the second rolling bearing 17 is provided, and an outer cylindrical portion 9b that fits onto the inner periphery of the opening at the other end of the housing body 7. The motor cover 9 has three spaced terminal insertion holes 9c, through which terminals 13A1 of the U-phase, V-phase, and W-phase bus bars 13A are individually inserted, and each terminal 13A1 is held by a terminal holding portion 13B1 provided on a resin bus bar holder 13B. This ensures insulation between the housing 6 (motor cover 9) and the bus bars 13A.

[0027] As will be described later, in the electric oil pump 1 of this embodiment, oil present in the internal space of the pump chamber 6A (oil sucked in and discharged by the pump section 2) is used to lubricate the interior of the rolling bearings 16, 17 and also to cool the electric motor 4, so oil is always present in the internal space of the motor chamber 6B. If this oil leaks out of the motor chamber 6B (housing 6) and adheres to, for example, a control section (electronic components constituting the control section) held on a circuit board, there is a risk that the control section will not operate normally.

[0028] Therefore, in the housing 6, a ring-shaped elastic member (such as an O-ring) 10 that functions as an oil seal is interposed in an elastically compressed and deformed state between the inner peripheral surface of the housing main body 7 and the opposing outer peripheral surface of the outer cylindrical portion 9b of the motor cover 9, and between the inner peripheral wall surface of the terminal insertion hole 9c provided in the motor cover 9 and the opposing outer peripheral surface of the terminal holding portion 13B1. Furthermore, the other end opening of the inner cylindrical portion 9a, on whose inner periphery the other axial end of the output shaft 5 is located, is closed with a concave-shaped cover. This configuration minimizes unintended oil leakage outside the motor chamber 6B.

[0029] As described above, in the electric oil pump 1 of this embodiment, the oil present in the internal space of the pump chamber 6A is used to provide internal lubrication for the rolling bearings 16, 17 and to cool the electric motor 4. For this reason, the electric oil pump 1 has a first oil supply passage 31 and a second oil supply passage 32 that can directly supply oil present in the pump chamber 6A to the first rolling bearing 16 and the second rolling bearing 17, respectively, as the inner rotor 21 coupled to one end of the output shaft 5 of the electric motor 2 rotates within the pump chamber 6A as the electric motor 2 is driven to rotate.

[0030] The first oil supply passage 31 is formed by an axial through-hole provided in the housing main body 7, and one longitudinal (axial) end thereof opens to the pump chamber 6A, and the other longitudinal end thereof opens to the accommodation space of the first rolling bearing 16 in the motor chamber 6B (more specifically, the position of the opening between the inner and outer rings on one axial side). Note that oil is supplied to the first rolling bearing 16 (the motor chamber 6B accommodating the first rolling bearing 16) not only through the first oil supply passage 31 but also through a radial gap formed between the inner circumferential surface of the partition wall 6C of the housing 6 and the outer circumferential surface of the output shaft 5 to ensure rotation of the output shaft 5, but the amount of oil supplied through this radial gap is smaller than the amount of oil supplied through the first oil supply passage 31.

[0031] The oil supplied to the first rolling bearing 16 (the accommodation space thereof) through the first oil supply passage 31 and the radial gap formed by the inner circumferential surface of the partition wall 6C lubricates the interior of the first rolling bearing 16 (the sliding contact portions between components), then moves downward through the internal space of the motor chamber 6B while cooling the rotor 12, stator 11, etc. of the electric motor 4, and is discharged to the outside (bottom) of the motor chamber 6B through a radial drain hole 33 provided in the housing 6 (housing main body 7). An oil tank 34 is disposed below the drain hole 33, and the oil discharged to the outside of the motor chamber 6B is collected in the oil tank 34 (see the oil level indicated by reference numeral 35 in FIG. 1). The oil collected in the oil tank 34 is returned to the pump chamber 6A for reuse.

[0032] The second oil supply passage 32 has one longitudinal end 32a that opens to (the inner wall surface of) the pump chamber 6A and the other longitudinal end that opens to (the inner wall surface of) the accommodation space for the second rolling bearing 17 in the motor chamber 6B, thereby communicating between the pump chamber 6A and the accommodation space for the second rolling bearing 17. The second oil supply passage 32 in this embodiment is constituted by an outer oil supply passage 40 formed in the housing 6, and is provided separately from the radial gap provided between the stator 11 and the rotor 12 to ensure rotation of the rotor 12. The outer oil supply passage 40 is provided in the housing body 7 so that one longitudinal end opens to the inner wall surface of the pump chamber 6A and the other longitudinal end opens to the end face on the other axial side of the housing body 7, and is composed of a curved communication hole 41 that connects the pump chamber 6A to the annular space 19 defined between the inner cylindrical portion 9a and the outer cylindrical portion 9b of the motor cover 9 (between the motor cover 9 and the bus bar unit 13), and a communication hole 42 whose one and other longitudinal ends open to the inner and outer circumferential surfaces of the inner cylindrical portion 9a of the motor cover 9, respectively, and that connects the annular space 19 to the storage space for the second rolling bearing 17.

[0033] 2, one longitudinal end 32a of the second oil supply passage 32 (outer oil supply passage 40) provided to lubricate the second rolling bearing 17, which is an opening to the pump chamber 6A, is disposed at a position on the inner wall surface of the pump chamber 6A that radially overlaps with the outer diameter surface of the outer rotor 22. This is because if one end 32a of the second oil supply passage 32 were to open at a position that radially overlaps with the inter-rotor gap 23, more oil than necessary would be supplied to the second oil supply passage 32, and therefore to the second rolling bearing 17, increasing the possibility of degrading the function of the electric oil pump 1.

[0034] Furthermore, if one end 32a of the second oil supply passage 32 opens at a position close to the oil suction hole 24, there is a concern that the amount of oil flowing into the second oil supply passage 32 and, ultimately, the amount of oil supplied to the second rolling bearing 17 may decrease due to the suction force generated at the suction hole 24 when the electric oil pump 1 is driven. Therefore, it is preferable to arrange one end (one end opening) 32a of the second oil supply passage 32 at a position where the circumferential distance from the discharge hole 25 is smaller than the circumferential distance from the suction hole 24 (i.e., a position closer to the discharge hole 25 in the circumferential direction than the suction hole 24). For example, in the case of this embodiment, one end 32a of the second oil supply passage 32 is arranged within the circumferential range indicated by the symbol W in FIG. 2. Furthermore, by providing one end 32a of the second oil supply passage 32 so as to be directly connected to the pump chamber 6A, the number of parts and processing costs can be reduced compared to, for example, providing one end 32a of the second oil supply passage 32 so as to be directly connected to the suction hole 24 or the discharge hole 25.

[0035] The illustrated bent communication hole 41 provided in the housing body 7, which is a machined product of a metal material, can be, for example, (1) An inclined through-hole inclined with respect to the axial direction (radial direction) and an axial through-hole extending in the axial direction radially outward from the motor chamber 6B are formed so that they intersect at a predetermined position in the housing body 7, and then, (2) Filling the portion of the inclined through-hole that is radially outward from the intersection of the two through-holes (the portion shown by the broken line in FIG. 1 ) and the portion of the axial through-hole that is on one side of the intersection of the two through-holes in the axial direction (the portion shown by the broken line in FIG. 1 ). It can be formed by following these steps.

[0036] As in the electric oil pump 1 of the present embodiment described above, an oil supply passage (second oil supply passage) 32 is provided that connects the pump chamber 6A to the accommodation space of the second rolling bearing 17 in the motor chamber 6B, in addition to the gap (radial gap) that is normally provided between the rotor 12 and the stator 11 to ensure rotation of the rotor 12 of the motor unit 3. If oil is supplied to the second rolling bearing 17 via this second oil supply passage 32, it becomes possible to directly supply oil to the second rolling bearing 17. This makes it possible to supply an ample amount of oil to the second rolling bearing 17, of the first rolling bearing 16 and the second rolling bearing 17, which has a relatively large axial separation distance from the inner rotor 21 (in which the pump chamber 6A is disposed) that is provided at one axial end of the output shaft 5. This makes it possible to equally lubricate the first rolling bearing 16 and the second rolling bearing 17. This makes it possible to realize an electric oil pump 1 that is high quality and has a long life.

[0037] The oil supplied to (or near) the second rolling bearing 17 in the motor chamber 6B moves downward through the internal space of the motor chamber 6B while providing internal lubrication to the second rolling bearing 17 and cooling the stator 11 and rotor 12 of the electric motor 4, and is discharged to the underside of the motor chamber 6B through the drain hole 33.

[0038] Here, the hole center C2 of the drain hole 33 is located on the other axial side of the bearing center C1 of the second rolling bearing 17. In other words, the axial distance between the hole center C2 of the drain hole 33 and the start end (one longitudinal end 32a) of the second oil supply passage 32 is greater than the axial distance between the bearing center C1 of the second rolling bearing 17 and one longitudinal end 32a of the second oil supply passage 32. This allows the second rolling bearing 17 to be lubricated efficiently.

[0039] Although the electric oil pump 1 according to one embodiment of the present invention has been described above, the present invention is not limited to this embodiment.

[0040] Fig. 3 shows a schematic vertical cross-sectional view of an electric oil pump 1 according to another embodiment of the present invention. Note that, although the pump cover 8 shown in Fig. 1 is omitted in Fig. 3, in the completed electric oil pump 1, one opening end of the pump chamber 6A is sealed with the pump cover 8.

[0041] The electric oil pump 1 shown in FIG. 3 differs from the one shown in FIG. 1 in the following points: In addition to the outer oil supply passage 40 formed in the housing 6, an inner oil supply passage 50 formed in the output shaft 5 is provided as the second oil supply passage 32 for supplying oil from the pump chamber 6A to the second rolling bearing 17 as the output shaft 5 and the pump rotor 21 rotate; An axial communication passage is provided between the outer peripheral surface of the output shaft 5 and the inner peripheral surface of the rotor core 14, which connects both axial sides of the rotor 12 together.

[0042] Regarding the first difference, the inner oil supply passage 50 in the illustrated example is formed by combining an axial hole 51 that penetrates the output shaft 5 in the axial direction and a radial hole 52 that penetrates the output shaft 5 in the radial direction. The radial hole 52 is provided so as to open to an axial region of the outer surface of the output shaft 5 that faces the partition wall 6C of the housing 6 and an axial region adjacent to the other axial side of the second rolling bearing 17. In this case, when the pump rotor 21 rotates in conjunction with the rotation of the output shaft 5, oil in the pump chamber 6A flows into the outer oil supply passage 40 formed in the housing 6 and the inner oil supply passage 50 formed in the output shaft 5, and is supplied to the accommodation space of the second rolling bearing 17 via both oil supply passages 40, 50. This allows for more efficient lubrication of the second rolling bearing 17.

[0043] Regarding the second difference, the axial communication passage is formed, for example, by providing an axial groove 14a on the inner peripheral surface of the rotor core 14, as shown in FIG. 4. This axial communication passage can also be formed by providing an axial groove on the outer peripheral surface of the output shaft 5. By providing such a communication passage, oil that passes through (lubricates) the internal space of the first rolling bearing 16 and reaches the other axial side of the first rolling bearing 16 (one axial side of the rotor 12) can be supplied to the other axial side of the rotor 12, i.e., the second rolling bearing 17, via the axial communication passage. This allows the second rolling bearing 17 to be lubricated even more efficiently. The above-mentioned communication passage provided between the output shaft 5 and the rotor core 14 may also be provided in the electric oil pump 1 shown in FIG. 1.

[0044] Figure 5 shows a schematic vertical cross-sectional view of an electric oil pump 1 according to another embodiment of the present invention. As with the electric oil pump 1 shown in Figure 3, the pump cover 8 shown in Figure 1 is also omitted from the electric oil pump 1 shown in this figure, but in the completed product state, one opening at one end of the pump chamber 6A is sealed with the pump cover 8.

[0045] The electric oil pump 1 of this embodiment differs mainly from the electric oil pump 1 shown in FIG. 1 in that the housing 6 is made up of a first housing forming member 61 that corresponds to a portion of the housing main body 7 and the motor cover 9 integrated together, a second housing forming member 62 that corresponds to the remaining portion of the housing main body 7, and a pump cover 8 (not shown).

[0046] Figure 6 shows a schematic vertical cross-sectional view of an electric oil pump 1 according to another embodiment of the present invention. As with the electric oil pump 1 shown in Figure 3, the pump cover 8 shown in Figure 1 is also omitted from the electric oil pump 1 shown in this figure, but in the completed product state, one opening at one end of the pump chamber 6A is sealed with the pump cover 8.

[0047] The electric oil pump 1 of this embodiment differs mainly from the electric oil pump 1 shown in Fig. 1 in that the housing main body 7 is not a machined product made of metal material, but is a product formed by a 3D printer. With such a product, it is possible to form a curved oil supply passage (second oil supply passage 32) without combining through holes in the axial direction and the radial direction (diagonal directions inclined at a predetermined angle relative to the radial direction). This eliminates the need for a hole filling process, i.e., sealing the portions of the through holes that make up the oil supply passage 32 that do not become the oil supply passage 32 (for example, the portions shown by dashed lines in Fig. 1, etc.).

[0048] The first rolling bearing 16 incorporated into the electric oil pump 1 described above is a sealless type rolling bearing in which the openings on both one axial side (pump side) and the other axial side (motor side) between the inner and outer rings are open, but the first rolling bearing 16 can also be replaced with a sealed type as shown in Figures 7(a) and 7(b). The rolling bearing shown in Figure 7(a) is a one-sided sealed type that has a seal member Sa that seals the motor side opening, while the rolling bearing (first rolling bearing 16) shown in Figure 7(b) is a double-sided sealed type that has a seal member Sa that seals the motor side opening and a perforated seal member Sb (a seal member that allows oil to pass between the inside and outside of the bearing via a through hole) that is arranged at the pump side opening. When a first rolling bearing 16 such as that illustrated in Figures 7(a) and (b) is adopted, the oil that has flowed into the internal space is allowed to flow actively while the retention of the oil that has flowed into the internal space is improved, thereby enhancing the lubrication effect of the first rolling bearing 16.

[0049] Although not shown, the second rolling bearing 17 can also be replaced from a sealless type to a sealed type, as with the first rolling bearing 16. In this case, the position of the seal member can be determined depending on the terminal position of the second oil supply passage 32. For example, in the electric oil pump 1 of the embodiment shown in FIG. 1 , the terminal opening of the second oil supply passage 32 is located on the other axial side of the second rolling bearing 17. Therefore, if a sealed rolling bearing of the type in which the pump unit side opening between the inner and outer rings is sealed with a seal member is used as the second rolling bearing 17, the oil that has flowed into the internal space of the second rolling bearing 17 can be allowed to actively flow into the internal space while improving the retention of the oil that has flowed into the internal space.

[0050] The present invention is not limited to the above-described embodiment, and can be embodied in various other forms without departing from the spirit of the present invention. [Explanation of symbols]

[0051] 1 Electric oil pump 2 Pump section 3 Motor section 4 electric motors 5 Output shaft 6. Housing 6A Pump Room 6B Motor Room 7 Housing body 8 Pump cover 9 Motor cover 11 Stator 11B coil 12 rotors 16 First rolling bearing 17 Second rolling bearing 21 Inner rotor (pump rotor) 22 Outer Rotor 23 Rotor clearance 24 Suction hole 25 Discharge hole 31 First Fuel Line 32 Second fuel line 33 Drain hole 40 Outside oil supply path 50 Inner oil supply line O axis

Claims

1. The oil pump includes a pump section that sucks and discharges oil, a motor section that drives the pump section, and a housing that accommodates the pump section and the motor section in a state where they are aligned in the axial direction. an output shaft of the motor unit is rotatably supported with respect to the housing by first and second rolling bearings disposed on one and the other axial sides of a rotor coupled to the outer periphery of the output shaft of the motor unit, an electric oil pump in which a pump rotor provided at one axial end of the output shaft rotates within a pump chamber as the output shaft rotates, thereby sucking and discharging the oil, and the oil in the pump chamber is supplied to the first and second rolling bearings via an oil supply passage, an oil supply passage for supplying the oil to the second rolling bearing communicates the pump chamber with a space for accommodating the second rolling bearing;

2. The electric oil pump according to claim 1 , wherein the oil supply passage that supplies the oil to the second rolling bearing includes an outer oil supply passage formed in the housing.

3. The electric oil pump according to claim 1 , wherein the oil supply passage that supplies the oil to the second rolling bearing includes an inner oil supply passage formed in the output shaft.

4. a radial drain hole for discharging the oil that has lubricated the second rolling bearing into an oil tank is provided in the housing; 2. The electric oil pump according to claim 1, wherein the axial distance between the center of the drain hole and the start end of the oil supply passage is greater than the axial distance between the center of the second rolling bearing and the start end of the oil supply passage.

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