Vehicle drive systems

Abstract

This technology provides a way to suppress the deterioration of noise transmitted from rotating electrical machinery to the case. [Solution] The vehicle drive system disclosed herein comprises a rotating electric machine having a hollow output shaft, a case housing the rotating electric machine, an intermediate shaft extending through a through hole in the output shaft along the axial direction of the rotating electric machine and transmitting the torque of the rotating electric machine toward the wheels of the vehicle, and a bearing having an outer ring fixed to the case and an inner ring fixed to the output shaft, which rotatably supports the output shaft relative to the case, wherein the intermediate shaft has a first passage for supplying refrigerant to the rotating electric machine, the case has a second passage for supplying refrigerant to the first passage, and a part of the second passage extends in the vicinity of the outer ring fixed to the case along the circumferential direction of the outer ring.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a vehicle drive device.

Background Art

[0002] Patent Document 1 discloses a hollow output shaft having a rotating electric machine, and an intermediate shaft extending along the axial direction of the rotating electric machine within the through-hole of the output shaft. The intermediate shaft transmits the torque of the rotating electric machine toward the vehicle wheels. Further, the output shaft is rotatably supported with respect to a case that houses the rotating electric machine via a bearing.

[0003] A flow path for supplying refrigerant to the rotating electric machine is provided in the intermediate shaft. Refrigerant is supplied to the flow path provided in the intermediate shaft from a flow path provided in the case that houses the rotating electric machine.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As the temperature inside the case rises, a gap may occur between the bearing and the case. This is because the linear expansion coefficient of the bearing and the linear expansion coefficient of the case are different. This gap causes deterioration of the noise transmitted from the rotating electric machine to the case. In this specification, a technology for suppressing the deterioration of the noise transmitted from the rotating electric machine to the case is provided.

Means for Solving the Problems

[0006] The vehicle drive system disclosed herein comprises a rotating electric machine having a hollow output shaft; a case housing the rotating electric machine; an intermediate shaft extending through a through hole in the output shaft along the axial direction of the rotating electric machine and transmitting torque from the rotating electric machine toward the wheels of a vehicle; and a bearing having an outer ring fixed to the case and an inner ring fixed to the output shaft, which rotatably supports the output shaft relative to the case, wherein the intermediate shaft has a first passage for supplying refrigerant to the rotating electric machine, and the case has a second passage for supplying refrigerant to the first passage, and a portion of the second passage extends in the vicinity of the outer ring fixed to the case, along the circumferential direction of the outer ring.

[0007] In the above-described vehicle drive system, a portion of the second flow path provided in the case extends circumferentially near the outer ring of the bearing. As a result, both the bearing and the case are cooled by the second flow path. Cooling of both the bearing and the case suppresses thermal expansion of the bearing and the case, thereby suppressing the formation of a gap between the bearing and the case. Consequently, the deterioration of noise transmitted from the rotating electric machine to the case is suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram provides a schematic overview of the vehicle's configuration. [Figure 2] This is a diagram showing the skeleton of the drive system installed in the vehicle. [Figure 3] This is a cross-sectional view of the output shaft and the main parts around the bearing. [Figure 4] This is a cross-sectional view along the line IV-IV in Figure 3. [Modes for carrying out the invention]

[0009] The following describes the drive system mounted on the vehicle, referring to the drawings. Here, the directions in some of the drawings correspond to the vehicle's direction. Direction FR indicates the front in the vehicle's longitudinal direction, and direction RR indicates the rear in the vehicle's longitudinal direction. Direction LH indicates the left in the vehicle's lateral direction, and direction RH indicates the right in the vehicle's lateral direction. Direction UP indicates the upward in the vehicle's vertical direction, and direction DW indicates the downward in the vehicle's vertical direction.

[0010] Figure 1 shows the configuration of Vehicle 1. Vehicle 1 is a vehicle that has at least a rotating electric machine as one of its drive sources, and may be, for example, an electric vehicle, a hybrid vehicle, or a fuel cell vehicle.

[0011] Vehicle 1 comprises a battery pack 2 mounted beneath the floor and a pair of drive units 3. The battery pack 2 supplies power to each of the pair of drive units 3. One of the pair of drive units 3 uses the supplied power to drive the front wheels FW, and the other of the pair of drive units 3 uses the supplied power to drive the rear wheels RW. Although vehicle 1 is exemplified as a four-wheel drive vehicle, it may also be a two-wheel drive vehicle equipped with only one of the pair of drive units 3. The pair of drive units 3 have a common structure. Hereafter, the pair of drive units 3 will be described without distinction.

[0012] The drive unit 3 comprises a rotating electric machine 4, a transmission device 5, a power control unit 6, and a case 7. The rotating electric machine 4, the transmission device 5, and the power control unit 6 are housed within the case 7. The power control unit 6 is positioned adjacent to the rotating electric machine 4 and the transmission device 5 in the longitudinal direction of the vehicle (rear in this example). The power control unit 6 converts the power supplied from the battery pack 2 from direct current to alternating current and supplies it to the rotating electric machine 4. The rotating electric machine 4 generates driving force based on the alternating current power supplied from the power control unit 6. The transmission device 5 amplifies the driving force generated by the rotating electric machine 4 into torque and then distributes it to the left and right wheels.

[0013] The rotating electric machine 4 and the transmission device 5 are arranged coaxially. As a result, the vertical size of the case 7 housing the rotating electric machine 4 and the transmission device 5 is reduced. Consequently, the case 7 is positioned so that, when viewed from the left or right direction of the vehicle, it fits within the range of the corresponding wheels FW and RW. As a result, for example, at the front of the vehicle 1, the degree of freedom in arranging various mechanical components, such as the radiator and the air conditioning control system, is improved, and a larger user space can be secured. Furthermore, at the rear of the vehicle 1, for example, a larger trunk space can be secured, or the range of the rear seat reclining angle can be widened.

[0014] Figure 2 shows a skeleton diagram of the drive unit 3, including the rotating electric machine 4 and the transmission device 5 housed in the case 7. In this example, the rotating electric machine 4 is located on the right side of the case 7, and the transmission device 5 is located on the left side of the case 7. Alternatively, the transmission device 5 may be located on the right side of the case 7, and the rotating electric machine 4 on the left side of the case 7. In the following explanation, for convenience, the names of the components may include left-right directions, but such designations do not limit the position of the components.

[0015] The rotating electric machine 4 comprises a stator core 12, a rotor 14, and an output shaft 16. The stator core 12 is fixed to the case 7. The rotor 14 is supported by the case 7 so as to be rotatable around the rotation axis of the rotating electric machine 4. The output shaft 16 is connected to the rotor 14 and rotates together with the rotor 14. The output shaft 16 is hollow and has a through hole 18 that extends along the rotation axis of the rotating electric machine 10.

[0016] The transmission device 5 comprises a planetary gear section 20 and a differential gear 30. The planetary gear section 20 reduces the rotation of the output shaft 16 of the rotating electric machine 4. The differential gear 30 distributes the driving force of the rotating electric machine 4 transmitted via the planetary gear section 20 to the right wheel 8 and the left wheel 9. The rotating electric machine 4, the planetary gear section 20, and the differential gear 30 are arranged coaxially. Note that the configuration of the transmission device 5 described below is just one example, and other types of configurations can be adopted as appropriate.

[0017] The planetary gear section 20 comprises a sun gear 22, a plurality of stepped pinion gears 24, a ring gear 26, and a carrier 28. The sun gear 22 is connected to the output shaft 16 of the rotating electric machine 4 and rotates together with the output shaft 16. Each of the plurality of stepped pinion gears 24 has a large-diameter pinion gear P1 and a small-diameter pinion gear P2 which is smaller in diameter than the large-diameter pinion gear P1. The large-diameter pinion gear P1 meshes with the sun gear 22. The small-diameter pinion gear P2 meshes with the ring gear 26. The ring gear 26 is fixed to the case 7. The carrier 28 rotatably supports each of the plurality of stepped pinion gears 24. Thus, in the planetary gear section 20, the sun gear 22 is the input element, the ring gear 26 is the reaction element, and the carrier 28 is the output element.

[0018] The differential gear 30 comprises a differential case 31 and a differential gear mechanism 32. The differential case 31 is supported by the case 7 so as to be rotatable around the rotation axis of the rotating electric machine 4. The differential case 31 is connected to the carrier 28 of the planetary gear section 20 and rotates together with the carrier 28. The differential gear mechanism 32 is housed within the differential case 31.

[0019] The differential gear mechanism 32 comprises a pinion shaft 33, a pair of differential pinion gears 34 and 35, a right-side gear 36, and a left-side gear 37.

[0020] The pinion shaft 33 is connected to the differential case 31 and rotates integrally with the differential case 31. The pinion shaft 33 extends in the differential case 31 along a direction orthogonal to the rotation axis direction of the rotating electric machine 4. Each of the pair of differential pinion gears 34, 35 is supported by the pinion shaft 33 so as to be rotatable around the axis of the pinion shaft 33. The right side gear 36 is a member that outputs a driving force to the right wheel 8 and meshes with each of the pair of differential pinion gears 34, 35. The left side gear 37 is a member that outputs a driving force to the left wheel 9 and meshes with each of the pair of differential pinion gears 34, 35.

[0021] The drive device 3 further includes an intermediate shaft 40, a right drive shaft 5 connected to the right wheel 8, and a left drive shaft 60 connected to the left wheel 9.

[0022] The intermediate shaft 40 extends in the through hole 18 of the output shaft 16 along the rotation axis direction of the rotating electric machine 4. The left end portion of the intermediate shaft 40 is connected to the right side gear 36 of the differential gear 30, and the right end portion of the intermediate shaft 40 is connected to the right drive shaft 50. That is, the intermediate shaft 40 transmits the torque of the rotating electric machine 4 transmitted through the output shaft 16, the planetary gear unit 20, and the differential gear mechanism 32 to the right wheel 8.

[0023] The right drive shaft 50 has a drive shaft inboard 52, an intermediate drive shaft 54, and a drive shaft outboard 56. The drive shaft inboard 52 is the left end portion on the side inserted into the case 7 among both end portions in the axial direction of the right drive shaft 50, and refers to the portion from the constant velocity joint to the left end face. The drive shaft outboard 56 is the right end portion on the side connected to the right wheel 8 among both end portions in the axial direction of the right drive shaft 50, and refers to the portion from the constant velocity joint to the right end face. The drive shaft inboard 52 of the right drive shaft 50 is connected to the right side gear 36 of the differential gear 30 via the intermediate shaft 40. The driving force output by the right side gear 36 is transmitted to the right drive shaft 50 via the intermediate shaft 40.

[0024] The left drive shaft 60 has a drive shaft inboard 62, an intermediate drive shaft 64, and a drive shaft outboard 66. The drive shaft inboard 62 is the right end portion on the side inserted into the case 7 among both end portions in the axial direction of the left drive shaft 60, and refers to the portion from the constant velocity joint to the right end face. The drive shaft outboard 66 is the left end portion on the side connected to the left wheel 9 among both end portions in the axial direction of the left drive shaft 60, and refers to the portion from the constant velocity joint to the left end face. The drive shaft inboard 62 of the left drive shaft 60 is connected to the left side gear 37 of the differential gear 30. The driving force output by the left side gear 37 is directly transmitted to the left drive shaft 60.

[0025] FIG. 3 shows a cross-sectional view in the vicinity of the drive shaft inboard 52 of the intermediate shaft 40 and the right drive shaft 50. A fitting hole 42 into which the left end portion of the drive shaft inboard 52 fits is provided at the right end portion of the intermediate shaft 40. A through hole 72 through which both the right end portion of the intermediate shaft 40 and the left end portion of the drive shaft inboard 52 pass is provided in the case 7.

[0026] A bearing 74 is fixed to the case 7, which is positioned coaxially with the through-hole 72. The outer ring 74B of the bearing 74 is fixed to the inner surface of the case 7. The inner ring 74A of the bearing 74 is fixed to the outer surface of the right end of the output shaft 16. The bearing 74 rotatably supports the output shaft 16 relative to the case 7.

[0027] The drive unit 3 has a passage through which lubricating fluid 300 flows for lubricating and cooling the parts to be lubricated within the rotating electric machine 4 and the transmission unit 5. This passage is provided in the intermediate shaft 40 and the case 7.

[0028] The intermediate shaft 40 is provided with a first flow path 82 that extends along the axial direction of the intermediate shaft 40. One end of the first flow path 82 opens to the bottom surface 45 of the fitting hole 42. The intermediate shaft 40 is provided with one or more supply holes that extend from the first flow path 82 to the outer surface in a direction perpendicular to the axial direction of the intermediate shaft 40 at the location where the part to be lubricated is located. The lubricating fluid 300 supplied to the first flow path 82 is supplied to the part to be lubricated from one or more supply holes.

[0029] Case 7 is provided with a second channel 84 that supplies lubricating fluid 300 to the first channel 82. As shown in Figures 3 and 4, the second channel 84 has a first partial channel 202, a second partial channel 204, and a third partial channel 206. One end of the first partial channel 202 opens to a surface defining the passage opening 72. The other end of the first partial channel 202 is connected to one end of the second partial channel 204. As shown in Figure 4, the second partial channel 204 extends in the vicinity of the outer ring 74B of the bearing 74, along the circumferential direction of the outer ring 74B. The second partial channel 204 extends over an angular range of 180 degrees or more in the circumferential direction of the outer ring 74B. In this embodiment, the angular range is approximately 360 degrees. Approximately 360 degrees is, for example, a value within the range of 330 degrees to 360 degrees.

[0030] The other end of the second partial flow path 204 is connected to one end of the third partial flow path 206. An oil cooler 310 is connected to the other end of the third partial flow path 206. The oil cooler 310 performs heat exchange between the other refrigerant 302 and the lubricating fluid 300. The other refrigerant 302 flows in a separate flow path isolated from the flow path through which the lubricating fluid 300 flows. The oil cooler 310 is configured to cool the lubricating fluid 300 supplied to the third partial flow path 206. In a modified example, the drive unit 3 may not be equipped with the oil cooler 310.

[0031] A third passage 86 is provided in the portion formed by both the right end of the intermediate shaft 40 and the left end of the drive shaft inboard 52. The third passage 86 has a first communication passage 181 provided in the intermediate shaft 40 and a second communication passage 182 provided in the drive shaft inboard 52.

[0032] The first communication channel 181 is a through-hole that penetrates the intermediate shaft 40 along its radial direction, specifically the portion of the intermediate shaft 40 located around the fitting hole 42. One end of the first communication channel 181 opens to the outer circumferential surface 46 of the intermediate shaft 40, and the other end opens to the inner circumferential surface 43 of the intermediate shaft 40. When viewed radially along the intermediate shaft 40, the area where the second channel 84 exists at the passage opening 72 of the case 7 overlaps with the area where the first communication channel 181 exists on the outer circumferential surface 46 of the intermediate shaft 40.

[0033] The second communication channel 182 is a through-hole extending within the drive shaft inboard 52. One end of the second communication channel 182 opens to the outer circumferential surface 53 of the drive shaft inboard 52, and the other end of the second communication channel 182 opens to the left end surface 51 of the drive shaft inboard 52. The first communication channel 181 and the second communication channel 182 face each other between the inner circumferential surface 43 of the intermediate shaft 40 and the outer circumferential surface 53 of the drive shaft inboard 52.

[0034] The arrows extending from the oil cooler 310 and the arrows shown within each of the passages 82, 84, and 86 indicate the direction of the lubricating fluid 300 flowing from the oil cooler 310 through each of the passages 82, 84, and 86. The lubricating fluid 300 supplied from the oil cooler 310 to the third partial passage 206 passes through the second partial passage 204 and is supplied to the first partial passage 202. The lubricating fluid 300 supplied to the first partial passage 202 is supplied to the first connecting passage 181 of the third passage 86. The lubricating fluid 300 supplied to the first connecting passage 181 passes through the second connecting passage 182 and is supplied to the first passage 82. The lubricating fluid 300 supplied to the first passage 82 is supplied to the lubricating part and returns to the oil cooler 310.

[0035] (Effects of this embodiment) As the temperature inside case 7 rises, a gap may form between the bearing 74 and case 7. This is because the materials of the bearing 74 and case 7 are different, resulting in different coefficients of thermal expansion for the bearing 74 and case 7. For example, the material of the bearing 74 is iron, and the material of case 7 is aluminum. This gap can worsen the noise transmitted from the rotating electric machine 4 to case 7.

[0036] In this embodiment, the second partial flow path 204 extends circumferentially near the outer ring 74B of the bearing 74. As a result, both the bearing 74 and the case 7 are cooled by the second partial flow path 204. Cooling of both the bearing 74 and the case 7 suppresses thermal expansion of the bearing 74 and the case 7, thereby suppressing the formation of a gap between the bearing 74 and the case 7. Consequently, the deterioration of noise transmitted from the rotating electric machine 4 to the case 7 is suppressed.

[0037] Furthermore, in this embodiment, the second partial flow path 204 extends over an angular range of 180 degrees or more in the circumferential direction of the outer ring 74B. This allows more than half of the entire circumference of the outer ring 74B of the bearing 74 to be cooled. In a modified example, the second partial flow path 204 may extend over an angular range of less than 180 degrees in the circumferential direction of the outer ring 74B.

[0038] Furthermore, as shown in Figure 3, a plurality of heat dissipation fins 76 are provided on the outer surface of the case 7. The direction in which the heat dissipation fins 76 extend may be vertical or horizontal. The second flow path 84, in particular the first partial flow path 202, passes through the area of ​​the case 7 where the heat dissipation fins 76 are provided. The heat dissipation fins 76 can promote heat dissipation of the lubricating fluid 300 in the second flow path 84. In modified cases, the drive unit 3 may not be provided with heat dissipation fins 76.

[0039] (Correspondence) The drive unit 3 is an example of a "vehicle drive unit". The rotating electric machine 4 and case 7 are examples of a "rotating electric machine" and a "case", respectively. The lubricating fluid 300 is an example of a "refrigerant". The right wheel 8 is an example of a "wheel". The output shaft 16 and through hole 18 are examples of an "output shaft" and a "through hole", respectively. The intermediate shaft 40 is an example of an "intermediate shaft". The bearing 74, inner ring 74A, and outer ring 74B are examples of a "bearing," "outer ring," and "inner ring", respectively. The first passage 82 and second passage 84 are examples of a "first passage" and a "second passage", respectively. The oil cooler 310 is an example of a "cooler". The heat dissipation fin 76 is an example of a "heat dissipation fin".

[0040] The following points should be noted regarding the technology shown in the embodiment. The drive unit 3 does not necessarily have to have a third passage 86. In this modified example, the drive shaft inboard 52 does not necessarily have to have an additional passage 72. Furthermore, the second passage 84 may be in direct communication with the first passage 82. [Explanation of Symbols]

[0041] 1: Vehicle, 2: Battery pack, 3: Drive unit, 4: Rotating electric machine, 5: Transmission device, 6: Power control unit, 7: Case, 8: Right wheel, 9: Left wheel, 10: Rotating electric machine, 12: Stator core, 14: Rotor, 16: Output shaft, 18: Through hole, 20: Planetary gear section, 22: Sun gear, 24: Stepped pinion gear, 26: Ring gear, 28: Carrier, 30: Differential gear, 31: Differential case, 32: Differential gear mechanism, 33: Pinion shaft, 34: Differential pinion gear, 35: Differential pinion gear, 36: Right side gear, 37: Left side gear, 40: Intermediate shaft, 42: Fitting hole, 43: Inner surface, 45: Bottom surface 46: Outer surface, 50: Right drive shaft, 51: Left end surface, 52: Drive shaft inboard, 53: Outer surface, 54: Intermediate drive shaft, 56: Drive shaft outboard, 60: Left drive shaft, 62: Drive shaft inboard, 64: Intermediate drive shaft, 66: Drive shaft outboard, 72: Through port, 74: Bearing, 74A: Inner ring, 74B: Outer ring, 76: Heat dissipation fin, 82: First passage, 84: Second passage, 86: Third passage, 181: First connecting passage, 182: Second connecting passage, 202: First partial passage, 204: Second partial passage, 206: Third partial passage, 300: Lubricating fluid, 302: Other refrigerants, 310: Oil cooler, FW: Front wheels, RW: Rear wheels P1: Large diameter pinion gear, P2: Small diameter pinion gear

Claims

1. A rotating electric machine having a hollow output shaft, A case for housing the aforementioned rotating electric machine, An intermediate shaft extends through the through-hole of the output shaft along the axial direction of the rotating electric machine and transmits the torque of the rotating electric machine toward the wheels of the vehicle, A bearing having an outer ring fixed to the case and an inner ring fixed to the output shaft, which rotatably supports the output shaft relative to the case, It is equipped with, The intermediate shaft has a first flow path for supplying refrigerant to the rotating electric machine, The case has a second channel for supplying the refrigerant to the first channel, A portion of the second flow path extends in the vicinity of the outer ring fixed to the case, along the circumferential direction of the outer ring. Vehicle drive system.

2. The vehicle drive device according to claim 1, wherein the second flow path extends over an angular range of 180 degrees or more in the circumferential direction.

3. The cooler is provided for cooling the refrigerant, The vehicle drive device according to claim 1 or 2, wherein the cooler is configured to cool the refrigerant supplied to the second flow path.

4. The case is provided with a plurality of heat dissipation fins on its outer surface, The vehicle drive device according to claim 1 or 2, wherein the second flow path passes through the area of ​​the case in which the heat dissipation fins are provided.

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