Oil-cooled powertrains and electric vehicles

Abstract

This application provides an oil-cooled powertrain and an electric vehicle. The oil-cooled powertrain includes a housing, a motor, and a drive shaft. The housing includes a motor slot and an end cover. The motor slot accommodates and secures the motor stator, and the end cover encloses the motor slot. One end of the motor shaft extends into the motor slot, and the other end extends out of the motor slot and is connected to the drive shaft of a reducer. The motor shaft and the drive shaft are arranged in parallel, and the drive shaft is used to drive the differential of the reducer. One end of the drive shaft extends out of the motor slot through the shaft cavity of the motor shaft and is connected to the differential; the other end is connected to the wheel of the electric vehicle. Cooling oil passages are formed by the motor shaft cavity and the drive shaft at radial intervals along the motor. The end cover includes a mounting groove for mounting an annular oil guide plate. The oil inlet of the annular oil guide plate receives cooling oil output from the internal flow channel of the end cover, and the oil outlet of the annular oil guide plate delivers cooling oil. This design improves motor performance and increases the driving range of the electric vehicle.

Description

Technical Field

[0001] This application relates to the field of electric vehicles, specifically to an oil-cooled powertrain and an electric vehicle. Background Technology

[0002] High power density and high torque density of the drive motor in the powertrain of electric vehicles can improve the driving range of electric vehicles. Improving the heat dissipation performance of the drive motor has become an important way to improve the high torque density and high power density of the drive motor.

[0003] Typically, powertrains include oil guides that direct cooling oil into the shaft cavity of the drive motor to dissipate heat. However, existing oil guides have poor guiding performance, which affects the heat dissipation performance of the drive motor, hindering the improvement of the drive motor's power density and torque density, and consequently reducing the driving range of electric vehicles. Summary of the Invention

[0004] This application provides an oil-cooled powertrain and an electric vehicle. The oil-cooled powertrain has high oil guiding performance, which can improve the heat dissipation performance of the drive motor, which is conducive to improving the high power density and high torque density of the drive motor, and thus helps to improve the driving range of the electric vehicle.

[0005] In a first aspect, embodiments of this application provide an oil-cooled powertrain. The housing of the oil-cooled powertrain includes a motor slot and a motor end cover. The motor slot is used to accommodate and fix the stator of the drive motor of the oil-cooled powertrain. The motor end cover is used to enclose the motor slot. One end of the motor shaft is used to extend into the motor slot, and the other end of the motor shaft of the drive motor is used to extend out of the motor slot and be connected to the transmission shaft of the reducer. The motor shaft and the transmission shaft are arranged in parallel. The transmission shaft is used to connect to the differential of the reducer. The oil-cooled powertrain includes a drive shaft. One end of the drive shaft extends out of the motor slot through the shaft cavity of the motor shaft and is connected to the differential. The other end of the drive shaft is used to connect to the wheel of the electric vehicle.

[0006] In the oil-cooled powertrain provided in this application embodiment, one end of the motor shaft is used to fix the rotor of the drive motor, and the other end of the motor shaft is used to fix the driving gear of the first-stage gear set of the reducer. That is to say, the motor shaft of the drive motor serves as both the transmission shaft of the drive motor and the shaft that drives the driving gear of the first-stage gear set of the reducer to rotate, and the motor shaft of the drive motor and the input shaft of the reducer are set to the same shaft. In addition, the motor shaft and the transmission shaft are arranged in parallel, so the oil-cooled powertrain provided in this application embodiment can also be called an offset coaxial oil-cooled powertrain.

[0007] The motor shaft cavity and the drive shaft are spaced radially along the drive motor to form a cooling oil passage. The motor end cover includes an oil guide plate mounting groove for mounting an annular oil guide plate. The motor shaft and the annular oil guide plate are arranged axially along the drive motor. The annular oil guide plate includes an oil inlet and an oil outlet. The oil inlet is oriented radially along the drive motor, and the oil outlet is oriented axially along the drive motor. The oil inlet of the annular oil guide plate receives cooling oil output from the internal flow channel of the motor end cover, and the oil outlet of the annular oil guide plate delivers cooling oil to the cooling oil passage.

[0008] In the offset coaxial oil-cooled powertrain provided in this application embodiment, the shaft cavity of the motor shaft and the drive shaft are spaced radially along the drive motor to form a cooling oil passage for the drive motor. In other words, the drive motor is cooled using a concentric dual-axis oil circulation method involving the motor shaft and the drive shaft. The annular oil guide plate inside the motor end cover guides the cooling oil received from the internal flow channels of the motor end cover into the concentric dual-axis cooling oil passage of the oil-cooled powertrain, thereby improving the oil guiding performance of the annular oil guide plate and thus improving the heat dissipation performance of the drive motor. This is beneficial for enhancing the high power density and high torque density of the drive motor.

[0009] In one implementation, the annular oil guide plate includes an annular axial groove, the groove wall of which protrudes along the axial direction of the drive motor from the side of the annular oil guide plate facing the motor slot. The opening of the annular axial groove serves as an oil outlet, and the annular axial groove is used to embed cooling oil channels. Thus, the annular oil guide plate can output all the received coolant through the opening of its annular axial groove into the cooling oil channels, thereby improving the oil guiding performance of the annular oil guide plate's oil outlet.

[0010] In one implementation, the outer diameter of the radial annular axial groove along the drive motor is less than or equal to the diameter of the motor shaft cavity, and the inner diameter of the radial annular axial groove along the drive motor is greater than or equal to the diameter of the drive shaft. This reduces the leakage of coolant in the cooling oil passages, improves the cooling effect of the drive motor shaft, and thus improves the heat dissipation performance of the drive motor.

[0011] In one implementation, the outer circumferential surface of the annular oil guide plate includes a radial groove that connects to the annular axial groove. The opening of the radial groove serves as an oil inlet. The radial groove along the drive motor's central axis towards the annular oil guide plate gradually decreases in size along the circumferential direction of the drive motor. This results in lower flow resistance of the coolant within the radial groove of the annular oil guide plate, allowing the oil inlet of the annular oil guide plate to receive more coolant, thereby improving the oil guiding performance from the oil inlet to the oil outlet of the annular oil guide plate.

[0012] In one implementation, the annular oil guide disc has multiple protrusions on one end face facing the motor slot. These protrusions are arranged circumferentially along the drive motor, and the annular oil guide disc is fixed to the oil guide disc mounting slot via these protrusions. This prevents the annular oil guide disc from rotating circumferentially along the drive motor, avoids misalignment between the oil inlet of the annular oil guide disc and the oil outlet of the internal flow channel of the motor end cover, and thus improves the oil guiding performance of the annular oil guide disc's oil inlet.

[0013] In one implementation, the radial dimension of each of the multiple protrusions along the drive motor is larger than the circumferential dimension of each protrusion along the drive motor. This increases the contact area between each protrusion of the annular oil guide disc and the mounting groove, thereby increasing the abutment force between the annular oil guide disc and the mounting groove, and ultimately enhancing the robustness of the annular oil guide disc.

[0014] In one implementation, the bottom of the oil guide plate mounting groove includes multiple grooves arranged along the circumference of the drive motor. Each groove is used to embed one of a plurality of protrusions. Thus, the annular oil guide plate is fixed to the motor end cover by the protrusions on the annular oil guide plate and the grooves at the bottom of the oil guide plate mounting groove, preventing the annular oil guide plate from rotating along the circumference of the drive motor.

[0015] In one implementation, the opening of the oil guide plate mounting groove faces away from the motor slot along the axial direction of the drive motor, while the recessed direction of the oil guide plate mounting groove faces the motor slot along the axial direction of the drive motor. The motor end cover includes a through hole that penetrates the bottom of the oil guide plate mounting groove along the axial direction of the drive motor. One end of the drive shaft extends out of the motor slot through the through hole and the shaft cavity of the motor shaft to drive and connect to the differential. The other end of the drive shaft protrudes from the motor end cover. The diameter of the through hole along the radial direction of the drive motor is smaller than the diameter of the bottom of the oil guide plate mounting groove. Thus, the through hole of the motor end cover and the oil guide plate mounting groove can form a stepped structure. This stepped structure prevents the annular oil guide plate from moving towards the motor slot along the axial direction of the drive motor, avoiding misalignment between the oil inlet of the annular oil guide plate and the oil outlet of the internal flow channel of the motor end cover, thereby improving the oil guiding performance of the annular oil guide plate's oil inlet.

[0016] In one implementation, the side of the motor end cover away from the motor slot is also used to fix a bearing support 800. The bearing support 800 is used to fix the outer ring of one drive shaft bearing and the inner ring of the other drive shaft bearing to the other end of the drive shaft. Thus, the bearing support 800 can prevent the annular oil guide disc from moving axially away from the side facing the motor slot, avoiding misalignment between the oil inlet of the annular oil guide disc and the oil outlet of the internal flow channel of the motor end cover, thereby improving the oil guiding performance of the annular oil guide disc's oil inlet.

[0017] In one implementation, the oil guide plate mounting groove includes an oil outlet hole for connecting to the internal oil passages of the motor end cover. The oil inlet of the annular oil guide plate is used to receive cooling oil from the internal oil passages of the motor end cover through the oil outlet hole. The cross-sectional area of ​​the oil outlet hole is less than or equal to the cross-sectional area of ​​the oil inlet. This ensures that all the coolant output from the oil outlet hole of the motor end cover can be output to the oil inlet of the annular oil guide plate, thereby improving the oil guiding performance from the internal oil passages of the motor end cover to the oil inlet of the annular oil guide plate.

[0018] In one implementation, one end of the motor shaft is used to fix the rotor of the drive motor. This end of the motor shaft includes one or more sets of oil outlet holes, arranged axially along the drive motor. Each set of oil outlet holes connects the outer and inner circumferential surfaces of the motor shaft and supplies cooling oil to the rotor of the drive motor. This improves the cooling efficiency of the coolant in the cooling oil channels supplying cooling oil to the rotor of the drive motor, enhancing the cooling effect of the rotor and thus improving the heat dissipation performance of the drive motor.

[0019] In one implementation, the shaft hole of the rotor core of the drive motor includes multiple oil inlets, wherein a set of oil outlets connects the multiple oil inlets of the rotor core, and a set of oil outlets supplies cooling oil to the multiple oil inlets of the rotor core shaft hole. This improves the cooling efficiency of the coolant in the cooling oil channels supplying cooling oil to the rotor core of the drive motor, enhances the cooling effect of the rotor core, and ultimately improves the heat dissipation performance of the drive motor.

[0020] In one implementation, the rotor core and rotor end plate of the drive motor are arranged along the axial direction of the drive motor. The motor shaft passes through the shaft hole of the rotor end plate, which includes multiple oil inlets. One end face of the rotor end plate includes multiple oil outlets. Another set of oil outlets connects to the multiple oil inlets of the rotor end plate, and another set of oil outlets supplies cooling oil to the multiple oil inlets of the rotor end plate. The multiple oil outlets of the rotor end plate output coolant to cool the stator windings of the drive motor. This improves the cooling efficiency of the coolant in the cooling oil channels, which supplies cooling oil to the stator windings of the drive motor through the rotor end plate, thereby improving the cooling effect of the stator windings and ultimately enhancing the heat dissipation performance of the drive motor.

[0021] In one implementation, each set of oil outlet holes includes multiple oil outlet holes arranged circumferentially along the drive motor. This allows the powertrain to discharge coolant through these multiple outlet holes circumferentially along the drive motor during operation, resulting in more uniform heat dissipation of the drive motor along its circumference, preventing localized hot spots, and thus improving the drive motor's heat dissipation performance.

[0022] Secondly, embodiments of this application provide an electric vehicle comprising two front wheels, two rear wheels, and an oil-cooled powertrain as described in the first aspect and any implementation thereof. The oil-cooled powertrain is used to drive the two front wheels or the two rear wheels respectively via two half-shafts. The oil-cooled powertrain provided in this application embodiment achieves higher power density and higher torque density of the drive motor, thereby improving the driving range of the electric vehicle and enhancing the driving experience. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of an electric vehicle provided in an embodiment of this application.

[0024] Figure 2 This is a schematic diagram of a powertrain provided in an embodiment of this application.

[0025] Figure 3 This is a schematic diagram of the stator of a drive motor in a powertrain provided in an embodiment of this application.

[0026] Figure 4 This is a schematic diagram of the rotor of the drive motor in the oil-cooled powertrain provided in an embodiment of this application.

[0027] Figure 5 This is a schematic diagram of a reducer in an oil-cooled powertrain provided in an embodiment of this application.

[0028] Figure 6 This is another schematic diagram of an oil-cooled powertrain provided in an embodiment of this application.

[0029] Figure 7 This is a schematic diagram illustrating the fit between the motor shaft and the drive shaft provided in an embodiment of this application.

[0030] Figure 8 This is a schematic diagram of the housing of an oil-cooled powertrain provided in an embodiment of this application.

[0031] Figure 9 This is a schematic diagram of an integrated housing for an oil-cooled powertrain provided in an embodiment of this application.

[0032] Figure 10 This is a schematic diagram of a motor end cover provided in an embodiment of this application.

[0033] Figure 11 This is a schematic diagram of an annular oil guide plate provided in an embodiment of this application.

[0034] Figure 12 for Figure 11 The diagram shows a ring-shaped oil guide plate along direction A.

[0035] Figure 13and Figure 14 These are another schematic diagrams of the oil-cooled powertrain provided in the embodiments of this application. Detailed Implementation

[0036] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0037] The terms "equal to" or "equal to" in this application are not strictly equal or equal in the strict sense, but rather within the allowable error range. Similarly, "parallel" is not strictly parallel, but within the allowable error range. And "perpendicular" is not strictly perpendicular, but within the allowable error range.

[0038] In this embodiment, the same reference numeral denotes the same component or part. In this embodiment, for multiple identical parts, the reference numeral may only be used to label one of the parts as an example. The reference numerals also apply to other identical parts or components. Furthermore, the dimensions and sizes of the parts shown in the drawings are merely exemplary.

[0039] Figure 1 This is a schematic diagram of an electric vehicle provided in an embodiment of this application. The electric vehicles provided in this application include pure electric vehicles, hybrid electric vehicles, range-extended electric vehicles, plug-in hybrid electric vehicles, or new energy vehicles. Pure electric vehicles are also called pure electric vehicles / battery electric vehicles, or simply pure EVs / battery EVs. Hybrid electric vehicles are also called hybrid electric vehicles, or simply HEVs. Range-extended electric vehicles are also called range-extended electric vehicles, or simply REEVs. Plug-in hybrid electric vehicles are also called plug-in hybrid electric vehicles, or simply PHEVs. New energy vehicles are also called newenergy vehicles, or simply NEVs.

[0040] like Figure 1 As shown, the electric vehicle 1 includes an oil-cooled powertrain 10 and a power battery 20. The oil-cooled powertrain 10 receives power from the power battery 20 and converts electrical energy into mechanical energy to drive the wheels of the electric vehicle 1.

[0041] In one embodiment, the electric vehicle 1 includes two oil-cooled power assemblies 10, one of which drives the two front wheels of the electric vehicle 1, and the other drives the two rear wheels of the electric vehicle 1. In another embodiment, the electric vehicle 1 includes four oil-cooled power assemblies 10, which drive the four wheels of the electric vehicle 1 respectively.

[0042] like Figure 1 As shown, the electric vehicle 1 also includes a power module 40. The power module 40 is used to receive power from an external power source 50 to charge the power battery 20. In one embodiment, the external power source 50 is an AC power grid, an AC charging station, or a DC charging station. The power module 40 includes at least one of a DC charger or an AC charger.

[0043] This application also provides an oil-cooled powertrain. In one embodiment, the oil-cooled powertrain includes a drive motor for driving the wheels of an electric vehicle.

[0044] like Figure 1 As shown, the oil-cooled powertrain 10 provided in this embodiment includes a drive motor 100, which is used to drive the wheels of the electric vehicle 1.

[0045] In one embodiment, the oil-cooled powertrain further includes a reduction gear, through which the drive motor drives the wheels of the electric vehicle.

[0046] like Figure 1 As shown, the oil-cooled powertrain 10 provided in this application embodiment also includes a reducer 200, through which the drive motor 100 drives the wheels of the electric vehicle 1.

[0047] In one embodiment, the oil-cooled powertrain further includes a motor controller. The motor controller is used to control the drive motor to drive the wheels of the electric vehicle.

[0048] like Figure 1 As shown, the oil-cooled powertrain 10 provided in this embodiment of the application also includes a motor controller 300. The motor controller 300 is used to receive the DC power output from the power battery 20, convert the DC power output from the power battery 20 into AC power, and control the drive motor 100 to drive the wheels of the electric vehicle 1.

[0049] Figure 2 This is a schematic diagram of an oil-cooled powertrain provided in an embodiment of this application. Figure 2As shown, the oil-cooled powertrain 10 includes a drive motor 100. The drive motor 100 includes a stator 110, a rotor 120, and a motor shaft 130. The motor shaft 130 is used to fix the rotor 120.

[0050] In one embodiment, such as Figure 2 As shown, the oil-cooled powertrain 10 also includes a reducer 200, through which the drive motor 100 drives the wheels of the electric vehicle 1.

[0051] In one embodiment, such as Figure 2 As shown, the oil-cooled powertrain 10 also includes a motor controller 300, which converts the DC power output from the power battery 20 into AC power. The motor controller 300 outputs three-phase AC power to the stator windings of the stator 110 of the drive motor 100, thereby controlling the rotor 120 of the drive motor 100 to rotate relative to the stator 110, and the rotor 120 drives the motor shaft 130 to rotate.

[0052] In this embodiment, the axial direction of the drive motor 100 can be understood as the axial direction of the motor shaft 130 of the drive motor 100, the axial direction of the stator core 111 of the drive motor 100, the axial direction of the reducer 200, and the axial direction of the oil-cooled power assembly 10.

[0053] Figure 3 This is a schematic diagram of the stator of a drive motor in an oil-cooled powertrain provided in an embodiment of this application. Figure 3 As shown, the stator 110 of the drive motor 100 includes a stator core 111 and a stator winding 112. The stator winding 112 includes two winding coils 1121 and 1122, which are respectively exposed on both sides of the stator core 111 along the axial direction of the drive motor 100.

[0054] In this embodiment, the axial direction of the drive motor 100 can be understood as the axial direction of the motor shaft 130 of the drive motor 100, the axial direction of the stator core 111 of the drive motor 100, the axial direction of the reducer 200, and the axial direction of the oil-cooled power assembly 10.

[0055] In one embodiment, the stator winding 112 includes three-phase windings and three winding busbars 1123. Each phase winding in the three-phase windings includes multiple sets of windings connected in parallel, and the multiple sets of windings connected in parallel in each phase winding receive one phase of alternating current through a winding busbar 1123.

[0056] Figure 4 This is a schematic diagram of the rotor of the drive motor in an oil-cooled powertrain provided in an embodiment of this application. Figure 4As shown, the rotor 120 of the drive motor 100 includes a rotor core 121 and a rotor end plate 122, which are arranged along the axial direction of the drive motor 100.

[0057] like Figure 4 As shown, the rotor core 121 includes a shaft hole 1211, which extends through the rotor core 121 along the axial direction of the drive motor 100. The motor shaft 130 passes through the shaft hole 1211 of the rotor core 121 and is used to fix the rotor core 121.

[0058] In one embodiment, the rotor core 121 includes a plurality of rotor laminations arranged along the axial direction of the drive motor 100. Each rotor lamination includes a shaft hole, and the plurality of shaft holes of the plurality of rotor laminations are connected along the axial direction of the drive motor 100 to form a shaft hole 1211 of the rotor core 121.

[0059] like Figure 4 As shown, the rotor end plate 122 includes a shaft hole 1221, which extends through the rotor end plate 122 along the axial direction of the drive motor 100. The motor shaft 130 passes through the shaft hole 1221 of the rotor end plate 122.

[0060] In one embodiment, the rotor 120 includes two rotor end plates 122, which are arranged on both sides of the rotor core 121 along the axial direction of the drive motor 100.

[0061] In one embodiment, the rotor 120 of the drive motor 100 further includes a plurality of magnets, and the rotor core 121 further includes a plurality of magnet slots, each magnet slot being used to accommodate at least one magnet. The stator windings of the stator 110 of the drive motor 100 are connected to three-phase alternating current, and the rotor core 121 of the drive motor 100 rotates relative to the stator 110, driving the motor shaft 130 to rotate.

[0062] Figure 5 This is a schematic diagram of a reducer in an oil-cooled powertrain provided in an embodiment of this application. Figure 5 As shown, the reducer 200 in the oil-cooled powertrain 10 includes a drive shaft 210, a primary gear set 220, a secondary gear set 230, and a differential 240. The drive shaft 210 of the reducer 200 is arranged parallel to the motor shaft 130 of the drive motor 100, i.e., the drive shaft 210 of the reducer 200 and the motor shaft 130 of the drive motor 100 are offset from each other. The primary gear set 220 of the reducer 200 is used to drive the drive shaft 210 of the reducer 200 and the motor shaft 130 of the drive motor 100. The drive shaft 210 of the reducer 200 is used to drive the differential 240 via the secondary gear set 230. The differential 240 is used to drive one of the two wheels of the electric vehicle 1.

[0063] like Figure 5 As shown, the primary gear set 220 includes a driving gear 221 and a driven gear 222. The driving gear 221 of the primary gear set 220 is fixed to the motor shaft 130, and the driven gear 222 of the primary gear set 220 is fixed to the transmission shaft 210. The driving gear 221 and the driven gear 222 of the primary gear set 220 mesh to drive the rotation of the motor shaft 130 of the motor 100, which in turn drives the transmission shaft 210 of the reducer 200 to rotate.

[0064] In one embodiment, the drive wheel 221 of the primary gear set 220 and the motor shaft 130 are integrally formed. For example, the drive wheel 221 of the primary gear set 220 is directly machined onto the motor shaft 130 to form a gear shaft, thereby obtaining an integral structure of the drive wheel 221 of the primary gear set 220 and the motor shaft 130.

[0065] like Figure 5 As shown, the secondary gear set 230 includes a driving gear 231 and a driven gear 232. The driving gear 231 of the secondary gear set 230 is fixed to the drive shaft 210, and the driven gear 222 of the secondary gear set 230 is used to drive the differential 240. The driving gear 221 and driven gear 222 of the secondary gear set 230 mesh, and the rotation of the drive shaft 210 of the reducer 200 drives the differential 240 to rotate.

[0066] like Figure 5 As shown, the reducer 200 also includes a pair of bearings 250 for drivingly connecting the reducer 200 to the drive shaft 210. In one embodiment, the inner ring of each bearing 250 is used to fix it to the drive shaft 210.

[0067] Figure 6 This is another schematic diagram of an oil-cooled powertrain provided in an embodiment of this application. (See diagram below.) Figure 6 As shown, the oil-cooled powertrain 10 also includes a drive shaft 400, and the transmission shaft 210 of the reducer 200 is also used to drive the drive shaft 400 through a secondary gear set 230. The drive shaft 400 is used to drive the other wheel of the two wheels of the electric vehicle 1.

[0068] Figure 7 This is a schematic diagram illustrating the fit between the motor shaft and the drive shaft provided in an embodiment of this application. Figure 7 As shown, the shaft cavity of the motor shaft 130 is used to accommodate the drive shaft 400, meaning the drive shaft 400 and the motor shaft 130 of the drive motor 100 are coaxially arranged. Furthermore, the shaft cavity of the motor shaft 130 and the drive shaft 400 form a cooling oil passage 600 at a radial distance from the drive motor 100. In other words, the drive motor 100 is cooled using a concentric dual-axis oil circulation method involving the motor shaft 130 and the drive shaft 400.

[0069] In one embodiment, the drive shaft 400 may also be referred to as an adapter half-shaft.

[0070] Combination Figure 6 As shown, in the oil-cooled power assembly 10 provided in this embodiment, one end of the motor shaft 130 is used to fix the rotor 120 of the drive motor 100, and the other end of the motor shaft 130 is used to fix the drive wheel 221 of the first-stage gear set 220. That is, the motor shaft 130 of the drive motor 100 serves as both the transmission shaft of the drive motor 100 and the shaft that drives the drive wheel 221 of the first-stage gear set 220 of the reducer 200 to rotate. The motor shaft 130 of the drive motor 100 and the input shaft of the reducer 200 are set to the same shaft. In addition, the motor shaft 130 of the drive motor 100 and the transmission shaft 210 of the reducer 200 are arranged in parallel. Therefore, the oil-cooled power assembly 10 provided in this embodiment can also be called an offset coaxial oil-cooled power assembly 10.

[0071] In this embodiment, the radial direction of the drive motor 100 can be understood as the radial direction of the motor shaft 130 of the drive motor 100, the radial direction of the stator core 111 of the drive motor 100, the radial direction of the reducer 200, and the radial direction of the power assembly 10.

[0072] Figure 8 This is a schematic diagram of the housing of an oil-cooled powertrain provided in an embodiment of this application. Figure 9 This is a schematic diagram of an integrated housing for an oil-cooled powertrain provided in an embodiment of this application. Figure 8 As shown, the housing of the oil-cooled powertrain 10 includes an integrated housing 500, such as... Figure 9 As shown, the integrated housing 500 includes a motor slot G1 for fixing and accommodating the stator 110 of the drive motor 100.

[0073] One end of the motor shaft 130 of the drive motor 100 is accommodated in the motor slot G1, and the other end extends out of the motor slot G1 to fix the drive wheel 221 of the first-stage gear set 220. In one embodiment, as... Figure 9 As shown, the integrated housing 500 also includes a shaft hole 6010, which penetrates the bottom of the motor slot G1 along the axial direction of the drive motor 100. The shaft hole 6010 is used to avoid the motor shaft 130, that is, one end of the motor shaft 130 extends into the motor slot G1, and the other end of the motor shaft 130 extends out of the motor slot G1 through the shaft hole 6010.

[0074] In addition, one end of the drive shaft 400 extends out of the motor slot G1 through the shaft cavity of the motor shaft 130 and is connected to the differential 240 of the reducer 200 for transmission. The other end of the drive shaft 400 is used to connect to the other wheel of the two wheels of the electric vehicle 1 for transmission.

[0075] like Figure 8 As shown, the housing of the oil-cooled powertrain 10 also includes a motor end cover 510, which is used to enclose the motor slot G1 to form a motor receiving cavity.

[0076] In some embodiments, such as Figure 9 As shown, the integrated housing 500 also includes a reducer slot G2. The reducer slot G2 is used to accommodate the primary gear set 220 and the secondary gear set 230 of the reducer 200. In one embodiment, the reducer slot G2 is also used to accommodate the differential 240 of the reducer 200.

[0077] In some embodiments, the integrated housing 500 also includes a reducer end cover for enclosing the reducer groove G2 to form a reducer receiving cavity.

[0078] In one embodiment, the orientation of the slot opening of the motor slot G1 is opposite to the orientation of the slot opening of the reducer slot G2 along the axial direction of the drive motor 100.

[0079] In one embodiment, such as Figure 9 As shown, the shaft hole 6010 of the integrated housing 500 connects the motor slot G1 and the reducer slot G2 along the axial direction of the drive motor 100. Thus, one end of the motor shaft 130 extends into the motor slot G1, and the other end of the motor shaft 130 passes through the shaft hole 6010 and extends into the reducer slot G2.

[0080] Figure 10 This is a schematic diagram of a motor end cover provided in an embodiment of this application. Figure 10 As shown, the motor end cover 510 also includes an oil guide plate mounting groove 5101, which is used to mount an annular oil guide plate 700. The motor shaft 130 of the drive motor 100 and the annular oil guide plate 700 are arranged along the axial direction of the drive motor 100. The annular oil guide plate 700 is used to receive cooling oil from the internal oil passage of the motor end cover 510 and to transport the received cooling oil to the cooling oil passage 600.

[0081] In the oil-cooled powertrain 10 provided in this embodiment, the cooling oil received from the internal flow channel of the motor end cover 510 is guided by the annular oil guide plate 700 inside the motor end cover 510 into the cooling oil channel 600 formed by the concentric dual shafts of the motor shaft 130 and the drive shaft 400. This improves the oil guiding performance of the annular oil guide plate 700, thereby improving the heat dissipation performance of the drive motor 100, which is beneficial to improving the high power density and high torque density of the drive motor 100. This, in turn, helps to increase the driving range of the electric vehicle 1 and improve the driving experience of the electric vehicle 1.

[0082] In one embodiment, the stator winding busbar 1123 of the stator winding 112 of the stator 110 of the drive motor 100 is distributed on the side of the stator core 111 away from the motor end cover 510. Thus, the connecting copper busbar for the drive motor 100 to receive the three-phase AC power from the motor controller 300 through the winding busbar 1123 can be deployed on one side of the bottom of the motor slot G1, thereby ensuring that the connecting copper busbar does not affect the oil guiding performance of the annular oil guide plate 700 in the motor end cover 510.

[0083] Figure 11 This is a schematic diagram of an annular oil guide plate provided in an embodiment of this application. Figure 11 As shown, the annular oil guide plate 700 includes an oil inlet 701 and an oil outlet 702. The oil inlet 701 of the annular oil guide plate 700 is oriented along the radial direction of the drive motor 100, and the oil outlet 702 of the annular oil guide plate 700 is oriented along the axial direction of the drive motor 100. The oil inlet 701 of the annular oil guide plate 700 is used to receive cooling oil output from the internal flow channel of the motor end cover 510, and the oil outlet 702 of the oil guide plate is used to deliver cooling oil to the cooling oil channel 600.

[0084] In one embodiment, such as Figure 10 As shown, the oil guide plate mounting groove 5101 includes an oil outlet hole 5102, which is used to connect to the internal oil passage of the motor end cover 510. The oil inlet 701 of the annular oil guide plate 700 is used to receive the cooling oil from the internal oil passage of the motor end cover 510 through the oil outlet hole 5102 of the oil guide plate mounting groove 5101.

[0085] In one embodiment, the cross-sectional area of ​​the oil outlet 5102 of the oil guide plate mounting groove 5101 is less than or equal to the cross-sectional area of ​​the oil inlet 701 of the annular oil guide plate 700. Therefore, all the coolant output from the oil outlet 5102 of the motor end cover 510 can be output to the oil inlet 701 of the annular oil guide plate 700, thereby improving the oil guiding performance of the internal oil passages of the motor end cover 510 to the oil inlet 701 of the annular oil guide plate 700.

[0086] like Figure 11 As shown, the annular oil guide plate 700 includes an annular axial groove 710, and the groove opening of the annular axial groove 710 is the oil outlet 702 of the annular oil guide plate 700, so that the oil outlet 702 of the annular oil guide plate 700 is oriented towards the motor groove G1 along the axial direction of the drive motor 100.

[0087] like Figure 11 As shown, the groove wall of the annular axial groove 710 protrudes along the axial direction of the drive motor 100 from the side of the annular oil guide plate 700 facing the motor groove G1. The annular axial groove 710 is used to embed into the cooling oil passage 600. Thus, the annular oil guide plate 700 can output all the received coolant through the groove opening of the annular axial groove 710 to the cooling oil passage 600, thereby improving the oil guiding performance of the oil outlet of the annular oil guide plate 700.

[0088] Figure 12 for Figure 11 The diagram shows a ring-shaped oil guide plate along direction A. In one embodiment, as shown... Figure 12 As shown, the outer diameter D1 of the radial annular axial groove 710 of the drive motor 100 is less than or equal to the diameter D of the shaft cavity of the motor shaft 130, and the inner diameter D2 of the radial annular axial groove 710 of the drive motor 100 is greater than or equal to the diameter of the drive shaft 400. This reduces the leakage of coolant in the cooling oil passage 600, improves the cooling effect of the motor shaft 130 of the drive motor 100, and thus improves the heat dissipation performance of the drive motor 100.

[0089] like Figure 11 As shown, the outer peripheral surface of the annular oil guide plate 700 includes a radial groove 720, which is used to connect the annular axial groove 710. The groove opening of the radial groove 720 is the oil inlet 701 of the annular oil guide plate 700.

[0090] In one embodiment, along the radial direction of the drive motor 100 facing the central axis of the annular oil guide plate 700, the radial groove 720 gradually decreases in size along the circumferential direction of the drive motor 100. For example... Figure 12 As shown, the radial groove 720 includes two groove walls 721 and 722 arranged opposite each other along the circumference of the drive motor 100. Along the x-direction, the distance D3 between the two groove walls 721 and 722 of the radial groove 720 gradually decreases. Figure 12 The x-direction is the radial direction of the drive motor 100 along the central axis of the annular oil guide plate 700. As a result, the flow resistance of the coolant in the radial groove 720 of the annular oil guide plate 700 is small, allowing the oil inlet of the annular oil guide plate 700 to receive more coolant, thereby improving the oil guiding performance from the oil inlet 701 of the annular oil guide plate 700 to the oil outlet 702 of the annular oil guide plate 700.

[0091] In this embodiment, the circumferential direction of the drive motor 100 can be understood as the circumferential direction of the motor shaft 130 of the drive motor 100, the circumferential direction of the stator core 111 of the drive motor 100, the circumferential direction of the reducer 200, and the circumferential direction of the power assembly 10.

[0092] In one embodiment, such as Figure 11As shown, the annular oil guide plate 700 has multiple protrusions 7301 on one end face 730 facing the motor slot G1, which are arranged circumferentially along the drive motor 100. The annular oil guide plate 700 is fixed to the oil guide plate mounting slot 5101 circumferentially along the drive motor 100 by the multiple protrusions 7301. This prevents the annular oil guide plate 700 from rotating circumferentially along the drive motor 100, avoids misalignment between the oil inlet of the annular oil guide plate 700 and the oil outlet 5102 of the internal flow channel of the motor end cover 510, and thus improves the oil guiding performance of the oil inlet 701 of the annular oil guide plate 700.

[0093] like Figure 10 As shown, the bottom of the oil guide plate mounting groove 5101 includes multiple grooves 5103, which are arranged circumferentially along the drive motor 100. (This is in conjunction with...) Figure 10 and Figure 11 Each of the multiple grooves 5103 is used to embed one of the multiple protrusions 7301. Thus, the annular oil guide plate 700 is fixed to the motor end cover 510 by the protrusions 7301 on the annular oil guide plate 700 and the grooves 5103 at the bottom of the oil guide plate mounting groove 5101, so as to prevent the annular oil guide plate 700 from rotating along the circumference of the drive motor 100.

[0094] In one embodiment, the radial dimension of each of the plurality of protrusions 7301 along the drive motor 100 is larger than the circumferential dimension of each of the protrusions 7301 along the drive motor 100. For example... Figure 11 As shown, the radial dimension of each protrusion 7301 along the drive motor 100 is W1, and the circumferential dimension of each protrusion 7301 along the drive motor 100 is W2. This increases the contact area between each protrusion 7301 of the annular oil guide plate 700 and the oil guide plate mounting groove, thereby increasing the abutment force between the annular oil guide plate 700 and the oil guide plate mounting groove, and further increasing the robustness of the annular oil guide plate 700 to prevent rotation of the annular oil guide plate 700 along the circumferential direction of the drive motor 100.

[0095] In one embodiment, the opening of the oil guide plate mounting groove 5101 is oriented away from the motor groove G1 along the axial direction of the drive motor 100, and the recess direction of the oil guide plate mounting groove 5101 is oriented towards the motor groove G1 along the axial direction of the drive motor 100.

[0096] like Figure 10 As shown, the motor end cover 510 also includes a through hole 5104, which passes through the bottom of the oil guide plate mounting groove 5101 along the axial direction of the drive motor 100. One end of the drive shaft 400 is used to extend out of the motor groove G1 through the through hole 5104 and the shaft cavity of the motor shaft 130 to drive the differential 240 of the reducer 200. The other end of the drive shaft 400 is exposed in the motor end cover 510.

[0097] In one embodiment, the diameter of the radial through hole 5104 along the drive motor 100 is smaller than the diameter of the bottom of the oil guide plate mounting groove 5101. Thus, the through hole 5104 of the motor end cover 510 and the oil guide plate mounting groove 5101 can form a stepped structure. This stepped structure prevents the annular oil guide plate 700 from moving axially toward the motor groove G1 along the drive motor 100, avoiding misalignment between the oil inlet 701 of the annular oil guide plate 700 and the oil outlet 5102 of the internal flow channel of the motor end cover 510, thereby improving the oil guiding performance of the oil inlet 701 of the annular oil guide plate 700.

[0098] Figure 13 and Figure 14 These are another schematic diagrams of the oil-cooled powertrain provided in the embodiments of this application. In one embodiment, the side of the motor end cover 510 away from the motor slot G1 is also used to fix the bearing support 800. The bearing support 800 is used to fix the outer ring of one drive shaft bearing 510 of the drive shaft 400, and the inner ring of one drive shaft bearing 510 of the drive shaft 400 is used to fix the other end of the drive shaft 400 exposed in the motor end cover 510. Thus, the bearing support 800 can prevent the annular oil guide plate 700 from moving away from the side facing the motor slot G1 along the axial direction of the drive motor 100, and avoid misalignment between the oil inlet 701 of the annular oil guide plate 700 and the oil outlet 5102 of the internal flow channel of the motor end cover 510, thereby improving the oil guiding performance of the oil inlet 701 of the annular oil guide plate 700.

[0099] The motor shaft 130, used to fix the rotor 120 of the drive motor 100, includes one or more sets of oil outlet holes at one end. These multiple sets of oil outlet holes are arranged along the axial direction of the drive motor 100. Each set of oil outlet holes connects the outer and inner circumferential surfaces of the motor shaft 130 and supplies cooling oil to the rotor 120 of the drive motor 100. This improves the cooling efficiency of the coolant in the cooling oil passage 600 in supplying cooling oil to the rotor 120 of the drive motor 100, enhances the cooling effect of the rotor of the drive motor 100, and ultimately improves the heat dissipation performance of the drive motor 100.

[0100] In one embodiment, each set of oil outlet holes includes multiple oil outlet holes arranged circumferentially along the drive motor 100. Thus, during operation, the powertrain can eject coolant through these multiple oil outlet holes along the circumferential direction of the drive motor 100, resulting in more uniform heat dissipation of the drive motor 100 along its circumference, avoiding localized hot spots, and thereby improving the heat dissipation performance of the drive motor 100.

[0101] In one embodiment, the oil outlet of the motor shaft 130 is used to deliver coolant to the cooling oil passage of the rotor core 121 of the rotor 120 of the drive motor 100, thereby cooling the rotor core 121 of the drive motor 100.

[0102] like Figure 13 As shown, the shaft hole 1211 of the rotor core 121 of the rotor 120 of the drive motor 100 includes multiple oil inlets 1212. A set of oil outlet holes 131 of the motor shaft 130 is used to connect the multiple oil inlets 1212 of the rotor core 121, and the set of oil outlet holes 131 of the motor shaft 130 is used to supply cooling oil to the multiple oil inlets 1212 of the shaft hole 1211 of the rotor core 121. This improves the cooling efficiency of the coolant in the cooling oil passage 600 in supplying cooling oil to the rotor core 121 of the rotor 120 of the drive motor 100, improves the cooling effect of the rotor core 121 of the drive motor 100, and thus improves the heat dissipation performance of the drive motor 100.

[0103] In one embodiment, such as Figure 13 As shown, the rotor core 121 of the rotor 120 of the drive motor 100 also includes multiple axial oil passages 1213. These multiple axial oil passages 1213 extend through the rotor core 121 of the rotor 120 of the drive motor 100 along the axial direction of the drive motor 100, and are arranged circumferentially along the drive motor 100. Each axial oil passage 1213 of the rotor core 121 of the drive motor 100 is used to connect to an oil inlet 1212 of the shaft hole 1211 of the rotor core 121. Thus, the coolant flowing into the multiple oil inlets 1212 of the shaft hole 1211 of the rotor core 121 can flow into each axial oil passage 1213 of the rotor core 121 of the drive motor 100, improving the cooling effect of the rotor core 121 of the drive motor 100, and thereby improving the heat dissipation performance of the drive motor 100.

[0104] In one embodiment, such as Figure 13 As shown, the rotor core 121 includes two first sub-rotor cores 1214 and one second sub-rotor core 1215. The two first sub-rotor cores 1214 are arranged on both sides of the second sub-rotor core 1215 along the axial direction of the drive motor 100. Each first sub-rotor core 1214 and each second sub-rotor core 1215 includes at least one rotor lamination. The shaft hole of each rotor lamination in the second sub-rotor core 1215 includes multiple grooves, and the slots of the multiple grooves in each rotor lamination in the second sub-rotor core 1215 are multiple oil inlets 1212 of the shaft hole 1211 of the rotor core 121.

[0105] In one embodiment, each rotor lamination of the rotor core 121 includes multiple oil passages, which are connected along the axial direction of the drive motor 100 to form an axial oil passage 1213. Furthermore, the two first sub-rotor cores 1214 include the same number of rotor laminations. This allows the coolant in the multiple oil inlets 1212 of the shaft hole 1211 of the rotor core 121 to flow evenly into the two first sub-rotor cores 1214, cooling them. This improves the cooling effect of the rotor core 121 of the drive motor 100, thereby enhancing the heat dissipation performance of the drive motor 100.

[0106] In one embodiment, such as Figure 13 As shown, one end face of the rotor end plate 122 includes multiple oil outlets 1223. These outlets connect to multiple axial oil passages 1213 of the rotor core 121 of the rotor 120 of the drive motor 100 and output coolant to cool the stator windings 112 of the stator 110 of the drive motor 100. This improves the cooling effect of the stator windings 112 of the drive motor 100, thereby enhancing the heat dissipation performance of the drive motor 100.

[0107] In one embodiment, the oil outlet of the motor shaft 130 is used to deliver coolant to the cooling oil passage of the rotor end plate 122 of the rotor 120 of the drive motor 100, so that the coolant in the cooling oil passage of the rotor end plate 122 of the rotor 120 of the drive motor 100 is sprayed onto the stator winding 112 of the stator 110 of the drive motor 100, thereby cooling the stator winding 112 of the stator 110 of the drive motor 100.

[0108] like Figure 14 As shown, the shaft hole 1221 of the rotor end plate 122 includes multiple oil inlets 1222, and one end face of the rotor end plate 122 includes multiple oil outlets 1223. The multiple oil inlets 1222 of the rotor end plate 122 are used to connect with the multiple oil inlets 1222 of the rotor end plate 122. Another set of oil outlet holes 132 of the motor shaft 130 is used to connect with the multiple oil inlets 1223 of the rotor end plate 122. The other set of oil outlet holes 132 of the motor shaft 130 is used to supply cooling oil to the multiple oil inlets 1222 of the rotor end plate 122, and the multiple oil outlet holes 1223 of the rotor end plate 122 are used to output coolant to cool the stator winding 112 of the stator 110 of the drive motor 100. This improves the cooling effect of the stator winding 112 of the drive motor 100, thereby improving the heat dissipation performance of the drive motor 100.

[0109] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An oil-cooled powertrain, characterized in that, The housing of the oil-cooled powertrain includes a motor slot and a motor end cover. The motor slot is used to accommodate and fix the stator of the drive motor of the oil-cooled powertrain. The motor end cover is used to enclose the motor slot. One end of the motor shaft of the drive motor is used to extend into the motor slot, and the other end of the motor shaft is used to extend out of the motor slot and drive the transmission shaft of the reducer. The motor shaft and the transmission shaft are arranged in parallel. The transmission shaft is used to drive the differential of the reducer. The oil-cooled powertrain includes a drive shaft. One end of the drive shaft extends out of the motor slot through the shaft cavity of the motor shaft and drives the differential. The other end of the drive shaft is used to drive the wheel of the electric vehicle. The shaft cavity of the motor shaft and the drive shaft are spaced radially along the drive motor to form a cooling oil passage. The motor end cover includes an oil guide plate mounting groove for mounting an annular oil guide plate. The motor shaft and the annular oil guide plate are arranged axially along the drive motor. The annular oil guide plate includes an oil inlet and an oil outlet. The oil inlet is oriented radially along the drive motor, and the oil outlet is oriented axially along the drive motor. The oil inlet of the annular oil guide plate is used to receive cooling oil output from the internal flow channel of the motor end cover, and the oil outlet of the annular oil guide plate is used to deliver cooling oil to the cooling oil channel.

2. The oil-cooled powertrain according to claim 1, characterized in that, The annular oil guide plate includes an annular axial groove, the groove wall of which protrudes along the axial direction of the drive motor from the side of the annular oil guide plate facing the motor groove, wherein: The groove of the annular axial groove is the oil outlet, and the annular axial groove is used to embed the cooling oil passage.

3. The oil-cooled powertrain according to claim 2, characterized in that, The outer diameter of the annular axial groove along the radial direction of the drive motor is less than or equal to the diameter of the shaft cavity of the motor shaft, and the inner diameter of the annular axial groove along the radial direction of the drive motor is greater than or equal to the diameter of the drive shaft.

4. The oil-cooled powertrain according to claim 2 or 3, characterized in that, The outer circumferential surface of the annular oil guide plate includes a radial groove, which connects to the annular axial groove. The opening of the radial groove serves as the oil inlet. The radial groove along the radial direction of the drive motor, which is oriented toward the central axis of the annular oil guide plate, gradually decreases in size along the circumferential direction of the drive motor.

5. The oil-cooled powertrain according to any one of claims 1 to 4, characterized in that, The annular oil guide plate has multiple protrusions on one end face facing the motor slot. The multiple protrusions are arranged circumferentially along the drive motor, and the annular oil guide plate is fixed to the oil guide plate mounting slot along the circumferential direction of the drive motor by the multiple protrusions.

6. The oil-cooled powertrain according to claim 5, characterized in that, The radial dimension of each of the plurality of protrusions along the drive motor is greater than the circumferential dimension of each of the protrusions along the drive motor.

7. The oil-cooled powertrain according to claim 5 or 6, characterized in that, The bottom of the oil guide plate mounting groove includes multiple grooves arranged along the circumference of the drive motor, and each of the multiple grooves is used to embed one of the multiple protrusions.

8. The oil-cooled powertrain according to claim 7, characterized in that, The groove opening of the oil guide plate mounting groove faces away from the motor groove along the axial direction of the drive motor, and the recess direction of the oil guide plate mounting groove faces the motor groove along the axial direction of the drive motor. The motor end cover includes a through hole that penetrates the bottom of the oil guide plate mounting groove along the axial direction of the drive motor. One end of the drive shaft extends out of the motor groove through the through hole and the shaft cavity of the motor shaft to drive and connect to the differential. The other end of the drive shaft protrudes from the motor end cover. Wherein: The diameter of the through hole along the radial direction of the drive motor is smaller than the diameter of the bottom of the oil guide plate mounting groove.

9. The oil-cooled powertrain according to claim 7 or 8, characterized in that, The side of the motor end cover away from the motor slot is also used to fix a bearing support. The bearing support is used to fix the outer ring of one drive shaft bearing of the drive shaft, and the inner ring of the one drive shaft bearing is used to fix the other end of the drive shaft.

10. The oil-cooled powertrain according to any one of claims 1 to 9, characterized in that, The oil guide plate mounting groove includes an oil outlet hole, which is used to connect to the internal oil passage of the motor end cover. The oil inlet is used to receive cooling oil from the internal oil passage of the motor end cover through the oil outlet hole, wherein: The cross-sectional area of ​​the oil outlet is less than or equal to the cross-sectional area of ​​the oil inlet.

11. The oil-cooled powertrain according to any one of claims 1 to 10, characterized in that, One end of the motor shaft is used to fix the rotor of the drive motor. The one end of the motor shaft includes one or more sets of oil outlet holes. The multiple sets of oil outlet holes are arranged along the axial direction of the drive motor. Each set of oil outlet holes is used to connect the outer circumferential surface and the inner circumferential surface of the motor shaft and to deliver cooling oil to the rotor of the drive motor.

12. The oil-cooled powertrain according to claim 11, characterized in that, The rotor core of the drive motor has a shaft hole that includes multiple oil inlets, wherein: A set of oil outlet holes is used to connect the plurality of oil inlets of the rotor core, and the set of oil outlet holes is used to deliver cooling oil to the plurality of oil inlets of the shaft hole of the rotor core.

13. The oil-cooled powertrain according to claim 11 or 12, characterized in that, The rotor core and rotor end plate of the drive motor are arranged along the axial direction of the drive motor. The motor shaft passes through the shaft hole of the rotor end plate, the shaft hole of the rotor end plate includes multiple oil inlets, and one end face of the rotor end plate includes multiple oil outlets, wherein: Another set of oil outlet holes is used to connect to the plurality of oil inlets of the rotor end plate, and the other set of oil outlet holes is used to deliver cooling oil to the plurality of oil inlets of the rotor end plate. The plurality of oil outlet holes of the rotor end plate are used to output coolant to cool the stator windings of the stator of the drive motor.

14. The oil-cooled powertrain according to any one of claims 11 to 13, characterized in that, Each group of oil outlet holes includes multiple oil outlet holes, which are arranged circumferentially along the drive motor.

15. An electric vehicle, characterized in that, The electric vehicle includes two front wheels, two rear wheels, and an oil-cooled powertrain as described in any one of claims 1-14, the oil-cooled powertrain being used to drive the two front wheels or the two rear wheels respectively via two half-shafts.

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