Cooling and lubricating arrangement for an electric axle drive system, electric axle drive system and vehicle

Abstract

The application discloses a cooling and lubricating structure of an electric axle driving system, the electric axle driving system and a car. The cooling and lubricating structure of the electric axle driving system is arranged in an electric axle driving system with a motor, a reduction gearbox and a differential. The motor comprises a hollow motor shaft, a long half shaft passes through the motor shaft, the reduction gearbox contains oil, the differential is provided with a half shaft gear, the long half shaft and the half shaft gear are connected through a spline, an oil seal is arranged between the motor shaft and the long half shaft away from the reduction gearbox, the oil in the reduction gearbox enters the area between the motor shaft and the long half shaft to cool the motor shaft, and enters the spline connecting area connecting the long half shaft and the half shaft gear to lubricate the spline connection. The oil effectively absorbs the heat generated by the motor, improves the cooling performance of the motor, and lubricates the spline connection area to improve the wear resistance and service life of the spline connection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobiles, in particular to a cooling and lubricating structure of an electric axle drive system for a pure electric vehicle and a hybrid electric vehicle, and an electric axle drive system and an automobile comprising the same. BACKGROUND

[0002] The electric drive mode for a pure electric vehicle and a hybrid electric vehicle includes a central motor drive mode, which reduces the size and mass of mechanical transmission devices. One arrangement of the central motor drive mode is to integrate an electric motor, a fixed-ratio reducer and a differential into one, and two half shafts connect two drive wheels, which is referred to as an electric axle drive system (eAxle drive system).

[0003] Referring to Figure 1 Fig. 1 is a cross-sectional view of a cooling and lubricating structure 100 of a known electric axle drive system, which is provided with an electric motor, a reducer and a differential. The reducer is a fixed-ratio reducer, which is more similar to a single-speed reducer in a narrow sense. The electric motor includes an electric motor housing 10, an electric motor stator 11, an electric motor rotor 12, a water cooling jacket 13 and an electric motor shaft 14. The electric motor shaft 14 is a hollow shaft, and a long half shaft 15 passes through the hollow electric motor shaft 14. The electric motor shaft 14 and an input shaft provided on the reducer are connected by spline to transmit power from the electric motor to the reducer. The long half shaft 15 and a half shaft gear 41 provided on the differential are also connected by spline to output power.

[0004] The electric motor of the electric axle drive system is filled with air, and the reducer is filled with gear oil. In order to prevent the gear oil in the reducer from entering the electric motor, three sealing structures are provided between the electric motor and the reducer. The first sealing structure is an oil seal 31 provided between the electric motor housing 10 and the electric motor shaft 14, the second sealing structure is an oil seal 32 provided between the electric motor shaft 14 and the half shaft gear 41, and the third sealing structure is an oil seal 33 provided between the half shaft gear 41 and the long half shaft 15. Therefore, the gear oil in the reducer cannot enter a region A between the hollow electric motor shaft 14 and the long half shaft 15, nor can it enter a spline connection region B between the long half shaft 15 and the half shaft gear 41.

[0005] Because the gear oil in the reducer cannot enter the region A between the electric motor shaft 14 and the long half shaft 15, the electric motor is only cooled by the water cooling jacket 13 and air, which has a very limited cooling effect, which limits the use performance of the electric motor and the requirement for improving the heat resistance of elements. Figure 1 Therefore, the electric motor is only cooled by the water cooling jacket 13 and air, which has a very limited cooling effect, which limits the use performance of the electric motor and the requirement for improving the heat resistance of elements.

[0006] In addition, because the machine oil in the reduction gearbox cannot enter the spline connection area B between the long half shaft 15 and the half shaft gear 41, a layer of lubricating oil is applied to the spline in advance for lubrication. However, the spline connection area B is very close to the motor, and after the motor operates for a period of time, the high temperature emitted by the motor causes the lubricating oil on the spline to evaporate, and dry friction is formed at the spline connection, which easily causes rust and wear on the spline, further causing noise and customer complaints.

[0007] Furthermore, because the oil seal 32 of the second sealing structure is arranged between the motor shaft 14 and the half shaft gear 41, the motor shaft 14 is a cantilever structure with low rigidity, and the half shaft gear 41 is also a floating design, which easily causes the oil seal 32 to leak. Arranging more oil seals increases the risk of oil leakage, and increases the number of elements and the number of corresponding matching surfaces and profile finishing processes, which certainly increases the cost. SUMMARY

[0008] An aspect of the present application aims to provide a cooling and lubricating structure of an electric axle drive system, which arranges an oil seal between the motor shaft away from the reduction gearbox and the long half shaft, so that the machine oil on the side of the reduction gearbox is introduced into the area between the hollow motor shaft and the long half shaft and the spline connection area, the machine oil effectively absorbs the heat generated by the motor, cools the motor shaft and improves the cooling performance of the motor, and lubricates the spline connection area to improve the wear resistance and service life of the spline connection area.

[0009] The purposes and advantages of other aspects of the present application can be further understood from the technical features disclosed in the present application.

[0010] An aspect of the present application proposes the following technical solutions:

[0011] A cooling and lubricating structure of an electric axle drive system is arranged in an electric axle drive system having a motor, a reduction gearbox and a differential, the motor includes a hollow motor shaft, a long half shaft passes through the motor shaft, the reduction gearbox is provided with machine oil, the differential is provided with a half shaft gear, the long half shaft and the half shaft gear are spline linked, an oil seal is arranged between the motor shaft away from the reduction gearbox and the long half shaft, the machine oil in the reduction gearbox enters the area between the motor shaft and the long half shaft to cool the motor shaft, and enters the spline connection area connecting the long half shaft and the half shaft gear to lubricate the spline connection.

[0012] Optionally, according to an embodiment of an aspect of the present application, the oil seal has a static sealing surface sealing with the outer circumference of the motor shaft

[0013] Optionally, according to an embodiment of one aspect of the present application, the oil seal further has a static sealing surface sealed with the outer circumference of the long half shaft.

[0014] Optionally, according to an embodiment of one aspect of the present application, the inner wall of the hollow motor shaft is provided with a forward helical groove extending helically along the motor shaft in the axial direction.

[0015] Optionally, according to an embodiment of one aspect of the present application, the outer wall of the long half shaft is provided with a reverse helical groove extending helically along the long half shaft in the axial direction, and the forward helical groove and the reverse helical groove jointly form an oil circulation loop in the area between the motor shaft and the long half shaft.

[0016] Optionally, according to an embodiment of one aspect of the present application, the oil circulation loop is configured such that when the motor is running, the oil is driven by the rotation of the motor shaft and the long half shaft to enter the area between the motor shaft and the long half shaft from the side of the reduction gearbox, and flow in the forward helical groove and the reverse helical groove towards the oil seal, and then flow back in the forward helical groove and the reverse helical groove from the oil seal to the side of the reduction gearbox.

[0017] Optionally, according to an embodiment of one aspect of the present application, the motor further comprises a motor housing, and the oil seal is further arranged between the motor housing and the motor shaft.

[0018] Another aspect of the present application provides an electric shaft driving system, which comprises the cooling and lubricating structure of the electric shaft driving system according to any one of the technical solutions described above.

[0019] Still another aspect of the present application provides an automobile, which comprises the electric shaft driving system described above.

[0020] One aspect of the present application provides a cooling and lubricating structure of an electric driving system, which removes the oil seal between the motor shaft and the half shaft gear and the oil seal between the half shaft gear and the long half shaft in the prior art, and sets the oil seal between the motor shaft and the long half shaft away from the side of the reduction gearbox, so that the oil in the reduction gearbox can enter the area between the motor shaft and the long half shaft to cool the motor shaft, and enter the spline connection area connecting the long half shaft and the half shaft gear to lubricate the spline connection.

[0021] Since the spline connection area is filled with oil, the wear resistance and service life of the spline are improved.

[0022] Furthermore, since the positive helical groove axially spirally extending along the motor shaft is arranged on the inner wall of the hollow motor shaft and the negative helical groove axially spirally extending along the long half shaft is arranged on the outer wall of the long half shaft, the oil circulation loop is formed by the positive helical groove and the negative helical groove, and when the driving system is working, the oil can circulate in the loop, and at this time, the motor not only relies on the water cooling jacket and air cooling, but also effectively helps the motor to absorb heat, improves the cooling performance of the engine, and achieves better cooling effect. The positive helical groove and the negative helical groove are easy to process, the positive helical groove is located on the inner wall of the motor shaft, and the negative helical groove is located on the outer wall of the long half shaft, so that no additional design space is occupied.

[0023] In addition, the number of oil seals used in the cooling and lubricating structure of the electric shaft driving system is reduced, thereby reducing the risk of oil leakage and increasing the sealing reliability. Reducing the number of oil seals used also reduces the number of parts, so that the number of machined surfaces of the corresponding abutting surfaces is also reduced, thereby reducing the cost.

[0024] The static sealing surface of the second oil seal of the present application is located on the outer circumference of the motor shaft, which increases the design space of the oil seal. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a sectional view of a known cooling and lubricating structure of an electric shaft driving system.

[0026] Figure 2 It is a sectional view of the cooling and lubricating structure of the electric shaft driving system according to an embodiment of an aspect of the present application, showing the oil seal between the motor and the reduction gearbox, and the area where the oil enters the region between the hollow motor shaft and the long half shaft and the spline connection region.

[0027] Figure 3 It is an enlarged view of Figure 2 part C, showing the position of the oil seal of the cooling and lubricating structure of the electric shaft driving system and the static sealing surface of the oil seal.

[0028] Figure 4 It is a partial enlarged sectional view of the motor shaft with a positive helical groove of the cooling and lubricating structure of the electric shaft driving system according to an embodiment of an aspect of the present application, showing the structure of the positive helical groove of the inner wall of the motor shaft.

[0029] Figure 5 It is a partial enlarged view of the long half shaft with a negative helical groove of the cooling and lubricating structure of the electric shaft driving system according to an embodiment of an aspect of the present application, showing the structure of the negative helical groove of the outer wall of the long half shaft.

[0030] The reference signs in the above drawings are explained as follows:

[0031] Cooling and lubrication structure of electric axle drive system 100, 200

[0032] Motor stator 11, 62 Motor rotor 12, 63

[0033] Water jacket 13, 64 Motor shaft 14, 65

[0034] Long half shaft 15, 66 Oil seal 31, 32, 33

[0035] Half shaft gear 41, 75 Motor 60

[0036] Reduction box 70 Differential 80

[0037] First oil seal 71 Second oil seal 72

[0038] Static sealing surface 73, 74 DETAILED DESCRIPTION

[0039] The following description of the embodiments is presented with reference to the accompanying drawings, in which the specific embodiments of the present application are shown by way of illustration. Directional terms, such as "upper", "lower", "front", "back", "left", "right", "top", "bottom" and the like, are used herein for clarity in referring to the accompanying drawings. It is understood that the directional terms are used in the description of the embodiments and are not intended to limit the application. In addition, the embodiments described in the detailed description section are only a few embodiments of the present application and are not all-inclusive of all embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0040] Referring to Figure 2 Fig. 2 is a cross-sectional view of a cooling and lubrication structure of an electric axle drive system 200 according to the present application, wherein the electric axle drive system is provided with a motor 60, a reduction box 70 and a differential 80. The motor 60 includes a motor housing 61, a motor stator 62, a motor rotor 63, a water jacket 64 and a motor shaft 65. The motor shaft 65 is a hollow shaft, and a long half shaft 66 passes through the hollow motor shaft 65. The cooling and lubrication structure of the electric axle drive system 200 according to the present application is provided with two sealing structures, a first oil seal 71 provided between the motor housing 61 and the motor shaft 65, and a second oil seal 72 provided between the motor shaft 65 and the long half shaft 66 on the side away from the reduction box 70. Referring to Figure 3The second oil seal 72 has a static sealing surface 73 sealing with the outer circumference of the motor shaft 65 and a static sealing surface 74 sealing with the outer circumference of the long half shaft 66, so as to ensure that the engine oil cannot further enter into the motor 60. Since the static sealing surface 73 of the second oil seal 72 is arranged on the outer circumference of the motor shaft 65, the space available for the outer circumference of the motor shaft 65 is large, and the size of the oil seal is no longer limited by space and other factors, so that the second oil seal 72 increases the design space and ensures the sealing effect.

[0041] Since the oil seal 72 is arranged on the side of the motor away from the reduction box, the area D between the motor shaft 65 and the long half shaft 66 is communicated with the oil tank of the reduction box 70, so that the engine oil in the reduction box 70 enters the area D between the hollow motor shaft 65 and the long half shaft 66, and enters the spline connection area E connecting the long half shaft 66 and the half shaft gear 75.

[0042] Please refer to Figure 4 and Figure 5 In the present application, the inner wall of the hollow motor shaft 65 is provided with a forward helical groove 651 extending axially along the motor shaft 65, and the outer wall of the long half shaft 66 is provided with a reverse helical groove 661 extending axially along the long half shaft 66. The forward helical groove 651 and the reverse helical groove 661 can function to transport engine oil from the reduction box, and together form an engine oil flow circuit in the area D between the motor shaft 65 and the long half shaft 66. When the electric shaft driving system is working, the motor shaft 65 and the long half shaft 66 rotate in the same direction to form power, driving the engine oil to flow in the engine oil flow circuit formed by the forward helical groove 651 and the reverse helical groove 661. The flow direction of the engine oil flow circuit is shown by arrow F and arrow G in Figure 2 , that is, the direction of the engine oil flowing in the engine oil flow circuit is from the side of the reduction box 70 to the area D between the motor shaft 65 and the long half shaft 66, then flowing in the forward helical groove 651 and the reverse helical groove 661 to the oil seal 72, and then flowing back to the side of the reduction box 70 from the oil seal 72. Since the engine oil enters the area D between the motor shaft 65 and the long half shaft 66, it can effectively absorb the heat generated by the motor shaft 65 during the operation of the motor 60, and effectively improve the cooling performance of the motor 60. In addition to the water cooling jacket 64 and air cooling, the cooling performance of the motor 60 is further improved.

[0043] In addition, since the spline connection area E between the long half shaft 66 and the half shaft gear 75 is also filled with oil, the dry friction of the spline connection is effectively avoided, and the wear resistance and service life of the spline are greatly improved.

[0044] The present application removes the oil seals between the motor shaft and the half shaft gear and between the half shaft gear and the long half shaft in the known electric drive system, and sets an oil seal between the motor shaft and the long half shaft on the side of the motor away from the reduction box, so that the oil in the reduction box enters the area D between the motor shaft and the long half shaft to cool the motor shaft, and enters the spline connection area E connecting the long half shaft and the half shaft gear.

[0045] Since the spline connection area E is filled with oil, the wear resistance and service life of the spline are improved.

[0046] Furthermore, since the inner wall of the hollow motor shaft is provided with a forward helical groove extending axially along the motor shaft, and the outer wall of the long half shaft is provided with a reverse helical groove extending axially along the long half shaft, together forming an oil circulation loop, when the drive system is working, the oil can circulate in the loop, at this time the motor not only relies on water cooling jacket and air cooling, but also effectively helps the motor to absorb heat, improves the cooling performance of the engine, and achieves better cooling effect. The forward helical groove and the reverse helical groove of the present application are easy to process, the forward helical groove is located on the inner wall of the motor shaft, and the reverse helical groove is located on the outer wall of the long half shaft, which does not need to occupy additional design space.

[0047] The present application only uses two oil seals in the electric shaft drive system, compared with the prior art which uses three oil seals, the number of oil seals is reduced, the risk of oil leakage is reduced, and the sealing reliability is increased. Reducing the number of oil seals also means reducing the number of parts, so that the number of machined surfaces of the corresponding butt joint surface is also reduced, thereby reducing the cost.

[0048] The static sealing surface of the second oil seal of the present application is located on the outer circumference of the motor shaft, which increases the design space of the oil seal.

[0049] The above has introduced the present application in detail, and the principles and implementation modes of the present application have been described by applying specific examples; the above examples are only used to help understand the technical solutions and core ideas of the present application; those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A cooling and lubrication structure for an electric axle drive system, provided in an electric axle drive system comprising an electric motor, a reduction gearbox, and a differential, wherein the electric motor comprises a hollow motor shaft through which a long half-shaft passes, the reduction gearbox is provided with engine oil, and the differential is provided with side gears, wherein the long half-shaft and the side gears are spline-connected, and wherein: An oil seal is arranged between the motor shaft and the long half shaft on the side away from the reduction gearbox, the oil in the reduction gearbox enters the area between the motor shaft and the long half shaft to cool the motor shaft, and enters the spline connection area connecting the long half shaft and the half shaft gear to lubricate the spline connection; the inner wall of the hollow motor shaft is provided with a forward helical groove extending axially along the motor shaft; the outer wall of the long half shaft is provided with a reverse helical groove extending axially along the long half shaft, the forward helical groove and the reverse helical groove jointly form an oil circulation loop in the area between the motor shaft and the long half shaft.

2. A cooling and lubrication arrangement for an electric axle drive system according to claim 1, characterized in that: The oil seal has a static sealing surface sealing with the outer circumference of the motor shaft.

3. A cooling and lubrication arrangement for an electric axle drive system according to claim 2, characterized in that: The oil seal also has a static sealing surface sealing with the outer circumference of the long half shaft.

4. A cooling and lubrication arrangement for an electric axle drive system according to claim 1, characterized in that: The oil circulation loop is configured such that when the motor is running, the oil is driven by the rotation of the motor shaft and the long half shaft to enter the area between the motor shaft and the long half shaft from the side of the reduction gearbox, and flow in the forward helical groove and the reverse helical groove towards the oil seal, and then flow back in the forward helical groove and the reverse helical groove from the oil seal to the side of the reduction gearbox.

5. A cooling and lubrication arrangement for an electric axle drive system according to claim 1, characterized in that: The motor comprises a motor housing, and an oil seal is further arranged between the motor housing and the motor shaft.

6. An electric axle drive system characterized by: The electric axle drive system comprises the cooling and lubricating structure of the electric axle drive system according to any one of claims 1-5.

7. An automobile characterized by comprising: The automobile comprises the electric axle drive system according to claim 6. The automobile comprises the electric axle drive system according to claim 6.

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