Bridge driving system

Abstract

The invention relates to a bridge drive system comprising at least one bridge drive unit comprising: an electric machine having a motor shaft (10); the speed change mechanism is provided with a transmission shaft (20) which is connected with the motor shaft in an anti-rotation manner; a bearing set that rotatably supports the motor shaft at both axial ends of the motor; and a rotatable end cap (40) having a cap body (41) having a disc shape as a whole, and a tapered portion (42) configured at the radial center of the cap body, the radial outer profile of the tapered portion being substantially conical, and the small diameter end portion of the tapered portion being formed at the cap body. The motor shaft and the transmission shaft jointly form an inner cavity which is through in the axial direction and is integrally in a conical shape, the large-diameter end of the inner cavity is formed at the motor shaft, and the small-diameter end of the inner cavity is formed at the transmission shaft. The outer diameter of the large-diameter end of the conical part is smaller than the inner diameter of the small-diameter end of the inner cavity. The conical part is arranged to be coaxial with the inner cavity, and the large-diameter end of the conical part extends into or is adjacent to the small-diameter end of the inner cavity. A bearing (31) of the bearing pack is provided with an oil outlet hole (12), the oil outlet hole forms an inlet (12a) in the inner cavity and forms an outlet (12b) at the outer peripheral surface of the motor shaft and / or the transmission shaft, and the outlet is formed at a position which is adjacent to the bearing (31) and is closer to the small-diameter end of the inner cavity relative to the bearing in the axial direction. The inlet is configured at a position closer to the small-diameter end of the inner cavity in the axial direction than the outlet.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicles. Specifically, the present invention relates to a bridge drive system. Background Art

[0002] The bridge drive system includes a motor and a speed-changing mechanism. The stator and rotor of the motor are cooled by means of active oil, and the bearings of the motor are correspondingly lubricated by the active oil in the motor cavity. Herein, the oil flow is first stored in the oil tank at the bottom; then, after being absorbed by the oil pump, the oil flow can flow to the heat exchanger; the cooled oil flow then enters the motor cavity for oil cooling of the stator / rotor and oil lubrication of the bearings. Specifically, the current bearing lubrication is usually achieved in the following ways: on the one hand, the end windings of the motor stator are sprayed with cooling oil, and the cooling oil drops to the bearings of the motor due to gravity, thereby achieving bearing lubrication; on the other hand, the motor rotor can also adopt the method of oil throwing cooling, and in this part, some oil is also thrown to the motor bearings, thereby achieving bearing lubrication; on the other hand, the speed-changing mechanism is passively lubricated by gear oil agitation, so the bearings of the speed-changing mechanism are also lubricated at the same time. Such lubrication schemes are recorded in, for example, patent documents CN208057908U and CN211151749U.

[0003] In a low-temperature environment, the temperatures of the motor stator and rotor are relatively low, and no additional oil cooling is required. In addition, in a low-temperature environment, the viscosity of the oil is relatively high, so the oil pump needs a relatively high pressure to push the oil forward, and for this reason, the sealing surface needs to withstand a relatively high pressure. Therefore, on the one hand, considering the necessity of additional cooling at low temperatures, and on the other hand, considering the oil pump pressure and the risk of sealing surface leakage, it is beneficial to turn off the oil pump under low-temperature working conditions. However, when the oil pump is turned off, the active oil in the motor cavity stops working, and at this time, the bearings in the motor cavity cannot be lubricated by the active oil. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a bridge drive system that can achieve passive lubrication of the motor bearings, especially when the oil pump is turned off in a low-temperature state, the motor bearings can still be lubricated.

[0005] According to the present invention, the above object is achieved by a bridge drive system. The bridge drive system includes at least one bridge drive unit. The bridge drive unit includes: a motor having a motor shaft; a speed change mechanism having a transmission shaft anti-rotationally connected to the motor shaft; a bearing group rotatably supporting the motor shaft at both axial ends of the motor; a rotatable end cover, wherein the end cover has a cover body integrally in a disc shape and a tapered portion formed at the radial center of the cover body, the outer radial contour of the tapered portion is substantially conical, and the small-diameter end of the tapered portion is formed at the cover body. Here, the motor shaft and the transmission shaft together form an axially penetrating and overall conical inner cavity, wherein the large-diameter end of the inner cavity is formed at the motor shaft, and the small-diameter end of the inner cavity is formed at the transmission shaft; the outer diameter of the large-diameter end of the tapered portion is smaller than the inner diameter of the small-diameter end of the inner cavity, and the tapered portion is arranged coaxially with the inner cavity and extends into or adjacent to the small-diameter end of the inner cavity with the large-diameter end; the bearings of the bearing group are provided with oil outlet holes, wherein the oil outlet holes form an inlet in the inner cavity and an outlet on the outer peripheral surface of the motor shaft and / or the transmission shaft, and the outlet is formed at a position adjacent to the bearing and axially closer to the small-diameter end of the inner cavity relative to the bearing, and the inlet is formed at a position axially closer to the small-diameter end of the inner cavity relative to the outlet.

[0006] In some preferred embodiments, the end cover is arranged at the rotating member in the speed change mechanism.

[0007] In some preferred embodiments, a first oil storage groove is formed on the outer peripheral surface of the small-diameter end of the tapered portion.

[0008] In some preferred embodiments, the inside of the tapered portion is configured in a hollow form.

[0009] In some preferred embodiments, a ring-shaped guiding portion is formed at the axial end of the transmission shaft on the small-diameter end side of the inner cavity, and the inner radial contour of the guiding portion and the outer radial contour of the tapered portion match each other and jointly form a guiding channel.

[0010] In some preferred embodiments, the transmission shaft is provided with a second oil storage groove, and the second oil storage groove is located at the port of the guiding channel away from the cover body.

[0011] In some preferred embodiments, the oil outlet holes are formed in the motor shaft.

[0012] In some preferred embodiments, the motor shaft forms an axially penetrating first inner cavity, the transmission shaft forms an axially penetrating second inner cavity, and the first inner cavity and the second inner cavity together form the inner cavity.

[0013] In some advantageous embodiments, the motor shaft is supported by at least two bearings, and at least one oil outlet hole is respectively provided for at least two bearings.

[0014] In some alternative and advantageous embodiments, the bridge drive system includes two bridge drive units arranged such that the motors of the two bridge drive units are adjacent to each other.

[0015] Wherein, in each bridge drive unit, an oil hole is provided only for the bearing in the bearing group that supports the motor shaft at the axial end of the motor close to the speed change mechanism.

[0016] In the bridge drive system according to the embodiment of the present invention, a lubricating oil splashed by the gears in the speed change mechanism is collected by an end cover constructed with a tapered portion, and the lubricating oil is thrown into the small-diameter end of the conical inner cavity formed jointly by the motor shaft and the transmission shaft by the centrifugal force during high-speed rotation. The lubricating oil at the small-diameter end of the inner cavity further advances towards the large-diameter end of the inner cavity under the action of the centrifugal force. When reaching the entrance of the oil hole, part of the lubricating oil reaches the outlet along the oil hole by the centrifugal force and splashes to the bearing by inertia, thereby lubricating the bearing. The bearing passive lubrication solution provided here can achieve the lubrication of the motor bearing when the active oil supply is suspended in the motor cavity, avoiding the risk of bearing failure caused by insufficient bearing lubrication. This allows the oil pump to be turned off at low temperatures, thereby improving the motor efficiency. In addition, since there is no need to pump the high-viscosity oil at low temperatures, an oil pump with a smaller pressure can be selected, saving the cost of the oil pump. At the same time, the leakage risk of the sealing surface is also reduced, and the design difficulty of the sealing surface is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The features, advantages and technical effects of the exemplary embodiments of the present invention will be described below with reference to the drawings.

[0018] Figure 1 is a partial cross-sectional view of the bridge drive system according to the first embodiment;

[0019] Figure 2 is according to Figure 1 a perspective view of the motor shaft in the bridge drive system shown;

[0020] Figure 3 is according to Figure 1 a perspective cross-sectional view of the motor shaft in the bridge drive system shown;

[0021] Figure 4 is according to Figure 1 a perspective view of the transmission shaft in the bridge drive system shown;

[0022] Figure 5 is according to Figure 1 a perspective cross-sectional view of the transmission shaft in the bridge drive system shown;

[0023] Figure 6 is according to Figure 1 a perspective view of the end cover in the bridge drive system shown;

[0024] Figure 7 is a perspective sectional view of an end cover in the bridge drive system shown in Figure 1 ; and

[0025] Figure 8 is a partial view of a sectional view of a bridge drive system according to a second embodiment. Detailed Description of the Invention

[0026] The bridge drive system provided according to the present invention is particularly suitable for pure electric vehicles and hybrid vehicles. The bridge drive system can be used as a power unit to drive the vehicle in pure electric vehicles and hybrid vehicles. In this document, only the operation of the bridge drive system as a power unit is taken as an example for illustration, but it does not limit the bridge drive system to have other functions. For example, in some embodiments, the bridge drive system can also integrate an energy recovery function.

[0027] Figure 1 shows a partial view of a sectional view of a bridge drive system according to a first embodiment. The bridge drive system according to the first embodiment includes a bridge drive unit. The bridge drive unit mainly includes a motor and a speed change mechanism. The speed change mechanism is used to change the torque and speed output by the motor, especially for reducing speed and increasing torque. Here, as Figure 1 shown, the motor and the speed change mechanism are arranged adjacent to each other.

[0028] As Figure 1 shown, the motor has a motor shaft 10. The bridge drive unit further includes a bearing group. The bearing group, more precisely, the bearings 31, 32 in the bearing group, rotatably support the motor shaft 10 at both axial ends of the motor. The type of bearing is not limited herein. Optionally, the bearing can be a single-row bearing, a double-row bearing, a four-row bearing, etc. Optionally, on one axial side of the motor, the motor shaft 10 can be rotatably supported by one or at least two bearings. With the passive lubrication scheme to be detailed in this embodiment and subsequent embodiments, the bearings of the bearing group can be sufficiently lubricated.

[0029] The speed change mechanism has a transmission shaft 20 that is anti-rotationally connected to the motor shaft 10. The transmission shaft 20 is especially used to introduce the torque output by the motor into the input shaft of the speed change mechanism. In this embodiment, the speed change mechanism is configured as a planetary gear transmission mechanism and the input end of the speed change mechanism is a sun gear. Here, the transmission shaft 20 is the sun gear shaft. For this reason, the transmission shaft 20 is integrally formed with a sun gear 35 (see Figure 4 and Figure 5 ).

[0030] Figure 2 and Figure 3 respectively show a perspective view and a perspective sectional view of the motor shaft in the bridge drive system shown in Figure 1 ​Figure 4 and Figure 5 respectively show a perspective view and a perspective sectional view of a drive shaft in the bridge drive system shown in Figure 1 .

[0031] Combined with Figure 1 、 Figure 2 and Figure 3 it can be seen that the motor shaft 10 is configured with a connecting portion 14 for anti-rotationally connecting with the drive shaft 20. Combined with Figure 1 、 Figure 4 and Figure 5 it can be seen that the transmission shaft 20 is configured with a connecting portion for anti-rotationally connecting with the motor shaft 10. The motor shaft 10 and the drive shaft 20 are anti-rotationally connected by means of their respective connecting portions. It should be noted that within the scope of this article, the term "anti-rotationally connected" means: a connection that enables two components not to rotate relative to each other and thus can transmit torque. For example, a fixed connection can also achieve anti-rotationally connected, such as in this embodiment, the motor shaft 10 and the drive shaft 20 are connected by a tight fit through their respective connecting portions. Another example, a spline connection can achieve anti-rotationally connected, herein, on the premise that a passive lubrication scheme according to the inventive concept can be achieved, a small amount of axial relative movement is allowed between the two components that can be anti-rotationally connected.

[0032] The motor shaft 10 and the drive shaft 20 together form an axially penetrating and overall conical inner cavity. Refer to Figure 1 、 Figure 3 and Figure 5 , the motor shaft 10 is formed with a first inner cavity 11 that penetrates axially; the drive shaft 20 is formed with a second inner cavity 22 that penetrates axially. Through the connection of the motor shaft 10 and the drive shaft 20, the first inner cavity 11 and the second inner cavity 22 together form an overall conical inner cavity. Herein, the first inner cavity 11 and the second inner cavity 22 can have the same or different tapers, as long as the opening diameter of the second inner cavity 22 on the motor side is equal to or less than the opening diameter of the first inner cavity 11 on the speed change mechanism side. Herein, the large diameter end of the jointly formed inner cavity is formed at the motor shaft 10, and the small diameter end of the jointly formed inner cavity is formed at the drive shaft 20.

[0033] The bridge drive system further includes a rotatable end cap 40. In this embodiment, refer to Figure 1 , the end cap 40 is arranged at the rotating member in the speed change mechanism and can rotate together with the rotating member when the speed change mechanism is operating. Figure 6 and Figure 7 respectively show a perspective view and a perspective sectional view of a drive shaft in the bridge drive system shown in Figure 1 ​​​​​Stereogram and stereoscopic sectional view of the end cover in the shown bridge drive system. The end cover 40 includes a cover body 41 that is generally disc-shaped as a whole and a tapered portion 42 constructed at the radial center of the cover body 41. The radially outer contour of the tapered portion 42 is substantially conical, and the small-diameter end of the tapered portion 42 is formed at the cover body 41. In this embodiment, the interior of the tapered portion 42 is constructed in a hollow form.

[0034] See Figure 1 , the outer diameter of the large-diameter end of the tapered portion 42 is smaller than the inner diameter of the small-diameter end of the inner cavity, and the tapered portion 42 is arranged coaxially with the inner cavity and extends into or adjacent to the small-diameter end of the inner cavity with its large-diameter end. When the gears in the speed change mechanism agitate the oil, the oil is thrown into the air and drips under the action of gravity. Here, the end cover constructed with the tapered portion is used to collect the falling oil and rely on the centrifugal force during high-speed rotation to throw the lubricating oil into the conical inner cavity formed jointly by the motor shaft 10 and the transmission shaft 20. Here, it can be understood that the arrangement of the tapered portion 42 with its large-diameter end adjacent to the small-diameter end of the inner cavity is premised on being able to throw the lubricating oil into the conical inner cavity when the end cover rotates.

[0035] In this embodiment, preferably, see Figure 1 , Figure 5 and Figure 7 , the transmission shaft 20 is constructed with an annular guiding portion 23 at the axial end on the small-diameter end side of the inner cavity. The radially inner contour of the guiding portion 23 and the radially outer contour of the tapered portion 42 match each other and jointly form an overall annular guiding channel. With the aid of the guiding channel, the lubricating oil can enter or be thrown into the conical inner cavity more precisely. Here, the flow path of the lubricating oil can refer to the arrow shown by Figure 1 . In addition, referring to Figure 7 , a first oil storage groove 43 is constructed at the outer peripheral surface of the small-diameter end of the tapered portion 42. Referring to Figure 5 , the transmission shaft 20 is constructed with a second oil storage groove 24, where the second oil storage groove 24 is located at the port of the guiding channel away from the cover body 41. With the aid of the first oil storage groove 43 and the second oil storage groove 24, more lubricating oil splashed / fallen due to agitation can be collected and stored.

[0036] Combined with Figure 1 , Figure 2 and Figure 3It can be seen that the bearing 31 and the bearing 32 of the bearing group are respectively provided with an oil outlet hole 12 and an oil outlet hole 13. In this embodiment, the oil outlet hole 12 forms an inlet 12a in the inner cavity and forms an outlet 12b on the outer peripheral surface of the motor shaft 10. The outlet 12b is constructed at a position adjacent to the bearing 31 and axially closer to the small-diameter end of the inner cavity relative to the bearing 31, and the inlet 12a is constructed at a position axially closer to the small-diameter end of the inner cavity relative to the outlet 12b. In other embodiments, it is also possible that the oil outlet hole 12 is provided at the transmission shaft 20, or the oil outlet hole 12 is jointly formed by the motor shaft 10 and the transmission shaft 20. In this embodiment, the oil outlet hole 13 forms an inlet 13a in the inner cavity and forms an outlet 13b on the outer peripheral surface of the motor shaft 10. The outlet 13b is constructed at a position adjacent to the bearing 32 and axially closer to the small-diameter end of the inner cavity relative to the bearing 32, and the inlet 13a is constructed at a position axially closer to the small-diameter end of the inner cavity relative to the outlet 13b. With the overall conical inner cavity jointly formed by the motor shaft 10 and the transmission shaft 20, the lubricating oil at the small-diameter end of the inner cavity advances towards the large-diameter end of the inner cavity under the action of centrifugal force. When reaching the inlets 12a, 13a of the oil outlet holes 12, 13, part of the lubricating oil relies on centrifugal force to flow along the oil outlet holes 12, 13 to the outlets 12b, 13b, and thus splashes onto the bearings 31, 32 by inertia and lubricates the bearings 31, 32. Here, the flow path of the lubricating oil can be referred to the arrow shown by Figure 1 In addition, in this embodiment, in order to lubricate the bearings evenly, at least two oil outlet holes 12 distributed in the circumferential direction are provided for the bearing 31, here four oil outlet holes 12, and the oil outlet holes 12 are evenly distributed in the circumferential direction at the same axial position; and at least two oil outlet holes 13 distributed in the circumferential direction are provided for the bearing 32, here four oil outlet holes 12, and the oil outlet holes 13 are evenly distributed in the circumferential direction at the same axial position.

[0037] Figure 8 FIG. shows a partial cross-sectional view of a bridge drive system according to a second embodiment. In this embodiment, the bridge drive system includes a first bridge drive unit and a second bridge drive unit.

[0038] The first bridge drive unit includes: a first motor having a first motor shaft 110, a first speed change mechanism having a first transmission shaft 120, a first bearing group that rotatably supports the first motor shaft 110 at both axial ends of the first motor, and a first end cover 140. The first bearing group here includes a first bearing 131 that supports the first motor shaft 110 at the axial end close to the first speed change mechanism and a second bearing 132 that supports the first motor shaft 110 at the axial end far from the first speed change mechanism.

[0039] The second bridge drive unit includes: a second motor having a second motor shaft 210, a second speed change mechanism having a second transmission shaft 220, a second bearing group rotatably supporting the second motor shaft 210 at both axial ends of the second motor, and a second end cover 240. The second bearing group includes a first bearing 231 supporting the second motor shaft 210 at an axial end close to the second speed change mechanism and a second bearing 232 supporting the second motor shaft 210 at an axial end far from the second speed change mechanism.

[0040] As Figure 8 shown, in this embodiment, the first motor and the second motor are adjacent to each other and are preferably arranged coaxially. The first motor shaft 110 and the first transmission shaft 120 are anti-rotationally connected and jointly form a conical inner cavity. The second motor shaft 210 and the second transmission shaft 220 are anti-rotationally connected and jointly form a conical inner cavity. In this case, the large-diameter ends of the inner cavities of the first bridge drive unit and the second bridge drive unit are arranged adjacent to each other.

[0041] In this embodiment, in the first bridge drive unit, an oil outlet hole 112 is provided only for the first bearing 131 in the first bearing group; in the second bridge drive unit, an oil outlet hole 212 is provided only for the first bearing 231 in the second bearing group.

[0042] In this embodiment, in each bridge drive system, the lubricating oil splashed due to the agitation of the gears in the speed change mechanism is collected by the end covers 140 and 240 configured with tapered portions, and the lubricating oil is thrown into the small-diameter end of the conical inner cavity jointly formed by the corresponding motor shaft and the transmission shaft by the centrifugal force during high-speed rotation. The lubricating oil at the small-diameter end of the inner cavity advances towards the large-diameter end of the inner cavity under the action of the centrifugal force. When reaching the entrances of the oil outlet holes 112 and 212, a part of the lubricating oil reaches the outlet along the oil outlet holes 112 and 212 by the centrifugal force and splashes onto the first bearings 131 and 231 by inertia to lubricate the first bearings, and another part of the lubricating oil continues to advance along the conical inner cavity towards the large-diameter end and finally is thrown out from the axial end opening of the motor shaft, thereby lubricating the second bearings 232 and 132 in the other bridge drive unit. Here, the flow path of the lubricating oil can be referred to the Figure 8 arrows shown.

[0043] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention. In the description of the present invention, it should be noted that the terms "first", "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0044] List of Reference Numerals

[0045] 10 Motor shaft

[0046] 11 First inner cavity

[0047] 12 Oil outlet hole

[0048] 12a Inlet

[0049] 12b Outlet

[0050] 13 Oil outlet hole

[0051] 13a Inlet

[0052] 13b Outlet

[0053] 14 Connecting part

[0054] 20 Transmission shaft

[0055] 22 Second inner cavity

[0056] 23 Guide part

[0057] 23 Second oil storage tank

[0058] 24 Gear

[0059] 31 Bearing

[0060] 32 Bearing

[0061] 40 End cover

[0062] 41 Cover body

[0063] 42 Tapered part

[0064] 43 First oil storage tank

[0065] 110 First motor shaft

[0066] 112 Oil outlet hole

[0067] 120 First transmission shaft

[0068] 131 First bearing

[0069] 132 Second bearing

[0070] 140 First end cover

[0071] 210 Second motor shaft

[0072] 212 Oil outlet hole

[0073] 220 Second transmission shaft

[0074] 231 First bearing

[0075] 232 Second bearing

[0076] 240 Second end cover

Claims

1. A bridge drive system, which includes at least one bridge drive unit, The bridge drive unit includes: A motor having a motor shaft (10), A speed-changing mechanism having a transmission shaft (20) anti-rotationally connected to the motor shaft (10), A bearing set that rotatably supports the motor shaft (10) at both axial ends of the motor, Characterized in that, The bridge drive unit further includes a rotatable end cover (40), wherein the end cover (40) has a cover body (41) that is generally disc-shaped and a tapered portion (42) constructed at the radial center of the cover body (41), the radial outer contour of the tapered portion (42) is substantially conical, and the small-diameter end of the tapered portion (42) is formed at the cover body (41), Wherein, the motor shaft (10) and the transmission shaft (20) together form an axially penetrating and generally conical inner cavity, wherein the large-diameter end of the inner cavity is formed at the motor shaft (10), and the small-diameter end of the inner cavity is formed at the transmission shaft (20), Wherein, the outer diameter of the large-diameter end of the tapered portion (42) is smaller than the inner diameter of the small-diameter end of the inner cavity, and the tapered portion (42) is arranged coaxially with the inner cavity and extends into or is adjacent to the small-diameter end of the inner cavity with its large-diameter end, Wherein, the bearing (31) of the bearing set is configured with an oil outlet hole (12), wherein the oil outlet hole (12) forms an inlet (12a) in the inner cavity and an outlet (12b) on the outer peripheral surface of the motor shaft (10) and / or the transmission shaft (20), wherein the outlet (12b) is constructed at a position adjacent to the bearing (31) and axially closer to the small-diameter end of the inner cavity relative to the bearing (31), and the inlet (12a) is constructed at a position axially closer to the small-diameter end of the inner cavity relative to the outlet (12b).

2. The bridge drive system according to claim 1, wherein, The end cover (40) is arranged at a rotating member in the speed-changing mechanism.

3. The bridge drive system according to claim 1, wherein, A first oil storage groove (43) is constructed on the outer peripheral surface of the small-diameter end of the tapered portion (42).

4. The bridge drive system according to claim 1, wherein, The interior of the tapered portion (42) is constructed in a hollow form.

5. The bridge drive system according to claim 1, wherein, The transmission shaft (20) is constructed with an annular guiding portion (23) at the axial end on the small-diameter end side of the inner cavity, and the radial inner contour of the guiding portion (23) and the radial outer contour of the tapered portion (42) match each other and together form a guiding channel.

6. The bridge drive system according to claim 1, wherein, The transmission shaft (20) is constructed with a second oil storage groove (24), wherein the second oil storage groove (24) is located at the port of the guiding channel away from the cover body (41).

7. The bridge drive system according to claim 1, wherein The oil outlet hole (12) is constructed at the motor shaft (10).

8. The bridge drive system according to claim 1, wherein, The motor shaft (10) forms an axially penetrating first inner cavity (11), and the transmission shaft (20) forms an axially penetrating second inner cavity (22), and the first inner cavity (11) and the second inner cavity (22) together form the inner cavity.

9. The bridge drive system according to any one of claims 1 to 8, wherein, The motor shaft (10) is supported by at least two bearings (31, 32), wherein at least one of the at least two bearings (31, 32) is respectively configured with at least one of the oil outlet holes (12).

10. The bridge drive system according to any one of claims 1 to 8, wherein, The bridge drive system includes two bridge drive units arranged such that the motors of the two bridge drive units are adjacent to each other. Wherein, in each bridge drive unit, the oil outlet holes (112; 212) are provided only for the bearings (131; 231) in the bearing set that support the motor shafts (110; 210) at the axial ends of the motors close to the speed change mechanism.

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