Description

TECHNICAL FIELD

The present invention relates to an electric powertrain system, which may be used in a vehicle, for example an electric vehicle or a hybrid vehicle. The present invention further relates to a vehicle comprising such an electric powertrain system.

BACKGROUND OF THE INVENTION

An electric powertrain system is the core source of motive power in an electric or hybrid vehicle for example. It generally comprises an electric machine and a gearbox; an electric machine shaft of the electric machine and an input shaft of the gearbox are coupled to each other to transmit torque, and will experience highspeed rotation during operation. Thus, it should be ensured that the electric machine shaft of the electric machine and the input shaft of the gearbox are centred properly with respect to each other, to avoid vibration due to radial eccentricity, as well as the resulting noise and relatively low transmission efficiency. Axial positioning of the electric machine shaft and the input shaft should also be ensured, to further enhance the robustness of the entire electric powertrain system. Furthermore, firm coupling of the electric machine shaft to the input shaft of the gearbox and firm support of the electric machine shaft and the input shaft should also be ensured with a compact structure, to ensure that they operate in an optimal state, and thus ensure high transmission efficiency. However, a solution capable of achieving these technical effects simultaneously has not yet been proposed in the prior art.

The present invention is intended to achieve these technical effects through a simple and compact structure.

SUMMARY OF THE INVENTION To this end, the present invention proposes an electric powertrain system, comprising a housing and, located within the housing: an electric machine assembly comprising an electric machine shaft, the electric machine shaft comprising a first electric machine shaft end and a second electric machine shaft end, a gearbox assembly comprising an input shaft, the input shaft comprising a first input shaft end and a second input shaft end, the first input shaft end being inserted in the second electric machine shaft end and forming a coupling part with the second electric machine shaft end, so that the input shaft and the electric machine shaft rotate together coaxially, a first bearing, providing support at the first electric machine shaft end, a second bearing, providing support at the second input shaft end, a third bearing, supporting the input shaft close to the first input shaft end, wherein the coupling part comprises a spline coupling part and a radial centring part, the coupling part being located axially between the third bearing and an extremity of the first input shaft end.

Thus, the electric powertrain system proposed in the present invention can achieve at least the following technical effects. The coupling part formed by the electric machine shaft of the electric machine assembly and the input shaft of the gearbox assembly comprises a spline coupling part and a radial centring part, and it is thereby possible to ensure that torque is transmitted between the electric machine shaft and the input shaft while also ensuring that the electric machine shaft and the input shaft are centred properly with respect to each other, effectively avoiding vibration and noise due to radial eccentricity between the electric machine shaft and the input shaft, and ensuring effective transmission of torque from the electric machine shaft to the input shaft of the gearbox assembly. At the same time, the use of the first bearing, second bearing and third bearing as defined above helps to achieve effective and firm support for the electric machine shaft and input shaft, and thus for the electric machine assembly and gearbox assembly, in a compact structure. In particular, such a layout of the three bearings, and the positioning of the coupling part relative to them and relative to the electric machine shaft and input shaft, allow very firm support of the electric machine shaft and the input shaft of the gearbox assembly, further reducing vibration and noise, and also allow micro-modification design of the teeth of gears of the gearbox assembly, ensuring that the gears are able to present their optimal state and thereby achieve optimal performance during operation, and further helping to reduce noise.

The electric powertrain system proposed in the present invention may further comprise one or more of the following aspects, which may be employed alone or in combination.

In some embodiments, the radial centring part is disposed axially between the spline coupling part and the third bearing.

In some embodiments, the spline coupling part is disposed axially between the radial centring part and the third bearing.

In some embodiments, the radial centring part and the spline coupling part are disposed axially adjacent to each other. Such a structure allows the corresponding centring part and spline coupling part to be conveniently machined on the electric machine shaft and input shaft, and helps to simplify the fitting of the electric machine shaft and the input shaft to each other, thereby reducing design, manufacturing and assembly costs, and increasing cost effectiveness.

In some embodiments, the radial centring part comprises a radial inner surface of the electric machine shaft, and a radial outer surface of the input shaft which is in a clearance fit with the radial inner surface. Such a radial centring part is able to ensure proper centring, is very easy to machine, and facilitates assembly, further increasing cost effectiveness.

In some embodiments, a retaining ring is provided on the first input shaft end of the input shaft, axially between the coupling part and the extremity of the first input shaft end.

In some embodiments, a circumferential groove for accommodating the retaining ring is provided in the first input shaft end, wherein the retaining ring is elastic, so that in the process of assembly, in particular in the process of inserting the input shaft into the electric machine shaft, while the retaining ring is moving through the coupling part with the input shaft, the retaining ring is radially compressed in the circumferential groove, and after the retaining ring has moved through the coupling part with the input shaft, the retaining ring is able to extend radially to abut an inner wall of the electric machine shaft.

Thus, the retaining ring may be provided in a simple manner with a very compact structure, allowing an improvement in axial positioning of the electric machine shaft relative to the input shaft of the gearbox assembly.

In some embodiments, the first bearing comprises a first bearing inner ring and a first bearing outer ring, and an elastic member capable of applying an axial preload to the first bearing is provided between the first bearing outer ring and the housing. The elastic member makes it possible to ensure the axial positioning of the electric machine shaft relative to the input shaft of the gearbox assembly in a very simple and dynamic manner, thereby ensuring torque transmission efficiency, and helping to make the entire electric powertrain system robust.

In another embodiment, a shaft elastic member is provided axially between the input shaft and the electric machine shaft.

In particular, the shaft elastic member is axially disposed between the input shaft and an extremity of the second electric machine shaft end. This allows easing assembly by centring axially the second electric machine shaft. The input shaft can present a diameter reduction to accommodate the shaft elastic member.

In particular, the shaft elastic member is axially disposed between the extremity of the first input shaft end and the electric machine shaft. This allows easing assembly by centring axially the second electric machine shaft.

The shaft elastic member can be fixed on the input shaft. The shaft elastic member can be fixed on the electric machine shaft. The shaft elastic member can be axially movable compared to the input shaft and to the electric machine shaft.

The shaft elastic member can be a conical spring washer. The shaft elastic member can be a coil spring. The shaft elastic member can be a buffer.

In some embodiments, a stop ring for axially positioning the third bearing is provided on the input shaft. It is thereby possible to further secure the third bearing, and thus further secure the input shaft of the gearbox assembly.

In some embodiments, at least one of the first bearing, the second bearing and the third bearing is a deep groove ball bearing.

In some embodiments, the electric powertrain system comprises an oil cooling system for cooling the electric machine assembly.

In some embodiments, the electric powertrain system comprises a water cooling system for cooling the electric machine assembly.

In some embodiments, a lip-like sealing ring is provided between the electric machine shaft and the housing, to fluidically seal a first part of the housing that accommodates the electric machine assembly relative to a second part of the housing that accommodates the gearbox assembly. Thus, in the case where the electric powertrain system comprises a water cooling system for cooling the electric machine assembly, oil in the gearbox assembly can be effectively prevented from flowing into the electric machine assembly, thus preventing the oil from negatively affecting components with poor oil resistance in the electric machine assembly.

In some embodiments, the gearbox assembly employs a two-stage helical gear parallel- shaft arrangement, and comprises a differential. This enables a more compact overall structure.

The present invention further relates to a vehicle comprising an electric powertrain system as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to explain the technical solution of embodiments of the present disclosure more clearly, the drawings that need to be used in the embodiments are briefly described below. It should be understood that the drawings below show only some embodiments of the present disclosure, so should not be regarded as limiting the scope. Those skilled in the art could obtain other related drawings based on these drawings without inventive effort. Among the drawings,

Fig. 1 shows a sectional drawing of an electric powertrain system according to an embodiment of the present invention.

Fig. la shows a partial enlarged drawing of the coupling part in Fig. 1.

Fig. 2 shows a sectional drawing of an electric powertrain system according to another embodiment of the present invention.

Fig. 3 shows a partial enlarged drawing of a first alternative of the coupling part of Fig. 1.

Fig. 4 shows a partial enlarged drawing of a second alternative of the coupling part of Fig. 1.

List of reference labels:

10 electric powertrain system

100 housing

110 first end cap

120 second end cap

130 separating part

150 first housing

160 second housing

170 first housing body

180 second housing body

200 electric machine assembly

210 electric machine shaft

211 first electric machine shaft end

212 second electric machine shaft end

213 extremity of second electric machine shaft end

300 gearbox assembly

310 input shaft

311 first input shaft end

312 second input shaft end

313 extremity of first input shaft end

314 input gear

315 intermediate first gear

316 intermediate second gear

317 stop ring

318 retaining ring

319 circumferential groove 320 differential

330 intermediate shaft

400 first bearing

410 first bearing inner ring

420 first bearing outer ring

430 bearing block

440 elastic member

500 second bearing

510 second bearing inner ring

520 second bearing outer ring

600 third bearing

610 first axial end

630 third bearing inner ring

640 third bearing outer ring

710 conical spring washer

720 buffer

S spline coupling part

C radial centring part

X rotation axis

DETAILED DESCRIPTION OF THE INVENTION

The electric powertrain system according to embodiments of the present disclosure is described in detail below with reference to the drawings. In order to clarify the objective, technical solution and advantages of the present practical disclosure, the technical solution in embodiments of the present disclosure is described clearly and completely below in conjunction with the drawings in embodiments of the present disclosure. Obviously, the embodiments described are some, not all, of the embodiments of the present disclosure.

Thus, the detailed description below of embodiments of the present disclosure provided in conjunction with the drawings is not intended to limit the scope of the present disclosure for which protection is claimed, and merely indicates selected embodiments of the present disclosure. All other embodiments obtained by those skilled in the art based on the embodiments in the present disclosure without expending inventive effort are included in the scope of protection of the present disclosure.

Unless otherwise defined in the context, the singular form includes the plural form. Throughout this specification, the terms "comprising", "having", etc. are used herein to specify the existence of the mentioned characteristic, number, step, operation, element, component or combination thereof, without ruling out the existence or addition of one or more other characteristics, numbers, steps, operations, elements, components or combinations thereof.

In addition, although terms including ordinal numbers such as "first", "second", etc. may be used to describe various components, these components are not limited by these terms, which are merely used only to differentiate one element from another. For example, without departing from the scope of the present disclosure, a first component may be called a second component and, similarly, a second component may be called a first component.

In the description of the present invention, it must be understood that orientational or positional relationships indicated by the terms "upper", "lower", “left”, “right”, “inner”, “outer”, etc. are based on the orientational or positional relationships shown in the drawings, or are the orientational or positional relationships in which the disclosed product is usually placed when used, or are the orientational or positional relationships commonly understood by those skilled in the art, and are merely intended to facilitate and simplify description of the present disclosure, rather than indicating or implying that the device or element in question must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the present disclosure.

The present invention relates to an electric powertrain system, which for example is used in an electric vehicle or hybrid vehicle, and generally comprises an inverter (not shown), an electric machine assembly and a gearbox assembly. The inverter is connected to the electric machine assembly, and provides the necessary source of electrical energy for the electric machine assembly. The source of electrical energy is converted to mechanical energy inside the electric machine assembly, which transmits the mechanical energy to the gearbox assembly. The gearbox assembly transmits the mechanical energy to vehicle wheels for example, generally via a differential included in the gearbox assembly, to drive the wheels to move.

Specifically, as shown in Figs. 1 - 2, the electric powertrain system 10 proposed in the present invention comprises a housing 100. Inside the housing 100 are accommodated the electric machine assembly 200 and the gearbox assembly 300, as well as a support structure which supports the electric machine assembly 200 and the gearbox assembly 300. More specifically, the interior of the housing 100 may be divided into a first part for accommodating the electric machine assembly 200 and a second part for accommodating the gearbox assembly 300. In some embodiments, as shown in Figs. 1 - 2, the housing 100 may be constructed to comprise a first housing 150 for accommodating the electric machine assembly 200 and a second housing 160 for accommodating the gearbox assembly 300. The first housing 150 and second housing 160 are manufactured separately and can be fitted together. This helps to achieve modular manufacture, and allows more flexible design of the electric machine assembly 200 and the gearbox assembly 300. In other embodiments (not shown), the housing may be constructed to comprise a single main body shared by the electric machine assembly and the gearbox assembly. This can reduce the number of components, simplify the assembly process and make the housing more lightweight, and is conducive to spatial compactness.

The electric machine assembly 200 comprises an electric machine shaft 210, which is rotatable about a rotation axis X and comprises a first electric machine shaft end 211 and a second electric machine shaft end 212 axially opposite each other. The first electric machine shaft end 211 may be supported by a first bearing 400. The first bearing 400 may be positioned in a first bearing block 430 disposed on the housing 100. More specifically, the first bearing block 430 may be disposed in an end cap of the housing 100, and the end cap may be called a first end cap 110. This is conducive to overall compactness. More specifically, as shown in Figs. 1 - 2, the first end cap 110 is an end cap of the first housing 150. In addition, the first housing 150 may further comprise a first housing body 170 fitted to the first end cap 110.

The gearbox assembly 300 comprises an input shaft 310. The input shaft 310 comprises a first input shaft end 311 and a second input shaft end 312 axially opposite each other. The second input shaft end 312 may be supported by a second bearing 500. The second bearing 500 is positioned in a second bearing block disposed on the housing 100. More specifically, the second bearing block may be disposed in another end cap of the housing 100. This other end cap may be called a second end cap 120 and is arranged axially opposite the first end cap 110. This is conducive to overall compactness. More specifically, as shown in Figs. 1 - 2, the second end cap 120 is an end cap of the second housing 160. In addition, the second housing 160 may further comprise a second housing body 180 fitted to the second end cap 120.

As shown in Figs. 1 - 2, in the electric powertrain system 10 proposed according to the present invention, the first input shaft end 311 may be inserted in the second electric machine shaft end 212 and form a coupling part with the second electric machine shaft end 212, so that the input shaft 310 is able to rotate together with the electric machine shaft 210 coaxially, and torque is thereby transmitted from the electric machine shaft 210 to the input shaft 310, such that the input shaft 310 is also able to rotate about the rotation axis X. In addition, a third bearing 600 is also provided. The third bearing 600 supports the input shaft 310 close to the first input shaft end 311. In a more specific embodiment, the housing 100 may comprise a separating part 130 with a hole, which at least partially divides the first part for accommodating the electric machine assembly 200 and the second part for accommodating the gearbox assembly 300. The hole allows the electric machine shaft 210 and the input shaft 310 to pass through. The third bearing 600 may be positioned in a third bearing block disposed on the separating part 130. This is conducive to overall compactness. As shown in Figs. 1 - 2, in the case where the housing 100 is constructed to comprise the first housing 150 and the second housing 160, the separating part 130 may be provided integrally with the second housing body 180 of the second housing 160; alternatively, the separating part 130 may be a separate component attached to the housing 100. In addition, the coupling part may comprise a spline coupling part S and a radial centring part C, and is located axially between the third bearing 600 and an extremity 313 of the first input shaft end 311.

In the specific implementation variant shown in Fig. 1, the radial centring part C is disposed axially between the spline coupling part S and the third bearing 600. In the specific implementation variant shown in Fig. 2, the spline coupling part S is disposed axially between the radial centring part C and the third bearing 600.

Thus, in the electric powertrain system 10 proposed in the present invention, the coupling part formed by the electric machine shaft 210 of the electric machine assembly 200 and the input shaft 310 of the gearbox assembly 300 comprises a radial centring part C, and it is thereby possible to ensure that the electric machine shaft 210 and the input shaft 310 are centred properly with respect to each other, such that they are able to rotate together about the same rotation axis X, effectively avoiding vibration and noise due to radial eccentricity between the electric machine shaft 210 and the input shaft 310, and ensuring effective transmission of torque from the electric machine shaft 210 to the input shaft 310 of the gearbox assembly 300. At the same time, the use of the first bearing 400, second bearing 500 and third bearing 600 as defined above helps to achieve effective and firm support for the electric machine shaft 210 and input shaft 310, and thus for the electric machine assembly 200 and gearbox assembly 300, in a compact structure. In particular, such a layout of the three bearings, and the positioning of the coupling part relative to them and relative to the electric machine shaft 210 and input shaft 310, allow very firm support of the electric machine shaft 210 and the input shaft 310 of the gearbox assembly 300, further reducing vibration and noise. Excellent support precision is provided for the input shaft 310 of the gearbox assembly 300 in particular, thereby allowing micro-modification design of the teeth of gears of the gearbox assembly 300, ensuring that the gears are able to present their optimal state and thereby achieve optimal performance during operation, and further helping to reduce noise.

In some embodiments, as shown in Figs. 1 - 2, the radial centring part C and the spline coupling part S are disposed axially adjacent to each other. Such a structure allows the corresponding radial centring part and spline coupling part to be conveniently machined on the electric machine shaft 210 and input shaft 310, and helps to simplify the fitting of the electric machine shaft 210 and the input shaft 310 to each other, thereby reducing design, manufacturing and assembly costs, and increasing cost effectiveness.

In some embodiments, as shown in Figs. 1 - 2, the radial centring part C comprises a radial inner surface of the electric machine shaft 210, and a radial outer surface of the input shaft 310 which is in a clearance fit with the radial inner surface. Such a radial centring part C is able to ensure proper centring, is very easy to machine, and facilitates assembly, further increasing cost effectiveness. In the specific implementation variant shown in Fig. 1, the radial inner surface of the input shaft 310 which forms the radial centring part C may be formed on an annular protruding part; in the specific implementation variant shown in Fig. 2, the radial inner surface of the electric machine shaft 210 which forms the radial centring part C may be formed on an annular protruding part. Thus, in both of the designs described above, the centring part C is formed of a structure that is easy to machine, reducing design, machining and assembly costs. Of course, such designs of the radial centring part are merely exemplary and not exclusive; all common structures capable of achieving radial centring of the electric machine shaft and input shaft are included in the scope of protection of the present invention.

In addition, the electric powertrain system 10 proposed in the present invention is further provided with a series of axial positioning designs, to ensure that the electric machine shaft 210 of the electric machine assembly 200 and the input shaft 310 of the gearbox assembly 300 can be held in the desired position in the axial direction, thereby optimizing the operating performance thereof.

In some embodiments, a retaining ring 318 may be provided on the first input shaft end 311 of the input shaft 310, axially between the coupling part and the extremity 313 of the first input shaft end 311 (as shown in Fig. la). More specifically, a circumferential groove 319 for accommodating the retaining ring 318 may be provided in the first input shaft end 311, and the retaining ring 318 may be elastic, so that in the process of assembly, specifically in the process of inserting the input shaft 310 into the electric machine shaft 210, while the retaining ring 318 is moving through the coupling part with the input shaft 310, the retaining ring 318 is radially compressed in the circumferential groove 319, so as not to hinder the insertion of the input shaft 310. After the retaining ring 318 has moved through the coupling part with the input shaft 310, the retaining ring 318 is able to extend radially to abut an inner wall of the electric machine shaft 210, for axial positioning of the electric machine shaft 210 and input shaft 310 relative to each other. Thus, the retaining ring 318 may be provided in a simple manner with a very compact structure, allowing an improvement in axial positioning of the electric machine shaft 210 relative to the input shaft 310 of the gearbox assembly 300.

In some embodiments, as shown in Figs. 1 - 2, the first bearing 400 comprises a first bearing inner ring 410 and a first bearing outer ring 420. The first bearing inner ring 410 may form an interference fit with the electric machine shaft 210, and the first bearing outer ring 420 may form a transition fit with the electric machine shaft 210, to allow a very small amount of axial displacement of the first bearing outer ring 420 relative to the electric machine shaft 210. In some embodiments, as shown in Figs. 1 - 3, the first bearing block 430, e.g. a steel bearing block, is disposed at the first bearing outer ring 420. It should be noted that in the absence of the first bearing block 430, relative movement of the first bearing 400 and the housing 100 will cause a bearing block hole provided in the housing to steadily increase in size, thus giving rise to a centring problem. The first bearing block 430 avoids such a problem. More specifically, an elastic member 440 such as a wave spring may be further provided between the second bearing outer ring 420 and the housing 100, e.g. the first end cap 110 of the housing 100. The elastic member can apply an axial preload to the first bearing 400, e.g. apply an axial preload towards the input shaft 310 of the gearbox assembly 300, in order to conveniently and dynamically adjust the axial positioning of the electric machine shaft 210 relative to the input shaft 310, thereby ensuring torque transmission efficiency, and helping to make the entire electric powertrain system 10 robust.

In some embodiments, as shown in Figs. 1 - 2, a stop ring 317 for axially positioning the third bearing 600 may further be provided on the input shaft 310 of the gearbox assembly 300. More specifically, the stop ring 317 may be disposed at an axially inner side of a first axial end 610 of the third bearing 600, i.e. at the side which faces towards the electric machine shaft 210. More specifically, the third bearing 600 may comprise a third bearing inner ring 630 and a third bearing outer ring 640. The third bearing inner ring 630 forms an interference fit with the input shaft 310, the third bearing outer ring 640 forms a slight interference fit or transition fit with the input shaft 310, and the stop ring 317 may be disposed to abut the third bearing inner ring 630. Thus, the stop ring 317 can further secure the third bearing 600 axially, and thus further secure the input shaft 310 of the gearbox assembly 300.

In some embodiments, as shown in Figs. 1 - 2, the second bearing 500 comprises a second bearing inner ring 510 and a second bearing outer ring 520. The second bearing inner ring 510 forms an interference fit with the input shaft 310, and the second bearing outer ring 520 may form a loose fit with the input shaft 310.

It should be noted that when the second bearing 500 and third bearing 600 are arranged as described above, the input shaft 310 may be regarded as axially immovable. This ensures that the input shaft 310 transmits torque to a downstream component such as a differential 320 effectively, and helps to make the entire electric powertrain system 10 stable and robust.

In some specific embodiments, at least one of the first bearing 400, the second bearing 500 and the third bearing 600 is a deep groove ball bearing.

In some embodiments, the electric powertrain system 10 may comprise an oil cooling system (not shown) for cooling the electric machine assembly 200. Oil from the gearbox assembly 300 may be delivered to the electric machine assembly 200 by the following two paths: one is to deliver oil to the electric machine shaft 210 through the input shaft 310; an oil hole is machined in the electric machine shaft 210, the oil hole being able to fling oil onto the stator windings to cool the stator ends and windings. Preferably, the electric machine shaft 210 may in this case be configured to be hollow. This is conducive to light weight overall. Alternatively, oil may be delivered to the housing interior of the electric machine assembly through an oil pipe or housing pipeline, and an oil groove is machined on the stator; in this way, the action of cooling the stator is achieved. In addition, oil may also return to the gearbox assembly 300 from the electric machine assembly 200 through a return flow duct, and is thus recycled. In this case, the liplike sealing ring mentioned above is no longer necessary; more specifically, Figs. 1 - 2 correspond to such a situation. In addition, configuring the electric machine shaft 210 to be hollow is conducive to light weight overall.

In some alternative embodiments, the electric powertrain system 10 may also comprise a water cooling system (not shown) for cooling the electric machine assembly 200. The water cooling system may comprise a waterway for water circulation, and in one particular embodiment, the waterway may be provided integrally with the first end cap 110. More specifically, in particular when the housing 100 is constructed to comprise a single main body shared by the electric machine assembly 200 and the gearbox assembly 300, a lip-like sealing ring (not shown) may be provided between the electric machine shaft 210 and the housing 100, to fluidically seal the first part of the housing 100 that accommodates the electric machine assembly 200 relative to the second part of the housing 100 that accommodates the gearbox assembly 300. The lip-like sealing member is a bidirectional sealing member. When the electric machine assembly 200 and the gearbox assembly 300 are running, positive pressure or negative pressure will arise in the housing 100, and the lip-like sealing member is able to sustain bidirectional pressure. Thus, oil in the gearbox assembly 300 can be effectively prevented from flowing into the electric machine assembly 200, thus preventing the oil from negatively affecting components with poor oil resistance in the electric machine assembly 200. At the same time, the presence of the lip-like sealing ring can also prevent water in the water cooling system from flowing into the gearbox assembly 300 due to accidental leakage.

In some specific embodiments, the gearbox assembly 300 employs a two- stage helical gear parallel-shaft arrangement, which enables a more compact overall structure. In addition, the gearbox assembly 300 may comprise the differential 320 as mentioned above; the differential 320 may for example be coupled to the vehicle wheels and thus transmit torque to the wheels. More specifically, the gearbox assembly 300 may comprise an input gear 314, an intermediate first gear 315 and an intermediate second gear 316. The input gear 314 is fixedly coupled to the input shaft 310, and the input gear 314 is preferably integrally formed with the input shaft 310; this helps to achieve a more compact and more stable component. Alternatively, the input gear 314 may be coupled to the input shaft 310 by splines. The intermediate first gear 315 and intermediate second gear 316 are disposed on an intermediate shaft 330. The intermediate shaft 330 is arranged in parallel with the input shaft 310, and the intermediate shaft 330 may be a hollow shaft. The intermediate first gear 315 is transmission-meshed with the input gear 314, and the intermediate second gear 316 may be fixed to the differential 320. A two-stage helical gear parallel-shaft arrangement between the input shaft 310 and the differential 320 is thereby illustratively achieved.

Figure 3 shows an alternative to the coupling part shown on Figure la. A shaft elastic member is provided axially between the input shaft 310 and the electric machine shaft 210. Here, the shaft elastic member is a conical spring washer 710 axially disposed between the input shaft and an extremity of the second electric machine shaft end 213. The input shaft presents a diameter reduction to accommodate the conical spring washer 710.

Figure 4 shows also an alternative to the coupling part shown on Figure la. The elastic member is a buffer 720 axially disposed between the extremity of the first input shaft end 313 and the electric machine shaft 210.

Demonstrative embodiments of the electric powertrain system proposed in the present invention have been described in detail above with reference to preferred embodiments. However, those skilled in the art will understand that without deviating from the concept of the present invention, various modifications and alterations could be made to the specific embodiments above, and various technical features and structures proposed in the present invention could be combined in various ways, without exceeding the scope of protection of the present invention. The scope of the present disclosure is not defined by the embodiments described above, but is defined by the attached claims and their equivalent scope.