Motor

Abstract

The present invention relates to a motor. The motor comprises a stator, a rotor and a motor shaft which are coaxially arranged; and the rotor is located radially between the stator and the motor shaft and is rotatably arranged relative to the stator. The rotor and the motor shaft can relatively rotate around a common central axis within a predetermined rotation range. The motor further comprises a vibration damping mechanism; the vibration damping mechanism is arranged between the rotor and the motor shaft and comprises a cushioning medium; when the rotor and the motor shaft relatively rotate within the predetermined rotation range, the cushioning medium is compressed so as to attenuate torque vibration; and the rotor and a driven ring can transmit torque by means of the cushioning medium and / or can abut against each other circumferentially at each of two limit positions of the predetermined rotation range so as to transmit torque in the corresponding directions. The motor of the present invention has a vibration damping effect.

Description

Electric machine TECHNICAL FIELD

[0001] The present application relates to the technical field of electric machines. In particular, the present application relates to an electric machine with a damping effect. BACKGROUND

[0002] With the development of new energy technology, the field of application of electric machines is becoming more and more extensive. For example, in new energy vehicles, an electric machine is usually provided as a driving device. The electric machine outputs torque through an electric machine shaft, which is usually connected to an external transmission component through a gear and a spline mechanism. Due to the gap between the coupled splines or teeth, the rotating components can produce impact noise of the splines or teeth during operation. For example, when there is no torque transmission or torque reversal in the transmission path, such impact noise is very significant. It is necessary to meet the requirements of high torque transmission and large damping in a limited space to reduce such impact noise. For the current rigid transmission mechanism, it is difficult to solve this problem. In the existing electric machine, the noise of the splines or teeth is usually eliminated by always keeping the splines or teeth of the pair in a pressed state by increasing the torque. However, this way will correspondingly increase the energy consumption and fuel consumption, and increase the working temperature of the battery, thereby affecting the service life of the battery, the electric machine and the related components of the thermal management system.

[0003] SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to provide an electric machine with improved damping effect.

[0005] The above technical problem is solved by an electric machine according to the present application. The electric machine comprises a stator, a rotor and an electric machine shaft arranged coaxially, the rotor being located radially between the stator and the electric machine shaft and being arranged rotatably relative to the stator. The rotor and the electric machine shaft are relatively rotatable around a common central axis within a predetermined rotation range. The electric machine further comprises a damping mechanism arranged between the rotor and the electric machine shaft and comprising a buffer medium, the rotor and the electric machine shaft compressing the buffer medium when relatively rotating within the predetermined rotation range to thereby dampen torque vibration, the rotor and the driven ring being able to transmit torque through the buffer medium and / or being able to abut each other in the circumferential direction at two limit positions of the predetermined rotation range respectively to thereby transmit torque in the corresponding direction. Since the damping mechanism is arranged between the rotor and the electric machine shaft of the electric machine, the damping and buffering effect of the output torque can be realized inside the electric machine, thereby improving the integration and compactness of the system.

[0006] According to a preferred embodiment of the present application, the motor further comprises a driven ring, one or more guide profiles and one or more pistons, the driven ring is radially located between the motor shaft and the rotor and is fixed relative to the motor shaft, the rotor and the driven ring respectively abut each other in a circumferential direction at two limit positions of a predetermined rotation range to be able to transmit torque in a corresponding direction, each guide profile is fixed relative to one of the rotor and the driven ring and faces the other one of the rotor and the driven ring in a radial direction, the other one of the rotor and the driven ring comprises one or more piston cavities, each piston is movably installed in a corresponding piston cavity and abuts a corresponding guide profile, when the rotor rotates relative to the driven ring, each piston can be pushed by a corresponding guide profile to move along a corresponding piston cavity to compress hydraulic fluid contained in the piston cavity as a damping medium. Due to the damping of the pistons when the rotor and the driven ring rotate relative to each other and the compressibility of the hydraulic fluid, the torque vibration on the motor shaft can be effectively damped and the impact noise of the transmission mechanism during commutation or non-torque transmission state can be reduced.

[0007] According to another preferred embodiment of the present application, the rotor and the driven ring can have a neutral position relative to each other between the two limit positions, each guide profile is recessed in a radial direction away from the other one of the rotor and the driven ring and has a maximum depth position in a circumferential middle portion, at the neutral position, each piston abuts the maximum depth position of a corresponding guide profile, the recessed depth of each guide profile gradually decreases in a circumferential direction from a corresponding maximum depth position towards both circumferential ends, so as to push a corresponding piston to move towards a corresponding piston cavity when the rotor and the driven ring deviate from the neutral position. The rotor and the driven ring can be stably positioned at the neutral position in a non-torque transmission state.

[0008] According to another preferred embodiment of the present application, the motor can further comprise a rotor support fixed to a surface of the rotor facing the driven ring in a radial direction, each guide profile is formed on a surface of the rotor support facing the driven ring in a radial direction or formed on a surface of the driven ring facing the rotor support in a radial direction, the rotor indirectly abuts the driven ring in a circumferential direction via the rotor support at the two limit positions respectively. The rotor support can provide support for the rotor on the one hand and provide guide profiles on the other hand.

[0009] According to another preferred embodiment of the present application, one of the rotor support and the driven ring can comprise one or more recesses recessed in a radial direction away from the other one respectively, the other one of the rotor support and the driven ring can comprise one or more protrusions protruding in a radial direction towards the one respectively, each protrusion is inserted into a corresponding recess in a radial direction and abuts a circumferential end of a corresponding recess at the two limit positions respectively, so as to define the predetermined rotation range. Through the shape cooperation of the recesses and the protrusions, on the one hand, the limitation of the rotation range is achieved, and on the other hand, torque in a corresponding direction can be transmitted at the limit positions.

[0010] According to another preferred embodiment of the present application, each guide profile can be formed in a circumferential middle portion of the corresponding recess, and each piston cavity is formed in a circumferential middle portion of the corresponding protrusion. Thereby, a compact circumferential distribution of the limiting structure and the guide profiles is provided.

[0011] According to another preferred embodiment of the present application, each piston cavity can extend in a radial direction, and each piston is movable in the radial direction along the corresponding piston cavity. Thereby, the movement of the pistons and the machining of the piston cavities are facilitated.

[0012] According to another preferred embodiment of the present application, the electric machine can further comprise one or more elastic members, each abutting between the corresponding piston cavity and the corresponding piston, thereby applying an elastic force to the corresponding piston tending to extend the corresponding piston out of the corresponding piston cavity. The elastic force of the elastic members can on the one hand provide a return force during the movement of the pistons from the compression to the release and form a negative pressure cavity to be filled with oil, and on the other hand, compensate for a certain liquid pressure in case of a lack of hydraulic fluid during the movement of the pistons from the release to the compression.

[0013] According to another preferred embodiment of the present application, each piston can comprise a roller, each roller being rotatably mounted on the corresponding piston about a rotation axis parallel to the central axis, such that each piston rolls in rolling contact with the corresponding guide profile via the corresponding roller. Thereby, the friction between the pistons and the guide profiles is reduced.

[0014] According to another preferred embodiment of the present application, the driven ring can not extend in the axial direction beyond the stator and / or the rotor. Thereby, the axial dimension of the electric machine is avoided to be increased.

[0015] According to another preferred embodiment of the present application, the electric machine can comprise a plurality of guide profiles and a corresponding plurality of pistons, and the other of the rotor and the driven ring comprises a corresponding plurality of piston cavities, the plurality of guide profiles and the plurality of piston cavities being respectively circumferentially spaced apart. Thereby, a simple arrangement of the guide profiles and the pistons can be achieved.

[0016] According to another preferred embodiment of the present application, the electric machine can further comprise a rotor support and a driven ring respectively located in the radial direction between the electric machine shaft and the rotor, the driven ring being fixed relative to the electric machine shaft, the rotor support being fixed relative to the rotor, and the damping medium being a damping spring abutting in the circumferential direction between the rotor support and the driven ring. The damping spring can dampen the torque vibration by elastic deformation. The damping spring itself can also transmit the torque between the rotor support and the driven ring.

[0017] According to another preferred embodiment of the present application, the rotor support and the driven ring can respectively abut each other in the circumferential direction at two limit positions of the predetermined rotation range to thereby transmit the torque in the corresponding direction. This means that, in the stable torque transmission state, the rotor support and the driven ring can transmit the torque to each other through the portions abutting each other, without the need for the damping spring as the main torque transmission structure, thereby achieving greater torque transmission capacity.

[0018] According to another preferred embodiment of the present application, one of the rotor support and the driven ring can include a protrusion, and the other of the rotor support and the driven ring can include a groove extending in the circumferential direction, the protrusion being inserted into the groove and being able to move in the circumferential direction in the groove as the rotor support and the driven ring relatively rotate within the predetermined rotation range, the protrusion abutting the corresponding end portion of the groove in the circumferential direction at two limit positions of the predetermined rotation range to thereby be able to transmit the torque in the corresponding direction. Thus, the predetermined rotation range is defined by the shape fit of the protrusion and the groove.

[0019] According to another preferred embodiment of the present application, the driven ring and / or the rotor support can not extend in the axial direction beyond the stator and / or the rotor. Thus, the axial dimension of the motor is avoided from being increased. BRIEF DESCRIPTION OF DRAWINGS

[0020] The present application will be further described below with reference to the accompanying drawings. Like reference numerals are used to represent functionally identical elements in the drawings. In which:

[0021] FIG. 1 shows a longitudinal sectional view of a motor according to one exemplary embodiment of the present application;

[0022] FIG. 2 shows a partial transverse sectional view of the motor shown in FIG. 1;

[0023] FIG. 3 shows a longitudinal sectional view of a motor according to another exemplary embodiment of the present application; and

[0024] FIG. 4 shows a schematic view of a damping spring and a stop structure of the motor shown in FIG. 3. DETAILED DESCRIPTION

[0025] The following will describe a specific embodiment of a motor according to the present application with reference to the accompanying drawings. The following detailed description and drawings are provided to illustrate the principles of the present application by way of example, and the present application is not limited to the preferred embodiments described, the scope of protection of the present application being defined by the claims.

[0026] According to an embodiment of the present application, there is provided a motor which is integrated with a damping mechanism to provide a damping effect. The damping mechanism includes various types of damping medium which can be compressed by the rotor and the motor shaft when they relatively rotate within a predetermined rotation range to thereby damp the torque vibration.

[0027] Figures 1 and 2 show an exemplary embodiment of an electric machine according to the present application, in which a hydraulic piston mechanism is employed as a damping mechanism, and the hydraulic fluid in the hydraulic piston mechanism serves as a damping medium.

[0028] Figure 1 shows a longitudinal section through the center axis O of the electric machine. As shown in Figure 1, the electric machine comprises a stator 10, a rotor 20 and an electric machine shaft 30. The stator 10, the rotor 20 and the electric machine shaft 30 are arranged coaxially around a common center axis O and are distributed at a distance from one another in the radial direction. The stator 10 and the rotor 20 are each cylindrical components, and the electric machine shaft 30 is a circular shaft or a cylindrical component. The rotor 20 is located radially between the stator 10 and the electric machine shaft 30, and the radial positions of the stator 10 and the electric machine shaft 30 can be exchanged, i.e. it is possible for the stator 10 to be located radially outside the rotor 20 and for the electric machine shaft 30 to be located radially inside the rotor 20, or it is also possible for the stator 10 to be located radially inside the rotor 20 and for the electric machine shaft 30 to be located radially outside the rotor 20. In the embodiment shown in Figures 1 and 2, the stator 10 is shown schematically as being located radially outside the rotor 20, and the electric machine shaft 30 is shown schematically as being located radially inside the rotor 20. The electric machine can also comprise a housing 40 for encapsulating the stator 10 and the rotor 20. The stator 10 is fixed relative to the housing 40, the rotor 20 can be rotated relative to the stator 10 about the center axis O, and the rotor 20 and the electric machine shaft 30 can also be rotated relative to one another about the center axis O.

[0029] Furthermore, the electric machine comprises a driven ring 60, one or more guide profiles 51 and one or more pistons 70. The driven ring 60, the guide profile 51 and the piston 70 form a damping mechanism which is connected between the rotor 20 and the electric machine shaft 30. In particular, the driven ring 60 is a cylindrical component which is mounted coaxially in the radial direction between the electric machine shaft 30 and the rotor 20 and is fixed relative to the electric machine shaft 30. Since the electric machine shaft 30 is located radially inside the rotor 20 in the present embodiment, the driven ring 60 is located radially inside the rotor 20 and radially outside the electric machine shaft 30. The driven ring 60 can be fixedly attached to the electric machine shaft 30 or formed integrally with the electric machine shaft 30. Depending on the requirements of the arrangement space, the driven ring 60 can be fixed directly to the electric machine shaft 30 or indirectly via an intermediate component, for example a drive plate.

[0030] The rotor 20 and the driven ring 60 are capable of rotating relative to each other about the common central axis O within a predetermined rotation range. The predetermined rotation range of the rotor 20 and the driven ring 60 relative to each other has two limit positions opposite in the circumferential direction, when the rotor 20 and the driven ring 60 are rotated relative to each other to either limit position, the rotor 20 and the driven ring 60 respectively abut each other in the circumferential direction (by corresponding limit structures, for example, opposite surfaces in the circumferential direction, which can be an integral structure of the rotor 20 and / or the driven ring 60, or a structure of other components fixed to the rotor 20 and / or the driven ring 60), so as to be capable of transmitting torque in the corresponding direction. Here, the corresponding direction refers to the direction of torque that tends to keep the rotor 20 and the driven ring 60 in the current limit position.

[0031] Each guide profile 51 is fixed relative to the rotor 20 and faces the driven ring 60 in the radial direction. In other words, the guide profile 51 is a structure on the circumferential surface of the rotor 20 that faces the driven ring 60 in the radial direction. Such a guide profile 51 can be a structural surface formed integrally with the rotor 20, or can also be a structural surface provided by other components fixed to the rotor 20. For example, in the embodiment shown in FIGS. 1 and 2, the motor can include a rotor support 50 for supporting the rotor 20, the rotor support 50 being fixed to the surface of the rotor 20 that faces the driven ring 60 in the radial direction, each guide profile 51 can be formed on the surface of the rotor support 50 that faces the driven ring 60 in the radial direction, and the rotor 20 indirectly abuts the driven ring 60 in the circumferential direction via the rotor support 50 at the two limit positions of the predetermined rotation range, respectively. For example, in the present embodiment, the driven ring 60 is located radially inward of the rotor 20, therefore, the rotor support 50 is fixed to the radially inner side of the rotor 20 and located radially outward of the driven ring 60, and the guide profile 51 is formed on the radially inner surface of the rotor support 50.

[0032] Corresponding to the one or more guide profiles 51, the driven ring 60 is formed with one or more piston cavities 61, each of which extends from a surface of the driven ring 60 (in the present embodiment, a radially outer surface) facing the guide profile 51 in a radial direction towards an interior of the driven ring 60. Each piston 70 is movably mounted in a corresponding one of the piston cavities 61. Hydraulic fluid is contained in each of the piston cavities 61, and a liquid pressure generated by the hydraulic fluid acts on the corresponding piston 70, so that each piston 70 tends to extend out of the corresponding piston cavity 61 to abut against the corresponding guide profile 51. When the rotor 20 rotates relative to the driven ring 60, each piston 70 can be pushed by the corresponding guide profile 51 to move along the corresponding piston cavity 61, so that the hydraulic fluid contained in the piston cavity 61 is compressed. The liquid pressure generated by the hydraulic fluid acts on the guide profile 51 in the form of pressure via the piston 70, so as to damp the relative rotation between the rotor 20 and the driven ring 60. Due to the damping effect and the compressibility of the hydraulic fluid, torque vibration can be effectively damped. Preferably, each of the piston cavities 61 can extend substantially in the radial direction, and correspondingly, each of the pistons 70 can move substantially in the radial direction along the corresponding piston cavity 61. When the electric machine includes a plurality of guide profiles 51 and a corresponding plurality of pistons 70, the driven ring 60 includes a corresponding plurality of piston cavities 61, and these guide profiles 51 and these piston cavities 61 can preferably be respectively distributed in the circumferential direction, in particular, uniformly distributed.

[0033] Within a predetermined rotation range, the rotor 20 and the driven ring 60 can have a neutral position relative to each other, which is located between (different from) two limit positions of the predetermined rotation range. Each guide profile 51 is concave in a radial direction away from the driven ring 60 (in the present embodiment, towards the radially outer side), and the radial concave depth of the guide profile 51 gradually decreases towards the circumferential ends from a point in the circumferential middle, so that the point in the circumferential middle is a maximum depth position of the guide profile 51. Such a guide profile 51 can be, for example, a circular arc, an arch or a triangular surface, etc. When the rotor 20 and the driven ring 60 are located at the neutral position relative to each other, each piston 70 abuts at the maximum depth position of the corresponding guide profile 51, and at this time, the extrusion force exerted by the piston 70 on the guide profile 51 has substantially no circumferential component. When the rotor 20 and the driven ring 60 are relatively rotated to deviate from the neutral position, each guide profile 51 will push the corresponding piston 70 to move towards the corresponding piston cavity 61, so that the hydraulic fluid in the piston cavity 61 is compressed. At the same time, since the contact point between each piston 70 and the corresponding guide profile 51 deviates from the maximum depth position, the extrusion force exerted by the guide profile 51 on the piston 70 which extends obliquely relative to the tangential direction will have a circumferential component, thereby torque can be transmitted between the rotor 20 and the driven ring 60. Due to the friction between the piston 70 and the guide profile 51 and the compressibility of the hydraulic fluid, torque vibration can be damped.

[0034] Preferably, the driven ring 60 can be formed with one or more liquid inlet ports 63 respectively communicating to one or more piston cavities 61, and the motor can further include one or more check valves 90 respectively. Each check valve 90 is mounted to the liquid inlet port 63 in the corresponding piston cavity 61, such that hydraulic fluid can only flow into the piston cavity 61 via the liquid inlet port 63 in one direction. The other end of the liquid inlet port 63 can be open to a hydraulic fluid supply, so that hydraulic fluid can be supplied to the piston cavity 61.

[0035] Limiting structures for defining the predetermined rotation range can also be respectively provided by the rotor holder 50 and the driven ring 60. For example, as shown in FIG. 2, in a preferred embodiment, the rotor holder 50 can include one or more recesses 52 respectively concave along a radial direction away from the driven ring 60 (in this embodiment, towards the radial outer side), and the driven ring 60 can correspondingly include one or more protrusions 62 respectively convex along a radial direction towards the rotor holder 50 (in this embodiment, towards the radial outer side). Each protrusion 62 is radially inserted into the corresponding recess 52 and respectively abuts at the circumferential two ends of the corresponding recess 52 at two limit positions of the predetermined rotation range. This on one hand prevents the rotor 20 and the driven ring 60 from further rotating relative to each other beyond the predetermined rotation range, and on the other hand can transmit torque between the rotor 20 and the driven ring 60 through the abutting recesses 52 and protrusions 62. When there are multiple recesses 52 and corresponding multiple protrusions 62, these recesses 52 and these protrusions 62 can be respectively distributed along the circumference, in particular uniformly distributed. Further preferably, as shown in FIG. 2, each guide profile 51 can be formed at a circumferential middle portion of a corresponding recess 52, and each piston cavity 61 can be formed at a circumferential middle portion of a corresponding protrusion 62.

[0036] In a preferred embodiment, the motor can further include one or more elastic members 80. Each elastic member 80 is in a pre-compressed state and abuts between the corresponding piston cavity 61 and the corresponding piston 70, so as to apply an elastic force to the corresponding piston 70 tending to extend the corresponding piston 70 out of the corresponding piston cavity 61. The elastic member 80 can be, for example, a coil spring or other component having elastic deformation capability. The elastic force provided by the elastic member 80 can on one hand serve as a supplement to the liquid pressure, and on the other hand can replace the liquid pressure when the hydraulic fluid is insufficient.

[0037] As shown in Figs. 1 and 2, in the preferred embodiment, each piston 70 can include a roller 71 mounted at an end of the respective piston 70 facing the respective guide profile 51 and rotatable relative to the piston 70 about an axis of rotation substantially parallel to the central axis O. For example, each roller 71 can be rotatably mounted to the respective piston 70 by a pin. Each piston 70 can be in rolling contact with the respective guide profile 51 via the respective roller 71, thereby reducing friction when the piston 70 moves relative to the guide profile 51.

[0038] In the preferred embodiment, the driven ring 60 can not extend axially beyond the stator 10 and / or the rotor 20. That is, a projection of the driven ring 60 and the pistons 70 mounted therein, perpendicular to the axial direction, substantially falls within the range of a projection of the stator 10 and / or the rotor 20, perpendicular to the axial direction. This means that the damping mechanism does not increase the axial dimension of the original motor structure.

[0039] In the embodiment shown in Figs. 1 to 2, the guide profile 51 and the mounting position of the pistons 70 can be interchanged. That is, the guide profile 51 can also be formed on the driven ring 60, in which case the pistons 70 and the piston cavities 61 are correspondingly provided on the rotor 20 (also including the rotor support 50).

[0040] Figs. 3 to 4 show another exemplary embodiment of a motor according to the present application, in which a spring mechanism is employed as a damping mechanism.

[0041] As shown in Fig. 3, the motor includes a stator 10, a rotor 20 and a motor shaft 30 substantially identical to the embodiments in Figs. 1 and 2, and the specific structures of these components can be referred to the embodiments in Figs. 1 and 2. In addition, the motor in Fig. 3 further includes a rotor support 50 and a driven ring 60. The rotor support 50 and the driven ring 60 are located radially between the motor shaft 30 and the rotor 20, respectively. Both components can be formed as a disc-shaped structure substantially surrounding the central axis O. The driven ring 60 is fixed relative to the motor shaft 30, while the rotor support 50 is fixed relative to the rotor 20. The rotor support 50 can be rotatably supported on the driven ring 60, for example, by a bearing.

[0042] In this embodiment, the damping medium is a damping spring 100 abutting between the rotor support 50 and the driven ring 60 in the circumferential direction. The electric machine can comprise one or more damping springs 100 distributed in the circumferential direction at intervals. The damping spring 100 can be an arc-shaped or straight helical spring. Each damping spring 100 can be mounted in a pair of spring windows or spring recesses aligned substantially in the axial direction, one of which is formed in the rotor support 50 and the other in the driven ring 60. Each spring window or spring recess limits both ends of the corresponding damping spring 100 in the circumferential direction. Therefore, when the rotor support 50 and the driven ring 60 rotate relatively, the damping spring 100 will be compressed. The damping spring 100 can dampen impact and torque vibration by elastic deformation.

[0043] As shown in FIG. 4, preferably, the rotor support 50 and the driven ring 60 can abut each other in the circumferential direction (via the stop structure instead of the damping spring 100) at two limit positions of a predetermined rotation range respectively to transmit torque in the corresponding direction. This can be achieved by mutually matching stop structures on the rotor support 50 and the driven ring 60. For example, one of the rotor support 50 and the driven ring 60 can comprise a protrusion, for example one or more protrusions 64 protruding in the axial direction on the side surface of the driven ring 60 facing the rotor support 50, and correspondingly, the other of the rotor support 50 and the driven ring 60 can comprise a groove extending in the circumferential direction, for example one or more grooves 53 recessed in the axial direction on the side surface of the rotor support 50 facing the driven ring 60. Each protrusion 64 is inserted into the corresponding groove 53. When the rotor support 50 and the driven ring 60 rotate relatively within the predetermined rotation range, each protrusion 64 moves in the circumferential direction in the corresponding groove 53. At the two limit positions of the predetermined rotation range, each protrusion 64 abuts the corresponding end of the corresponding groove 53 in the circumferential direction, thereby defining the rotation range and being able to transmit torque in the corresponding direction. As shown in FIG. 4, the protrusions and grooves can be arranged alternately in the circumferential direction with the damping springs 100. In addition, the positions of the protrusions and grooves can also be exchanged with each other.

[0044] Alternatively, in the embodiment shown in FIG. 3, the stop structure such as the protrusions and grooves can also not be provided to define the rotation range and transmit torque, but only the damping springs 100 are used to define the rotation range and transmit torque. At this time, the predetermined rotation range will be determined by the structure, elasticity and mounting method of the damping springs 100. At the same time, within the predetermined rotation range and at the two limit positions of the predetermined rotation range, torque is transmitted only by the damping springs 100.

[0045] Similar to the embodiments of FIGS. 1 and 2, in the embodiments shown in FIGS. 3 and 4, the driven ring 60 and / or the rotor support 50 also preferably do not extend axially beyond the stator 10 and / or the rotor 20, thereby obtaining a more compact structure.

[0046] In the electric machine according to the present application, a damping mechanism using different damping media is added, whereby the torque vibration output by the electric machine shaft can be reduced, and the gear impact noise when the electric machine torque is reversed can be reduced. In addition, such an electric machine can achieve decoupling of the electric machine shaft and the rotor in a non-torque state, thereby reducing the vibration noise of the gear. Therefore, such an electric machine has good NVH (noise, vibration and harshness) performance.

[0047] Although the possible embodiments are described in the above description by example, it is understood that there are still numerous variations of the embodiments that are possible through all the known and otherwise easily conceivable technical features and implementation forms. Furthermore, it should be understood that the exemplary embodiments are merely examples and that the embodiments are in no way limiting on the protection scope, application and configuration of the present application. The foregoing description is intended more to provide a technical guide for the skilled person to transform at least one exemplary embodiment, wherein various changes can be made without departing from the protection scope of the claims, especially with respect to the function and structure of the components.

[0048] Legend 10 stator 20 rotor 30 electric machine shaft 40 housing 50 rotor support 51 guide profile 52 recess 53 groove 60 driven ring 61 piston cavity 62 protrusion 63 liquid inlet 64 protrusion 70 piston 71 roller 80 elastic member 90 one-way valve 100 damping spring O center axis

Claims

1. An electric machine comprising a stator (10), a rotor (20) and a machine shaft (30) arranged coaxially, the rotor (20) being located radially between the stator (10) and the machine shaft (30) and being arranged rotatably relative to the stator (10), characterized in that the rotor (20) and the machine shaft (30) are relatively rotatable about a common central axis (O) within a predetermined rotation range, the electric machine further comprising a damping mechanism arranged between the rotor (20) and the machine shaft (30) and comprising a damping medium which is compressed by the rotor (20) and the machine shaft (30) upon relative rotation within the predetermined rotation range in order to damp torque vibrations, the rotor (20) and the driven ring (60) being torque-transmissively connectable via the damping medium and / or being circumferentially abuttable against each other at two limit positions of the predetermined rotation range in order to transmit torque in the respective direction.

2. The electric machine of claim 1, wherein, the electric machine further comprising a driven ring (60), one or more guide profiles (51) and one or more pistons (70), the driven ring (60) being located radially between the machine shaft (30) and the rotor (20) and being fixed relative to the machine shaft (30), the rotor (20) and the driven ring (60) being circumferentially abuttable against each other at two limit positions of the predetermined rotation range in order to be able to transmit torque in the respective direction, each guide profile (51) being fixed relative to one of the rotor (20) and the driven ring (60) and facing the other one of the rotor (20) and the driven ring (60) in a radial direction, the other one of the rotor (20) and the driven ring (60) comprising one or more piston cavities (61), each piston (70) being movably mounted in a respective piston cavity (61) and abutting against a respective guide profile (51), each piston (70) being movable along a respective piston cavity (61) by a respective guide profile (51) upon rotation of the rotor (20) relative to the driven ring (60) in order to compress hydraulic fluid accommodated in the piston cavity (61) as the damping medium.

3. The electric machine of claim 2, wherein, the rotor (20) and the driven ring (60) having a neutral position relative to each other between the two limit positions, each guide profile (51) being concave in a radial direction facing away from the other one of the rotor (20) and the driven ring (60) and having a maximum depth position in a circumferential middle portion, at the neutral position each piston (70) abutting at the maximum depth position of a respective guide profile (51), the concave depth of each guide profile (51) gradually decreasing in a circumferential direction from the respective maximum depth position towards the circumferential ends in order to urge a respective piston (70) to move towards inside a respective piston cavity (61) upon deviation of the rotor (20) and the driven ring (60) from the neutral position.

4. The electric machine of claim 3, wherein, The motor further comprises a rotor support (50) fixed to a surface of the rotor (20) facing the driven ring (60) in a radial direction, each guide profile (51) being formed on a surface of the rotor support (50) facing the driven ring (60) in a radial direction or on a surface of the driven ring (60) facing the rotor support (50) in a radial direction, the rotor (20) indirectly abutting the driven ring (60) in a circumferential direction via the rotor support (50) at the two limit positions respectively.

5. The electric machine of claim 4, wherein, One of the rotor support (50) and the driven ring (60) comprises one or more recesses (52) respectively recessed in a radial direction away from the other, the other of the rotor support (50) and the driven ring (60) comprises one or more protrusions (62) respectively protruding in a radial direction towards the one, each protrusion (62) being radially inserted into a corresponding recess (52) and abutting circumferential two ends of the corresponding recess (52) at the two limit positions respectively, thereby defining the predetermined rotation range.

6. The electric machine of claim 5, wherein, Each guide profile (51) is formed in a circumferential middle portion of a corresponding recess (52), each piston cavity (61) is formed in a circumferential middle portion of a corresponding protrusion (62).

7. The electric machine of claim 2, wherein, Each piston cavity (61) extends in a radial direction, each piston (70) is radially movable along a corresponding piston cavity (61).

8. The electric machine of claim 2, wherein, The motor further comprises one or more elastic members (80), each elastic member (80) abutting between a corresponding piston cavity (61) and a corresponding piston (70), thereby applying an elastic force to the corresponding piston (70) tending to extend the corresponding piston (70) out of the corresponding piston cavity (61).

9. The electric machine of claim 2, wherein, Each piston (70) comprises a roller (71), each roller (71) being rotatably mounted on the corresponding piston (70) around a rotation axis parallel to the central axis (O) such that each piston (70) rolls in contact with a corresponding guide profile (51) via the corresponding roller (71).

10. The electric machine of claim 2, wherein, The driven ring (60) does not extend axially beyond the stator (10) and / or the rotor (20).

11. The electric machine of any one of claims 2 to 10, characterized by The motor comprises a plurality of guide profiles (51) and a corresponding plurality of pistons (70), the other of the rotor (20) and the driven ring (60) comprises a corresponding plurality of piston cavities (61), the plurality of guide profiles (51) and the plurality of piston cavities (61) are respectively distributed in a circumferential direction.

12. The electric machine of claim 1, wherein, The motor further comprises a rotor support (50) and a driven ring (60) respectively located in a radial direction between the motor shaft (30) and the rotor (20), the driven ring (60) being fixed relative to the motor shaft (30), the rotor support (50) being fixed relative to the rotor (20), the buffer medium being a shock absorbing spring (100) abutting in a circumferential direction between the rotor support (50) and the driven ring (60).

13. The electric machine of claim 12, wherein, The rotor support (50) and the driven ring (60) abut against each other in the circumferential direction at both limit positions of the predetermined rotation range in order to transmit a torque in the respective direction.

14. The electric machine of claim 13, wherein, One of the rotor support (50) and the driven ring (60) comprises a protrusion (64) and the other of the rotor support (50) and the driven ring (60) comprises a circumferentially extending recess (53), the protrusion (64) being inserted into the recess (53) and being movable in the circumferential direction in the recess (53) with the rotor support (50) and the driven ring (60) being relatively rotated within the predetermined rotation range, at both limit positions of the predetermined rotation range the protrusion (64) abutting against a respective end of the recess (53) in the circumferential direction in order to be able to transmit a torque in the respective direction.

15. The electric machine of any one of claims 12 to 14, wherein, The driven ring (60) and / or the rotor support (50) do not extend axially beyond the stator (10) and / or the rotor (20).

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