ELECTRIC DRIVE FOR A VEHICLE

Abstract

An electric drive for a vehicle and a vehicle is having at least one electric machine having a rotor shaft and a planetary transmission for dividing the torque introduced via the rotor shaft to a first output shaft and a second output shaft, wherein for decoupling the rotor shaft at least one switching element is provided relative to the torque transmission between the rotor shaft and an element of the planetary transmission.

Claims

1. An electric drive for a vehicle, comprising: at least one electric machine having a rotor shaft; a first output shaft; a second output shaft; a planetary transmission configured to divide a torque introduced via the rotor shaft to the first output shaft and the second output shaft; and at least one switching element configured to decouple the rotor shaft is provided relative to torque transmission between the rotor shaft and an element of the planetary transmission.

2. The electric drive according to claim 1, further comprising: a pinion shaft which is connected to an element of the planetary transmission, wherein the rotor shaft is couplable fixedly in terms of rotation or decouplable relative to the pinion shaft via the at least one switching element.

3. The electric drive according to claim 2, wherein the pinion shaft, when viewed radially, is mounted, at least in part, inside the rotor shaft.

4. The electric drive according to claim 2, wherein the at least one switching element is a positive switching claw element with a sliding sleeve that is axially displaceable.

5. The electric drive according to claim 4, wherein the sliding sleeve is axially movable such that in a closed state of the sliding sleeve the rotor shaft and the pinion shaft are connected to one another fixedly in terms of rotation.

6. The electric drive according to claim 4, wherein the sliding sleeve, the rotor shaft, and the pinion shaft are arranged coaxially to one another.

7. The electric drive according to one of claim 4, wherein the sliding sleeve, when viewed radially, is arranged inside the at least one electric machine.

8. The electric drive according to one of claim 4, wherein the sliding sleeve, when viewed axially, is arranged between the planetary transmission and the at least one electric machine.

9. The electric drive according to claim 1, wherein the at least one switching element is actuatable via an actuator that is electromechanical, hydraulic, or pneumatic.

10. The electric drive according to claim 9, wherein the actuator is an electromechanical actuator having a spindle drive which is driven via an electric motor and configured to axially move a switching fork coupled to the at least one switching element.

11. The electric drive according to claim 1, wherein the rotor shaft, the planetary transmission, the first output shaft, and the second output shaft are arranged coaxially to one another.

12. The electric drive according to claim 1, wherein an axial plain bearing is arranged on the rotor shaft and configured to support axial forces of a pinion shaft connected to an element of the planetary transmission.

13. The electric drive according to claim 2, wherein the planetary transmission comprises a first planetary gear set and a second planetary gear set coupled to the first planetary gear set.

14. The electric drive according to claim 13, wherein a first element of the first planetary gear set is connectable or connected to the rotor shaft and/or the pinion shaft, a second element of the first planetary gear set is connected to the first output shaft, a third element of the first planetary gear set is connected to a first element of the second planetary gear set, a second element of the second planetary gear set is connected to a housing, and a third element of the second planetary gear set is connected to the second output shaft.

15. A vehicle comprising: at least one electric drive comprising: at least one electric machine having a rotor shaft; a first output shaft; a second output shaft; a planetary transmission configured to divide a torque introduced via the rotor shaft to the first output shaft and the second output shaft; and at least one switching element configured to decouple the rotor shaft is provided relative to a transmission of torque between the rotor shaft and an element of the planetary transmission.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is described in more detail hereinafter with reference to the drawings, in which:

[0018] FIG. 1 is a schematic sectional view of an electric drive for a vehicle;

[0019] FIG. 2 is a schematic sectional view of the electric drive along the cutting line A-A according to FIG. 1;

[0020] FIG. 3 is a schematic sectional view of the electric drive; and

[0021] FIG. 4 is a schematic sectional view of the electric drive.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0022] Different variants of an electric drive according to the invention for a vehicle are shown by way of example in FIGS. 1 to 4.

[0023] Independently of the respective variants, the electric drive comprises an electric machine 1 having a rotor shaft 2 and having a planetary transmission for dividing the torque introduced via the rotor shaft 2 to a first output shaft 3 and a second output shaft 4. In order to decouple the rotor shaft 2 from the planetary transmission or from the output shafts 3, 4, it is provided that a switching element is provided relative to the torque transmission between the rotor shaft 2 and an element of the planetary transmission.

[0024] In this manner, for example in passive operation of the electric machine 1 when this electric machine does not transmit any torque, the rotor shaft 2 and thus the electric machine 1 may be decoupled from the planetary transmission or from the output shafts 3, 4.

[0025] Depending on the switching position, via the switching element the rotor shaft 2 is couplable fixedly in terms of rotation or decouplable relative to a pinion shaft 5 which is connected to an element of the planetary transmission. The pinion shaft 5 and the rotor shaft 2 are arranged coaxially to one another, wherein the pinon shaft 5, when viewed radially, is mounted at least in some portions inside the rotor shaft 2 via needle bearings 6.

[0026] A positive switching claw element with an axially displaceable sliding sleeve 7 is provided as the switching element. The sliding sleeve 7 is axially movable such that in the switched state of the sliding sleeve 7 the rotor shaft 2 and the pinion shaft 5 are connected to one another fixedly in terms of rotation. The sliding sleeve 7 and the rotor shaft 2 and the pinion shaft 5 are arranged coaxially to one another.

[0027] The switching element is actuated via an electromechanical actuator that has a spindle drive 11 driven by an electric motor 10, wherein the spindle drive 11 axially moves a switching fork 12 coupled to the sliding sleeve 7, in order to move the sliding sleeve 7 between the switching positions, “couple” or “connect” and “decouple” or “disconnect”.

[0028] The rotor shaft 2 and the planetary transmission and the output shafts 3, 4 are arranged coaxially to one another. A first planetary gear set 13 and a second planetary gear set 14 coupled to the first planetary gear set 13 are provided as the planetary transmission. By interconnecting the two planetary gear sets 13, 14 the torque applied by the rotor shaft 2 is divided to the two output shafts 3, 4, so that an output differential may be dispensed with.

[0029] To this end, for example, two minus-planetary gear sets 13, 14 which are radially nested in one another may be provided. One or two plus-planetary gear sets may be also provided instead of the minus-planetary gear sets.

[0030] In the variants shown, preferably minus-planetary gear sets are provided as the planetary gear sets 13, 14. In this case, it is provided that as the first element of the first planetary gear set 13, a sun gear 15 is connected to the pinion shaft 5, wherein the sun gear 15 and pinion shaft 5 are designed as a common component, in which a running toothing of the sun gear 15 is provided on the pinion shaft 5. As the second element of the first planetary gear set 13, a planetary gear carrier 16 is connected to the first output shaft 3. As the third element of the first planetary gear set 13, a ring gear 17 is connected to a sun gear 18 as the first element of the second planetary gear set 14, wherein the ring gear 17 and the sun gear 18 are formed by a common component with an internal and external toothing. Moreover, as the second element of the second planetary gear set 14, a planetary gear carrier 19 is connected to a housing 20 of the electric drive. Finally, as the third element of the second planetary gear set 14, a ring gear 21 is connected to the second output shaft 4.

[0031] A first variant is shown in FIGS. 1 and 2, in which a first possible position is provided for arranging the sliding sleeve 7 radially inside the electric machine 1, wherein the sliding sleeve 7 together with the switching fork 12, when viewed axially, are located between a bearing 22 of the first output shaft 3 and bearings 23 of the rotor shaft 2. The sliding sleeve 7 is axially movable via an external toothing in an internal toothing as the sliding toothing 8 of the rotor shaft 2, such that an internal toothing of the sliding sleeve 7 may be brought into engagement with an external toothing as the switching toothing 9 of the pinion shaft 5 in the switched state. In the switched state which is shown in FIG. 1, the axially movable sliding sleeve 7 connects the rotor shaft 2 fixedly in terms of rotation to the pinion shaft 5 mounted in the interior. To this end, the axially movable switching fork 12, which is driven by the electric motor 10 via the spindle drive 11, is located in a groove 24 of the sliding sleeve 7 in order to move this sliding sleeve correspondingly axially. The electric motor 10 is designed in one piece with a plug connector and arranged in the region of the housing lead-through 25 and seals this housing lead-through such that an escape of oil from the housing 20 is prevented.

[0032] The pinion shaft 5 is axially mounted between an axial needle bearing 30 supported on the planetary gear carrier 16 of the first planetary gear set 13, and an axial plain bearing 31 supported on the rotor shaft 2. The advantage of the use of an axial plain bearing 31 between the pinion shaft 5 and the rotor shaft 2 is a cost-saving. This is made possible since a stationary operating state, in which differential speed and axial force are applied at the same time to the axial plain bearing 31, is not present.

[0033] FIG. 2 shows a sectional view along the cutting line A-A according to FIG. 1, it being visible therefrom that a groove 26 is provided on either side in a component 33 of the housing 20 through which the switching fork 12 engages on either side in order to actuate the sliding sleeve 7.

[0034] A second variant of the electric drive is shown in FIG. 3, which differs from the first variant only in that a one-sided bearing arrangement of the rotor shaft 2 is provided, in which the two bearings 23 of the rotor shaft 2 are provided on only one side relative to a connecting portion 27 between a rotor carrier 28 and the rotor shaft 2. As a result, an otherwise required housing lead-through of the switching fork 12 and the grooves 26 required therefor are advantageously not required in the component 33 of the housing 20. Production costs may be saved thereby.

[0035] A third variant of the electric drive is shown in FIG. 4, in which in contrast to the first and second variant the sliding sleeve 7, when viewed axially, is arranged between the planetary gear sets 13, 14, on the one hand, and the electric machine 1, on the other hand.

[0036] In the third variant according to FIG. 4, a rotor bearing arrangement is possible once again on either side relative to the connecting portion 27 between the rotor carrier 28 and the rotor shaft 2, as in the first variant according to FIG. 1, but without the switching fork 12 having to engage through the housing in a complex manner, since the sliding sleeve 7, when viewed axially, is arranged between the planetary gear sets 13, 14 and the electric machine 1.

[0037] A coaxially arranged spacer ring 29 is provided on the pinion shaft 5. This spacer ring permits a particularly simple manufacture of the running toothing of the sun gear 15 of the first planetary gear set 13 on the pinion shaft 5 as a common component. Depending on the design, the spacer ring 29 may also be dispensed with and the sliding sleeve 7 directly arranged on the sliding toothing 8. If, however, the spacer ring 29 is provided, the axial plain bearing 31 is located on the side of the spacer ring 29 facing the rotor shaft 2. A driving toothing 32 is located on the radially internal side of the spacer ring 29 for transmitting the torque between the pinion shaft 5 and the spacer ring 29. The sliding toothing 8 on which the sliding sleeve 7 is axially movable is located on the radially external side of the spacer ring 29. The switching toothing 9 is located on the rotor shaft 2. This means that the toothing on the radially internal side of the sliding sleeve 7 at least in the left-hand region has the function of a sliding toothing 8 and in the right-hand region the function of a switching toothing 9. It is also possible for the sliding toothing 8 and the switching toothing 9 to be exchanged. This has the advantage that when the stationary rotor shaft 2 is decoupled, no frictional losses are produced on the switching fork 12.

[0038] Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.