Drive train for motor vehicle

Abstract

The invention relates to a drive train (10) for a motor vehicle, the drive train (10) having at least one first electric machine (EM1) designed to provide a first drive torque, a second electric machine (EM2) designed to provide a second drive torque, a first driven axle (20), a second driven axle (22) and a distribution transmission (12). The distribution transmission (12) is designed to transmit the first drive torque and the second drive torque to the two driven axles (20, 22) selectively at a first transmission ratio or at least one second transmission ratio different therefrom. The invention also relates to a motor vehicle having a drive train (10).

Description

Technical Field

[0001] The present invention relates to a drive train for a motor vehicle. The present invention also relates to a motor vehicle. Background Art

[0002] As is well known, for motor vehicles, each axle of the drive train has an electric motor. This allows different drive powers to be provided to the axles. However, if one axle slips, the full drive power can no longer be provided to the other axle. Consequently, the drive power of the remaining motor may no longer be sufficient to move the vehicle as intended. Therefore, a locking mechanism may be provided between the two axles. Nevertheless, each electric motor must be provided with a transmission device, which, for example, has an angle gear and a differential and is designed to provide different transmission ratios. The locking mechanism also constitutes an additional component that requires structural space and must be maintained. This results in an expensive, heavy, and space-consuming drive train. Summary of the Invention

[0003] A first aspect relates to a drive train for a motor vehicle. The drive train may be configured to provide propulsion for the motor vehicle. To this end, the drive train may, for example, include a motor and a driven member. The motor vehicle may, for example, be configured as a passenger car, a work machine, or a special vehicle (e.g., a fire truck).

[0004] The drive train includes at least one first electric motor configured to provide a first drive torque and a second electric motor configured to provide a second drive torque. The electric motor may, for example, include a stator and a rotor. The electric motor may be configured to convert electrical energy into mechanical energy. Additionally, the electric motor may be configured to recover energy. The drive torque may be provided on the motor shaft of each electric motor. The numbering of the drive torques as first drive torque and second drive torque is intended to relate the respective electric motors. The electric motors may, for example, be configured as asynchronous motors or synchronous motors. An inverter may be provided for each electric motor. The drive train may include an electrical energy accumulator (such as a battery) with which electrical energy can be supplied to the electric motors.

[0005] The drive train includes a first driven axle and a second driven axle. The driven axle may be, for example, the front axle or rear axle of a motor vehicle. One or more wheels or other driven devices may be secured to each end of each driven axle. The vehicle may be parked on the ground with its wheels. The drive train may be configured to transmit drive torque to the driven axles to drive the motor vehicle. The driven axles may, for example, include a differential, which may also include a differential lock.

[0006] The drive train includes a splitter transmission. The splitter transmission is configured to selectively transmit a first drive torque and a second drive torque to two driven axles at a first transmission ratio or at least one second, different transmission ratio. To this end, the splitter transmission may, for example, include two different spur gear stages, wherein a shift element selectively transmits the drive torque via the first or second of the two spur gear stages. The splitter transmission may, for example, include a planetary gear set whose transmission ratio from the input shaft to the output shaft can be varied by a shift element. The splitter transmission may also have more than two transmission ratio stages. The splitter transmission may also be configured to continuously vary the transmission ratio. The splitter transmission may also be configured to provide freewheeling. The splitter transmission may be configured to provide different transmission ratio stages during torque transmission. The at least two selectable transmission ratios eliminate the need for a transmission for each electric motor in the drive train, thereby making the drive train compact, lightweight, and cost-effective.

[0007] The distribution transmission can be configured to, for example, add the first drive torque and the second drive torque before the transmission ratio is switched. The distribution transmission can be configured to transmit the drive power of the two electric motors to the respective driven axles. The distribution transmission can, for example, be configured to constantly distribute the drive torque to the two driven axles. The distribution transmission can also be configured to variably distribute the drive torque to the two driven axles. For example, by switching accordingly, it is possible to selectively supply the drive torque only to the first axle or only to the second axle. In another mode, the drive torque is directed to both axles.

[0008] In another embodiment of the drive train, the distribution transmission has a single input shaft with a first end and a second end. A first electric motor can be coupled to the first end, and a second electric motor can be coupled to the second end. This design makes it possible to add the two drive torques of the electric motors in a particularly simple and robust manner and then transmit the drive torque to the corresponding driven axle of the drive train in one of at least two transmission ratios. This design can be particularly suitable when the two electric motors are designed for the same or at least similar speed ranges. For example, each end of the input shaft can have a flange, to which the motor shaft is permanently connected or connected in a switchable manner in a rotationally fixed manner. Each end of the single input shaft can, for example, protrude from the housing of the distribution transmission.

[0009] Alternatively, the distribution gear can also have two input shafts, with one of the two electric motors being coupled to each of the two input shafts. This allows the drive torques of the two electric motors to be fed in with different pre-gear ratios before being added together. This simplifies the integration of different electric motors.

[0010] In another embodiment of the drive train, the motor shaft of the first electric motor is permanently connected to the input shaft of the distribution transmission in a rotationally fixed manner. Alternatively or additionally, the motor shaft of the second electric motor can be permanently connected to the input shaft of the distribution transmission in a rotationally fixed manner. This results in a cost-effective and robust design with fewer switching elements. The motor shaft can, for example, be permanently connected to the rotor of the electric motor in a rotationally fixed manner or form the rotor. "Permanently connected in a rotationally fixed manner" means that in all specified conditions, both rotating elements rotate together at the same angular velocity. The permanent rotationally fixed connection can be formed, for example, by a screw connection or by an integral design.

[0011] Alternatively, the motor shaft of the first electric machine can be connected to the input shaft of the distribution transmission in a rotationally fixed manner. For example, the motor shaft can be connected to the input shaft in a rotationally fixed manner by operating a shift element. For example, if the shift element is designed as a friction clutch, a rotationally fixed connection can also be subject to intentional or unintentional slip. In this context, the connection is still considered to be rotationally fixed. For additional pre-transmission ratios, the motor shaft can also be mechanically connected or capable of being connected to the input shaft of the distribution transmission via one or more spur gear stages. Alternatively or additionally, the motor shaft of the second electric machine can also be connected to the input shaft of the distribution transmission in a rotationally fixed manner.

[0012] In another embodiment of the drive train, the distribution transmission has a first output shaft that can be coupled to a first driven axle. Alternatively or in addition, the distribution transmission can have a second output shaft that can be coupled to a second driven axle. This makes it possible to variably distribute the drive torque to the two driven axles. By means of a couplable connection, for example, one of the two driven axles can be decoupled so that the drive torque is directed only to the axle that is not slipping. A permanent rotationally fixed connection or a mechanical working connection can be provided between each output shaft of the distribution transmission and the driven axle. The output shaft can be connected to one or more driven axles, for example, by means of a cardan shaft. For example, in the case of a selected transmission ratio of the distribution transmission, the two output shafts can have different rotational speeds.

[0013] In another embodiment of the drive train, the two output shafts of the distributor transmission are arranged coaxially with one another. This results in a particularly compact design. Furthermore, if both driven axles are designed identically, compensating for height differences between the output shaft of the distributor transmission and the driven axles may be unnecessary.

[0014] Another embodiment of the drive train provides for the two output shafts of the distribution gear to be arranged with their axes parallel to one another, offset from one another. This makes it unnecessary to compensate for the height difference between the output shaft of the distribution gear and the driven axles, for example, if the two driven axles have different heights. For example, the diameter of the wheels on the rear axle may be larger than the diameter of the wheels on the front axle, leading to a corresponding arrangement. For example, the two output shafts may be arranged offset from one another in the vehicle's height direction. Alternatively, or additionally, the two output shafts may be arranged in the same position in the vehicle's transverse direction, for example, centered.

[0015] In another embodiment of the drive train, the distribution transmission has a single output shaft that can be coupled to a first driven axle and a second driven axle. This results in a particularly simple design. This design is particularly advantageous when both driven axles are generally driven at the same speed. For example, the single output shaft can be permanently connected to both driven axles in a rotationally fixed manner or can be switchably connected in a rotationally fixed manner.

[0016] In another embodiment of the drive train, the two motors are designed for the same speed range. For example, the two motors can be operated within the same speed range and, alternatively or additionally, have the same efficiency within the same speed range. This makes the distribution drive particularly simple, as can the control of the motors. For example, the two motors can be designed identically, allowing many common components to be installed in the drive train.

[0017] Another embodiment of the drive train provides a third driven axle. For example, the third driven axle can be arranged adjacent to the second driven axle. The third driven axle can improve off-road capability and the maximum weight of the vehicle. The distribution transmission can be configured to selectively transmit the first drive torque and the second drive torque to the third driven axle at a first transmission ratio or a second transmission ratio. This eliminates the need for an additional transmission and, alternatively or additionally, eliminates the need for a separate motor for driving the third axle.

[0018] In another embodiment of the drive train, the drive train is configured to transmit drive torque from the distribution transmission to both the second driven axle and the third driven axle. The second axle can, for example, be mechanically operatively connected to the third axle. The second axle can be configured as a through-axle. Drive torque can, for example, be transmitted from the distribution transmission via the second axle to the third axle. This allows for simple integration of the third driven axle into the motor vehicle.

[0019] Alternatively, the third driven axle can be directly connected to the distribution gear so that the drive torque can be transmitted to it while bypassing the other driven axles. For this purpose, a third cardan shaft can be provided, for example. The third axle can then be driven independently of the other axles, thereby enabling more flexible distribution of the drive torque to the axles. For this purpose, the distribution gear can also have, for example, a third output shaft.

[0020] Another embodiment of the drive train includes a fourth driven axle. The distribution transmission can be configured to selectively transmit the first drive torque and the second drive torque to the fourth driven axle at a first transmission ratio or a second transmission ratio. Thus, additional driven axles can be provided. For example, the fourth driven axle can be arranged adjacent to the first driven axle. The fourth driven axle can enhance off-road capability and the maximum weight of the vehicle.

[0021] In another embodiment of the drive train, the drive train is configured to transmit drive torque from the distribution gear to both the first driven axle and the fourth driven axle. The first axle can, for example, be mechanically operatively connected to the fourth axle. The first axle can be configured as a through-axle. Drive torque can, for example, be transmitted from the distribution gear via the first axle to the fourth axle. This allows for simple integration of the fourth driven axle into the motor vehicle.

[0022] Alternatively, the fourth driven axle can be directly connected to the distribution gear so that the drive torque can be transmitted to it while bypassing the other driven axles. For this purpose, a fourth cardan shaft can be provided, for example. The fourth axle can then be driven independently of the other axles, allowing for more flexible distribution of the drive torque to the axles. For this purpose, the distribution gear can also have, for example, a fourth output shaft.

[0023] Another aspect relates to a motor vehicle. The motor vehicle has a drive train according to the first aspect. For various advantages and other features, refer to the description of the first aspect, wherein the design of the first aspect also forms the design of the second aspect, and vice versa. The drive train is configured to provide driving force for the motor vehicle. For example, the motor vehicle can be driven forward or reverse using a first driving torque and, alternatively or additionally, a second driving torque.

[0024] In another embodiment of the motor vehicle, the motor vehicle has an additional motor, which is designed, for example, as an electric motor. This additional motor or electric motor can be designed to drive auxiliary consumers. For example, it can provide torque to a power take-off shaft. This makes the distribution transmission particularly simple and compact. For example, the distribution transmission can be without a power take-off shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A first embodiment of a drive train for a motor vehicle is schematically shown.

[0026] Figure 2 A second embodiment of a drive train for a motor vehicle is schematically shown.

[0027] Figure 3 A third specific embodiment of a drive train for a motor vehicle is shown schematically. DETAILED DESCRIPTION

[0028] Figure 1 A drive train 10 for a motor vehicle is shown, comprising a first electric motor EM1 and a second electric motor EM2 of identical design. The first electric motor EM1 is configured to provide a first drive torque to a first motor shaft. The second electric motor EM2 is configured to provide a second drive torque to a second motor shaft, wherein the second electric motor EM2 has only one motor shaft. The drive train 10 comprises a distribution gear 12. The distribution gear 12 has a single input shaft 14 extending transversely through the housing of the distribution gear 12. The input shaft 14 has a flange on the left side, which, in the embodiment shown, is permanently connected to the first motor shaft in a rotationally fixed manner. The input shaft 14 has a further flange on the right side, which, in the embodiment shown, is permanently connected to the second motor shaft in a rotationally fixed manner. As a result, the two electric motors EM1 and EM2 are coupled to the distribution gear 12, and the first and second drive torques are summed at the input shaft 14.

[0029] The distribution transmission 12 has a first output shaft 16 and a second output shaft 18. The distribution transmission 12 is configured or constructed so that the torque accumulated at the input shaft 14 can be selectively transmitted to the two output shafts 16 and 18 of the distribution transmission 12 at least in a first transmission ratio and a second, different transmission ratio. The distribution of the drive torque between the two output shafts 16 and 18 is variable.

[0030] The first output shaft 16 is mechanically operatively connected to a first driven axle 20 via a first cardan shaft. The second output shaft 18 is mechanically operatively connected to a second driven axle 22 via a second cardan shaft. Each driven axle 20, 22 has wheels fastened to both sides, by which the vehicle rests on the ground and is subjected to the respective drive torque.

[0031] Figure 2A second embodiment of the drive train 10 is shown. This embodiment is essentially identical to the first embodiment, with only the differences being described. In the second embodiment, only a third driven axle 24 is additionally provided. The distribution transmission 12 is configured to selectively transmit the first drive torque and the second drive torque to the third driven axle 24 at a first transmission ratio or a second transmission ratio. To this end, the third driven axle 24 is mechanically operatively connected to the second driven axle 22. The corresponding drive torque is then transmitted from the second output shaft 18 via the second driven axle 22 to the third driven axle 24. The third driven axle 24 is arranged adjacent to the second driven axle 22. The second driven axle 22 is configured to transmit torque to the third driven axle 24.

[0032] Figure 3 A third embodiment of the drive train 10 is shown. This embodiment is essentially identical to the second embodiment; only the differences are described. In the third embodiment, a fourth driven axle 26 is additionally provided. The distribution transmission 12 is configured to selectively transmit the first drive torque and the second drive torque to the fourth driven axle 26 at either the first or second transmission ratio. To this end, the fourth driven axle 26 is mechanically operatively connected to the first driven axle 20. The corresponding drive torque is then transmitted from the first output shaft 16 via the first driven axle 20 to the fourth driven axle 26. The fourth driven axle 26 is arranged adjacent to the first driven axle 20. The first driven axle 20 is configured to transmit torque to the fourth driven axle 26.

[0033] Reference Signs List

[0034] 10 Drivetrain

[0035] 12 distribution transmission device

[0036] 14 Input shaft

[0037] 16First output shaft

[0038] 18 Second output shaft

[0039] 20 First driven axle

[0040] 22 Second driven axle

[0041] 24Third driven axle

[0042] 26 Fourth driven axle

[0043] EM1 first motor

[0044] EM2 second motor

Claims

1. A drive train (10) for a motor vehicle, wherein: The drive train (10) comprises at least one first electric motor (EM1) configured to provide a first drive torque, a second electric motor (EM2) configured to provide a second drive torque, a first driven axle (20), a second driven axle (22) and a distribution transmission (12), wherein the distribution transmission (12) is configured to selectively transmit the first drive torque and the second drive torque to the two driven axles (20, 22) in a first transmission ratio or at least one second transmission ratio different from the first transmission ratio.

2. The drive train (10) according to claim 1, characterized in that The distribution transmission (12) has a single input shaft (14) with a first end and a second end, wherein the first electric machine (EM1) can be coupled to the first end and the second electric machine (EM2) can be coupled to the second end.

3. The drive train (10) according to claim 2, characterized in that The motor shaft of the first electric motor (EM1) is permanently connected to the input shaft (14) of the distribution transmission (12) in a rotationally fixed manner, and the motor shaft of the second electric motor (EM2) is permanently connected to the input shaft (14) of the distribution transmission (12) in a rotationally fixed manner.

4. Drive train (10) according to any one of the preceding claims, characterized in that The distributing transmission (12) has a first output shaft (16) that can be coupled to the first driven axle (20), and the distributing transmission (12) has a second output shaft (18) that can be coupled to the second driven axle (22).

5. Drive train (10) according to any one of the preceding claims, characterized in that The two output shafts (16, 18) of the distribution gear (12) are arranged coaxially with each other.

6. The drive train (10) according to claim 4, characterized in that The two output shafts (16, 18) of the distribution transmission (12) are arranged in an axially parallel and offset manner with respect to each other.

7. The drive train (10) according to any one of claims 1 to 3, characterized in that The distributor transmission (12) has a single output shaft that can be coupled to the first driven axle (20) and the second driven axle (22).

8. Drive train (10) according to any one of the preceding claims, characterized in that The two electric machines (EM1, EM2) are designed for the same speed range.

9. Drive train (10) according to any one of the preceding claims, characterized in that The drive train (10) has a third driven axle (24), wherein the distribution transmission (12) is designed to also selectively transmit the first drive torque and the second drive torque to the third driven axle (24) in the first transmission ratio or the second transmission ratio.

10. The drive train (10) according to claim 9, characterized in that The drive train (10) is designed to transmit a drive torque from the distributor gear (12) jointly to the second driven axle (22) and the third driven axle (24).

11. The drive train (10) according to claim 9 or 10, characterized in that The drive train (10) has a fourth driven axle (26), wherein the distribution transmission (12) is designed to also selectively transmit the first drive torque and the second drive torque to the fourth driven axle (26) in the first transmission ratio or the second transmission ratio.

12. The drive train (10) according to claim 11, characterized in that The drive train (10) is designed to transmit a drive torque from the distributor gear (12) jointly to the first driven axle (20) and the fourth driven axle (26).

13. A motor vehicle having a drive train (10) according to any one of the preceding claims, characterized in that The drive train (10) is configured to provide driving force for the motor vehicle.

14. The motor vehicle according to claim 13, characterized in that The motor vehicle has a further electric machine which is designed to drive auxiliary consumers.

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