Drivetrain for a Vehicle

Abstract

A drivetrain for a vehicle includes a drive motor, an axle differential, and a friction brake. The drive motor is configured to drive the axle differential. The friction brake is positioned in a transmission path between the drive motor and the axle differential, and is configured to generate a braking torque.

Claims

1. A drivetrain for a vehicle, comprising: an axle differential; a drive motor configured to drive the axle differential; and a friction brake positioned in a transmission path between the drive motor and the axle differential, and configured to generate an adjustable braking torque that acts within the drivetrain.

2. The drivetrain of claim 1, further comprising: a transmission positioned downstream of the drive motor, wherein the friction brake is positioned either upstream or downstream of the transmission.

3. The drivetrain of claim 1, wherein the drive motor is an electric motor.

4. The drivetrain of claim 1, wherein the drive motor is an internal combustion engine.

5. The drivetrain of claim 1, wherein the friction brake is adjustable between (i) a functional position that enables a maximum braking torque and (ii) a reduction position that enables a reduced braking torque or no braking torque.

6. The drivetrain of claim 5, further comprising: an actuator assigned to the friction brake for adjustment between the functional position and the reduced position.

7. The drivetrain of claim 5, wherein the friction brake is configured to move between the functional position and the reduced position in response to a centrifugal force.

8. The drivetrain of claim 1, wherein either: (i) the drivetrain further comprises an actuator operable to adjust a level of the braking torque generated by the friction brake; or (ii) the friction brake is configured such that the level of the braking torque generated by the friction brake is manually adjustable.

9. The drivetrain of claim 1, wherein the friction brake is operable as a parking brake and is configured to fix the vehicle at a standstill.

10. The drivetrain of claim 1, wherein the friction brake includes a separate friction brake housing.

11. A vehicle, comprising: a drivetrain, including: an axle differential; a drive motor configured to drive the axle differential; and a friction brake positioned in a transmission path between the drive motor and the axle differential, and configured to generate an adjustable braking torque that acts within the drivetrain.

12. The vehicle of claim 11, further comprising: wheel brakes positioned in the drivetrain in addition to the friction brake.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further advantages and expedient embodiments can be inferred from the further claims, the description of the figures and the drawings. In the drawings:

[0030] FIG. 1 shows a schematic representation of a drivetrain in a vehicle with a drive motor, a transmission, a friction brake and an axle differential on the axle with the driven wheels,

[0031] FIG. 2 shows a schematic diagram of an actuating apparatus of the friction brake which is located in the functional position in which a maximum braking torque can be generated,

[0032] FIG. 3 shows a representation corresponding to FIG. 2 of the friction brake which is, however, located in a reduction position in which only a reduced braking torque can be generated,

[0033] FIG. 4 shows a schematic diagram of the friction brake with a brake band which is wound around a brake drum, represented in the functional position,

[0034] FIG. 5 shows a representation corresponding to FIG. 4 with the friction brake in the reduction position.

DETAILED DESCRIPTION

[0035] Identical components are provided with identical reference numbers in the figures.

[0036] A drivetrain 1 for a motor vehicle is represented schematically in FIG. 1. Drivetrain 1 comprises a drive motor 2, a transmission 3, a friction brake 4 and an axle differential 5 which sits on a vehicle axle 6, which is a carrier of a left and right driven vehicle wheel 7 or 8.

[0037] Drive motor 2 drives transmission 3 via a shaft 9, which transmission 3 is connected via a further shaft 10 to the friction brake which is in turn connected via a further shaft 11 to axle differential 5. Shaft 9 forms the output shaft of drive motor 2 and at the same time the input shaft of transmission 3. Shaft 10 forms the output shaft of transmission 3 and at the same time the input shaft of friction brake 4. Shaft 11 forms the output shaft of friction brake 4 and at the same time the input shaft of axle differential 5.

[0038] Wheel brakes 12 and 13 sit on the vehicle wheels. This involves in particular a hydraulic vehicle brake.

[0039] Friction brake 4 can also, where applicable, be arranged between drive motor 2 and transmission 3.

[0040] Friction brake 4 primarily has the function of a parking brake in order to fix the vehicle permanently at a standstill. To this end, friction brake 4 generates, at a standstill of the vehicle, a braking torque which counteracts any driving torque, which originates from vehicle wheels 7, 8, for example, as result of parking of the vehicle on a steep road. The braking torque is advantageously generated via friction brake 4 only at a standstill of the vehicle or in the case of a vehicle speed below a speed threshold value of, for example, 3 km/h. Where applicable, however, the braking torque in friction brake 4 can also be used at higher vehicle speeds in order to assist vehicle brake 12, 13.

[0041] Drive motor 2 is, for example, an internal combustion engine. Alternatively, an electric motor is also possible as drive motor 2. In the case of an electric motor, a transmission 3 can also be provided. In an alternative embodiment, in the case of an electric motor as drive motor 2, such a transmission 3 can be omitted. In this case, friction brake 4 sits directly between the electric motor as drive motor 2 and axle differential 5.

[0042] Friction brake 4 is to be adjusted between a functional position, which is represented in FIGS. 2 and 4, and a reduction position, which is represented in FIGS. 3 and 5. In the functional position according to FIGS. 2 and 4, where necessary, a maximum braking torque can be generated in friction brake 4, advantageously in continuous gradation between zero and the maximum braking torque. Either no braking torque or only a reduced braking torque can in contrast be generated in friction brake 4 in the reduction position according to FIGS. 3 and 5. In the event that friction brake 4 is used as a parking brake, friction brake 4 assumes the reduction position in all speeds above the threshold speed of, for example, 3 km/h. This means that the maximum braking torque which is generated for permanent fixing of the vehicle can only be generated if the vehicle speed lies below the threshold speed.

[0043] Adjustment between the functional position and the reduction position is carried out with the aid of an actuation unit 17 (FIGS. 2, 3) which is formed either passively, for example, as a centrifugal element, or actively, for example, as an actuator. Actuation unit 17 acts on a bearing 16 to which a brake band 14 is fastened which is placed around brake drum 15 as a component of friction brake 4 (FIGS. 4, 5). Brake drum 15 is connected fixedly to a shaft in the drivetrain so that a braking torque is generated in the drivetrain with the placing of brake band 14 on the outside of brake drum 15.

[0044] Bearing 16 holds brake band 14 in position. Bearing 16 is held adjustably, for example, in a guide 18, wherein actuation unit 17 adjusts bearing 16 in guide 18 between a starting position according to FIG. 2, which corresponds to the functional position, and a deflected position according to FIG. 3, which corresponds to the reduction position. As can be inferred from a comparison of FIGS. 4 and 5, bearing 16 is, in the event of a transfer from the functional position into the reduction position, raised from an initial level x.sub.0 by the amount x to a level x.sub.1 so that, in the event of equal actuation of brake band 14, no friction force or at least a significantly lower friction force is generated between brake band 14 and brake drum 15 and thus a correspondingly lower braking torque is generated. With the transfer of bearing 16 from the reduction position according to FIG. 5 into the functional position according to FIG. 4, the maximum possible friction force and the maximum possible braking torque are available again.