Drive arrangement for a vehicle with an electric machine and method for operating the vehicle

Abstract

Drive arrangement (1) for a vehicle with an electric machine (2), a two-stage transmission (15) downstream of the electric machine (2), wherein the electric machine (2) can be connected to an axle shaft (7) of the vehicle via the transmission (15), wherein the transmission (15) has an input shaft (9) connected to a rotor shaft of the electric machine and an output shaft (12) connected to the axle shaft (7) of the vehicle, wherein the input shaft (9) can be connected to the output shaft (12) via a gear (10b) of the first gear stage or a gear (10a) of the second gear stage by actuating a first multi-plate clutch (6a) associated with the first gear stage or a second multi-plate clutch (6b) associated with the second gear stage, and wherein the transmission (15) implements a braking function, wherein the braking function can be activated in such a way thatthat the first multi-plate clutch (6a) and the second multi-plate clutch (6b) in the gearbox (15) are actuated simultaneously and are therefore at least partially closed at the same time.

Description

[0001] The invention relates to a drive arrangement for a vehicle with an electric machine and a two-stage transmission connected downstream of the electric machine. The invention also relates to a method for operating a vehicle. State of the art

[0002] In passenger cars, according to the state of the art, each wheel is coupled with its own brake. A car that typically has four wheels thus has four individual brakes. The braking system and the drive system are separate systems. This applies to both conventionally and electrically powered cars. A special feature of electrically powered cars is that the electric motor, in generator mode, can contribute a significant braking torque, which varies depending on the situation, in addition to the wheel brakes.

[0003] Current braking systems in passenger cars usually feature dry-running disc or drum brakes, which, in addition to the ongoing maintenance and service costs due to wear and corrosion, are also largely responsible for particulate emissions, which are already regulated starting with EURO 7. In addition to a torque vectoring unit, modern drive systems also feature powershift multi-speed transmissions, which, however, are not used to implement the braking function.

[0004] DE10 2021 205 073 A1 discloses a passenger car with electric rear-wheel drive, comprising a drive system including power electronics, an electric motor, a transmission gear, and a differential gear, together forming an electric axle, and two side shafts connected to the differential gear, each with a rear wheel attached to its free end, and a braking system. Since the braking system has a central brake arranged within the electric axle between the electric motor and the differential gear, an electrically powered passenger car is provided, in which the electric motor acts on the rear axle, with a simplified braking system on the driven rear axle.

[0005] AT 520 430 A4 shows a brake disc system for the vehicle drive axle. The differential function is implemented by one drive assembly per vehicle wheel. This allows the drive side to be braked or locked during braking. The braking power can be distributed between the drive-side assembly and those on the wheel side. The wheel-side assembly is preferably operated with slip to ensure individual control of the wheels.

[0006] DE 10 2017 114 481 B3 shows a planetary gear with two clutches, each of which engages a sun gear.

[0007] DE 10 2020 112 624 A1 also shows a planetary gear with a brake on each of the ring gears. The braking function allows gear shifting.

[0008] DE 10 2021 202 258 A1 shows an electric drive with a planetary gear with two switching elements, which can also be designed as multi-plate clutches.

[0009] The object of the invention is to present an improved drive system with improved integrated braking function and torque distribution. Description of the invention

[0010] The problem is solved by a drive arrangement for a vehicle with an electric machine, a two-stage transmission downstream of the electric machine, wherein the electric machine can be drive-connected to an axle of the motor vehicle via the transmission, wherein the transmission has an input shaft drive-connected to a rotor shaft of the electric machine and an output shaft drive-connected to the axle of the motor vehicle, wherein the input shaft can be drive-connected to the output shaft via a first gear stage or a second gear stage by actuating a first multi-plate clutch assigned to the first gear stage or a second multi-plate clutch assigned to the second gear stage, wherein gear wheels on the input shaft mesh with their corresponding gear wheels, which are seated as idler gears on the output shaft, and wherein the transmission implements a braking function, wherein the braking function can be activated in such a way thatthat the first multi-plate clutch and the second multi-plate clutch are actuated simultaneously and are thus at least partially closed.

[0011] The output of the transmission is connected to an axle shaft of the vehicle via a drive wheel, whereby the axle shaft is interrupted to the left wheel and the right wheel and can be connected via a multi-plate clutch in each case.

[0012] The transmission is powershiftable.

[0013] The multi-plate clutches are operated via electric actuators.

[0014] The object is also achieved by a method for operating a motor vehicle with an electric machine and a two-stage transmission connected downstream of the electric machine, which is powershiftable and has two gear stages and two multi-plate clutches for actuating the two gear stages, wherein, in order to increase the braking effect of the vehicle, in addition to the actuation of the multi-plate clutches on the axle shaft, both multi-plate clutches on the drive shaft are also actuated simultaneously in order to generate a braking function by tensioning the two-stage transmission.

[0015] The inventive solution provides a maintenance-free, wet-running braking system integrated into an electric drive. Its design meets the power loss requirements required for electric vehicles and integrates torque distribution and a powershift two-speed transmission. This drive system generates an additional braking torque in addition to the braking torque of the electric motor by engaging the powershift multi-speed transmission. Description of the characters

[0016] Fig. Figure 1 shows an electric drive assembly 1 for a motor vehicle, of which only the left wheel 3a and the right wheel 3b are shown. These are mounted on a split axle shaft 7, with the axle shaft sections 7a and 7b being connectable to a drive wheel 8 via multi-plate clutches 5a and 5b.

[0017] An electric machine 2 with its inverter 4 is installed such that the drive shaft of the electric machine 2 runs parallel to the axle shaft 7 as an input shaft 9, a continuation of the rotor shaft. Gear wheels 10a, 10b for a first and a second gear are installed on the drive shaft 9 of the gearbox 15 of the electric machine 2. The gear wheels 10a and 10b mesh with their corresponding gear wheels 11a and 11b, which are mounted as idler gears on the output shaft 12. The idler gears 11a and 11b are actuated via the multi-plate clutches 6a and 6b. The output shaft 12 carries a gear 13 that meshes with the drive gear 8 of the axle shaft 7.

[0018] The embodiment thus shows a two-stage transmission 15, wherein the electric machine 2 can be connected to the axle shaft 7 of the vehicle via the transmission 15.

[0019] The transmission is switched to load-free mode by closing and opening the multi-plate clutches 6a and 6b in a cross-fading manner.

[0020] The torque of the electric motor 2 is then transmitted to the drive wheel 8 and the axle shaft 7 via the engaged gear. The two multi-plate clutches 5a and 5b then represent a differential function and can distribute the torque through appropriate actuation.

[0021] To brake the drive system, the two multi-plate clutches 5a and 5b on the axle shaft 7 are closed to connect the wheels to the electric motor. The electric motor 2 recuperates and thus generates a braking torque. The two multi-plate clutches 6a and 6b are partially closed together to clamp the transmission 15. This clamping creates a further braking torque.

Claims

[1] Drive arrangement (1) for a vehicle with an electric machine (2), a two-stage transmission (15) connected downstream of the electric machine (2), which is power-shiftable, wherein the electric machine (2) is driveably connected to an axle shaft (7) of the vehicle via the transmission (15), wherein the transmission (15) has an input shaft (9) drive-connected to a rotor shaft of the electric machine and an output shaft (12) drive-connected to the axle shaft (7) of the vehicle, wherein the input shaft (9) can be drive-connected to the output shaft (12) via a gear wheel (10b) of the first gear stage or a gear wheel (10a) of the second gear stage by actuating a first multi-plate clutch (6a) assigned to the first gear stage or a second multi-plate clutch (6b) assigned to the second gear stage, wherein gear wheels (10a and 10b) on the drive shaft (9) are connected to their corresponding gear wheels (11a and 11b),which are seated as idler gears on the output shaft (12), mesh, and wherein the transmission (15) implements a braking function, wherein the braking function can be activated such that the first multi-disk clutch (6a) and the second multi-disk clutch (6b) in the transmission (15) are actuated simultaneously and are thus at least partially closed at the same time. [2] Drive arrangement (1) according to claim 1, characterized by that the output of the transmission (15) is connected to the axle shaft (7) of the vehicle via a drive wheel (8), wherein the axle shaft (7) is interrupted to the left wheel (3a) and to the right wheel (3b) and can be connected via a respective multi-plate clutch (5a, 5b). [3] Drive arrangement according to claim 1 or 2, characterized by that the transmission is powershiftable. [4] Drive arrangement according to one of the preceding claims, characterized by that the multi-plate clutches (5a and 5b) on the axle shaft are closed for braking. [5] Drive arrangement according to one of the preceding claims, characterized by that the multi-plate clutches (6a, 6b, 5a, 5b) are actuated via electric actuators. [6] Method for operating a vehicle with a drive arrangement according to one of claims 1 to 5 with an electric machine (2) and a two-stage transmission (15) connected downstream of the electric machine (2), which transmission is power-shiftable and has two gear stages and two multi-plate clutches (6a, 6b) for actuating the two gear stages, wherein, in order to increase the braking effect of the vehicle, in addition to the actuation of the multi-plate clutches (5a, 5b) on the axle shaft (7), both multi-plate clutches (6a, 6b) on the output shaft (12) are also actuated simultaneously in order to generate an additional braking function by tensioning the two-stage transmission (15).

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