DE-102022206311-B4 - Drive system for an electrically powered vehicle

Abstract

The invention relates to a drive system for a vehicle with a primary electric drive axle and a secondary electric drive axle 1, comprising an electric drive 2, a transmission 3, a differential 4, two wheels 5, and two wet service brakes 6. The electric drive 2 is connected to an input of the differential 4 via the transmission 3. The wheels 5 are each connected to an output of the differential 4 via one of the two wet service brakes 6. Each of the two wet service brakes 6 is assigned an actuator 7 for controllable brake actuation, and a disconnect device 8 is provided between the electric drive 2 and at least one of the wet service brakes 6. The drive system according to the invention is characterized in that the disconnect devices 8 are each connected to and actuated by one of the actuators 7. The invention further relates to a vehicle with a primary electric drive axle and a secondary electric drive axle 1, which has a drive system according to the invention.

Inventors

• Matthias Müller-Linkowitsch
• Daniel Martin
• Wolfgang Barth
• Christian SIBLA

Assignees

• ZF FRIEDRICHSHAFEN AG

Dates

Publication Date

20260513

Application Date

20220623

Claims (8)

1. Drive system for a vehicle with a primary electric drive axle and a secondary electric drive axle (1), comprising an electric drive (2), a transmission (3), a differential (4), two wheels (5) and two wet service brakes (6), wherein - the electric drive (2) is connected via the transmission (3) to an input of the differential (4), - the wheels (5) are each connected via one of the two wet service brakes (6) to an output of the differential (4), - each of the two wet service brakes (6) is assigned an actuator (7) for controllable brake actuation, and - a disconnecting device (8) is provided between the electric drive (2) and at least one of the wet service brakes (6), characterized in that - the disconnecting devices (8) are each connected to and actuated by one of the actuators (7).
2. drive system according to Claim 1 , characterized in that each of the actuators (7) is hydraulically controllable.
3. drive system Claim 2 , characterized in that at least one hydraulic brake system (9) is provided which is designed to control at least one of the actuators (7).
4. Drive system according to one of the preceding claims, characterized in that the wet-running service brakes (6) are designed as oil bath-based lamellar wet brakes.
5. drive system according to Claim 4 , characterized in that at least one of the wet-running service brakes (6) and at least one of the actuators (7) are arranged in a common housing, so that they share a common oil supply.
6. drive system according to one of the Claims 1 until 3 , characterized in that the wet-running service brakes (6) are designed as fluid-cooled lamellar wet brakes.
7. Drive system according to one of the preceding claims, characterized in that each of the actuators (7) is located between a service brake area (B), within which it is connected to one of the wet service brakes (6), a separation area (C), in which it with one of the separating devices (8), and a neutral range (N) between the service brake range (B) and the separation range (C) in which the respective actuator (7) is not in contact with either one of the wet service brakes (6) or with one of the separating devices (8), is adjustable.
8. Vehicle with a primary electric drive axle and a secondary electric drive axle (1), wherein the secondary electric drive axle (1) comprises a drive system according to one of the preceding claims.

Description

The invention relates to a drive system for a vehicle with a primary electric drive axle and a secondary electric drive axle according to the preamble of claim 1, and to a vehicle therewith. The drive system is particularly suitable for motor vehicles such as passenger cars, vans, etc. The field of application of the invention lies particularly in the automotive industry in the field of electric or hybrid vehicles. The performance of electric or hybrid vehicles can be increased by better linking synergy effects between the service braking system and the drive system by utilizing energy recovery (recuperation braking, or recuperation for short) in order to recharge the energy storage (accumulator, or battery for short) or to convert excess heat energy from the drive and braking system or to use it for heating purposes. The state of the art in drive systems for passenger cars features either two primary electric drive axles or one primary and one secondary electric drive axle. In vehicles with one primary and one secondary electric drive axle, the primary electric drive axle is mainly used for propulsion, braking, and recuperation, while the secondary electric drive axle is only operated as a motor or generator under very high performance demands and/or when all-wheel drive is required. The secondary electric drive axle experiences drag losses at the bearings and gears, as well as magnetic field losses from the electric motor. These losses, especially during towing operation when the car is rolling without accelerating, cause unwanted braking. This is particularly true when recuperation is not desired, for example, when the battery is already fully charged, resulting in unintended braking of the vehicle. In normal driving conditions, where maximum power and all-wheel drive are not required, the secondary electric drive axle, also known as the all-wheel drive axle, is decoupled from the electric drive via a mechanically, electronically, or hydraulically actuated disconnect unit (DCU). This prevents drag losses at the secondary electric drive axle. Ideally, the disconnect unit is positioned very close to a wheel. In practical applications, electrically powered vehicles also employ a service braking system with one service brake per wheel. These service brakes may include an actuator designed to operate the service brake. This actuator can simultaneously operate a parking brake and may have various positions in which the parking brake and/or the service brake are engaged, or in which the actuator is neither connected to the service brake nor the parking brake. If a disconnecting device is also present on the secondary electric drive axle, the prior art always requires an additional actuator for operating the disconnecting device. This causes additional effort and costs in the manufacturing of the secondary electric drive axle and requires additional installation space. The additional actuator must also be integrated into and synchronized with the existing systems. The object of the invention is to provide a drive system for a vehicle with a primary electric drive axle and a secondary electric drive axle, in which the secondary electric drive axle can be decoupled without requiring an additional actuator for actuating each disconnecting device. The object of the invention is achieved by the features of the independent patent claims. Advantageous embodiments are specified in the dependent patent claims. According to the invention, a vehicle with a primary electric drive axle and a secondary electric drive axle, comprising an electric drive, a transmission, a differential, two wheels, and two wet service brakes, is connected via the transmission to an input of the differential, each wheel is connected via one of the two wet service brakes to an output of the differential, each of the two wet service brakes is assigned an actuator for controllable brake actuation, and a disconnect device is provided between the electric drive and at least one of the wet service brakes, in that the disconnect devices are each connected to and actuated by one of the actuators. By connecting the separating device to an actuator that also operates one of the wet-running service brakes, no additional actuator is required for the separating device. This saves effort and costs in manufacturing, and the drive system requires less installation space. The design of the primary electric drive shaft is immaterial to the invention. It can be implemented according to the prior art and can also be driven non-electrically. The design of the separating device is also immaterial to the invention. It can, for example, be implemented as a positive-locking claw or according to another prior art design. The secondary electric drive axle can, in particular, be the rear drive axle or the rear axle of a vehicle with two drive axles. Each disconnecting device is designed to disconnect and/or reconnect the connection between a wet service brake and a wheel to