A vehicle’s brakes and the connection between the wheels and engine – typically a clutch or torque converter – have traditionally been separate components. But according to a patent filed by Audi with the European Patent Office, the German automaker proposes integrating both into a single device. Here’s how it would work.
One Device Transmits Torque And Braking Forces
Audi’s device looks like an old-fashioned drum brake, with an input shaft on one side and an output shaft on the other. The input receives engine power – either directly or from the transmission – and the output shaft is attached to the wheel. Inside the housing, a torque-transmission mechanism comprising overlapping plates actuated via electromechanical or hydraulic actuators enables the device to vary how much torque reaches the output shaft.
If the clutches are open, the drive is disconnected, and if they are locked, both shafts spin at the same speed. The clutch pack varies the amount of torque being transmitted, and can also transmit a braking torque to slow the wheel down, effectively replacing the brake on that wheel. The clutch packs can be arranged inline or nested, depending on the available space.
Uses, Implications, and Advantages
Units can be fitted to all driveshaft on multiple axles to control torque transmission and braking forces per wheel, so a vehicle won’t need a separate drive-decoupling device anymore, nor a brake for each wheel to which the device is fitted. The device can act as a torque splitter between wheels, in the fashion of a torque-vectoring differential.
Combining torque-transmission and brake functions per wheel has several advantages:
- Weight/space saving by combining the brake and the clutch
- Better efficiency due to precisely controlled slip losses and lower weight
- More compact driveline packaging
- Lower unsprung mass because the brake is removed from the wheel
Question Marks
Mass adoption would depend on the seamless integration of the device. While the advantages of the finely controlled torque transmission per wheel are readily apparent, the system must be engineered to reliably withstand the heat, wear, and fade that go with heavy brake application in fast driving or heavy vehicles. If these problems can be overcome, the device could change the way powertrains are designed and packaged.
