Braking force is generated at each wheel by an electric motor, i.e. without a hydraulic system and brake fluid. The brake system was developed at ZF’s development centers in China, the USA, and Germany for the global market.
In a so-called ‘dry’ brake system, brake fluid is not required any more. Brake pressure is therefore no longer generated by the pressure of fluids in the hydraulic system, but by electric motors. Brake signals from the pedal to the electric motor are also transmitted purely electrically, which is why the term ‘dry brake-by-wire’ is used.
Compared with conventional braking systems, the new brake-by-wire system, like Integrated Brake Control (IBC), enables shorter braking distances, better recovery of braking energy, and lower maintenance costs.
During automatic emergency braking, the braking distance at a speed of 100 km/h can be up to nine meters shorter than with conventional braking systems. In addition, electric cars can achieve up to 17 percent more range via even better recuperation of braking energy.
With dry brake-by-wire systems in particular, the residual drag torques that occur with conventional braking systems due to minimal contact between the brake pads and the brake discs can be reduced to almost zero. This results in even fewer particulate emissions due to brake abrasion. This lower resistance during driving also saves energy and can increase range in an EV.
Even though there is no longer a mechanical connection between the brake pedal and the brake actuators, the braking feel is the same as that of a hydraulic brake. The safety of the data transmission and processing as well as the energy supply to the electric motors is ensured by the duplication of all connections and systems, as is also common in by-wire systems in aviation.
Vehicle manufacturers can put together their optimum braking system from the classic purely hydraulic to the new purely electric braking system depending on their requirements. Hybrid forms with, for example, a hydraulic system at the front and a purely electric system on the rear axle are also possible. In addition, ZF offers all components of a braking system from a single source, from wheel brakes to parking brakes, and hardware to software.
