For six days, over 3,300 kilometres and through different climate zones to the Arctic Circle: On an unusual test drive, a Bosch development team successfully tested the new hydraulic brake-by-wire system from Bosch for the first time on public roads. What sets brake-by-wire apart: This solution completely eliminates the mechanical connection between the brake pedal and the brake system. The driver’s brake request is transmitted to the brake-by-wire system purely as an electrical signal via redundant signal lines. For this fundamentally new approach, Bosch offers a robust and efficient solution with two independent hydraulic brake actuators – a by-wire brake actuator and an ESP. Today’s brake systems, such as the integrated power brake from Bosch, still ensure the required redundancy in the event of a fault via a mechanical connection to the brake pedal. This coupling via an input rod to the brake pedal is eliminated in the new Bosch brake-by-wire solution.
Bosch is working on innovative by-wire solutions for both vehicle brakes and steering – including this hydraulic brake-by-wire system, which is planned to be launched on the market from fall 2025. In addition to the hydraulic solution, Bosch is also developing a purely electromechanical system. The company has already received orders from various vehicle manufacturers and expects that by 2030, more than 5.5 million vehicles worldwide will be equipped with brake-by-wire.
Advantages of the Bosch brake-by- wire system
New freedom in installation: Due to the omission of the mechanical connection, there is no longer any need to mount the brake system components at the vehicle’s firewall. Instead, the components can now be installed where it is most optimal in terms of crash safety, NVH, and manufacturing. The flexibility in choosing where to install the brake actuators helps to avoid the need for different variants for right-hand and left-hand drive vehicles. By-wire technology enables new pedal concepts with significantly shorter brake pedal travel to create space for new interior designs. The hydraulic brake-by-wire solution from Bosch is based on proven brake system technology and is a combination of a by- wire brake actuator and an ESP. Its slim design saves installation space and reduces the weight of the brake system. Since both the by-wire brake actuator and the ESP are assigned to different channels of the redundant electrical system, they can each independently build up the required brake pressure at all four wheel brakes in the event of a fault. Therefore, this Bosch solution is also suitable for highly automated vehicles, meeting the protection of the brake system required for safety reasons.
Successful long-distance test provides valuable data for further development
The brake-by-wire system is being developed at the Bosch development centre in Abstatt near Heilbronn. The long-distance journey led the development team from the southwest of Germany via Hamburg, Copenhagen and Stockholm and a short detour to the Arctic Circle to the finish at the Bosch winter test center Vaitoudden in Arjeplog, in northern Sweden. Bosch has specifically applied for and obtained approval for public roadway use for the test vehicle in several countries, based on an extensive safety concept. “The whole team has worked towards this event with incredible motivation and is very proud of this achievement. Our hydraulic brake-by-wire system has worked perfectly on the journey. With our first long-distance test, we impressively demonstrated that we can bring a real brake-by-wire system safely and successfully from the test track to the road,” explains Hagen Kuckert, project manager for the by-wire brake actuator at Bosch in Abstatt. “We performed thousands of braking operations during the journey, were able to obtain important insights and data on the behaviour of the brake system in a wide variety of traffic situations and compare them with our previous simulations. All this is incorporated into the further development work to further optimise our hydraulic brake-by-wire system.”
