Electronic Wedge Brakes Outperform Hydraulics

Electronic wedge brakes being developed by Siemens VDO were tested against similar cars equipped with hydraulic brakes and the electronic brakes consistently stopped in a shorter distance. We covered electronic wedge brakes in November of last year and discussed their development as part of the Siemens eCorner concept which combines the drivetrain, steering, shock absorbers and brakes directly into the wheels of future cars. Now, though even in the prototype stage, tests already show wedge brakes offer superior performance compared to the current state-of-the-art systems.

Siemens press release follows:

Even though it is still in the prototype stage, the Siemens VDO Electronic Wedge Brake (EWB) performs better than today’s hydraulic braking systems, achieving about 15 percent shorter braking distances on ice. This was confirmed during tests on roughened ice in Arjeplog, Sweden for a DEKRA expert opinion on braking performance.

Today’s cars decelerate using hydraulic brakes and use electronics to help shorten braking distances and minimize swerving. In a comparison test with four other mid-sized vehicles, a test vehicle equipped with the Electronic Wedge Brake (EWB) achieved noticeably better braking performance without hydraulics. The average braking distance from a speed of 80 km/h on roughened ice, measured as part of a DEKRA expert opinion, was 15 percent shorter than the average braking distance of the four comparison vehicles. While the EWB test vehicle required an average of 64.5 meters to reach a full stop, the stopping distance for the vehicles with hydraulic brakes ranged from 71.8 to 78.4 meters. That means that in an emergency situation, traditional mass-produced vehicles with hydraulic brakes would still be going at a speed of 27 to 34 kilometers per hour, even after a vehicle equipped with the EWB had already come to a stop.

Schematic of the Siemens VDO Electronic Wedge Brake: The brake calipers (1) spans the brake disk (2) from two sides. The brake disk is braked by a pad (3) which is moved by an electric motor (4) by several rollers (5) along wedge-shaped inclined faces.

“This year’s ice tests have proven that the EWB prototype already outshines hydraulic brakes. With this result, we are on schedule, meaning that we will be able to provide automotive manufacturers with the Electronic Wedge Brake in 2010 as a true alternative to the hydraulic brake,,” says Bernd Gombert, Technical Chairman of the Chassis & Safety Division of Siemens VDO and thus responsible for the development of the EWB.

Link: Siemens VDO