International automotive supplier Continental has developed a concept for an Electric Parking Brake (EPB) for drum brakes.
It is especially tailored to the lower-priced automotive segment that, up until now, has had to make do with mechanical parking brakes built into the existing drum brake on the rear axle. "By combining drum brakes and electric parking brakes, we can offer easy, push-button operation on compact cars. These cars can offer the same convenience and safety functions found on higher-priced models but at a comparatively modest cost", says Matthias Matic, Executive Vice President of the Hydraulic Brake Systems Business Unit of Continental's Chassis & Safety Division. The electric parking drum brake will go into serial production by 2017.
The system consists of two actuators which are integrated into the drum-brake base panel on the rear axle, in addition to its control software. The electronics that electrically activate the actuators of the electric parking brake are integrated into the Electronic Stability Control (ESC) system. A common construction for light compact cars, it features solid bracing for the two brake shoes, a dual-acting hydraulic cylinder for the service brake, and mechanical adjustment. "Low-priced drum brakes, built-in control elements and activation via the ESC represent a happy mixture of low weight, high efficiency and low overall costs, making them ideal for light, compact cars", says Bernhard Schmittner, head of core development foundation brakes / EPB for Continental's Chassis & Safety Division.
The functionality of the electro-mechanical system can in future also be used for the application in the duo-servo brakes common on light trucks and SUVs.
The advantages & fitment rates of electric parking brakes:
From a functional point of view electric parking drum brakes offer the same benefits as EPB versions for disc or duo-servo brakes: activation at the touch of a button, plus various assistance functions (such as starting when parked on a slope), serve to enhance convenience and safety for drivers. Carmakers enjoy new-found design freedom in car interiors because there is no longer any parking-brake lever.
"We expect the hand-brake lever to gradually disappear from more and more cars of different classes over the next ten years. Instead, the cars will be equipped with electric parking brakes", says Matic. "One car in four in Europe will feature an electric parking brake by 2015. That's more than five times as many as in 2008".
Types of electric parking brakes:
In addition to electric parking drum brakes, Continental's product range includes electric parking brakes for Duo-Servo (DS) and Caliper-Integrated (CI) disc brakes. EPB-DS are highly efficient, self-reinforcing drum brakes located in the disk pot. They are particularly prevalent in luxury cars, sports cars and SUVs. The EPB-CI is a combination of a built-in caliper and an EPB. An electronic control device integrated into the ESC system activates the brakes in all three EPB systems.
