So you’ve got the drum brake, then the disc brake, then the disc brake with multiple calipers. Then you improve that further with slots, cross-drill holes and make the whole disc ventilated. Even brake by wire has been introduced. What next, something totally different?
Introducing the Electronic Wedge Brake (EWB), a technology by Siemens VDO, based on a concept from aerospace engineering. The Electronic Wedge Brake completely bypasses any hydraulic system, instead it is powered by a simple 12-volt power system that already exists in the car. The system also has a faster reaction time, it works about a third quicker than conventional brakes, only requiring 100ms to reach full braking power compared to a hydraulic brake’s 170ms.
Basically, a brake pad connected to a wedge is pressed between the rod and the disc through the use of electric motors. The electric motors turn and push the pad onto the disc. The use of a wedge means braking power is multiplied with minimal energy expenditure (about one tenth of hydraulic brakes), through the principle of self-energization. The faster you are going, the stronger the brake force is going to be. The lack of a physical connection between brake pedal and brakes also makes this a brake by wire system by default. Sensors measuring wheel speed about a hundred times a second can adjust brake forces and wedge position to a high degree of accuracy, somewhat like ABS and stability control rolled into one.
Test results have been amazing so far. An Audi A6 fitted with the Electronic Wedge Brake system was put to the test comparing against another A6 with conventional brakes. The braking distance required from 100 km/h to 0 km/h was reduced by half in the EWB-equipped A6!
However, all brake by wire systems make you wonder what would happen if somehow power supply were to be disrupted. Something simple like the battery going flat because the engine’s alternator malfunctioned. To take care of this, the EWB is specified to be connected to two power supplies, a main one and a backup one with a secondary battery.
This is a good advancement in braking technology. The first car with EWD is expected to debut by 2010, and it will most likely be a German marque. Might be Audi since they were testing with Audis. More photos and a video after the jump.
Video: Siemens Electronic Wedge Brake (EWB)