25-07-2012, 11:57 AM
ELECTRONIC WEDGE BRAKE
[attachment=28836]
INTRODUCTION
Electronic wedge brake (EWB) brake-by-wire technology as the answer to future vehicle chassis safety, weight, reliability, and space requirements.
The EWB is a self-reinforcing electromechanical wedge brake, which operates around the point of maximum self-reinforcement, in order to minimize actuation forces to levels that can be supported by 12V vehicle electrical systems.
THEORY
The electronic wedge brake works by a similar principle to that used in brakes for horse-drawn carriages, where a wedge was used to bring the wheel to a standstill.
The wedge uses a vehicle’s kinetic energy, converting it into braking energy. By reinforcing itself this way, the EWB needs only one tenth of the actuating energy required by today's hydraulic braking systems.
COMPARISON
Conventional ABS takes between 140 and 170 milliseconds to generate full braking power, the EWB needs only about 100 milliseconds and therefore shortens the braking distance because a car covers the distance of 1.40 meters in one second at a speed of 100 kilometers per hour.
The wedge brake will play an important role in making it possible for drivers to keep vehicles under control even in difficult situations.
Conventional Brake:
Brake calliper
Brake booster
ESP
Brake pedal
Hand brake
Vacuum pump
Hydraulic line
Wedge Brake
EWB calliper
Backup batteries
e-pedal
Main brake controller
Cable harness
The electronic wedge brake (EWB) is a brake-by-wire system with a dry actuator at each wheel.
The strong self-reinforcement resulting from the wedge principle leads to comparatively low power consumption of the actuators.
Major advantages as compared to conventional hydraulic brake systems are
Higher dynamics leading to shorter braking distance
Reduced space requirements
Personalization of the brake pedal feel
Extended diagnostic possibilities
EWB uses motors to move a wedged plate along the longitudinal axis of the vehicle.
This plate moves rollers that fit into the similarly-wedged back plate of the brake pad.
As the wedges tighten against each other, the force of the vehicle’s forward momentum actually presses the pad tightly against the brake disc, rather than hydraulic pressure.
This system achieves vastly improved stopping power over traditional hydraulic systems with the additional benefit of significant weight and power savings.
ELECTRONIC WEDGE BRAKES OUTPERFORM HYDRAULICS
Electronic Wedge Brake (EWB) performs better than today’s hydraulic braking systems, achieving about 15 percent shorter braking distances on ice.
The average braking distance from a speed of 80 km/h on roughened ice, 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.
Siemens' Electronic Wedge Brake
Siemens has been working on a revolutionary braking system powered not by hydraulics, but by electric brushless motors. Known as the electronic wedge brake (EWB),
This innovative brake design is similar in design to standard disc brakes, in that the stopping action is achieved by pressing a brake pad against the disc.
The mechanism by which the squeezing action occurs, however, is completely different.
ADVANTAGES
Faster and more effective
The intelligently controlled wedge converts the kinetic energy of the vehicle directly into braking energy.
A vehicle with EWB has a separate intelligent brake module at each wheel.
The sensors measure the speed of each wheel about one hundred times per second.
The intelligent controls eliminate any risk of the wedge unintentionally locking up the brakes.
Fewer components, lower costs
The EWB design eliminates components such as hydraulic lines
Brake cylinders
Brake booster
ABS control unit
To offer overall system weight reduction—with simplified service
Greater reliability
Increased safety
CONCLUSION
EWB uses motors to move a wedged plate along the longitudinal axis of the vehicle. This plate moves rollers that fit into the similarly-wedged back plate of the brake pad. As the wedges tighten against each other, the force of the vehicle’s forward momentum actually presses the pad tightly against the brake disc, rather than hydraulic pressure. This system achieves vastly improved stopping power over traditional hydraulic systems with the additional benefit of significant weight and power savings.
[attachment=28836]
INTRODUCTION
Electronic wedge brake (EWB) brake-by-wire technology as the answer to future vehicle chassis safety, weight, reliability, and space requirements.
The EWB is a self-reinforcing electromechanical wedge brake, which operates around the point of maximum self-reinforcement, in order to minimize actuation forces to levels that can be supported by 12V vehicle electrical systems.
THEORY
The electronic wedge brake works by a similar principle to that used in brakes for horse-drawn carriages, where a wedge was used to bring the wheel to a standstill.
The wedge uses a vehicle’s kinetic energy, converting it into braking energy. By reinforcing itself this way, the EWB needs only one tenth of the actuating energy required by today's hydraulic braking systems.
COMPARISON
Conventional ABS takes between 140 and 170 milliseconds to generate full braking power, the EWB needs only about 100 milliseconds and therefore shortens the braking distance because a car covers the distance of 1.40 meters in one second at a speed of 100 kilometers per hour.
The wedge brake will play an important role in making it possible for drivers to keep vehicles under control even in difficult situations.
Conventional Brake:
Brake calliper
Brake booster
ESP
Brake pedal
Hand brake
Vacuum pump
Hydraulic line
Wedge Brake
EWB calliper
Backup batteries
e-pedal
Main brake controller
Cable harness
The electronic wedge brake (EWB) is a brake-by-wire system with a dry actuator at each wheel.
The strong self-reinforcement resulting from the wedge principle leads to comparatively low power consumption of the actuators.
Major advantages as compared to conventional hydraulic brake systems are
Higher dynamics leading to shorter braking distance
Reduced space requirements
Personalization of the brake pedal feel
Extended diagnostic possibilities
EWB uses motors to move a wedged plate along the longitudinal axis of the vehicle.
This plate moves rollers that fit into the similarly-wedged back plate of the brake pad.
As the wedges tighten against each other, the force of the vehicle’s forward momentum actually presses the pad tightly against the brake disc, rather than hydraulic pressure.
This system achieves vastly improved stopping power over traditional hydraulic systems with the additional benefit of significant weight and power savings.
ELECTRONIC WEDGE BRAKES OUTPERFORM HYDRAULICS
Electronic Wedge Brake (EWB) performs better than today’s hydraulic braking systems, achieving about 15 percent shorter braking distances on ice.
The average braking distance from a speed of 80 km/h on roughened ice, 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.
Siemens' Electronic Wedge Brake
Siemens has been working on a revolutionary braking system powered not by hydraulics, but by electric brushless motors. Known as the electronic wedge brake (EWB),
This innovative brake design is similar in design to standard disc brakes, in that the stopping action is achieved by pressing a brake pad against the disc.
The mechanism by which the squeezing action occurs, however, is completely different.
ADVANTAGES
Faster and more effective
The intelligently controlled wedge converts the kinetic energy of the vehicle directly into braking energy.
A vehicle with EWB has a separate intelligent brake module at each wheel.
The sensors measure the speed of each wheel about one hundred times per second.
The intelligent controls eliminate any risk of the wedge unintentionally locking up the brakes.
Fewer components, lower costs
The EWB design eliminates components such as hydraulic lines
Brake cylinders
Brake booster
ABS control unit
To offer overall system weight reduction—with simplified service
Greater reliability
Increased safety
CONCLUSION
EWB uses motors to move a wedged plate along the longitudinal axis of the vehicle. This plate moves rollers that fit into the similarly-wedged back plate of the brake pad. As the wedges tighten against each other, the force of the vehicle’s forward momentum actually presses the pad tightly against the brake disc, rather than hydraulic pressure. This system achieves vastly improved stopping power over traditional hydraulic systems with the additional benefit of significant weight and power savings.