Siemens VDO Highlights Work with the Electronic Wedge Brake
26 September 2005
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| Siemens EWB |
Siemens VDO Automotive used the Frankfurt IAA to exhibit its work with the electronic wedge brake (EWB) which will be the foundation of its brake-by-wire systems for the 12-volt vehicle electrical system due for production in this decade.
The EWB eliminates the need for components such as hydraulic pipes, brake cylinders, brake boosters or antilock braking control units. This lowers overall weight and provides greater reliability, with reduced servicing requirements. By doing away with the hydraulic braking system, it also helps to reduce the vehicle’s environmental impact.
Siemens VDO’s EWB is based on technology developed by eStop, a firm Siemens acquired in early 2005, and its control-related foundations originate from German Aviation and Aerospace Center applications.
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| Cross section through the Electronic Wedge Brake (eStop’s mechanatronic brake) |
Vehicles employing the EWB will have an intelligent wheel-braking module fitted on each wheel. The module consists of the brake pad, the wedge attached to the wedge-bearing mechanism, the mechanical power transmission between the two electric motors and a sensor system for monitoring movement and force.
The sensors measure current wheel speed approximately one hundred times per second and braking forces and wedge position to a high degree of accuracy and resolution. When the driver engages the brake pedal, the EWB system electronically transmits the activation signal to the interconnected brake modules. When the brake activation signal is received, electric motors actuate a wedge-bearing mechanism consisting of several rollers to move the wedge into the required position according to the sensor feedback values. This causes the brake pad to be pressed against the brake disk.
Based on the principle of self-energization, the braking effect builds up very rapidly and the intelligent control prevents any danger of the wedge blocking. This principle of unstable control structures was taken from high safety-critical systems for aviation and aerospace applications and adapted for automotive purposes.
The use of the traditional 12-volt vehicle electrical system opens up new design potential for the automobile manufacturer, as the hydraulic-free wedge brake takes up less space both in the engine compartment and in the chassis. At the same time, it reduces assembly times on the production line and the number of components required for the brake. The electronic brake system also can be adapted more easily and faster to new types of vehicle helping to save time and development costs.
Resources:
eBrake: the mechanatronic wedge brake, SAE paper 2002-01-2582
Testing the Mechanatronic Wedge Brake, SAE paper 2004-01-2766
Sweet. So...
* Can this be used with regenerative braking as well?
* What are the worst case failure scenarios? Are they more or less likely than current braking systems?
Posted by: stomv | 26 September 2005 at 03:22 PM
I've had an alternator fail and and my battery die during a drive. I wonder what happens to these brakes in case of electrical system failure?
Posted by: tthoms | 26 September 2005 at 04:33 PM
Shift into neutral and pray?
Posted by: ben | 26 September 2005 at 07:19 PM
Erm, should shift to gear 1 and enable some engine braking effect. Also, you might want to try hand brake.
Posted by: rexis | 26 September 2005 at 08:20 PM
The same way you handle it if your brakes fail... your emergency brake. Thats what its there for.
Posted by: wintermane | 27 September 2005 at 12:48 AM
* Can this be used with regenerative braking as well?
Yes Stomv it can. Regenerative braking actually has very little to do with the brakes. It's actually a function that happens within the motor and transmission of the car. The brakes can be any kind you want. The Hybrid Car site has a good write up on the technical aspects if you're interested, click here.
Posted by: Jamison | 27 September 2005 at 09:34 AM
I'd like it better if the motors worked against a spring to release the brakes instead.
that way a loss of electrical power would automatically stop the vehicle. This is how air brakes work. Better to have a car stop when you don't want it to than not stop when want to.
Posted by: tom | 27 September 2005 at 12:45 PM
I am master student in mechanical engineering in Eastern Mediterranean University I am working on Brake by wire I want to know do you have any references to help me more in this way or a company that i share my improvment with them
thanks for your attention
sincerely yours;
Posted by: Sepanta | 31 October 2005 at 03:21 AM
hi am happy to vist this page.Brake by wire is a great step forward. i live in kenya and i have never seen this kind of a car. why can i get more information about this kind of a car?
Posted by: sammy arnord | 18 November 2005 at 03:35 AM