Electric application of service and parking brake
Electric application of service and parking brake
(OP)
I am interested in the electric/electronic application of service/secondary braking (including parking brake) of automobiles. I am interested in how they work, how the braking force is applied and what sort of load is placed on the battery. A specific question is, with the engine switched off and the service brakes applied on and off, say 20 times, what effect would this have on the battery? How many applications would you expect to make before the battery could not fully apply the brakes?
I appreciate that the above is a bit of a tall order, but I would appreciate all and any input on this subject.
Thanks
I appreciate that the above is a bit of a tall order, but I would appreciate all and any input on this subject.
Thanks





RE: Electric application of service and parking brake
If the service brake is mechanically actuated, the electric actuator must provide the force through whatever mechanical amplifier exists (i.e. a lever). The actuator force can be calculated, then converted to a current draw for each actuation cycle. Based on the amperes required, and the duty cycle of the actuation, one could estimate how long the battery would last.
If you were attempting to provide an electric actuation of the brake, it would seem necessary to make the actuator disengage the brake while the vehicle is running. Only then would the charging system replenish the battery energy required to keep the actuator in its position. Once the vehicle were switched off, the service brake would be automatically actuated. This may not be desirable.
RE: Electric application of service and parking brake
In my opinion, for the device to be both safe as a parking brake, and as an emergency backup brake, You would need some sort of device limiting automatic application when the electricity fails when the vehicle is traveling at speed, and you would also need some sort of manual overide so the driver could still apply the brake under his complete control in an emergency created by failure of the main brake system
Regards
pat
RE: Electric application of service and parking brake
As to the energy required to activate a park brake system. It is actually defined in the ADRs or your vehicle regs, I don't know the exact figure but it would have to be less than 300N by 0.2 m, ie 60 J, ie 12V times 5 amps for 1 second, plus inefficiencies. Much of that goes in friction in the cables rather than in applying the brake. Directly actuating the system at the wheel would be 1/4 of that I guess.
Cheers
Greg Locock
RE: Electric application of service and parking brake