Brake pedal for regenerative braking

[Joey92]

We are building an electric car and are using regenerative braking system in our car. I am confused how do we stop the actuation of the hydraulic circuit after the brake pedal has been pressed . We are thinking of 20% brake pedal pressing before the hydraulics are actuated. Any ideas on how to stop the hydraulic actuation before 20% travel?

[MCoach]

It is possible to just...you know...not make it possible to actuate a hydraulic circuit until then. Have the first section of pedal travel actuate a potentiometer, or something else, then have it mechanically actuate the brake pedal after the first 20% of pedal travel.

[Joey92]

But when you press the brake pedal(which is connected to the master cylinder) , the fluid will be compressed and braking will take place. How to counter that ?

[Dunk Mckay]

WHat I think McCoach is saying, and what i would advice (check it's legal) Is essentially have two pedals. The main pedal your driver presses and a second one that has a 20% offset behind it. So for the first 20% of travel only on pedal is moving actuating a potentiometer at 20% it engages (hits against) with the second pedal and pushes both the potentiometer and the master cylinders.

[MCoach]

Originally posted by Dunk Mckay:
WHat I think McCoach is saying, and what i would advice (check it's legal) Is essentially have two pedals. The main pedal your driver presses and a second one that has a 20% offset behind it. So for the first 20% of travel only on pedal is moving actuating a potentiometer at 20% it engages (hits against) with the second pedal and pushes both the potentiometer and the master cylinders.


Exactly what I was suggesting. However, again, I like to also advise to see what is in fashion. What have other teams used that are legal? Now, I'm not saying copy, but get and idea what others have accepted as reasonable implementations of the concept.

[JulianH]

The question is (if you have a 2WD car at least):

Why do you want to break without actuating the mechanical braking system?

Are you able to achieve enough torque to slow the car down so that it's decelerating "fast"?
And does your driver like it if only the rear is braking?

I think Delft had a system for their 4WD car but the 2WD cars used a simple superposition of electric braking and mechanical braking (at least all the teams I talked to at FSG).