Hello everyone,
I'am Ahmad Rezq from CURT (Cairo University Racing Team).
I'am working on the brake pedal of our new car and i have some questions
Please excuse my English
1 - Pedal Geometry
geometry.jpg1.jpg2.jpg
I uploaded to you the geometry of the pedal and my target is to see the pedal ratio change with pedal travel
a is the total pedal length, theta is the pedal angle, d is the distance between the pedal pivot the bias bar mount , c is the length of both the master cylinder rod the balance bar end , also i set a fixed point which is on the mounted point of the master cylinder to the pedal box and i draw b with an angle of fai, and then epsi angle is as illustrated.
i used pedal ratio 6 and i calculated an initial position with pedal angle = 80 deg , and i have the value of
the length c and also the value of d so i got the initial value of b,epsi and fai . then i built a matlab code which iterated the change of this geometry with the change of the pedal angle theta. my pedal ratio is the change of the pedal arc which is delta theta * a divided by the change of length c. and i attached to you 2 graphs , first one is the change of pedal ratio with pedal travel , the second is the relation between MC travel and Pedal travel. Are these calculations right ?
2 - Pedal length
my second question is about the pedal length , I know that it depends on ergonomics , and I selected 24 CM pedal. any suggestions?
3 - Pedal Travel
I'am confused a little bit about calculating the pedal travel which locks the wheels. i got an equation from brake design and safety which i used to calculate the pedal travel.
pedal_travel(cm)=0.9*car_weight(N)*deceleration(g)/f_driver.
And due to some calculations i got maximum travel = 5 cm
thanks,