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Design Process and Methods
Parameters
Finding Braking efficiency under different conditions
Finding Master Cylinder Diameter
Wheelbase, mass, rotor dimensions for the Wilwood PS-1 two-piston calipers, mass height and center of the car were known. Using this information with the desired pedal force and deceleration parameters the first major calculation was Master Cylinder Diameter based and pedal geometry
Finding Master Cylinder Diameter
Finding Braking efficiency under different conditions
Finding Master Cylinder Diameter
Tables were created for all peak coefficient of friction possibilities, brake forces possible with different master cylinder sizes, and pedal geometry options that would fit in car. Iterating thru this information the leading candidate for the master cylinder diameter was .63in. With the brake gains derived, this would cover brake balance bar adjustments from .5in to 2 in
Finding Braking efficiency under different conditions
Finding Braking efficiency under different conditions
Finding Braking efficiency under different conditions
With this master cylinder size and our pedal geometry, we would get 100% braking efficiency on all between for all acceptable road conditions with peak coefficients of friction in our range if the brake bias bar is set between 1.25 inches and 1.629 inches.
Master Cylinder Design
Master Cylinder Design
Finding Braking efficiency under different conditions
A hydraulic master cylinder was then created in SolidWorks with the diameter requirements. Parts were modeled after a racing industry push type trunnion cylinder
Cylinder Components
Master Cylinder Design
Cylinder Components
Attachments designed included the master cylinder, the piston arm, brake bar connections and pedal assembly connections. Reservoir containers were not modeled
Pedal and Assembly
Master Cylinder Design
Cylinder Components
A pedal and pedal assembly were also designed to fit within the designated pedal area that met pedal geometry requirements (LP 8.5in, LR 1.6 inches, and distance between the master cylinders is 2.5 inches.)
Finished Design
Finished Design
Finished Design
The final assembly with all pieces mounted moved as anticipated in SolidWorks Motion Study
Results and Deliverables
Results
Through analysis a master cylinder with an internal diameter of .63 inches (16mm) was found the meet the constraints of the project. With this master cylinder we want a pedal that has an 8.5 inch (216mm) moment arm from the application point to the pedal fulcrum (LP) and a 1.6 inch (41mm) moment arm from the fulcrum to the piston of the hydraulic cylinder. This would allow for a 1.2g deceleration with a 40lb pedal force on road conditions with peak coefficients of friction ranging from .3-1.2. For 100% braking efficiency the brake balance bar should be set between 1.25 inches and 1.629 inches. Separation of the master cylinders was 2.5 inches apart.
Deliverables
Designs were delivered for a dual master cylinder and pedal assembly with 2 identical master cylinders, internal hydraulic diameter .633 inches. 2 identical plunger pistons, a brake bias bar, a pedal with LP = 217.14mm and LR = 39.95. Master Cylinder separation was 63.33mm. Additionally mechanical attachments for the cylinders to the assembly, and mechanical attachments from the piston to the brake pedal were designed and delivered. Hardware was designed to incorporate industry size standard attachments including screws and bolts.
What's left Todo?
Future work on this project
While this specific master cylinder was never manufactured, there is further work I would like Todo to continue my learning. I would like to run the model thru a flow simulator and see if I would get the appropriate hydraulic forces.
Additionally, I would like to continue modeling the braking systems to get a deeper understanding of the reservoir system, the hydraulic tubing, rotors and calipers and brake pads. At some point having a full model in SolidWorks motion would be fantastic.
