Spring 2019 Senior Design: Baja SAE

 

baja cvt

 

Students: Matthew Lane, Hannah Pollek, Ben Marson, Gavin Broughton

Our Senior Design Project is to redesign and fabricate the primary unit of the Continuously Variable Transmission (CVT) for the Baja SAE Car. The belt-driven CVT replaces a conventional gear transmission by using centripetal force to continuously change the “gear ratio” between the primary and secondary units. This allows the car to receive high torque from the engine when accelerating from rest, then automatically transition to high speed when the engine reaches max rpm. Redesigning the primary on the car will allow us to optimize when and how this gear shift occurs and provide maximum power output from the motor to the system at all times, improving the overall performance of the car.

In the Fall, our team developed a number of mathematical models based on the forces seen within the system in order to drive the new designs. A series of 3D printed ramps (ramps heavily affect the shift profile and performance of the unit) were run in the old system to validate our mathematical hypotheses. We also tested the old system’s top speed and acceleration times to provide a benchmark for our new system. The new design interfaces with the old secondary with goals to improve the car’s top speed by 1 mph while maintaining the same acceleration times as the old system, as well as lower the temperature the system sees by 10%. We are now nearing completion of manufacturing and assembly and are preparing multiple computerized test rigs to test acceleration, top speed, and temperature data of the complete system.