Braghin, F. and Salis, F., "A Low Cost System for Active Gear Shift and Clutch Control," SAE Technical Paper 2015-01-0228, 2015, doi:10.4271/2015-01-0228.
The objective of this study is to demonstrate the design and construction of an innovative active gear-shift and clutch for racecars, applied to a Formula Student car, based on the use of DC gear-motors. Racecars require extremely quick gear-shifts and every system to be as light as possible. The proposed solution is designed to reduce energy consumption, weight and improve gear-shift precision compared to traditionally employed electro-hydraulic solutions, although maintaining state of the art performances. The proposed gear motor actuation satisfies all the above objectives: energy can be saved by removing the need for power when clutch is not pulled, thus improving efficiency; by substituting the entire electro-hydraulic-systems, that accounts for approx. 5% of the overall car weight (10kg); a significant weight reduction is achieved (weight is reduced to 2kg); a fine actuation force modulation, in order to properly shift to neutral, can easily obtained with an DC electric motor; and, above all, shifting time is less than 20ms. System modeling, regulator design, based on PI-control, and simulation were carried out. Electronics, both signal and power, micro-controller based design and program coding, written in C language, were the next steps. Finally, accurate tests to validate the solution and assess performances were carried out.