Abstract
To join in the students racing car development program that is organized by the Society of Automotive Engineers, students at the Kanagawa Institute of Technology developed a formula-type racing vehicle with space-frame body structure. The vehicle is powered by in-line four-cylinder gasoline engine that is used as a load-carrying member of the frame. This design can cut much weight, but tends to invite heavy vibration because no resilient vibration insulator can be placed between the engine and the frame. To overcome this trade-off problem, structural dynamics modification technique was applied through FEM and experimental modal analyses. By this technique, very light structure was developed with such design features as aluminum alloy panels fixed to the frames and corner ribs. To suppress remaining noise and vibration by crankshaft second-order harmonics, and active dynamic damper system was installed. Using liquid filled cavity as a leverage mechanism, the dynamic damper was able to produce large counter force with relatively small electric current. In addition, the damper was controlled by adaptive feed-forward control scheme using engine tacho-pulse as the reference signal. By this arrangement, the active dynamic damper could track the second order harmonic. Though the active dynamic damper cannot control all the modes, this study demonstrated the potential of active dynamic damper when vibration insulator performance is limited.
