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A New Variable Valve Mechanism-Shuttle Cam
Published April 08, 1992 by Associazione Tecnica Dell'Automobile in Italy
Event: 3rd International Conference Innovation and Reliability in Automotive Design and Testing (1992)
In the view of preserving the environment, a reduction of exhaust emissions and improving the fuel consumption in automotive engines are becoming more urgent, however the driveability should not be affected. Although small displacement high revolution engines are considered to be one of the suitable, their poor torque in lower revolution affects driveability. In order to improve the torque of these high revolution engines, variable valve mechanisms have been put into practical use, however, they have not achieved their goals sufficiently.
A camholder moving variable valve mechanism was currently studied. It was applied to a 250 cc single-cylinder motorcycle engine and resulted in a 20% torque increase and a 13% improvement of BSFC at 50 km/h constant speed. The camholder is driven by a small electric motor and the mechanism worked accurately in the high speed ranges up to 10,000 rpm. Moreover, the possibilities of its application to multi-cylinder engines were suggested.