Abstract
Engines for two wheels vehicles with automatic transmission which are used at higher and higher speed are subject to dynamic phenomena that are becoming very important. Every function may be responsible for its noise and reliability, but it could also transfer some frequencies to other functions that may grow and be liable for unpredictable consequences. These problems are present in the valve gear system. In fact some frequencies may rise and affect the noise due to the impact of all the mechanism- members. Moreover they may transmit vibrations that could excite both other components (supports, covers and so on) and the engine transmission. So its absolutely necessary to perform an experimental analysis about these problems that considerably affect comfort, functionality and reliability.
PIAGGIO has built a test bench to carry out the experimental analysis of whatever kind of distribution system, equipped with the following tools: laser sensor for valve shifting, strain gauges for forces, accelerometers to determine the right moment of valve closing. Moreover typical frequencies can be identified. All the signals are recorded, analysed in the frequency domain, compared with theoretical data in real-time, using one computing environment. A team, that is able to analyse all the problems in simultaneous engineering from the design to the testing, carries this out.