Research On Development Of A LPG Four Stroke SI Engine For Motorcycle

Research on alternative transportation fuels is one of the most important research projects in the 21th century, focusing on dealing with more and more serious and pressing problems of environmental conservation and energy saving of the globe. Now, development of alternative fuel motorcycle is challenging whole motorcycle industry in China to face the demand of durable development of the motorcycle industry. So development of an original LPG motorcycle is put forward in the thesis to try to obtain more harmonic correlation between the development of the industry and the environment conservation of the globe.Some research results are achieved as follows:(1) Layout of LPG supply system and modification of body construction are carried out, and structural analyses of fuel supply bracket are performed. Then fuel bottle with single-welding line and valve type specially used for LPG motorcycle is designed and fabricated, and boil-off pressure adjuster and mixing unit of LPG fuel supply are successfully developed.(2) LPG engine performance due to various factors such as different type mixing unit, structural parameter of engine, ignition unit, A/F, as well as combustion characteristic et al. are experimentally investigated into. Long-hole and geometrical proportion type of mixing unit is finally adapted in LPG supply system, and power and torque output of LPG engine are improved by increasing compression ratio, and ignition characteristic is tried to adjusted to satisfy engine performance. Meantime emission performance and noise level of LPG engine at full-throttle and other various part-throttle operations are tested and compared with former gasoline engine.(3) It is verified by engine dyno tests that LPG engine has better synthesized performance at aspects of power and torque, fuel economy, as well as emission than former gasoline engine. Furthermore, it is also verified by chassis dyno tests that LPG motorcycle has better emission performance than gasoline engine, and has better acceleration performance e.g. exceed acceleration than former gasoline engine, and has low noise level characteristics as well as has ability to achieve equivalent level fuel economy performance compared with former gasoline engine.