Abstract:

To reduce the impact of engine vibration during start process on the vehicle ride comfort, which is important in particular when the startstop control strategy is applied in the engine, the vibration signals of the first cycle during start of engine were measured, and the effects of the initial position of piston, the cooling liquid temperature and the cranking speed on starting vibration were investigated on a Jetta 1.6 L gasoline engine. The results show that when the piston stays initially at the position near the top dead center after the intake valve closing, engine starting vibration is relatively weak. The vibration at warm starting(corresponding cooling liquid temperature 85 ℃)is weaker than that at cold starting(20 ℃).The cranking speed makes a notable impact on the starting vibration of the engine, rapid cranking makes much weaker vibration than original basic engine slow cranking does.

Key words: power machinery and engineering, gasoline engine, vibration, start process