柴油机电动可变气门正时机构特性

Low compression ratio Miller cycle in highly-intensified diesel engine can effectively control the burst pressure. The increase in the late intake valve closing (LIVC) timing brings reduction in the effective compression ratio, which leads to difficulty in starting.The application of variable valve timing technology can effectively take into account the relationship between the burst pressure and the starting of diesel engine. A simulation experimental device of electric variable valve timing mechanism was designed. The electric variable valve timing mechanism is composed of brushless DC motor, NN small tooth number difference deceleration mechanism and related control system. It can achieve high response phase adjustment with an adjustment accuracy of ±0.116°. According to the characteristics of the mechanism, a mathematical model of the system is established, the characteristics of the motor are checked, the basic adjustment characteristics are analyzed, and the initial PID parameters are optimized. A bench test study was carried out to verify the basic timing adjustment characteristics, starting adjustment characteristics, and voltage influence characteristics. The research results show that the electric variable valve timing mechanism can achieve basic timing angle adjustment, the maximum late closing angle can be reached within 5s under starting condition and the reduction in battery voltage has an effect on the advance in phase angle, but does not affect the delay of phase angle.