柴油机电动可变气门正时机构特性

高强化柴油机通过实现米勒循环可有效控制爆发压力，进气门晚关角的加大导致有效压缩比的进一步降低，带来启动困难的技术问题，采用可变气门相位技术可有效兼顾爆发压力与柴油机启动的关系。研究设计一种全新的电动可变气门相位控制机构模拟试验装置,该装置由无刷直流电机、少齿差型减速机构及相关的测控系统组成，可实现高响应的相位调节，调节精度为±0.116°. 依 据机构的特征建立系统的数学模型，对电机特性进行试验校核，分析基本调节特性，优选控制初始PID参数。开展模拟台架试验研究，验证正时基本调节特性、启动调节特性及电压影响特性。结果表明：所设计的电动可变气门正时机构可实现基本的正时角度调节，兼顾米勒循环配气相位与启动工况配气相位；启动工况下5 s即可到达最大晚关角；模拟试验条件下，蓄电池电压降低对相位角提前有较大影响，但并不影响相位角延后。

Characteristics of Electric Variable Valve Timing Mechanism of Diesel Engine

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.