供油压力对电液可变气门系统压力波动的影响

Effects of oil pressure on pressure fluctuation of electro liquid variable valve system

液力波动直接影响电液式可变气门系统开闭特性,进而间接影响缸内气体状态参数.基于柴油机电液式可变气门系统工作过程,建立了压力波动系统化评价参数,并通过该评价参数,分析了供油压力(2.5~4.5 MPa)对柴油机可变气门系统压力波动的影响.结果表明:随着供油压力的增加,各压力波动特征值相位(α_1-α_8)均提前,峰值压力p_1,p_2均增加;压力波动区间(β_1,β_2,β_4)的压差、压力突变率均增加,区间β5的压力突变率先增加后减小并趋于平缓;区间β_3的压力波动平均值、波动率及波动方差增大;区间β_6的压力波动平均值几乎不变,波动率变化幅度较小,波动方差值增幅较缓.

Hydraulic fluctuation can directly affect the opening and closing characteristics of electrichydraulic type variable valve system and indirectly affect the status data of cylinder gas. The pressure fluctuation and the systematical evaluation parameters were establised based on the working process of electro-hydraulic variable valve system for DK4 A diesel engine,and the influence of oil pressure from2. 5 to 4. 5 MPa on the pressure fluctuation in variable valve system of diesel engine was analyzed by the evaluation parameters. The results show that with the increasing of oil pressure,the characteristic parameters of pressure fluctuation phases（ α_1-α_8） are appeared in advance,and the peak pressure of p_1 and p_2 are increased. The pressure difference and the pressure mutation rate of pressure fluctuation range（ β_1,β_2,β_4） are increased,and the pressure mutation rate of range β_5 is increased first with latter decreased change. The average value of pressure fluctuation,the fluctuation rate and the fluctuation variance of range β_3 are increased. The average value of pressure fluctuation is almost constant with slight change of fluctuation range,and the variance value is increased slowly in the range of β_6.