全可变液压气门机构的气门运动特性

摘要

通过对全可变液压气门机构的气门升程和液压压力的试验测量,研究了全可变液压气门机构的气门运动特性.采用流通面积随气门升程可变的节流孔控制气门落座速度,分析了节流孔形状、最小节流面积和节流面积变化率等对气门落座过程的影响;采用单向阀通道降低液压系统内的液压流体的压力波动,保证了气门的平稳开启.通过对多种工况下气门落座速度的分析,得出气门最大升程对气门落座速度有重要影响,而发动机转速对气门落座速度的影响相对较小的结论.试验结果表明,通过合理匹配有关结构参数,全可变液压气门机构可实现气门平稳开启和平稳落座.%The characteristics of valve movement using fully variable hydraulic valve train is studied by measurement of valve lift and oil pressure of fully variable hydraulic valve train.Valve-seating velocity is controlled by a variable throttle hole whose flow area is changed with valve lift.The effect of the shape,the minimal flow area and the flow area changing rate of throttle hole on valve seating process is analyzed.Pressure fluctuation of the hydraulic system is reduced by one-way valve to protect the valve steadily opening.Analysis on valve-seating velocity under different conditions shows that the effect of maximum valve lift on valve-seating velocity is significant, while the effect of engine speed is relatively small.Testing results also show that by reasonably matching the structural parameters, the fully variable hydraulic valve train can give steadily opening and seating.