【摘要】 设计开发了一种无凸轮电液可变气门机构(EHVVA)，建立了该可变气门机构动态特性试验平台，通过试验探索了EHVVA在4种发动机转速(2 500、2 000、1 500和1 000 r/min)下的动态运行特性．与凸轮驱动气门机构不同，EHVVA运行特性受发动机转速影响较小，丰满系数高于传统凸轮驱动气门机构；高速工况下EHVVA加速度峰值低因而具有更小的往复惯性力．EHVVA的柱塞腔内油压在单循环内的变化可分为油压建立阶段、油压保持阶段和油压卸荷阶段．随着发动机转速的提高，需提高驱动油压以实现气门快速开启，同时随着信号脉宽变短，气门运动逐渐由充分响应转换为非充分响应状态．探索了EHVVA的循环变动特性，结果表明：柱塞腔最大油压、最大升程及时面值的循环变动率均小于4%.更多还原

【Abstract】 A camless electric-hydraulic variable valve actuator(EHVVA) test system was designed and developed.Operating characteristics of the EHVVA were investigated experimentally under four different engine speeds of 2 500,2 000,1 500 and 1 000 r/min,respectively. Unlike the cam derived valve mechanism,the EHVVA characteristic is less influenced by the engine speed while possesses relatively higher fullness coefficient. Moreover,the peak acceleration for the EHVVA is lower than that for the cam derived cases under high engine speed conditions,indicating a smaller reciprocating force of inertia. Evolution of oil pressure within the plunger cavity can be divided into three distinct stages,i.e.,the oil pressure set up stage,the oil pressure hold stage and the oil pressure unload stage. As the engine speed increases,increasingly higher driven oil pressure is needed to achieve better valve opening responsiveness. In the meantime,the reduced control signal pulse width finally results in the operating condition transition from full response state transform into insufficient response state. The research result of the cycle-tocycle variation characteristics show that the variation coefficients for the maximum oil pressure,the maximum valve lift and the time-area value of the valve opening are all less than 4%.更多还原