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通过可变气门机构使部分燃烧废气保留在缸内,是实现汽油机可控自燃(controlled auto-ignition,CAI)燃烧的切实可行的办法,然而多参数可调气门机构增加了控制的复杂程度.为此,利用一维循环模拟软件在Simulink环境中建立了带有进、排气门升程及定时均可控的四变量气门执行机构(4-variable valve actuating system,4VVAS)的汽油机仿真试验平台,探讨了气门各参数对循环热废气及CAI燃烧过程的控制作用及控制敏感性.研究结果表明,其他参数相同时,排气门定时对汽油机CAI燃烧的影响主要体现在缸内废气残留量及废气温度的大小,而进气门定时主要通过影响进气回流和有效压缩比来影响燃烧过程;存在一个最佳位置没有进气回流,能够取得最大负荷.在当量比燃烧时,排气门参数对发动机负荷和着火时刻的控制最为直接和有效,是汽油机CAI燃烧的重要控制参数.
Controllable auto-ignition (CAI) combustion of gasoline engines is a feasible solution to keep some of the combustion exhaust gas in the cylinder through the variable valve mechanism, however, the multi-parameter adjustable valve mechanism increases the control complexity. In this paper, a simulation test platform for gasoline engine with four-variable valve actuating system (4VVAS) with both inlet and exhaust valve lift and timing controllable is established in Simulink environment by using one-dimensional cycle simulation software. The control effect and control sensitivity of each parameter of the valve on hot exhaust gas and CAI combustion process are discussed.The results show that the influence of exhaust valve timing on the combustion of gasoline engine CAI is the same when the other parameters are the same, Temperature, the intake valve timing affects the combustion process mainly by affecting the intake backflow and effective compression ratio; there is an optimum position without intake backflow, which can achieve the maximum load. In the equivalence ratio combustion, the exhaust valve parameters The control of engine load and ignition time is the most direct and effective, and it is an important control parameter of gasoline engine CAI combustion.