对于高强化柴油机在标定工况点附近燃烧压力高的问题，可以通过加大进气晚关角实现米勒循环，降低压缩终了时的温度和压力，有效控制燃烧压力，但同时也会造成有效压缩比降低，带来起动困难的问题。采用两段式可变气门技术，可以在启动工况和标定工况下获得理想的工作环境。设计了一种两段式可变气门机构，与传统可变配气技术相比，这种两段式电液可变气门技术通过设计两段式凸轮轴和切换机构，可以控制电磁阀开闭进行气门升程和相位的切换，具有响应迅速、控制精确和工作过程独立的优点。对该机构进行影响规律分析和运动控制的仿真和试验研究，结果表明：油压对切换速度影响较大，油压大于0.12 MPa时可稳定切换，且油压越大，切换响应性越快，而发动机转速对切换几乎没有影响。
For the problem of high combustion pressure near the rated operating point of highly intensified diesel engine, Miller cycle can be realized by increasing the late closing angle of intake air, which can decrease the temperature and pressure at the end of compression and effectively control the combustion pressure, but will also decrease the effective compression ratio and bring about the problem of difficult starting. Using two-stage variable valve technology, ideal working environment can be obtained under both starting and rated conditions. A two-stage variable valve train was hence designed. Compared with the traditional variable valve train technology, the two-stage electro-hydraulic variable valve technology could control the opening and closing of solenoid valve to switch the valve lift and phase by designing the two-stage camshaft and switching mechanism, which had the advantages of rapid response, accurate control and independent working process. The simulation and experiment of motion control and the influence rule analysis were further conducted. The results show that the fuel pressure has a great influence on the switching speed and the fuel pressure beyond 0.12 MPa will make the switching process stable. And the greater the fuel pressure, the faster the switching response. Besides, engine speed has little effect on switching.
