张士强，李春书，戴俊，刘瑞林，张卫国.汽油机可变进气门相异升程机构研究[J].内燃机工程,2019,40(3):46-55.
汽油机可变进气门相异升程机构研究
Research on Variable Dissimilitude Lifts Mechanism of Intake Valves of a Gasoline Engine
DOI：10.13949/j.cnki.nrjgc.2019.03.007
关键词:4气门汽油机  可变气门相异升程  相异角  凸轮轴
Key Words:four-valve gasoline engine  variable dissimilitude lift of valves  dissimilitude angle  camshaft
基金项目:国家自然科学基金项目（51246010）；河北省高层次人才资助项目（A201803023）；河北省高等学校科学技术研究项目（Z2018028）
作者单位
张士强，李春书，戴俊，刘瑞林，张卫国 1.河北工业大学 机械工程学院，天津 300130； 2.唐山学院 交通与车辆工程系，唐山 063000； 3.军事交通学院 汽车工程系，天津 300161 
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摘要:提出了汽油机可变进气门相异升程机构方案，通过调整进气凸轮相异角改变两个进气门升程差产生涡流和调整涡流。计算表明当齿轮螺旋角增大、分度圆半径减小时，相异角增大；存在相异角时，两进气凸轮转角不同，转矩与液压平衡力也不同，进气持续期随相异角增大而增加。有限元分析结果显示该机构凸轮轴安全系数为2.04，最大等效应变为6.73×10-4 mm，强度及刚度均符合要求，且不会发生共振。缸内稳流试验证实进气门相异升程能够产生大尺度涡流，并且进气流量几乎不变。当相异角为8°时涡流强度可达0.24，平均流量系数偏差仅为0.93%，滚流随相异角增加略有增强。相异升程汽油机性能试验表明适当的相异角会使中低速转矩提高2.94%,高速功率提高3.03%。
Abstract:A mechanism scheme of the variable dissimilitude lifts(VDL) of intake valves was proposed, calculated and analyzed with the finite element analysis(FEA) for a four valve gasoline engine, which could produce and regulate in-cylinder swirl by adjusting the dissimilitude angle between two intake cams to change the difference between the lifts of two intake valves. The calculation results showed that the dissimilitude angle increased when the gear helix angle increased or/and the standard pitch circle radius decreased; the turning angles, turning torques and hydraulic balancing forces of the two intake cams were different when there was a dissimilitude angle, and the intake duration was getting longer with the increase of the dissimilitude angle. The FEA results show that the safety coefficient of the camshaft is 2.04, the maximum equivalent strain is 6.73×10-4 mm, the strength and stiffness conform to the requirements, and the resonance will not occur. A test of steady flow in cylinder confirms that VDL can obtain a large scale swirl and the intake flow almost remain constant; the swirl intensity can reach 0.24 when the dissimilitude angle is 8°, the deviation of the average flow coefficient is only 0.93%, and the tumble intensity slightly increases with the increase of the dissimilitude angle. The results of performance tests of the gasoline engine with VDL show that an appropriate dissimilitude angle can make the torque at middle low speeds increase by 2.94% and the power at high speeds by 3.03%.
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