基于气门升程曲线的发动机性能优化

进排气门的开启时刻,对气缸充量有重要的影响。利用进气惯性及进气门迟闭可以有效地增加气缸充量,而较大的迟闭角可能会因为活塞的上移将气体推出气缸,减小气缸充量。同样,排气提前可以有效地降低缸内残余废气,使排气通畅;而较大的排气提前角可能会造成有效功的损失,并导致各缸间进排气干涉,减小气缸充量。采用仿真分析的方法,分析造成发动机扭矩偏低的原因,更改进排气门升程曲线,有效地增加气缸充量,增加发动机动力性。同时通过试验验证,选用最终的实施方案。

Engine Performance Optimization through Valve Profile Modification

Cylinder charge is greatly affected by the intake and exhaust valve opening and closing time. Because of flow inertia,the charge can be increased with a delayed intake valve-closing,while an overdelayed closing time may lead to the reduction of the charge,which is pushed by the up-moving piston. Meanwhile,an advanced opening of exhaust valves reduces the residual gas in the cylinder and smoothes the exhaust flow. If the advancement is too large,it may result in the damage of the effective power and the reduction of the in-cylinder charge because of the interference of intake and exhaust flow of each cylinder. In this article,the cause of low engine torque was analyzed by simulation method. The valve lift curve was modified to efficiently increase the cylinder charge and improve the engine power. The final implementation plan was determined through experimental validation.