基于米勒循环要求的高速船用柴油机凸轮型线设计研究

The Cam Profile Design of High Speed Marine Diesel Engine Based on Miller Cycle

采用非对称(高次方-分段函数)设计方法对某高速船用柴油机凸轮型线进行了优化设计,基于多体动力学模型对其动力学性能进行了校核,并基于单因素扰动法对影响米勒循环实现的配气机构关键参数进行了敏感度分析。研究结果表明:优化后的凸轮型线不仅满足使用米勒循环技术的设计要求,还提升了阀系动力学性能,且使得落座力峰值下降了42.9%,最大接触应力下降了13.8%。适当减小米勒正时和气门升程,增加阀系刚度和弹簧刚度均有利于实现米勒循环的凸轮型线设计,其中阀系动力学性能对米勒正时最为敏感,在确定米勒时刻时应综合考虑整机结构强度和性能要求。

An asymmetric design method （POLYDYNE-ISAC） was used to achieve the optimization design of the cam profile for a high speed marine diesel engine. The dynamic performance was checked by a multi-body dynamics model using AVL EXCITE Timing drive, and the sensitivity analysis of the key factor affecting the valve train of the miller cycle was studied by a single parameter perturbation method. The research results show that the optimal cam profile can not only meet the requirements of the Miller cycle but also improve the dynamic performance of the valve system. So that the seat force and contact stress can be decrease by 42.9% and 13.8% respectively. It is proved that the Miller cycle can be implemented by decreasing the Miller timing and the valve lift, or increasing the rigidity of the valve train system and the springs, among which the dynamic performance valve train system was extremely sensitive to Miller timing. The results show that the performance requirements and the structural strength of the engine should be taken into consideration when considering the Miller timing.