三缸发动机整车怠速振动性能研究

Study on Idle Vibration Performance of an Automobile with a Three-cylinder Engine

研究基于传统四缸、横置前驱架构上更换的三缸发动机车辆在怠速工况下车内振动性能。阐述分析未加装平衡轴三缸发动机的激励及整车传递路径特性,并从整车NVH性能集成角度研究降低怠速工况下车内振动措施。研究结果表明:怠速工况下,三缸机一阶不平衡往复惯性力矩引起的怠速振动可以通过发动机的不同激励策略结合整车灵敏度特性及悬置的阻尼特性来消除;而降低1.5阶主燃烧激励引起的怠速振动,除降低发动机负载需求和通过降低悬置X向动刚度获得更低的Pitch模态频率及更高隔振性能外,还可以通过优化响应点处的模态频率来实现。

The idle vibration performance of a vehicle with a three-cylinder engine and without balance shaft was studied. This vehicle was retrofitted by replacing the traditional four-cylinder engine on the transverse frame of the front-wheel driving system by a three-cylinder engine. The excitation source characteristics of the three-cylinder engine without balance shaft module and the vibration transfer path characteristics of the vehicle's body were analyzed. The corresponding measures for improving the vehicle's idle vibration performance were studied from the perspective of vehicle's NVH performance integration level. The results demonstrate that, under the vehicle idle condition, the 1st-order out-of-balance moment response can be eliminated by applying different excitation strategy of the engine according to the vehicle body sensitivity and mount system damping characteristics. Reduction of the 1.5th-order idle vibration induced by the dominant combustion excitation can be realized by the optimization of the model frequencies at the response points in addition to reducing engine idle load demand, acquiring lower pitch mode frequency and better isolation performance by reducing the mount dynamic stiffness in the X-direction.