某皮卡车型离合器踏板抖动问题研究

某皮卡车型在起步松开离合器踏板时,踏板存在明显的抖动,甚至发麻感觉,使驾驶员产生一定的抱怨。文章参考离合器踏板抖动的产生机理和关键问题影响因子,增加相应的控制措施和优化路径。该优化路径经过主观评价和客观测试充分验证后,对离合器踏板抖动问题改善明显,提升了离合器踏板操纵舒适性。     

Experimental Analysis and Optimization of Timing Belt Guide Plate Material on Engine Operational Friction Loss

We focus on the friction loss measurement and reduction of the timing belt guide plates of a fourcylinder gasoline engine. To minimize the friction loss caused by the dynamic friction of the guide plates during timing belt motion and improve the efficiency of the internal combustion engine(ICE), we adopt four different plastic materials in fabricating the guide plates. With controlled engine boundary conditions and operational modes, an AVL electric dynamometer is used to measure the output of the engine. The results indicate that selecting polytetrafluoroethylene(PTFE) as the additive in fabricating the guide plates can effectively reduce the friction loss, so that the output torque and output power of the engine can be improved, thus reducing fuel consumptions. This work also has positive impact on the efficiency optimization of similar ICEs.     

直喷发动机燃油喷雾特性经验公式定量研究

基于对节能减排的需求,直喷发动机喷雾特性受到研究人员广泛关注.大量试验与数值仿真方法被应用于对直喷喷雾特性的测量与预测中.其中,基于试验的研究以获取描述喷雾特性的经验公式为目的展开.此类研究可获得大量数据,而从中提炼的经验公式对于实际喷雾系统的优化具有指导意义.然而经验公式法本身存在较大局限性,多数经验公式只适用于特定或若干工况,且其假设的先决条件往往不完全符合实际燃油雾化环境.此外,不同经验公式获取的结果由于其参数选取、试验条件不同,彼此间存在一定的差异.因此,如何评价喷雾特性经验公式的普适性是领域内亟需解决的问题.本研究以独立试验为基准,定量比较了现有文献中主流经验公式的预测结果,并根据特定工况预测结果偏差对各经验公式的局限性进行了阐述,对于下一代汽油机设计与燃油雾化系统优化具有一定的指导价值.