自由活塞发动机活塞环-气缸套的润滑及摩擦特性  

Lubrication and Friction Characteristics of Piston Ring for Free Piston Engine

作　　者：李延骁[1,2] 左正兴 冯慧华[1] Li Yanxiao;Zuo Zhengxing;Feng Huihua(School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China;School of Automotive Engineering, Shandong Jiaotong University, Jinan 250357, China)

机构地区：[1]北京理工大学机械与车辆学院,北京100081 [2]山东交通学院汽车工程学院,山东济南250357

出　　处：《内燃机学报》2018年第4期353-359,共7页Transactions of Csice

基　　金：国家自然科学基金资助项目(51675043)

摘　　要：自由活塞发动机(FPE)工作过程中缸内负载特征、活塞运动规律与曲轴式发动机(CE)不同,为研究FPE活塞环润滑及摩擦特性,利用流体润滑方程与微凸体接触方程建立了FPE活塞环润滑及摩擦模型,并通过试验验证了仿真模型的有效性.通过数值仿真对比了相同结构活塞环在FPE与CE两种工作模式下最小油膜厚度、摩擦力及摩擦功率周期历程,分析了FPE活塞环摩擦学参数对润滑及摩擦性能的影响.结果表明:相对于CE,FPE活塞环在上止点附近最小油膜厚度较大,处于边界润滑状态时间历程较短,摩擦力峰值与摩擦损失较小,但摩擦功率峰值明显高于CE;FPE活塞环桶面高度由2,μm增至4,μm,上止点附近最小油膜厚度降幅为47%,,摩擦力峰值增幅为20%,,摩擦损失降幅为4.6%,;FPE活塞环桶面由-50,μm偏移至50,μm,最小油膜厚度在活塞上行过程减小,下行过程增加,膨胀行程的摩擦力峰值及其作用时间减小,摩擦功率峰值降幅为32%,,摩擦损失降幅为5.2%,.The friction load of the cylinder and the piston for a free piston engine （FPE）is different from a traditional crank engine （CE）. To study the lubrication and friction characteristics of piston ring of the FPE, a numerical model based on hydrodynamic lubrication equations and asperity contacting equations was established. The simulation model was certificated by the experiment of a FPE prototype. Further, the differences of minimum oil film thickness, friction force and friction power loss between the FPE ring and the CE ring were analyzed, and the influences of dif- ferent tribology parameters on lubrication performances for the FPE ring were conducted. Results show that, near the top dead center （TDC）, the minimum oil film thickness of the FPE ring is greater than that of the CE ring and its boundary lubrication duration is shorter. Compared with the CE ring, the peak friction force and the friction loss of the FPE ring are relatively smaller, but its peak friction power is significantly higher. When the tubbish height of the FPE ring increases from 2 μm to 4 μm, the minimum film thickness near the TDC decreases by 47% , the peak fric- tion force increases by 20% and the friction loss decreases by 4.6%. When the tubbish offset of the FPE ring increases from -50 μm to 50 pro, the peak friction force and its duration decrease, the peak friction power decreases by 32% and the friction loss decreases by 5.2%.

关 键 词：自由活塞 活塞环 润滑及摩擦 数值仿真 

分 类 号：TK401[动力工程及工程热物理—动力机械及工程]