Friction Analysis of Connecting Bearing of Piston for Compressor

Abstract

To develop a highly efficient compressor, it is necessary to reduce friction loss of the sliding surfaces. The sliding surfaces of the crank shaft have rotational sliding mode that has good lubricated condition. On the other hand, the sliding surfaces of the piston surface and small end of the connecting rod have bad lubricated condition because these sliding surfaces have reciprocating motion and swing motion. In this study, we evaluated the friction characteristics of the small end of the connecting rod. The structure of small end of the connecting rod are two types,a ball joint type and piston pin type. The result showed that the friction coefficient is independent from the joint structure, the diameter of the piston pin. The friction coefficient is saturated to 0.16 with increasing load. These results mean that the friction loss is proportional to the diameter of the sliding surface. The piston pin with side-relief grooves was evaluated using friction torque test and electrical resistance method. The results showed that side-relief grooves had effect of improving the lubrication condition and making friction torque lower.