A Study of Heat-Transfer through the Piston-Ring of Diesel Engine

Abstract

Using the temperatures of piston, ring and liner measured by means of thermocouples, some heat resistances between the ring-land and the ring R_p, the ring itself R_r, and between the ring and the cylinder-liner R_l were calculated and examined separately. As a result, the following facts were found. (1) R_p in the running condition is nearly equal to that value, which has been reported, as the contact resistance, when the metals are brought into static contact with each other. (2) R_p is hardly affected by the kind of piston metals and also the engine load. (3) R_l depends mainly upon the thickness of oil film formed on the ring surface. As the ring temperature rises with the increase of engine load, the film becomes thin and then R_l decreases. (4) Since the values of R_r and R_l are very smaller than that of R_p, the total heat resistance in such a heat transmisson process seems to be almost governed by R_p only.