| Abstract: | Cam/tappet wear is one of the most difficult reliability and durability problems to predict during the development of a prototype engine valve‐train system. In the present study, the cam/tappet surface temperature was measured and calculated to determine the effect of surface temperature on the lubricating conditions at a cam/tappet contact. The measurement method, sometimes called the dynamic thermocouple technique, was based on the Seebeck effect: by using different materials for the cam and tappet, the cam/tappet contact point becomes the hot junction of a ‘thermocouple’. The cam/tappet contact surface temperature can therefore be measured continuously. The measured temperature results show good agreement with predictions. Temperature spikes, however, were not found in the test using new oil, but were shown by the theoretical model. Such results indicate that the cam/tappet interface operates in effective lubricating conditions, even when the oil temperature is relatively high. Further research with degraded oil supplied at high temperature is needed for a thorough understanding of abnormal cam wear. |
