Reduction of Friction between Cam and Follower by Engine Oil and Surface Coating

Abstract

The influence of the engine oil property and the cam follower surface coating on the friction characteristics was examined with a cam follower friction test apparatus. It was found that the friction changes with the contact load, the camshaft rotation speed and the lubricant temperature such as the contact condition is governed under the mixed lubrication regime. It also changes markedly with both the property of low SAPS engine oil to protect the exhaust gas after-treatment device for diesel engines and the surface coating condition of the follower surface. The followings were made obvious. (1) The friction changes under the running-in with the frequency of test. (2) The friction is influenced by the combination of the follower surface treatment and the low-SAPS engine oil. (3) The effect of it on the reduction of friction becomes the largest when the DLC coating and the DH-2 class oil are combined.