An investigation on the effects of camshaft surface defects on producing high-frequency noises in internal combustion engines

Valvetrain is one of the major sources of noise and vibration in IC engines. The importance of cam surface quality parameters is highlighted in the valve train mechanisms with direct sliding contact between cam and tappet. In this paper, the influence of surface quality parameters on high frequency noise producing is investigated. The roughness and waviness of some intake and exhaust camshafts with diverse surface qualities were measured and then were mounted on a four cylinder gasoline engine to measure the noise level of valvetrain mechanism through NVH analysis. Furthermore, the characteristics of the unusual sound which is considered as an annoying noise were determined also, the camshaft Surface topology was inspected by a Scanning electron microscope (SEM). The results show that the nonconformities in surface parameters such as roughness and waviness are the main factors that lead to producing high frequency annoying noise and therefore must be carefully considered by designer.