박용 중속 디젤 엔진 밸브트레인의 이상 소음 원인 규명

An abnormal noise was detected in the valve train of newly developed medium speed diesel engine during the shop test. The valve train system and cam profiles were designed based on the kinetic and kinematic analyses. And the vibration characteristics of camshaft were also considered. Nevertheless, the impulse noise was generated and it was confirmed that this is due to the crashing of intake valve in closing timing at the initial test. To investigate the root causes, the dynamic behaviors of valve train system and the torsional vibration of camshaft were measured. From these experiments and the additional analysis, it was concluded that the one of the cause of crashing is coincidence of intake valve closing timing and the fuel cam timing. The other one is the maximum acceleration of intake cam which close to maximum operating speed of valve train. In this work, the intake cam profile was modified to reduce the maximum valve acceleration and then the abnormal noise was disappeared.