配气机构动力学计算在WD618机型上的应用

在WD618 44性能试验后的拆检过程中,发现活塞顶部排气门侧有裂痕,且凸轮轴磨损严重。针对上述情况,对原机配气机构进行了动力学计算,计算结果表明,进排气门都存在飞脱现象,由于在进气凸轮飞脱区域内气门和活塞相距较远,不会造成碰活塞现象,而排气门飞脱及活塞热膨胀会造成排气门碰活塞,因此,配合活塞顶部避碰坑加深又重新设计了一条高次方动力排气凸轮,新排气凸轮能有效减小飞脱量及降低凸轮接触应力,性能试验表明,装配新凸轮轴的机器性能比原机没有降低且没有发现活塞顶部有裂痕出现。

Application of the Dynamic Calculation for Valve Train in WD618 Diesel

The crack is generated on the side of exhaust valve for piston and the cam is badly worn after the performance test of WD618 44 is over.So the dynamic calculation for valve train of original diesel is made.The calculation result shows that both inlet valve and exhaust valve are separate.The inlet valve,far away from piston when it is separate,does not collide with piston.But the exhaust valve does collide with piston greatly because of the separation of valve and thermal expansion of piston.A new high power exhaust cam profile is designed and the tunnel for avoiding collision is deepen.The separation and contact stress of new exhaust cam profile are reduced.The test shows that the performance of engines with new cam shaft is not worse than that of the original engines,and the crack of piston is not found.