基于润滑特性分析的配气凸轮设计

Design of a valve cam based on lubrication characteristics analysis

平底从动件配气凸轮在桃尖附近容易出现润滑危险区,磨损较大,需要进行润滑特性分析。研究表明:配气凸轮桃尖附近润滑系数应满足Nr≥0.5或0.15≤Nr≤0.25,改变凸轮桃尖附近加速度值或凸轮基圆半径,配气凸轮机构获得较好的油膜润滑特性。保证凸轮与从动件之间满足润滑特性要求,能够有效降低配气凸轮机构磨损,当0≤Nr≤0.25或Nr≥0.5,可以增大基圆半径以改善润滑情况;当0.25<Nr≤0.5,应根据凸轮尺寸和接触应力要求增大或减小基圆半径,以满足润滑要求。

The valve cam with the flat follower tends to have poorly lubricated area near the peach tip,which leads to greater wear,so it is necessary to analyze the lubrication characteristics of the cam. The research showed that the lubrication coefficient near the peach tip should meet the formula Nr≥0. 5 or 0. 15≤Nr≤0. 25. Changing the acceleration near the peach tip or the base circle radius could achieve better lubrication,thus reducing wear effectively. When 0 ≤Nr≤0. 25 or Nr≥0. 5,we can increase the base circle radius to improve lubrication. When 0. 15 ≤Nr≤0. 25,we can increase or decrease the base circle radius according to the size of the cam and the contact stress requirements,so as to meet the lubrication requirements.