机油黏度对凸轮挺柱摩擦副润滑性能的影响

Influence of Lubricant Viscosity on the Lubrication of a Cam-Tappet Pair

建立了内燃机配气机构中凸轮挺柱摩擦副的瞬态热弹性流体动力润滑的数学模型,在此基础上着重研究了机油的黏度对凸轮挺柱摩擦副润滑性能的影响。通过计算得到了不同润滑油黏度下摩擦副间的接触区压力场、油膜的温度场、油膜厚度分布和摩擦系数。计算结果表明:在凸轮一个旋转周期内的每个时刻机油黏度越高接触区中心压力越小,润滑油膜的最小厚度越大,但是在不同时刻润滑油的温升和摩擦系数随润滑油的黏度变化并不一致。在卷吸速度为零的55°和125°附近当机油黏度为34.3mPa·s时摩擦系数约为0.34和0.17,但当机油黏度增大到80mPa·s时两个零卷吸速度处的摩擦系数都降低到0.1以下。

The model of transient thermoelastohydrodynamic （TEHL） analysis of a cam-tappet contact in an internal combustion engine was developed. Influence of lubricant viscosity on frictional pair was investigated numerically based on the model. Pressure field, temperature field, oil film thickness and friction coefficient were calculated for different lubricant viscosities. Results show that, in one cycle, the pressure at the contacting center decreases and minimum film thickness increases with increasing lubricant viscosity. However, lubricant temperature increasing and friction coefficient vary with lubricant viscosity differently at different moments. At zero entrainment velocity point of 55°and 125°, friction coefficient is 0.34 and 0.17 under oil viscosity of 34.3 mPa·s, however, the friction coefficient is less than 0.1 at two points of zero entrainment velocity under oil viscosity of 80 mPa · s.