修形人字齿轮的润滑及摩擦特性分析

Analysis of Lubrication and Friction Characteristics for Modified Herringbone Gear

基于热弹流润滑(TEHL)理论对修形人字齿轮的齿面润滑特性和摩擦特性展开分析。首先,分析在指定工况下特定结构的人字齿轮齿面的时变接触线变化规律,沿啮合线选取指定数量的啮合点作为分析对象并得到必要的接触参数数值;然后,对TEHL计算程序的准确性进行验证并完成TEHL计算,从计算结果中提取不同啮合点处油膜特征参数,以得到其在啮合线上的变化规律,并以啮合点S1为例分析了输入扭矩、主动轮转速和鼓形修形量对油膜轮廓曲线的影响;最后,利用Ree-Eyring模型求得齿面啮合点的摩擦系数变化规律。计算结果表明:最大油膜压力在齿面上呈现先增后减的变化趋势,最小油膜厚度和最高油膜温升的变化趋势与其相反;主动轮转速对油膜温升和厚度有显著的影响;输入扭矩或修形量的增加均会导致油膜压力、温升曲线峰值的上升;摩擦系数在齿面节点几近于0,而在啮入侧、啮出侧的数值较大。

Based on the theory of thermal elastohydrodynamic lubrication(TEHL),the lubrication and friction characteristics of modified herringbone gears were analyzed.Firstly,the variation of instantaneous contact lines on tooth surface of the herringbone gears with the specified structure was analyzed under the specified working condition.The specified number of meshing points along the meshing line were selected as analysis objects and the essential values of contact parameters were obtained.Secondly,the accuracy of the TEHL calculation program was verified and the TEHL calculation was performed.The oil film characteristic values at the meshing points were derived from calculation results to obtain their variations along the meshing line.The influences of input torque,driving gear rotation speed and amount of crowned modification on the film profile curves at the meshing point S1 were analyzed.Finally,the variation law of the friction coefficients at the meshing points was obtained by using the Ree-Eyring model.The calculation results show that the maximum film pressure on tooth surface increases first and then decreases,while the variation trends of the minimum film thickness and the maximum film temperature are opposite to that of the maximum film pressure.In addition,the temperature rise and the thickness of the film are influenced significantly by the rotation speed of driving gear;the increase of input torque or amount of crowned modification will lead to the film temperature rise and the peak value rise of the film pressure;the value of friction coefficient is almost zero at the pitch point while greater at the engaging-in/out side.