RV减速器摆线针轮传动脂润滑弹流分析

Elastohydrodynamic Analysis of Grease Lubrication for Cycloid Pin Wheel Transmission of RV Reducer

根据RV减速器摆线针轮的几何学和运动学理论,分析了摆线针轮传动在不同啮合位置的当量曲率半径、卷吸速度和单位长度载荷的变化规律;基于润滑脂的Ostwald模型建立线接触脂润滑弹流分析模型,分析了载荷、卷吸速度以及流变指数对脂膜厚和压力分布的影响;并对摆线针轮在不同啮合位置进行脂润滑数值分析,获得了啮合离散点的脂膜形状和压力分布,进而通过计算膜厚比得出针齿从摆线轮齿根到齿顶啮合过程中的瞬时润滑状态,确定了摆线轮的润滑不良区域。结果表明:脂润滑的膜厚、压力分布特征及其随载荷和卷吸速度的变化规律与油润滑的特征规律相似,但从定量角度看,相同条件下油润滑的膜厚要高于脂润滑膜厚;在RV减速器摆线针轮传动中,随着针齿从齿根到齿顶的啮合,当量曲率半径快速降低后变化缓慢,卷吸速度先降低后缓慢增大,单位长度载荷快速增大后缓慢降低;当量曲率半径、卷吸速度和单位长度载荷的变化也使得不同啮合点的润滑性能随之变化,针齿在摆线轮齿根部位啮合时脂膜厚较大,从摆线轮齿根到齿顶润滑性能逐渐由好变差,摆线轮齿顶部位为润滑不良区域;润滑脂膜厚随着流变指数的增大而增大,通过增大润滑脂的流变指数,可以有效改善摆线针轮传动的润滑状态,提高摆线轮的寿命。

According to the geometry and kinematics theory of the cycloid pin wheel of the RV reducer,the equivalent radius of curvature,entrainment speed and load per unit length of the cycloid pin wheel transmission at different meshing positions were analyzed.Based on the Ostwald model of grease,a linear contact grease lubrication elastohydrodynamic analysis model was established,and the influence of load,entrainment speed and rheological index on the grease film thickness and pressure distribution was analyzed.Numerical analysis of grease lubrication at different meshing positions of the cycloidal pinwheel was carried out,and the shape and pressure distribution of the grease film at the discrete points of meshing are obtained,and then the instantaneous lubrication state of the needle teeth during the meshing process from the root of the cycloidal gear to the tooth tip was obtained by calculating the film thickness ratio,and the poor lubrication area of the cycloidal gear was determined.The results showed that the film thickness and pressure distribution characteristics of grease lubrication and their changes with load and entrainment speed were similar to those of oil lubrication,but from a quantitative point of view,the film thickness of oil lubrication was higher than that of oil lubrication in the same conditions.In the RV reducer cycloid pin wheel drive,as the pin teeth mesh from the tooth root to the tooth tip,the equivalent radius of curvature decreased rapidly and then changed slowly.The entrainment speed first decreases and then slowly increased,and the load per unit length increased rapidly and then slowly decreased.The change in equivalent radius of curvature,entrainment speed and load per unit length also changed the lubrication performance of different meshing points.When the needle teeth mesh at the root of the cycloidal gear,the thickness of the grease film was larger.The lubrication performance from the root of the cycloidal gear to the top of the tooth gradually changed from good to worse,and the top of the cycloidal gear was a poorly lubricated area.The thickness of the grease film increased with the increase of the rheological index.By increasing the rheological index of the grease,the lubrication state of the cycloidal pin wheel transmission could be effectively improved,and the life of the cycloidal wheel could be improved.