变速器行星齿轮机构等强度优化设计

Equal Strength Optimal Design of Planetary Gear Transmission

车辆行星齿轮变速器一般采用经验设计方法得到齿轮参数,使用中部分齿轮会因强度低而导致早期损坏,部分齿轮强度过高而使变速器结构体积增大。由此,提出一种优化方法,以变速器各行星排齿轮强度均等和体积最小为综合优化目标,利用行星齿轮装配条件为约束,求解后得到变速器的齿轮参数,利用ROMAX软件对优化后的齿轮进行仿真分析,得到变速器各行星排最大疲劳应力及疲劳寿命。仿真和试验结果表明:与经验设计方法相比,强化了薄弱齿轮的强度,齿轮接触应力由1 118 MPa降至932 MPa;齿轮的强度更加均衡,齿轮接触应力差值由368 MPa降至193 MPa;齿轮疲劳寿命差距缩小,由15 770.2 h降至9 158.8 h;同时变速箱体积减小8.38%,分析结果与优化目标相符。

Generally, the gear parameters of planetary vehicle transmission are got by the empirical design method. Some gears are damaged early because of low strength, as well as big structure size because of high strength in use. In this paper, the equal strength and minimum volume of the gear box planetary gears were regarded as optimization objective, and the assemble conditions were thought of optimization constraint. The gear parameters were obtained after calculation. Then planetary gears were analyzed by using ROMAX and the maximum of fatigue stress and fatigue life was obtained. The simulation and experiment result shows that some weak strength gears are enhanced and the whole strength is increased. The maximum gear contact stress is reduced from 1 118 MPa to 932 MPa. The stress of all gears is more balanced and the difference of contact stress is decreased from 368 MPa to 193 MPa. The difference of gears figure life is shrunk from 15 770.2 h to 9 158. 8 h compared to the conventional design gear life. The overall volume is reduced by 8.38%. The result is consistent with the optimization target.