基于凸轮机构驱动的无级变速器设计与仿真

Design and Simulation of Continuously Variable Transmission Driven Based on Cam Mechanism

针对现有无级变速器变速范围窄、最大传动比小的问题,提出了一种基于凸轮机构驱动的无级变速器.该无级变速器通过变速装置调整中间摆臂支点位置,改变力臂,从而调节从动件的旋转速度,实现无级变速目的.根据摇臂输出端转速的变化规律,控制摆臂转速按一定规律变化,对输出速度进行反向补偿,提高了运动输出的平稳性.利用反转法原理,分别对凸轮轮廓曲线、摆臂轮廓曲线进行设计,并将凸轮组中4组凸轮均匀错开22.5°,保证无级变速器在运行的过程中,至少有一组凸轮处于推程状态,实现运动连续输出.利用NX10软件对传动机构进行运动学仿真,通过分析不同传动比状态下摇臂的角位移曲线图,验证了无级变速器总传动比在一定调速角范围内,可实现运动连续平稳输出.本文无级变速器可获得较宽的变速范围和较大的传动比,弥补了现有无级变速器变速范围窄、最大传动比小的不足.

In view of the narrow range and small maximum transmission ratio of the existing Continuously Variable Transmission(CVT),this paper proposes a CVT driven by cam mechanism.The CVT adjusts the position of the intermediate lever fulcrum by the shifting device and changes the force arm to adjust the rotational speed of the follower and achieve the aim of stepless shifting.According to the change rule of the speed in the output end of the rocker arm,the speed of the swing arm is controlled to change according to a certain rule,and the output speed is compensated reversely,which improves the stability of the motion output.With the principle of inversion method,the cam contour curve and the swing arm contour curve are designed,separately,and the four groups of cams in the cam group are evenly staggered by 22.5°to ensure that at least one set of cams is in an effective push state during the operation of the mechanism to keep continuous motion output.The NX10 software is used to simulate the kinematics of the transmission mechanism.By analyzing the speed-time curve of the rocker arm under different gear ratios,the continuous and outputsmooth transmission output can be realized when the total transmission ratio of the CVT is within a certain speed control angle.The CVT can obtain a wide range of transmission and a large transmission ratio,which makes up for the shortcomings of the existing CVT,such as narrow range of transmission and small maximum transmission ratio.