Research On CVT Based On Cam Drive

As the core part of mechanical transmission,CVT is widely used in mechanical products.The existing mechanical CVT mostly adopts V belt transmission,and its working principle is to change the output speed by adjusting the transmission radius of the driving wheel and the driven wheel.Due to the limitation of the transmission radius and V belt structure,its maximum transmission ratio is limited,and there are still some shortcomings in the specific application field of wide speed range and large transmission ratio.In this paper,a kind of CVT driven by cam is proposed.Based on the principle of lever,the CVT can adjust the position of lever fulcrum through the speed regulating mechanism,so as to adjust the output speed of the follower,so as to obtain a wide range of speed change and a large transmission ratio.The specific research contents are as follows:(1)A kind of CVT Based on cam drive is proposed.The CVT consists of an input shaft with driving cam,a swing arm whose fulcrum is located on the speed governing plate,and a swing arm whose fulcrum is installed on the output shaft through a one-way clutch.The fulcrum position of the middle swing arm is adjusted by the speed change device,and the force arm is changed,so as to adjust the output speed of the follower and realize the purpose of CVT.Based on the kinematic principle,the kinematic model and the total instantaneous transmission ratio equation of CVT are established.The mechanism can realize CVT and the maximum transmission ratio is close to infinity.(2)The coefficient of speed non-uniformity of mechanical system is used as the evaluation index of transmission stability of CVT.In order to make the output speed of CVT stable,the swing arm contour curve and cam contour curve are designed by using the reverse method.According to the change rule of the output speed of the rocker arm linearly increasing with time,the swing arm speed is controlled to change according to a certain rule to realize the reverse compensation of the output speed,so as to improve the output stability of CVT.(3)According to the performance requirements of CVT,the transmission mechanism,reset mechanism and transmission mechanism based on cam drive CVT are designed in detail.In addition,the transmission efficiency of mechanical system of CVT is calculated,and the running direction of CVT transmission mechanism is determined.Through a set of actual parameters,the three-dimensional modeling of CVT parts and the structural design of principle prototype are completed.(4)Based on the kinematics simulation function of NX10 software,the transmission mechanism of CVT is simulated.It is verified that CVT can realize CVT,and the CVT has continuous and stable motion output within a certain range.The CVT can be used in occasions with large transmission ratio and low requirements for transmission stability.