心形曲柄导杆近似间歇机构分析与综合

Analysis and synthesis of the cardioid crank guide-bar mechanism with approximate dwell motion

心形曲柄是能够生成心形线的行星机构,用心形曲柄替代导杆机构的驱动曲柄,相当于导杆机构具有一个变化长度和速度、沿着心形线运动的曲柄,从而改变了导杆的运动特性。提出了心形曲柄导杆近似间歇运动机构,进行了机构运动分析,给出了间歇角、间歇窜动角、导杆极限位置、导杆摆角和行程速度变化系数等计算方法,讨论了中心距和行星连杆长度对机构运动性能的影响。用最小二乘法进行了机构的结构参数和性能参数逼近,得到了近似间歇运动机构的近似设计方法。

The cardioid crank is a planet mechanism which is able to generate cardioid curve;the cardioid crank is the driven force of the guide-bar mechanism. It is equal to the mechanism with a crank of varying length, speed and moving along the cardioid, which changes the kinematic characteristics of the guide-bar. In this article, approximate dwell motion of cardioid crank guide-bar is put forward;the kinematic analysis on the mechanism is carried out. The calculation methods for dwell angle, dwell movement angle, limit position of guide-bar, oscillate angle of guide-bar and time ratio are worked out. The influence of center distance and length of planetary linker on motion performance of the mechanism is explored. By means of the least square method, efforts are made to approximate the structural and performance parameters of the mechanism. The approximate method for the dwell motion mechanism is worked out.