Research On Dynamics Of The Crank-group Driving Mechanism With Clearance

The crank-group driving mechanism, a new type of transmission mechanism, can realize the synchronous transmission among multiple parallel axis. Based on the theory and research on the planar linkage mechanism with clearance as well as the balance of the planar linkage mechanism, the dynamics of the crank-group driving mechanism with clearance is studied in the thesis. The kinematic and force analysis for ideal crank-group mechanism is completed. And, the theoretical research, virtual simulation and experimental verification on issue of inertia force balance of this mechanism is completed. Moreover, the dynamic theory analysis of the crank-group driving mechanism with clearance is completed, and the dynamic model is established based on the continuous contact model. In the end, by the contrast analysis of the virtual simulation software ADAMS, the impact of clearance on this mechanism as well as the method for controlling the impact are put forward. The main works of this thesis are described as follows:(1)The evolution process from a parallel double crank mechanism to the crank-group driving mechanism is summarized and analyzed. Regardless of clearance, the kinematic and forcing analysis for the basic unit-parallel double crank mechanism is finished, and the dynamic model is established. On this basic and according to the motion specifications, the dynamic balancing equation of the crank-group mechanism is derived progressively. In addition, the dynamic model and mathematical model are established, and the method of solving this model is simply mentioned.(2)The approach to balancing the inertia force in a plane is produced based on mass substitution method and linear independent vector method. And, the balancing condition is derived. Then, by an example, the value of balance quality of six-crank mechanism is figured out in the method as described above. In the end, using the simulation software ADAMS, the contrast results show that total center-of-mass of this mechanism before and after counterweight. Thus, the rectness of balance theory is verified.(3)This thesis point out that the crank-group mechanism is a kind of multiple clearance mechanism with redundant virtual constraint. The kinematic and dynamic analysis for the basic unit-parallel double crank mechanism with clearance is finished, and the dynamic model based on the continuous contact model and Lagrange’method is established. Moreover, the dynamic model of the crank-group mechanism with clearance are progressively established, and the method of solving this model is simply mentioned. In the multibody dynamics simulation software ADAMS, the simulation model is established. And, the dynamic characteristics are contrasted and analyzed, when the situation are different, namely, the different clearance radius, different speed. The impact of clearance on this mechanism as well as the method for controlling the impact are put forward.(4)It is verified the rectness of theory on balance of crank-group driving mechanism by experiment. We design and manufacture the experiment set, and measure the acceleration fluctuation in this mechanism by piezoelectric acceleration sensor. The data is collected and analyzed by the general dynamic signal test and analysis system-DH5922N. By contrasting the acceleration fluctuation, the rectness of theory on balance is verified.The innovation of this thesis:(1) The research method, from unit to whole. Based on the characteristic of evolution process from a parallel double crank mechanism to the crank-group driving mechanism, the basic unit - parallel double crank mechanism is firstly researched. Then, the crank-group driving mechanism is progressively researched. (2) Double route and contrast. By contrasting ideal mechanism and with clearance, simulation and experiment, the rectness of result is verified.