具有刚性冲击的卡当泵机构动力学研究

ON DYNAMICS ANALYSIS OF KARDANO MACHINE WITH PASSIVE CONSTRAINT

卡当泵机构的实时动力学仿真具有重要的研究价值。由于虚约束,该机构的动力学方程数少于未知量数,文中提出在对称假设下预先确定虚约束受力的数值算法。首先假设曲柄等速转动,获得某一活塞在一周期当中的受力。以该周期的活塞受力作为初始值进行实时计算机仿真。每仿真一个或多个周期,更新一次该周期虚约束受力。该算法具有普遍性。研究单槽卡当泵基本机构的动力学问题,考虑动力机机械特性、周期性阻力、滑块与导槽的摩擦力等实际因素。仿真结果表明:在匀速假设下各构件的运动光滑;滑块与导槽之间的正压力方向存在突变的情况,理论上存在刚性冲击和柔性冲击;在实时仿真的情况下,由于该突变正压力的存在,曲柄角速度的变化不光滑,而摩擦力的参与加剧了冲击的效果。

The live computing simulation of Kardano pump mechanism is worthy to study.The number of unknown quantity is less than the number of equations because of the passive constraints.The pre-deciding passive constrains force arithmetic was proposed under the symmetry hypothesis.Firstly,get the piston force in one period with uniform brace speed.Secondly,take the periodic force as the passive constraint force at the beginning of simulation.Thirdly,update the periodic force each one or more working period.The arithmetic has universality.The dynamics of simple Kardano pump with single groove was studied.Some actual factors were considered,such as motor mechanical behavior,periodic varied resistance and friction between slider and groove,etc.The live simulation result has three parts.（1）The movement is smooth under the hypothesis of brace uniform speed.（2）Because of the abrupt direction change of pressure between the slider and groove,this kind of mechanism has rigid and flexible impact during working.（3）The friction force aggravates the impact effect.