投球控制机构的分析与研究

Research on Ball Dropping Control Mechanism

投球控制机构是一种特殊的变过流面积控制机构,广泛应用于井下控制工具中,但目前很少有专门针对投球控制机构的研究。投球控制机构可分为单次投球剪钉机构和多次投球弹簧机构,分别对这2种机构的结构与工作原理进行了分析;对小球的落体运动以及小球对球座的冲击力等问题进行了研究;对机构进行了动力学分析,建立了系统传递函数,研究了机构的控制特性,指出对于投球机构控制系统,若要提高系统的稳定性,应提高阻尼系数,或降低弹簧刚度和活塞机构质量;若要提高系统的快速性,应提高弹簧刚度或降低活塞机构质量。为保证系统的稳定性和快速性,需在实际工程设计中,找二者的平衡点。研究内容对井下控制工具中投球控制机构的设计具有指导意义。

Ball dropping control mechanism is a special variable flow area control mechanism which is widely used in downhole tools. But few research on the ball control mechanism has been conducted. The ball dropping control mechanism can be divided into two kinds： single ball drop shear mechanism and multiple ball drop spring mechanism. Structure and working principle of the two kinds of mechanism are analyzed. Failing motion and its impact force on the ball seat are studied. System transfer function is established based on dynamic analysis. Studies on the control characteristics of mechanisms show that, to enhance the stability of the system, the damping coefficient should be improved or the spring rate and piston mechanism quality be lowered. To reduce the system＇ s response time, the spring rate and piston mechanism quality should be increased. To achieve a better stability and shorter re- sponse time of the system, optimization should be conducted in the actual engineering design to find the balance. The research could provide valuable guidance for the design of ball dropping control mechanism of downhole tools.