使用混合杆柱时抽油泵柱塞的超冲程

任何抽油杆柱在理论上都可能产生超冲程，只是大小不同而已。超冲程的存在，使泵柱塞的有效冲程增大，甚至会大于光杆冲程。首次提出了抽油泵柱塞相对超冲程和绝对超冲程的概念，这将有助于正确认识玻璃钢抽油杆的作用和玻璃钢抽油杆的推广使用。将抽油杆柱简化成上端受光杆的激振位移、下端带有集中质量的弹簧－质量力学模型，建立了抽油杆柱纵向振动的偏微分方程和边界条件，然后用固有函数法求解方程，得出了抽油泵柱塞超冲程的无穷级数解析计算式。

Stroke of plunger on subsurface pump system with compound rod string

Theoretically any sucker rod string may work with excessive slroke The exist of excessive stroke will cause the increase of the effective stroke of the pump plunger, and this increased stroke is evcn larger than that of the polished rod.The concepts of relative excessive stroke and absolute excessive stroke: of subsurface pump plunger are put forward for thefirst time, and they will be helpful to better understanding of the role fiberglass reinforced Plastic sucker rod and to the popularization of the rod. The sucker rod string is simplified as a spring－mass mechanical model,thereby the partial differential equation and boundaty condition of the longiludinitl vib]ution of the rod string are established, then the equationis solved by using the inhelent funetion method, and the infinite series analytical formula for caleulating the excessivestroke of the subsurface pump plunger is obtained.