滚筒式抽油机无切换换向机构设计

New reverse mechanism for drum type pumping unit

换向机构是滚筒式抽油机的主要部件。无切换换向机构是在分析以往滚筒式抽油机机械换向机构的基础上设计出的一种新式换向机构。它的主要原理是采用大摆角正反转的曲柄－齿轮、齿条换向机构，把电动机的旋转运动转变为小齿轮的往复摆动；小齿轮的往复摆动可通过滚筒、柔性件及天车轮转变为悬点的上下直线运动。介绍了这种换向机构的结构特点、运动及动力分析情况。采用这种换向机构设计出了滚筒式抽油机。分析、计算及设计实例表明，无切换换向机构对减少和消除滚筒式抽油机换向时引起的冲击是十分有效的。由于在换向机构内增加了减速齿轮，所需减速器的尺寸也相应减小。采用这种机构设计出的滚筒机具有结构紧凑、重量轻及减速器寿命长等优点。

A new reverse mechanism for drum type pumping units is developed. It adopts large swing angle crank-gear-rack mechanism to convert the rotating motion of the motor into swinging motion of.the small gear that is then convelted to the rectilinear motion of the polished rod through the drum, flexible elements and the crown sheave. The design features of the new reverse mechanism is introduced, and kinematic and dynamic analyses are conducted. Calculation shows that, by adopting the new mechanism, the reverse impact of the drurn type pumping unit can be eliminated or avoided effectively.A reducing gear is added in the reverse mechanims, therefore the size of the gear reducer is .decreased. The drum type pumping unit with the new reverse mechanism has the advantages of impact structure, light weight and extended gear reducer life.