链条抽油机无侧弯力矩换向平衡装置

针对现有链条抽油机换向平衡机构故障率高、可靠性差的问题，提出了无侧弯力矩换向平衡装置的设计方案，并进行了受力分析。这种装置采用双悬索结构，使悬点载荷、链条力和平衡力组成的力系处于传动链条运动平面内，消除了现有链条抽油机往返架前后方向的侧弯力矩。此外还增设了导向缓冲装置。这些措施改善了整机受力状况，提高了链条寿命，减少了换向冲击和导轨磨损。换向平衡装置集换向和平衡于一体，采用小重块平衡方式，平衡率达90％以上。现场应用表明，这种装置的可靠性明显优于现有链条抽油机的换向平衡机构，且结构简单，性能优良。

Lateral bending moment－free reverse and balance mechanism on chain-drive pumping units

In the light of the high failure rate and low reliability of the commnly uscd reverse and balance mechanism on achain－drive pumping unit, the design scheme for a lateral bending moment－free reverse and balance mechanism is put forward, and lelevant force analysis is conducted. The mechanism adopts a dual suspending rope structure making the Polished rod load, the forces on the chain and the balancing foree on the kinematic plane of the drive chain to eliminate thelateral bending moment on the reciprocating rack of the pumping unit. The mechanism also attaches a guiding buffer device. Therefore the force condition of the mechanism is improved, and the service life of the drive chain is prolonged, thereveral impact and wear of the guide are reduced. Additionally, the small countemeight balancing mode is applied andhigh balancing rate is achieved. Field test shows that the mechanism is simple and reliable.