TWO-JOINT DRIVE SHAFT OF BOTTOMHOLE MOTOR Russian patent published in 2011 - IPC E21B4/02 

FIELD: engines and pumps.

SUBSTANCE: two-joint drive shaft of bottomhole motor, which connects rotor and spindle shaft of motor, which are offset relative to each other, includes drive and driven hinge joints, each of which includes housing and semi-shaft, which are fixed from mutual turn with possibility of misalignment of their axes with rolling elements located in slots and cavities of housing and semi-shaft, thrust bearing including centre pad fixed in the housing and the stop attached to semi-shaft, working sliding surfaces of which have spherical shape, with centre located in plane of centres of rolling element, flexible cover and nut of housing, which restrict oil-filled cavity of hinge joint, thread on the housing of drive hinge joint for attachment to the rotor. At that, semi-shaft of drive hinge joint is attached to the housing of driven hinge joint; semi-shaft of driven hinge joint is outlet element of cardan with thread to be attached to spindle shaft. That is, hinge joints in cardan are located in series and in one direction. In both hinge joints the thrust bearing is located above the plane of centres of rolling elements. Equivalent cardan shafts have reflection symmetric location of hinge joints, which leads to the increase in number of original parts, their unbalance due to bad stream-lining with liquid flow. According to invention, cardan shaft has unidirectional in-series location of hinge joints.

EFFECT: stream-lining of cardan shaft is optimised, parts commonality is improved, service life is extended, its assembly and repair is simplified.

5 cl