| 摘要 |
The present invention is directed to a rotary shaft seal assembly and, more particularly, to an assembly including a continuous, annular, but axially variable seal for providing hydrodynamic lubrication between the seal and rotating shaft. The seal assembly uses differential pressures to maintain the seal compressed as it wears. The present system is particularly useful in drilling motors utilizing the movement of drilling fluid under pressure to operate the motor parts and thereby to drive a drill bit. The abrasive drilling fluid environment in a borehole is detrimental to the moving parts in such a system, and especially destructive to the bearings and seals. The present system utilizes a sealing member arranged in a continuous, annular, but axially variable path between the rotating shaft and housing of such a motor. Annular seal mounting members are positioned above and below the seal and have surfaces to matingly engage the seal member. The mounting elements are arranged to move relative to one another. A pressure differential developed across the motor is communicated to the respective mounting elements to urge the elements toward one another and thereby compress the seal member therebetween to accommodate wear take-up on the seal member. An oil chamber above the upper mounting element communicates drilling fluid pressure inside the drill pipe to the upper mounting element. The pressure of the annular space below the motor housing is communicated to the lower mounting element by means of a lower chamber.
|
