Pressure compensation system for a steerable rotary drilling device

摘要

In a drilling apparatus of the type comprising a housing, a proximal seal, a distal seal, a fluid chamber defined by an interior of the housing between the proximal seal and the distal seal, the fluid chamber containing a lubricating fluid having a fluid chamber pressure, a pressure compensation system for compensating for the effects of an ambient pressure exerted on an exterior of the apparatus. The pressure compensation system includes a pressure port in the housing so that the ambient pressure can be communicated to the fluid chamber and a supplementary pressure source for exerting a supplementary pressure on the lubricating fluid contained in the fluid chamber so that the fluid chamber pressure is maintained higher than the ambient pressure.