rotary valve, system for directing a drill bit with a rotary valve, and method for maintaining engagement between surfaces on a rotary valve

摘要

A rotary valve can include a seat and a rotary actuator, each with a surface, the rotary actuator rotatably mounted in a housing. Surfaces can form a seal due to engagement with a engagement force used to maintain engagement. A bypass device can raise the pressure in a sealed volume in the valve to a constant level above an external pressure. The high pressure can produce a pressure differential through the rotary actuator, thereby producing at least a portion of the engaging force. Another deflection device can act between a splined hub and a coupled splined shaft, thereby applying at least a portion of the engagement force through the shaft to the rotary actuator. Fluid flowing through a screen can create a pressure drop, causing a pressure differential across the rotary actuator and applying at least a portion of the engagement force to the surfaces.