HYDRAULICALLY OPERATED ACTUATOR

摘要

APPLICATION FOR UNITED STATES PATENT HYDRAULICALLY OPERATED ACTUATOR A hydraulically operated actuator employs multiple metal-to-metal static seals to isolate the hydraulic fluid and to isolate the actuator from surrounding contaminating (ambient) fluids. A housing contains at least two linearly spaced apart chambers. A piston reciprocates from a retracted position to an extended position (power stroke) and from the extended position to the retracted position (return stroke) in one of the chambers (hydraulic chamber). The hydraulic chamber is separated by the piston into two sections, one of which contains high pressure hydraulic fluid and the other of which contains low pressure hydraulic fluid. A first static metal seal ring unit is designed to seal first at the completion of the power stroke of the piston to isolate the low pressure hydraulic fluid section from external contaminating fluids which may be at a higher pressure. A second static metal seal ring unit is designed to seal at the completion of the return stroke of the piston also to isolate the low pressure section from external contaminating fluids. Power for the return stroke is primarily supplied by springs, with biasing pressure from the external environment providing a lesser contribution. A third static metal seal ring unit may be employed to obtain a simultaneous seal with the first metal seal ring unit to isolate the high pressure section from the low pressure section at the completion of the power stroke of the piston. Alternatively, an elastomer or a knife-edge metal-to-metal type static seal may be substituted for the third metal seal ring unit. Deformable means positioned adjacent the first metal seal ring unit ensures that the third metal seal ring unit effects a seal once the first metal seal ring unit effects its seal. The actuator may be employed to operate a subsurface safety valve used to control flow of fluids through a well tubing and may be located external of the well tubing with the piston being linked to a valve operator. Means may be provided to compensate for any differences in travel between the piston and valve operator.