US 4,429,620 A · Hydraulically operated actuator

Abstract

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.

Claims37

Dependent claims

Apparatus comprising:

a housing having an inner wall and containing at least two linearly spaced-apart chambers;
a piston arranged for reciprocation in one of said chambers in a power stroke and in a return stroke;
reciprocative means connected to said piston for movement therewith and extending from said one chamber into said other chamber;
an annular space formed between said reciprocative means and the inner wall of said housing;
and
metal seal ring means operable to seal upon compression sealing off fluid communication between said chambers only at the completion of the power stroke and at the completion of the return stroke of said piston, said metal seal ring means comprising two metal seal ring units, one of said seal ring units being resiliently compressed to close off said annular space and seal off fluid communication between said chambers at the completion of the power stroke of said piston and the other of said metal seal ring units being resiliently compressed to close off said annular space and seal off fluid communication between said chambers at the completion of the return stroke of said piston.

3 more elements

Apparatus comprising:

a housing having an inner wall and containing at least two linearly spaced-apart chambers;
a piston arranged for reciprocation in one of said chambers in a power stroke and in a return stroke;
said chamber being formed in two parts;
seal means being resiliently compressed for sealing off fluid communication between said parts only at the end of the power stroke of said piston;
reciprocative means connected to said piston for movement therewith and extending from said one chamber into said other chamber;
a first annular space formed between said reciprocative means and the inner wall of said housing;
an actuator means connected to said reciprocative means and movable in said other chamber and extending from said housing;
a first metal seal ring unit operable to seal upon resilient compression sealing off fluid communication only at the completion of the power stroke of said piston to close off said first annular space;
a second metal seal ring unit operable to seal upon resilient compression sealing off fluid communication only at the completion of the return stroke of said piston to close off said first annular space;
a second annular space formed between said actuator rod and the inner wall of said housing;
a third metal seal ring unit operable to seal upon resilient compression sealing off fluid communication only at the completion of the return stroke of said piston to close off said second annular space;
first deformable means arranged on said reciprocative means and capable of deforming to allow simultaneous seals to be obtained by said seal means and by said one metal seal ring unit at the completion of the power stroke of said piston;
and
second deformable means arranged on said actuator rod and capable of deforming to allow simultaneous seals to be obtained by said second metal seal ring unit and by said third metal seal ring unit at the completion of the return stroke of said piston.

11 more elements

Dependencies are inferred from the claim text.

Hydraulically operated actuator

Life of this patent

Hydraulically operated actuator

Life of this patent

Abstract

Claims37