US 4,744,386 AGranted

Modular hydraulic actuator

AssigneeCameron Iron Works USA, Inc.

InventorNeil F. Frazer

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Abstract

A surface safety valve hydraulic actuator of modular construction. The actuator includes separately installable, removable, and interchangeable wirecutting and non-wirecutting spring modules, used with the same hydraulic cylinder and bonnet. The bonnet is attached to the body of the valve. A lower stem extends through a lower seal and into the valve body cavity, and is connected to the gate segments of the valve. A hydraulic cylinder is removably attached to the bonnet. An upper stem with a central bore is disposed in the cylinder chamber and carries a piston thereon, and extends through an upper seal in the top of the hydraulic cylinder. A spring module is removably attached to the hydraulic cylinder, and includes a spring can telescoped over the top of the cylinder. The spring can is rotatably connected to an annular spring retainer, which in turn is mounted on the cylinder. A coupling rod is inserted through the upper stem and screwed into the top of the lower stem. A spring coupler is connected to the upper end of the coupling rod, and bears upon the upper surface of a spring plate. In the non-wirecutting spring module, a single coil spring is disposed in the spring can between the spring plate and the spring retainer. In the wirecutting spring module, dual coil springs are used.

An actuator for a gate valve, the gate valve having a body with a flow passage therethrough and a cavity in the body, there being a gate disposed in the body cavity and reciprocable across the flow passage for alternately permitting and preventing the flow of fluids through the flow passage, comprising:

a bonnet having means disposed thereon for removably mountind the bonnet on the valve body, and lower stem means reciprocatingly disposed in the bonnet and having a lower portion adapted for extending into the valve body cavity and connecting to the gate and an upper portion extending out of the bonnet;
a hydraulic cylinder having a body and means disposed on said cylinder body for removably mounting said hydraulic cylinder on said bonnet, said hydraulic cylinder including upper stem means reciprocatingly disposed in said cylinder body and engaging said lower stem means, and means for supplying pressurized hydraulic fluid to said upper stem means for moving it downwardly in said cylinder, said lower stem means being moved downwardly along with said upper stem means;
and
a spring module including a body having means disposed thereon for removably mounting said spring module around said hydraulic cylinder, spring means disposed in said spring module body, and removable means connected between said spring means and said lower stem means for compressing said spring means when said lower stem means is moved downwardly and for lifting said lower stem means upwardly when said pressurized hydraulic fluid is removed from said upper stem means and said spring means is allowed to expand said spring module body having upper and lower retaining means disposed at its upper and lower ends, respectively, for retaining said spring means in said spring module body and for enabling removal of said spring module body and said spring means as a unit from said hydraulic cylinder when said removable means connected between said spring means and said lower stem means has been removed, whether said gate valve is open or closed and leaving said hydraulic cylinder in tact on said bonnet.

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Abstract

Claims23