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US 4,050,670 AGranted
Variable force actuator
AssigneeMasoneilan International, Inc.
InventorsKarl S. Borg, Gareth A. Keith
Life of this patent
Estimating the term…
Abstract
An actuator for reciprocating stem control valves having a linkage system affording variable force, reversible action, and adaptability to different valve strokes.
Claims19
An actuator for stroking a valve having a body and a plug stem projecting on an axis therefrom and shiftable between initial and final limit positions, comprising
- a yoke attached to said body and received over said plug stem;
- a powerhead fixedly associated with said yoke;
- an input thrust rod extending into said yoke from said powerhead and shifted by controlled fluid pressures on said powerhead;
- and
- a variable force linkage between said thrust rod and said plug stem, said linkage comprising
- a support shaft mounted in said yoke on said plug stem axis,
- a main lever pivotally mounted on said support shaft for rotating about said plug stem axis,
- a pivotal connection of said thrust rod to said main lever at a selected radius from said support shaft and at a selected angle from said plug stem axis,
- an output thrust link pivotally connected at its one end for shifting said plug stem, and
- a pivotal connection of the other output thrust link end to said main lever at a selected radius from said support shaft and at a selected angle from said plug stem axis,
- said link-lever connection separated from said rod-lever connection by a least one of their said selected radii and angles being differently chosen,
- for valve closing mechanical advantage of the output stroking of said thrust link over the input stroking of said thrust rod, and
- such that in valve closing the actuator output shifting of said plug stem by said output thrust link is at an increasingly varying rate of change of force relative to the actuator input rotation of said main lever by said input thrust rod.
10 more elements
An actuator for a control valve having a stem reciprocating on an axis comprising
- a yoke mountable at the valve and in line with said axis;
- a powerhead mounted on said yoke and comprising
- a flexible diaphragm arranged for rolling responsive to control fluid pressures thereon and
- an input thrust rod extending from said diaphragm into said yoke and for shifting by said diaphragm generally normally to said stem axis;
- a support shaft journalled in said yoke on said stem axis;
- a main lever rotatable on said shaft about said stem axis;
- said input thrust rod pivotally connected to said main lever at a selected radius from said shaft and at a selected angle from said stem axis;
- an axially extending stem connector;
- means in said yoke for reciprocating support of said stem connector;
- and
- an output thrust link pivotally connected at its one end for shifting said stem connector;
- said output thrust link pivotally connected at its other end to said main lever at a selected radius from said support shaft and at a selected angle from said stem axis;
- the main lever connection of said output thrust link separated from the main lever connection of said input thrust rod by at least one of their said selected radii and angles being differently chosen,
- for valve closing mechanical advantage of the output shifting of said stem connector over the input shifting of said thrust rod, and
- such that said mechanical advantage of the output thrust of said stem connector relative to the input thrust of said powerhead rod changes at a varying rate which increases as said stem connector closely approaches it full extended position of seating a down-closing valve.
12 more elements
Dependencies are inferred from the claim text.