Rotary valve actuator

Abstract

A rotary actuator for a valve includes a cam mechanism for transmitting opening force to a movable valve member to move the valve member off a valve seat, against the bias of a closing spring. The cam mechanism does not transmit spring force to the valve member when the valve member is being moved to the closed position or is in the closed position. Also, the parts of the cam mechanism have a large surface area of contact when the valve is in the open position, to minimize unit loading of the cam surfaces. The movable cam is movable axially relative to the actuator handle. The movable valve member is blocked from rotation relative to the valve body. The cam mechanism does not transmit spring force to the movable valve member when the valve member is in the closed position.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a valve and an actuator for a valve. In particular, the present invention relates to a valve having an actuator responsive to rotational input for moving a first valve part axially between open and closed positions relative to a second valve part. [0002] Many industrial valves have a valve member, such as a valve stem, that is movable relative to a valve seat between an open position spaced apart from the seat, enabling fluid flow through the valve, and a closed position in engagement with the valve seat. The movable valve member is often held in engagement with the valve seat by a spring. Over time, the valve member and / or the valve scat may wear, or under continued loading experience material creep, especially if made from plastic. If the valve member is not able to move farther toward the valve seat to compensate for such wear or creep, the valve may not close completely in some circumstances. [0003] Some valves ...

AI Technical Summary

Benefits of technology

"The present invention is about a valve and a rotary actuator for the valve. The actuator includes a cam mechanism that only transmits opening force to the valve member to move it off the valve seat, against the bias of a closing spring. The cam mechanism does not transmit closing spring force to the valve member when it is being moved to the closed position or is in the closed position. This allows the spring to compensate for any material creep or deformation in the valve member or the valve seat. The cam mechanism includes two cams each having a full cam profile, rather than a cam and follower, to decrease unit loading on the cam surfaces. The movable cam is movable axially relative to the actuator handle. The movable valve member is blocked from rotation relative to the valve body to minimize wear of the valve seat and of the portion of the valve member that engages the valve seat. The cam mechanism does not transmit spring force to the movable valve member when it is in the closed position."

Problems solved by technology

Over time, the valve member and / or the valve scat may wear, or under continued loading experience material creep, especially if made from plastic.

If the valve member is not able to move farther toward the valve seat to compensate for such wear or creep, the valve may not close completely in some circumstances.

If the cam mechanism is interposed between the closing spring and the movable valve member, the cam mechanism may undesirably limit compensating movement of the valve member.

In addition, the parts of the cam mechanism, themselves, if made from plastic, may be subject to material creep and / or deformation if subjected to the force of the closing spring for an extended period of time.

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