Expansible chamber devices – With releasable stop or latch means to prevent movement of... – Means includes element interfitting between working member...
Reexamination Certificate
2001-05-30
2003-11-04
Look, Edward K. (Department: 3745)
Expansible chamber devices
With releasable stop or latch means to prevent movement of...
Means includes element interfitting between working member...
C092S129000, C092S140000
Reexamination Certificate
active
06640688
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to actuator assemblies for use in moving a driven member, such as, for example, for rotating the stem of a valve. In particular, the present invention relates to actuator assemblies that are (a) lockable to prevent inadvertent movement of the driven member and (b) operative to permit a predetermined, limited movement of the driven member.
2. Description of the Prior Art
Valves, such as quarter-turn valves, e.g., butterfly valves, ball valves, etc., are commonly used to control fluid flow through flow conduits. Such valves commonly include a rotatable valve element disposed in a valve body, the valve element being rotatable between open and closed positions. Typically, there is a stem connected to the valve element that can be rotated to thereby rotate the valve element. Such rotation can be effected manually, but more frequently, the valve stem is connected to an actuator, which can be hydraulic, pneumatic, mechanical, electrical, etc.
In many instances, by governmental regulation or otherwise, it is desirable to provide security in the form of a locking mechanism to lock a valve in either an open or closed position to prevent unauthorized and unintended operation of the valve. For example, in a case where maintenance is being performed in a system of which the valve forms a part, it is desirable to lock the valve in the closed position so that the maintenance can be carried on safely and without the likelihood that the valve will be inadvertently opened. In this regard, it is also desirable that any valve-locking mechanism include an indicator that informs an observer of the position of the valve—i.e., opened or closed. In the aforementioned Continuation-in-Part Application Ser. No. 09/648,328, incorporated herein by reference for all purposes, there is disclosed an actuator assembly, which is lockable, to prevent inadvertent movement of a driven member, e.g., the rotatable stem of a valve.
Additionally, it may be desirable to test a valve's operability, such as in circumstances wherein a valve is called upon to function only rarely. An example may be in the case of an emergency shutdown valve (ESV), whose typical function, in an emergency, is to move to a fully closed position. Usually, ESVs are in an open position and remain in that condition for extended periods of time. Because the ESVs remain in an open position for retracted periods of time, it is possible for the valve element to become frozen in that position due to corrosion, buildup of process media, or the like. Even if not in the frozen state, such corrosion or buildup of process media may dramatically increase the time and torque necessary to move the valve element to the closed position. In either situation—i.e., whether the valve element be completely frozen and thereby require greater output torque than can be delivered by the actuator, or partially frozen such that the time required to close the valve is unacceptably long—there is a potential for loss of life and property. While it is possible to periodically close an ESV to test its operability, this requires disruption of the process in which the ESV is operating. Accordingly, it would be desirable to have an actuator assembly that could “exercise” the valve—i.e., test its operability—by moving the valve element a limited, predetermined amount, provision being made such that the valve element cannot be totally moved to any extreme, generally closed, position during the exercising procedure.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an actuator assembly that can selectively control the degree of movement of a driven member to which the actuator assembly is attached.
It is therefore an object of the present invention to provide a selectively lockable actuator assembly used to effect movement of a driven member.
Another object of the present invention is to provide a selectively lockable actuator assembly for use with a valve, such as a quarter-turn valve.
Another object of the present invention is to provide a selectively lockable actuator assembly, which provides an indication of the condition, e.g., position, of the driven member to which the actuator assembly is attached.
Still a further object of the present invention is to provide an actuator assembly that permits a predetermined, limited movement of a driven member.
Still a further object of the present invention is to provide an actuator assembly that is operative to permit a predetermined, limited movement of the valve element of an ESV or the like.
The above and other objects of the present invention will become apparent from the drawings, the description given herein, and the appended claims.
In one embodiment, the actuator assembly of the present invention includes a prime mover and a shaft having a first end and a second end, the shaft being operatively connected to the prime mover for reciprocal movement. The actuator assembly further includes a frame, the shaft being reciprocably movable in the frame. A linkage is attached to the frame and operatively connected to the shaft, the linkage being movable between a first position and a second position in response to reciprocal movement of the shaft. There is a selectively engageable stroke-limiting assembly operatively connected to the shaft for controlling movement of the shaft when the stroke-limiting assembly is engaged.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is an elevational view, partly in section, showing one embodiment of the actuator assembly of the present invention with the actuator assembly in a first position;
FIG. 2
is a view similar to
FIG. 1
showing the actuator assembly in a second position;
FIG. 3
is a view similar to
FIG. 1
showing the actuator assembly in an adjusted position relative to
FIG. 1
;
FIG. 4
is an exploded view of one embodiment of the locking assembly used in the actuator assembly of the present invention;
FIG. 5
is an elevational view of the actuator assembly shown in
FIG. 1
being mounted on a valve shown in phantom;
FIG. 6
is a cross-sectional view taken along the lines
6
—
6
of
FIG. 5
;
FIG. 7
is a cross-sectional view taken along the lines
7
—
7
of
FIG. 5
;
FIG. 8
is an elevational view, partly in section, of another embodiment of the actuator assembly of the present invention;
FIG. 9
is an elevational view, partly in section, of another embodiment of the actuator assembly of the present invention;
FIG. 10
is an elevational view, partly in section, showing another embodiment of the actuator assembly of the present invention used as a stroke-limiting device but with the stroke-limiting feature disengaged;
FIG. 11
is a view similar to
FIG. 10
showing the stroke-limiting feature engaged; and
FIG. 12
is a view similar to
FIG. 10
but showing the use of two prime movers.
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patent: 47
Browning & Bushman P.C.
Leslie Michael
Look Edward K.
Tyco Flow Control, Inc.
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