Valve actuator
First Claim
1. A valve actuator comprising:
- a body;
an electric motor;
a stem having a longitudinal axis extending through the body;
first coupling means for coupling the stem to a valve such that axial movement of the stem opens and closes the valve;
an outer shaft arranged coaxially around the stem and in threaded engagement therewith;
second coupling means coupling the shaft to the electric motor to cause rotational and thus axial movement of the shaft relative to the stem;
a solenoid-actuated latching mechanism including a cylindrical cap which is axially movable and has an internal surface formed with at least one recess, a spring retained by said cap, a plurality of retaining members held in a fixed axial position with the cap being axially movable relative thereto, and a wedge member; and
at least one solenoid which when activated moves the wedge member to push said retaining members outwardly with respect to said longitudinal axis and to hold them in engagement with said at least one recess, whereby the shaft is releasably retained in a predetermined axial position with the spring held in a compressed state, further rotation of the shaft causing reciprocating axial movement of the stem relative to the shaft to actuate the valve, and de-activation of the at least one solenoid releasing the shaft to allow axial movement of both the shaft and the stem, under action of the spring, in order to close the valve;
said wedge member and said retaining members being made of a material having a predetermined angle of friction and said wedge member having a face which engages with said retaining members and which is formed at an angle with respect to said longitudinal axis, said angle being substantially close to said angle of friction so as to provide a sufficient mechanical advantage to enable said at least one solenoid to retain the spring in its compressed state.
2 Assignments
0 Petitions
Accused Products
Abstract
A valve actuator comprises a stem extending through the actuator body for coupling to a valve such that axial movement of the stem opens and closes the valve. An outer shaft is arranged coaxially around, and in threaded engagement with the stem and is coupled to an electric motor for conveying rotational drive to the shaft and thus axial movement of the shaft relative to the stem against a spring bias. The shaft is releasably retained in a predetermined position by a solenoid-actuated latching mechanism with the spring in a compressed state, such that further rotation of the shaft causes axial movement of the stem relative to the shaft to actuate the valve. Deactuation of the mechanism releases the shaft to allow axial movement of both the shaft and the stem, under action of the spring in order to close the valve. The latching mechanism includes a plurality of retaining members which engage with an angled face of a wedge member, the angle of the wedge face with respect to the longitudinal axis of the stem being close to the angle of friction of the material of which the wedge member and retaining members are made.
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Citations
7 Claims
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1. A valve actuator comprising:
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a body; an electric motor; a stem having a longitudinal axis extending through the body; first coupling means for coupling the stem to a valve such that axial movement of the stem opens and closes the valve; an outer shaft arranged coaxially around the stem and in threaded engagement therewith; second coupling means coupling the shaft to the electric motor to cause rotational and thus axial movement of the shaft relative to the stem; a solenoid-actuated latching mechanism including a cylindrical cap which is axially movable and has an internal surface formed with at least one recess, a spring retained by said cap, a plurality of retaining members held in a fixed axial position with the cap being axially movable relative thereto, and a wedge member; and at least one solenoid which when activated moves the wedge member to push said retaining members outwardly with respect to said longitudinal axis and to hold them in engagement with said at least one recess, whereby the shaft is releasably retained in a predetermined axial position with the spring held in a compressed state, further rotation of the shaft causing reciprocating axial movement of the stem relative to the shaft to actuate the valve, and de-activation of the at least one solenoid releasing the shaft to allow axial movement of both the shaft and the stem, under action of the spring, in order to close the valve; said wedge member and said retaining members being made of a material having a predetermined angle of friction and said wedge member having a face which engages with said retaining members and which is formed at an angle with respect to said longitudinal axis, said angle being substantially close to said angle of friction so as to provide a sufficient mechanical advantage to enable said at least one solenoid to retain the spring in its compressed state. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification