Fail safe valve actuator
First Claim
1. A fail safe valve actuator comprising a housing for mounting on a valve body, a valve stem having one portion adapted to be connected to the valve member of a valve and another portion having an elongated helical groove in its outer surface, means mounting the valve stem in the housing to reciprocate and thereby move the valve member between valve open and valve closed positions, compressible means for urging the valve stem toward one position, means for moving the valve member to its other position including a ball nut in engagement with the helical groove on the valve stem and mounted in the housing for rotation relative to the valve stem, an electric motor having an output shaft, a centrifugal clutch connected to the output shaft of the electric motor that will engage and transmit torque when the motor reaches a preselected speed of rotation, means for transmitting the torque from the centrifugal clutch to the ball nut to rotate the nut and move the valve stem and valve member to one position, and electrically powered means for holding the stem and valve member in said one position and then releasing the valve stem and valve member for movement by the compressible means to the other position when the electrical power fails.
3 Assignments
0 Petitions
Accused Products
Abstract
A fail safe valve actuator is disclosed that is powered by an electric motor. A valve stem with a helical groove is moved in one direction by a ball nut rotated by the electric motor to move a valve member to its operating position. The valve member is held in operating position by a solenoid. When power fails, a spring moves the valve stem in the other direction to move the valve member to its fail safe position. A torque limiting device protects the electric motor from the high torque created when the valve stem abruptly stops moving when the valve member reaches its operating position. A centrifugal brake absorbs a portion of the energy released when the power fails and the valve stem is moved rapidly to its fail safe position by the spring.
-
Citations
39 Claims
- 1. A fail safe valve actuator comprising a housing for mounting on a valve body, a valve stem having one portion adapted to be connected to the valve member of a valve and another portion having an elongated helical groove in its outer surface, means mounting the valve stem in the housing to reciprocate and thereby move the valve member between valve open and valve closed positions, compressible means for urging the valve stem toward one position, means for moving the valve member to its other position including a ball nut in engagement with the helical groove on the valve stem and mounted in the housing for rotation relative to the valve stem, an electric motor having an output shaft, a centrifugal clutch connected to the output shaft of the electric motor that will engage and transmit torque when the motor reaches a preselected speed of rotation, means for transmitting the torque from the centrifugal clutch to the ball nut to rotate the nut and move the valve stem and valve member to one position, and electrically powered means for holding the stem and valve member in said one position and then releasing the valve stem and valve member for movement by the compressible means to the other position when the electrical power fails.
- 8. A fail safe valve actuator comprising a housing for mounting on a valve body, a valve stem having one portion adapted to be connected to the valve member of a valve and another portion having an elongated helical groove in its outer surface, means mounting the valve stem in the housing to reciprocate and thereby move the valve member between valve open and valve closed positions, compressible means for urging the valve stem toward one position, means for moving the valve stem to its other position including a ball nut in engagement with the helical groove on the valve stem and mounted in the housing for rotation relative to the valve stem, an electric motor having an output shaft, means for transmitting the torque from the electric motor to the ball nut to rotate the nut and move the valve stem and valve member to one position, including a torque limiting device to disconnect the electric motor from the torque transmitting means when the torque reaches a preselected amount, and electrically powered means for holding the stem and valve member in said one position and then releasing the valve stem and valve member for movement by the compressible means to the other position when the electrical power fails.
- 20. A fail safe valve actuator comprising a housing for mounting on a valve body, a valve stem having one portion adapted to be connected to a valve member of the valve and another portion having an elongated helical groove in its outer surface, means mounting the valve stem in the housing to reciprocate and thereby move the valve member between valve open and valve closed positions, compressible means for urging the valve stem toward one position, means for moving the valve stem to its other position including a ball nut in the housing in engagement with the helical groove on the valve stem and mounted in the housing for rotation relative to the valve stem, an electric motor having an output shaft, a centrifugal clutch connected to the output shaft of the electric motor that will engage and transmit torque when the motor reaches a preselected speed of rotation, means for transmitting the torque from the centrifugal clutch to the ball nut to rotate the nut and move the valve stem and valve member to one position including a torque limiting device that will disconnect the centrifugal clutch from the ball nut when the torque reaches a preselected amount, electrically powered means for holding the stem and valve member in one position and then releasing the valve stem and valve member for movement by the compressible means to the other position when the electrical power fails.
-
23. An actuator for a valve having a body and a closure member movable between alternate positions within the body, comprising
a housing for mounting on the valve body, a reversible drive mechanism comprising a first drive part supported for rotation in the housing and a second drive part engageable with the first drive part, and connectible to the closure member for moving it to one of its positions upon rotation of the first part in one direction, an electric motor for rotating the first drive part in one direction, means yieldably urging the second drive part in a direction to move the closure member to its other position, electrically powered means for preventing said first drive part from rotating in said opposite direction and thus holding the closure member in its one position, means for releasing said rotation preventing means to permit said closure member to be moved by said urging means to its other position in response to the loss of the supply of electrical power to said, rotation preventing means, and a torque limiting device for disconnecting the motor shaft and said first drive part in response to the transmission of a predetermined torque therebetween.
-
29. An actuator for a gate valve having a body and a rising stem for moving the gate between alternate positions within the body, comprising
a housing for mounting on the valve body, a reversible drive comprising a first drive part supported for rotation in the housing and a second drive part engageable with the first drive part and connectible to the stem for moving the gate to one of its positions upon rotation of the first part in one direction, an electric motor for rotating the first drive part in one direction, means yieldably urging the second drive part in a direction to move gate to its other position, electrically powered means for preventing said drive part from rotating in said opposite direction and thus holding the gate in its one position, means for releasing aid rotation preventing means to permit said gate to be moved by said urging means to its other position in response to the loss of the supply of electrical power to said rotation preventing means and means which is independent of the rotation preventing means for dissipating the energy due to line fluid in the valve body acting over the stem and the means with which said second drive part is urged to its other position upon release of said rotating preventing means in proportion to the velocity with which said second part is moved toward its other position.
-
32. An actuator of the character defined in 30, wherein
said rotation preventing means comprises a first member having a first cylindrical surface which is rotatable with the first drive part, a second member having a second cylindrical surface aligned with the first cylindrical surface of the first member and rotatable in response to the rotation of motor shaft, a wrap spring surrounding the first and second cylindrical surfaces with one end connected to the second member, and stop means engageable with the other end for causing the spring to be wrapped tightly about the surfaces to rotate the first member with the second member, and said releasing means comprises means for removing said stop means to permit the spring to expand and thus permit said first member to rotate relative to said second member.
- 34. An actuator for a valve that is opened and closed by the reciprocation of a valve member comprising a housing for mounting on the valve, a valve stem in the housing for connecting to a valve member, a portion of the valve stem having an external helical groove, a ball nut housing balls in engagement with the helical groove on the valve stem, means mounting the ball nut for rotation relative to the valve stem to move the stem longitudinally in one direction to a first position to open or close the valve, resilient means positioned in the housing to be compressed by the movement of the stem in said one direction, and electrically powered means for rotating the ball nut to move the stem to said first position including an electric motor having a first output shaft, a centrifugal clutch mounted on the first output shaft that will engage and drive a second output shaft when the output shaft of the motor reaches a preselected speed of rotation to provide a soft starting torque to the second shaft, a torque limiting device having a third output shaft and connected to the second shaft, and means for transmitting the torque from a third output shaft to the ball nut to rotate the nut and move the valve stem longitudinally to move the valve member to one of said positions, said torque limiting device disconnecting the third shaft from the second shaft when the torque reaches a preselected amount, and electrically powered means for holding the valve member in said position and then releasing the valve member for movement by the resilient means to the other position should the electricity supplied to the holding means be shut off.
-
36. An actuator for a valve having a body and a closure member movable between alternate positions within the body, comprising
a housing for mounting a valve body, a reversible drive mechanism comprising a first drive part supported for rotation in the housing and a second drive part engageable with the first drive part, and connectible to the closure member for moving it to one of its positions upon rotation of the first part in one direction, an electric motor having a rotary shaft, clutch means for rotating first drive part in said one direction in response to rotation of the motor shaft but enabling said first drive part to rotate in the opposite direction without rotating the motor shaft, means yieldably urging the second drive part in a direction to move the closure member to its other position, electrically powered means for preventing said first drive part from rotating in said opposite direction and thus holding the closure member in its one position, means for releasing said rotation preventing means to permit said closure member to be moved by said urging means to its other position in response to loss of the supply of electrical power to said rotation preventing means, and means for reducing the speed of the motor shaft which is transmitted to the first drive part including a gear train connected between the clutch means and said first drive part.
-
37. An actuator for a valve having a body and a closure member movable between alternate positions within the body, comprising
a housing for mounting a valve body, a reversible drive mechanism comprising a first drive part supported for rotation in the housing and a second drive part engageable with the first drive part, and connectible to the closure member for moving it to one of its positions upon rotation of the first part in one direction, an electric motor having a rotary shaft, clutch means for rotating first drive part in said one direction in response to rotation of the motor shaft but enabling said first drive part to rotate in the opposite direction without rotating the motor shaft, means yieldably urging the second drive part in a direction to move the closure member to its other position, electrically powered means for preventing said first drive part from rotating in said opposite direction and thus holding the closure member in its one position, and means for releasing said rotation preventing means to permit said closure member to be moved by said urging means to its other position in response to loss of the supply of electrical power to said rotation preventing means, said clutch means including means which is responsive to centrifugal force so as to connect the motor shaft to said first drive part only when the motor shaft attains a given speed.
-
38. An actuator for a valve having a body and a closure member movable between alternate positions within the body, comprising
a housing for mounting a valve body, a reversible drive mechanism comprising a first drive part supported for rotation in the housing and a second drive part engageable with the first drive part, and connectible to the closure member for moving it to one of its positions upon rotation of the first part in one direction, an electric motor having a rotary shaft, clutch means for rotating first drive part in said one direction in response to rotation of the motor shaft but enabling said first drive part to rotate in the opposite direction without rotating the motor shaft, means yieldably urging the second drive part in a direction to move the closure member to its other position, electrically powered means for preventing said first drive part from rotating in said opposite direction and thus holding the closure member in its one position, and means for releasing said rotation preventing means to permit said closure member to be moved by said urging means to its other position in response to loss of the supply of electrical power to said rotation preventing means, said rotation preventing means including a first member having a first cylindrical surface which is rotatable with the first drive part, a second member having a second cylindrical surface aligned with the first cylindrical surface of the first member and rotatable in response to the rotation of motor shaft, a wrap spring surrounding the first and second cylindrical surface with one end connected to the second member, and stop means engageable with the other end for causing the spring to be wrapped tightly about the surfaces to rotate the first member with the second member, and said releasing means comprises means for removing said stop means to permit the spring to expand and thus permit said first member to rotate relative to said second member.
-
39. An actuator for a valve having a body and a closure member movable between alternate positions within the body, comprising
a housing for mounting a valve body, a reversible drive mechanism comprising a first drive part supported for rotation in the housing and a second drive part engageable with the first drive part, and connectible to the closure member for moving it to one of its positions upon rotation of the first part in one direction, an electric motor having a rotary shaft, clutch means for rotating first drive part in said one direction in response to rotation of the motor shaft but enabling said first drive part to rotate in the opposite direction without rotating the motor shaft, means yieldably urging the second drive part in a direction to move the closure member to its other position, electrically powered means for preventing said first drive part from rotating in said opposite direction and thus holding the closure member in its one position, and means for releasing said rotation preventing means to permit said closure member to be moved by said urging means to its other position in response to loss of the supply of electrical power to said rotation preventing means, one of said drive parts being a nut having helical grooves therein, the other drive part being a screw having helical grooves thereabout and extending through the nut, and anti-friction elements being disposed between them for rolling within the helical grooves of both.
Specification