Spring return rotary actuator
First Claim
1. An electrically powered spring return rotary actuator, comprising:
- a) a frame;
b) a gear train comprising at least first, second, and third mutually coupled gears mounted for rotation within the frame and further including a drive element, a spring element, and an output element, each element mounted for rotation about an axis and to transfer torque to and from one of the first, second, and third gears;
b) a torsion spring coupled at a first end to the spring element and at a second end to the frame, the torsion spring of the type to be wound up by rotation of the spring element in a first direction, and when wound, applying torque to the spring element in a second direction;
c) a spring element lock which is mounted on the frame and connected to the spring element, and having a first state locking the spring element against rotation, and a second state allowing rotation of the spring element;
d) a drive motor mounted on the frame and having a shaft connected to apply torque to the drive element responsive to application of power and locking the drive element responsive to absence of power; and
e) an output element lock having a stop element mounted on the frame and a cog element connected to the output element, and having a first state wherein the cog and stop elements cooperate to lock the output element against rotation in at least a first direction, and a second state allowing rotation of the output element;
wherein,when the spring element lock is in its second state and the output element lock is in its first state, motor torque is applied through the motor shaft, the drive element, and the gear train to the spring element to wind the torsion spring;
torque applied by the motor to the drive element when the spring element lock is in its first state applies torque through the gears to the output element; and
when the output element lock is in its second state, power is absent, and the torsion spring is wound, the torsion spring applies torque to the output element through the spring element and the gears.
1 Assignment
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Accused Products
Abstract
A rotary actuator uses a two degree of freedom gear train with three torque members to provide torque to the output element from a first torque member. The torque is supplied to a second torque member from a drive motor. A torsion spring on the third torque member is normally wound tight and held wound by a brake which locks the third torque member during normal operation when electrical power is available for the drive motor. When power is lost, the brake releases the third torque member, allowing the spring to apply torque to the third torque member to drive the output element through the first torque member to a return position. This allows loads such as valves to be returned to a safety condition upon loss of electrical power to the system of which the load and the actuator are a part.
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Citations
11 Claims
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1. An electrically powered spring return rotary actuator, comprising:
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a) a frame; b) a gear train comprising at least first, second, and third mutually coupled gears mounted for rotation within the frame and further including a drive element, a spring element, and an output element, each element mounted for rotation about an axis and to transfer torque to and from one of the first, second, and third gears; b) a torsion spring coupled at a first end to the spring element and at a second end to the frame, the torsion spring of the type to be wound up by rotation of the spring element in a first direction, and when wound, applying torque to the spring element in a second direction; c) a spring element lock which is mounted on the frame and connected to the spring element, and having a first state locking the spring element against rotation, and a second state allowing rotation of the spring element; d) a drive motor mounted on the frame and having a shaft connected to apply torque to the drive element responsive to application of power and locking the drive element responsive to absence of power; and e) an output element lock having a stop element mounted on the frame and a cog element connected to the output element, and having a first state wherein the cog and stop elements cooperate to lock the output element against rotation in at least a first direction, and a second state allowing rotation of the output element;
wherein,when the spring element lock is in its second state and the output element lock is in its first state, motor torque is applied through the motor shaft, the drive element, and the gear train to the spring element to wind the torsion spring;
torque applied by the motor to the drive element when the spring element lock is in its first state applies torque through the gears to the output element; and
when the output element lock is in its second state, power is absent, and the torsion spring is wound, the torsion spring applies torque to the output element through the spring element and the gears. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification