Mechanical stored energy positioning actuator

A rotary mechanical valve actuator having;

• a reversible motor;
• a torsional spring having upper and lower ends;
• a torque multiplier driven by said motor having an output shaft and a housing, said shaft attached to said spring lower end;
• a valve operating shaft having first and second ends, said first end attached to said spring upper end and said second end coupled to a valve;
• means indicating a predetermined position of said output shaft, relative said operating shaft;
• means responsive to said indicating means for signaling and reversing said motor;
• a latch responsive to said signal means for selectively and releasably limiting said output shaft motion relative said operating shaft to a predetermined value;
• a stop, limiting travel of said valve operating shaft relative said output shaft;
• wherein said drive motor and torque multiplier shaft, in sequence rotate said output shaft in a first direction thereby rotating said spring and operating shaft toward said stop, and, said shaft abutting said stop, winding said spring, actuating said signal means, and latching said output and operating shafts, thereby preventing further winding of said spring, and reversing said motor for rotation in a second direction;
• and, said output shaft provides torque to the valve operating shaft in first and second directions;
• whereupon loss of motor torque and latch signal said latch releases said shafts, allowing said spring to unwind, returning said output shaft to its original position.

In a rotary valve actuator of the type employing a reversible drive motor and a torsional spring for storing rotational energy, providing bidirectional valve operation, and on signal and/or loss of power to the actuator, returning the valve to a predetermined position, the improvement comprising;

• an output shaft on said drive motor fixed to one end of said spring;
• a valve shaft having upper and lower ends, movably contained and concentric with said output shaft;
• a reaction member, having one end attached to said output shaft adjacent to said spring attachment;
• a drive motor housing intermediate said spring reaction member and valve, containing said output and valve shafts, said housing upper end in rotatable abutment with said output shaft, adjacent said spring attachment;
• a disk, fixed to the other end of said spring, and attached to said valve shaft, adjacent said valve shaft upper end, whereby, on rotation of said output shaft, said spring member, spring and disk rotate said valve shaft;
• a stop, fixed to said valve shaft lower end limiting travel of said valve shaft relative to said drive motor housing, wherein valve shaft rotation in one direction turns the valve shaft against said stop, and further rotation in said one direction rotates said reaction member relative said valve shaft, winding said spring, and storing rotational energy in said spring;
• means indicating a predetermined position of said output shaft relative said valve shaft, indicating a predetermined amount of stored energy in said spring;
• means responsive to said indicating means for signaling and reversing said drive motor;
• a latch fixed to said reaction member other end responsive to said signal means for providing a releasable mechanical connection between said valve shaft and reaction member, thereby driving said shaft through said latch, providing bidirectional rotation over a predetermined amount of rotation;
• wherein, on loss of drive motor power and/or receipt of a predetermined signal, said latch releases the connection between said reaction member and valve shafts, and the stored energy in said spring turns said valve shaft relative to said reaction member and output shaft returning said valve shaft to a predetermined position.