1. Field of the Invention
This invention relates generally to rotary actuator devices for converting reciprocable motion to rotary motion.
2. Description of the Prior Art
Rotary actuators are commonly provided for converting linear movement to rotary movement, and are commonly used for opening and closing butterfly valves used in chemical processes and in water treatment facilities. Such rotary actuators have commonly employed a rack and pinion assembly for converting linear to rotary movement, the rack being actuated by a solenoid or a fluid power cylinder. Solenoid operated rotary actuators require appreciable current, sometimes over sustained periods of time, while fluid power cylinder operated rotary actuators involve the usual seal problems and close tolerances in machining the cylinder. It is therefore desirable to provide a fluid power operated type of rotary actuator employing a bellows for providing the operating force rather than the usual cylinder and piston.