| 摘要 |
<p>The present invention is a bi-directional valve actuator with a ratchet mechanism for use in combination with a control valve which includes a stem which, when turned, adjusts the flow through the control valve. The bi-directional valve actuator includes a frame which is mechanically coupled to the control valve adjacent to the outer end of the stem of the control valve. The valve actuator also includes a shaft which is disposed within the frame and which is rotatably coupled thereto with the shaft being mechanicially coupled to the stem of the control valve so it can turn the stem thereof, a first ratchet wheel and a second ratchet wheel. Each ratchet wheel is coaxially aligned with the shaft and is fixedly coupled thereto. The valve actuator further includes a pair of pawls, each of which is coupled to one of the ratchet wheels so that when the pawl is driven forward it becomes coupled to the teeth of one of the ratchet wheels and when the pawl is pulled backward it becomes uncoupled from the teeth of one of the ratchet wheels. Each pawl is mechanically coupled to and driven forward by a hydraulic cylinder with a piston, which is fixedly coupled to the pawl and it is also mechanically coupled to and driven backward by a pair of springs mechanically coupled to the frame. The pawl is coupled to the wheel of the ratchet wheel by a collar which is disposed about the peripheral edge of the ratchet wheel and which has a slot and a radially disposed hole with a pin and spring assembly therein. The pin and spring assembly is mechanically coupled to the pawl by a pin.</p> |
