Wide range proportional flow control valve

摘要

A continuous flow type proportional flow control valve having a very wide controllable flow range and having a valve seat port design permitting a continuous, stable closed loop control to be achieved. The flow port design cooperates with a simple cylindrical flow passage of a movable valve element and provides the valve with a very wide flow control range and the ability to smoothly control the opening, modulation, and closing of the valve to eliminate undesirable hydraulic shock which is an undesirable characteristic of pulse operated flow control systems. The flow controlling seat has a flow controlling port therein that cooperates with the flow port of the closure to define an effective valve opening that is proportionally variable over a wide range of closure movement. The seat port is provided with an extremely narrow elongate slot section less than +E,fra 1/50+EE th of the maximum width of the aperture. The seat opening also defines a large final, generally circular orifice section having a radius comparable to the radius of the bore in the ball. Further, the seat opening is defined by a transition between the elongate narrow slot and final circular orifice section in the form of two diverging curves offering an exponential flow characteristic of the form K=Nx.