Proportional control valve

Abstract

A proportional control valve is described having a housing with a bore formed therein. The first valve contains passages therein which communicate between the fluid inlet and the fluid outlet. Also positioned within the bore is a second valve which is aligned with one of the passages formed in the first valve. As the second valve is moved to a closed position, fluid flow through the passage is cut off and as the second valve is opened, fluid flow through the passage is permitted. A sleeve is also positioned within the bore which is constructed of a non-magnetic section sandwiched between two magnetic end sections. The sleeve contacts the first valve and is formed such that the non-magnetic section surrounds a portion of the second valve. The proportional control valve also contains an electromagnet for linearly moving the second valve in response to an input signal. Movement of the second valve creates a fluid flow path across the first valve and establishes a pressure differential which causes the first valve to follow the movement of the second valve. Likewise, movement of the first valve causes the sleeve to move in a like direction thereby providing an essentially constant air gap between the upper surface of the second valve and the end of the sleeve. This constant air gap is beneficial in that it permits the stroke of the first valve to be increased without increasing the power input to the electromagnet.

Dependencies are inferred from the claim text.