Fluid flow switch

Abstract

A flow switch is disclosed comprising a body member having a fluid inlet and a fluid outlet defined therein. An outer core tube is disposed within the body member and has a first and a second end. An inner core tube is disposed coaxial to and within the outer core tube and has a first and a second end with the first ends of the inner and outer core tubes being disposed adjacent the fluid inlet. One of the inner and outer core tubes being in fluid communication with the fluid inlet. The body member defines a body flow path between the outer core tube and the body member and in fluid communication with the fluid outlet. A first aperture is defined by the inner core tube and a second aperture is defined by the outer core tube. Securing means secures one of the core tubes to be non-rotatable relative to the body member. The other of the core tubes is rotatable relative to the body member enabling the first aperture to register with the second aperture for defining a first orifice of variable size to provide a variable flow path from the fluid inlet to the body flow path and to the fluid outlet in accordance with the relative rotational position between the inner and outer core tubes. A cylindrical chamber is defined by the rotatable core tube. A piston is slidably disposed in the cylindrical chamber for movement in accordance with the fluid flow through the fluid inlet. A switch is disposed proximate the piston for providing a switching output in response to the fluid flow through the fluid inlet exceeding a preselected level.