Valve with controlled flow characteristics

Claim 1

A flow control valve comprising a casing having a fluid inlet and a fluid outlet, valve means movable in said casing between said inlet and said outlet, said valve means including a cylinder having a closed end and an open end and having apertures formed therein communicating with said open end to define a fluid flow path therethrough, said apertures being arranged in a series of circumferential rows wherein the cross-sectional areas of each of the said apertures in a given row are equal, the total crosssectional area of the said apertures in a given row being progressively greater than the total cross-sectional area of the said apertures in the preceding rows, said cylinder including a peripheral lip extending radially from said closed end, a shoulder formed internally of said casing providing a seat for said lip, sealing means provided between said cylinder and said casing, the axial movement of said valve means serving to progressively and cumulatively expose each of said rows of apertures to the flow of fluid thereby varying the flow conducting area through said valve, and wherein the locus of all the apertures in a single row defines a plane that is inclined to the axis of movement of said valve in said casing such that the apertures in a single row will be sequentially exposed and the exposure of the last aperture in a particular row will overlap the exposure of the first aperture in the next row whereby a smooth characteristic flow pattern is achieved.