Valve arrangement for unloading liquid flow at a non-return valve

Claim 1

A minimum flow valve device which can be used in a fluid line connected to an operating centrifugal pump to supply cooling liquid thereto even when the fluid flow through the line is stopped, said valve device comprising a housing which provides a liquid passageway therethrough, said liquid passageway having an inlet end and an outlet end and defining a center line therethrough, an elongated guide element fixedly positioned in said liquid passageway in said housing so as to be aligned with said center line, said guide element including a sleeve portion nearest said inlet end of said liquid passageway and an end portion nearest said outlet end of said liquid passageway, said sleeve portion and said end portion defining an internal chamber which is open towards said inlet end and closed towards said outlet end of said liquid passageway; said sleeve portion having an outer surface and an inner sliding surface, an annular groove which is open towards said internal chamber and a discharge orifice which extends from said annular groove to said outer surface, an unloading pipe which extends through said housing and connects with the outer surface of said sleeve portion of said guide element so as to communicate with said discharge orifice, a non-return valve element which is movably positioned in said liquid passageway between said guide element and the inlet end of said liquid passageway, and a valve sleeve member which is connected to said non-return valve element and is movable within said internal chamber of said guide element, said valve sleeve providing an internal channel therein and having an outer sliding surface which is slidingly movable with respect to the inner sliding surface of the sleeve portion of said guide element and a plurality of orifices which extend therethrough in a common radial place; said non-return valve element and said valve sleeve being jointly movable back and forth from a first position where they block liquid flow through said liquid passageway to a second position where they allow liquid flow through said liquid passageway, said orifices in said valve sleeve being in communication with said annular groove in the sleeve portion of said guide element only when said non-return valve element and said valve sleeve member are in their first position, thus enabling liquid to flow from said inlet end of said liquid passageway, through said interior channel, through said discharge orifice and through said unloading pipe.