Variable flow rate valve system

A valve system comprising:

• a valve chamber with an inlet and an outlet;
• a diaphragm dividing the valve chamber into a control chamber and a flow chamber connected with the inlet;
• a valve seat arranged in the flow chamber on a side of the outlet;
• a generally cylindrical valve body connected with the diaphragm and cooperating with the valve seat to modulate a flow from the inlet to the outlet and through the flow chamber,
• the valve body having two opposed end faces and a peripheral wall extending between the two opposed end faces, at least one inwardly extending recess being formed in the peripheral wall, and a bore extending from one of said end faces and opening into the at least one inwardly extending recess,
• wherein the at least one inwardly extending recess is generally wedge-shaped and extends transversely to an axis of the cylindrical valve body,
• wherein the at least one inwardly extending recess is defined by surfaces composed of surface sections having different angles of inclination in relation to the axis of the cylindrical valve body, and
• wherein at the end face comprising the bore, cylindrical geometry of the valve member is maintained over a full periphery, at least in a partial area;
• a first pilot valve located in a first bypass that extends between the outlet and the control chamber;
• a second pilot valve located in a second bypass that extends between the inlet and the control chamber;
• and
• a control unit for controlling the first and second pilot valves to selectively open or close the first and second bypasses thereby varying the flow through the flow chamber between a fully open and a fully closed condition.