Patent ID: 8469052

Claim:
A control valve comprising: a valve housing having an inlet side ( 17 ) and an outlet side ( 18 ), an amount control arrangement having an adjustable basic setting and a flow opening reducing arrangement, a pressure maintaining arrangement mounted in the valve housing for maintaining a constant differential pressure between an inlet side and an outlet side of said amount control arrangement, said pressure maintaining arrangement including a rolling diaphragm ( 5 ) and a throttle member ( 6 ) which sets itself in a balance between an inlet pressure on the one hand and an outlet pressure as well as a spring force on the other hand, respectively, the flow opening reducing arrangement activated via a spindle ( 10 ) connectable to an actuator, wherein amount control is established by relative rotation between of an inner cylinder shell ( 2 ) relative to an outer cylinder shell ( 3 ), the pair of cylinder shells disposed adjacent to each other, and having corresponding faces ( 2 a , 3 a ) disposed adjacent to each other, the faces being rotatably movable relative to each other, each face having a cooperating recess with the cooperating recesses movable into and out of alignment, the cooperating recesses together forming an orifice defining an unblocked area for flow to pass therethrough, rotatably moving the recesses relative to each other adjusting a size of the unblocked area for permitting control of an amount of flow therethrough, and wherein a reduction of flow is established by axial displacement of the pair of cylinder shells ( 2 , 3 ) within a seat hole ( 8 ), a reduction of the unblocked area taking place as the cooperating recesses of the pair of cylinder shells move into and out of the seat hole, thereby covering or uncovering the orifice formed by the cooperating recesses for reducing a flow therethrough.