초록 ▼

A multi-port, self-regulating, proportional control valve preferably uses a load output feedback system to produce working fluid load output pressures that are proportional to pilot control fluid pressures. In some embodiments, the control valve is programmable and capable of different load output p

A multi-port, self-regulating, proportional control valve preferably uses a load output feedback system to produce working fluid load output pressures that are proportional to pilot control fluid pressures. In some embodiments, the control valve is programmable and capable of different load output pressures selected either prior to, or during, operation. The control valve apparatus according to the present invention is capable of a center-off or neutral condition that requires substantially no pilot control flow when there in no control valve output flow.

대표청구항 ▼

In a pneumatic fluid control valve apparatus having a working fluid inlet connectable to a source of pressurized pneumatic working fluid, a pair of working fluid load outlets, a movable valve member, and a pilot operator for selectively applying a pneumatic control fluid pressure to the movable valv

In a pneumatic fluid control valve apparatus having a working fluid inlet connectable to a source of pressurized pneumatic working fluid, a pair of working fluid load outlets, a movable valve member, and a pilot operator for selectively applying a pneumatic control fluid pressure to the movable valve member in order to communicate a selected one of the load outlets with the working fluid inlet to produce load outlet pressures dependent upon the position of the movable valve member, the improvement wherein the pilot operator includes a pair of control pistons interconnected with opposite sides of the movable valve member, the pilot operator being selectively operable to apply control fluid pressure to a selected one of said control pistons and to exhaust control fluid pressure from the other of said control pistons in order to cause selective movement of the movable valve member in either of opposite directions, said control valve apparatus including self-regulation means for maintaining the load outlet pressure proportional to the control fluid pressure, said self-regulation means including portions on opposite sides of the movable valve member and feedback means in fluid communication with said valve member portions for applying load outlet pressure from said selected load outlet to one of said valve member portions in order to tend to urge said movable valve member in a direction opposing movement of the movable valve member in a direction that communicates the working fluid inlet with said selected load outlet, the area of each of said control pistons being greater than the area of each of said valve member portions, the load outlet pressure at said selected load outlet being proportional to the control fluid pressure applied to said one of said control pistons in the same ratio as the ratio of the area of said one of said control pistons to the area of said one of said valve member portions, the pilot operator further including means for selectively applying equal control fluid pressures to both of said control pistons simultaneously in order to maintain the movable valve member in a center-off position with substantially no working fluid flow and substantially no control fluid flow, said self-regulation means also tending to maintain the movable valve member in said center-off position in the event of undesired movement from said center-off position.