Valve

Claim 2

A valve comprising a housing, a first bore, an open center main valve reciprocably received in said first bore, a second bore in said housing, a pilot valve reciprocably received in said second bore, a first fluid circuit comprising first inlet and outlet means communicating said first bore with first fluid pressure source means and a reservoir respectively, cylinder inlet-outlet ports in said first bore, a second fluid circuit comprising second inlet and outlet means communicating said second bore with a second fluid pressure source and reservoir respectively, a motor chamber at each end of said main valve, first passageway means communicating said second fluid pressure source to one of said chambers, and second passageway means communicating said other chamber to said second bore, said pilot valve extending across said second passageway means, actuating means for shifting said pilot valve to selectively communicate said other chamber to said second fluid pressure source or said second reservoir through said second passageway means, whereby a fluid pressure differential between said chambers causes said main valve to shift, said actuating means responsive to at least one of a plurality of input signals, first connecting means between said actuating means and said pilot valve, second connecting means interconnecting said actuating means and said main valve, whereby movement of said actuating means in response to an input signal moves said pilot valve to determine a movement of said main valve producing a force tending to shift actuating means in opposition to said input signal.

Claim 3

The valve of claim 1 wherein the pressure level of said second fluid pressure source is lower than that of said first fluid pressure source.

Claim 4

The valve of claim 1 wherein said main valve is a spool valve.

Claim 5

The valve of claim 1 wherein said actuating means is an electric torque motor.

Claim 6

The valve of claim 4 and including a manual override means for actuating said pilot valve.

Claim 7

A valve comprising a housing, a first bore, an open center main valve reciprocably received in said first bore, a second bore in said housing, a pilot valve reciprocably received in said second bore, a first fluid circuit comprising first inlet and outlet means communicating said first bore with first fluid pressure source means and a reservoir respectively, cylinder inlet-outlet ports in said first bore, a second fluid circuit comprising second inlet and outlet means communicating said second bore with a second fluid pressure source and reservoir respectively, a motor chamber at each end of said main valve, first passageway means communicating said second fluid pressure source to one of said chambers, and second passageway means communicating said other chamber to said second bore, said pilot valve extending across said second passageway means, actuating means for shifting said pilot valve to selectively communicate said other chamber to said second fluid pressure source or said second reservoir through said second passageway means, whereby a fluid pressure differential between said chambers causes said main valve to shift, said actuating means comprising a torque motor means having a pivoted armature supported with respect to the valve housing, first connecting means directly connecting said armature to said pilot valve, second connecting means having a lost-motion action connecting said armature to said main valve, electrical actuating means to impress an electrical signal upon the torque motor means and non-electrical actuating means connected to said armature, whereby displacement of the armature from a neutral position of zero torque by a net torque exerted on the armature by one or more of said electrical actuating means initiates through movement of said pilot valve a responsive movement of said main valve restoRing the armature to a neutral position, thereby affecting the direction and magnitude of flow through said inlet-outlet ports.

Claim 8

A valve comprising a housing, a first bore, an open center main valve reciprocably received in said first bore, a second bore in said housing, a pilot valve reciprocably received in said second bore, a first fluid circuit comprising first inlet and outlet means communicating said first bore with first fluid pressure source means and a reservoir respectively, cylinder inlet-outlet ports in said first bore, a second fluid circuit comprising second inlet and outlet means communicating said second bore with a second fluid pressure source and reservoir respectively, a motor chamber at each end of said main valve, first passageway means communicating said second fluid pressure source to one of said chambers, and second passageway means communicating said other chamber to said second bore, said pilot valve extending across said second passageway means, actuating means for shifting said pilot valve to selectively communicate said other chamber to said second fluid pressure source or said second reservoir through said second passageway means, whereby a fluid pressure differential between said chambers causes said main valve to shift, said actuating means comprising a torque motor means having a pivoted armature supported with respect to the valve housing, first connecting means directly connecting said armature to said pilot valve, second connecting means having a lost-motion action connecting said armature to said main valve, electrical actuating means to impress an electrical signal upon the torque motor means and non-electrical actuating means connected to said armature, whereby displacement of the armature from a neutral position of zero torque by a net torque exerted on the armature by one or more of said electrical actuating means initiates through movement of said pilot valve a responsive movement of said main valve restoRing the armature to a neutral position, thereby affecting the direction and magnitude of flow through said inlet-outlet ports.