Patent ID: 7357151

Claim:
A pressure-actuated valve comprising: (a) a valve body with an inlet orifice and an outlet orifice, and a first cavity and a second cavity disposed between said inlet and outlet orifices, said two cavities being in communication with each other through a first passageway and a second passageway, said inlet orifice providing communication between said second cavity and outside the valve body and said outlet orifice providing communication between said first cavity and outside the valve body; (b) a plunger movably disposed in said second cavity and extending through said first passageway into said first cavity, said plunger containing a poppet disposed in a chamber within said plunger, said poppet movably attached to the plunger by a first spring, said plunger chamber having an opening of smaller dimensions than said poppet; (c) a second spring disposed under compression in said first cavity and in contact with said plunger such that motion of the plunger further compresses or relaxes the second spring; (d) a valve seat with a central seat orifice, mounted within said valve body and disposed where said second passageway enters said second cavity, to sealingly engage said poppet through the opening in the plunger chamber, thereby closing said second passageway and placing the valve in its “off” position, said seat orifice being of smaller area than said first passageway's cross section; and (e) a seal to prevent fluid passage through said first passageway between said two cavities; wherein, in operation, said two cavities are filled with fluid (possibly containing small solids) at different pressures, the fluid in the second cavity being at higher and increasing pressure, and the poppet remains in contact with the valve seat due both to the pressure differential and force from the first spring under compression until the fluid pressure in the second cavity exceeds that in the first cavity sufficiently to cause the plunger to move toward the first cavity against resistance due to compression of the second spring, eventually bringing the plunger chamber opening into contact with the poppet pulling the poppet off the valve seat and thus placing the valve in its “on” position and allowing the fluid to flow out the outlet until the pressure differential reverses sufficiently to permit the compressed second spring to move the poppet back into engagement with the seat halting the flow, said first spring being sized to be under compression at all times.