Patent ID: 8172197

Claim:
Valve apparatus, comprising: a pneumatic valve comprising a piston that is slidably movable along a longitudinal axis in a piston chamber which has an upper chamber portion above the piston and a lower chamber portion below the piston, wherein the piston has: (i) a peripheral surface that is slidably sealed to an inside wall of the piston chamber, and (ii) a hub that is slidably sealed and movable longitudinally in relation to a boss in the upper chamber portion which has a duct that delivers pressurized pilot air to the piston, and (iii) a duct through the piston that connects the lower chamber portion in fluid flow relation to the duct in the boss; a main valve body portion with a main valve opening at a longitudinally spaced distance under the piston so that the piston is movable toward and away from the main valve opening; a main valve closure member positioned between the piston and the main valve opening, said main valve closure member being sized and shaped for closing the main valve opening and being movable toward and away from the main valve opening in response to movement of the piston toward and away from the main valve opening, wherein said movement of the main valve closure member toward the main valve opening is sufficient to close the main valve opening and said movement of the main valve closure member away from the main valve opening is sufficient to open the main valve opening; a pressurized pilot air inlet port that is connectable to a source of pressurized pilot air; and a solenoid pilot valve positioned between the pressurized pilot air inlet port and the boss, said solenoid pilot valve comprising: (i) a sleeve positioned between the pressurized pilot air inlet port and a spool, said spool having an outlet duct that is in fluid flow relation with the atmosphere and opens into the sleeve, and said spool having an intermediate duct that is in fluid flow relation with the duct in the boss and that opens into the sleeve; (ii) a wire coil around the sleeve that creates an electromagnetic field in axial alignment with the sleeve when an electric current flows through the coil; and (iii) an armature positioned slidably in the sleeve and that is responsive to the electromagnetic field for reciprocating movement back and forth between the pressurized pilot air inlet port and the spool, wherein said armature is configured to be a pilot air inlet closure member that closes the pressurized pilot air inlet when the armature is moved in one direction while the intermediate duct and the outlet duct are in fluid flow communication with each other to exhaust air from the piston to the atmosphere, and wherein said armature is configured to be an air outlet closure member that closes the air outlet duct when the armature is moved in the opposite direction while the pressurized pilot air inlet is open to force pressurized pilot air via the sleeve, the intermediate duct, the duct in the boss, and the duct in the piston into the lower chamber portion to move the piston.