Fluid pressure amplifying unit

Claim 1

In a pressure-amplifying unit, a closed center crossover main valve assembly movable between the supply position and an exhaust position, a supply port for said main valve assembly, a working port connected to said supply port when said main valve assembly is in it supply position, an exhaust port for said main valve assembly, said working port being connected to said exhaust port when the main valve assembly is in its exhaust position, a supply valve disposed between said supply and working ports, resilient means urging said supply valve to its closed position, a piston for moving said main valve assembly to its supply position, an exhaust valve carried by an extension on said piston and disposed between said working and exhaust ports, said exhaust valve closing by engagement with said supply valve when said piston is extended, whereby it is assured that said working port is disconnected from said exhaust port before being connected To said supply port, resilient means for retracting said piston, means for supplying fluid pressure through an orifice to said piston, a bleed connection for said piston having a cross secton substantially larger than said orifice, whereby said piston will be effectively connected to exhaust a free floating diaphragm and a plate forming a flat low-pressure signal chamber with a relatively small volume, a pilot valve movable with said diaphragm and responsive to pressure in the diaphragm chamber to close said bleed connection, whereby pressure supplied to said piston through said orifice will cause said main valve assembly to move from its exhaust to its supply position, said main valve assembly comprising a valve body having a central bore, said supply valve being of rubberlike material coaxial with said piston and spring urged toward the piston, said supply port being connected to the portion of said bore containing said supply valve, an insert in said valve body bore having an annular seat engageable by said supply valve, said extension on said piston passing through said annular seat when said piston is actuated by fluid pressure, said exhaust valve comprising a central axial passage in said extension opening toward said supply valve member and engageable therewith when the piston is so moved to close said central passage, said working port being connected to a central bore in said insert through which said extension passes, whereby said central passage will be connected with said working port when said piston is retracted, a chamber surrounding said piston extension, a seal separating said last-mentioned chamber from said bore connected to the working port, and a radial passage in said piston extension connecting said axial passage to said last-mentioned chamber, said exhaust port being connected to said last-mentioned chamber, whereby said working port will be connected to said exhaust port when the piston is retracted.