초록 ▼

A normally closed fluid switching logic element has a plurality of radial ports to a first chamber. A poppet, connected to a piston within the element, moves between an open position off its poppet seat and a closed position. In the open position another port is provided to the first chamber permitt

A normally closed fluid switching logic element has a plurality of radial ports to a first chamber. A poppet, connected to a piston within the element, moves between an open position off its poppet seat and a closed position. In the open position another port is provided to the first chamber permitting fluid flow. The poppet is biased to the closed position by a spring, but also by fluid pressure at either or both ports. The poppet may be displaced only by pressure in a second chamber behind the piston. In one configuration this opening pressure is provided from an external source. In other configurations, the opening pressure is derived from the first chamber, from the pressure outside the poppet and from either of these.

대표청구항 ▼

A normally closed fluid switching logic element having open and closed positions for controlling flow of fluid therethrough, said logic element requiring the presence of a pilot pressure in a pilot pressure chamber for fluid flow and said logic element having a body adapted for receiving different p

A normally closed fluid switching logic element having open and closed positions for controlling flow of fluid therethrough, said logic element requiring the presence of a pilot pressure in a pilot pressure chamber for fluid flow and said logic element having a body adapted for receiving different piston assemblies for providing the pilot pressure by different modes, comprising: a body having a longitudinally extending bore therein, said bore open at one end and closed at the other end; a poppet seat at said open end of said bore; a shoulder extending radially inwardly from said body into said bore; a piston assembly having: a piston slideably and sealingly supported in said bore; said piston having first and second ends; a stem extending from said second end of said piston to a distal end; said stem having a poppet disposed at said distal end; said poppet having a closed position when it is positioned against said poppet seat, said closed position defining said logic element closed position; said poppet having an open position when it is displaced from said poppet seat, said open position defining said logic element open position; a spring having one end positioned against said second end of said piston; said spring having a second end positioned against said shoulder, whereby said spring biases said poppet against said poppet seat; a first primary fluid port formed by said poppet and said poppet seat when said poppet is displaced from said poppet seat; a first variable volume chamber defined by said second end of said piston, said body, said stem and said poppet; a second primary fluid port extending from said first variable volume chamber through said body; a second variable volume pilot pressure chamber defined by said closed end of said bore, said body and said first end of said piston; and a third pilot pressure regulating fluid port extending from said second variable volume pilot pressure chamber through said body for regulating the pilot pressure in said second variable volume pilot pressure chamber.