Electro-proportional pressure control apparatus

In pressure-control apparatus for connection to and combination with a source of fluid pressure;

• power-valve means including an inlet port and an outlet port, a valve element having opposed control areas, a first fluid chamber communicating with one of said control areas and having means for connection to said source, a second fluid chamber communicating with the other of said control areas, said valve element being movable between open and closed positions responsive to a pressure-differential between said first and second chambers for delivering a control flow of fluid from the source and via said ports, means biasing said valve member in its valve-closing direction, and control means to modify the pressure difference between said chambers;
• said control means comprising a pilot valve having inlet and outlet ports, a first inlet-port connection for said pilot valve for connecting the same to the source and including a first orifice for drawing a control flow of pressure fluid, said pilot valve including a pilot-valve element with at least one control area, a pilot-valve fluid chamber communicating with said pilot-valve control area, chamber-connection means for connecting said pilot-valve chamber to the source whereby the pilot-valve chamber senses source pressure via the orifice of said pilot-valve chamber-connection means, a control connection from said pilot-valve inlet port to the second chamber of said power-valve means, means for biasing said pilot-valve member with a force in opposition to pressure in said pilot-valve chamber, and a second pilot-valve inlet-port connection including a biased check valve for connecting the pilot valve to the source in parallel with said first inlet-port connection, said check valve being biased to open at a predetermined pressure differential across said first pilot-valve inlet-port connection, whereby operation of said power-valve means is limited to the range protected by the bias setting of said check valve.

In a pressure-control apparatus for connection to and combination with a source of fluid pressure, a high-pressure control-function line for connection to the source, a reduced-pressure system line including pressure-reducing means for connection to the source, means including a restrictive orifice interconnecting said control-function line and said system line;

• a signal-pressure stage including a signal-pressure valve having an inlet port and flow-control valve means connecting said control-function line to said port so that a constant-flow condition may be established for said signal-pressure valve;
• a preamplifier stage comprising a pilot valve having inlet and outlet ports, a pilot-valve inlet-port connection including an orifice for connecting the same to said control-function line for drawing a control flow of pressure fluid, a pilot-valve element having opposed control areas and with first and second fluid chambers communicating with the respective control areas, a signal-pressure control connection from said signal-pressure port to one of said pilot-valve chambers, means connecting the other pilot-valve chamber to said system line, whereby said other pilot-valve chamber may sense system-line pressure;
• and a power stage comprising power-valve means having inlet and outlet ports, a power-valve element having opposed control areas and with first and second fluid chambers communicating with the respective control areas, means connecting one of said power-valve chambers to said control-function line, means connecting the other power-valve chamber to the inlet-port connection of said pilot valve, means connecting said system line to said power-valve inlet port, said power-valve element being movable between open and closed positions responsive to a pressure-differential between said power-valve chambers for delivering a control flow of fluid from said system line and via said power-valve ports, and means biasing said power-valve member in its valve-closing direction.

In a pressure-control apparatus for connection to and combination with a principal source of fluid pressure and for selective further connection to and combination with a supplementary source of fluid pressure at relatively elevated pressure and relatively low flow, a control-function line for connection to the supplementary source, a system-supply line for connection to the principal source, means including a restrictive orifice interconnecting said control-function line and said system-supply line;

• a signal-pressure stage including a signal-pressure valve having an inlet port and flow-control valve means connecting said control-function line to said port so that a constant-flow condition may be established for said signal-pressure valve;
• a preamplifier stage comprising a pilot valve having inlet and outlet ports, a pilot-valve inlet-port connection including an orifice for connecting the same to said control-function line for drawing a control flow of pressure fluid, a pilot-valve element having opposed control areas and with first and second fluid chambers communicating with the respective control areas, a signal-pressure control connection from said signal-pressure port to one of said pilot-valve chambers, means connecting the other pilot-valve chamber to said system-supply line, whereby said other pilot-valve chamber may sense system-supply line pressure;
• and a power stage comprising power-valve means having inlet and outlet ports, a power-valve element having opposed control areas and with first and second fluid chambers communicating with the respective control areas, means connecting one of said power-valve chambers to said control-function line, means connecting the other power-valve chamber to the inlet-port connection of said pilot valve, means connecting said system-supply line to said power-valve inlet port, said power-valve element being movable between open and closed positions responsive to a pressure-differential between said power-valve chambers for delivering a control flow of fluid from said system-supply line and via said power-valve ports, and means biasing said power-valve member in its valve-closing direction.

Electro-proportional relief-valve apparatus for connection to and combination with a system-supply line having means for connection to a source of fluid pressure;

• a signal-pressure stage including an electrically operated signal-pressure valve having an inlet port and flow-control valve means connecting said system-supply line to said port so that a constant-flow condition may be established for said signal-pressure valve;
• a preamplifier stage comprising a pilot valve having inlet and outlet ports, a pilot-valve inlet-port connection including an orifice for connecting the same to said system-supply line for drawing a control flow of pressure fluid, a pilot-valve element having opposed control areas and with first and second fluid chambers communicating with the respective control areas, a signal-pressure control connection from said signal-pressure port to one of said pilot-valve chambers, means connecting the other pilot-valve chamber to said system-supply line, whereby said other pilot-valve chamber may sense system-supply line pressure;
• and a power stage comprising power-valve means having inlet and outlet ports, a power-valve element having opposed control areas and with first and second fluid chambers communicating with the respective control areas, means connecting one of said power-valve chambers to said system-supply line, means connecting the other power-valve chamber to the inlet-port connection of said pilot valve, means connecting said system-supply line to said power-valve inlet port, said power-valve element being movable between open and closed positions responsive to a pressure-differential between said power-valve chambers for delivering a control flow of fluid from said system-supply line and via said power-valve ports, and means biasing said power-valve member in its valve-closing direction.

In pressure-control apparatus for connection to and combination with a source of fluid pressure;

• power-valve means including an inlet port and an outlet port, a valve element having opposed control areas, a first fluid chamber communicating with one of said control areas and having means for connection to said source, a second fluid chamber communicating with the other of said control areas, said valve element being movable between open and closed positions responsive to a pressure-differential between said first and second chambers for delivering a control flow of fluid from the source and via said ports, means biasing said valve member in its valve-closing direction, and control means to modify the pressure difference between said chambers;
• said control means comprising a pilot valve having inlet and outlet ports, an inlet-port connection for said pilot valve for connecting the same to the source and including a first orifice for drawing a control flow of pressure fluid, said pilot valve including a pilot-valve element with at least one control area, a pilot-valve fluid chamber communicating with said pilot-valve control area, chamber-connection means for connecting said pilot-valve chamber to the source and including an orifice whereby the pilot-valve chamber senses source pressure via the orifice of said pilot-valve chamber-connection means, a control connection from said pilot-valve inlet port to the second chamber of said power-valve means, said control connection including a restrictive orifice, means for biasing said pilot-valve member with a force in opposition to pressure in said pilot-valve chamber, and means including a compliant barrier to static flow effectively interconnecting said source and the second fluid chamber of said power-valve means on the power-valve side of the restrictive orifice of said control connection.

In pressure-control apparatus for connection to and combination with a source of fluid pressure;

• power-valve means including an inlet port and an outlet port, a valve element having opposed control areas, a first fluid chamber communicating with one of said control areas and having means for connection to said source, a second fluid chamber communicating with the other of said control areas, said valve element being movable between open and closed positions responsive to a pressure-differential between said first and second chambers for delivering a control flow of fluid from the source and via said ports, means biasing said valve member in its valve-closing direction, and control means to modify the pressure difference between said chambers;
• said control means comprising a pilot valve having inlet and outlet ports, an inlet-port connection for said pilot valve for connecting the same to the source and including a first orifice for drawing a control flow of pressure fluid, said pilot valve including a pilot-valve element with two opposed control areas, a first pilot-valve fluid chamber communicating with one of said pilot-valve control areas, chamber-connection means for connecting said first pilot-valve chamber to the source and including an orifice whereby the pilot-valve chamber senses source pressure via the orifice of said pilot-valve chamber-connection means, a control connection from said pilot-valve inlet port to the second chamber of said power-valve means, said control connection including a restrictive orifice, and means for loading said pilot-valve member with a force in opposition to pressure in said pilot-valve chamber, said last-mentioned means including a second pilot-valve fluid chamber communicating with the other of said pilot-valve control areas;
• a signal-pressure valve having an inlet port and means including a pressure-compensated flow-control valve for connecting said signal-pressure port to the source so that a constant-flow condition may be established for said signal-pressure valve, and a signal-pressure control connection from said signal-pressure port to said second pilot-valve fluid chamber, said flow-control valve including a movable flow-control member and associated porting;
• and means including a compliant barrier to static flow effectively inter-connecting said source via said flow-control porting and to the second fluid chamber of said power-valve means, said last-mentioned connection being normally open and responsive to movement of said flow-control member such that said last-mentioned connection is effectively closed upon approach to achievement of said constant-flow condition.