Two stage gas pilot valve controlling gas flow to a reaction jet nozzle

A reaction jet for a maneuvering aerospace vehicle comprising:

• a pyrotechnic gas generator for providing a source of pressurized gas;
• a nozzle for directing said pressurized gas, said nozzle comprising a primary valve regulating a flow of gas through said nozzle, said primary valve operatively coupled to a control chamber;
• a pilot valve for selectively supplying said pressurized gas to and venting pressurized gas from said control chamber, the pilot valve comprising:
• a first stage valve comprising a first pressure inlet, a first service port and a first exhaust outlet, said first stage valve further comprising a first stage valve member moveable between a first position and a second position, the first position allowing fluid communication between said first pressure inlet and said first service port, the second position allowing fluid communication between said first service port and said first exhaust outlet;
• a second stage valve comprising a second stage valve chamber, a second pressure inlet, a second service port and a second exhaust outlet, said second stage valve further comprising a second stage valve member disposed within said second stage valve chamber and moveable between an inlet position and an exhaust position, the inlet position allowing fluid communication between said second pressure inlet and said second service port, the exhaust position allowing fluid communication between said second service port and said second exhaust outlet, said second stage valve member being responsive to pressure in the first service port to move said second stage valve member;
• and
• a valve actuator operatively coupled to said second stage valve member, said valve actuator comprising a moveable actuating member and an actuator chamber, said moveable actuating member being operatively coupled to said actuator chamber and said actuator chamber being in fluid communication with said first service port, said moveable actuating member being responsive to rising pressure in said actuator chamber to move said second stage valve member from the inlet position to the exhaust position and being responsive to falling pressure in said actuator chamber to permit said second stage valve member to move from the exhaust position to the inlet position.

A reaction jet for a maneuvering aerospace vehicle comprising:

• a pyrotechnic gas generator for providing a source of pressurized gas;
• a nozzle for directing said pressurized gas, said nozzle comprising a primary valve regulating a flow of gas through said nozzle, said primary valve operatively coupled to a control chamber;
• a pilot valve for selectively supplying said pressurized gas to and venting pressurized gas from said control chamber, the pilot valve comprising:
• a first stage valve comprising a first pressure inlet, a first service port and a first exhaust outlet, said first stage valve further comprising a first stage valve member moveable between a first position and a second position, the first position allowing fluid communication between said first pressure inlet and said first service port, the second position allowing fluid communication between said first service port and said first exhaust outlet;
• a second stage valve comprising a second stage valve chamber, a second pressure inlet, a second service port and a second exhaust outlet, said second stage valve further comprising a second stage valve member disposed within said second stage valve chamber and moveable between an inlet position and an exhaust position, the inlet position allowing fluid communication between said second pressure inlet and said second service port, the exhaust position allowing fluid communication between said second service port and said second exhaust outlet, said second stage valve member being responsive to pressure in the first service port to move said second stage valve member;
• a valve actuator operatively coupled to said second stage valve member, said valve actuator comprising a moveable actuating member and an actuator chamber, said moveable actuating member being operatively coupled to said actuator chamber and said actuator chamber being in fluid communication with said first service port, said moveable actuating member being responsive to rising pressure in said actuator chamber to move said second stage valve member from the inlet position to the exhaust position and being responsive to falling pressure in said actuator chamber to permit said second stage valve member to move from the exhaust position to the inlet position, said moveable actuating member comprises a piston disposed in said actuator chamber;
• said piston having a surface with a first area exposed to pressure in said actuator chamber;
• and said second pressure inlet having a valve seat with a cross sectional area less than said first area such that when equal pressure is in said actuator chamber and said second pressure inlet, a force unbalance causes said valve member to be seated against said valve seat.

A method of controlling a reaction jet comprising a nozzle and a primary valve having a primary valve member moveable between an open and a closed position for regulating a flow of gases through the nozzle, the method comprising:

• initiating a pyrotechnic gas generator to provide a source of pressurized gas;
• introducing a first portion of the pressurized gas into a first stage valve having a first stage valve chamber;
• introducing a second portion of the pressurized gas into a second stage valve having a second stage valve chamber;
• introducing a third portion of the pressurized gas into the primary valve;
• moving a valve member of the first stage valve into a first position closing a port theretofore communicating the first portion of pressurized gas to a second stage control chamber and opening a vent from the second stage control chamber to an exhaust port thereby permitting the second stage control chamber to depressurize;
• in response to the depressurization of the second stage control chamber, moving a valve member of said second stage valve into an inlet position to direct the second flow of pressurized gas into a primary control chamber to cause the primary control chamber to pressurize;
• in response to the pressurization of the primary control chamber, moving the primary valve member into a closed position, thereby halting flow of the third portion of pressurized gases through the nozzle.