Bleed valve for bleeding fluid from a hydraulic circuit

A hydraulic circuit for use in aircraft brake systems, the hydraulic circuit containing fluid under pressure and being operable in an inactive mode and an active mode, the fluid pressure in the hydraulic circuit being less than about 500 psi in the inactive mode and being substantially increased above 500 psi in the active mode, the hydraulic circuit comprising:

• a fluid line for directing fluid under pressure through the circuit, the fluid line having an opening therein for exhausting fluid from the fluid line;
• and
• a bleed valve adapted for connection to the fluid line in said opening for bleeding fluid from the fluid line via the opening, the bleed valve comprising
• a valve body having a valve passage therethrough adapted for fluid communication with the fluid line;
• a valve seat on the valve body;
• a sealing assembly comprising a valve stem disposed in the valve passage, a valve closure connected to the valve stem adapted for sealing engagement with the valve seat, and a push button connected to an outer end of the valve stem opposite the valve closure, the sealing assembly being moveable along a longitudinal axis of the valve passage between a closed sealing position in which the valve closure sealingly engages the valve seat to block fluid flow through the valve passage and an open position in which the valve closure is spaced from the valve seat to permit fluid flow through the valve passage, the push button projecting out from the valve body so that it is accessible for manually moving the sealing assembly to its open position;
• the valve closure having an end surface adapted for exposure to the pressurized fluid in the fluid line whereby the pressurized fluid acts against the valve closure end surface to urge the sealing assembly toward its closed position, the amount of force needed for moving the sealing assembly to its open position being greater than the biasing force of the fluid pressure;
• the end surface of the valve closure being sized so that in the inactive mode of the hydraulic circuit the biasing force of the fluid pressure provides low resistance against manual movement of the sealing assembly to its open position, and in the active mode of the hydraulic circuit the biasing force of the fluid pressure is substantially increased to provide substantial resistance against manual movement of the sealing assembly to its open position whereby the substantial resistance against manual movement indicates that the hydraulic circuit is in its active mode.

A bleed valve for bleeding fluid from a hydraulic circuit, the hydraulic circuit containing fluid under pressure and being operable in an inactive mode and an active mode, the fluid pressure in the hydraulic circuit being substantially increased in the active mode, the valve comprising:

• a valve body having a valve passage therethrough adapted for fluid communication with the hydraulic circuit;
• a valve seat on the valve body;
• a sealing assembly comprising a valve stem disposed in the valve passage, a valve closure connected to the valve stem adapted for sealing engagement with the valve seat, and a push button connected to an outer end of the valve stem opposite the valve closure, the sealing assembly being moveable along a longitudinal axis of the valve passage between a closed sealing position in which the valve closure sealingly engages the valve seat to block fluid flow through the valve passage and an open position in which the valve closure is spaced from the valve seat to permit fluid flow through the valve passage, the push button projecting out from the valve body so that it is accessible for manually moving the sealing assembly to its open position;
• the valve closure having an end surface adapted for exposure to the pressurized fluid of the hydraulic circuit whereby the pressurized fluid acts against the valve closure end surface to urge the sealing assembly toward its closed position, the amount of force needed for moving the sealing assembly to its open position being greater than the biasing force of the fluid pressure;
• the end surface of the valve closure being sized so that in the inactive mode of the hydraulic circuit the biasing force of the fluid pressure provides low resistance of not more than about 20 lbs. against manual movement of the sealing assembly to its open position, and in the active mode of the hydraulic circuit the biasing force of the fluid pressure is substantially increased to provide substantial resistance of at least about 50 lbs. against manual movement of the sealing assembly to its open position whereby the substantial resistance against manual movement indicates that the hydraulic circuit is in its active mode.