Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
2000-02-10
2001-05-08
Lee, Kevin (Department: 3754)
Fluid handling
Systems
Multi-way valve unit
C137S550000, C251S030030, C251S030050
Reexamination Certificate
active
06227247
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to gas valves and in particular to proportionally controlled gas thruster valves.
BACKGROUND OF THE INVENTION
Rockets and missiles are often guided by hot gas thruster valves that expel hot gas generated by the combusting of a solid propellant. Because of the difficulty associated with controlling and containing the hot gas, these valves are generally configured as on/off valve or pulse width modulated valves. A disadvantage to these types of valves is that their abrupt movement, on and off, can cause undesirable vibration and jitter in the vehicle and/or in the vehicle's guidance system. Another disadvantage is that these valves either provide maximum thrust or zero thrust and do not have the capability of providing a thrust level in between. In addition, the pressure of the solid propellant gas generator is dependent upon the exhaust area of these valves, and is thus subject to the ripple and uncertainty of pressure level which results. A system of proportional valves can provide trimming of the exhaust area, which in turn allows pressure control of the solid propellant motor. This feature can be exploited to also provide mission extension by selectively effecting high and low pressure, or high and low flow, segments of the overall mission. This leads to longer range and higher efficiency of the rocket or missile. On/off valves lack this capacity.
Accordingly, a need exists for a hot gas thruster valve that can operate smoothly and also provide intermediate thrust levels and solid propellant gas generator pressure control.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a position driven proportionally controlled thruster valve capable of providing intermediate levels of thrust as a function of a position input to the valve.
The present invention accomplishes this object by providing a thruster valve having a thrust nozzle and a piston slideably mounted in the valve. The piston be positionable to close and open the thrust nozzle. A front annulus surrounding the piston receives a hot gas at a pressure Ps. Passages flow a portion of this gas to an intermediate annulus at a pressure Pf and to a back chamber at a pressure Pa. Both the intermediate annulus and the back chamber have a nozzle and corresponding metering slot configured so that in the steady state condition the sum of their flow areas is a constant. A flapper is disposed between those nozzles. Movement of the flapper changes the flow area of the nozzles which changes the pressure differential between Pf and Pa causing the piston to move. As the piston moves the flow areas of the metering slots respectively change. When the system returns to the steady state condition, the piston stops moving.
Thus by changing the position of the flapper, the piston can be moved continuously from a closed position to an open position thus eliminating the abrupt movements of the prior art on/off valves and providing proportional control of the thrust produced by the thrust nozzle.
These and other objects, features and advantages of the present invention, are specifically set forth in, or will become apparent from, the following detailed description of a preferred embodiment of the invention when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 3326088 (1967-06-01), Hayner et al.
patent: 3910314 (1975-10-01), Nicholson
patent: 4922963 (1990-05-01), Robinson
patent: 5117868 (1992-06-01), Wagner
patent: 5240041 (1993-08-01), Garnjost
patent: 5697401 (1997-12-01), Shinoda et al.
patent: 5979862 (1999-11-01), Wölfges
Hydraulic Feedback Loop Eliminates Valve's Electronics, “Design Applications,” Charles J. Murray (Dec. 7, 1992).
Honeywell International
Lee Kevin
Newburry, Esq. Keith
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