Power plants – Reaction motor – Method of operation
Reexamination Certificate
2000-08-16
2001-05-22
Freay, Charles G. (Department: 3746)
Power plants
Reaction motor
Method of operation
C060S233000, C060S242000, C239S265190
Reexamination Certificate
active
06233919
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 valves 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 hot gas is dependent upon the exhaust area of these valves, and is thus subject to the ripple creating an uncertainty in pressure level. 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 force driven proportionally controlled thruster valve capable of providing intermediate levels of thrust as a function of a force input into the valve.
Another object of the present invention is to provide a method for continuously controlling the output of a thruster valve.
The present invention accomplishes these objects by providing a thruster valve having an inlet passage receiving a flow of propulsive gas and a thrust nozzle for generating thrust by expelling the gas. A poppet piston slideably mounted in a sleeve is disposed between the inlet passage and the thrust nozzle so as to control the flow of gas therebetween. Behind the piston is an actuator chamber. A change in the difference between the pressure in the thrust nozzle, the pressure in the inlet annulus, and the pressure in the actuator chamber causes the piston to move. This change is brought about by a change in a force balance on a flapper pivotally mounted in a flapper chamber in the valve. The force balance comprises a force input from a solenoid onto the flapper counterbalanced by the spring force of a resilient member, a nozzle pressure force and an actuation pressure force. Actuation pressure is set by a variable inlet restriction, effected by piston motion, and a variable outlet restriction, effected by flapper motion. Importantly, there is a known relationship between the input force and thrust out the thrust nozzle. When a change in thrust is required, the force input moves the flapper changing the pressure ratio across the piston which causes the piston to move. Because this pressure ratio is tied to the thrust level, once the piston reaches the position that results in the desired thrust, the force balance will be restored on the flapper and the piston will stop moving.
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: 3330114 (1967-07-01), McQueen
patent: 3848806 (1974-11-01), Samuelson et al.
patent: 3910314 (1975-10-01), Nicholson
patent: 4826104 (1989-05-01), Bennet et al.
patent: 4922963 (1990-05-01), Robinson
patent: 5117868 (1992-06-01), Wagner
patent: 5240041 (1993-08-01), Garnjost
Design Applications:Hydraulic Feedback Loop Eliminates Valve's Electronics, Charles J. Murray, (Design News Dec. 7, 1992).
Abel Stephen G.
Hopper Douglas T.
Pepe Michael A.
Ryan William F.
Silk Joseph P.
Freay Charles G.
Honeywell International , Inc.
Newburry, Esq. Keith
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