Fluid handling – Line condition change responsive valves – With separate connected fluid reactor surface
Reexamination Certificate
1999-05-06
2001-02-06
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Line condition change responsive valves
With separate connected fluid reactor surface
C137S500000, C244S13500B
Reexamination Certificate
active
06182688
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an autonomous device for limiting the rate of flow of a fluid through a pipe, and to a fuel circuit for an aircraft comprising such a device.
2. Description of Related Art
It is often useful, in many applications, where fluid is flowing through a pipe, to be able to limit the rate of flow of this fluid to a pre-set value.
Devices are known that allow the flow rate of a fluid to be limited, but none of these can be used indiscriminately either with gases or with liquids. Furthermore, such known devices operate in one or other of the following modes:
either in controlled mode, therefore requiring at least one member for measuring physical magnitude (the voltage or current from a flow meter, pressure, in particular) which, associated via a control loop, allows a regulating member (shut-off valve for example) to be controlled;
or in uncontrolled mode, in which case the flow rate is limited by the appropriate dimensioning of limiter members placed directly in the pipe (orifice plate, nozzle, in particular), possibly associated with pressure-reducing devices.
In the case of the controlled mode, operation is not autonomous and remains subordinate to members for measuring a physical magnitude and for providing regulation, which are associated with appropriate processing logic and an external energy source.
In uncontrolled mode, operation is still dependent upon parameters that are liable to change, such as the pressure upstream of the device, for example, and the flow rate can be limited only for a clearly defined maximum upstream pressure.
Thus, none of the known devices can rid itself of all its dependencies on: the nature of the fluid (gaseous or liquid), known values of pressure levels, or an energy supply for powering the flow-limiter members (shut-off member or valve for example).
SUMMARY OF THE INVENTION
Although not exclusively, the present invention is particularly appropriate for limiting the rate of flow of fuel supplied by an aircraft to its engine(s), so as to avoid the phenomenon usually known by the name of “overthrust” that is liable to occur in the event of malfunctioning of the fuel flow regulating systems. This phenomenon, which may arise during the most tricky stages of the flight, particularly on landing (especially final approach and flare-out), may lead to a dangerous situation, as the limit of controllability of the aircraft may be reached.
The object of the present invention is to avoid these drawbacks.
To this end, the autonomous device for limiting the rate of flow of a fluid through a pipe, the flow rate of said fluid depending on the cross section for passage of said fluid in said pipe and on the difference between upstream and downstream pressures relative to said passage cross section, in the direction in which said fluid flows, is noteworthy, according to the invention, in that it comprises:
means of regulating said passage cross section;
deformable means, rigidly connected to said regulating means and subjected, on one side, to said upstream pressure and, on the other side, to said downstream pressure; and
means capable of defining, for a predetermined difference between upstream and downstream pressures, a position of equilibrium for said regulating means and said deformable means,
a variation in the difference between said upstream and downstream pressures leading to a deformation of said deformable means and to an accompanying movement of said regulating means to return the difference between said upstream and downstream pressures to the difference that corresponds to said position of equilibrium.
Thus, the device according to the invention is entirely autonomous without any external supply of energy, it can be used irrespective of the nature of the fluid flowing through the pipe on which it is mounted, and its operation depends only on the set, value of the difference between the upstream and downstream pressures, which value is kept constant between the upstream and downstream end of a clearly defined passage cross section.
As a preference, the means of regulating said passage cross section comprise, in a first chamber of a housing which is subdivided into two chamber parts connected by a first orifice, a shutter, the frustoconical surface of which has a configuration adapted to suit the surface facing it of the edge of said orifice, and said deformable means consist of a flexible diaphragm, anchored to the internal surface of said housing and connected to said frustonical shutter by a rigid stem.
Advantageously, a bypass pipe, connected to an upstream connector end part of said housing, allows a first face of said diaphragm to be subjected to said upstream pressure, the second face of said diaphragm being subjected to said downstream pressure prevailing in said chamber part that lies between said frustonical shutter and said diaphragm.
Furthermore, said means capable of defining said position of equilibrium comprise at least one screw/preloaded-spring assembly intended to act on said diaphragm/frustoconical-shutter/stem assembly.
According to another feature of the invention, said regulating means comprise, in a second chamber of said housing, this chamber being connected to said first chamber and subdivided into two chamber parts connected by a second orifice, a flat shutter facing said second orifice, which is rigidly connected, via a connecting stem and said stem, to said conical shutter.
The present invention also relates to a fuel circuit for an aircraft which, in a wing of this aircraft, has a fuel tank and a pipe leading to an engine, noteworthy in that it comprises a device as previously defined, mounted on said pipe.
Furthermore, in the fuel circuit for an aircraft, in which booster or backing pumps supply said pipe with fuel, this pipe having a low-pressure isolating valve, said device may be mounted upstream of said isolating valve relative to the direction of flow of the fuel toward the engine, or at the stub of said engine and therefore immediately downstream of the isolating valve.
REFERENCES:
patent: 2740604 (1956-04-01), Swigart et al.
patent: 3344805 (1967-10-01), Wapner
patent: 3428080 (1969-02-01), Brown
patent: 4210171 (1980-07-01), Rikuta
patent: 4250915 (1981-02-01), Rikuta
patent: 4278010 (1981-07-01), Wallischeck et al.
patent: 319675 (1978-08-01), None
patent: 4316484 (1994-11-01), None
patent: 0751448 (1997-01-01), None
Aerospatiale - Societe Nationale Industrielle
Hepperle Stephen M.
Stevens Davis Miller & Mosher L.L.P.
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