1. Title of the invention

Aircraft Dihedral Wing Tank Fuel Level Balancing Valve

2. Field of invention

It is a mechanical engineering design used for aircraft fuel system.

3. Use of invention

This invented valve finds its applicability in the civil aircrafts and military aircrafts which are having gravity feed fuel transfer from wing to fuselage tank.

4. Prior art

Stopping fuel flow from one wing to other Current practices are to use a non-return valve of spring operated type or flap operated type in the fuel transfer line from wing tank to the fuselage tank to avoid fuel going from one side tank to other side tank during roll maneouver or roll-Pitch maneouver. Fuel from the wing tank which is relatively in upper position only will feed supply tanks till such maneouver ends.

Imbalance corrections

Presently, for the correction of imbalance of wing tank fuel content, in each transfer line, solenoid valve or motorized valve are installed whose controls are done by a software or microprocessor taking feedback signals from both wing tank contents.

5. Draw backs of prior art

The fuel in the upper wing tank level is depleting as it is the one feeding supply tank whereas other tank fuel remains same as it is not feeding to fuselage tank. A fuel content differences in the wing tanks starts growing higher and higher when aircraft goes for roll maneouvers repeatedly.

1) When aircraft comes back from the maneouver, there are no simple means for correcting these fuel imbalances which causes center of gravity issues to the aircraft in turn affecting flight control

2) The flap type non return valves do not work properly when aircraft undergoes maneouvers. These valves use flap-hinge-gravity concept and perfectly work when the valve is kept in fixed favourable attitude.

3) The spring type non return valves do not allow transfer of fuel when the wing tank fuels are at low level as the pressure head available in the tank is not sufficient enough to overcome the valve cracking force to open the valve.

6. Comparison between prior art and present invention

This invented valve does all the functions of the non-return valves used in fuel transfer line and in addition it also corrects the imbalance of wing tank fuels when the aircraft comes to level flying or near to level flying for which the valve open / close conditions are designed for. It also eliminates the draw backs mentioned in the previous paragraph.

7. Aim of the invention

Aim of the invention is to eliminate the draw backs in the present practices / components and also to do imbalance correction using a single simple valve.

8. Summary of the present invention

This invented valve works as non-return valve for stopping flow of fuel from one wing tank to other during maneouver as the ball moves from center (default) position to one side port or other side port to close the passage by using simple "ball-gravity-roll on tilt" principle. During level flying or near to level flying, the ball rests at center to ensure that passage between both tanks is established to have auto level correction due to the head difference in the tanks (like in U tube manometer).

9. Brief description of drawings

Fig-l shows the cut sectional view of the Aircraft Dihedral Wing Tank Fuel Level Balancing Valve. In aircraft, it shall be mounted in the same orientation in the fuselage near supply tank i.e. normal to the gravity.

Fig-2 shows the valve position, when the aircraft goes for a roll which is more than the slope of the designed value. P

10. Statement of invention

This invented valve does all the functions of the non-return valves (and eliminates the drawbacks associated with NRVs) used in fuel transfer lines of wing tanks and in addition it also corrects the imbalance of wing tank fuels when the aircraft comes to level flying or an inclination near to level flying for which the valve open / close conditions are designed for.

11. Detailed description of invention

Refer fig-l. End fittings of the valve (4) are connected to LH and RH wing tanks each. Valve body is made of curved tube (5) (as shown in Fig-l) or two straight slanting pipes (not shown in Fig-l) meeting at center. The angle is to be planned in such way that the ball will roll over to side ports if aircraft roll is more than this designed value. The ball (3) in the center shows the default position of the valve which allows both wing tanks to communicate with each other. At this position, fuel from both wing tanks goes to the supply tank through the exit (1). In aircraft, valve shall be mounted in the same orientation in the fuselage near supply tank i.e. normal to the gravity. As shown in Fig-2, when aircraft goes for roll or roll-pitch attitude which is greater than the slope given in the curved tube (5), then ball (3) moves to the left side port or right side port and closes the passage. In this position, the fuel from the upper wing only will be transferred to supply tank through exit (1).

The ball (3) helps the upper wing tank fuel not to move into lower wing tank thus avoiding imbalance in a big way. Engine is consuming fuel from only upper wing tank through this valve till aircraft comes back from such maneuver. Whatever imbalance created due to such consumption of fuel from one side wing tank will be normalised by virtue of difference in wing tank heads (like an U tube manometer) when the aircraft comes to level flying or small roll angle of designed value. The end fitting sizes and transfer pipelines are sized in such way that within expected time, the levels balancing is done. The ball (3) is allowed to roll to the LH or RH side only but not fore and aft (during pitch up or pitch down of the aircraft) as they are guided by guides (2). During inverted flying, the ball (3) may be at any side of the ports and valve will not be transferring any fuel in this state because dihedral wings, no fuel is coming to this valve.

Claims

1. A single and simple valve replaces the need of two non-return valves in the fuel transfer line and need of two electrically operated valves, tank content sensors and an electronic controller.

2. This invention addresses the draw backs in the present practices / components and in addition does the fuel imbalance correction.