Description:[0001] TITLE
Accumulator for fuel supply system

[0002] FIELD OF THE INVENTION
Present invention related to fuel accumulator for fuel supply system of aircraft to provide cavitation free fuel supply to engine irrespective of ‘g’ loads with zero overload.

[0003] BACKGROUND OF THE INVENTION
The purpose of an aircraft fuel system is to store and deliver the correct amount of clean fuel with positive, reliable pressure and flow rate to engine throughout all phases of flight by means of booster pumps. However, under the effect of negative and zero g-load, the fuel flows back from booster pumps and pump fail to develop required pressure for positive supply of fuel to engine, this interrupted fuel supply may cause the formation of cavitation, less or no fuel supply and results to engine flameout. To avoid this interrupt fuel, supply a zero-overload low pressure fuel accumulator is design to provide uninterrupted fuel supply to engines operation at all modes, when there is no g-load of negative g-load in three planes at the same time.

[0004] BRIEF SUMMARY OF INVENTION
The fuel accumulator comprises, A housing, made of two metallic shell halves (1,2), flexible rubber-fabric membrane assembly (3)-connected among themselves with bolts (4) and Nuts (5), from inside the accumulator housing is divided into air chamber(6) to accommodate air and fuel chamber (7) to accommodate fuel by means of membrane (3), a fuel connection (8) for fuel flowing into and out of the fuel chamber(7) and air connection (10) for air flowing into and out of air chamber (8), a drain connection (12) on air chamber shell (2) for draining fuel, a breather connection (10) in fuel chamber flange (11) to avoid over pressurization of fuel chamber. Fuel Accumulator (30) is positioned inside the aircraft fuel tank (31) and installed in engine fuel supply line (32) after the booster pumps (33). Accumulator stores specific volume of fuel to cater fuel supply during negative and zero g-load cyclic duration (approx. 9s to 10s). At normal flight, the fuel chamber of the fuel accumulator is filled with fuel and diaphragm (3) is bent towards the air chamber (8), thus max fuel volume and minimum air volume at that time. When zero G-loads appears, pressure drop downstream the booster pumps (33), the pressure in fuel chamber (8) of the accumulator becomes less than pressurizing pressure supplied to the air chamber (7). Due to differential pressure in air and fuel chambers, the diaphragm (3) is bent and displaces the fuel from the accumulator to the engines (34). After termination of zero g-loads action, fuel pumps (33) create again the pressure exceeding the pressure of the air chamber of the accumulator, and the fuel chamber is filled with fuel. Pressure in the air chamber is maintained with the help of drain valve (35), to avoid fuel flow from accumulator to pumps or one pump to other, check valves (36) are installed in the supply line between pumps and accumulator. The specific requirement of fuel accumulator of aircraft is differed from the other state of art pressure accumulator.

[0005] BRIEF DESCRIPTION OF DRAWINGS
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the following drawing.
Figure-1: Schematic diagram indicates of accumulator & its parts
Figure-2: Inventive fuel accumulator as an enlarged representation.
Figure-3: Schematic diagram for position of fuel accumulator in a typical fuel system of aircraft.

[0006] DETAILED DESCRIPTION OF THE INVENTION
The invention related to fuel accumulator (30) for fuel system of aircraft to provide cavitation free fuel supply to engine (34) irrespective of ‘g’ loads in flight with zero overload. During negative and zero g-load maneuvering of aircraft, the fuel flows back from booster pumps (33) and pump fail to develop required booster pressure for positive fuel supply. This leads to engine flameout and cavitation in the fuel supply line due to interrupted fuel supply in typical aircraft fuel system. Therefore, fuel accumulator is being introduced in supply line of fuel system. The function of invention is to store the required amount of fuel during aircraft experience positive g load and supply fuel during aircraft experience negative g load or zero g load at required pressure. The specific requirement of fuel accumulator of fighter aircraft is differed from conventional and state of art pressure accumulator. The aircraft fuel accumulator is design to provide uninterrupted fuel supply to engines operation at all modes, when there is no g-load of negative g-load in three planes at the same time. It should be installable inside the fuel tank, have minimum moving parts, less in weight, should auto discharge of pressure in air and fuel chamber during engine off condition.
The invented Fuel accumulator is a zero-overload accumulator schematically depicted in Figure-1 is a cylindrical form cistern with bumped heads, which is assembled of two shells (1, 2). Shells form two cavities – fuel cavity (7) and air cavity (8), which are separated from each other by double rubberized caproic membrane (3). Figure -2 shows an enlarged schematic representation. Manifolds/Cases are welded to external surface of shells. Cases serve for structural rigidity of shells and manifold for fuel supply, which is forced out of fuel chamber (7) by membrane, to the fuel tube. Shells having number of holes (20) for in and out flow of fuel from fuel chamber (7), number of holes (21) for in and out flow of air from air chamber (8), the total area of no of holes should be greater than the area of fuel connection (9) and area of air connection (10) respectively. In top part of one shell: there is fuel connector (15) through which fuel is forced in/out of fuel cavity of accumulator at cavity filling with fuel. In another shell: there is pressurizing air connector (22) of accumulator air cavity. Fuel accumulator shall be placed in aircraft tank and installed on bracket-cradles and is attached to frames of tank and fuel connection is connected to the fuel supply line and air connection is connected to the pressurized airline. Accumulators is design for specific volume of housing to store the useable quantity of fuel, shall discharge the useable quantity of fuel for within specific time duration with specific supply rate range, shall recharged within specific time, shall withstand considerable pressure, shall be airtight and reliable while being mechanically simple and having a minimum number of parts. Both air and fuel shall be charged and discharge with start of engine, all the joint of accumulator shall be air tight, the air connection shall be opposite to fuel connection, fuel connection shall be such that fuel should be discharge by gravity in case of no air pressure. This invention makes it possible to make an accumulator having valuable features mentioned and render the same, an important feature in the construction is described makes it possible for the movable element of the accumulator to move from one end to other end i.e its discharge stroke to charge stroke without danger of mechanical shock. Suitable air pressure is applied to one side of membrane. On the other side of the membrane and within the casing structure as a whole is a quantity of fuel. As pressure in fuel side drop below the air pressure, the membrane moves under air pressure, the fuel is pressed and supplied to supply line. By suitable design of the thickness and dimensions of the shell casing, the capacity of the accumulator may be varied. Thus, accumulators of this type may have a length and width of from several inches up to as much as four feet or more. A feature of the present invention resides in the construction. This feature is of substantial importance in accumulators having substantial size of shells, shells having number of holes (20,21), drain connection (11), a breather hole (12) to avoid over pressurization of fuel chamber, holding the accumulator with the mounting brackets, connected with Nuts (4), bolts (5) and washers with fuel accumulator housing. The means are provided at the metallic shell halve (1) in form of number of holes (20) for in and out flow of fuel from fuel chamber (8), at the metallic shell halve (2) in form of number of holes (21) for in and out flow of air from air chamber, the total area of no of holes are greater than the area of fuel connection (9) and area of air connection (10) respectively. The means are provided at the metallic shell halves in form of welded fuel manifold (18) above holes portion to make smooth passage for in and out flow of fuel from fuel chamber (8), fuel manifolds (18) are connected themselves and with fuel connection flange (15) for in and out flow of fuel from fuel supply line and air manifold (17) connected themselves and air connection (22) of flange (14) for in and out flow of air from air chamber (7). The means are provided for breathing in form a breather hole (10) in fuel chamber flange (11) to avoid over pressurization of fuel chamber. The means are provided in form of bracket (16) for inter-connection of air connection (22) with aircraft for in and out flow of air, bracket (15) connected with accumulator housing with Nuts (4), bolts (5) and washers (6). The means are provided for a draining the fuel in form of drain connection (12) on air chamber shell (2) in case failure of membrane assembly (3). The means are provided at the mounting flange (13,14) in form groves (23) for installation of seals (24) and at air connection (22) of flange (14) in form groves (25) for installation of seal (26) to ensure leak proof and airtight accumulator housing. The means are provided in form of mounting brackets for holding the accumulator, connected with accumulator housing with Nuts (4), bolts (5) and washers (6).

, Claims:1. An accumulator (30) for fuel supply system comprising:
A housing, made of two half shell (1,2), plurality of a flange (13,14), a flexible membrane assembly (3), a bracket (16), plurality of seal (24,26) connected among themselves with Nuts (5), bolts (4) and washers (6);
A fuel connection (9) for fuel flowing into and out, an air connection (10) for air flowing into and out, from inside the accumulator housing is divided into air chamber (7) and fuel chamber (8) by means of the membrane (3); and
Wherein said Half shell (1,2) with plurality of holes (20, 21), plurality of manifold (18,19) above said holes portion, a drain connection (11) on the air side half shell (2), a flange (15) welded with said fuel manifold (18), said Flange (13,14) consist a grove (23), a breather hole (12) on said flange (13), a grove (25) on the air connection (10) on said flange (14).

2. The accumulator as claimed in claim 1, is a zero overload accumulator, with capacity of one liter to sixty liter or more, made of metallic and nonmetallic material has number of holes (20,21) on half shell (1,2) varies from four to hundred or more to have the total area of no of holes is greater than the area of fuel connection (9) and area of air connection (10) respectively, has a breather hole (13) of diameter less than two mm in fuel chamber flange (12) to avoid over pressurization of fuel chamber, has a metallic bracket (16) for mounting with air pressurization line and applied for in and out flow of pressurized air.