US2459807A

US2459807A - Multiple tank fuel system with emergency pump to maintain required discharge pressure

Info

Publication number: US2459807A
Application number: US526794A
Authority: US
Inventors: Edward M Gavin; Ralph E Grey; Leslie L Aspelin; George F Tate
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-03-16
Filing date: 1944-03-16
Publication date: 1949-01-25
Anticipated expiration: 1966-01-25

Description

Jan. 25, 1949. E. M. GAVIN ETAL 2,459,807

MULTIPLE TANK FUEL SYSTEM WITH EMERGENCY PUMP TO MAINTAIN REQUIRED DISCHARGE PRESSURE Filed March 16, 1944 IN VENTORS Eon/4gp M GAVIN Patented Jan. 25, 1949 r MULTIPLE TANK FUEL SYSTEM WITH EMERGENCY PUMP TO MAINTAIN RE- QUIRED DISCHARGE PRESSURE Edward M. Gavin, Las Vegas, Nev., and Ralph E. Grey, Osborn, Leslie L. Aspelin, Elyria, and George F. Tate, Dayton, Ohio Application March 16, 1944, Serial No. 526,794

5 Claims. (01. 1583 6.4)

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to fuel systems, and is particularly applicable to systems employing a plurality of fuel tanks, such, for instance, asthe fuel system on an aircraft.

An object of the invention is to provide a fuel system of this character with means to maintain the pressure in the fuel line at its entrance to the carburetor or other fuel metering device substantially constant, while changing the connection which extends from the suction side of the main fuel pump from one tank to the next, as successive tanks are emptied.

More specifically, an object of the invention is to provide an emergency pump which becomes operative upon failure of the main pump to maintain the desired discharge pressure, and remains operative until the main pump has resumed substantially full discharge capacity.

Another object is to provide means to indicate when a shift from one main tank to the next should be made.

Other objects and advantages will become evident from a consideration of the following description, taken in conjunction with the drawings, wherein,

The single figure of the drawing is a schematic assembly view of the various elements of a fuel system arranged and connected according to the principles of our invention.

Like reference characters refer to like parts throughout the drawing.

Referring now to the drawing, an engine l carries a main fuel pump l2 which is operatively connected to the engine to be rotated thereby, and adapted to maintain a given constant fuel pressure at the fuel inlet l3 of the carburetor M. A gauge l 5 and a signal light I! are provided for indicating when the fuel is being maintained at the desired pressure. A suction line It extends through a strainer If! to the common outlet of the tank selector cock 2!], the several inlets to the tank selector cock being respectively connected by

supply pipes

22, 24 and 26 to the tanks 28, 30 and 32. The supply pipes 22 and 24 stop at the bottoms of their respective tanks 28 and 30, but the supply pipe 26 is prolonged so as to extend upwardly into the tank 32 as at 34, so that a reserve quantity of fuel 36 remains in the tank after the pipe 26 has drawn off fuel to the level of the upper end of the part 34. A short discharge line A-pressure responsive switch 44 completes electrical connection between the battery 42and. the motor 40 and signal light [1 whenever the-pressure at the carburetor fuel inlet l3 fallsseveral pounds below the predetermined pressure whichthe pumps l2 and 38 are set to maintain. Conduit means 46 connects the carburetor fuel inlet I3 to the pressure operated part of the switch 44. A discharge line 48 connects the dischargeside of the emergency pump 38 into the short conduit 3! at the discharge side of the engine pump. A suction line 50 extends through a manually'operable reserve connector cock 52 into the bottom of the tank 32, whereby the suction. side vofthe emergency pump 38 is connected to the-reserve fuel supply 36. v

An air eliminator line 54 extends fromthe carburetor to the bottom of an air eliminator tank 56, which is partially filled with a liquid. A valve 58 inthe line 54 permits it to be shutoff when that becomes desirable; Since both pumps l2 the damaged one, and for that reason, checkvalves 62 and 60 are provided, both biased to prevent backward flow in the lines It andii48,

respectively. The pressure responsive part-ofl the automatic switch 44 may preferably be somade that the switch, in shutting off the motor 40, will respond to a pressure several poundslower than that at which the relief valve ofthe pump I2 is set. I

Assume that the engine. In is -stopped,,the pressure at the carburetor inlet l3 has dropped, and the tank selector cook 20 is turned to the position which connects the tank 28, through the supply pipe 22 and suction line IE to the suction side of the engine pump l2. If the manual switch 43 is now closed, the emergency pump 38 will prime the carburetor, the switch 44 shutting off the motor when the pressure is up. If the engine is not immediately started, the emergency pump A manual switch 43 isprovided for dis-- connecting the battery from the electric circuits.

The operation of the fuelsystem shown and described is substantially as follows: 1 i

the discharge line 48 from flowing backwardly' through the pump 38 into the tank.32.

When the tank 28 becomes empty, it will be a matter of several seconds only until the engine pump [2 will be drawing some air through the suction line l6 and discharging it into' the short conduit 31. When this occurs, the pressure-at the fuel inlet l3 will drop almost instantly, and the automatic switch 44 will beactuated thereby to connect the battery 42,100 the motor 40 of the emergency pump 38, whereupon the emergency rmrnp38 will maintain the desired fuel pressure at the carburetor fuel inlet l3,fthe air which had gotten into the short'conduit 31 and into the carburetor, "being discharged through the air eliminator line-54. It is noted that the discharge line 48 of the motor driven pump 38 isalways full of fuelso that it needs only to be put under pressure to enable the pump 38 to take over when the pump l2fails. v

The pump 38 is', ofcourse, designed for greater capacity than engine consumption, and may thereforecycle from this cause at intervals of several seconds. Thus the pressure at the fuel intakel3-wil1 reach the desired value and the automatic switch u wnr stop the motor 48, then, as-fuelaisconsumed, the'pressure will drop at the inlet I ii a matter of 7 several pounds, whereupon the switch will again start the motor 48 to opcrate the pump 38. i

This cycling may-be observed on the pressure gauge l5,andby the fiashingof' the signal light l"I",-whereupon thetank-selector cook 20 should be turned to connect the tank 30 or any other full tank tothe suction side of the engine pump l2. Qrd-inariIy, in less-than half a; minute, the pump 12' picks up the prlmeand raises-the pressure at the fuel inlet 1 3 high enough to shut off the switch 44: andthusstop the motorpump '38.

If thesystem shown isbein used in combat aircraftg'it may happen that; the tank 32 is punctuned and the reserve: supply 36 lost, or the engine pump l2' maybe jammed ior otherwise incapacitated; I-In.such'a:case, the'reserve connector cock 52 i:maybe "turned sons to connect the motor driven pump 38, through the tank selector cook 28, to any tank whichmaystill contain fuel.

Having shown and described a physical embodiment-of our invention, we claim:

LfThe combination .inaan aircraftfuel system, of-a main'fuel-supply receptacle," a main fuel pump-having its xsuction side connected to said main fuel supply-receptacle, a discharge-pressure control means for said main fuel pump, a reserve fuel supply container, an auxiliary fuel pump having its suction. side connected to said reserve fuel supply container, a; discharge-pressure controlmeansf'or saidauxiliaryfuel pump, a fuel receiving means,the discharge side of both said pumps being connected to said fuel receiving means, the discharge-pressure control means of the auxiliary'fuel-pump being operable at the same pressure as the main fuel pump for delivering fuel to said fuel receiving means, and a pros sureresponsive means'associated with the main fuel pump, adapted upon a predetermined drop 4 in pressure at the discharge side of the main fuel pump to operate said auxiliary fuel pump.

2. The combination, in an aircraft fuel system, of a plurality of main "fuel supply receptacles, a main fuel pump, a discharge-pressure control means for said main fuel pump, valve means for connecting the suction side of said main fuel pump to any of said receptacles one at a time, a reserve fuel supply container, an electric motor driven auxiliary fuel pump, a discharge-pressure controlmeans for said auxiliary fuel pump, means for connecting the suction side of said auxiliary fuel pump to said container, a fuel receiving means, means connecting the discharge side of both said pumps to said fuel receiving means, the discharge-pressure control means of the auxiliary fuel pump being operable at the same pressure as the main fuel pump for delivering fuel to said fuel receiving means, and an automatic electric switch responsive to a predetermined drop in pressure at the fuel inlet opening of said fuel receiving means to 'close and'direct an electric current to operate said'electric motor driven auxiliary fuel pump.

3. The combination, in an aircraft fuel system, of aplurality of main fuel supply receptacles, a main fuel pump, means for selectively connecting the suction side of said pump to any of said supply receptacles one at a time, a reserve fuel supply container, an auxiliary fuel pump, means connecting the suction side of said auxiliary fuel pump to said reserve fuel supply container, a fuel metering means, the discharge side of both said pumps being connected to said fuel metering means, valve means for disconnecting the suction side ofthe auxiliary fuel pump from said reserve fuel supply container and connecting it into the suction ;-line of the mainfuel pump, and a pressure-responsive means associated with the fuel metering means, adapted, upon a predetermined drop inpressure at the fuel intake of said fuel metering means. to operate said auxiliary fuel 4, The combination, in an aircraft fuel system, of aplurality of main fuelsupply receptacles, a main fuel pump, a selector Valve for connecting the suction inlet of said main fuel pump to said main fuel supply receptacles one at a time, a reserve fuel supply container, ,an auxiliary fuel pump, a reserve connector cock, a first, a second and a third port in said connector cook, a first passageway connecting the first port to the reserve fuel supply container, a second passageway connecting the second port to the suction side of the auxiliary pump, a third passageway connecting the third port into thesuction line of the main fuel pump, means in said reserve connector cock operable to one. position to connect the first port to the second, and to a second position toconnect,

thesecon-d port to the third, a check valvein the suction line of said main fuel pump between said main fuelpump and the point of. connection of the third said passageway with the main pump suctionline, a carburetor, the discharge sides of bothsaid pumps being connected to the fuel inlet of said carburetor, and an automatic means re sponsive to pressure drop at the fuel inlet of the carburetor to operate said auxiliary fuel pump.

5. The combination, in an aircraft fuel system, of a plurality of main fuel supply tanks, a main fuel pump, conduit means including a tank selector cock for selectively connecting the suction inlet of the main fuel pump to the several tanks one at a time, a checkvalve in said conduit meansbetweensaid selector .cock' and 1 said main vfuel pumnbiasedto-prevent fuelr flow from said pump back through said cook, a reserve fuel supply container, an emergency fuel pump, conduitmeans including a two way cock for selectively connecting the suction inlet of the emergency fuel pump either to the reserve fuel supply container or to 5 the said main fuel pump conduit means at a point between said check valve and said tank selector cock, a carburetor, a conduit connecting the discharge sides of both pumps to the fuel inlet of said carburetor, a check valve in said conduit biased 10 to prevent fiow from the discharge side of the main fuel pump back through said emergency fuel pump, and an automatic means responsive to a pressure drop at the fuel inlet of the carburetor to operate said auxiliary fuel pump.

EDWARD M. GAVIN. RALPH E. GREY. LESLIE L. ASPELIN. GEORGE F. TATE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS