US2333075A - Fuel feeding system - Google Patents

Description

Get. 26, 1943. 3 E 2,333,075

FUEL FEEDING SYSTEM Filed Sept. 21, 1940 3 Sheets-Sheet l VOL/47'ILE FUEL TAN/(5.

JUPERCHARGER.

JE'LECTU? VALVE Oct. 26, 1943. H. D. ROE 2,333,075

FUEL FEEDING SYSTEM 1 Filed Sept. 21, 1940 3 Sheets-Sheet 2 Oct. 26, 1943. H, D. ROE 2,333,075

FUEL FEEDING SYSTEM Filed Sept. 21, 1940 3 Sheets-Sheet 5 flrner )9. foe

Patented Oct. 26; 1943 FUEL FEEDING SYSTEM Homer D. Roe, North Hollywood, Calif., aslignor to Pump Engineering Service Corporation, Cleveland, Ohio, a corporation of Ohio Application September 21, 1940, Serial No. 357,825

Claims.

This invention relates td fuel supply systems,

and particularly to aircraft fuel feeding systems for high altitude flying.

It has been found that certain limitations in previously available fuel systems constitute the,

be lifted from the tank to the engine. Also of importance are the effects introduced by the necessary location of the volatile fuel storage tanks a considerable distance from the engines as well as the effects introduced as a result of maneuvering the aircraft, It has been recognized heretofore that any solution to the present problem must include means to force or push the volatile fuel from the level of the supply tank to the higher elevation at or adjacent the engine as differentiated from producing this movement of the fuel by a suction pump. All such systems, however, leave considerable to be desired in the particular arrangement of means for accomplishing this result as well as in the control mechanism forfsuch means. 1 i

It is an object of the present invention to provide an improved arrangement of means for transferring volatile fuel from a tank located at a first position on an aircraft to a fuel consuming engine located at a second position remote from said first position while maintaining a substantially constant pressure in said transfer stream which pressure is safely'above a predetermined minimum pressure below which vapor bubbles would be introduced into said stream notwithstanding the effects produced under flying conditions. Y

A more specific object is to provide a fuel feeding system for aircraft which is effective to store volatile fuel and transfer the same from a first elevation at. which the storage meansis located to a second higher elevation at which is located the means for introducing fuel into'the aircraft engine while maintaining the pressure in the transfer line at all points above a predetermined minimum critical pressure below which the hi ly volatile fuel would be pulled apart and dissolved air bubbles and vapor bubbles mixed there- A more detailed obiectflis the provision of a. volatile fuel pumping system effectiveto produce the above result wherein the fuel pump is located at or adjacent the fuel tank and driven indirectly from the aircraft engine, the system being so operated and controlled that the output of the fuel pump is substantially exactly that demanded by the air craft motor with the result that there is no appreciable whipping up or frothing of the fuel such as is commonly present in known systems, as for example, in the relief valve type of pump, wherein there is normally an excess amount of fuel pumped by the pump, which excess fuel is bypassed back from the outlet to the inlet of the pump resulting in objectionable disturbance of the fuel and in the introduction of air bubbles therein.

Another specific object is the novel application to the present problem of the variable eccentricity type of adjustable displacement pump disclosed in Johnson Patent No. 2,192,660.

The above and other objects, advantages and uses of my invention will become more apparent from a reading of the following specification and claims taken in connection with the appended drawings which form a part of this specification, and wherein:

Fig. 1 is a broken away perspective view of an airplane on which is shown mounted a preferred modification of a pumping system incorporating of volatile fuel in accordance with my invention,

this view being indicated generally 4-4 of Fig. 2;

Fig. 5 is an axial sectional view indicated generally by the line 5-5 on Fig. 2, and showing the inner construction of a rotary constant displacement fluid motor particularly adapted to the present system for driving the constant displacement fuel pump of Fig. 4;

. Fig. 6 is a transverse cross-sectional view taken substantially on the line 8-8 of Fig. 5 and bringing out to advantage the path of flow of driving fluid; and

Fig. 7 is a developed view of that portion of the on the line intermediate housing immediately surrounding the pump rotor and brings out to further advantage the path of flow of driving fluid.

Referring to Fig. 1, there is illustrated schematically in perspective an aircraft indicated generally at l embodying a preferred modification of the fuel feeding system forming the subject matter of the present invention. Airplane l0 includes the usual outwardly extending wing structures II and the forwardly protruding propeller driving motors |2 of one conventional form to which my invention is applicable. The motors 12 are provided with the usual form of fuel introducing means or carburetor indicated generally at l3, fuel being supplied thereto from selected ones of a plurality of volatile fuel supply tanks l4 carried in the wing structure II, this fuel delivery being accomplished by means of my novel pump ing arrangement indicated generally at ii, the arrangement for one motor only being illustrated in order to simplify the disclosure.

Referring particularly to Fig. 2, it will be seen that my volatile fuel transfer or pumping system indicated generally at l5, comprises essentially a constant displacement rotary'fuel pump I6 located relatively close to or below the fuel in the tanks l4 and arranged to push or force the volatile fuel up through lin H to the carburetor |3 as differentiated from pulling or sucking up the same to increase the elevation thereof.

A feature of particular importance is the provision of a novel fluid power transmitting system for driving fuel pump |6 directly from the aircraft motor I2. This novel arrangement comprises a rotary variabl displacement hydraulic generator or pump 2| (see also Fig. 3) driven directly from the aircraft motor l2 and delivering liquid such as oil or glycerine under pressure through a closed circuit 22 to a rotary constant displacement hydraulic. motor 23 mechanically connected to the pump It for driving the same.

Turning now to the inner construction of hydraulic generator 2| shown to advantage in Fig. 3;, it will be seen that this generator is of the general type of the pump disclosed in Johnson Patent .No; 2,192,660 with certain important changes incorporated I for the purpose of particularly adapting the same to the solution of the present problem. .More specifically, pump 2 includes essentially'a housing 30 formed with a transverse generally circular bore 3|, ports 32 and 33, either of which may be the inlet or outlet depending on the direction of rotation and a variable displacement rotary'pumping assemblyinterpos'ed between said ports and indicated generally at 34 for receiving the*low volatility hydraulic medium from said inlet port and delivering the same to said outlet port at an increased pressure, and y, with control means indicated generally at 36 for adjusting the displacement of the pumping assembly under definite conditions to be pointed out. Pumping assembly 34 includes-a first sleeve or intermediate housing 36 formed with ports 31 and 36 cooperating respectively with ports 32 and 33.; Within said secondary housing 36 is a. sleeve 39 having an outside dimension considerably smaller than the inner bore of intermediate housing 36 and provided with protuberances 46 and 40a, received in complementary guide recesses formed in intermediate housing 36 providing for sliding adjustment of sleeve 39 to vary the eccentric relation thereof with respectto rotor 41, which rotor has a fixed axis of'rotation. Sleeve 39 is further provided with ports 42 and 43 cooperating with the corresponding ports 31 and 38 on housing member 36. Fixed axis rotor 4| supports a plurality of reciprocable blades 44, the outer edges of which engage the inner periphery of sleeve 39 while the inner position of these blades is controlled by a floating cylindrical member 45.

From the above it will appear that the displacement of pump assembly 34 is directly proportional to the eccentric displacement between the fixed axis of rotor 4! and the shiftable axis of sleeve 39. In the position shown in Fig. 3 with sleeve 39 in the most eccentric position thereof with reference to the rotor 4 I, the pump will have maximum displacement, while by lowering sleeve 39 to a position where the axis thereof substantially coincides with the axis of the rotor 4|, the pump will have its minimum displacement, which is zero. b

In order to properly control the eccentric relationship of sleeve 38 with reference to rotor 4|, and hence control the displacement of pump 2|, there is provided diaphragmassembly 35 which comprises a generally disc-like flexible diaphragm 50, the' outer peripheral edge of which is confined betweenthe housing 30 and a cover member 5| therefor, the central portion being confined between two metal disc-like members 52 and 53 for lending support thereto, this assembly being in turn connected at the central portion thereof to sleeve 38 by stem 54. The two limits of adjustment of this assembly are defined by a lower limit of movement threaded lock member 55, and an-upper limit of movement threaded lock member 56.

It will be seen from the above that the upper side of the diaphragm assembly and the adjacent portion of cover member 5| define a first chamber designated 60 while the lower side of the diaphragm assembly and the adjacent portion of the housing define a second chamber 6|. Referring to Fig.- 3, it is important to note that the first chamber 60 is placed in communication through fluid pressure control line 62 with the fuel being delivered to carburetor l3, by pump l6, so as to make control assembly 35 respond to changes in the fuel delivery pressure at the carbureter.

It is important to note that there is a small clearance provided between sleeve 39, guide protuberance 4|l,stem 54 and housing 30 providing for a definitely limited metering of fluid from the generator outlet into chamber 6| under conditions to be pointed out.

Of particular importance is the provision of means indicated generally at Ill and 1| for placing chamber 6| in communication respectively with the discharge side and inlet side of the pump under certain conditions of operation in connection with effecting the adjustment of the pump displacement in response to changes inthe pressure. of the fuel delivery to carbureter l3. The means I0 and 1| are substantially identical and include passages I2 in housing 36 com- 'municating with a valve chamber 13 formed with a valve seat 14 receiving a ball check valve 15 urged toward its closed position by a spring 16. Valve seat I4 communicates with chamber 6| through passage I1 in housing 30. A closure member I8 closes the end of valve chamber 13 and includes an inwardly protruding stop member 19 limiting the opening movement of ball check valve 15, this closure member being held in position by a threaded locking plug 80. It will be noted that pin 19 is square in cross-section cooperating with an externally threaded spring seat member 19a for adjusting the same to vary 2,sss,o7s

employed at I8, in Fig. 2, I find that a pump conthe compression of spring I6, this adjustment being eiiected as by a screw driver receiving socket'lla. v

a Two check valve assemblies and 'II are provided in order that the gen'eratormay be'made to function in either direction depending on the particular installation, without the usual need for rearranging certain elements of the gen-w orator. y

In operation, assuming for example rotation in a clockwise direction looking at- Fig. 3, ball check valve I! in communication with port 33, now the discharge port, will be held tightly in engagement with its seat I4 by both the discharge pressure and spring I6. Hence there will be no flow through this forward one of the valves I5 for clockwise operation of the generator.

It is important to note that oil under discharge pressure is gradually metered to lower chamber OI through the small clearance space between sleeve 39, intermediate housing 38, stem 5i and main housing 20. as indicated by arrows 54a. The pressure in chamber "I is thus gradually built up to some value below the value of the discharge pressure determined by the action of the ball check valve II in communication with the pump inlet or suction side. The opening of the valve to allow oil to pass out of. chamber H to the pump inlet is primarily determined by the degree of compression of spring 16, which may be readily adjusted. For example, in practice the spring I6 may be set to allow-valve I5 to open when the pressure in chamber 0| reaches about 15 p'. s. i., this being about 35 p. s. i. below the normal pressure of 50 p. s. i. at which the hydraulic system is normally operated. This will allow the excess 'oil in chamber II to leak out through valve 15 and into the pump or generator inlet thus main taming a definite predetermined oil pressure in chamber SI of 15 p. s. i. and'hence with this constant oil pressure in chamber II below diaphragm II, the pressure of the volatile fuel in chamber acting on top of diaphragm becomes; ef-' fective to adjust the displacementfof the generator in response to variations in'the pressure of. the volatile fuel being delivered to' the carbureter ii. The fuel delivery pressure will be maintained equal to the oil pressure in chamber ll, which pressure may be varied by adiustins the compression of spring 18 as by means of a screw driver turning square pin I9. 7 I

Since as shown in Fig. 2, supercharger pressure is applied to the oil tank I24 as well as to the carburetor air stack, there will be an increase in fuel delivery pressure corresponding tothe increase in'air supply. The increased air pressure on the oil in tank I24 causes an increase of the inlet suction pressure at generator 2| and since valve I5 is not balanced against inlet suction, this increase in inlet pressure has the effect of requiring a greater oil pressure in chamber ii to cause opening of valve 15. This in turn results in a greater pressure of the volatile fuel being required in chamber 00 to balance diaphragm ill or to produce equilibrium. Thus fuel pressure will be responsive to supercharger pressure and the fuel pressure at the carbureter will be maintained at a constant differential above carbureter air stack pressure. a I

It will be understood that generator2i will operate equally effectively in a counterclockwise direction in an installation requiring this direction of flow.

While other commercially available forms of rotary constant displacement fuel pumps may be structed as illustrated in cross-section in Fig. 4 functions to particular advantage in the present relation. This pump is ofthe general construction shown in Johnson's Patent No. 2,170,530 and includes essentially'a housing indicated generally at "formed with a generally circular transverse bore 9| communicating with an inlet port 92 and fixed eccentric relationship with respect to fixed axis rotor 96, which in turn carries pumping vanes or blades 81. n 1 V As aprecautionary measure-only, pump I6 is provided with a relief valve assembly indicated generally at I00 for returning excess fuel from the pump discharge side back to the pump inlet under conceivable emergency conditions where the discharge pressure of pump I6 may be caused to rise above a predetermined value. This release valve assembly will not operate under normal fuel feeding conditions but only under such emergency conditions as noted above. This relief valve assembly includes a disc-like valve IDI balanced against the effects of pump inlet suction by a disc-like flexible diaphragm I02, this being accomplished by giving to the flexible diaphragm assembly I02 the same effective suction area as that ofvalve II. The upper side of diaphragm assembly I02 is placed in communication with the pressure existing within the fuel introducing that which the pump I6 is set to normally deliver.

- It is important tonote this. distinction over the conventional arrangement wherein the relief valve therein corresponding to valve IIII of pump I6 is set to normally by-pam a predetermined" fraction of the output of the pump and is not merely operated under emergency conditions as herein disclosed.

Turning now to Figs. 5, 6 and 7, there is illustrated the preferred construction of rotary constant displacementhydraulic motor 23 particularly adapted for driving the constant displacement fuel pump IS in response to the fuel pressure generated by variable displacement pump 2 I. It will be understood that while I prefer this type of fluid motor because of its satisfactory operation in this connection, I nevertheless contemplate the use of other forms of rotary constant displacement hydraulic motors as coming within the broad scope of my invention. Motor 23 comprises a housing indicated generally at I I0 I formed with a transverse cylindrical chamber charge port H2. The motor assembly I22 ineludes essentially a rotor I II arranged to be drivingly connected to constant displacement fuel pump it, and supporting thereabout a plurality of axially reciprocabie fiuid responsive driving: blades or vanes Ill. 'I'hereciprocation of these blades H4 is accomplished by means of a pair of juxtaposed cams H5 and H6. Interposed between the periphery of-rotor H3 and housing proper H0 is a secondary embracing housing or sleeve-like member. lil formed with inlet ports H8, including communicating channel H9 and discharge ports I20 for conducting fluid under pressure respectively into contact with driving blades H4 and discharging the same after doing the necessary work of turning the motor. a

In addition to the above, there is included in closed circuit 22 an accumulator or tank I24, and it will be noted that the same comprises an inlet fromthe discharge side of constant displacement fluid motor 23 and an outlet connection to the inlet side of variable displacement hydraulic generator 2|, and contains no complicated internal mechanism. In order'to effect the proper balance of pressure, control line I03 places tank I24 in communication with the carbureter l3 and the upper sideof' diaphragm assembly I02.

Also provided is the usual supercharger assembly indicated generally at i25,'and functioning in its conventional capacity to raise "the inlet air pressure to the carbureter l3.

The volatile fuel is selectively conducted to the inlet side of fuel pump 'it by means of valve I26 delivering through a strainer l2'l. 1 It will now be seen that theabove described pumping arrangement functions to deliver substantially exactly thequantity of fuel demanded by the 'aircraftmotor II at any particular time and does so while maintaining the volatile fuel in delivery line I! always above a predetermined minimum pressure below which vapor loo might occur. Under normal operating conditions and over a wide range offuel consumption rates,

pump it is driven at the correct speed to deliver a, substantially constant pressure at carbureter l3, irrespective of any centrifugal or other effects 345 to which line is subjected by virtue, of maneuvering the plane or by virtue of differences in elevation between the fuel supply tanks It and the carbureter l3.

While I disclosed my with a certain specific embodiment thereof, it is to be understood that the same has a broad application, obvious changes being apparent to those skilled in the art, and it is intended thatmy invention be defined by the appended claims. -I claim: 1. In a high altitude volatile fuel supply system for aircraftmotors, including carburetor means adjacent said aircraft motors for introducing fuiel therein, volatile fuel storage means located at an elevation below that ofsaid introducing means, and means for moving said volatile fuel from said storage means to said carbureter means'located thereabove while maintaining the pressure of said fuel at a value above the point below which vapor lock would normally occur by the fuel being pulled apart, said means comprising aflrst rotary fuel pump located at substantially the level of said storage means in communication with the volatile fuel and effective to force the same above the level of the fuel pump to said introducin means, a liquid ressure responsive rotary motor for driving said fuel pump, a second'rotary liquid pump driven, from said aircraft engine, means defining a closed liquid power transmitting cirinvention in connection cuit connecting said second pump and said liquid motor, said circuit including a relatively nonvolatile pressure transmitting liquid, said arrangement being particularly characterized by the fact that said second pump is of the variable displacement type including a rotor having a fixed axis, a sleeve embracing said rotor, said sleeve being adjustable with reference to said rotor for varying the eccentricity therebetween, said second pump having means for effecting said adjustment comprising means defining a chamber adjacent saideccentric rotor, a'diaphragm in said chamber dividing the same into two compartments, means connecting the central portion of said diaphragm to said sleeve, means placing one side of said diaphragm in communication with said liquid pump outlet and means placing the other side of said diaphragm in communication with the pressure at said volatile fuel introducingvmeans whereby to control the displacement of said second liquid pump in accordance with the delivery of pressure of said volatile fuel at said introducing means.

2. In an aircraft fuel supplysystem, means adjacent the aircraft engine for introducing fuel thereto, a tank adapted to receive a volatile fuel located at an elevation below that of said introducing means, a first pump located adjacent said tank and in communication with the fuel therein, a fuel line leading from said pump to said introducing means, a liquid responsive motor drivingly connected to said pump, a second pump driven by said aircraft engine, means defining a closed liquid circuit connecting said second pump and said liquid motor including a relatively nonvolatile liquid power transmitting medium, said second pump driven by said aircraft engine including means I for varying the displacement thereof, and means responsive to the fuel delivery pressure at said introducing means'for controlling said displacement varying means.

3. In an aircraft fuel supply system, means adjacent the aircraft engine for introducing fuel therein, a tank adapted to hold a supply of volatile fuel, said tank being locatedat a point remote from said introducing means, a fuel'line extending from said remotely located tank to said introducing means, the combination therewith of maneuvering the aircraft as well as for effects resulting from the relative locations of said tank and said introducing means, said pumping system comprising a first pump located at a point in said line between said 'tank and said introducing means and remote from said fuel introducing means, a liquid responsive motor drivingly connected to said fuel pump, a second pump located adjacent and arranged to be driven by said aircraft engine, said second pump being particularly characterized by the provision of means for varymg the displacement thereof, means for placing said displacement varying means in communication with the fuel delivery pressure at said introducing means, means defining a closed liquid circuit connecting said second pump and said liquid motor including a relatively non-volatile liquid power transmitting means, whereby pressure in the fuel introducing means is effective to vary the displacement of said second pump to cause the same to deliver a varying supply of power transmitting fluid to said motor with the result that said fuel pump is caused to deliver a substantially constant pressure of fuel to said introducing means.

4. In a fuel supply system for aircraft motors including means adjacent said motor for intro ducing fuel therein, volatile fuel storage means located at an elevation below that of said introducing means, and means for moving said volatile fuel from said storage means to said introducingd means located thereabove while maintaining the pressure to which said volatile fuel is subjected above a predetermined critical minimum value for preventing the introduction therein of vapor bubbles, said means comprising a constant displacement rotary volatile fuel pump located at substantially the level of said storage means and in communication with'the volatile fuel contained therein, said pump being effective to receive and force said fuel above the level of the pump to said introducing means, a constant displacement liquid pressure responsive rotary motor for driving said fuel pump, a second rotary liquid pump driven from said aircraft engine, means defining a closed liquid pressure power transmitting circuit connecting said second pump and said liquid motor, said circuit including a relatively non-volatile liquid, said second pump being an adjustable eccentricity variable displacement pump and comprising a rotor having a fixed axis, an embracing sleeve received about said rotor carrying reciprocable vanes and being eccentrically adjustable relative to said rotor, means for adjusting said eccentricity comprising means defining a chamber adjacent said rotor, a disc-like diaphragm received in said chamber and dividing the same into a first and a second compartment, said diaphragm being connected about the periphery thereof to said housing and at the center thereof to said adjustable sleeve, means placing said first compartment in communication with the volatile fuel delivery pressure at said introducing means, and means placing said second compartment in communication with the output of said second non-volatile liquid pump whereby the resultant of the action of the pressure in said introducing means and the output pressure of said second pump is effective to adjust the eccentricity of said sleeve relative to said rotor for varying the speed of said first named volatile fuel pump to cause the same to deliver fuel at a constant pressure to said fuel introducing means.

5. In an arrangement for delivering volatile fuel from a remotely located storage means of ing the introduction into said fuel of vapor bubbles, said means comprising a constant displacement rotary vane type volatilefuel pump located at substantially the level of said remotely located storage means and in communication with the volatile fuel contained therein, conduit means leading from said fuel pump to said carburetor said fuel pump being effective to receive volatile fuel from said storage means and force the same through said conduit to said carburetor, a constant displacement liquid pressure responsive rotary motor for driving said fuel pump, means defining a closed liquid pressure power transmitting circuit for supplying said liquid motor, said circuit including a relatively non-volatile power transmitting liquid, a liquid pressure generator adapted to be driven by the aircraft motor comprising means defining a housing having an inlet, an outlet, a pumping assembly chamber disposed between said inlet and said outlet. a rotor in said chamber having a fixed axis of rotation, an embracing sleeve received about said rotor carrying reciprocable vanes cooperating with the inner periphery of said sleeve, said sleeve being eccentrically adjustable relative to said rotor, means for adjusting said sleeve comprising means defining a chamber adjacent said rotor, a disclike diaphragm received in said chamber divid- 4 ing the same into a first and second compartment, said diaphragm being connected about the periphery thereof to said housing and having means connecting the center thereof to saidadjustable sleeve, means placing said first compartment in communication with said volatile fuel being delivered to said carburetor for subjecting said first compartment and diaphragm to the delivery pressure of said volatile fuel, and means placing said second compartment and diaphragm in communication with the output pressure of said non-volatile liquid pressure generator, said last named means comprising a restricted passage defined between said housing and said connecting means between said diaphragm and said sleeve for admitting liquid pressure from the outlet side, of said generator to said second compartment, a second passage formed in said housing leading from said second compartment to the inlet side of said generator, a spring pressed ball check valve interposed in said last named passage and responsive to the occurrence of a predetermined pressure in said second compartment for placing said second compartment in communication with the inlet side of said generator, whereby to control the displacement of said generator in accordance with the pressure of volatile fuel delivery at said carburetor for maintaining said delivery pressure constant irrespective of variations in the rate of fuel consumption by the aircraft motor.

HOMER D. ROE.

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