US1415162A - Fuel-feed system - Google Patents

Description

F. E. EDWARDS.

FUEL FEED SYSTEM.

APPLICATION FILED MAY 24. I918.

Patented May 9,1922.

3 SHEEI'SSHEET- I.

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F. E. EDWARDS. FUEL FEED SYSTEM.

APPLlCATlON HLED MAY 24, 1 918.

Patented May 9, 1922 3 SHEETS-SHEET 2- F. E. EDWARDS.

FU'EL FEE D SYSTEM. APPLICATION FILED MAY 24. 1918.

QSHEETS-SHEET 3.

- 1A1 5 1 620 Patented May 9, 19220 5? 5906 2 b6 /g2 55 541 a u UNITED STATES PATENT OFFICE.

FRANCIS EDWIN EDWARDS, OF CHICAGO, ILLINOIS, ASSIGNOR T STROMBERG MOTOR DEVICES COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

FUEL-FEED SYSTEM.

Specification of Letters Patent,

' Application filed May 24, 1918. Serial No. 236,271.

To all whom it may concern:

Be it known that I, FRANCIS EDWIN En- WARDS, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Fuel-Feed Systems, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawinfi, forming a part of this specification.

y invention relates to fuel feed systems for automobiles and the like.

The present invention is an improvement over the invention-s disclosed in my co-pending applications Serial Number 204,484 filed November 30th, 1917 and Serial Number 217,701 filed February 16th, 1918.

Fuel feed systems, as applied to automobiles, trucks, and other types of engine driven vehicles, are provided for feeding the liquid fuel from the supply tank to the carburetor of the internal combustion engine. Heretofore, the majority of such systems have operated in one of three Ways, namely, by gravity, by pressure, or by suction. As the name implies, the gravity feed system relies upon a gravity head for feeding the fuel, this head being obtained by disposing the supply tank in an elevated position. This system is rapidly becoming obsolete, particularly in pleasure cars, due to the general design of the modern automobile body, which is unsuited to this elevated disposal of the tank. 35

.Pressure feed systems operate under the pressure of'a volume of compressed air onclosed in the supply tank, which tends to force the liquid fuel to the carburetor. These systems possess advantages over gravity feed systems, but they also are objectionable, due to the difliculty and theattention required to -maintain' the proper pressure in the tank,

and due to the fact that this accumulated pressure is lost when the tank is opened for refilling, and also due to the inadvlsabllity of keeping a large quantity of gasoline under pressure.

Suctionfeed systems have largely superseded both the gravity and pressure feed systems, due to the fact that they require neither an elevated tank nor a constantly maintained pressure in the tank. These systems operated upon a siphon system by sucking the fuel out of the supply tank and raising it to the carburetor or to an auxiliary tank above the carburetor by suction obtained from the intake manifold or from the carburetor itself. The suction feed system, is, however, subject to the disadvantage that it interferes with carburation and that on wide open positions of the throttle the suction in the intake manifold is often insuflicient to insure operation of the system.

As .the'basis of my invention I provide a column of compressible fluid, namely air. As the second element, I provide means for alternately compressing and rarefying this column of air, preferably a valveless impulse pump or pulsometer driven by the engine. This column of pulsating air is enclosed in part in a chamber which I broadly term the pumping chamber and which may consist of the impulse pump cylinder or an independent chamber connected to' the impulse pump. The pumping chamber is provided with inlet and outlet ports controlled by suitable valves, which ports have communlcation with the supply tank and with the carburetor float chamber, respectively.

The displacement of the pump itself is but a fractional part of the volume of the pumping chamber, the remaining volume being occupiedby the compressible air column and the incompressible body of liquid fuel.

In normal operation the rarefaction stroke of the impulse pump will first create a subatmospheric pressure on the pumping chamber suflicient to raise the fuel from the supply tank, after which the fuel will flow into the chamber to fill the volume displaced by the pump piston and at-the end of the stroke the pressure of the air column will be slightly below atmospheric pressure. On the compression stroke the pressure of the air column will rise above atmospheric pressure, sufficient to develop head enough to discharge the fuel to the carburetor float chamber and at'the end of the stroke will be slightly above atmospheric pressure.

Theoretically if no liquid were pumped the curve of pressure would be a sine wave fluctuating regularly above and below at mospheric pressurefor each cycle or revolution. The intake and discharge of'the liquid modifies the theoretical curve in two respects. The lag of the liquid causes the pressure curve to lag behind the pump stroke and restriction of the outlet causes the curve to rise above the neutral axis.-

This operation of alternate intake and expulsion will continue until the fuel from the pumping chamber is stopped by the float controlled valve in the constant. level chamber of the carburetor. The fuel will continue to flow into the pumping chamber temporarily on the rarefaction impulses and accordingly the level therein will rise. As this level rises the volume occupied by the air column will decrease, the liquid fuel being incompressible, and as the quantity of air remains substantially constant, the pressures of the column will increase. The compression pressures will rise considerably above atmospheric and the rarefaction pressures will approach atmospheric. When the rarefaction impulses reach pressure there will be no rarefaction, relatively speaking, and consequently there will be no flow from the supply tank.

The pulsating air column will continue to pulsate with the entire curve of pressures, above, or substantially above, atmospheric pressure and thus there willbe no pumping action of the pumping chamber. Between the piston of the impulse pump and the incompressible body of liquid fuel in the pumping chamber there is thus always interposed a cushioning column of air which absorbs the stroke of the pump during nonoperative periods and prevents positive ejection of the liquid fuel. V

In my two prior applications I secure the above action of shutting off the pumping chamber through the provision of a float controlled valve in the pumping chamber, which 'is operated by the fuel level therein to either close the fuel inlet or the pump connection to the pumping chamber or open an atmospheric inlet to the chaniber.

In the present invention I have obtained a greatly simplified construction by dispensing with this float valve in the pumping chamber. I prevent the continued intake of fuel byeither utilizing the elasticity of the pulsating air column to shorten or discontinue the pumping stroke, as above described or by increasing the volumetric capacity and decreasing the pressure pulsations in the pumping chamber by valve mechanism controlled by the liquid fuel level in the carburetor float chamber.

The manner in which I attain this oper ation will be more apparent from the fol lowing detailed specification taken in connection with the accompanying drawings, in

which I have illustrated one preferred em-.

bodiment of my invention,

In the drawing:

Figure 1 is a diagrammatic lay-out of my improved fuel feed syetem showing the air impulse pump construction;

atmospheric- Figure 2 is a vertical cross-sectional view of the pumping chamber;

Figure 3 is a plan'view of the same;

Figure 4 is a vertical cross-sectional view of dthe modified form ofpumping chamber; an

Figure 5 is a diagrammatic view of a modified form of my invention.

In Figure 1, I have shown my improved fuel feedsystem arranged to supply liquid fuel to the carburetor of an internal combustion engine. The invention is not limited to this use, however, as it may be employed for feeding oil to a liquid fuel burner or for lubricating bearings or other purposes.

The carburetor 1 supplies the hydro-carbon mixture to the internal combustion engine (not shown), the liquid fuel passing through the carburetor from a reserve supply contained in the float chamber 2. As 1 the fuel is used from the float chamber 2 it is replenished from the main tank 3 by the operation of the pumping chamber 4. This pumping chamber has connection through a pipe 5 with a pulsating air pump 6, which is driven by the engine.

The pulsometer 6 comprises an air cylinder 7 formed integral with a bracket 8 which is suitably bolted to the engine structure. A piston 9 is reciprocated in the cylinder 7 by a connecting rod 11 engaging with aneccentric 12 which is keyed to one of the operating shafts 13 of the engine, such as a cam shaft or the magneto shaft. The top of the cylinder 7 is closed by a cylinder head 14 threading down over the end of the cylinder. It will be noted that there are no valves in the cylinder or head, the sole function of the pump being to produce pressure oscillations whereby the column ofair in this pipe and in the pumping chamber 4 is alternately compressed and rarefied. The pipe 5 communicates with the interior of the pumping chamber 4 through a boss 15 formed integral with the cover 16. This cover is arranged to fit tightly upon the casing 4 to prevent any leakage of air into the chamber. The cover 16 has an extending lug 17 provided for supporting the pumping chamber from the carburetor as by bolting to the bottom of the screening shell 18, at the bottom of the float chamber 2. The inlet port of the pumping chamber 4 is connected to the main supply tank 3 through the pipe'19, and the outlet port is connected to the inlet of the float chamber through the pipe 21.

Referring to Figure 2 the chamber 4 is formed with a lateral extension 22, which is bored out to provide the valve cage 23' and outlet port 24, Which have communication with the interior of the chamber by wayof the cored passageway 25. A valve 26 is arrangedto seat upon the outlet port 24 and is confined in its movement in the valve cage 23 by a screw plug 27 threading therein. The outlet side of the valve cage 23 communicates through the bore 28 with the discharge pipe 21.

The intake pipe 19 threads into a screen'- ing shell 29 having inlet communication with the bottom of the pumping chamber 4, as illustrated in Figure 4. A plug member 31 threads axially into a conical enlargement 32 formed on the bottom of the casing 4. This plug member has an axial bore 33 forming an inlet port 35 opening into the pumping chamber and has radial ports 34 aflording communication between this axial bore and the interior of the shell 29. A radial flange 36 on the plug member bears against the conical enlargement 32 and a hexagonal nut 37 threading onto the endof the plug member, clam s the shell 29 against the enlargement 32. n annular straining screen 38 encircles the plug member 31 and is confined between the flange 36 and the bottom of the shell 29. A valve 39 normally seats upon the inlet port 35 and is guided in its opening movement by a cage device 41. It is of course understood that the float chamber 2 of the'carbu'retor has the usual float 42 and float valve mechanism 43 for maintaining a predetermined liquid level therein, as is well understood by those skilled in the art.

The operation of this embodiment of the fuel feed system is as follows:

As soon as the engine is turned over the piston 9 in the air impulse pump reciprocates, thereby generating in the column of air contained in the pump cylinder the pipe 5 and the chamber 4, alternate compressions and rarefactions. On the down stroke of the piston 9 the air in the pumping chamber becomes rarefied and drops below atmosheric pressure, thereby creating a suction 1n the pumping chamber. The initial stroke of the impulse pump sucks the air out of the pipe line 19 and expels it up through the float chamber 2 of the carburetor. As soon as the liquid fuel reaches a level high enough to seal the passage 25 in the pumping chamber, it comes under the influence of the compression stroke ofthe impulse pump 6. The vompressed air in the pumping chamber created by the upward stroke of the piston 9, acts upon this body of fuel and expels a portion thereof into the float chamber 2. It will be apparent that the-impulse pump 6, the pipe 5 and the pumping chamber 4 constitute in effect a plunger pump having an elastic plunger, the rarefactions and compressions of which alternately intake and discharge liquid fuel from the pumping chamber 4. This action will continue until the float chamber 2 has been filled to its predetermined level, when the float valve mechanism 43 will operate to close the inlet to further entrance of fuel. --As soon as this I.

occurs the fuel level will rise in the pumping chamber 4, due to continued inflow of fuel on the rarefaction impulses in the pumping chamber. 7

As this level rises it will be apparent that the air space in the pumping chamber will decrease in volume. -As the volumetric capacity of this air space decreases, the volumetric displacement of the impulse pump forms a larger, and larger proportion of the sum total of the reduced air column and consequently the pressures of the entrapped body of air will rise above normal value on both the compression and rarefaction strokes of the pump. Thereafter the elasticity of the reduced air column completely absorbs the stroke of the piston in the impulse pump and the pumping chamber will remain nonoperative until the fuel level falls in the float chamber. The non-operative condition of the pumping chamber will occur when the fuel level is some little distance below the cover 16 so that there will be no possibility of the fuel overflowing into the impulse pump 6.

To prevent any possibility of the mean pressure in the pumping chamber from ever falling so low that the above action would not occur, or that the compression impulses would be so low in pressure as not to stop the inflow of fuel on the compression strokes, I contemplate the provision of an atmospheric valve adapted to open and admit atmospheric pressure in limited amounts when the pressure in the pumping chamber reaches 'a predetermined minimum. As illustrated in Figure 4, the cover 16 is formed with an integral boss 44 internally threaded for the reception of the plug 45 and externally threaded to receive the cap nut 46. The plug 45 has an axial bore concentric with an enlarged bore in its lower end forming a valve seat 47 for co-operation with the needle valve 48. This needle valve is normally retained on its seat by weighted arms 49 pivoted on a depending portion of the cover 16 and bearing a ainst a flange on the end of the needle valve. hen the rarefaction impulses in the pumping chamber fa-ll below a-predetermined pressure, the valve 48 opens and atmospheric pressure enters through the apertures 51 in the cap nut 46. I employ the weighted arms 49 in preference to a spring to obtain a more reliable and accurate operation.

In Figure 5 I haveillustrated a modified arrangement wherein the level cont-rolled valve in the carburetor float chamber operates to open an air communication between the pumping chamber and the float chamber when the liquid level in the float chamber rises to a predetermined maximum. This results in a cessation of the flow of fuel into the pumping chamber due to the feebleness of the air impulses caused by establishing communication with the air space of the float chamber, which amounts to increasing the volumetric capacity of the pumping chamber. Furthermore, this operation vents atmospheric pressure into the system through the atmospheric port in the float chamber.

The air space in the top of the pumping chamber 4. has communication with the air space in the top of the float chamber 2' by Way of the pipe 52 which threads into the boss 53 on the cover of the pumping chamber, and extends up concentrically into the float chamber 2 as illustrated at 54:. A valve seat 55 is formed in the end of the pipe 54 and co-operates with the valve '56 in controlling the communication between the two chambers. The valve 56 is guided by a stem'extending through a member 57 on the top of the float 42'. The float 42 surrounds the stand-pipe'54and is guided thereby. A compression spring 58 is confined between the bridge member 57 and the valve 56 and retains the valve on its seat during periods of low-fuel level. When the level rises to its predetermined maximum the bridge member engages a bead 59 on the end of the valve stem and lifts the valve from its seat. In the present instance I have shown the discharge pipe 21 as opening into the top of the float chamber, thereby preventing the ebullition of the body of fuel in the float chamber when exhausting the air from the system through; the float chamber as previously described.

The normal operation of this system is similar to that previously described. When,

however, the fuel in the float chamber 2 rises to its definite level, the float 42' raises 6 the valve 56, thereby establishing communication between the pumping chamber and the float chamber. Thus the compression impulses from the impulse pump act upon the liquid areas in both ends of the pipe 21 equally, resulting in balanced pressures and a cessation of fuel flow into the float chamber. The pulsations of pressure in the pumping chamber are so enfeebled by thus increasing the capacity of the chamber relative to the impulse pump and by venting atmospheric pressure into the pumping chamber through the atmospheric port 62 in the float chamber, that the rarefaction impulses I claim:

1. In combination a receiving chamber, a pumping chamber 0 constant size having an inlet valve and an outlet valve for liquid, an air chamber enclosing a body of air and communicating with said pumping chamber, one wall of said air chamber being movable to produce compressions and rarefactions of said body of air, and valve means controlled by the level of liquid in the receiving chamber, for controlling the effective application of said compressions and rarefactions to said pumping chamber, said valve means shutting off the flow of liquid from the pumping chamber to the receiving chamber to cause the liquid to accumulate in the pumping chamber and thus cut down the effective volume of the air chamber.

2. In combination, a carburetor float chamber, a fuel pumping chamber of constant size having inlet and outlet valves for pumping fuel to said float chamber, said pumping chamber being below the level of the carburetor float chamber, a substantially closed air chamber enclosing a column of air and communicating with the top of said pumping chamber, one wall of said air cham-' ber being movable to produce compression and rarefactions of said column of air, and level sensitive means in one of said chambers for directly controlling the operation of part of said pumping chamber, said vent' having a check valve opening inwardly.

4. In combination, a pumping chamber of constant size having inlet and outlet valves for pumping liquid fuel or the like, a substantially closed air chamber enclosing a body of air communicating with the upper part of the pumping chamber, one wall of said air chamber being movable to produce compressions and rarefactions in said body of air, a vent opening in the upper part of said pumping chamber and a valve normally closing said vent, said valve adapted to open said vent to admit atmospheric pressure when the pressure of said body of air falls below a pre-determined minimum.

5. In combination, a source of liquid supply, a pumping chamber of constant size connected to said source, a receiving chamber connected to the pumping chamber, check valves governing said connections, an air chamber communicating with the top of the pumping chamber and enclosing a body of air, said air chamber having means to cause pulsations of suction' and pressure, and

means to limit the effective application of said pulsations, said means shutting off the gischarge of liquid from the pumping cham- 6. In combination, a pumping chamber of constant size havin inlet and discharge valves, an air impuie pumpconnected to the chamber and a carburetor float chamber communicating with the pumping chamber, said carburetor float chamber having a float controlled valve controlling the communication between the pumping chamber and the float chamber, closing of said float controlled valve causing an accumulation of liquid in the pumping chamber which raises the average pressure therein and prevents the suction of further liquid into the pumping chamber.

7 In combination, a pumping chamber of constant size having inlet and discharge valves, an air impulse pump connected to the chamber and a carburetor float chamber communicating with the pumping chamber, said carburetor float chamber having a float controlled valve controlling the'communication between the p'umpin chamber and the float chamber, closing 0 said float controlled valve causing an accumulation of liquid in the pumping chamber which raises the average pressure therein and prevents the suction of further liquid into the pumpfloat chamber controlling through the back pressure of the liquid the efiective application of the pulsometer to the pumping chamber.

'9. In combination, a carbureter chamber, a pumping chamber below said carbureter chamber, a delivery tube leading directly from said pumping chamber to said carbureter chamber, and means for interrupting the operation of said pumping chamber by interrupting the flow through said delivery tube.

In witness whereof, I hereunto subscribe my name this 21st da of May A, D. 1918.

FRANCIS E WIN EnwARns.

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