US2291074A - Fuel feed system - Google Patents

Description

July 28,1942. F, LINT 2,291,074

FUEL FEED SYSTEM Original Filed July 15, 1959 2 Shegts-Sheet 1 INVENTOR FLOYD F.' FLINT ATTORNEY.

July 28, 1942. v F. F. FLINT 2,291,074

FUEL FEED SYSTEM Original Filed July 15, 1939 2 Sheets-Sheet 2 24 76 7/ 69 70 6'6 4; "74 37 a [I 2? 4 3 Q Z3-\ 56 44 7 9r @3 a2 /5 20 Z3; 7 V I a! I? g 40 354/ 65 93 a5 '25 26 Z5 F|G.4

FIG. 5

INVENTOR FLOYD F. FLINT ATTORNEY Patented July 28, 1942 FUEL FEED SYSTEM Floyd F. Flint, St. Louis, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a. corporation of Delaware Original application July 15 1939, Serial No. 284,691. Divided and this application October 24, 1939, Serial No. 300,952

Claims. (01. 103 150) This invention relates to pumping devices for supplying volatile fuels to internal combustion engines and is a division of an application Serial No. 284,691, filed July 15, 1939, now abandoned.

It is customary in present day automobiles to draw fuel from a remote low level tank and force it to the carburetor by means of a mechanical fuel pump having a reciprocating diaphragm which is positively actuated-in the charging direction by a one-way connection. to the engine cam shaftand in the discharging direction by a discharge spring. This arrangement maintains the pump discharge pressure fairly uniform under moderate conditions of temperature, fuel volatility, speed of operation, and changes in rate of flow at low operating speeds.

It has been found that these pumps, as now constructed, are limited in capacity and allow the pressure to fall, at higher speeds and flow rates, due to the inertia of the diaphragm and operating rod and link assembly which produces a lag in the diaphragm reciprocations. This lag is effective in varyingdegrees under substantially all running conditions and at speeds much above, two thousand strokes per minute results in substantially decreased pressure at the pump outlet, even when the fuel being pumped is free from vapor bubbles.

Another difficulty common to prior constructions is that when the engine becomes highly heated as after a fast run or when the atmospheric temperature is high, the fuel in the feed lines and pump frequently vaporizes, forming vapor bubbles in the fuel and,further reducing the efficiency of the fuel supply system, since vapor or gas in the system reduces the quantity of liquid fuel delivered per stroke and also because any vapor which surrounds the pump or occurs in the intake line valves may cause substantial loss in the efficiency of the pump, or even complete failure.

Under aggravated conditions of vapor formation, an elastic, gaseous bubble may form in the pump and feed lines, particularly anterior to the pump inlet check, which expands and contracts with the diaphragm pulsations and wholly pre-'- vents the pumping of fuel-a condition known as vapor lock.

The pump and fuel lines also may be excessively heated after the engine is stopped after a hard run, with the result that the pressure in the line between the pump outlet and carburetor may be increased, due to the formation of gas, to as much as seventeen pounds per square inch,

when stationary, should not be above four pounds per square inch. At the same time, boiling in the carburetor bowl lowers the fuel level therein, dropping the float and opening the needle valve. When this occurs, gasoline and vapor spurt into the bowl, due. to the high pressure behind the needle valve, excessively raising the nozzle into the intake manifold. This condition makes-restarting of the engine extremely difficult or impossible until the excess fuel is drawn out of the manifold and firing chambers.

I have found that the defects outlined above can be remedied and the efficiency of the fuel pump can be materially increased by reducing the weight of the parts moving with the diaphragm to a point at which the spring will cause the diaphragm torfollow the cam, and also by spacing the pump body considerably farther from the engine than has been the'ca'se heretofore and supporting the same by means of askeleton ized tube or housing which permits the circulaexhaust pipe will be first communicated to this cap of fuel which insulates the pump inlet chamber where boiling may cause vapor lock.

Accordingly, anobject of the present invention is to construct new, improved, exceptionally light diaphragm supporting structure for a fuel pump for internal combustion engines, and'in which the forces are applied to the diaphragm in such a manner as to permit the greatest reduction in the size of the operating parts.

Another object is to provide means for mounting an engine operated pump at a substantial distance from the engine and minimizing the transfer of heat fromv the engine through the pump mounting.

Another object is to construct a pump of the above type in which the pump diaphragm is operated wholly by linear forces acting in tension applied axially of the pump mounting which projects laterally from the engine and the diaphragm so that this mounting as well as the diaphragm operating parts may be made of subwhereas, the pressure produced by the fuel pump, 5 stantially lighter construction than would be the case if thepositive operating forces of the cam were applied in" compression to the diaphragm operating parts.

Another object is to arrange the diaphragm and its operating mechanism so that thediaphragm may beeasily and quickly replaced in case of injury thereto. I V Y Another object is to provide a novel diaphragm assembly for a fuel pump which may be inexpensively and durably constructed of relatively light materials.

Another object is tov provide novel means for preventing excessive heating of the fuel in the fuel pump and fuel supply lines. T

Another object is to provide aiuel pump in which the valves are positioned so as to be readily accessible for inspection and repair by merely removing the pump cover.

Still. another object is to provide shock ab which an inlet chamber of substantial capacity is provided and mountedat the lowerpart of the pump or at least at a part where it will absorb a; substantial amount of heat before reaching the boiling point, and, in doing so, will protect the suction and compression chamber from becoming heatedito a point where boiling would occur in sufllcient degree to cause vapor lock,

These objects andother objects hereafter appearing are attained substantially by thestructure illustrated :in'l the accompanying drawings in which like reference numeralsrefer to like parts: r r

Fig. l is a somewhat diagrammatic view showing portions of an internal combustionengine embodying the invention. i

Fig.2 is a top viewof the fuel pump with parts broken away for clearer illustration.

Fig. 3 is a vertical transverse section taken online 3-3 of Fig. 2. v

Figs. 4 and 5 are vertical sections taken on the corresponding section lines of Fig. 2.

Fig. 6 is a disassembled view showing the diaphragm assembly. ,7

Fig. 1 of the drawings shows an internal combustion engine IIl'having an intake manifold II mounting in the usual manner a carburetor I2 having a float controlled constant level chamber I2a. Also mounted on theengine below the level of the carburetor is a fuel pump, generally indicated at and connected to the carburetor constant. level chamber by a tube I4. 'Asecond tube I5 extends laterally and, rearwardly from the fuel pump to a remote fuel tank (not shown). The portionof tube I5 immediately adjacent the engine is surrounded by a' hollow casing I5 formed preferably of loom or other heat resistant material and closed at the outer end by a plug or cork II which forms a heat insulating dead air space around the tube.

The fuelpump is formed of a central body casting I8 having a horizontal partition I9 forming upper and lower chambers and 2| therein.

The upper chamber is closed by a dome-like cover 22 secured to a post 23 at the center of the body casting by bolt 24. A bowl 25,which is shown of metal, but which may be of glass, extends beneath and closes the lower chamber and is accured in position by a bolt 25. A screen 21 is in- I terposed between the upper edge of bowl. 25 and the attachingflange on the body casting and separates the bowl 25 fromthe lower or inlet chamber 2|. Cap 22,and bowl 25 are provided with sealing gaskets 25 and 20.

As shown in Fig. 4, inlet boss 3|, threaded for connection to 'tube I5, communicates through passage 22, having a right angle, vertical portion 25 at its inner extremity, with bowl 25.. Portion '35 of this passage is formed in a cup 54 extending axially below post 22 and surrounding but spaced from the upper part of bolt 25. Cup 54 opens through the center of screen 21. A passage extends through partition I5 and is surrounded above the partition by a wall 55 forming an inlet valve chamber 21. which communicates with pumpingchamber "through a port 55. Adisk inlet check 40 is normally :urged downwardly against its sea't 4| in chamber 51 by coiled spring 42 scatedtat its upper end against a cap 53 which closes the top of theinlet chamber. A' sealing gasket is inserted between cap lsand'valve chamber wall 55; Cap 45 is threaded onto the upper extremity of post and is secured inposition by a lock nut 45. Port extends through a. wall or partition 45 whichseparates the upper'and lower chambers 25 and 2| and valve chamber 31 from pumping chamber".

Also extending upwardly 'inioupper or.-outlet chamber" from partition I9 is a second cylindrical wall 5I(Figs.'2, 3, and 5) forming an outlet valve chamber 5| which is closed the bot tom to lower chamber 2 I in the body castingand connects with pumpingchamber'fl by means of passage 52 through partition 42. A disk outlet check valve 53 is normally urged downyardly against its seat 54 by a smallcoiledspring 55 also seated at the topagainst a portion of cap 52 which overlaps wall 55 forming inlet chamber '31. Outlet valve chamber 5| at the top opens into the upper or outlet chamber 22 of the pump body. As shown'in Fig. 3, a threaded outlet con.-

nection 55 is provided onthe body communicating with outlet chamber 20 for connection to line I4 leading to the carburetor.

Cap 43' is provided with. a pair of depending pintles 55 and 55 extending respectively into inlet valve spring 52 and outlet spring 55 for stabilizing the same.

The pump is supported from the engine by means of an elongated, skeletonized housing 5|,

flanged'as at H for attachment to the engine crank case adjacent cam shaft 52. The housing wall has substantial cut-away or recessed porti0ns'53 which minimize heat transmission from the engine to the pump body and permit circulation of cooling air therethrough an inspection 01 cured to asimilarly shaped flange 15 surround,

I ing pump chamber 38 by means of bolts or screws 18. A diaphragm ll of suitable gasoline resistant and durable material is clamped between flanges l4 and (Fig. 4). The diaphragm has a central perforation receiving a member 18 (Fig. 6) for connecting the same to a force transmitting tension wire 19 extending axially through housing 68. A pair of force distributing cups 88 and washers 8| are clamped on opposite sides of diaphragm 11 between a .shouldered portion 82 of member 19 and the spun over outer extremity 83 thereof. The inner portion of member 18 is cupped as at 84 and the bottom of the cup is further recessed as at 85 a depth slightly less than the radius of tension wire 79.

In assembling the diaphragm and wire, which is preferably a length of standard, cold-drawn wire of suitable composition and temper, a small collar 86 is inserted over one end of the wire which is then bent to a right angle asat 81 and inserted into recess 85 in member I8. Collar member 86 is then slid into cup 84 and the edges of the latter spun or pressed over so as to rigidly clamp the wire in its connected position. At the oppoiste end of wire 19 is a second force transmitting head member88 havin a cup 89 and recess 98 in its inner portion, the latter receiving bent over end portion 9! of wire 19. A small disk cap 92 is then placedin cup 89 and the edges thereof spun over 'so as to. rigidly clamp the wire in position. A bumper block 93 of rubber or other suitably resilient material is seated in a cup 94 formed in the outer face of head member 88. A fibre washer 95 is placed against the outer face of member 93 for engagement with arm 68 of operating crank 65.

Diaphragm 11 is constantly urged outwardly or in its discharging direction by a coiled spring 91 seated at its inner extremity against an annular shoulder 98 On the inside of housing 60. The

outer extremity of spring 91 seats against inner,

force distributing cup 80.

The arrangement of diaphragm tension wire 19 and operating crank 65 is such that the parts can be readily disassembled to permit removal of the diaphragm by merely driving out pivot pin 64 and withdrawin the crank. Ann 68 of the crank and abutment 88 on the tension wire, when assembled, are both positioned in a relatively large chamber at the inner end of supporting housing 60 so that these parts may be readily viewed by a mechanic to further facilitate assembly and disassembly.

In operation, cam 61 rotates with the engine, positively moving crank 85 in a counterclockwise direction every time the high point on the cam engages the crank, which movement, in turn,

through wire 19, draws diaphragm ll inwardly.

or in its charging direction against spring 19. This movement of the diaphragm increases the size of pumping. chamber 38 so as to draw fuel through inlet connection 3|, passages 32 and 33 into bowl 25 and thence through screen 21, and passage 35 past inlet check 40 and through valve chamber 31 and port 39 into the pumping chamber. As follower arm 66 on the operating crank engages the low point on the cam, spring 91 resiliently urges diaphragm 'I'l outwardly so as to close inlet check 40 and force fuel from the pumping chamber through passage 52 past outlet check 53 into the upper chamber of th pump body casting from whence the fuel passes through outlet connection 56 and tube M t the carburetor. Chamber 20 forms a gas dome for collecting gases and dampening pulsations. In case the carburetor needle valve is seated, sufficient pressure will be built up in pumping chamber 38 to prevent or limit expansion of spring 91 and thereafter crank 64 will oscillate without producing the full stroke of the diaphragm.

Since pumping forces are applied to the diaphragm axially of supporting housing and no bending forces are applied thereto, and since the operating force is transmitted through the member 19 in tension, the pump may be supported farther from the engine'and the supporting housing may be made substantially of lighter construction than is the case where pumping forces are applied to the diaphragm vertically or radially of mounting flange 15.

I have found that the novel, skeletonized housing 88 substantially limits the heat which passes from the engine to the body, even after the engine cooling system isstopped and the engine heat built up abnormally. As a matter of fact, in 7 actual tests I have found that after a-hard,-fast run of the engine, when the side wall of the engine and crank case is much too hot to be touched by the human skin without causing a severe burn, the hand may be held upon the pump body casting without pain. Thus the pump, at all times, will be substantially cooler than is the case with pumps now'generally in use which are closely mounted upon the side of the engine crank case and supported by a solid metal connection. One advantage of the cool' operating pump is in the substantialelimination of vapor lock which is caused by excessive heating of the pump body and adjacent fuel lines during operation causing gasification of the fuel therein. I have found that the pump herein described operates satisfactorily under conditions which it is known will cause gasification and vapor lock in the pumps now in general use.

The insulating casing l6 shown in Fig. 1 also materially contributes to the cool operation of the pump in that the gasoline entering the pump is found to be many degrees cooler than would be the case with the casing omitted.

Another reason for the elimination of vapor lock where my pump is used arises from the very light construction of they diaphragm assembly which substantially reduces the moment of inertia which, in turn, hasthe effect of increasing the capacity of the pump. Various factors limit the practical size of the pumping diaphragm and it has been found that in fuel pumps having relatively heavy driving rods and portions of the operating linkage connects thereto the discharge capacity drops off rapidly at speeds of around 2000 reciprocations per minute, due largely to the inability of a diaphragm to follow the pulsations of the operating armi. I- have found that by using a relatively light tension wire to apply charging movement to the diaphragm, the moment of inertia of the diaphragm assembly can be cut appreciably and the capacity of the pump at the higher speeds correspondingly increased. Thus, the pump described can function satisfactorily even though substantial gas is present in the pumped'fuel, having suflicient capacity to pump liquid fuel with the gas.

Due to the cool operation of the pump, I also find that after the engine is stopped and gasification occurs in thecarburetor and fuel line between the pump and carburetor, condensation of these gases will occur in the pump within a very few minutes after the engine is stopped although,

ordinarily in hot. weather the temperature of the engine does not reach its peak until five or ten 4- minutes after the engine is stopped. This condensation has the effectof reducing the pressure in the system so as to effectively counteract pressure build-up in the fu'elconnection to the carpump is used there is. practically no build-up. and, in some cases, there is actually a negative pressure in the connecting-line to the carburetor due to the rapid condensation in the pump. The strength andweight of tension wire'lS are of extreme importance. I have found that wire manufacturers are able to produce wire of .080' of .100 inch thickness which is light, yet suffi-,

ciently strong to withstand theforces applied thereto. Bumper 93 tends to deaden the pounding. of the wire by the operating arm and thus increases the durability. thereof. V t

It will be noted that. the cover 22 covers a pocket or cap of substantial size containing fuel which has passed the outlet valve 5| of the pump. This cap of fuel is between the suction chamber of the pump and the exhaust pipe 99 of the engine, and therebyforms a protection for the suction chamber of the pump from the heat radiated.'from the exhaust pipe. The chamber also protects the suction chamber from overheating. chamber 25 isof substantial capacity containing enough fuel, which is fresh from the comparatively cool main tank, to substantially increase the amount of heat which must be transmitted from, the exhaust pipe and other heated portions of the engine 'to the suction chamber of the pump before boiling can'occur therein. In short, I have protected the suction chamber of my pump in two ways. First, by interposing a fuel cap between the suction chamber and the main source of heat and, second,

by nountingv a substantial quantity of compara tively cool fuel in contact with the lower side of the suction chamberso as to absorb the heat to a phragm and permanently secured at one end' tion elementhaving a recess, a tension wire having a diameter on the'order of .080 to .100 inch and witha relatively short, bent-over end portion positioned in' said recessfa cap element received on said wire inwardly of said bent over portion and securing the same rigidly in said recess, and a second force transmittingelement at theopposite end of said wire.

2.,A pump diaphragm'assembly unit compris ing -a' diaphragm of flexible, durable material, a ten'siori'wire projecting axially from said diathereto, a force transmitting enlargement received onfsaid wire'adjacent the opposite end and having a recess, saidwire having a bent-over extremity in said recess, anda plug elementse cured in said're'cess and rigidly clamping said bent-over extremity therein. g

, 3. Aefuel feedingdevlce as specified in claim'z in which said enlargement has a substantial flat surface adjacent said bent-over wire x m y and a non-metallic bumper on said surface.

'4. In a fuel feeding device, apumpincludinga bodyand a reciprocable pumping member,-a pump supporting structure projecting from said pump, an operating member adjacenta portion of said supporting structure ,spacedjfrom said pump,,a relatively light tension wireextending substantially from said'p'umping member to said operating member and spaced throughout its length from said body, connectingelementsse- I cured to the ends of said wire, one or; said connecting elements being secured to said pumping substantial degree as theheat is received from 1. A pump diaphragm assembly unit comprising a diaphragm of flexible, durable material, a force transmitting connection element including discs on opposite sides of said diaphragm and a part permanently securing thesameand'said diaphragm in fluid tight assembly, said connecmember-and the other being positioned to be movedin one direction by said operating member to move said wire and pumping memberin said direction, said connecting elements being only of sufficient length for'connecting said pumpingand operating members to said wire, and spring means for operating said wire and pumping member in the other direction. v Q

5. In a fuel feeding device for an internal come bustion engine, a chambered structure having an open ended; part for attachment to an internal,

combustione'ngine, an operating'lever having a readily detachable, pivotal mounting on said part,

a pumping element spaced along said structure from said part, said lever having an arm projecting outwardly beyond said structure for engagement'witha movable engine part and a second, recessed arm within said open ended part,

and a relatively small tension wire Permanently secured tosaid. pumping element and having a force transmitting enlargement normally positioned in said; open ended part and detachably assembled with said recessed arm for one way movement thereby, said enlargement and said recessed arm, in their assembled positions, being readily visiblefrom outside-said open ended part and there being vsuflicient space provided; inside said open ended part to facilitate disassembly and re-assembly of said operating lever and. wire.

FLOYD F. FLINT

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