US2288347A - Fuel feed system - Google Patents

Description

June 30, 1942. F. F. FLINT 2,288,347

' FUEL FE'ED SYSTEM Original Filed Oct. 24, 1939 2 Sheets-Sheet l INVENTOR FLOYD F. FLINT @M ATTORNEY June 30, 1942. F. F. FLINT 2,288,347

FUEL FEED SYSTEM Original Filed Oct. 24, 1939 2 Sheets-Sheet 2 1 6? 6'6 24 Y 7 70 K V 4 \r74 22 37 P9 4 4 64 Q a1 a0 3 I7 35 a4 0 78 61 25 Z6 Z5 F|G.4

II I? i I 1- 2/ 76 l F|G.5

INVENTOR FLOYD F. FL|NT QWJJ u ATTORNEY Patented June 30, 1942 FUEL FEED SYSTEM Floyd 1. Flint, St. Louis, 110., anignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Original application October 24, 1989, Serial No.

1940, Serial No. 347,825

2 Claims. (CL 103-228) This invention relates to pumping devices for supplying volatile fuels to internal combustion engines.

This is a division of my co-pending application Serial No. 300,952, filed October 24, 1939.

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 shaft and 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. I

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 varying degrees 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. It is impractical to increase the strength of the discharge spring enough to force the diaphragm to follow the cam, because ruptures of the diaphragm would result.

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 efliciency 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 volumetric 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 which expands and contractswith the diaphragm pulsations and wholly prevents 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 as Divided and this application July 27,

after a hard run, with the result that the pressure in the line between the pump outlet and carburetor may beincreased, due to the formation of gas, to as much as seventeen pounds per square inch, whereas, the standing pressure produced by the fuel pump alone 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 diflicult 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 to follow the cam, and also by spacing the pump body, considerably farther from the engine than has been the case heretofore and supporting the same by means of a skeletonized tube or housing which permits the circulation of cooling air therethrough and minimizes the transfer of heat to the pumping chambers.

I have further improved the resistance of my fuel pump to the formation of vapor look by arranging the inlet and outlet chambers so that the upper part of the pump which is adjacent the main source of radiation heat, to wit, the exhaust pipe, is filled with fuel which has passed the outlet valve of the pump. This fuel forms a cap of fuel over the inlet or suction chamber of the pump so that heat radiated from the exhaust pipe will be first communicated to this cap of fuel, and any boiling which may occur merely builds up pressure in the discharge line to the carburetor. As soon as the engine starts to run, the carburetor float valve opens and relieves this pressure so that less harm is done than if the boiling should occur in the suction chamber of the pump, in which case the pump would become vapor locked and refuse to function at all.

Accordingly, an object 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 from 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 substantially lighter construction than would be the case if the positive 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 the diaphragm may be easily and quickly replaced in case of injury thereto.

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 to provide novel means for preventing excessive heating of the fuel in the fuel pump and fuel supply lines.

Another object is to provide a fuel 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 absorbing means for diaphragm operating mechanism so as to permit reduction in size and strength of this mechanism.

Another object of the invention is to construct a fuel pump in which the suction and compression chamber is protected from the main source of heat by a cap of fuel which has passed through the exhaust valve and can no longer afiect the ability ofjthe diaphragm to draw in fresh fuel on itssuction stroke.

Another object of the invention is to provide a pump of the above described character in which an inlet chamber of substantial capacity is provided and mounted at the lower part of the pump or at least at a part where it will absorb a substantial amount of heat before reaching the boil ing point, and, in doing so, will protect the suction and compression chamber from becoming heated to a point where boiling would occur in sumcient degree to cause vapor lock.

These objects and other objects hereafter appearing are attained substantially by the structure illustraated in the accompanying drawings in which like reference numerals refer to like parts:

Fig. 1 is a somewhat diagrammatic view showing portions of an internal combustion engine embodying the invention.

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

Fig. 3 is a vertical transverse section taken on line 3-3 of Fig. 2.

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.

Fig. 1 of the drawings shows an internal combustion engine it] having an intake manifold M mounting in the usual manner a carburetor l2 having a float controlled constant level chamher 92a. Also mounted on the engine below the re level of the carburetor is a fuel pump, generally indicated at it and connected to the carburetor constant level chamber by a tube M. A second tube l5 extends laterally and rearwardly from the fuel pump to a remote fuel tank (not shown). The portion of tube i5 immediately adjacent the engine is surrounded by a hollow casing it formed preferably of loom or other heat resistant material and closed at the outer end by a plug or cork H which forms a heat insulating dead air space around the tube.

The fuel pump is formed of a central body casting It having a horizontal partition l9 forming upper and lower chambers 20 and El therein. The upper chamber is closed by a dome-like cap 22 secured to a post 23 at the center of the body casting by bolt 2%. A bowl 25, which is shown of metal, but which may be of glass, is placed under and closes the lower chamber and is secured in position by a bolt 26. A screen 2? is interposed between the upper edge of bowl 25 and the attaching flange 25 on the body casting and separates the bowl 25 from the lower or inlet chamber El. Cap 22 and bowl 25 are provided with sealing gaskets 29 and Fill.

As shown in Fig. 4, inlet boss 3!, threaded for connection to tube i5, communicates through passage 32, having a right angle, vertical portion 33 at its inner extremity, with bowl 25. Portion 33 of this passage is formed in a cup 341 extending axially below post 23 and surrounding but spaced from the upper part of bolt 26. Cup 36 opens through the center of screen H. A passage 35 extends through partition l9 and is surrounded above the partition by a wall 36 forming an inlet valve chamber 37 which communicates with pumping chamber 38 through a port 39. A disk inlet check (l0 is normally urged downwardly against its seat M in chamber 37 by coiled spring 62 seated at its upper end against a cap 63 which closes the top of the inlet chamber. A sealing gasket M is inserted between cap 63 and valve chamber wall 36. Cap 13 is threaded onto the upper extremity of post 23 and is secured in position by a lock nut 35. Port 39 extends through a wall or partition 36 which is an extension of body casting l8 and separates the upper and lower chambers 28 and 2i and valve chamber W from pumping chamber 38.

Also extending upwardly into upper or outlet chamber 20 from partition is is a second cylindrical wall 5t (Figs. 2, 3, and 5) forming an outlet valve chamber 5l which is closed at the bottom to lower chamber 2! in the body casting and connects with pumping chamber 38 by means of passage 52 through partition (12. A disk outlet check valve 53 is normally urged downwardly against its seat 54 by a small coiled spring 55 also seated at the top against a portion of cap 63 which overlaps wall 36 forming inlet chamber 37. Outlet valve chamber 5i at the top opens into the upper or outlet chamber 29 of the pump body. As shown in Fig. 3, a threaded outlet connection 55 is provided on the body communicating with outlet chamber 20 for connection to line M leading to the carburetor.

Cap 03 is provided with a pair of depending pintles 58 and 59 extending respectively into inlet valve spring 32 and outlet spring 55 for stabilizing the same.

The pump is supported from the engine by means of an elongated, skeletonized housing til, flanges as at ti for attachment to the engine crank ease adjacent cam shaft 62. The housing wall has substantial cut-away or recessed portions 03 which minimize heat transmission from the engine to the pump body and permit circulation of cooling air therethrough and inspection of the enclosed mechanism. Pivoted at 64 in the housing is an operating bell crank 65 having an arm I. forming a follower for operating the pump from cam 01. Crank 8! has a second curved arm 68 for transmitting motion to the pump diaphragm assembly, to be described. A-coiled spring 60 is compressed between a finger I rigid with crank I and the bottom of a cup Ii formed on the upper portion of housing 80 and constantly urges follower arm against cam 81.

Formed on the outer extremity of supporting housing 60 is a circular flange 14 which is secured to a similarly shaped flange I! surrounding pump chamber 30 by means of bolts or screws 16. A diaphragm ll of suitable gasoline resistant and durable material is clamped between flanges 14 and 1! (Fig. 4). The diaphragm has a central perforation receiving a member ll (Fig. 6) for connecting the same to a force transmitting tension wire II extending axially through housing 60. A pair of force distributing cups '0 and washers II are clamped on opposite sides of diaphragm I1 between a shouldered portion 82 of member I! and the spun over outer extremity 83 thereof. The inner portion of member 18 is cupped as at N and the bottom of the cup is further recessed as at 85 a depth slightly less than the radius of tension wire 19.

In assembling the diaphragm and wire, which is preferably a length of standard, cold-drawn wire of suitable composition and temper, a small collar 06 is inserted over one end of the wire which is then bent to a right angle as at 81 and inserted into recess ll in member 10. Collar member 86 is then slid into cup II and the edges of the latter spun or pressed over so as to rigidly clamp the wire in its connected position. At the opposite end of wire I! is a second force transmitting head member 08 having a cup 89 and recess 80 in its inner portion, the latter receiving bent over end portion SI of wire 19. A small disk cap 92 is then placed in cup 09 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 04 formed in the outer face of head member II. A fibre washer ll is placed against the outer face of member 91 for engagement with arm 68 of operating crank 65.

Diaphragm 11 is constantly urged outwardly or in its discharging direction by a coiled spring 01 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 I! 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 withdrawing the crank. Arm 58 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 01 rotates with the engine, positively moving crank 65 in a counterclockwise direction every time the high point on the cam engages the crank, which movement, in turn, through wire ll, draws diaphragm 11 inwardly or in its charging direction against spring 19. This movement of the diaphragm increases the size of pumping chamber 30 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 armBG on the operating crank engages the low point on the cam, spring 81 resiliently urges diaphragm l1 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 20 of the pump body casting from when the fuel passes through outlet connection 56 and tube It to the carburetor. a gas dome for collecting gases and dampening pulsations. In case the carburetor needle valve is seated. suflicient pressure wlil be built up in pumping chamber 38 to prevent or limit expansion of spring 91 and thereafter crank 6| will oscillate without producing the full stroke of the diaphragm.

Since pumping forces are applied to the diaphragm axially of supporting housing 60 and no bending forces are applied thereto, and since the operating force is transmitted through the member 18 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 I5.

I have found that the novel, skeletonized housing 60 substantially limits the heat which passes from the engine to the body, even after the engine cooling system is stopped and the engine heat built up abnormally. As a matter of fact, in 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, wil1 be substantially cooler than is thecase 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 substantial elimination 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 by pump is used arises from the very light construction of the diaphram assembly which substantially reduces the moment of inertia which, in turn, has the 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 arm. I have found that Chamber 20 forms by using a relatively light tension wire to apply charging movement to the diaphrgm, the mo ment 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 i present in the pumped fuel, having sufficient 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 the carburetor 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 minutes after the engine is stopped. This condensation has the efiect of reducing the pressure in the system so as to effectively counteract pressure build-up in the fuel connection to the carburetor needle valve. I have found that whereas with a standard type of fuel pump, as now generally used, there may be a pressure build-up of as high as 17 pounds per square inch in the line between the pump and carburetor within ten minutes after the engine has stopped, where my pump 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 and weight of tension wire 79 are of extreme importance. I have found that wire manufacturers are able to produce wire of .080

to .100 inch thickness which is light, yet sulficiently strong to withstand the forces applied thereto. Bumper 93 tends to deaden the pounding of the wire by the operating arm and thus increases the durability thereof.

It will be noted that the cap 22 covers a pocket of substantial size containing fuel which has passed the outlet valve of the pump. This cap of fuel is between the suction chamber of the pump and the exhaust pipe 99 of the engine, and thereby forms a protection from the suction chamber of the pump from the heat radiated from the exhaust pipe. The chamber 25 also protects the suction chamber from overheating. This chamber 25 is of 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 mounting a substantial capacity of comparatively cool fuel in-contact with the lower side of the suction chamber so as to absorb the heat to a substantial degree as the heat is received from other sources.

In general, the improved operation of my pump is due to its improved construction and mounting of the pump body and diaphragm assembly, in particular, whereby the pump operates much cooler than previous pumps and has greater capacity. Various features may be modified as will occur to those skilled in the art and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. In a fuel pump, a body member having horizontal and side walls, a detachable cover secured to the upper part of said body and forming a pressure accumulating outlet chamber with the same, an outlet connection for said chamber, a settling bowl on the lower portion of said body and forming an inlet chamber therewith, an inlet connection for said inlet chamber, a reciprocable pumping element secured to the side of said body and forming a pumping chamber with said side wall thereof, a passage connecting said inlet and pumping chambers and having a portion extending into said outlet chamber forming a first valve chamber, a second passage extending from said pumping chamber and having a portion forming a second valve chamber opening into said outlet chamber, an upwardly facing valve seat in each of said valve chambers, a check valve on each of said valve seats, a plate element secured in said outlet chamber across said valve seats and sealing said first valve chamber from said outlet chamber but only partially covering the connection between said second valve chamber and said outlet chamber, and valve springs compressed between said plate element and said valves, said plate element being readily removable through said outlet chamber upon removal of said cover to facilitate access to and removal of said valve and spring without necessarily disturbing said seat.

2. In a fuel pump, a body having partition structure therein forming liquid receiving chambers in the upper and lower parts thereof and a pumping chamber, liquid connections for said first-mentioned chambers and a removable cover for said upper chamber, passages extending respectively from said upper and lower chambers into said pumping chamber, said passages having laterally disposed portions extending into said upper chamber, upwardly facing valve seats in the mentioned portions of said passages, valves on said seats, a plate detachably secured over the mentioned portions of said passages, and valve springs between said plate and said valves, the assembly being arranged to facilitate access to said valves by removal of said cover and said plate, said plate, when assembled, sealing the opening between said upper chamber and the passage directly connecting said lower and said upper chambers, space being provided in the passage between said pumping and upper chambers whereby said upper chamber receives liquid from said pumping chamber during operation.

FLOYD F. FLINT.

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