US2998056A - Carburetor fuel level control - Google Patents

Description

Aug. 29, 1961 L. R. CAPEHART CARBURETOR FUEL LEVEL CONTROL 2 Sheets-Sheet 1 Filed May 20, 1959 INVENTOR. [av/w! (405/427 Aug. 29, 196 R. CAPEHART CARBURETOR FUEL LEVEL CONTROL 2 Sheets-Sheet 2 Filed y 20, 1959 Fee 79509570? w M M M m My J 4 n ,n mmi i: l q, inwvi fiw m y i i m WI 5 i KA A VV, i m g 5 i 4, T m

I N V EN TOR. ZO/V/V/E 8 (hm-W427- BY W 2,998,056 CARBURETOR FUEL LEVEL CONTROL Lonnie Robert Capehart, 305 Standley Ave., Ukiah, Calif. Filed lVIay 20, 1959, Ser. N 0. 814,426 3 Claims. (Cl. 15836.3)

This invention relates to the field of internal combustion engines, and more particularly to fuel level controls for carburetors and other fuel metering devices.

One of the perennial problems associated with vehicles powered by internal combustion engines and more particularly with the carburetors thereof is that of metering the fuel supplied for just the proper air-fuel ratio for economical operation. When the air-fuel ratio is too lean, power developed by the internal combustion engine is insuflicient and, on the other hand, when the airfuel ratio becomes too rich flooding occurs with incident stalls, lurches, etc. The prior art has suggested many ways in which to overcome the problem of carburetor flooding, a problem particularly acute during the initial stages of starting an internal combustion engine. Even though numbers of solutions have been proposed, very few techniques have ever been successfully used to eliminate the propensities of conventional internal combustion carburetors to flood upon occasion. The poor fuel economy which results from improper fuel level control, not to mention the hard starting that result when too much gas is pulled into the carburetor which in turn worsens the condition to the point that the carburetor floods, provide adequate justification for the usefulness of the present invention,

The present invention envisions the use of an auxiliary tank or receptacle intermediate the carburetor, fuel pump and fuel storage tank which acts to prevent flooding from occurring in the carburetor. It is obvious, of course, that flooding not only occurs when starting a hot engine wherein gas fumes have expanded to cause a pseudovapor lock, but also arises when sudden acceleration or deceleration of the automobile causes the normally hori zontal level of gasoline in the carburetor bowl to assume a cant. Maneuvering on sharp curves or parking on hills has the same effect. When these external factors cause the level of gas in the carburetor to assume a non-horizontal level of disequilibrium, it causes the conventional float valve in a carburetor to be displaced from its plane of movement with the result that it does not seat properly. This allows gas to be pumped therein from the positive acting fuel pump. The result of this unwanted addition of gas from the fuel tank causes the carburetor bowl to become overfull with gasoline and flooding results.

The present invention overcomes the problem of flooding in internal combustion engine carburetors by providing a plurality of overflow orifices about the periphery of the carburetor bowl which act to drain ofl temporary excesses of gasoline resulting from vibration, sharp acceleration, deceleration and/ or parking on hills. In accordance with the present invention these orifices are placed about the carburetor 'bowl at least one of which is formed in the front side of the carburetor (with respect to the front of the automobile) and one in the rear side. With this arrangement, whenever sharp acceleration occurs, for example, the temporary high level of gasoline at the rear wall of the carburetor bowl flows through the overflow orifice and attached pipe. This lowers the level of the gas in the carburetor bowl and permits the float to open for compensatory pumping of gasoline from the fuel pump. After the acceleration levels out the carburetor approaches equilibrium and no further gas flows through the overflow pipes surrounding the carburetor bowl. The orifices and their overflow pipes are commoned into an auxiliary tank including an air vent and an auxiliary float mechanism, which tank apparatus co- 2,998,056 Patented Aug. 29, 1961 operates with the fuel storage tank and the fuel pump to recirculate the overflow of gasoline to the carburetor.

By using a plurality of orifices surrounding the circumference of the carburetor bowl, the principal deficiency in prior art flood prevention devices is obviated. A single overflow pipe is insuflicient since the direction of disequilibrium in the carburetor bowl is never predictable and varies depending on the cause thereof. Thus, by providing at least two or more annular displaced orifices close adjacent the normal equilibrium level of the gasoline in the carburetor bowl, any disequilibrium is bled into the auxiliary tank which permits the float in the carburetor bowl to permit the influx of gasoline to maintain the horizontal equilibrium position.

An object of the invention therefore is to provide a carburetor fuel level control which acts to prevent absolutely the conventionally float-operated carburetor from flooding. Other objects of the invention relate to an auxiliary tank readily adaptable to cooperate with existing internal combustion engines and their carburetor, fuel pumps and fuel storage tanks to simply, economically and effectively overcome flooding therein.

A feature of the invention pertains to the provision of a plurality of orifices angularly displace about the circumference of the carburetor bowl in float-operated carburetors.

Another feature of the invention pertains to an auxiliary tank cooperating with the plurality of orifices to temporarily store gasoline drained from the carburetor bowl in order to maintain a constant level therein. More particularly, this last feature includes an auxiliary tank having an auxiliary float valve operable to control the flow of gasoline from the fuel storage tank and the auxiliary tank to the fuel pump of the internal combustion system,

Yet "another feature of the present invention pertains to means cooperating with the auxiliary tank to prevent the exodus of gasoline therefrom through the air vent or through the overflow pipes connecting the carburetor to the auxiliary tank.

Still another feature of the invention pertains to the combination of a conventional internal combustion carburetor employing a float-valve metering device, a plurality of orifices formed about the circumference of the carburetor bowl and associated pipes for disequilibrium overflow, an auxiliary tank for collecting the overflow gasoline, float means associated with the auxiliary'tank for controlling a two-way control valve, a fuel storage tank, a fuel pump, and means connecting the fuel tank and the auxiliary tank to'the' fuel pump through the twoway valve whereby the source of gasoline pumped to the carburetor by the fuel pump is controlled.

In a more limited way, a feature of the invention pertains to an auxiliary tank combining a float actuated twoway control valve, filtering means, an'inlet and an air vent, and means cooperating with the inlet valve and air vent to prevent overflow from the axiliary tank into the atmosphere and carburetor systemp These and other objects and features may be more fully understood when the following detailed description is read with reference to the drawings, in which:

FIG. 1 is a schematic diagram of the carburetor level control constituting the present invention; and,-

FIG. 2 is a detailed schematic of the auxiliary tank forming part of the carburetor fuel level control of FIG. 1. 7

Considering the system as depicted in FIG. 1 first, it may be seen to include a float-controlled carburetor 10, an intake manifold 11, an auxiliary tank 12, a fuel storage tank 13, and a fuel pump 14-. The carburetor 10 is schematically represented and includes the float 15, having a valve assembly 16 thereon restrained in its vertical fuel , 3' movement (with respect to orientation of FIG. 1) by chain 17' which is afiixed to the bottom of the carburetor bowl of the carburetor 10. Gasoline is pumped from the fuel pump'14 through tube 18 into the top of the carburetor where it is metered into the carburetor 10 .by the valve 16 controlled by the level of the float The fuel pump 14' pumps gasoline from the auxiliary tank 12 and/or the'fuel tank 13 through pipe 19, as will be explained more fully below. A plurality of orifices or apertures a, 2%, etc., are formed about the periphery of the bowl of the carburetor 10 in a horizontal plane and at a height just suflicient to permit the valve 16 to prevent the flow of gasoline from tube 18' at the throat 21 without gasoline overflowing through the orifices 20. The orifices 20 are commoned through tubes 22 to the upper part of auxiliary tank 12 as illustrated. To complete the conventional part of the internal combustion engine carburetor system, the gasoline from the carburetor bowl flows through tube 23 into the intake manifold 11 where it is vaporized, combined and metered to the combustion chambers of the engine.

Looking to the operation of the carburetor 10 in conjunction with tubes 22 connected at their lower ends to the upper part of the auxiliary tank 12, it will be seen that whenever the automobile is at rest or running smoothly without sudden acceleration, deceleration, hill proximate the dotted line 25, assuming that the float valve permits enough gas to be pumped to compensate for the acceleration, per se. When the gasoline is displaced in this fashion, gasoline flows through the rear orifice 20a and overflow tube 22a to the auxiliary tank 12. Reduction of the level of gasoline in the carburetor 10 due to'the disequilibrium (ignoring the acceleration component) thereby lowers the level of the float 15 and opens the valve 16 further to permit the fuel pump 14 'to'pump additional gas therein. Since the level of fuel in the carburetor 10 has been decreased due to the disequilibrium, there is no possibility that the carburetor will flood, thereby causing the engine to stop or be hard to start. Naturally, the gasoline for the sudden acceleration is obtained principally from pump 14 as noted above. As soon as the cars momentum levels out and the level of gasoline again approaches the plane 24, the valve 16 reduces'the size of orifice 21 to the equilibrium maintaining fuel flow from the pump 14. In an opposite sense, if the car is suddenly decelerated or braked, the level of gasoline overcomes the forward or right orifice 20b and gasoline flows through the tube 22b to the auxiliary tank 12 with the same results noted above.

As gasoline flows into the auxiliary tank 12 through the tubes 22a, 225, etc., it passes through a check or backup valve 30 and ultimately causes the float 31 to rise to a point depending upon the level of the gasoline in the auxiliary tank 12. The float is connected to the two-way control valve 32 which cooperates with the fuel pump line 19 and the fuel tank line 33. As will be more particularly seen with respect to the details of FIG. 2, the two-way control valve 32 is arranged so that when a predetermined level of gasoline is obtained in the auxiliary tank 12, the lowerpassage 34 connecting the fuel tank and pipe 33 to line 19 and the fuel pump 14 is closed and the pump 14 pulls gasoline from the auxiliary tank 12 since the throat 35 of the upper part of the double check valve 32 is then opened. Contrariwise, until the level of gasoline in the auxiliary tank 12 is sufficient to push the float 31 upwardly 'far enough to close off the 4 throat 34, the throat 35 is closed off and all gasoline moved by the pump 14 is obtained from the fuel tank 13 via gas lines 33 and 19. The use of a two-way control valve in this manner permits the fuel pump 14 to obtain gasoline from the fueltank 13 until the level in the auxiliary tank 12 becomes sufficiently high to warrant bleeding off the gasoline collected therein. At

this time the fuel pump 14 transfers its source of suction to be separated from its throat 34.

from the fuel tank 13 to the auxiliary tank 12.

An air vent 36 is provided in the upper surface of the auxiliary tank 12 to permit free flow of the gasoline from the carburetor 10 into the auxiliary tank 12 and from there through the pump 14 back into the carburetor 10. The air vent 36 is provided with a check valve 37, which will be described in more detail below, to prevent gasoline from overflowing the tank 12" with the possible fire hazard and loss of gasoline. v

Recapitulating then briefly, the overall system can be seen to operate to assure that the level of gasoline in the carburetor bowl 10 is always at a more or less constant and equilibrium position. Whatever additional gasoline needs to be supplied to the carburetor 10 is supplied through the check valve 16 as a result of causing temporary overflow through the overflow tubes 22 whenever shifts in momentum cause the level to depart from the horizontal plane 24. Means are provided in the auxiliary tank 12 to cooperate with the two-way control valve 32 in order to permit the fuel pump 14 to draw gasoline alternately from the auxiliary tank 12 when the level therein becomes too high. Finally, means 38 is provided integral with the two-way control valve 32 in the auxiliary tank 12 to filter the gasoline flowing from the fuel tank into the double check valve 32 and thence through the fuel pump '14 to the carburetor 10. The filter 83'prevents malfunctioning of the control valve 32 due to the presence of small particles of dirt, sediment, etc. There is little or no need for a filtering device between the carburetor .10 and the auxiliary 12 since the over flow tubes 22 are well above the lower portion of the carburetor bowl 10 and hence are not likely to entrain sediment. Turning to FIG. 2 which shows the auxiliary tank 12 in detail, it can be seen to include a block (or upper chamber) assembly 40 cooperating with a glass bowl 41 and a bale 42. The block assembly 40 acts as the storage part of the auxiliary tank 12 and has cooperating therewith the float '31 affixed to the double check valve 32. The two-way control valve 32 comprises an upper 'valve 44 cooperating with the throat area 35 and a lower adjustable valve 45 cooperating with the throat area 34. The control valve assembly 32 is guided in vertical aperture 46 formed in the lower portion of the upper chamber assembly 40 and, within the limits of the distance between the upper valve 44 and lower valve 45, the throat assembly 31 is free to move in a vertical direction. The lower valve 45 is threadedly supported on the lower end 47 of the valve assembly 32 so that the relative distance between the valves 44 and 45 may be adjusted. In the exemplary embodiment, for example, when the valve 44 just contacts its throat 35, the lower valve 45 is adjusted Coutrariwise, when the valve 45 just seats against throat 34, the throat 35 is open for the passage of gasoline therethrough. The

fuel line 19 is connected into the upper chamber 43 as well as through the lower check valve 45 to the chamber 48 formed by the glass bowl 41. Whenever the level of gasoline is very low in the upper chamber 43, the float assembly 31 causes the valve 44 to rest against throat 35 which closes off the flow of gasoline from the upper chamber 43 into the fuel pump line 19. Whenever the gasoline flowing from the carburetor 10 through the overflow tubes 22 causes the float 31 to rise higher in its chamber 43, valve 44 opens the orifice between the chamber 43 and the fuel pump line 19 and closes the passage from the lower chamber 48 through the line 19 to the fuel pump 14. As noted before, the relative distance between the valves 44 and 45 may be adjusted through 45 to regulate the flow to fuel pump line 19 from the upper chamber 43 and/or the lower chamber 48 Overflow of gasoline from the carburetor traverses tubes 22 and the check valve assembly 30 into the upper chamber 43 and, whenever the valve 44 is open, it is pumped by the fuel pump 14 through the line 19 back into the carburetor '10. The air vent 36 at the top of the upper chamber 43 includes the check valve 37 to prevent an air lock in the enclosed space. Check valves '30 and 37 are identical and include depending circular shoulders 50 cooperating with retainer rings 51 and light plastic balls 52. The retaining members 51 act to retain the plastic balls 52 which are normally maintained by gravity in their lower position, which position does not block the lines 22 and 36 of the overflow pipe and air vent, respectively. However, whenever the level of gasoline in the upper chamber 43 rises sufficiently high, the plastic balls 52 .float upward against the depending shoulders 50 to block gasoline from flowing out of the upper chamber 43 through the air vent line 36 and the overflow line 22. The advantages of using these one-way or check valves in the lines are to prevent any malfunction in the equipment from causing an overflow of gasoline out onto the engine or into the carburetor. The latter, of course, is the very thing the present invention is designed to obviate.

The filter 38, which is constructed of an appropriate porous material, is of a cup-type shape and fits against the undersurface 56 of the block assembly 40. It is held there by flexible spring 53 cooperating with the glass bowl 41 and the bale 42. The lower portion of the bale 42 is threaded to receive the threaded member 54 displaceable by knurled knob 55. By rotating the knob 55 the end of the threaded member 54 bears against the glass bowl 41 to lock it firmly against the lower surface 56 of the block assembly 40 and, in turn, through spring 53 force the filter 38 firmly against the undersurface 56. With this arrangement the fuel from the fuel tank 13 enters through the line 33 and flows through the filter 38 and the check valve 45 into the fuel pump line 19.

An evaluation of the previously described system and auxiliary tank construction demonstrates that it provides a carburetor fuel level control unaffected by the vicissitudes of an automobiles motions, malfunctions of related equipment, or the presence of foreign matter in the fuel. By a plurality of angularly displaced overflow lines around the carburetor bowl, check valves in the overflow and air vent lines and a fuel filter, a system is provided which not only prevents flooding of conventional float-operated carburetors but does so in a simple, straightforward and eflicient manner. While the present invention has been described with particularity with respect to one preferred embodiment, it is obvious that numerous other arrangements may be visualized by those skilled in the art without departing from the spirit and scope of the present invention. Therefore it is to be understood that the present invention should be in no way limited except to the extent of the appended claims.

What is claimed is:

1. Fuel-level control apparatus for a carburetor having a bowl supplied through a float valve with liquid fuel from a storage tank via a fuel pump, said apparatus comprising a plurality of overflow tubes connected to the carburetor bowl adjacent to the normal fuel level therein established by its float valve, there being at least one such tube connected to a forward portion and another connected to an after portion of the bowl, an overflow tank mounted below the bowl, said tubes connecting into an upper portion of said overflow tank, means providing a vent fi'om the upper portion of said overflow tank to the atmosphere, check valves connected with said tubes and vent to prevent passage of fuel out of said overflow tank via these media, a two-way valve connecting the fuel pump to the storage tank and a lower portion of said overflow tank selectively, a float within said overflow tank, and means operatively connecting said float to said two-way valve for causing the pump to draw fuel from the storage tank when the level of fuel in the overflow tank is low and from the overflow tank when the level of fuel therein is high.

2. Apparatus as in claim 1, the two-way valve being formed integrally with the lower portion of the overflow tank, additionally comprising a cup-shaped, porous ceramic filter attached to the bottom of said overflow tank, said two-way valve having an upwardly facing inlet opening into said overflow tank and a downwardly facing inlet opening into said cup-shaped filter, a bowl-shaped enclosure attached to the bottom of said overflow tank, said enclosure surrounding said cup-shaped filter and enclosing a space around the outside of said filter, and means connecting said space to the storage tank.

3. A fuel-level controller for interconnecting carburetor overflow apertures and a fuel pump inlet and a fuel supply tank outlet, said controller comprising a substantially closed, cylindrical tank having top and bottom ends, said top end having first and second fluid passages therethrough, means for connecting the carburetor overflow apertures to said first passage, whereby overflow fuel is discharged into said cylindrical tank, said second passage opening to the atmosphere and providing an air vent, first and second ball-type check valves mounted on the under side of said top end and arranged to check the external flow of fuel from the tank through said first and second passages, whereby potentially dangerous spilling of fuel is prevented, said bottom end having a vertical fluid passage therethrough shaped to define an upper valve seat facing upwardly into the tank and a lower valve seat facing downwardly out of the tank, said bottom end being also provided with a lateral passage communicating at one end with the vertical passage between said two seats, means for connecting the other end of said lateral passage to the fuel pump inlet, a pair of valve disks connected by a stem extending through said vertical passage, said disks cooperating with said upper and lower valve seats to form a two-way poppet valve, a float inside said cylindrical tank, said stem extending above the upper valve disk and connecting directly to said float, whereby the pump draws fuel through the lower end of said vertical passage when the fuel level in the cylindrical tank is low and withdraws fuel from the cylindrical tank when the level therein is high, a cup-shaped, porous ceramic filter removably attached to the under side of said bottom end, the lower valve seat facing into the top end of said cup-shaped filter, a bowl-shaped enclosure removably attached to the under side of said bottom end, said enclosure surrounding said cup-shaped filter and enclosing a space around the outside of said filter, said bottom end being provided with still another fluid passage opening into said space, and means for connecting the last-mentioned passage to the supply tank outlet, whereby fuel from the supply tank is filtered before it is supplied to the two-way valve and malfunctioning of the valves due to dirt is prevented.

References Cited in the file of this patent UNITED STATES PATENTS 1,405,147 Mueller Jan. 31, 1922 1,781,964 Thomas et al Nov. 18, 1930 1,909,390 Ball et a1. May 16, 1933 2,695,029 Bruegger Nov. 23, 1954 2,774,365 Stewart et a1. Dec. 18, 1956 2,808,102 Lidecker Oct. 1, 1957 FOREIGN PATENTS 125,023 Great Britain Apr. 10, 1919

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