US1819698A - Carburetor - Google Patents

Description

Aug. 18, 1931. E. BOW ET AL CARBURETOR Filed July 12. 1928 3 Sheets-Sheet 2 8 .v 6 (YMMV- .in. H g 4 m l 3 n s H 1 M I a2 a w w Q .i 4 M: O 4 m INVENTORS.

BOW and LOU/6 w. JEN/f6 THE/f? ATTORNEY.

Aug. 18, 1931.

CARBURETOR Filed July 12. 1928 3 Sheets-Sheet 5 Zbuenj 0ns.

EDMUND 50 w n/vo Lou/s W. Jmrs mam Mn Patented 1 mg. is, ten

PATENT OFFICE.

EDIEIUNID BOW LOUIS W. JENKS, 'GE ZBERKELEY, CALIFORNIA cnanonnron Application filed July 12, 1928. Serial No; 292,095.

Our invention applies particularly to devlces for mixing fuel and air such as are 're uired for internal combustlon engines.

t is an object of our invention to provide a carburetor with improved means for proportioning the fuel mixture to accommodate varying engine speeds and loads, and 1t 1s a further object of our invention to provide a carburetor which automatically ad usts itself, or compensates, for these varymg conditions. a

It is another object of our invention to pro-- vide a carburetor for automatically-supplying a lean mixture for high efliciency at light,

1 engine loads and a rich mixture for high power at heavy engine loads.

It is a further and important object of our. invention to provide a carburetor of 1nher-.

ently simplecharacter without undue comg plications, which yet possesses the desirable metering characteristics above suggested and set forth-more in detail herebelow.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the follow ing description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the speci-- fication. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claims. Referring to the drawings: Figure 1 is a from elevation of a carburetor embodying our invention.

Figure 2 is a view similar to Figure 1 but with the movable venturi and its motivating 4o vacuum cylinder in axial section.

F'gure 3 is a right end elevationof-the carburetor with the vacuum cylinder in axial section and with the actuating piston shown in its uppermost position. Figure 4 is an end elevation of the vacuum through the conduit.

pilot valve with its lower portion broken away to disclose the axial section thereof.

' Figure 5 is a median longitudinal section of the connecting nipple for the pilot valve.

Figui'e 6 is an elevation of the mutilated a0;

vacuum-relief screw removed from the'co necting nipple of Figure 5.

Figure 7 is a front elevation of the carburetor attached to a gas engine.

Figure 8 is a diagrammatic view showing all the conduits of the carburetor of this invention.

A gasoline engine 6 (Fig. 7) has an induc tion conduit 7 here shown in the form of a manifold, through which air, oran ex losive 60 mixture of air and fuel, is arrange to be drawn into the engine. A mixin device or carburetor is provided for supplying fuel in proper proportions to the air-stream flowing A carburetor housing 11 (Figs. 1 and 2) forms an" air inlet conduit or passage 12 which is adapted to be connected to the induction conduit 7 by a bolting flange 13 of the housing. The conduit 12 then forms a continuation of the-conduit 7. A butterfly-or other suitable throttle valve 14 is pivoted in the conduit 12 near its upper portion to control the flow of air therethrough and into the engine 6, a control lever 16 being provided for moving the throttle valve. In Figures 1 and 2, the throttle valve is shown nearly closed as for the idling operation of the engine.- The passage 12 is constricted at a position below the throttle valve,-by a venturi 18 (Fig. 30 2) having its constricted throat at the 051- tion marked by a heavy dash line 19 in igure 2. The venturi as here shown is anannular member having its outside wall closely fitting the inside wall of the conduit 12 and having its inside wall tapering from both ends to the constricted throat 19 in the usual manner. The purpose of the venturi is to effect a lowering of pressure throughout its extent in the conduit, and producing a minimum pressure or ma-ximum suction at or very sli' ht-ly below the throat 19.

asoline or other suitable fuel is fed into i the venturi through a nozzle 21 having an emission orifice at its tip 22. Conventional means are employed for supplying fuel to the nozzle 21; the nozzle being connected to an atmospheric fuel reservoir 23 of the carbu retor, and the fuel therein being maintained at a level slightly lower than that of the orifice tip 22 by a float mechanism or other suitable means (not shown). As air is drawn 7 through the conduit 12 it causes a reduction of pressure in the venturi which sucks fuel out of the nozzle 21; or in other words prodemand is small, the mixture would be lean.

While itmay be desirable to vary the richness of the mixture to produce maximumpower on the one hand or maximum efliciency on the other hand, the aforedescribed mechanism is not ideal for the purpose because large air-"demand may be due either to high engine speed at moderate throttle opening or to wide-open throttle at moderate engine s eed. These two conditions dictate widely ifierent mixture proportions, but the carburett-ingmech'anism so far described cannot properly discriminate between the two conditions.- It is therefore desirable to modify the fuel-feeding characteristics of the venturi Y and fuel emission nozzle aforedescribed.

Means are therefore provided for varying the relation between the venturi and'the fuel nozzle. As here shown, the venturi 18, instead of being fixed to the conduit 12, is slidable therein and may be moved axially of itself up to the position shown by dotted lines in Figure 2. The orifice tip 22, 'on the other hand, remains fixed, so that as the venturi Y lubricating film of fuel between the slidable is moved up, the distance between its throat and the nozzle is increased, so that the sucreduced.

Small lubrication holes 25 are drilled through the venturi so as to maintain a thin tion efiect-upon the orifice is correspondingly venturi and the conduit in which it moves.

The venturi is urged downward to its position of greatest effectiveness with respect to the fuel nozzle, by an adjustable spring 24 and pull-rod 26.

Means are provided for movingthe venturi against the action of spring 24. Screw pegs 27 are tapped radially into the venturi wall, and extend out through vertical slots in the conduit 12 of the carburetor. 7 Movement of the venturi wall is arranged to be adjustably limited by means of a screw 30 disposed in a nected nearits base by a nipple 37' (Figs. 3 t

and 5), a suction line 38 (Fig. 7), and other means subsequently to be described in detail, to the induction conduit 7-12.

In operation, as suction in the conduit 7-12 increases, the piston 32 of the'vacuum cylinder in communication therewith is drawn down, lifting the venturi against the counteracting spring 24, and thus reducing the effectiveness of the venturi with respect to the fuel nozzle 21. Thus the mechanism aforedescribed constitutes compensating means for restricting the proportion of fuel feed from the fuel emission orifice 22.

The proportion of fuel to air for maximum efiiciency at relatively light engine loads would not produce maximum power when the engine was heavily loaded; or, as it is more commonly expressed, a richer mixture is required for maximum engine power, and a leaner mixture for maximum engine efiiciency. It is therefore desirable to permit a richer mixture as the opening of the throttle 14 increases. The suction line 38 leading to the actuating vacuum cylinder 34 is therefore preferably connected to the conduit 7-12 at the engine or induction side of the throttle 14 as distinguished from the carburetor inlet or atmospheric side of the throttle. Of course there is no truly atmospheric? side of the throttle, because the entireconduit 712 is normally slightly below atmospheric pressure, but it will be apparent that when the engine is running at fairly high speed with the throttle nearly closed, the suction on the engine side of the throttle will be more intense than that on what is termed the atmospheric side of the throttle; and this effect becomes less marked as the throttle opening increases. Thus it will be understood that by connecting the suction line 38 of the actuating vacuum cylinder to conduit 7'12 on the engine side of the throttle, its compensating action on the venturi and. fuel orifice will be greater at a given engine speed as the engine load decreases. In other words the ratio of gasolene to air will be reduced more, causing a leaner mixture, at light loading of the engine than at heavy loading.

A mixture lean enough for maximum efficiency at ordinary light loads would be unsatisfacto at idling speed with an engine not un er load. Means are therefore provided for incapacitating the mixture compensator when the throttle is nearly closed. The suction line 38 from the conduit 7--12, instead of leading directly to the nipple 37 forming the inlet to vacuum cylinder 34, has a ilot valve interposed therein. The pilot va ve consistsof-a housing 39 (Fig. 4) having an upper chamber 41 communicating through coupling fittings 41 with the suction line 38, a lower chamber 42communicatin through the nipple 37 with the vacuum cy inder .34, a valve seat 43 between the two chambers, and a valve stem 44 having its lower end beveled to form a valve face 46 for coaction with the seat 43. The upper end of the valve stem projects out through a stuffing box 47, and the pilot valve is supported by its piping connections at an appropriate inclination to position the upper end of the valve stem in the path of a bellcrank extension 48 of the throttle-control lever 16. An adjusting screw 49 in the ex-.

tension 48 is adapted to abut against the top of the valve stem 44 and to hold the pilot valve 43-46 closed when the throttle is closed to idling position of the motor. When the throttle is opened, the extension 48 movesupward from the'pilot valve, and a light spiral compression spring 51 on the valve-stem then lifts the pilot valve oif its seat permitting normal compensating action of the vacuum cylinder and movable venturi.

Vacuum relief means are provided for breaking the residual suction in the vacuum cylinder when the ilot valve is closed. A T extension 52 oft e connectingnipple 37 (Fi 5) at the base of the vacuum'cylinder,

- is t readed to receive a mutilated screw 53 filed to atapering flatness on one side. The.

flattened mutilation of the screw permits slight air leakage into the vacuum line. When the valve 44 is open, continued s'uction in the conduit 7-12 renders this light leakage of air ineffective to break the vacuum, but when thevalve 44 is closed the residual suction 'in the vacuum cylinder is readily dissipated by this silght leakage. The amount of leakage may be adjusted by turnin the screw further into the extension decrease leakage; by unscrewing the screw, more leakage is obtained because of the taper of the flattened side of the screw.

Means are provided for incapacitatin the mixture compensator when the trott e is opened more than a moderate amount, corresponding to a heavy engine load. The

- lower end of the valve stem 44 is tagiped to receive a screw 54, the head 56 0 which forms a second valve face opposite to the face 46. A valveseat 57 is formed in the housing 39 to coact with the valve face 56 when the stem 44 is lifted above a certain distance determined by the length of thescrew 54. A

I to determine the throttle opening at which.

plug 58 in the bottom of the housing 39 per mits removal of the screw 54 where it is desired to dispense with this feature, or permits its replacement by a longer or shorter screw the compensator is to be incapacitated. The screwis preferably proportioned to incapacitate the compensator at about one fifth throttle opening, corresponding in the average automobile engine to a steady speed of about thirty miles'per hour on a level road. If a quick and powerful acceleration is desired,

.it is only necessary to press the throttle slightly beyond this economy range of openin to incapacitate the compensator. o

t will be noted that in the present embodiment of the invention the valve 5657 incapacitates the mixture compensator so that the compensator is ineffective whenever the throttle opening exceeds a certain amount; or expressed more directly, the mixture compensator is only effective when the throttle is at least partially closed. However,

this arrangement may be chan ed if desired to 'make the compensator e ectivc at all times.

A stop-cock 59 in the suction line 38 is pro-. vided to shut ofl the vacuum to prevent displacement of the tube during fuel nozzle ad- Justments.

It will be apparent that the vacuum cylinder and actuating piston 32 could be placed in other positions, such as directly beneath the venturi; being connected thereto directlby the rod 26 instead of the rocker arm 28.

he illustrated embodiment is however referable in certain instances because. 0 its greater compactness.

We claim 1. A carburetor comprising a conduit; a venturi in said conduit; a fuel nozzle in Y said venturi a throttle valve in said conduit at the induction side of said venturi; dompensating means for moving said venturi relative to said nozzle, comprising a vacuum w cylinder, a piston in said cylinder, means operatively connecting said venturi to said piston for operative movement therewith, pi ing connecting said vacuum cylinder to said' conduit at the induction side of the throttle therein; a pilot valve interposed in said piping, means for closing said pilot valve tojincapacitate said compensating means, and means for relieving suction in said vacuum cylinder when the pilot valve is closed. v

2. A carburetor comprising a conduit, a venturi in said conduit, a fuel nozzle in said venturi, a'throttle valve in said conduit at the inductive side 'of said venturi, compensating means "for, moving said venturi relative to said nozzle, comprising a vacuum cylinder, a piston in said cylinder, means operatively connecting said veturi to said piston for operative movement therewith, piping connecting said vacuum cylinut der to be-adult the induction side of the throttle therein, a pilot valve interposed in said piping, means operated by the throttle for closing said pilot Valve to incapacitate said compensating means, and means for relieving suction in said vacuum cylinder when the pilot valve is closed.

In testimony whereof, we have hereunto set our hands at Oakland, California, this 10 5th day of July, 1928.

EDMUND BOW. LOUIS W. JENKS.

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