US2261490A - Carburetor - Google Patents

Description

w. H. WEBER CARBURETOR Nov. 4,1941.

Fil ed May 22, 1939 ATTORNEY Patented Nov. 4, 1941 OABBURETOR' Walter H. Weber, Detroit, Mich assignor to Detroit Lubrlcator Company, Detroit, Mich a corporation of Michigan Application May 22, 1939, Serial No. 274,882

5 Claims.

My invention relates to new and useful im- 7 movements in carburetors and more particularly toe. carburetor for supplying fuel mixture for an internal combustion engine.

An object of my invention is to provide a carburetor which is operable to lift fuel from a low lever supply tank, thereby eliminating the neces-,

sity for the usual vacuum tank or fuel feeding pump.

Another object is to provide, a carburetor in which the fuel and air supplied to the engine will be uniformly mixed.

Another object is to provide means to supplemental fuel for acceleration.

Another object is to provide means for increasing the ratio of fuel to air for engine starting and for cold engine operation.

The invention consists in the improved construction and combination of parts, to be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawing, to be taken as a part of this specification, I have fully and clearly illustrated a preferred embodiment of my invention, in which drawing- 7 Figure 1 is a view in vertical central section of a carburetor showing my invention, and

Fig. 2 is a top plan view of the carburetor of Fig. 1 but having the air inlet valve broken away to show the internal construction.

Referring to the drawing by characters of reference, i designates generally the carburetor casing having a vertical passageway theresupply through with an open upper end portion 2 providing an air inlet 'chambert. Opening downward from the chamber 8 eccentrically thereof,

there is a mixing chamber a which discharges through a throttle body member 5 having a flange t by which the carburetor may be secured to the inlet manifold of the engine. Within the throttle body member 5 there is a butterfly type throttle valve '7 rotatably supported by a throttle shaft 8. Positioned at one side of the mixingchamber a there is a vertically extending cylindrical dash-pot and pump chamber a which iseccentric of but directly beneath the air inlet 3. The chamber 9 is separated from the air inlet 3 by a horizontally extending wall it which has therein a cylindrical recess ll opening downward into and concentrically with the chamber 9. A guideway it extends concentrically from the upper end of the recess il through the wall it to the air inlet 3. Reciprocally guided and fitting in the guideway ii there is a valve stem I3 which ex- 55' tends at its upper end into the inlet 3 and has pivotally secured thereto a link 14. Within the air inlets and controlling admission of air to the I mixing chamber 4, there is e. suction responsive air valve plate I5 which is eccentrically mounted on a shaft It to swing downward across the entrance to the mixing chamber 4. The link M is pivotally secured toa. bracket l1 secured to the underside of the plate It on the opposite side of shaft lBfrom the chamber 5 so that the valve stem. It will be lifted on opening movement of the air valve. A supporting member i8 projects from the wall' I0 into the mixing chamber A and has a vertical bore i9 therethrough concentric with the longitudinal axis of the mixing chamber. Tightly fitting and secured within the bore is there is a nozzle member 26 which extends downward therefrcm- The nozzle member 26 has a converging-diverging Venturi-like bore providing a throat 2i positioned within the length of bore is. The throat preferably comprises a short downward flaring portion of greater included angle than the diverging discharge portion 22 of the nozzle member so that the throat entrance from the converging air inlet portion 23 of the bore will be the most restricted portion of the nozzle bore. Supported by the casing i there is a float chamber member it having a constant level reservoir 25 with a fuel inlet 26 from the usual supply tank. The inlet 25 is controlled by the usual float operated valve mechanism 27 which serves to maintain the liquid levelsubstantially constant at say the line L-L. The reservoir 25 is provided with a calibrated air inlet to from atmosphere, the reservoir being otherwise sealed against air admission. A fuel supply conduit 29 leads from the bottom of the float chamber into the lower end of the dash pot chamber 9. Reciprocal in the wall recess ii there is a tubularvalve port member so having at its upper end a restricted por- 1 tion at providing a valve port. The, lower end portion 32 of member 30 is of enlarged internal diameter and extends downward into the chamber 9.. The upper portion of member 30 is provided with an external rack cooperable with a pinion 33 for reciprocating the member 80. Reciprocally fitting within the tubular portion 82, there is a sleeve member 33 having a flange 8d at its lower end on which seats an annular cupshaped piston 35. The tubular valve port member 30 is urged upward and the piston 35 is opposed in upward movement by a helical coil spring 38 which surrounds the sleeve member 83 and the lower tubular portion 32 and which abuts a spring seat member "secured to and extending laterally from the portion 32. Intermediate the ends of the valve stem is there is a metering valve 38 cooperable with and extending through the port It. The lower end portion of the stem I I is secured as by a cross pin is in a spider 4| rigidly fixed within the sleeve member 83 Leading from the recess ii at its upper end and on the outlet side of port ll there is a fuel conduit 4| which opens into the bore I! for communication with a calibrated orifice 42 which opens into the throat 2i. A vapor conveying conduit 48 for gas and air extends through the wall I. from the reservoir 25 above the liquid level therein.

The conduit 43 has a calibrated opening 44 into the reservoir 26 which is proportioned relative to the calibration of the atmospheric bleed 28 so as to control the sub-atmospheric pressure or depression over the liquid in the reservoir.- The other end of-conduit 43 opens into the bore I! above the conduit 4| and communicates with a calibrated orifice 45 which opens into the throat 2i directly above and on the air inlet side of the orifice 42 so that any discharge from the orifice 45 will pass directly overuan'd across the outlet of orifice 42. The conduit 43 communicates through a supplemental fuel conduit 48 with the dash-pot chamber 9 but out of direct communication with the main fuel conduit through the sleeve 33 and portion 32; that is, the conduit 48 opens into the annular pump chamber above the piston 35 and surrounding the lower end portion of the valve port member 80. The conduit 48 is provided with a downward seating ball check valve 41 having sufiflcient weight to hold the conduit 46 closed against discharge of fuel by suction in the conduit 43.

The operation of this carburetor is as follows: When starting a cold engine the pinion 33 will be rotated to move the port member 3 downward against the force of spring 36, thereby increasing the opening of the port 3i. This ad- Justment will increase the resistance to opening movement of air valve. it by increasing the compression on the spring 86, thereby reducing the air supplied for a given sub-atmospheric pressure in the mixing chamber t and will also in crease the effective fiow area of the fuel supply conduit through orifice M to further increase the ratio of fuel to air for all positions of the air valve l 6. When the engine has fired and is running under its own power, the pinion tit will be rotated to return the valve port member 30 toward normal operating position and completely to normal position when the engine is thoroughly warmed up. The sub-atmospheric pressure in the mixing chamber 6 will not only act on orifice 42 to draw fuel from the reservoir ill but will also act through conduit 3 to reduce the pressure over the liquid in the reservoir so that fuel will be lifted from the supply tank and drawn into the reservoir when the float mechanism opens the inlet passageway 26. The air and gas drawn into the throat it through orifice 45 will discharge directly over the fuel orifice 42, thereby aiding the feeding of fuel into the nozzle member by aspirating action. This air and gas will also be discharging directly into the fuel from orifice 42 due to the throat flare and the main air stream passing the throat so that the liquid fuel will be broken up and intimately mixed with the air in the nozzle member, The air bleed 28 provides a differential of pressure above and below the fuel so that fuel will feed through the port or orifice 42. During idling operation of the engine the air valve ll will remain in substantially closed position so that the nozzle member 20 will have very little boosting effect by Venturi action. As the throttle 'l is opened, increasing the sub-atmospheric pressure in the mixing chamber 4 and on the outlet side of air valve II, the valve II will move toward open position in accordance with the sub-atmospheric pressure and the resistance afforded by the spring 38 and will lift the fuel metering valve relative to port II to increase the fuel supplied relative to the increased supply of air. As the air valve moves toward open position, increasing the rate of air flow through the carburetor, the nozzle member will become effective to boost the suction over the liquid in the reservoir on the fuel orifice 42. If the throttle valve 1 is moved quickly toward open position for engine acceleration, the fuel in the annular pump chamber will be compressed by the piston II and be discharged through conduit 4| into the vapor conveying conduit 43 and thence be discharged through orifice 45 into the bore of nozzle member 20, thus providing the necessary enriched mixture for quick acceleration.

By positioning the nozzle member 2| on the outlet side of air valve l 5 such that the air valve controls the air supply to the nozzle member inlet 23, the disadvantage of frost forming in the throat of the nozzle member is eliminated. The forn: tion of frost in the throat of a nozzle member \hich passes or upplies substantially all of the air for low speed or engine idling operation will obstruct the fuel orifice and seriously impair carburetor operation. The high air velocity through the nozzle member at low e'ngine speeds is avoided by my construction wherein only a portion of the airat low speeds passes through the nozzle member, the, remaining air passing around the nozzle member and mixing zvth the fuel discharging from the nozzle mem- It will be apparent that this carburetor can also be used as a gravity feed carburetor or one having the float chamber fed by means of a vac uum tank or fuel pump. If it is desired to'so utilize the carburetor, it is only necessary to increase the size of bleed 23 so that substantially atmospheric air will exist over the fuel in th reservoir 25.

What I claim and desire to secure by Letters Patent of the United States is:

l. A carburetor comprising, a casing having a passageway therethrough with an air inlet and a fuel mixture outlet, a nozzle member having a converging-diverging bore providing a throat, said bore having one end open for air admission and having its other end discharging into said passageway, a fuel reservoir, a fuel supply conduit leading from said reservoir and discharging into said bore at said throat, a vapor conveying conduit leading from said reservoir above the liquid level therein and discharging into said bore at said throat, the point of discharge of said fuel conduit being substantially at,the point of low pressure in the discharge path of vapor from said vapor conduit, the opening of said vapor conduit into said bore being on the air admission side of and closely adjacent the open ing of said fuel conduit into said bore so that the vapor is discharged acrossv the fuel conduit opening to increase the suction effect on said fuel opening and to thoroughly blend the vapor and fuel in said bore, a supplemental fuel supply conduit leading from said fuel conduit into said vapor conduit, and meansto control the discharge'of fuel through said supplemental conduit,

to said bore.

2. A carburetor comprising, a casing having a passageway therethrough with an air inlet and a fuel mixture outlet, a nozzle member having a converging-diverging bore providing ,a throat, said bore having one end open for air admission and having its, other end discharginginto said passageway, a fuel reservoir, a fuel supply conduit leading from said reservoir and discharging into said bore at said throat, a vapor conveying conduit leading from said reservoir above the liquid level therein and discharging into said bore at said throat, the point of'discharge of said fuel conduit beingsubstantially at the point of low pressure in the discharge path of vapor from said vapor conduit, the opening of said vapor side of and closely adjacent the opening of said fuel conduit into said bore so that the vapor is discharged across the fuel conduit opening to increase the suction effect on said fuel opening and to thoroughly blend the vapor and fuel in said bore, a supplemental fuel supply conduit leading from said fuel conduit into said vapor conduit, a pump operable to discharge fuel through said supplemental conduit to said bore, and an automatic valve in and closing said supplemental conduit against feeding of fuel by pressure reduction in said vapor conduit.

3; A down-draft fuel-lifting carburetor com prising, a casing having an open-ended passageway therethrough with an air inlet at its upper end and a fuel mixture outlet at its lower end, "an eccentrically mounted valve plate in said air inlet and responsive to suction in-said passageway, said valve plate being cooperable with said air inlet upon movement to admit air to said passageway along its peripheral surface, a downfrom the side walls of said'passageway on the outlet side of said valve plate, said nozzle memher having an open-ended converging-diverging bore providing a throat, a fuel reservoir, a vapor conveying conduit leading from said reservoir above the liquid level therein and opening lat- 'erally into said throat, a fuel conveying conduit leading from saidreservoir below the liquid level therein and opening laterally into said throat closely adjacent to and below the opening of said vapor conduit, a pump chamber in said fuel conduit. a tubular valve port member reciprocally fitting in said fuel conduit'and having a portion extending into said pump chamber, a sleeve member in saidipump chamber and reciprocally fitting said extending portion, a piston carried by said sleeve member and fitting said chamber.

a fuel metering rod extending through said port member and interconnecting said valve plate and said sleeve member, a helical coil spring sur-' rounding said sleeve member and interposed between said tubular member and said piston to oppose movement of said piston and said valve plate, and means to adjust said port member to regulate the eifective flow area of said fuel conduit.

4. A down-draft carburetor comprising, a casing having a tubular air inlet portion at its upper end, a mixing chamber passageway and a dash-pot chamber having substantially parallel longitudinal axes, said mixing chamber passageway opening downward from and eccentric of said inlet portion, said dash-pot chamber being positioned'besides said mixing chamber passageway and directly below said inlet portion, a laterally extending wall in said casing separating said dash-pot chamber from said inletportion and havingan elongated recess opening into said dash-pot chamber, said wall having a guideway extending concentrically fromsaid recess and opening into said inlet portion, the longitudinal axes of said recess and said guideway being substantiallyparallel to the axes of said 'mixing chamber passageway and said dash-potchamber, a valve stem extending through said guideway into said dash-pot chamber and said inlet portion and having a metering valve intermediate its ends, an eccentrically mounted valve plate in said inlet portion and connected to said stem,"

an open-ended downwardly discharging nozzle member extending longitudinally of and spaced fromthe walls of said passageway and supported by said wall,.thelongitudinal axis of said nozzle -i said dash-pot chamber and connected .to said valve stem, a valve port member in said recess. and surrounding said metering valve, and means to supply fuel to said dash-pot chamber.

5. A carburetor comprising, a casing-having a passageway therethrough with an air inlet and a fuel mixture outlet, a nozzle member having 'a converging-divergingbore providing a throat,

' charging into said bore at said throat, means to supply a .gas to said reservoir, a gas and vapor conveying-conduit leading from said reservoir above the liquid level therein and discharging into said bore at said throat, the longitudinal axis of said vapor conduit being at an angle relative to the longitudinal axis of said fuel conduit, said axes intersecting within said bore closely adjacent the opening of said fuel conduit into said bore, the opening'of said vapor conduit into said bore being on the air admission side ofand closely adjacent the opening of said 7 "fuel in said bore.

WALTER H. WEBER;

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