US1532229A - Carburetor - Google Patents

Description

April 7, 1925. 1,532,229

M. G. CHANDLER.

cumrsumsroa Filed 'Oct. 14 1922 Illllllllh ldatented Apr 2, 1925.

ha/r nd Emil o G. CHANDLER, OF CHICAGO, ILLINOIS, ASSXGNOR, BY MESNE ASSIGNMENT$, T CURTIS B. CAMP, TRUSTEE, Q1 OAR L' ABK, ILLINOIS.

CABBURETOR.

Application filed October 14, 1922. Serial 210. 594,522.

To aZZ whom it may concern."

Be it known that I, MILFORD G. CHAND- LER, a citizen of the United States, and resident of Chicago, in the county ofCook and State of lllinois, have invented a certain new and useful Improvement in Carburetors, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this spedification.

This invention relates to carburetors for internal combustion engine's,-and more particularly to that class of carburetors provided with means for raising fuel from a low level tank to the carburetor by suction derived from the engine, but augmented for fuel lifting purposes. The advantages gained by augmenting the mixing chamber suction for fuel lifting purposes are fully set forth in my Patent No. 1,370,947,;dated March 8, 1921, and need not be stated here. In carburetors of the suction lift type, it

is important that the restriction to the air flowing into the carburetor be maintained as slight as will properly produce the atomization of the fuel and the necessary suction for lifting the fuel from the low level supply tank to the carburetor. It is the attainment of these results, together with the sim plification of structure, that constitute the principal objects of my invention.

A further object of the invention is the provision of means in the form of a manually controlled air duct' for opposing the opening of the main air valve, thus provid: ing a rich mixture for starting purposes.

A further objectof the invention is the provision of means for restrictedly admitting atmosphere to the hollow portion of the main air valve whereby it assumes a more nearly closedposition than normally for providing a much increased suction'for emergency purposes. Provision is also made for controlling the fiow of fuelto the nozzle under these conditions toprovide a proper mixture. The accomplishment of these ob-' jects will be more fully explained as the description of the apparatus progresses.

My invention is illustrated in the accompanying drawings, in Which-- Figure 1 is a vertical section;

Figure 2 is a combined section and elevation taken on the lines 2 -2 of Figure 1;

Figure 3 is a section taken on the line 33 of Figure 1; and 4 Figure 4 is a modified form of valve mechanism arranged forthe accomplishmentof an additional function. The main body 5 of cast metal provides a tubular induction passage. 6 and an integral cover 7 for the fuel chamber 8, and also includes a flange 9 for attachment to the flange on the intake manifold of the internal combustion engine to which the mixture of fuel and air'is to be supplied; A throttle 10 is provided in theusual position within thev induction passage, and is wise direction, as indicated by the arrow. When the throttle is in closed, orsubstantially closed, position, the main supply of fuel for o erating the engine is obtained through the idling jet 11 which communicates at this time with the high suction side of the throttle. This idling jet 11 communicates with a chamber 12, which inturn comemunicates with the induction passage 6 through a port 14 and with the fuel. in the float chamber 8 through an opening 15' and the duct 16, the opening 15 being controlled by the needle valve 17.

A conical member 20 constitutes the entrance to the induction passage 6v and is normally closed by a reciprocable valve member 21. A portion of the external wall of the valve member 21 lies substantially parallel with the inner wall of the conical member 20, so that as the valve opens. the space formed between the valve and the conical member 20 enlarges, the inner' and outer walls remaining parallel. The space which is thus formed enlarges in cross'sectional adapted to be opened by rotation in a clockarea toward the.interior of the carburetor 'and, therefore, simulates a Venturi tube. in

creating a high suction at a region just posterior to the area of greater restriction as'air is drawn through it. Valve memberQl is provided with an enlargement at 22-which localizes the restriction and which seats upon the inner surface of the conical member 20 when the valve is fully closed. The valve member 21 is of hollow construction and is provided with a plurality of radial fuel delivery ports 24 which terminate at the surface of the valve at positions just posterior to the enlargement 22, this position being substantially that of the greatest suction or pressure reduction for all positions of the valve member 21. loosely fitted within the valve member 21 and is pressed downwardly against an inner circumferential surface 26 by a spring 27 forming a substantially sealed joint. The said spring is of proper strength to maintain within the induction passage 6 a suitable suction or depression, which increases with engine demands.

Extending across the interior of the body 5 is a bridge 30 which carries an annular )iston member 31. This piston has a ree working fit within the inner cylindrical surface of the valve 21. The sleeve is also provided with a free working fit within the lnner cylindrical bore 32 of the piston 31.

A nozzle Vent-uri tube 34 is fitted diagonally into a portion of the bridge and is arranged to discharge into the bore 32 of the piston 31 andthrough the sleeve 25 to the a radial ducts 24 in the valve member 21, the

entranceend of this Venturi tube 34 being open to atmosphere. The Venturi tube 34 is threaded into the housing 5, the opening being somewhat enlarged at 35 to provide an annular fuel passage, thispassage being in communication with the duct 16 for 0b taining fuel from the lower part of the float chamber. The nozzle Venturi tube is pro- Vided with a plurality of small discharge orifices 36 from which fuel is delivered into the incoming stream of air.

The throat of the Venturi tube 34 is of small diameter so as to provide a restriction which, even atthe lowest idling engine speed, causes a suction to be maintained Within the induction ass-age 6 suflicient for atomization of the uel and for creating suction for lifting fuel to the float chamber 8, as will behereinafter described. The throat of this Venturi tube is provided with a slight step or abrupt enlargement at 37, the purpose of which is to increase the area to compensate for the increase in pressure which would otherwise be caused by the fuel and fuel vapor admitted through the jet openings 36 when the enlargement is not provided.

A small vacuum Venturi tube 40 is preferably pressed, into a bore in the housing 5, the inner end of this, tube terminating in the region of the external surface of the valve 21, this surface-being suitably contoured to control the flow of air througlrthe vacuum Venturi tube 40 for different positions of the valve 21. An annular groove 41 is provided in the external surface of the Venturi tube 40, this groove being in communication with the throat of the Venturi tube through ducts 42 and being ins communication with the upper spaces of the float chamber through a duct' 43.

A duct 44 forms a communication through A sleeve 25 is the piston 31 and portions of the body, between the inner space in the valve 21 and the external atmosphere. This duct is normally closed at the external end by a revolvable valve and cam member 45, which is held against a plane surface on the body 5 by means of a screw 46 and spring washer 47. Two portions of'the duct 44 extend through the casting at right angles to one another, the communication between them being completed through a recessed portion 49 of the Venturi tube 37. The cam is provided with a lever arm 48, preferably connected through a rod or wire (notshown) so that it may be adjusted from the drivers position. The lower edge of the, cam 45 overlies the entrance to the vacuum Vcnturi tube 40 and is so shaped that by the rotation of the cam, the entrance to the Venturi tube 40 may be obstructed to a greater orless degree. When the cam 45, as viewed in Figure 2, is rotated in a counter-clockwise direction through an angle of substantially 45 degrees, the cam entirely blocks the entrance to the vacuum Venturi tube 40. When the cam is in this position, the opening 50 therein registers with the external end of the duct 44, thus admitting atmosphere to the space within the valve 21. tending to prevent its opening under the influence of suction in the chamber 6. In Figure 4 a modification of the cam 45 is illus trated having an additional opening 51 therein and an additional cam section 52 thereon, said opening 51 permitting a small amount of air to enter the hollow part of the valve 21 so that greater mixing chamber suction will be required to lift it and the cam 52 being so shaped as to provide a correct mixture under the high suction condition. The result of these arrangements is to provide a high carburetor suction for lifting fuel under emergency conditions such as may occasionally occur in attempting to ascend a grade so steep that the normally maintained float chamber suction will not lift the fuel.

The float chamber may be of any ordinary constant level construction, and is preferably, as here shown, provided with a float 55 pivoted at 56 and controlling a valve 57, fuel being admitted to the filter chamber at the pipe connection 58. The filter chamber housing 59 maybe rotated for convenient pipe connection and is held in sealed contact with the cover 7 of the float chamber by means of a threaded nut 60 engaging the stem 61. The bowl 62 on the float chamber is held in sealed contact with the cover 7 by means of a hollow nut 63 which engages the lower end of the stud 61. The base of the float chamber 62 is pressed conically so as to form a dome arch which will sustain a high pressure without material fiexure, enabling a perfect seal to be effected between bowl and cover and between bowl and nut 63. A plug 64 is provided in the nut 63 for draining off the water and dirt which hi evitably collects in" the bottom of the float chamber.

The structure which is described operates somewhat differently under the idling condition of the engine than it-does under conditions with the throttle somewhat more widely open. Under idling conditions the. amount of air which is admitted to the intake manifold of the engine around the valve stems constitutes a much greater proportion of the total amount of air than under anyother engine operating conditions. This is true because the sire of the openings around the valve stems is constant. and the suction in the intake manifold tending to draw air in around the valve stems 1s considerably higher at idling than under other operating conditions. For this reason. it is necessary, in order that the mixture of fuel and air may be proper for idling. that a greater amount of fuel be admitted in proportion to the air passing through the carburetor than at higher speeds. It is also important that the amount of excess fuel thus admitted for idling be readily adjustable without materially disturbing the proportions of the mixture under other engine running conditions, because, as the engine wears, the space around the valve stemsbecomes greater and the amount of air admitted during idling, therefore, varies materially with the age of the engine, requiring anadjustmeni for compensation. During idling, a part of the mixed air and fuel is drawn into the intake manifold of the engine around the throttle 10, while the remaining part is drawn in through the duct 11. A suction will be maintained in the chamber 12 which is a mean between the suction on the engine side of the throttle 10 and that in the induction passage 6. The adjustment of the needle valve 17 provides the amount of fuel necessary for obtaining a correct mixture under these operating conditions. When the throttle 10 is opened to a power position, the suction at the openings 11 and 14 is less than that in the float chamber and no fuel is, under these conditions, delivered through the openings 10 and 14.

The suction created in the induction passage 6 is communicated to the interior of the valve 21 through the space lying between the sleeve 25 and the piston 32. This causes the valve 21 to rise to a position somewhat above normal, thus admitting air to the induction passage 6 around the enlarged lower end of the piston 22. The .venturi shape of the space between the conical member 20 and the piston 21 causes a material augmentation-of the suction at the ends of the ports 24 and thus creates a suction on the nozzle Venturi' tube 34 which is considerably greater than that existing in the induction passage 6. The suction created at the throat of the nozzle Venturi tube 34 and available thereat for drawing fuel out of the float chamber is still greater than that at the discharge end of the nozzle Venturi tube. so that by the multiple arrangement of Ven- ,turi tubes. a very greatly enhanced suction is obtained for drawing fuel out of the float chamber.

The suction existing in the induction passage 6 is communicated to the inner end of the vacuum Venturi tube 40 causing a flow of air therethrough which creates a suction at its throat and consequently in the upper spaces of the float chamber 8, this suction being utilized for lifting fuel to the float chamber from a low level source of supply, such as the tank at the rear of an automobile. The richness of the mixture will obviously depend upon the relative suctions within the float chamber above the fuel and at the ducts in the nozzle Venturi tube 34. Relative suctions can be. manually controlled by the adjustment of the cam 45, the less restriction on the external end of the Vonturi tube 40, the greater the quantity of air passing through it, and, consequently. the greater the suction at its throat. The greater the suction in the. float chamber, the less Will be the differential suction effective to cause the delivery of fuel into the nozzle Venturi tube, and, consequently, the leaner will be the mixture. For anv engine demand, no matter whether it is caused by high speed and light load. or by low speed and greater load, there will be a specific and definite position which will be assumed by the valve 21. Further delicate adjustment of fuel feeding differential, which is the difference in suction between that in the float chamber and that at the nozzle ducts 36 is obtained by the degree of obstruction at the inner end of the vacuum Venturi tube 40 caused by the outer surface of the valve 21, this outer surface being properly contoured to give the right degree of suction for each of itsvarious positions.

In starting a motor when cold, it is desirable to create a very high suction for assisting in atomizing the uel and i 15 also desirable that an over rich mixture be delivered. By moving the cam 45 to a position so that the opening 50-registers with the duct 44, in which position the vacuum Venturi tube 40 is closed, atmosphere is admitted to the interior of the valve 21 in such proportions as to prevent the valve from being materially lifted off its seat dur' in the rotation of the engine by the starter. VVlhen the engine speeds up on its own explosions, however, the valve 21 will he lifted slightly off its seat by the increased suction'and the engine Wlll bepermitted to speed up in the manner which experience shows aids in warming u With the usual form of manually controlled choker, the engine cannot accelerate on its own explosions as freely as with this arrangement, because of the requirementto manually open the choker to permit the inflow of air.

After the en ine has started, the cam 45 must be rotated to a position in which the duct 44 is closed and thereafter the mixture may be gradually leaned by the rotation of the cam in a clockwise direction, thus admitting increasing amounts of air to the vacuum Venturi tube 40, causing slightly increased float chamber suction.

In the ordinary operation of this carburetor, a suction equivalent to substantially 40 inches of fuel in a manometer tube is maintained in the float chamber. If conditions arise where this degree of suction will not lift the fuel from the rear tank to the float chamber, the cam illustrated in Figure 4, if used, may be rotated to its extreme counter-clockwise position in which a small amount of air is admitted to the passage 44, thus preventing the valve 21 from being lifted as high as it ordinarily would be, thus increasing the suction within the float chamber to some predetermined amount greater than the normal l0 inches. Under these conditions, the power of the engine will be somewhat decreased because of the greater obstruction to the inflow of air. The cam edge 52 is formed so as to obstruct the entrance to the vacuum Venturi tube 4O just sufliciently to provide aproper float chamber suction to maintain a proper fuel feeding differential for correct mixture.

It will be understood that many features of the invention herein described are applicable to carburetors of the gravity feed type, though some of the features are applicable only to carburetors of the suction feed type. In order to convert this carburetor into one of the gravity feed type. it is necessary only that air be admitted to the float chamber to prevent the suction therein from rising to as high proportions as when the carburetor is used for suction delivery of fuel to the bowl. With this alteration, the spring 27 may have a less compression than when the carburetor is used for suction feed. All other features of the device may remain entirely unchanged.

While I have shown and described my invention with respect to certain details, it. is to be understood that these may be modified in many respects without departing from the spirit or scope of my invention.

What I claim is:

1. In a vacuum feed carburetor, a fuel reservoir, an induction passage, a Venturi tube extending from atmosphere into said induction passage, a connection between the upper part of the fuel reservoir and a con nesaeee stricted part of said Venturi tube for creating a suction in said reservoir for lifting fuel thereto, a manually operable cam member for variably restricting the entrance to said Venturi tube, a secondary air valve having a chamber therein wherein suction is effective for opening said valve, a piston within said valye, a duct extending through said piston and terminating beneath said cam, there being an opening through said cam member adapted to be moved into align-v ment with said duct to expose the duct to atmospheric pressure to prevent effective suction within the hollow valve.

2. In a carburetor, the combination with a secondary inlet of a hollow valve for controlling the flow of air through said inlet. a piston substantially closing the open end of said valve. a spring normally tending to close said valve. means to conduct the suction of the intake passage of the carburetor to the hollow portion of said valve for variously opening the valve, a duct extending from this hollow portion of said valve to external atmosphere. and a manually operable means for controlling the flow of air through said duct whereby the suction within said valve may be relieved to prevent the valve from opening.

3. In a vacuum feed carburetor. the combination with a fuel chamber to which fuel is drawn by suction from a low level source of supply, an induction passage for the carburetor. a secondary air valve controlling the flow of air into the carburetor. said secondary air valve being hollow and being opened by suction within the hollow part of said valve, a duct extending from the hollow part of said valve and a manually controlled member for limiting the flow of air through said duct whereby the suction for opening said secondary air valve will be decreased and the suction within the induction passage of the carburetor will be increased. a vacuum Venturi tube discharging into the induction passage of the carburetor and having its throat connected with the upper space of the fuel reservoir for creating a fuel lifting suction therein. the said manually controlled means being adapted to limit the flow of air to said Venturi tube when moved to the position to limit the flow of air to said duct whereby the degree of suction in the float chamber may be controlled to provide a correct mixture of fuel and air when the manually controlled device is moved tothe position for limiting the flow of air to the air valve.

4. In a carburetor. the combination with a casing providing an induction passage, a valve for controlling the entrance. of air to said induction passage. a piston within said valve, the suction of the suction-producing means for the carburetor being conducted to the interior of said valve for opening the same, a duct extendingthrough said piston voir and the induction passage for deliverand communicating with .the external ating fuel thereto under the influence of the mos'phere for relieving the suction Within suction in the induction passage. said piston to revent the opening of the In witness whereof, I hereunto subscribe 6 valve, a manually operable cut-ofl' mechamy name this 3rd day of October, 1922.

-nism for openin and closin the external end of said duct whereby the valve-ma be MILFORD CHANDLER prevented from opening to provide a igh Witnesses: suction in the induction passage, a fuel res- EDNA V. GUSTAFSON, 10 ervoir connection between the fuel reser- Em J. BOURGEOIS.

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