US1945179A - Carburetor - Google Patents

Description

W. C. CARTER Jan. 30, 1934.

CARBURETQR Filed Dec. 23, 1929 2 Sheets-Sheet l W. C. CARTER Jan. 30, 1934.

CARBURETOR Filed Dec. 25, 1929 2 Sheets-Sheet 2 Patented Jan. 30, 1934 CARBURETOR William 0. Carter, Flint, Mich.

Application December 23, 1929 Serial No. 415,995

8 Claims.

This invention relates to carburetors of the type which have provision for causing the ratio or proportion of fuel relatively to air to be increased under certain conditions, so as to produce a carburetor that has a power range and an economy range.

One object of my present invention is to provide a carburetor of the general type mentioned, that has a novel means of simple construction for obtaining or producing the variation in the ratio between the fuel and the air supplied at different speeds or under different conditions of the motor on which the carburetor is used.

Another object is to provide a carburetor that is equipped with a novel choking mechanism, which is of such design that it permits the motor with which the carburetor is used to be started easily in extremely cold weather without liability, however, of overchoking the motor in warm weather, or in mild weather, in the event the operator in charge of the motor fails to quickly move the choking member into its open position after the motor has started firing.

And still another object is to provide a carburetor having a power range and an economy range, which is of such design that a cold motor can be operated on the power range when the motor is throttled down. Other objects and desirable features of my invention will be hereinafter pointed out.

To this end I have devised a carburetor that is similar in general design to the carburetor described in my pending application for patent Serial -No. 226,684, filed October 17, 1927, which matured to Patent 1,821,439 granted Nov. 10, 1931 but which has a number of new features both in details of construction and in principle of operation, which make it an improvement on the carburetor of my said pending application. In my -10 present carburetor the suction or vacuum which exists in the main passageway above the throttle valve is used in a novel way to vary the ratio or proportion of fuel to air under different operating conditions or in different positions of the throttle valve. The carburetor is also equipped with a choking mechanism which practically eliminates the possibility of the motor being overchoked or stalled, due to carelessness or inattention on the part of the operator when the motor is being started. Still another novel feature of my present carburetor is an accelerating pump operatively connected with the throttle valve and arranged so as to discharge fuel from a chamber to which fuel feeds by gravity from the float chamber only when the motor is at rest or when there is a relatively slight flow of air through the carburetor.

Figure 1 of the drawings is a side elevational view, partly broken away, of a carburetor embodying my present invention. 7

Figure 2 is a top plan view of said carburetor.

Figure 3 is a vertical sectional view of the carburetor, taken on the line 3-3 of Figure 2,1ooking in the direction indicated by the arrows.

Figure 4 is a horizontal sectional View, taken on the line 44 of Figure 3, looking in the direction indicated by the arrows.

Figure 5 is a top plan view of thefloat chamber casting, showing the horizontally-disposed plate that forms the top wall of certain passageways which are formed in the upper face of the top wall of the float chamber.

Figure 6 is a vertical sectional View of the float chamber casting, taken at substantially rightangles to Figure 3, on the line 66 of Figure '5, looking in the direction indicated by the arrows.

Figure 7 is a horizontal sectional view, taken on the line 7-7 of Figure 6, looking in the direction indicated by the arrows. I

Figure 7a is a perspective View of the adjustable member that forms part of the upper endportion of the idle fuel supply duct that delivers fuel to the main passageway of the carburetor above the throttle valve.

Figure 8 is a side elevational view of the throttle valve lever, taken on the line 8- -8 of Figure 1,1 looking in the direction indicated by the arrows; and

Figure 9 is a side elevational View of the manually-operated device that is used to shift or adjust the choking member.

Referring to the drawings, which illustrate the preferred form of my invention, A designates the main passageway of the carburetor, which is herein illustrated as being formed by a verticallydisposed bore in a casting 1 that constitutes the main body of the carburetor, B designates a throttle valve of the oscillating type arranged adjacent the upper end of said main passageway, C designates a main air chamber in the body casting 1 provided with a tubular inlet 2 to which a conventional air cleaner can be connected, if desired, and D designates a choking member constructed preferably in the form of a venturi which I is arranged in the main passageway A in such a manner that said choking member can be moved downwardly to cause the b'ottom'edge 3 of same to contact with a horizontally-disposed plate 4 at the bottom of the main air chamber C, and thus prevent air from flowing directly from the open position, as shown in Figure 3.

fuel under certain operating conditions.

chamber C into the venturi and thence upwardly to the main passageway A. The throttle valve shaft 5 is provided with an arm 6 that is adapted to be connected with an operating mechanism by means of which the operator in charge of the motor on which the carburetor is used can easily change the position of the throttle valve, and means is provided for enabling the operator to adjust the choking member D or move said choking member towards and away from its closed position. Various means may be used to adjust or shift the choking member, the means herein illustrated consisting of an oscillating device '7 mounted in the body casting 1 and provided at one end with an eccentrically-disposed pin 8 which fits in a hole in the choking member D and provided at its opposite end with a spindle 9 equipped with an arm 10 to which a Bowden wire 11 or other suitable actuating device is connected, as shown in Figure 9.

The float chamber 1 E of the carburetor is formed in a casting that is arranged under the body casting 1 and combined with same in any preferred or suitable way. As shown in Figure 3, the float chamber E is of annular form and is provided with a horizontally-disposed top wall 12 that is integrally connected to a cylindrical outer wall 13 and to a cylindrical inner wall 14, said outer and inner walls being arranged in concentric relation. A vertically-disposed web F which is arranged transversely of the space inside of the inner cylindrical wall 14 of the float chamher, as shown in Figure 7, is used to form a number of passages and also a support for a tubular member G that projects upwardly into the venturi D, said tubular member G being so proportioned that the upper end of same terminates at or adjacent to the contracted portion of the venturi- D when said venturi is in .its raised or Usually, the center web F of the float chamber casting will be provided with a bulged central portion, as shown in Figure '7, that co-operates with the cylindrical wall 14, inside of which it is arranged to. form an accelerating well or reservoir H that is adapted to receive liquid fuel, the upper end of said reservoirH communicating with air passages-1.5 formed in the top wall 12 of the float chamber, as shown in Figure 6. The horizontally disposed plate 4, previously referred to, against which the bottom edge of the choking member D bears when said choking member is in its fully closed position, forms the top wall of the air passages. 15 just. referred to, and the peripheral edge of said plate 4 is spaced away from the side walls of the recesses in the top of the float chambenthat constitutes the air passages 15, so that aircan. flow freely-fromthe main air chamber 0 into the air passages 15, and. thence downwardly'into the accelerating reservoir H, as indicated. bythe arrows :c in Figure 6. At the lower end of, the web F is a center bore or space which forms part of the accelerating well H, and at the upper-endv of said center bore is a horizontallydisposed wall or partition 17 in which an orifice 18-. is, formed at a point in longitudinal alignment with: thetubular, member (3-, as shown in Figure 3,,so,as ,topermit fuel and air to pass from the reservoir H upwardly through the tubular mem- "berG, The orifice, 18 forms inv effect a restriction inthe passageway leading tothe venturi D that producesa strong suction on the fuel supplying device of the carburetor, and thus causes said device to .deliver a relatively great quantity of Vertically-disposed slots 19 are formed in the portions of the web F that are positioned in the accelerating reservoir H, so as to permit the air which flows downwardly into the accelerating reservoir H to travel inwardly to the center bore at the lower end of the web F, and thence upwardly through the orifice 18 at the lower end of the tubular member G, the slots 19 being so positioned that the normal level of the fuel in the accelerating well H will be a trifle below the upper ends of the slots 19, as indicated by the dot and dash line in Figure 3.

The top 12 of the float chamber is also provided with two additional passages 20 and 21 that have no communication with each other and no communication with the air passages 15 previously described. These separate passages 20 and 21 are arranged radially with respect to the center tubular member G of the carburetor and are disposed diametrically opposite each other, as shown in broken lines in Figure 5. Said passages are produced by forming recesses in the upper surface of the top 12 of the float chamber.

and using the plate 1, previously described, as a closure for said recesses. One of said passages,

to wit, the passage 20, is used to admit air to air.

ports 22, formed in the lower end of the tubular member G at a point just above the orifice 18 in.

of the carburetor, which is herein illustrated as. consisting of a fuel supply device I provided with" an orifice through which. fuel passes from the, float chamber into the lower end of the passage.

23. The supply of fuel to the accelerating reservoir H is obtained by a lateral port 24, shown in full lines in Figure 3 and in dotted lines in Figure '7, that leads to the accelerating reservoir-H" from the lower end of said passage 23.

When themotor is operating under a load andwith the throttle valve set in its open position, air

is drawn from the main air chamber C down through the accelerating reservoir H by way of passages 15, wherein said stream of air picks'up fuel and carries same upwardly through the orifice l8, and thence upwardly through thetubular member G. Due to the restricted size of said orifice 18, the jet of air and fuel discharging upwardly through the orifice 18 exerts a siphoning action onthe ports 22 in the lowerend of the tubular member G, with the result that theifuelsupplying device I is subjected to a suction of sufficient intensity to cause said device I to delivera relatively great quantity of fuel to the passageway 23. In order that the quantity of fuelsupplied by the device I will be reduced automatically when the load on the motor is reduced, and thus cause the carburetor to operate on the economy range, I have constructed the carburetor in such a way that the increase in the vacuum above the soon as the valve J opens the quantity of fuel delivered by the device I diminishes, thereby effecting a considerable saving in the consumption of fuel. When the suction in the center tubular member G is not great enough to exert a siphoning action on the fuel supply device I, the fuel which said device I delivers to the passageway 23 will escape laterally from same through the port 24 into the accelerating reservoir H and build up in said reservoir to the approximate level shown in Figure 3.

The valve J just referred to is herein illustrated as being formed by a vertically-disposed plunger mounted in the body casting 1 of the carburetor and provided at its lower end with a part that acts as a closure for an air port 25 formed in the horizontally-disposed plate 4. The upper end portion of said plunger is positioned in a vertically-disposed bore 26 in the body casting, and thus constitutes in effect a piston which will move upwardly when subjected to a suction of a certain approximate intensity existing in the upper end portion of said bore 26. The valve J is held seated by a spring 27 that exerts a down ward thrust on same. Any suitable means may be used for causing the suction or vacuum that exists in the main passageway A above the throttle valve to be exerted on the valve J, so as to move said valve J into its open position against the force of the spring 27. In the carburetor herein shown the main passageway A is provided adjacent its upper end with an annular groove 28 (see Figure 3) and the portion of the body casting 1 in which the main passageway is formed is provided with one or more vertically-disposed ducts 29 that lead downwardly from said annular groove, as shown in broken lines in Figure 3, and terminate in a counterbore in the body casting 1 that receives an enlarged intermediate portion of the choking member D. On the top face of the enlarged intermediate portion of the choking member D is a segmental groove 30 that is used to establish communication between the ducts 29. previously referred to, and a duct 31 that leads to the bore 26 in the body casting that receives the piston-like upper end portion of the valve J Consequently, the suction or partial vacuum existing in the main passageway A above the throttle valve under certain operating conditions will be exerted on the upper end of the valve J through the ducts 29 in the body casting. segmental groove 30 in the enlarged intermediate portion of the choking member D, and duct 31 in the body casting. Under certain approximate loads and in certain positions of the throttle valve, said suction or partial vacuum will cause the valve J to open and permit air to enter the lower end of the tubular member G through the ports 22 in same. In order that the carburetor will operate on the power range when the motor is being started or when the choking member D is arranged in its partly open position, I provide the choking member D with one or more air ports 32 that extend transversely through said member above the enlarged'intermediate portion of same, so as to permit air to pass from the interior of said choking member into the bore 26 in the body casting, and thus destroy or break the suction in said bore which otherwise would hold the valve J in its open position.

The passage 21 in the top of the float chamber is used to form part of an idle fuel supply duct through which fuel is introduced into the main passageway A of the carburetor at a point in proximity to the peripheral edge of the throttle valve at idle speeds of the motor, as described in my pending application Serial No. 226,684. Said passage 21 communicates at its inner end with a vertically-disposed bore 33 in the web F of the float chamber casting that leads upwardly from a shallow annular reservoir K formed in the bottom face of said web, and the outer end of said passage 21 communicates with a fuel tube 34, arranged vertically in the body casting, and which forms a part of said idle fuel supply duct. The upper end portion of said idle fuel supply duct may be constructed in the manner described in my said pending application for patent, or in any other suitable way.

by a vertically-disposed bar-like member 35 (shown in Figure 7a) that is positioned in an open-sided vertically-disposed groove formed in the side wall of the main passageway A, and having one of its inner edges or corners beveled at 36 so that when said member 35 is arranged in operative position, there will be a fuel duct or passageway between the beveled edge 36 of same and the groove in the body casting in which said member is positioned, said duct having a lateral outlet leading into the main passageway A above the throttle valve. While I prefer to use a bar or member 35 of substantially square cross section and arrange said member in the open-sided groove formed vertically in the body casting 1 at one side of the main air passageway A, it is not absolutely essential that the member 35 and groove in which it is positioned be of the particular cross sectional shape herein shown. The essential thing, so far as this feature of my invention is concerned, is that the upper portion In the carburetor herein shown the upper end portion of said duct is formed of the idle fuel duct of the carburetor be formed by co-acting portions on the body casting and on a solid or substantially bar-like member positioned in said casting and having a portion of its surface shaped so that it will be spaced away from the body casting to constitute a duct or fuel passageway. Preferably, the lateral outlet leading from said duct is formed by a notch or groove 3'7 formed in one side of the member 35. In order that the upper end of the idle fuel supply duct may be adjusted accurately with relation to thethrottle valve B, means is provided for raising and lowering the member 35, said means being.

means of a spring-pressed plunger 38, and any' suitable means can be used to retain the member 35 in the'groove in the body casting in which said member is positioned, such as a horizontally-disposed split expansion ring 41 (see Figure 3) ar ranged in the side wall of the main passageway A in such a way that it will engage the member 35 and retain said member in the groove provided for same in the body casting. As previously stated, the bore 33 which constitutes the lower end portion of the idle fuel supply duct leads from an annular chamber or reservoir K. Instead of relying on the main accelerating reservoir H to supply fuel to said chamber K, I have provided the carburetor with a separate fuel supplying device 42 for admitting fuel to the chamber K, said fuel supplying device 42 being arranged in such a way that the fuel in the float chamber can escape freely through the device 42 and enter the shallow chamber K which constitutes the The actuating" source of supply of fuel for the idle fuel supply duct of the carburetor.

Another feature of my present carburetor which I believe to be novel is a valve L that is used to automatically admit air to the main passageway A of the carburetor in the operation of starting the motor in cold weather, so as to eliminate the possibility of the motor stalling or becoming overchoked, in the event the operator fails to quickly open the choking member D after the motor has started firing. This valve L can be: constructed and arranged in various ways without departing from the spirit of my invention. It is herein illustrated as a valve of the pop action type arranged on the top side of the horizontally-disposed plate 4, previously referred to, so as to cover one or more air ports 43 in said plate through. which air can pass upwardly fromv the passages 15 into the interior of the choking member D when said valve L opens, as

hereinafter described. The valve L is normally held seated by a spring 44, shown in Figure 3, and the underside of said valve L is provided with one or more annular grooves 45 that reduce the area of the seating face of said valve sufficiently to produce a valve of the pop action type that will remain in its open position after said valve has been pulled upwardly off its seat by a suction exerted on the top face of said valve. In starting the motor in cold weather the operator manipulates the actuating device 11 of the choking member D in such a way as to move said choking member D downwardly into engagement with the plate 4, thereby cutting off communication between the interior of the choking member D and the main air chamber C of the carburetor. The suction that is created on the interior of the choking-member D when the motor is cranked either manually or by a mechanically or electrically operated cranking device, is not sufficient to "lift the valve L from its seat, but is of sumcient force, however, to draw a rich mixture upwardly through the tubular member G of the carburetor. As soon as the motor starts firing, however, the

m suction on-the interior of the choking member D increases, with the result that the valve L will the chokmg member D to its open position or move upwardly off its seat and permit air to flow upwardly into the interior of the choking member D from the air passages 15 through the air ports 43, thereby reducing the richness of the mixture and preventing the motor from stalling or stopping, as sooften occurs with carburetors of conventional design, if the operator fails to quickly open the choking member after the motor has started firing. As soon as the operator restores moves said choking member away from its closed position, the valve L will seat automatically under the influence of its spring 44, thus causing the directionof travel of the air flowing through "the passages 15 to be changed and diverted downwardly into the accelerating reservoir H.

'I'hev carburetor is equipped with an air pump M that is used to force a charge of fuel under a relatively high pressure upwardly through the "center tubular member G of the carburetor, so

as to produce an accelerating charge that is sure to reach the main passageway A of the carburetor. Said pump M is of the general type or design described in my pending application Serial No. 359,096, filed April 29, 1929, which matured to Patent 1,856,464 granted May 3, 1932, but in my present carburetor a novel means is provided for. holding the charge of fuel which said pump forces into the main passageway. Briefly stated,

my present carburetor is constructed in such' a manner that when thethrottle valve of. the. carburetoris moved away from its closed position,v

the pump M will force an accelerating charge of fuel upwardly through the tubular member G,

possibility of the main passageway A receiving.

a double accelerating charge when the throttle valve is opened only part way and subsequently shifted into its wide open or approximately wide open position. As. shown in Figure 3, the bottom of. the float chamber E is formed by a separate casting N that is retained in position by a nut 46 mounted on a nipple 47 that is screwed into- .the lower end of the center bore of the float.

ber N that is adapted to hold a chargeof fuel which I will refer to as a pump accelerating charge, and means is provided for causing said chamber N to fill with fuel only when the motor is at rest or is idling at such a speed that there is a relatively slight flow of air through the carburetor. the means that governs or controls the admission of fuel to the chamber N which holds the pump accelerating charge, consists of a check valve 48 mounted in the bottom of the float chamber in a passageway 49 that leads to the chamber N, as shown clearly in Figure 3. The chamber N will fill by gravity from the float chamber E, and when the throttle valve B is moved away from its closed position, the pump M will cause a stream of air under pressure to enter In the carburetor herein illustrated the chamber N, through an outlet 49 leading" from the pump, and thus cause the fuel in the reservoir N to escape from said reservoir through a port 50 in the. nipple 47, and thence flow upwardly through a discharge nozzle 51 into the tubular member G up through which said-accelerating charge is forced under a high pressure into the main passageway A of the carburetor. The pump M is provided with a piston 52 that is rockably mounted on a support 53, and the'cyL inder54 that receives said piston is connected with the throttle valve operating mechanism in such a way that when saidoperating mechanism is actuated, the cylinder 54 will move downwardly, and thus compress the air in said cylinder and force said air into the chamber N, as previously described. As shown in Figure 3, the float chamber E is provided with an annular float E".

that controls a needle valve 55 which governs the admission of fuel to thefloat chamber from: a

supply line 56. Due to the fact that the chamber N fills by gravity from the float chamber, it isv preferable that some means be employed for holding the valve 48 closed or in such. a condition that fuel will not pass from the float chamber into the chamber N after the engine has attained such a speed that an accelerating charge 1.

is not necessary, for otherwise, the chamber N would fill with fuel, and thus cause another ac-' back and forth slightly after the desired speed- In' the carburetor herein sult consists of a port 57 which leads from the upper end of the float chamber E to the main air chamber C of the carburetor, said port 57 .causing the suction which exists in the main air chamber C when the engine is operating at a speed high enough to make an accelerating charge unnecessary, to be exerted on the fuel in the float chamber E in such a way that the check valve 48 will be held closed or in a position to out 01f the passage of fuel from the float chamber into the chamber N that receives the pump accelerating charge. When the motor is stopped, or when the throttle valve "m moved into such a position that there is only a relatively slight flow of air through the air chamber C of the carburetor, the check valve 48 will open or move automatically into such a position that another charge of fuel can pass from the float chamber into the chamber N, and thus be in readiness to be forced upwardly through the center tubular member G of the carburetor when the throttle valve is thereafter moved away from its open posi- In a carburetor of the construction above described the device I which constitutes the main source of fuel supply is controlled or governed by the vacuum existing above the throttle valve in such a Way that the supply of fuel will be accurately regulated to give a rich mixture when the motor is pulling a load, and to give an economical mixture when the motor is in operation, but not under a heavy load. When the motor is not subjected to a load the valve J is held in its open position by the vacuum existing above the throttle valve, and hence, sufficient air will be drawn into the passage 21 to prevent the fuel supplying device I from being subjected to a suction of sufiicient intensity to cause it to deliver a relatively great quantity of fuel. However, when the valve J closes, due to a diminution in the suction of vacuum existing above the throttle'valve, the admission of air to the ports 22 in the lower end of the tubular member G is interrupted, with the result that the full force of the suction existing in the tubular member G is exerted on the fuel supplying device I, thereby causing a relatively great quantity of fuel to be'delivered by said device'I. Under a load with the throttle valve open, air is drawn from the main air chamber C into the passages 15, then downwardly into the accelerating-well H, and thence'upwardly through the tubular member G, through the orifice 18 at the lower end of said member, the upward flow of the stream of air and fuel through the orifice 18 exerting a siphoning action on the ports 22, with the result that the discharge of fuel from the fuel supplying device I will be increased. When the load on the motor is reduced, the vacuum above the throttle valve increases, thereby causing the valve J to open and permit air to rush through the ports 22, thus breaking or destroying the siphoning i action and effecting considerable economy in the fuel supplied by the device I.

In the operation of starting the motor the choking member D is moved downwardly into its closed position, so as to prevent the air in the main air chamber C from passing directly upwardly through the venturi of the carburetor. During the cranking operation the-suction that is created in the center tubular member G causes air to flow downwardly through the air passages 15, pick up the fuel in the accelerating reservoir i-I so as to produce a rich charge,

and flow upwardly through the main passageway A of the carburetor. At such times the valve that the ports 32 in the choking member D prevent the valve J from being subjected to a suction sufficient to move said valve into its open position, and at such times the pop action valve L remains seated, due to the fact that the suction which exists in the interior of the choking member D is not sufficient to overcome the force of the spring 44 which holds the valve L in its closed position. However, as soon as the motor starts firing the suction on the interior of the choking member D increases sufiiciently to cause the valve L to pop open and permit air to pass from the main air chamber C into the interior of the choking member D through the ports 43, thereby supplying sufficient additional air to the motor to prevent the motor from stopping or stalling before the operator has had a chance to restore the choking member D to its open position. This feature of my carburetor adds greatly to its utility and overcomes a serious inherent defect of conventional carburetors, as the valve L permits the carburetor to be designed so that it can be easily started in extremely cold Weather, and without liability of having the motor stall or stop in starting the same in mild weather in the event the operator does not open the choking member immediately after the motor has started firing.

The separate and distinct chamber N for holding the pump accelerating charge and the novel means that I have devised for supplying fuel to said reservoir also make my carburetor a decided improvement on conventional carburetors of the kind that are equipped with anaccelerating pump operatively connected with the throttle valve. In my present carburetor a prolonged accelerating charge will be forced into the main passageway of the carburetor under considerable pressure, when the throttle valve is moved away from its closed position, but if the throttle is stopped short of its Wide open position and thereafter moved from an intermediate position into its wide open or approximately wide open position, there is no liability of an additional accelerating charge being forced into the main passageway by the pump, due to the fact that the chamber N can fill only Whenthe motor is stopped or when there is a relatively slight flow of air through the carburetor. Under ordinary running conditions the air circulates through the main air chamber C at a sufficient velocity to create a suction in the float chamber E, by means of the port 5'], that will hold the check valve 48 closed, and thus prevent the fuel from passing from the float chamber into the pump accelerating chamber N.

At idling speeds fuel is introduced into the main passageway A above the throttle valve by the idle fuel supply duct which leads from a shallow chamber K, as described in my pending application Serial No. 226,684, but in my present carburetor a separate and distinct fuel supplying device 42 is provided for admitting fuel to the chamber K directly from the float chamber E, and the upper end portion of the idle fuel supply duct is formed in a novel manner that reduces the cost and facilitates the manufacture of the carbu adequate supply of fuel for the duct WhiCh'diS- motor, a manuallyoperable means for enabling the circulation of air from said chamber to said .choking member to be reduced to facilitate starting the motor, and a choke relief valve arranged concentrically with relation to said choking member, andcontrolled or governed by the internal suction of said choking member, for automatically re-establishing the circulation of air to said choking member when the motor starts firing, even though the operator has not released said manually operable means.

'2. A carburetor provided with a venturi, means for enabling said venturi to be shifted into adifferent position during the operation of cranking the motor so as to cause a rich mixture to be sup- :plied to the motor, and means governed by the internal pressures in said venturi for causing ad- 'ditional air to be supplied to the main passageway .for enabling the operator to cut off the direct passage of air from said main air chamber to said choking member during the operation of cranking the motor, and a pop valve arranged concentrically with relation to said choking member, governed by the suction in said choking member, for re-establishing a circulation of air from said air chamber "to said choking member when the motor starts firing.

4. In a carburetor, the combination of a main passageway, a main air chamber, a choking member that forms a passageway for air traveling from said airchamber into said main passageway under normal operating conditions, means for enabling said choking member to be moved into a closed position to cut off the circulation of air to same from said air chamber, and a'spring-seated air valve governed by the suction inside of said choking member when said member is closed, for

automatically re-establishing a circulation'of air from said air chamber into said chokingmemb'er when the motor starts firing.

5. A carburetor provided with a main passageway, a main air chamber, a choking member of venturi formarranged in said main passageway so asto form an inlet for same from said main air chamber, means for moving said choking member into a closed position so as to cutoff: direct circulation of air into same from said air cham ber, and an air valve combined with said choking member in such a way that when the motorstarts firing when said choking member is in its closed position, said air valve will openand thus-automatically re-establish a circulation of air from the air chamber into said choking-member.

6. A carburetor provided with a main passageway, a throttle valve, an accelerating reservoir, a fuelsupply device, means whereby the suction in the main passageway will cause a stream of-aircto enter said reservoir, pick up fuel in same and carry said fuel into the main passageway, means for utilizing the stream of air and fuel flowing to the-main passageway to exert a siphoning action on said fuel supplying device, and a valve governed by the vacuum above the throttle valve for adding additional air to the stream flowing to the main passageway so as to reduce the dise charge of fuel from said fuel supplying device.

7. A carburetor provided with an air valve for supplying air so as to diminish the discharge of fuel from the main fuel supply device of the carburetor, means for utilizing the vacuum sexisting above the throttle valve for governing said air valve, a choking device for enriching the mixture supplied to the mot-or during the operation of crankingthe motor, and means for preventingthe vacuum above the throttle valve from beingexerted on said air valve to influence the action-of same when said choking device is inother than-its fully open position.

8. Acarburetor provided with amainpassageway, a throttle valve, a tubular member through which air and fuel enter said main passageway, said tubular member having a restriction, a main fuel supply device, ports in said tubular member above said restriction for exerting a, siphoning action on said fuel supply device, an air passage leading to said ports, and a spring-seated valve for governing the'admissio-n of airto saidairpas: sage, adapted-to be opened and maintainedinan open position by the vacuum'that exists above the throttle valve under certain operating conditions.

WILLIAM C. CARTER.

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