US2086058A - Carburetor - Google Patents

Description

July 6, 1937. VAUGHAN 2,086,058 I GARBURIETQR Filed Jan. 21, 19:55 4 Sheets-Sheet 1 I INVN R 762 ATTOY July 6, 1937.

H. P. VAUGHAN CARBURETOR Filed Jan. 21, 1933 4 Sheets-Sheet? Fig 7 I avmenfoz @3 4, I

Patented July 6, 1937 GARBURETOR Appiication January 21, 1933, Serial No. 652,779

19 Ciaims.

My invention relates to new and useful improvements in carburetors, and more particularly to a carburetor for supplying fuel to an internal combustion engine. In starting an internal oombustion engine, it is desirable and often necessary in cold weather to increase the richness of the fuel mixture. This may be accomplished by the use of a priming device di charging beyond the throttle valve for supplementing the supply of fuel from the main nozzle. In using such a priming device, I have found it to be more efficient if the engine is cranked with closed throttle as this permits a minimum admission of air and maximum suction on the priming fuel; but in order to sustain the running of the engine upon the first explosion or firing, the volume of the supplied mixture must be quickly increased substantially coincidently with the first explosion and its richness be simultaneously decreased in order to maintain the engine in operation.

It is, therefore, an object of my invention to provide means which will operate automatically to provide sufiicient air to maintain operation of the engine when the same has fired.

Another object is to provide means operable upon actuation of the priming device to render the automatic" air supply means operative.

Another object is to provide means for supplying air from the mixing chamber to the engine when the throttle Valve is in closed position so that any fuel which may be supplied to the mixing chamber will be discharged therefrom with the air. I

The invention consists in the improved con- 5 struction 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 drawings, to be taken as a part of this specification, I have fully and clearly illustrated a preferred embodiment of my invention, in which drawings- Figure 1 is a view in side elevation and partly in section of a carburetor embodying my invention;

Fig. 2 is a detail'view showing the construction of the main air and fuel inlet means;

Fig. 3 is a top plan view of the carburetor partially in horizontal section;

Fig. 4 is a view in end elevation and partially in section on the line 4-4 of Fig. 3;

Fig. 5 is a detail section on the line 5-5 of Fig. 4;

Fig. 6 is a detail view in vertical section on the line G6 of Fig. 3;

Fig. '7 is a view similar to that of Fig. 6 but showing certain of the parts in a position assumed during operation of the carburetor;

of Fig. 1, and

Fig. 9 is a diagrammatic view in section and partly in perspective, showing the internal construction of the carburetor.

Referring to the drawings by characters of reference, l designates, generally, the body or casing of a carburetor having a passageway therethrough, which includes an air inlet 2, an air inlet chamber 3, a mixing chamber 4, and a mixture outlet 5. Within the chamber 3 there is a sleeve member 6 containing a dash-pot chamber i above which the sleeve member is of reduced internal diameter, as at 8, to provide a guide means. Reciprocable in the reduced sleeve portion 8, there is a tubular nozzle member 9 which extends downward into the chamber 1 and which is provided therein with a piston l; Positioned within the chamber 7, there is a coil spring II which is held under compression between the top wall of the chamber l and the piston I 0 and normally tends to move the member 9 into the chamber l. The other end of the member 9 extends beyond the sleeve member 6 and is provided with a nozzle I2 having a port l3 estab-. lishing communication between the bore of the member 9 and the mixing chamber 4, and which comprises the main fuel jet. Thechambers 3 and 4 are separated by suction operated valve members l4, l5, preferably in the form of substantially rectangular plates which are journaled on shafts it supported in the side walls of the casing I, and which are provided at their free edges with cooperating recesses H which receive the end of the nozzle I2. The recesses II are preferably substantially semi-cylindrical and provide an annular air flow space around the nozzle 52 and between chambers 3 and 4. The members M, 5 preferably engage each other at the sides of the'nozzle i2 and are positioned between substantially parallel guide plates! SWhich cooperate with the side edges of the valve members I4, i5.

to close communication between the chambers 3 and 4. Within the passageway and separating the chamber 4 from the outlet is a throttle valve It, preferably of a plate or butterfly type, which is fixed on a shaft 20- journaled in the side walls of the casing l and projecting therethrough at one end, as at 2h The chamber 1 is in communication through a passage 22 with the interior of a constant level float chamber or reservoir 23, preferably rigid with the casing l. The chamber 23 is provided with a fuel inlet passage 23 which is controlled by a valve 24 which may be actuated by a float, not shown, as is well-' known in the art for maintaining a. substantially constant liquid level'of fuel in the reservoir 23..

A metering valve 25 is positioned in the chamber 1 and extends upwardly into the bore of the member 9, being adjustably supported in a plug means 25 secured in thebo-ttom wall of the casing 1, the means '25 forming the bottom wall of the chamber I. The valve members I4, I5 are provided with operating arms 25 which project from the under-sides thereof and which terminate at their free ends in an annular recess 21 in the nozzle I2 so that movement of the members I4, I5 into parting relation will act through the members 26 to lift the tube member 9 relative tothe metering pin 25 and thereby increase the annular flow space within the member 9 and around the metering pin 25.

The casing I supports a housing 28 which is positioned above the reservoir 23 and which has a substantially cylindrical internal chamber 29, preferably a vertical open-ended bore. Positioned within the bore 29 is a substantially cylindrical valve member 39 containing a fluid chamber 3I which is open at its upper end and receives a reciprocable piston valve 32 which serves to close the upper end of the chamber 3I. Secured to the under-side of the valve 32, there is a tubular conduit member 33 which extends downward through an aperture 34 in the bottom wall of thechamber 3! and terminates within a hollow housing 35 positioned within the reservoir 23. The housing 35 is provided at its top portion with a marginal flange 35 which 'seats on the cover member 31 of the reservoir 23, the housing 35 extending downward into the chamber 23 through an aperture in the member 3! and being closed at its upper end by a cover member 31 The tubular member 33 comprises a pump plunger rod and operatively engages a piston 38 which has a port 38 therethrough registering with the bore of the tubular member 33. The interior of i the housing 35 comprises a pump chamber 49 which receives the piston 38 for vertical reciprocation. The piston 38 is normally held in engagement with the rod 33 by a coil spring 39 engaging the under-side of the piston 38 and seating at its bottom end on the bottom wall of the chamber 48. The chamber 49 is provided with an inlet port 4| in the bottom wall of the housing 35 and adjacent the bottom wall of the reservoir 23. This port M is preferably controlled by a check valve 42 which opens to permit flow into the chamber 49 but which closes upon the pumping stroke of the piston 38. The valve member 39 is provided with an operating arm or lever 43 having a plate portion 44 surrounding the lower end of the valve member 30. The portion 44 is fixed in any suitable manner against rotation relative to the member 39 but is movable longitudinally thereof. The lever'43 is provided with spaced stops 45, 45 which cooperate with anabutment 41, which may be one of the reservoir cover member securing screws, and which serves to limit rotation of the valve member 39. The lever 43 is normally held with the stop 45 in engagement with the abutment 41 by a spring 48 which surrounds the lower end of the valve member 39 and has one end 49 engaging the arm 43 and its other end 5!] bearing against the side wall of the casing I. The spring 48, being in the form of a helix, also serves to hold the housing 35 in position by expansion between the under-side of the housing 28 and the lever portion 44 which bears on the top face of the flange 36. The valve member 39 is held against longitudinal movement in the bore 29 by a screw 5! which is carried by the housing28 and seats at its inner end in an annular recess 52 in the valve member 39. The housing 28 contains an air inlet chamber 53 7 having an air inlet port 54 in its side wall open to atmosphere. The chamber 53 isipositioned at theiside of the chamber 3;! andathese chambers are normally in communication by registering ports 55, 53, but the ports are movable out of registry upon rotation of the valve member 39. In its lower portion the valve member 30 has a follow-up chamber 51 which is in communication with the chamber 53 by conduits 58, 59

which are maintained in communication with each other by the annular recess 52. The tubular member 33 is provided with a port 60 which is normally closed by the bottom wall of the chamber 3 I, but which is movable into the chamber 5i upon downward movement of the member 33 to thereby uncover the port 69 and establish communication between the chamber 51 and the bore of the member 33. The valve member 30 is provided with a plurality of ports BI, 62 of varying sizes which cooperate with a fuel jet or nozzle 63 extending from the bore 29 and terminating within the mixing chamber 4, the port 6| normally registering with the bore of the nozzle 63. The valve member 30 is also provided with a port 54 which is movable into registry with a conduit 65 which extends from the bore 29 to the outlet 5 on the outlet side of or posterior to the throttle I9. The tubular member 33 is provided with one or more ports 65 positioned in the chamber 3| and establishing communication between the bore of the member 33 and the chamber 3|. The piston 38 is operable by a lever 6'7 which seats at one end in a slot 68 formed in the side face of the valve member 32. The lever SI is journaled intermediate its ends on a pin 69 rigid with the casing I, and at its other end is engaged by a pin I0 carried by the throttle shaft operating member II which is rigidly secured to the projecting end 2I of the throttle shaft. The lever B! is provided with an aperture through which the shaft 29 extends, the aperture being of sufiicient dimension to permit operation of the lever.

In the side wall of the casing I, intermediate the ends of the throttle shaft 29, there is an opening I2 which extends above and below the edge of the throttle Valve when the throttle is in closed or idling position, so that the opening I2 provides a passageway establishing communication between the mixing chamber 4 and the outlet 5 around the throttle. 'The passageway I2 is controlled by a suction responsive member I3 having an end portion I4 defining a valve member which fits in the opening 12 and which substantially conforms to the wall of the chamber 4 and outlet 5. The opening or passageway I2 is in communication with the hollow interior of an extension or casing member I5 which pro-' jects from the casing I adjacent the housing 28. The bore of the extension I5 is provided with an outward facing shoulder I6 which surrounds the opening I2 and which cooperates with a peripheral shoulder 11 on the member I3 to limit inward movement of the member I4 to a position substantially flush with the wall of chamber 4. The rear face of the member I3 is provided with a recess I8, preferably cylindrical, in which is seated one end of a helical coil spring I9 which is held under compression thereagainst by a plug member 80 which serves to close the outer end of the extension I5. to exert a predetermined resistance to movement of member I3 such that the valve member 14 will be maintained closed at low cranking speeds, say for example below forty R. P. M. The plug member 89 is preferably screw-threaded into the extension I5 and has an axially projecting pin f8I which serves as a stop member for engage- The spring I9 is calibrated mentwith and to limit outward movement of the 75.

member 13, i. e.,' opening movement of valve member 14. The bore of the extension 15 provides a suction chamber 82 which is in communication by a conduit or passageway 83 with the bore 29. The member 13 is freely slidable in the bore of the extension 15 but is provided with a suficiently tight iit to prevent leakage around the same, that is, between itself and the inner wall of the chamber 32. The valve member is provided with a transverse slot 85 which normally communicates at one end with the passageway 83. The other end of the slot 84 registers with a port 85 through the wall of the housing 28 and opening to atmosphere. The housing 28 is provided with another port 86 which is communicable with the slot 84 but normally out of registry therewith and which opens from the bore 29 into the passageway 65.

The operation of my carburetor when applied to an internal combustion engine is as follows. When it is desired to start the engine, the lever 43 is rotated to bring the stop 46 into engagement 4 with the abutment 41 which will rotate the valve member 3Q. Rotation of the member'tli will move the port 55 out of registry with port 56 to cut off admission of air to the fluid chamber 3!. The port 64 will be moved into registry with the duct or passage 65 so that a conduit extending from the reservoir 23 to the outlet 5 will be established via the port 4|, chamber 48, bore of member 33, fluid chamber 3i, port 64, and passageway 65. Simultaneously with the registration of port 64 with passageway 65, the slot 84 will be moved into the dotted-line position shown in Fig. 5 to connect the passage or port 83 and the passage 86. In this position of the slot 84 the chamber 82 will be in communication with the passageway 65 and, therefore, the outlet 5. This rotation of the valve member 30 will also serve to move the ports 6i and 62 out of registry with the nozzle 63. If the engine is now cranked. with the throttle valve [9 in closed or idling position, the subatmospheric pressure created on the outlet side of the throttle valve will be transmitted through the conduit 65 and the bore of member 33 to the reservoir 23, which being open to atmosphere will cause a discharge of solid liquid fuel therefrom through the bore of member 33 and the passage 65 into the carburetor outlet 5. This solid liquid fuel which serves as a priming charge for the engine will be mixed with a very small quantity of air such as can pass the valve members [4, l5 when closed and the throttle valve I?! when in idling position. The subatmospheric pressure or suction created in the outlet 5 will be transmitted through the passageway 65, the passage 86, slot 84, and port 83 to the chamber 82, but the reduction in pressure in the chamber 82 will not be sufficient to cause movement of the valve member from its normal closed position in which the shoulders Ti and 76 are in engagement, as in Fig. 6. The resistance of the spring 19 to movement of the member 13 is predetermined with respect to the subatmospheric pressure created in the chamber 82 and the outlet 5 at cranking speeds so that at low engine cranking speeds the member 13 will not be moved from its normal position, Fig. 6, by the substantially atmospheric pressure existing in the mixing chamber l. As soon as the engine fires, the suddenly increased subatmospheric pressure in the outlet 5, due to the firing of the engine which, however, is less than the suction or subatmospheric pressure at engine idling speeds, will be transmitted to the chamber 82 so that the substantially atmospheric pressure in the mixing chamber 4 acting on the face of the valve member M will overcome the spring 19 and move the member '53 toward full-open valve position shown in Fig. 7, so that the passage 72 around the throttle will be open to an extent depending on the differential of pressures and forces acting on member-l3. The opened pas sage 12 will permit air from the mainair inlet 2 which may be mixed with some fuel from the main nozzle E2 to by-pass the throttle valve in sumcient quantity to mix with the liquid fuel discharged from passageway 65 to create the desired volume of rich mixture to sustain operation of the engine and bring it up to idling speed. As the enginge speed builds up, the valve member i l will move further open until limited by the stop 85 as the member 73 is responsive to the suction in outlet 5. Should the throttle be opened while the lever 43 is maintained in priming position, that is, with stop 46 engaging abutment ll, the ratio between the pressures acting on the member '53 on its passageway side, above and below the throttle valve, will be varied so that the spring 79 will move the member 73 from its open position toward and finally to the position of Fig. 6, but this will not aifect the operation of the engine as the main fuel jet will come into operation. If the throttle should be moved to closed or idling position after having been opened as above described, the member l3 will be returned by suction toward open position, 'Fig. 7, so that sufiicient air flow will be reestablished around the throttle to maintain engine operation. Except in extremely cold weather, the lever 43 will not be maintained in starting or priming position after the engine has fired but will be returned toward the position of Fig. 3 when the port 62, which is somewhat larger than port 6!, will come into registry with the nozzle 53. In this position of the lever 3 the air admission ports 55 and 56 will still be out of registry with each other so that the suction in the mixing chamber '3 will draw fuel from the reservoir through the bore of member 33 into the mixing chamber 4 through the port 62 and the nozzle 63. The slot 85 is preferably of such length that the passages 83 and 36 will be maintained in communication with each other when the portv 62 is in registry with the nozzle 63 so that the bypass passage l? will be maintained open when the throttle is inclosed or idling position. The discharge from the reservoir 23 through the port 62 into the mixing chamber is'sufiicient to supplement the discharge from the main nozzle jet P i3 to provide the desired rich mixture for warming-up operation of the engine. When the engine has been sufiiciently warmed up, the lever 43 is returned to normal position in which the stop 45 engages the abutment W. This movement of the lever 43 will cause the circumferential face of the valve member 30 to close the passage 86 and will bring the passage or slot 84 into communication with the atmospheric port 85. The chamber 82 will, therefore, be at atmospheric pressure through the port 85, slot 84, and port 83 so that the member 83 will be moved by the spring l9 to the position of Fig. 6, thereby closing the by-pass passage 72 and maintaining the same are such as to satisfy the mixing chamber suction on the nozzle 63, thereby preventing further discharge of fuel from the reservoir 23 through the bore of member33. As the throttle valve I9 is moved toward open position, the piston Valve 32 will cut off or close the port 55 at an engine speed corresponding, for example, to about 60 miles per hour, level road car speed. Closing of the port 55 will cause the. subatmospheric pressure in the mixing chamber to draw fuel from the reservoir through the bore of member 33, the port BI, and the nozzle 63, which will supply fuel supplemental to that from the main jet I3 sufficient to satisfy the high power demands of the engine. The fuel supplied by the nozzle 63 at high power demands will be mixed with air entering the bore of member 33 through the port 6!! which .will have been moved downward into the chamber 51, the air entering chamber 51 from chamber 53 through the passages 58 and 59. If the throttle is moved quickly to open position from closed or normal running position, the downward movement of the rod member 33 will move the piston 38 downward, closing the check valve 42 and expelling fuel from the chamber 40 through the bore of member 33 and the port 66 into the chamber 3!. Some of the fuel thus forced into the chamber 3! will pass through ports 55 and 56 into the chamber 53 and will drain therefrom through passages 58 and 59 into the chamber 51. This fuel collecting in the chamber 51 will be under atmospheric pressure and will be fed into the bore of member 33 when port 60 moves into chamber 5'! to: be discharged with and to supplement the fuel passing from the reservoir 23 through the bore of member 33. If the opening movement of the throttle valve is sufficient to cause the valve member 32 to close the port 55, the forced discharge of fuel from the pump chamber into the mixing chamber will be followed by the discharge of the emulsion comprising fuel from the chamber 4i} and air from the bleed port 60, as above described.

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

l. A carburetor of the character described, comprising a casing containing a mixing chamber having a mixture outlet, means to supply air to said chamber, means to supply fuel to said chamber, a throttle valve in said outlet, a fuel reservoir, a fuel supply conduit leading from said reservoir to said outlet beyond said throttle valve, a by-pass passage for transmitting fuel and air from said mixing chamber to said outlet when said throttle valve is closed, a valve in said by-pass passage and responsive to suction on the outlet side of said throttle valve, said responsive valve being closed when the pressure in said outlet is substantially atmospheric, and a spring seating against said responsive valve and positioned on the suction side thereof, said spring exerting a predetermined resistance to hold said responsive valve closed and to oppose opening movement of said responsive valve whereby upon engine cranking an exceedingly rich fuel mixture Will be supplied, the predetermined resistance of said spring being such that said responsive valve is closed at low engine cranking speeds and such that said spring is overcome at high engine cranking speeds which are less than cold engine idling speed whereby the necessary volume of fuel mixture to provide forcold engine operation will be admitted past said throttle valve upon firing of the engine.

2. A carburetor of the character described,

comprising a casing having a passageway therethrough with main air and fuel inlets, means to supplement the fuel supplied to said passageway by said main fuel inlet, a valve controlling said supplemental means, a throttle valve controlling the outlet from said passageway, a bypass passage communicable at its opposite ends with said passageway on the opposite sides of said throttle valve, a valve controlling said bypass passage, said by-pass controlling valve being responsive to subatmospheric pressure on the outlet side of said throttle valve thereby to open said by-pass passage, and means operable simultaneously to open said supplemental fuel valve and to subject said by-pass controlling valve to subatmospheric pressure'on the outlet side of said throttle valve.

3. A carburetor of the character described, comprising a casing having a passageway therethrough with main air and'fuel inlets, means to supplement the fuel supplied to said passageway by said main fuel inlet, a valve controlling said supplemental means, a throttle valve controlling the outlet from said passageway, a by-pass passage communicable at itsopposite ends with said passageway on the opposite sides of said throttle valve, a valve controlling said by-pass passage, said by-pass controlling valve being responsive to subatmospheric pressure on the outlet side of said throttle valve thereby to open said by-pass passage, a spring resisting opening movement of said suction responsive valve, the resistance of said spring being such as to maintain said suction responsive valve closed at low engine cranking speeds and to be overcome at higher engine speeds whereby to permit flow through said bypass passage, and means operable simultaneously to open said supplemental fuel valve and to subject said by-pass controlling valve to subatmospheric pressure on the outlet side of said throttle valve. r

4. A carburetor of the character described, comprising a casing having apassageway therethrough with main air and fuel inlets, a throttle valve controlling the outlet from said passageway, a casing member having a chamber therein communicable with said passageway on the inlet and outlet sides of said throttle valve, a suction operated valve member in said chamber and controlling communication between said chamber and said passageway, a conduit connecting said chamber and said passageway on the outlet side of said throttle valve, a valve controlling said last-named conduit, means to supply supplemental fuel to said passageway, a valve controlling said supplemental fuel supplying means, and means operable to open said secondnamed and said third-named valves.

5. A carburetor of the character described, comprising a casing having a passageway therethrough with main air and fuel inlets, a reservoir to supply fuel to said fuel inlet, a throttle valve controlling discharge from said passageway, a conduit extending from said reservoir to said passageway on the outlet side of said throttle valve, valve means controlling said conduit, a b-y-pass passage communicable at its opposite ends with said passageway on the opposite sides of said throttle valve, a valve controlling flow through said by-pass passage, means responsive to suction and operable to move said by-pass valve to open position to permit flow around said throttle valve, a suction conduit for subjecting said responsive means to suction in said passageway .on the outlet side of said throttle valve, a

valve controlling said suction conduit, and means operable to move said suction-conduit controlling valve to open position upon movement of said valve means to open position.

6. A carburetor of the character described, comp-rising a casing having a passageway therethrough with main air and fuel inlets, a fuel reservoir, a conduit connecting said reservoir and said fuel inlet, a throttle valve in said passageway, a casing member having an internal chamber, the side wall of said passageway having a port opening into said chamber and positioned substantially in the plane of the closed throttle valve whereby said port provides a by-pass passage around said throttle valve, a suction operated valve member reciprocable in said chamber and movable into said port to close the by-pass passage, a suction conduit leading from said chamber to said passageway on the outlet side of said throttle valve for subjecting said valve member to engine suction, and a valve controlling said suction conduit.

7. A carburetor of the character described, comprising a casing having a passageway therethrough with main air and fuel inlets, a fuel reservoir, a conduit connecting said reservoir and said fuel inlet, a throttle valve in said passageway, a casing member having an internal chamber, the side wall of said passageway having a port opening into said chamber and positioned substantially in the plane of the closed throttle valve thereby to provide a by-pass passage around said throttle valve, a suction operated valve member reciprocable in said chamber and movable into said port to close the by-pass passage, a suction conduit leading from said chamber to said passageway on the outlet side of said throttle valve for subjecting said valve member to engine suction, a valve in said suction conduit, a fuel supply duct for supplying fuel from said reservoir to said passageway on the outlet side of said throttle valve, a valve controlling discharge from said duct, and means interconnecting said duct controlling valve and said suction conduit valve.

8. A carburetor of the character described, comprising a casing having a passageway therethrough with main air and fuel inlets, a fuel reservoir, a conduit connecting said reservoir and said fuel inlet, a throttle valve in said passageway, a by-pass passage opening into said passageway on the opposite sides of said throttle valve, a casing member containing a suction chamber, a valve responsive to suction in said chamber and controlling flow through said by-pass passage, a fuel duct for supplying fuel from said reservoir to said passageway on the outlet side of said throttle valve, a valve controlling discharge from said duct, a conduit opening into said duct and into said chamber, a valve controlling transmission of suction from said duct to said chamber, and means interconnecting said last-named valve and said duct controlling valve.

9. A carburetor of the character described, comprising a casing having a passageway therethrough with main air and fuel inlets, a throttle valve controlling the outlet from said passageway, means to supply fuel to said passageway on the outlet side of said throttle valve, a by-pass passage around said throttle valve to transmit fuel and air from said main inlets to the outlet side of said throttle valve, a suction responsive valve member controlling said passage, a conduit for transmitting suction from said passageway on the outlet side of said throttle valve to said.

valve member, a rotary valve member having means controlling said fuel supply means and having means controlling said conduit, and means for operating said rotary valve.

10. A carburetor of the character described, comprising a casing having a passageway therethrough, main air and fuel supply means for said passageway, a throttle valve controlling discharge from said passageway, 21 by-passpassage operable to transmit fuel and air from said main supply means to said passageway on the outlet side of said throttle valve, a conduit to supply priming fuel to said passageway, a Valve in said conduit and operable to maintain said conduit closed during engine operation, a normally closed valve controlling said by-p-ass passage, and means operable said conduit valve to control operation of saidnormally closed valve, said normally closed valve being operable at engine firing speeds to open said by-pass passage whereby to supply fuel and air from said main supply means to said passageway on the outlet side of said throttle valve.

11. A carburetor of the character described, comprising a casing having a passageway therethrough, main air and fuel supply means for said passageway, a throttle valve controlling discharge from said passageway, a by-pass passage from and to said passageway around said throttle valve, means to supply priming fuel to said passageway, a valve controlling said priming fuel supply means, a normally closed suction operated valve controlling said by-pass passage and operable at engine firing speeds to open said passage whereby to supply fuel and air from said main supply means to said passageway on the outlet side of said throttle valve, and means operable simul-- taneously to open said priming fuel supply valve and to subject said suction operated valve to engine suction.

12. A carburetor of the" character described, comprising a casing having a passageway therethrough with main air and fuel inlets, a throt tle valve controlling discharge from said passageway, a fuel reservoir, a housing member having an internal bore, a valve member rotatable in said bore, a conduit leading from said bore to said passageway on the outlet side of said throttle valve, said valve member having a port regis terable with said conduit, means to supply fuel from said reservoir to said valve port, a by-pass passage opening into said passageway on the opposite sidesof said throttle valve, a suction responsive valve controlling flow through said passageway, a suction conduit leading from said passageway on the outlet side of said throttle valve to said bore, a suction conduit leading from said bore to said suction responsive valve, said valve member having a passageoperable to establish communication between said suction conduits when said valve port is in registry with said first-named conduit, said housing member having an air inlet to said bore cooperable with said valve member passage, means to rotate said valve memher to establish communication between said air inlet and said second-named suction conduit and simultaneously to move said valve member port out of registry with said first-named conduit, and a spring resisting opening movement of said suction responsive valve.

13. A carburetor of the character-described, comprising a casing having a passageway therethrough, a throttle valve controlling flow through said passageway, main air and fuel inlets discharging into said passageway on the inlet side of said throttle valve, supplemental means to supply fuel to said passageway on the outlet side of said throttle valve, said casing having a by-pass passage around said throttle valve and communicating with said passageway on the opposite sides of said throttle valve, a valve controlling flow through said by-pass passage and responsive to engine suction on the outlet side of said throttle valve, a valve member having one portion controlling said supplemental fuel supply means and having another portion controlling transmission of engine suction to said suction responsive valve, and means holding said responsive valve closed at low engine cranking speeds.

14. A carburetor of the character described, comprising a casing having a passageway therethrough, a throttle valve controlling flow through said passageway, main air and fuel inlets discharging into said passageway on the inlet side of said throttle valve, supplemental means to supply fuel to said passageway on the outlet side of said throttle valve, said casinghaving a'by-pass passage around said throttle valve and communicating with said passageway on the opposite sides of said throttle valve, a valve controlling'fiow through said by-pass passage and responsive to engine suction on the outlet side of said throttle valve, a conduit separate from said passage for transmitting engine suction to said suction responsive valve, a valve controlling said conduit, and means holding said by-pass controlling valve closed at low engine cranking speeds.

15. A carburetor of the character described, comprising a casing having a passageway therethrough, a throttle valve controlling flow through said passageway, main air and fuel inlets discharging into said passageway on the inlet side of said throttle valve, supplemental means to supply fuel to said passageway on the outlet side of said throttle valve, said casing having a by-pass passage around said throttle valve and communieating with said passageway on the opposite sides of said throttle valve, a valve controlling flow through said by-pass passage and responsive to engine suction on the outlet side of said throttle valve, means controlling transmission of engine suction to said suction responsive valve, a valve controlling said supplemental supply means, said last-named valve and said controlling means being operatively connected together, and means holding said suction responsive controlling valve closed at low engine cranking speeds.

16. A carburetor for supplying fuel mixture to an engine comprising a casing having a mixture passageway therethrough, means to supply air to said passageway, means to supply fuel to said passageway, a throttle valve controlling flow through said passageway and movable to a closed position wherein insufficient fuel mixture will be discharged from said passageway to maintain cold engine idling operation, means to increase the quantity of fuel mixture supplied to the engine to provide cold engine idling operation while said valve is maintained in said closed position, means responsive to suction created by the engine for controlling said last-named means, and means actuable at the will of an operator for controlling said responsive means.

17. A carburetor of the character described comprising a casing having a passageway therethrough with main air and fuel inlets, a throttle valve controlling the outlet from said passageway, a casing member having a chamber therein communicable with said passageway on the inlet and outlet sides of said throttle Valve whereby to by pass airand fuel from said main inlets around said throttle valve, a suction responsive valve member in said chamber and controlling flow therethrough, means to subject said valve member to sub-atmospheric pressure created by an engine on the outlet side of said throttle valve, a spring in said chamber acting to maintain said valve member closed, said spring exerting a predetermined force less than the suction force acting on said valve member at cold engine idling speeds whereby said responsive Valve member will be opened by suction upon firing of the engine to maintain cold engine operation, and manually operable means for controlling operation of said valve member.

18. A carburetor of the character described comprising a casing containing a mixing chamber having a mixture outlet passage, means to supply air to said chamber, means'to supply fuel to said chamber, a fuel reservoir, a throttle valve in said outlet passage, a fuel supply conduit leading from said reservoir to said mixture outlet passage beyond said throttle valve, a by-pass passage for by-passing fuel and air from said mixing chamber to said outlet when said throttle valve is closed, a valve for controlling said by-pass passage and responsive to suction on the outlet side of said throttle valve when the throttle valve is closed, said responsive valve closing said by-pass when the pressure in said outlet is substantially atmospheric pressure, yieldable means to hold said re sponsive valve in position to close said by-pass passage and exerting a predetermined resistance to movement of said responsive valve in a direction to open said by-pass passage whereby upon engine cranking a relatively rich fuel mixture will be supplied, the predetermined resistance being such that said responsive valve is in closed position at low engine cranking speeds and such that the resistance of said yieldable means is overcome at high engine cranking speeds which are less than cold engine idling speeds whereby the necessary volume of fuel mixture to provide for cold engine operation will be admitted past said throttle valve when closed upon firing of the engine, and valve means operable for controlling flow of fuel through said fuel supply conduit and for also controlling operation of said bypass valve.

19. A carburetor for supplying fuel mixture to an engine comprising a casing having a mixture passageway therethrough, means to supply air to said passageway, means to supply fuel to said passageway, a throttle valve controlling flow through said passageway and movable to a closed position wherein insufilcient fuel mixture will be discharged from said passageway to maintain cold engine idling operation, means to increase the quantity of fuel mixture supplied to the engine while said valve is maintained in said closed position, said additional fuel mixture being supplied from said fuel mixture passageway on the inlet side of said valve, means responsive to suction created by the engine for controlling said lastnamed means, and manually operable means for controlling said responsive means.

HENRY P. VAUGHAN.

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