US2890032A - Automatic starting carburetor - Google Patents

Description

June 9, 1959 c, BROWN ETAL 2,890,032

AUTOMATIC STARTING CARBURETOR Filed April 18, 1956 3 Sheets-Sheet 1 -FIG.I.

INVENTOR.

- WENFOR BY ATTORNEY June 9, 1959 x M. c. BROWN ETAL 2,890,032

' AUTOMATIC STARTING CARBURETOR 'Fil ed-April 1a,- 1956 v 3 Sheets-Sheet 2 2/ I [43 /4/ Q i 13k 57 3'9 7 I i {k '13? ,FlG.3.

INVENTOR. MORRIS C.BROWN W ENFORD E. HIGHLEY WMMMM ATTORNEY June 9, 1959 Filed April 18, 1956 M. 0. BROWN 'ETAL AUTOMATIC STARTING CARBURETOR 3 Sheets-Sheet 3' INVHVTOR. MORRIS C. BROWN WENFORD E. HIGHLEY AT TORNEY United States Patent Ofitice 2,890,032 Patented June 9, 1959 2,890,032 AUTOMATIC STARTING CARBUREToR Pontiac, Mich and Wenford High- MorrisC. Brown, v M H M0., assignors, by,mesne assignments,

ley, I Normandy,

to ACE Industries, Inhorbiirhfd, New York, N.Y., a'

This invention relates to carburetors for internal e'or'nbus'ti'on engines, and more particularly to priming means for supplying priming fuel to such engines for starting purposes.

The invention, as hereinafter diselosed, involves an improvement upon the automatic choke mechanism of the carburetor shown in Coffey US. Patent 2,325,372 dated July 27, 1943. Theautoinatic choke mechanism in this patent basically -ck'am'pri'ses a choke valve, a thermostat Bi'a'sing the choke valve toward closea positipnmean's responsive to suction, in the intake manifold "of the engine for opening the choke valve against the has or the thermostat, and means for heating the thermostat frofri the engine exhaust to change the thermostatic bias. With the advent of recent carburetor developrnents, such asthe inultigst'a'ge carburetor or the type 6on1- rhonly referred to as a four-barrel carburetor, it has be- :come n cessar to use a relatively stiff and hence relatix'rly large thermostat to provide proper resistance to e'p-emn of the choke valve in thepart thro'tt-I'e range in order to obtain adequate priming for cold I Theprinoipal object of this invention is to em e substantial reductio'nfof the size of the thermostat required in an automatie choke mechanism of the class descnb-ed. This gs attained, according to thepresent invention, by providihg a prir'niiig 'fuei passage from a source of fuel to the mixture conduit of the carburetor, the new through this passage being controlled by a choke-operated valve such manner that the passage is open during a portion of the range of opening movement of the choke valve and is closed w en the choke is opened a predetermined With this priming fuel passage, jsufiicie'n't priming fuel is supplied to the mixture conduit even though section in the ant-ere conduit may be reduced betas-Se of opening of the choke valve against the biasjof the "thermostat. Hence it is not necessary 'th'at the thermostat be made so large and as to hold the choke verve strongly closed for starting, and is possible to use a smaller thermostat than Would otherwise be required. A further feature of one form of the tion is an arrangement such that the mor have it if is used to control the admission of fuel to the mixture condu it from the priming passage during stated portion of the range of opening movement of the choke valve to compensate for decrease in suction which results from the opening of the choke valve. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention aecordingl-y comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanyin drawings, in which several of 'tnstratel,

various possible embodiments of the invention are i1- 2 Fig. 1 is a plan view of a four-barrel carburetor embodying the invention, certain parts being omitted;

Fig. 2 is a View in elevation of one end of the carbutater (the lower end of Fig. 1), parts being broken away and shown in section;

Fig. 3 is a vertical transverse section taken on either of the lines 3-3 of Fig; 1;

Fig; 4 is a fragmentary view taken on line 4 4 of s- Fig. 5 is a view in elevation of the other end of the carburetor from that shown in Fig. 2;

Fig. 6 is a fragment of Fig". 2 illustrating a moved position of parts;

Fig; 7 is a fragmentary view similar to Fig. 6 illustratiiig a modification, showing parts in a position corresponding to that of Fig 2; and,

Fig. 8 is a View similar to Fig. 7 fiCafibll'.

correspondin reference characters indicate corresponding parts throughout the several views of the drawings. I

Referring to the drawings, the invention is illustrated in its application to a rnulti-barrel, 'fnnlt'i-s't'ag'e carburetor of the type commonly referred to as a four-barrel carburetor. Only "so much of the construction of the carburefor as is essential to an understanding of this invention will be d'eseribed herein. Reference may be "made to (larlson et 211. US. iat'e'n't 2,715,522, dated August 16, 955, fof example, for such further details as may be desired. In general, the carburetor 1 comprises a fuel bowl section 3 having a flange 5 by which it may be attached to the intake manifold of the engine on which the carburetor is used. Mounted on the fuel bowl section 3 is the usual air horn section 7. The fuel bowl section 3 is formed to provide two primary mixture conduits each designated 9 and two secondary mixture Conduits each designated 11. The air horn section 7 is provided with a partition 13 dividing it to form a primary mixture co'n- 'dllit inlet 15 and a secondary mixture conduit inlet 17.

A choke valve 19 is provided in the primary inlet 15 for controlling the admission of air through the air horn section 7 to the two primary mixture conduits 9. The choke valve is fixed on a choke shaft 21 which extends across the air horn section 7 from one end to the other above the primary mixture conduits. Each primixture conduit 9 has a main ventu'ri 23 and aprirnar-y venturi 25. As to each of the primary mixture conduits 9, a main fuel nozzle 27 opens into its primary venmri 25. It will be understood that the nozzles 27 are supplied with fuel from the fuel bowl of fuel bowl section 3 in a manner such as that shown, for example, in U.S. Patent 2,715,522.

' A throttle valve 29 is provided each mixture conduit 9 below the main venturi 23. The throttle valves for both conduits 9 of the four-barrel carburetor are fixed on a throttle shaft 31 which extends across both these conduits. Adjacent one edge of each throttle29 are 'the usual idle ports 33 and 35 which are supplied with fuel via a passage indicated at 37. The port 35 is controlled by an adjustable needle valve 39 in known manner.

Each secondary mixture conduit 11 has a main venturi '41 and a primary venturi 43. A fuel nozzle 45 opens showing another 'rnodiinto the primary veiituri '43. This is supplied with fuel valves for bothconduits 11 of the tour-barrel oaibuitor 3 are fixed on a shaft 49 which extends across both these conduits.

A choke mechanism housing is indicated at 51 (see Figs. 1 and 2). This contains a suction and temperature-responsive mechanism of the character shown in the Coffey U.S. Patent 2,325,372. This mechanism includes a thermostat 50 engaging a control arm indicated at 53a within the housing 51 and fixed to a rotatable shaft which also has fixed thereto an arm 53 outside the housing. The center of the thermostatic spring 50 is fixed with respect to the housing 51. The arm 53 is connected by means of a link 55 to an arm 57 fixed on one end of the choke shaft 21 projecting out of air horn section 7. Also illustrated is a conventional suction motor 53a responsive to intake manifold suction to hold open the choke valve slightly when the engine starts running. Fixed on the other end of the choke shaft 21 (at the other end of the air horn section 7) is an arm 59 (see Fig. Arm 59 is connected by means of a link 61 to a fast idle cam lever 63 pivoted on the outside of fuel bowl section 3 at 65.

Also pivoted at 65 is a latch 67. The lower edge of this latch is formed with a shoulder 69 adapted for engagement by a dog 71 fixed on the end of the secondary throttle shaft 49 shown in Fig. 5. The latch 67 is biased to rotate clockwise as viewed in Fig. 5 by a weight 73 at its right end. Its left end is formed with a finger 75 adapted for engagement by an arm 77 formed integrally with a lever 79 fixed on the end of the primary throttle shaft 31 shown in Fig. 5. At the end of the lever 79 is an inturned lug 81 adapted to engage the fast idle cam lever 63 when the primary throttles 29 are fully opened, so as partially to open the choke valve 19 for unloading purposes. The primary throttle shaft 31 also carries an actuating lever 83 provided with a hole 85 for connection of an actuating rod (not shown). A lug 87 on the lever 83 has an idle set screw 89 threaded therein for adjusting the closed position of the primary throttles 31. Lever 83 is connected by a link 91 to one end of a pivoted lever 93 adapted to operate the plunger 95 of an accelerating pump (not shown).

An arm 97 is fixed on the end of the primary throttle shaft 31 projecting out of the end of the fuel bow-l section 3 at which the housing 51 is located (see Fig. 2). An arm 99 is rotatable on the end of the secondary throttle shaft 49 shown in Fig. 2. A link 101 has one end pin-connected to arm 97 at 103 and its other end 105 received in a slot 107 in arm 99. This provides a lostmotion connection between arms 97 and 99. An edge portion of the arm 99, indicated at 109, is arranged in abutting relation with an inturned lug 111 on an arm 113 secured to the secondary throttle shaft 49. Arm 113 carries a weight 115 for biasing the secondary throttles 47 closed. The secondary throttlm are velocity operated, i.e., unbalanced to open against the closing bias of the weight 115 in response to suction in the secondary mixture conduits 11 posterior to the secondary throttles. A cam 117 on the arm 97 is engageable with a cam follower 119 on the arm 99.

The wall of the air horn section 7 of the carburetor illustrated in Figs. 1-6 is provided at the end where the choke mechanism housing 51 is located with a vertical rib 121 in the vertical plane of the choke shaft 21 and along the primary inlet side with a horizontal rib 123. The vertical rib 121 has a vertical passage 125 extending from its lower end to a cylindrical valve chamber 127 coaxial with the choke shaft 21. The choke shaft extends through this chamber 127 and the portion of the choke shaft within the chamber is formed as a valve member as indicated at 129'. An induction tube 131 extends down into the fuel bowl from the lower end of the passage 125 below the level of fuel in the fuel bowl. The upper end of the tube 131 has a restriction 133. The

horizontal rib 123 has a horizontal passage 135 extending from the valve chamber 127 at right angles to the choke shaft. It also has a horizontal passage 137 extending parallel to the choke shaft along the primary inlet side of the air horn section 7. Passage 137 has connections such as indicated at 139 to two chambers 141 which open into the primary inlet through ports 143. The ports 143 are preferably elongated in longitudinal direction with respect to the primary inlet 15 and their location in relation to the choke valve 19 is such that when the choke valve is fully closed, the edge of the choke valve is located adjacent the posterior (lower) ends of the ports 143 so that there is only a small opening (indicated at O in Fig. 3) from each chamber 141 to the primary inlet 15.

The valve member 129 is so formed and so phased in its position with respect to the choke valve 19 to provide for communication from passage to passage during a portion of the opening movement of the choke valve and to block passage 125 when the choke valve is opened beyond a predetermined limit short of full opening. For example, the valve member may be formed and phased to :block passage 125 when the choke valve is angled threequarters open.

Operation of the embodiment of the invention Figs. 1-6 is as follows:

Upon starting the engine, assuming that the thermostat 50 in housing 51 is cold and that choke valve 19 is hence fully closed, initial opening movement of the primary throttles 29 creates a suction in the primary inlet 15 posterior to the choke valve and will induce a flow of fuel for priming purposes from the fuel bowl through the tube 131 and passages 125, 135, 137 and 139 (valve 129 being open) to the chambers 141 and from chambers 141 through the small openings 0 between the edge of the fully closed choke valve and the lower ends of ports 143 to the primary inlet 15. If the choke valve should be drawn open by suction against the resistance of the choke thermostat 50 in housing 51, responsive to opening movement of the primary throttles 29, with consequent reduction of suction in the primary inlet 15, the ports 143 are opened wider to the inlet 15 posterior to the choke valve to maintain the flow of priming fuel despite the decrease in suction. When, after the engine has been started, the choke thermostat 50 in housing 51 is heated and moves the choke valve to its fully open position (see Coffey U.S. Patent 2,325,372 for full details of this operation), the valve member 129 blocks the passage 125 to cut off the flow of priming fuel. As above explained, cut-oif of flow of priming fuel occurs when the choke valve is opened, for example, to three-fourths of its range.

Since the fuel induction passage constituted by the tube 131 and passages 125, 135, 137 and 139 provides for induction of fuel from the fuel bowl to the mixture conduit even though the choke valve may open, it is apparent that the thermostat 50 in the housing 51 is relieved of the function of holding the choke valve strongly closed for cold starting. Hence a smaller thermostat may be used than would be required in a carburetor without such a passage.

The choke Valve 19, the primary throttles 29 and the secondary throttles 47 are shown closed in Figs. 2, 3 and 5. The secondary throttles 47 are locked against opening "by engagement of the dog 71 with the shoulder 69 of latch 67 (see Fig. 5). The arm 99 occupies a position between the lug 111 on arm 113 and the cam 117 on arm 97 (see Fig. 2). The end 105 of link 101 is located at the right end of the slot 107 in arm 99, as viewed in Fig. 2.

To open the primary throttles 29, the lever 83 is swung clockwise as viewed in Fig. 5 by the actuating rod (not shown). This rotates the primary throttle shaft 31, lever shown in ,79 and the primary thottles 29 clockwise as viewed in Fig. 5, and rotates the arm 97 counterclockwise as viewed in Fig. 2. The latch 67 remains in the Fig. 5 locking assess s pesition, holding the seet anc'lary threttl'es against open;

the arm 77 on lever 79 engages i stinger 75on the latch and rotates the latch eeuntereloekwise' as viewed in Fig. far enough for the dog 71 to escape from the shoulder69. V x v Upon the stated counterclockwise rotation of the arm 97 the m 117 011 isj fi sv o nw d Pa t follower 119 on arm 99, and the end 105 of 101 slides from the right end of the slot 107 in arm to the left end of the slot. The cam 117 clears the follower 119 somewhat prior to release of the latch 67. Upon further counterclockwise rotation of thearm 97 thelink 101 is dragged to the right, thereby freeing the arm 99 for clockwise rotation. This freesthe secondary throttles 47 for opening against the bias of weight 115 in response to suction. However, even if the secondary throttles do not open under suction, arm 97 may continue to rotate counterclockwise upon further opening of the primary throttles due to the lost motion of the end 105 of the link 101 in slot 107 and the capability of arm 99 to rotate relative to the secondary throttle shaft. Assuming that the secondary throttles do open, the. degree of opening is controlled by the primary throttles because of the engagemerit of the lug 111 on arm 113 with the edge portion 109 of arm 99, and the engagement of the left end of the slot 107 with the end 105 of link 101.

Upon return of the primary throttles to the closed position, lever 79 rotates counterclockwise and arm 97 rotates clockwise back to the positions shown in Figs. 5 and 2. Arm 97 acts through engagement of the 117 with the follower 119 on arm 99 and through the link 101 to rotate the arm 99 counterclockwise, andarm 99 acts through engagement of its edge portion 109 with lug 111 on arm 113 to return the secondary throttles to closed position. Upon such closure, the dog 71 reaches the position shown in Fig. 5, and the finger 75 on the latch 67 is released from the arm 77 on lever 79 so that the latch drops into locking position with respect to the dog 71, thereby locking the secondary throttles against opening.

When the choke valve is closed, the secondary throttles will normally be locked closed, but full opening ,movement of the primary throttles releases the latch 67, permitting the secondary throttles to open, and opens the choke valve simultaneously therewith.

The secondary throttle mechanisms are similar to' those shown in the copending coassigned applications of Harold A. Carlson and Olin J. Eickmann entitled Secondary Stage Throttle Control for Multi-Stage Carburetor, Serial No. 582,421, filed April 26, 1956, now Patent No. 2,836,404, dated May 27, 1958, and of Leland B. Read entitled Latching Secondary for Two stage Carburetor, Serial No'. 593,519, filed June 25, 1956, to Which reference may he made for further detail.

Fig. 7 shows a modification differing from the construction shown in Figs. 1-6 in that the fuel induction passage, instead of opening into the primary inlet, opens into the main venturi 23. In Fig. 7 the fuel induction passage is generally designated 151', and it is shown to be provided with a nozzle 153 projecting into the main venmii 23. Operation of the modification shown in Fig. 5 corresponds to that of the mndification shown in Figs. 1'4 except, of course, that the nozzle 153 is always fully open to the main venturi, and net under control 'of the choke valve 19, except as regards the valve portion 129 of the latter.

Big. 8 shows a modification difi erin g from the construction shown in Figs. 1-7 in that the fuel induction passage, generally designated 161, instead of opening into the primary inlet or the main venturi, opens into the priinary mixture conduit 9 posterior to the primary throttle 29: Operation of themodification shown in Fig. 8 cori es pbnds to that ofthe modification shown in Fig. 7 exc hfc 'ourse, that the passage 161 is subject to suction postericir of the prin'iary throttle.

In view; of the a'hove', it will be seen that the several ebjects of the invention are achieved and other advaniagebus results attained; Y

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained the above description or shown the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

1. In a carburetor having a mixture conduit and a there valve on a choke shaft for wntmuing the admission of air to the mixture conduit, resilient means resisting opening movement of said choke valve and being of a stren th to ermit said ch ke valve to open SliifiCifitiy during cranking of an associated engine to reduce the suction in said mixture conduit below that required for normal starting, means providinga fuel passage for flow of fuel from a source tothe mixture conduit, one end of said choke shaft being formed as a value and extending into a valve chamber formed in said fuel passage means, said last-named valve being formed for variably opening the passage during a portion of the range of opening movement of the choke valve and for blocking the passage when the choke valve is opened beyond a predetermined limit short of full opening, thereby permittin-g the use of a weaker resilient means. 2. In a carburetor having a fuel bowl, a mixture eonduit having an inlet, a choke valve in said inlet for controlling the flow of air into the mixture conduit respensive to opening and closing movement of said clinke valve, means providing a fuel induction passage from below the level of fuel in the bowl to a port in the inlet for induction of fuel from the bowl to the inlet, and said port being adjacent the upstream edge of said choke Valve when said choke valve is closed for variably controlling through said passage responsive to movement of said edge past said port.

3. In a carburetor having a fuel bowl, a mixture conduit having an inlet, and a suction responsive choke valve in said inlet on a choke shaft for controlling the admission of air to the mixture conduit, resilient means resistmg opening movement of said choke valve and being of a strength to permit said choke valve to open sufficiently during cranking of an associated engine to reduce the suction in said mixture conduit below that required for normal starting, means providing a fuel induction passage froin below the level of fuel in the bowl to the inlet for induction of fuel from the bowl to the inlet, one end of said choke shaft being formed as a valve and extendmg into a valve chamber formed in said induction passage means, said last-named valve being formed for opening the passage during a portion of the range of opening movement of the choke valve and for blocking thepassage when the choke valve is opened beyond a predetermined limit short of full opening, thereby permitting the use of a weaker resilient means.

4. In a carburetor having a mixture conduit provided with an inlet and a choke valve in said inlet for controlling the admission of an to the mixture conduit, resilient means resisting opening movement of said choke valve and being of a strength to permit said choke valve to open sufficiently during cranking of an associated eng ne to reduce the suction in said mixture conduit below that required for normal starting, means providing a fuel passage for flow of fuel from a source to the inlet, said passage openinginto the inlet through a port adjacent an edge of said choke valve, said choke valve traversing said port during opening movement of the choke valve to control the flow of fuel through said port.

5, In a carburetor having a mixture conduit provided with an inlet and a choke valve in said inlet for controlling the admission of air to the mixture conduit, means providing a fuel passage for flow of fuel from asource to the inlet, and a valve said passage movable with the choke valve, the latter valve being open during a portion of the range of opening movement of the choke providing a fuel passage for flow of fuel from a source to the inlet, one end of said choke shaft being formed as a valve and extending into a valve chamber formed in said passage means, said last-named valve being formed for opening the passage during a portion of the range of opening movement of the choke valve and for blocking the passage when the choke valve is opened beyond a predetermined limit short of full opening, said passage opening into the inlet through a port which is elongated in longitudinal direction with respect to the inlet and which is so located in respect to the choke valve that, when the choke valve is closed, an edge portion of the choke valve is located adjacent the posterior end of the port, and, as the choke valve opens, said port is opened wider to the inlet posterior to the choke valve.

7. In a carburetor having a fuel bowl, a mixture conduit having an inlet, and a choke valve in said inlet for controlling the admission of air to the mixture conduit, means providing a fuel induction passage from below the level of fuel in the bowl to the inlet for induction of fuel from the bowl to the inlet, and a valve in said induction passage movable with the choke valve, said induction passage valve being open during a portion of the range of opening movement of the choke valve and closing when the choke valve is opened beyond a predetermined limit short of full opening, said passage opening into the inlet through a port traversed by the choke valve as the choke valve opens.

8. In a carburetor having a fuel bowl, a mixture conduit having an inlet and a choke valve in said inlet on a choke shaft for controlling the admission of air to the mixture conduit, means providing a fuel induction passage from below the level of fuel in the bowl to the inlet for induction of fuel from the bowl to the inlet, one end of said choke shaft being formed as a valve and extending into a valve chamber formed in said induction passage means, said last-named valve being formed for opening the passage during a portion of the range of opening movement of the choke valve and for blocking the passage when the choke valve is opened beyond a predetermined limit short of full opening, said passage opening into the inlet through a port which is elongated in longitudinal direction with respect to the inlet and which is so located in respect to the choke valve that, when the choke valve is closed, an edge portion of the choke valve is located adjacent the posterior end of the port, and as the choke valve opens, said port is opened wider to the inlet posterior to the choke valve.

9. In a carburetor having a fuel bowl, a mixture conduit having a venturi, and a choke valve on a choke shaft for controlling the admission of air to the mixture conduit, resilient means resisting opening movement of said choke valve and being of a strength to permit said choke valve to open sufficiently during cranking of an associated engine to reduce the suction in said mixture conduit below that required for normal starting, means providing a fuel induction passage from below the level of fuel in the bowl to the venturi for induction of fuel from the bowl to the venturi, one end of said choke shaft being formed as a valve and extending into a valve chamber formed in said induction passage means, said last-named valve being formed for opening the passage during a portion of the range of opening movement of the choke valve and for blocking the passage when the choke valve is opened beyond a predetermined limit short of full opening, thereby permitting the use of a weaker resilient means.

10. In a carburetor having a fuel bowl, a mixture conduit, a throttle, and a choke valve for controlling the admission of air to the mixture conduit, resilient means resisting opening movement of said choke valve and being of a strength to permit said choke valve to open sufficiently during cranking of an associated engine to reduce the suction in said mixture conduit below that required for normal starting, means providing a fuel induction passage from below the level of fuel in the bowl to the mixture conduit posterior of the throttle for induction of fuel from the bowl to the mixture conduit, and means responsive to initial opening movement of the choke valve for controlling flow through said passage to permit a sufficient flow of fuel to said mixture conduit for starting, thereby allowing the use of a weaker resilient means.

11. In a carburetor having a fuel bowl, a mixture conduit, a throttle, and a choke valve for controlling the admission of air to the mixture conduit, resilient means resisting opening movement of said choke valve and being of a strength to permit said choke valve to open sufficiently during cranking of an associated engine to reduce the suction in said mixture conduit below that required for normal starting, means providing a fuel induction passage from below the level of fuel in the bowl to the mixture conduit posterior of the throttle for induction of fuel from the bowl to the mixture conduit, and a valve in said induction passage movable with the choke valve, said induction passage valve being open during a portion of the range of opening movement of the choke valve and closing when the choke valve is opened beyond a pre determined limit short of full opening to permit a suflicient flow of fuel to said mixture conduit for starting, thereby allowing the use of a weaker res lient means.

12. In a carburetor having a fuel bowl, a mixture conduit, a throttle, and a choke valve on a choke shaft for controlling the admission of air to the mixture conduit, resilient means resisting opening movement of said choke valve and being of a strength to permit said choke valve to open sufiiciently during cranking of an associated engine to reduce the suction in said mixture conduit below that required for normal starting, means providing a fuel induction passage from below the level of fuel in the bowl to the mixture conduit posterior of the throttle for induction of fuel from the bowl to the mixture conduit, one end of said choke shaft being formed as a valve and extending into a valve chamber formed in said induction passage means, said last-named valve being formed for opening the passage during a portion of the range of opening movement of the choke valve and for blocking the passage when the choke valve is opened beyond a predetermined limit short of full opening, thereby permitting the use of a weaker resilient means.

13. In a carburetor having a mixture conduit, a constant level fuel chamber, a throttle, a choke valve for controlling the admission of air to the mixture conduit, resilient means resisting opening movement of the choke valve, a main fuel system, an idle port and a supply passage therefor, an auxiliary fuel system including a fuel passage connecting the fuel chamber and the mixture conduit, and means responsive to initial opening movement of the choke valve for controlling the flow through said fuel passage to permit a sufficient flow of fuel to said mixture conduit for starting.

14. In a carburetor having a mixture conduit, a constant level fuel chamber, a throttle, a choke valve for controlling the admission of air to the mixture conduit, resilient means resisting opening movement of the choke valve, a main fuel system, an idle port and a supply passage therefor, an auxiliary fuel system including a fuel passage connecting the fuel chamber and the mixture conduit, and valve means responsive to a portion of the opening movement of the choke valve for opening said fuel passage to supply a priming mixture, said valve means blocking the 9 fuel passage when the choke valve is moved beyond a predetermined limit.

References Cited in the file of this patent UNITED STATES PATENTS 1,821,014 Heitger Sept. 1, 1931 10 Stokes Apr. 19, 1932 Firth May 31, 1932 Heitger Feb. 21, 1933 Kirby July 11, 1933 Leibing Apr. 6, 1943 Udale Nov. 11, 1952 Carlson et a1 Feb. 11, 1958

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