US2325372A

US2325372A - Carburetor

Info

Publication number: US2325372A
Application number: US134070A
Authority: US
Inventors: Irven E Coffey
Original assignee: Carter Carburetor Corp
Current assignee: Carter Carburetor Corp
Priority date: 1937-03-31
Filing date: 1937-03-31
Publication date: 1943-07-27
Anticipated expiration: 1960-07-27
Also published as: BE510627A

Description

July 27, 1943.

Z II III! 'F/aZ I? WEN E 605 5 INVENTOR.

BY 08M 46 ATTORNEY.

I. E. COFFEY July 27, 1943.

CARBURETOR Filed March 51, 1937 8 Sheets-Sheet 5 [El 5N i. C y

. INVENTOR.

BY QM (A ATTORNEY.

July 27, 1943. I. E. COFFEY 2,325,372

CARBURETOR Filed March 31, 1937 8 Sheets-Sheet 4 fe J/EN E. (OFF/E, 4

INVENTOR.

ATTORNEY.

July 27 1943.

8 Sheets-g 5 Filed March 51, 1937 Q R a Willi/Ill ICS J VII 3 INVENTOR. BY [QM-M 46, M

RNEY,

July 27, 1943.

l. E. COFFEY 25325372 CARBURETOR Filed March 31, 1937 8 Sheets-Sheet 6 EVEN 5. Co /wax INVENTOR.

BY 4d.

ATTORNEY.

I. E. COFFEY July 27, 1943.

CARBURETOR Filed March 51, 1937 8 Sheets-Sheet 7 E F g 0 (N M N WI 1 I. E. COFFEY CARBURETOR July 27, 1943.

8 Sheets-Sheet 8 Filed March 31, 1937 W 5 r2 7. 2 M J].

' [E VEN 2 C-OPFEY.

INVENTOE,

5y HTTOEAAEY Patented J uly 27, 1943 CARBURETOR Irven E. Coifey, St. Louis, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application March 31, 1937, Serial No. 134,070

30 Claims. (Cl. 123-119) This invention relates to charge forming devices for internal combustion engines and consists particularly in novel means for automatically regulating the quality and quantity of mixture supplied to the engine cylinders particularly before the engine is heated to its normal running temperature.

In previous devices of this character the. use of a bi-metallic coil thermostat has been suggested but difiiculties have been encountered in getting the thermostat to heat up quickly enough after the motor starts so as to open the choke valve as soon as the engine is in a, warm enough condition to use a leaner mixture. Diiilculty has also been encountered in obtaining a suitable means to open the throttle valve or otherwise to supply sufiicient mixture to the engine to keep it running when the oil is cold and viscous. With the throttle in its normal closed position only sufficient air is admitted to the engine to produce power enough to turn it over at idling speed under normal temperature operating conditions, and if the throttle is moved to this position when the oil is cold and viscous, the engine does not have power enough to overcome the resistance of the oil and keep running. Inasmuch. as the throttle is normally held in closed posi' tion by a fairly stiff spring and since it is desired to reduce the bi-metallic coil thermostat to small proportions on account of expense, difliculty has been had in obtaining sufiicient power to automatically open the throttle when the engine cools off between periods of operation.

Another difiiculty that has been experienced with some previous installations results from the fact that the thermostat has been mounted on. the exhaust manifold or the hot spot of the intake manifold and connected to the choke valve of the carburetor by comparatively long linkage. Since the carburetor is not usually manufactured in the same factory where the engine is built, the assembly of these parts is not done by carburetor men but by general automobile mechanics and improper adjustment frequently re- 4 suits.

An object of the present invention is to provide means for automatically controlling the quality of mixture supplied to the engine during the starting and warm up period. 1

A more detailed object is to provide novel means for automatically controlling the carburetor choke and throttle valve during this period.

Another object is to provide thermostatic means for controlling the choke valve and means for controlling the temperature of the thermostat so that this member may control the choke valve accurately in accordance with the requirements of the engine.

Still another object is to provide means for positively opening the choke and throttle valves in case the manifold or cylinders should become excessively charged or loaded with fuel during the warm up.

These objects and other more detailed objects hereafter appearing are attained substantially by the structure illustrated in the accompanying drawings, in which:

Figure 1 is a side elevation of a carburetor constructed according to my invention, parts being broken away and others shown in sections.

Figure 2 is a sectional elevation of a carburetor constructed according to my invention, the view being taken from the side oppositeto that shown in Figure 1, and parts being broken. away and others shown in sections.

Figure 3 is a detail sectional view taken along the line 3-3 of Figure 2 looking in the direction of the arrows.

Figure 4 is a detail sectional view taken along the line 4-4 of Figure 1, looking in the direction of the arrows.

Figure 5 is a top view of the device.

Figure 6 is a detail view taken along the line 6-6 of Figure 3, looking in the direction of the arrows. I

Figure 7 is a slightly modified sectional view taken on line I-l of Figure 3.

Figure 8 is a view of a carburetor showing modifications,

Figures 9 and 10 are detailed sectional views of the same and showing operative parts in different positions.

Figures 11, 12, and 13 are elevational views showing operative parts of still another form, parts being in different positions.

Figure 14 is a side view of a carburetor embodying another modification.

Figures 15,16, and 17 are views of the form in Figure 14 but showing certain operative parts 5 only in different positions.

Figures 18 and 19 are perspective views of operative details.

Figure 20 shows a modified form of choke control.

The reference numeral l indicates the main body member of a carburetor mounted by means of a flange 2 on the intake manifold 3 of an internal combustion engine. The exhaust manifold is shown at 4. The carburetor comprises the usual throttle valve 5 controlled by a manually the main jet in accordance with the throttle position. The main nozzle l discharges at the throat of the venturi l3, which, in the present instance discharges into other and larger venturis to form a multi-stage mixing arrangement. This construction is already well known in the art, and

- no further description is necessary.

A diaphragm l4 subjected to the suction in the intake manifold of the engine by means of the conduit I5, is mounted on the body of the carburetor by means of the bracket l6 and connected to rocker arm II by means of the rod l8. A spri I9 is provided for moving the diaphragm to the right with respect to Figure 1 and this spring has suflicient strength to open the throttle valve by the means hereafter to be described, but the spring is still weak enough to be overcome by a suction in the intake manifold amounting to 6 or 7 pounds per square inch so as to permit the throttle to move to fully closed position.

The rocker arm I1 is fixedly mounted on the rock shaft which is also provided with the lever 2| fixed thereto. The lever 2| is provided with a transversely bentportion 22 at its end to insure contact with the lever 23 which is mounted on the throttle shaft 24. When there is no suction in the intake manifold, spring l9 pushes diaphragm l4 to the right as in Figure 1, and rotates shaft 20 in a clockwise direction thereby causing the transverse portion 22 to contact with and move the lever 23 to slightly open the throttle as soon as the engine stops, andto hold it there until the engine is cranked again and begins to run under its own power. A second lever 25 is mounted on the throttle shaft to rotate therewith and is connected by means of link 26 with the accelerating pump lever 21 carried by a rock shaft 28. The link 26 is provided with an inwardly projecting pin 29 for a purpose hereafter to be described The choke valve 30 is eccentrically mounted on a shaft 3| which extends thru the wall of the air horn 32 and is provided at one end with an arm 33 having a slot 34 therein. A link 35 has a pin 36 loosely mounted in slot 34 and is connected by pin 35a to upstanding portion 31a of a rocker am 31 which is pivotallymounted on the pillow block 38 by means of the pin 39. Rocker arm 31 is provided with 9. lug 40 disposed to cooperate with a lug 4| carried by lever 21. When the choke valve is in the closed position as indicated in Figure 1, lug 4|! interferes with lug 4| 1 to prevent anti-clockwise movement of the lever 21 sufiiciently to fully close the throttle. This position of the mechanism corresponds to a slightly open or fast idle" position of the throttle valve and insures the supply of sumcient fuel mixture to the engine to keep it in operation at low temperatures.

Whenever the choke is moved to open position, the rocker arm 31 is moved in a clockwise direction with respect to Figure l and lug 40 is moved out of the path of lug 4| permitting the throttle valve to be returned to its normal idling position. Due to the provision of the slot 34, there is no interference between the

lugs

40 and 4| during full closing movement of the choke valve even if, for some reason, the throttle valve should be in fully closed position. In case of failure of the diaphragm H to movethe throttle valve to partially open position when the engine stops, the choke valve would be moved to fully closed position upon the subsequent cooling of the engine, and the throttle valve would remain in closed position until it should be operated manually. As soon as the throttle valve is operated manually to a sufficiently open position, the rocker arm 31 would drop down by gravity to the position indicated in Figure l, and the re-closing of the throttle would be prevented until the choke valve had been opened sufllciently to move the lug 40 out of the path of lug 4|.

The other end of the choke valve shaft 3| extends into a. housing 42 which is thoroughly lined with cork or other heat insulating material as indicated at 43. The casing is formed in two parts as indicated in Figure 3, the outer portion being cup-shaped and removable. A radial arm 44 is rigidly secured to the end of choke valve shaft 3| within housing 42 and at its outer end is connected to a disk-shaped piston 45 by means of the curved connecting rod 46 as indicated in Figure 2. Piston 45 operates in a chamber 41 formed in housing 42. Cylinder 41 is provided with grooves or by-passes 48 formed on its opposite fiat sides but not extending the full length of the cylinder. Piston 45 closes these by-passes when it is in the position shown in Figure 2 or at the opposite end of the chamber or, in other words, the by-passes are closed when the choke is either substantially fully closed or fully open. By-passes 48 are formed with an irregular contour so as to provide an uneven suction action on the piston 45 in accordance with its position in the chamber. In order to provide for variations in the circularity of the cylinder 41, piston 45 is pivoted to the connecting rod 46 as indicated In order to obtain heat for warming up the thermostat when the engine starts, a hot air stove 50, open to the atmosphere, is provided on the exhaust manifold 4 and hot air is drawn up from the stove directly thru the conduit 5| to the interior of housing 42. The moving force which draws the hot air thru the housing is the suction within the intake manifold which is conveyed by means of a conduit 53 to chamber 41 in such a manner that the suction existing in the intake manifold is transmitted to piston 45. Whenever the piston 45 has been moved in a clockwise direction with respect to Figure 2 far enough to uncover by-pass 48, a strong draught of hot air is drawn from conduit 5| thru housing 42 and by-pass 48, thus warming up the inside of the housing and the thermostat 54. Conduit 53 is provided with a valve screw 15 by which the suction may be regulated. Thermostat 54 is fixedly mounted on the removable portion of housing 42 which is held in place by means of a flexible bracket 56 pivoted to a support as at 51 so that it may be swung aside to permit complete removal of the thermostat and the outer portion of the housing. The thermostat may be rotatably adjusted by turning the housing to the right or left and will be held in adjusted position by friction created by the pressure of the flexible bracket 56 against the outer portion of the housing.

The outer end of the thermostatic coil is provided with a hook 54a (Fig. '7) which engages pin 59 projecting from lever 44. The thermostat is of the bi-metallic coil type and the metals are so arranged as to rotate the lever 44- and the choke valve in an anti-clockwise direction with respect to Figure 2 when the temperature is low; in other words the choke valve will be closed when the engine is cold.

Figure 7 also shows a small hole 41a in the other wall of chamber 41 at the closed end which functions as a suctionby-pass for independently one direction only. The reason for this form-of connection is to permit the thermostat to freely expand or unwind without obstruction by any other element when the temperature is high. Thus the thermostat will not be subjected to strain when the temperature is above a predotermined degree.

I have. found it highly desirable to provide a fluttering action for the choke valve during the cranking of the engine. In order to do so I provide a magnet 59 held in place by screw 60, the magnet having a regular horse-shoe shape or being slightly curved, as indicated in Figure 2. Lever 44 has a projecting portion 6| which serves as an armature for the magnet. Projection 6| is, of course, constructed of iron or other magnetic material and contacts with the poles of the magnet when the choke valve is moved to fully closed position. Magnet 59 is preferably not of great strength and does not ,afiect the choke valve until the armature and magnet are brought in substantial contact. At all other times thermostat 54 is the only means for resisting opening of the choke and tending to close the same, the effect of the thermostat being dependent on the temperature. It should also be noted that magnet 59 is not even strong enough to offer any substantial resistance to the opening of the choke valve. The purpose of the magnet is to obtain a fluttering action of the choke valve during the cranking period and the amount of force required to set up this fluttering action is almost negligible.

The reason a fluttering action is desirable is substantially as follows:

When the engine is being cranked with the choke valve closed, there is substantial suction in the mixing chamber of the carburetor resulting in the discharge of large quantities of fuel from the main nozzle H), but the rate of air flowing thru the mixing chamber 65 of the carburetor is practically nil, the only air being admitted with the choke valve in closed position being the leakage past said valve. This does not carry sufiicient vaporized fuel to the engine. In previous constructions a small amount of 'air for conveying the cranking charges has been supplied by means of a bleeder hole, or small check valve mounted within the choke valve or in some equivalent location. Such devices supply a small constant current moving at low speed and substantialportions of the fuel vapor carried by such currents are either condensed on the walls of the manifold or precipitated the moment they reach the cylinders. One of the objects of this invention is to secure the movement of the air current from the carburetor to the cylinders in a succession of comparatively rapid impulses instead of in a steady flow or stream, the impulsive movement apparently having a better vaporizing effect on the gasoline and being more efficient to retain the gasoline in vaporized condition. One reason for this improved result is the individual impulses move at a much higher velocity than uniformly .flowing air admitted thru a small orifice.

In operation, when the motor is not running, there is no suction in the intake manifold and spring 19 moves diaphragm l4 to the right to the position shown in Figure 1, causing the partial opening of the throttle valve so as to provide ample fuel mixture during the cranking period and during the first few revolutions when it runs under its own power. The throttle valve being moved to partly open position, raises link 26 and rotates pump lever 21 in a clockwise direction with respect to Figure 1, lifting lug 4| up beyond the end of the lug 40. The choke valve is moved to closed position by the thermostat and piston is moved by the same means to the position shown in Figure 2. As soon as the engine starts to run under its own power, suction transmitted thru conduit IE will move diaphragm l4 to the left with respect to Figure 1, overcoming the pressure of spring l9 and permitting the throttle valve to move toward closed position until the lug 4| contacts with the lug 40, thereby preventing the complete closing of the throttlc valve and leaving it in the fast idle position.

During the cranking period the choke valve is intermittently opened by the suction and closed again by the thermostat at a fairly rapid rate, the fluttering action being caused or accentuated by magnet 59. It will be understood that the magnet has somewhat the effect of a snap action device which prevents the choke valve remaining fixed in a position which would leave the armature 6| in close proximity to the poles of the magnet, but not in contact therewith. For

instance, if the armature BI is within %4 of an inch of the poles of the magnet, the combined strength of the thermostat and the magnet will generally be sufilcient to move the choke quickly to fully closed position. The action of the suction being elastic and the movement of the piston of the engine being slow during th cranking period, an appreciable length of time is required to build up sufiicient suction to overcome the combined action of the thermostat and magnet on armature 6|. When the suction is built up to such a point that it is strong enough to break the armature away from poles of the magnet it is also strong enough to carry the valve a substantial distance beyond that necessary to admit the air at the rate at which it is being drawn in by the cylinders. The suction in the carburetor and intake manifold is accordingly immediately reduced to. practically nothing and the choke valve swings back toward closed position under the influence of the thermostat, acquiring sufficient momentum in doing so to insure movement of armature 6| into contact with the poles of the magnet, and then the operation is repeated. -There is some suction in the intake manifold during the cranking period, and this contributes to a certain extent to the opening of the choke valve during the cranking period, but the effect is more or less minimized by the fact that the piston 45 does not fit tightly even in the position shown in Figure 2 and there is some leakage around it in the cylinder 41.

As soon as the engine begins to run under its own power, a substantial amount of suction is devalve to an extent depending on the temperature,

the speed at which the engine may be running, and the position of throttle valve 5. Movement of piston 45 in a direction to open the choke valve also opens the passageway thru by-pass 48 which permits hot air to be drawn up rapidly from the air stove 50. The air is not warmed during the first few seconds of the running of the engine, but since the stove is mounted on the exhaust pipe, it is only a short time until it becomes heated. The high suction in the intake manifold draws a strong draught from the stove 50 and the thermostat in insulated housing 42 is quickly heated sufficiently to move the choke valve to full open position.

In order to properly control the movements of the choke valve in response to the action of piston 45, the capacity of conduit 53 may be controlled in any suitable manner. This control may be accomplished by merely selecting a proper size for the tube 53 or by the insertion therein of a restricted orifice or an adjusting valv as shown at 15 or any other suitable means. A similar adjustment could also be made for the conduit 5!.

As the choke valve approaches full open position, piston 45 moves to a position to restrict the flow of hot air thru cylinder 41, and restricts further heating of the thermostat. During continued operation of the engine, the leakage past the piston 45 is sufficient to keep the thermostat 54 hot so as to maintain the choke valve in fully open position. It is not necessary, however, to exceed temperatures of approximately 200 degrees Fahrenheit in housing 54 so that comparatively inexpensive thermostatic metal may be used.

Once the thermostat has been moved to fully open position insulation 43 on the housing prevents the too rapid cooling of the thermostat and avoids the supply of an over-rich mixture to a motor which has beenerecently operating and has not yet cooled down to a point where such rich mixture is required.

In case the engine does not start during the initial cranking it may become over-loaded and in such case it is desirable to provide manual means for opening the choke valve when clearing out the engine. For this purpose, there is provided the pin 29 which contacts with the lower part of the arm 31 when the throttle valve is moved to substantially fully open position'rotating arm 31 in clockwise direction with respect to Figure 1 and opening the choke valve. Thus the operator can open the choke valve by simply holding the throttle open so that with a few seconds further cranking the cylinders can be relieved of the excess gasoline.

The irregular contour of by-pass 48 is provided thermostat (not shown).

in order that the mixture ratio of air and gasoline,

as affected by the choke during the warm up, may be definitely controlled for any particular engine by changing the contour thereof. As piston moves in a clockwise direction with reference to Figure 2, the pull of the suction upon the piston is varied according to the particular contour of the by-pass, thereby causing the choke valve 30 to be opened a predetermined distance for any particular suction in the intake manifold. This action is provided in order that there may be greater economy and more efficient operation.

Figures 8, 9, and 10 show a modification in which suction chamber 41a is formed cylindrically instead of being longitudinally curved as in the previous form. This cylinder communicates with the interior of the mixture conduit posterior to throttle valve 5 by means of a suction connection 53a extending through the wall of the carburetor barrel. Cylinder 410 has a pair of grooves 48a in the wall thereof through which suction is communicated to the interior of housing 42 for the Heat is conducted to the interior of the thermostat housing from a stove 50 secured to a part 4 of the engine, conveniently, the exhaust manifold, through tubing 51a and screen 5. As in the previous form, a portion of the suction transmitted to chamber or cylinder 41a is by-passed around piston 45a, by means of grooves 48a, and functions to draw heated air from the stove past the thermostat. Grooves 480. may be tapered or otherwise varied, if desired, for varying the effect thereof according to the position of the piston 45a. When the piston is drawn to the bottom of its chamber, the size of the by-pass, and consequently the rate the heated air is drawn through the thermostat housing, is limited by the small groove 62 in the bottom of the piston.

Rotata-bly carried on a pivot 63 adjacent the throttle shaft is a cam-like member 64 having a weighted lobe 65 and projecting pin abutments 66 and 61. A link 68 is secured at its upper end to an arm 69 rigid with choke shaft 3| and at its lower end has a slot 10 receiving pin abutment 61. A crank 6a rigid with throttle valve 5 carries a screw H forming an adjustable abutment for cooperating with cam-like member 64 to limit closing movement of the throttle, as described hereafter, under certain conditions.

Figure 8 shows choke valve 30 held in a closed position by the thermostat, as for cold starting. Cam-like member 64 has been rotated by means of link 68 and pin abutment 61 so that a high point 12 thereof is engaged by throttle screw H to limit closing movement of the throttle valve to the fast idle" position. In starting the engine, the throttle valve may be opened somewhat farther than is shown in Figure 8, particularly in very cold weather. When the engine fires, piston 45a. will be drawn downwardly in chamber 410, due to the substantially increased suction applied thereto, thus positively opening the choke valve. The choke, :being unbalanced, will also be urged open by pressure applied directly thereto. Such opening movement of the choke valve causes link 68 to drop, permitting member 64 to rotate counterclockwise under the influence of weighted lobe 55, provided such movement is not resisted bythrottle screw H. But even though the cam-like member is held by the throttle screw, the choke valve is permitted substantially full opening movement independently of the interconnection due to the lost motion connection between link 58 and member 64, so that the choke may fluctuate back and forth during the warm up period in the manner of an air valve, th only resistance to such movement being offered by the thermostat.

In case of excessive loading of the intake manifold during the start or warm up, choke valve 30 may be substantially opened against the force of the thermostat. as in Figure 10. bv substantially full open movement of the throttle valve. This is effected by engagement between a projecting element 13 on the throttle crank and pin abutment 66 on the cam-like member, rotating this member counterclockwise so as to take up the lost motion between the same and link 68 and pull the link downwardly.

Figure 9'shows choke valve 38 moved to the full open position, as is the case after the thermostat has reached its normal operating temperature. Throttle crank 8a is shown, in solid lines, in the full open position with a projecting element l4 overlapping a lip 16 at the lower extremity of link 68 so as to lock the choke open. The lower portion of slot 18 is somewhat enlarged so that in case the throttle reaches its fully open position before the choke, the lip 13 can pass around projecting element 15 and drop thereunder by gravity. This figure also shows, in broken lines, the position of the throttle crank at normal idle with th abutment screw 1| adjacent a low point 12a on the cam-like member whereby full closing of the throttle is permitted.

Between the fast idle position of the parts, shown in Figure 8, and the normal idle position shown in broken lines in Figure 9, when the choke valve is partially open, cam-like member 84 will be in such position that teeth-like projections 11 will be engaged by throttle screw II to provide a variable fast idle. By means of this construction, the throttle may gradually ap proach closer to its full closed or normal idle position as the choke valve opens in order that the engine idling speed may be progressively decreased as the choke is opened.

Features of this form of the invention are described and claimed in substantially more detail in a copending application, Serial No. 83,066, filed June 2, 1936, in the names of August H. Blattner et a1.

Figures 11, 12, and 13 are views showing certain operative parts of another modification in various positions. Various carburetor parts, not shown, may be identical with the corresponding parts in previous figures. In this form, choke valve 30 is pivotally mounted in the carburetor air horn on shaft 3| which has at one end a small disk 18 and rotatably carries a weighted cam-like member I9 just inside of this disk, Also pivoted at 88 adjacent the choke shaft is a lever 8| carrying an abutment screw 82 and a projecting pin 83. A link 84 is secured at its lower end to throttle shaft 6b and at its upper end as a slot 8 receiving pin 83. A spring 86 yieldingly urges link 84 in a counterclockwise direction relative to its pivotal connection 81 with the throttle crank and a spring 88 hooked at one end on stop 89 constantly urges lever 8| in a clockwise direction. I

Figure 11 shows choke valve 30 held closed by the thermostat, as for cold starting. Disk 18 has an axial projection 98 on the circumference thereof which cooperates with a shoulder 9I on cam-dike member 19 to rotate this member clockwise when the choke is closed, lifting the weighted lobe 92 thereof so as to move a high point 93 in position to be engaged by abutment screw 82 to limit closing movement of the throttle valve to the fast idle position. Figure 12 shows the unloading position of the parts with the throttle fully opened and a radial projection 94 on disk 18 engaged by a lip 95 at the upper extremity of link 84 so as to rotate the disk and choke 38 in the counterclockwise or opening direction.

In Figure 13, choke 38 has been moved to its full open position and lip 95 engages a second radial projection 96 on disk I8 to lock the choke open. .Slot in link 84 has an enlarged lower portion which permits lip to pass around projection 9b, interlocking engagement between these parts being enforced by spring 86. In this position of the choke valve, cam-lik member I9 is permitted to rotate due to the weight of lobe 92 so as to move a low point 91 opposite abutment screw 82, permitting the throttle valve to fully close to the normal idle position. In this position of the throttle, a screw 98 carried by throttle crank 85 engages a stop 99 on the carburetor barrel. In this form, as in the previous form, the choke valve may be opened fully independently of the interconnection mechanism, with the cam-like member held in a fast idle position by screw 82. Features of this form are described and claimed in greater detail in a copending application, Serial No. 89,088, filed July 6, 1936, in the name of August H. Blattner.

In the modification in Figs. 14-48, the choke and throttle valve interconnection is effected through the intermediary of the accelerating pump mechanism, as in the first form. As shown in Fig. 14, crank 60, rigid with the throttle valve shaft is connected by means of link 280 with one end of an offset lever 21c, pivoted at 28, adjacent air horn 32, on a post or pillow block projecting above the bowl cover and shown in part I88. The other end of lever 210 is connected by means of a link I8I to the operating rod I82 on accelerating pump piston I83, the rod extending through the cover of bowl 8. Pivoted to lever 210 at I84 is the loose member generally indicated at I05 having its free end movable to a position adjacent link I8I. Member I85 has an inwardly extending lip I86 for cooperation with an angular arm 33c, rigid with choke shaft 3I and also has an outwardly and upwardly extending finger I01 extending beneath the pump lever.

The operation of this modification is substantially as follows: In Figs. 14 and 18, choke valve 38 is held closed by the thermostat, as during cold starting, and lip I86 on the loose member is supported by choke arm 330. A cam-like projection I88, at the free end of member I 85 extends between the bent over ends I89 and H8 of link I8I and a high point III thereon (Fig. 19) cooperates with roller II 2 on link part II8. In this position of the parts, loose member I85 forms a toggle with piston rod I82 to prevent further elevation of piston I83 and limit the closing movement of the throttle valve to the fast idle position, shown substantially exaggerated in Fig. 14.

In Fig. 15 the choke valve has started to open, as after the thermostat has partly warmed, causing choke arm 33a to rotate counterclockwise and permitting slight dropping of the free end of loose member I85 when released by depression of the pump piston, in turn, caused by the opening of the throttle valve. In this position of the parts, a relatively low point II3 on cam-like projection I88 cooperates with roller II2 to limit lifting of the pump piston and closing of the throttle. Point H3 is located somewhat closer to pivot I84 than is point III and, therefore, cooperation of this point with roller II2 permits the choke valve to approach closer to the fully closed position than is shown in Fig. 14, or, in other words, to an interme iate fast idle position.

Increased opening of th choke valve permits loose member I85 to rotate further in a clockwise direction under the influence of its own weight, bringing other points on cam-like projection I08 into position to cooperate with roller II2. Finally, when the choke is substantially fully opened, projection I08 drops away from the path of roller II2 so as to no longer restrict the upward movement thereof, permitting the throttle to fully close to the normal idle position shown in Fig. 1'1.

Fig. 16 shows the unloading position of the parts in which the throttle valve has been substantially fully opened, rotating pump lever 21c clockwise sumciently to engage curved finger I01 on loose member I05 and cause lip I06 to positively rotate choke arm 330 in a counterclockwise direction for opening the choke. In unloading, the upper edge of projection I08 also engages portion I09 of the pump piston link, but this is not essential. If desired, finger I01 may be omitted and engagement of the piston link element I09 and the cam-like projection relied upon in unloading.

In this modification, the choke and throttle valve interconnection is ineffective with the choke fully opened, as in Fig. 1'7, so that free movement of the throttle is permitted within its full range. With the choke closed, as in Fig. 14, the throttle is permitted substantial opening movement without positively afiecting the choke in the manner shown in Fig. 16. With the parts in the fast idle position, the choke may open fully against the thermostat without interference by the interconnection.

Fig. 20 shows a modified form of choke control including a rectangular housing IIO mounted on carburetor barrel I I I. The shaft of choke valve I I2 extends into housing III! as at H3, and carries therein a disc Il4 having an eccentric projection II5. Bi-metal coil H6 is secured at its inner end to a pintle III rigid with the housing wall and at its outer end extends downwardly into engagement with projection H5. A cylinder H8 carried by housing H has a threaded outer end for coupling with a suction connection, as 53 in Fig.2, and slidably receives piston H9 connected to disc II by link or rod I20. An aperture boss I2I provides for coupling a heat connection, as tube I in Fig. 2 with the housing.

As in case of the first forms described, thermostat IIG, when cool, yieldingly maintains the choke valve closed, as shown, for starting. When the engine fires, piston H9 is drawn to the right partially opening the choke against the thermostatic resistance. A hole I22 in piston II9 provides for slight leakage of suction for drawing heated gases through coupling I2I into the housing, and when the thermostat has become heated, it winds upon itself releasing the tension of the choke.' The relationship between choke shaft H3 and projection H5 and connecting rod pin I23 provides for varying the reactive effect between the unbalanced choke valve and the ther- I mostat and suction piston.

The invention is not limited to the structure shown, but may be modified in various respects as will occur to those skilled in the art, and the exclusive use of all such modifications as come within the scope of the appended claims is contemplated.

of applicant's application, Serial No. 117,822, filed December 28, 1936, for Improvements in carburetors.

I claim:

1. In a carburetor, a choke valve, means for opening said choke valve when the temperature is high and for closing said valve when the temperature is low, and means including a suction responsive element for setting up a fluttering action or the choke valve when the motor is being cranked with the choke valve in closed position.

2. In a carburetor, a choke valve, a heat responsive device for controlling said choke valve, and means including a suction responsive element. for setting up a fluttering action of said choke valve when the motor is cranked with the choke valve in closed position.

3. In combination with an internal combustion engine, a carburetor having a throttle and a pressure responsive choke valve, temperature responsive means for yieldingly urging the valve toward closed position and rendered inoperative at high temperatures, and means responsive to suction posterior to said throttle for moving the valve toward open position against the force of said temperature responsive means, said lastnamed means permitting full opening movement of said choke valve.

4. In combination with an internal combustion engine, a carburetor having a choke valve, temperature responsive means yieldingly urging the valve toward closed position, and suction operated means capable of moving the valve to at least a partially opened position against the force of the temperature responsive means, said choke valve being moved to fully open position when the normal operating temperature is reached or exceeded and remaining in such fully open position as long as said normal operating temperature is maintained or exceeded regardless of suction.

5. In combination with an internal combustion engine, a carburetor having a throttle and a pressure responsive choke valve, temperature responsive means for yieldingly urging the valve toward closed position and rendered inoperative for this purpose at high temperature, and means including a suction piston responsive to suction posterior to said throttle for moving the valve toward open position against the force of said temperature responsive means, said means being ineffective to resist lull opening movement of said choke valve, when the temperature is high.

6. In a carburetor having an induction passage, a choke valve movable into a position across said passage to substantially close the same and also movable into a position extending axially of said passage to constitute a minimum restriction therein, thermostatic means for urging said valve toward closed position, and manifold vacuum operated means separate from said induction passage for forcing said valve to at least partially open position.

7. In a carburetor having an induction passage, a choke valve movable from fully closed to fully open positions in said passage, means for controlling said valve during the starting and warm up period including a vacuum motor and a suction connection therefor, and heat responsive means for limiting the movement 01 said vacuum motor.

8. In a carburetor, a choke valve having a pivotal shaft, a throttle valve, a loosely pivoted stop member constantly urged towards a rest position,

structure including an element adjacent said stop member and movable with said throttle valve, and means for moving said stop member from said rest position to a fast idle position when said choke valveis closed, said element being disposed to cooperate with said stop member when in said fast idleqaosition to prevent full closing of said throttle valve, and said choke valve being movable to its full open position irrespective of said member and said element.

9. A carburetor as specified in claim 8 further including a body member having a boss forming a bearing for one end of said choke valve shaft and said stop member.

10. A carburetor as specified in claim 8 in which said stop member is actuated by gravity towards its rest position in which full closing of the throttle is permitted.

11. A carburetor as specified in claim 8 further including thermostatic means for closing said choke valve when the temperature is low and means on said throttle structure and said choke valve for at least partially opening said choke valve when said throttle valve is substantially fully opened.

12. A carburetor as specified in claim 8 in which said pivoted stop member includes a plurality of points at different distances from the pivotal support thereof for cooperating with said throttle elementto vary the fast idle position of said throttle valve in accordance with the position of said choke valve.

13. In a carburetor, choke and throttle valves, a member movable with said choke valve and a part movable with aid throttle valve, thermostatic means for operating said choke valve, and interconnection structure between said member and said part including a stop member pivotally supported adjacent said throttle part and a link extending between said members and having a lost motion connection with at least one of the same, said throttle part having an abutment disposed to cooperate with said stopmember to limit closing movement of said throttle valve.

14. In a carburetor, a mixture conduit, a choke valve, control means for said valve including thermostatic and suction responsive devices, a source of heated gases having an outlet adjacent said thermostatic device, a suction connection between said conduit and said suction responsive device, and a suction connection between said outlet and said suction connection for drawing heated gases from said source past said thermostat.

15. Structure as specified in claim 14 in which the suction connection for said heated gases constitutes a branch of the suction connection for said suction responsive device.

16. In a carburetor, a mixture conduit, a choke valve therein, a housing, control means for said valve including a thermostat in said housing, a suction chamber in said housing and communicating with said conduit, a source of heated gases connected to said housing and a piston in chamber and connected to said choke valve, there being a recess through the wall of said chamber inwardly of the portion thereof traversed by said piston and constituting a suction by-pass tor drawing heated gases through said housing.

17. In combination with an internal combustion engine, a carburetor having a throttle and a pressure responsive choke valve, temperature responsive means for yieldingly urging the valve toward closed position and rendered inoperative at high temperatures, and means responsive to suction posterior to said throttle for moving the valve to a partially opened position against the force of said temperature responsive means, said choke valve being movable to its full open position irrespective of said suction responsive means.

18. In combination with an internal combustion engine, a carburetor having a throttle and a pressure responsive choke valve, temperature responsive means yieldingly urgin the valve toward closed position and rendered inoperative at high temperatures, and means responsive to suction posterior to the throttle for moving the valve to a partially opened position against the force of the temperature responsive means, said choke valve being moved to fully open position when the normal operating temperature is reached or exceeded and remaining in such fully open position as long as said normal operating temperature is maintained or exceeded regardless of suction.

19. In a carburetor, means forming a mixing conduit, a choke valve for controlling the admission of air to said conduit, a heat responsive device connected to the operating shaft of said choke valve, a suction responsive device connected to the operating shaft of said choke valve and operated by the suction existing in the outlet of said mixing conduit, one of said devices being free to move in one direction only with respect to said shaft, and the other of said devices being rigidly connected to said shaft.

20. In combination with an internal combustion engine, a carburetor having a choke valve, temperature responsive means yieldingly urging the choke valve toward closed position, and suction operated means capable of moving the valve to a partially openedposition against the force of the temperature responsive means, said choke valve being moved to fully open position when the normal operating temperature is reached or exceeded and remaining in such fully open position as long as said norma1 operating temperature is maintained or exceeded, regardless of suction.

21. In a device of the class described, means forming a mixing conduit, a throttle valve and a choke valve for said mixing conduit, heat responsive means for closing said choke valve, said choke valve being mounted on an unbalanced shalt whereby it may be biased toward open position by the direct action of suction thereon, the amount of said suction applied to the choke valve being controlled by said throttle valve, additional suction responsive means for biasing said choke valve toward open position in response to increases of suction posterior to said throttle and mechanical means for biasing said choke valve toward open position when said throttle is moved to fully open position, whereby the movement of said choke valve to at least partially open position is insured whenever the engine is running with said throttle valve in fully open or substantially closed position.

22. In a device of the class described, means forming a mixing conduit, a throttle valve and a choke valve for said mixing conduit, heat responsive means for closing said choke valve, said choke valve being mounted on an unbalanced shaft whereby it may be biased toward open position by the direct action of suction thereon, the amount of said suction applied to the choke valve being controlled by said throttle valve, additional suction responsive means for biasing said choke valve toward open position in response to increases of suction posterior to said throttle, mechanical means for biasing said choke valve to ward open position when said throttle is moved to fully open position, whereby the movement of said choke valve to at least partially open position is insured whenever the engine is running with said throttle in fully open or substantially closed position, a control member, a suction operated diaphragm connected to said control member, and a one-way connection between said suction operated diaphragm and said throttle valve.

23. In an internal combustion engine, means forming a mixing conduit, a throttle valve in said conduit, a choke valve in said conduit, said choke valve being responsive to the direct action of suction, spring means biasing said throttle valve toward open position, suction operated means for overcoming said spring means and thereby relieving the throttle valve of the said biasing action, means for limiting the action of said spring means whereby said throttle is clear of interference by said spring means after the throttle has been moved to a predetermined partially open position, means forming a connection between the throttle and the choke valves whereby said choke valve may be moved to at least a partly open position by movement of the throttle valve to fully open position, said interconnection between the throttle and choke valve being constructed and arranged to cause opening movement of the choke valve only after said throttle valve has been opened to a position beyond the range of action of said spring means.

24. In an internal combustion engine, means forming a mixing conduit, a throttle valve in said conduit, a choke valve in said conduit, said choke valve being responsive to the direct action of suction, spring means biasing said throttle valve toward open position, suction operated means for overcoming said spring means and thereby relieving the throttle valve of the said biasing action, means for limiting the action of said spring means whereby said throttle is clear of interference by said spring means after the throttle has been moved to a predetermined partially open position, means forming a. connection between the throttle and the choke valves whereby said choke valve may be moved to at least a partly open position by movement of the throttle valve to fully open position, said interconnection between the throttle and choke valve being constructed and arranged to cause opening movement of the choke valve only after said throttle valve has been opened to a position beyond the range of action of said spring means, and means responsive to suction posterior to the throttle for assisting the movement of the choke valve toward open position.

25. In an internal combustion engine, means forming a mixing conduit,-a throttle valve in said conduit, a choke valve in said conduit, said choke valve being responsive to the direct action of suction, spring means biasing said throttle valve toward open position, suction operated means for overcoming said spring means and thereby relieving the throttle valve of the said biasing action, means for limitin the action of said spring means whereby said throttle is clear of interference by said spring means after the throttle has been moved to a predetermined partially open position, means forming a connection between the throttle and the choke valves whereby said choke valve ma be moved to at least a partly open position by movement of the throttle valve to fully open position, said interconnection between the throttle andchoke valve being constructed and arranged to cause opening movement the choke valve only after said throttle valve has been opened to a. position beyond the range of action of said spring means, and means responsive to suction posterior to the throttle for assisting the movement of the choke valve toward open position, and heat responsive means for further controlling the action of said choke valve.

26. In an internal combustion engine, means forming a mixing conduit, an unbalanced choke valve mounted in and controlling the admission of air to said mixin conduit, a manually operable throttle valve mounted in said conduit at a point posterior to said choke valve, means including a heat responsive device for yieldably closing said choke valve when the temperature is low, said choke valve being responsive to the direct action of air flow when the engine is running at low temperatures, and being constructed and arranged to be partially opened thereby to a position dependent on the temperature and the rate of air flow, and the rate of said air flow being controllable by said throttle, suction operated means operable in response to suction posterior to said throttle for assisting the opening of said choke valve by said air flow, said suction operating means being more effective to assist the opening of said choke valve when said throttle approaches closed position, whereby the maintenance of said choke valve in at least a partially open position is ensured under conditions when the direct effect of air flow on the choke valve is substantially cut off by the throttle, said suction responsive device being substantially inefiective to assist in openin said choke valve when said throttle is in wide open position, and mean operated by the movement of said throttle to wide open position to assist the direct action of the air flow in opening said choke valve at least to a partially open position.

27. In an internal combustion engine, means forming a mixing conduit, an unbalanced choke valve mounted in and controlling the admission of air to said mixing conduit, a manually operable throttle valve mounted in said conduit at a point posterior to said choke valve, means including a heat responsive device for yieldably closing said choke valve when the temperature is low, said choke valve being responsive to the direct action of air flow when the engine is running at low temperatures, and being constructed and arranged to be partially opened thereby to a position dependent on the temperature and the rate of air flow, and the rate of said air flow being controllable by said throttle, suction operated means operable in response to suction posterior to said throttle for assisting the opening of said choke valve by said air flow, said suction operating means being more effective to assist the opening of said choke valve when said throttle approaches closed position, whereby the maintenance of said choke valve in at least a partially open position is ensured under conditions when the direct efiect of air flow on the choke valve is substantially cut off by the throttle, said suction responsive device being substantially inefiective to assist in opening said choke valve when said throttle is in wide open position, means operated by the movement of said throttle to wide open position to assist the direct action of the air flow in opening said choke valve at least to a partially open position, and a suction operated diaphragm connected for operation by suction posterior to said throttle, a control member operable by said diaphragm, and a one-way connection between said control member and said throttle.

28. In a device of the class described. means forming a mixing conduit, a throttle valve and a choke valve for said mixing conduit, heat responsive means for closing the choke valve, said choke valve being normally biased towards open position by the direct action of suction thereon, additional suction responsive means for biasing said choke valve towards open position in response to increase of suction posterior to the throttle, mechanical means for biasing said choke valve towards open position when said throttle i moved toward fully open position, a control member, a suction responsive member connected to the control member, and a connection between the suction operated control member and said throttle valve.

29. In a device of the class described, means forming a mixing conduit, a throttle valve and a choke valve for said mixing conduit, heat responsive means for closing the choke valve, said choke valve being mounted on an unbalanced shaft, whereby it may be biased towards open position by the direct action of suction thereon, additional suction resp nsive means for biasing said choke valve towards open position in response to increase of suction posterior to the throttle, mechanical mean for biasing said choke valve towards open position when said throttle is moved toward fully open position, a control member, a suction responsive member connected to the control member, and a one-way connection between the suction operated diaphragm and said throttle valve,

30. In a device of the class described, means forming a mixing conduit, a throttle valve and a choke valve for said mixing conduit, heat responsive means for closing the choke valve, said choke valve being normally biased towards open position by the direct action of suction thereon, additional suction responsive means for biasing said choke valve towards open position in response to increase of suction posterior to the throttle, and mechanical means for biasing said choke valve towards open position when said throttle is moved toward fully open position.

IRVEN E. COFFEY.