US2603198A

US2603198A - Automatic choke valve

Info

Publication number: US2603198A
Authority: US
Publication date: 1952-07-15
Anticipated expiration: 1969-07-15

Description

July 15, 1952 c. J. swlGERr AUTOMATIC CHOKE VALVE 2 SHEETS-SHEET 1 Original Filed Aug. 29, 1932 nventor ze/zce Mfg/waz Gttornegs July 15,. l952 c. J. swlGERT l. 2,603,198

AUTOMATIC CHOKE VALVE Original Filed Aug. 29, 1952 2 SHEETS-SHEET 2 gu I 9M /W Gttomegs Patented July 15, 1952 AUTOMATIC CHOKE VALVE Clarence J. Swigert, West Hartford, Conn., as-

signor, by mesne assignments, to General Motors Corporation, Detroit, Mich., a corporation of Delaware Original applicationAugust 29, 1932, Serial No.

630,805, now Patent No. 2,427,030, dated Septomber 9, 1947. Divided and this application August 30, 1947, Serial No. 771,498

(Cl. 123 l19) 15 mains. 1

To facilitate starting and to insure most eiilcient operation of an internal combustion engine under different conditions, there is commonly provided in the air intake passage to the carburetor of the engine a valve, commonly called a choke valve, which controls the ow of air through the passage and, consequently, the ratio vof fuel to air in the combustible mixture supplied by the carburetor to the cylinders of the engine. Many mechanisms, some of which regulated the position of the chokevalve in accordance with the temperature of the engine and others of which regulated the position.k of the chokevalve in accordance with the speed and load of the engine, have been suggested for automatically regulating the position of the choke valve of an internal combustionengine. However, since, as my eX- periments have shown, the ratio of fuel to air which is desirable in the combustible mixture supplied to the cylinders of .an internal combustion engine is a function both of the temperature and of the speed and'load of the engine,` none of v these mechanisms has entirely satisfactorily accomplished Ythe result that it was designed to accomplish.

This invention relates to mechanism for automatically regulatingthe position of the choke valve of the carburetorof an internal combustion engine and resides principally in such a mechanism whichV is so constructed and/or arranged that the position of the choke Vvalve is affected by both the temperature and the speed and load of the engine. This application is a division of my application, Serial No. 630,805, filed August 29, 1932, which has matured into Patent 2,427,030, dated September 9, 1947.

For a better understanding of vthe nature and objects of the present invention, reference is made to the following specification in which there are described the preferredembodiments of my invention which arellustrated in the accompanying drawing,

In the accompanying drawing:

Fig. l is a View of choke valve regulating mechanism in which my invention is embodied installed on an internal combustion engine.

Fig. 2 is a top plan view of the mechanism shown in Fig. l with the cover removed.

Fig. 3 is a section taken on the line 3 3 of Fig. 2.

Fig. 4 is a section taken on the line 4 4 of Fig. 3. y

Fig. 5 is a View of a second form of choke valve regulating mechanism in which my invention is embodied installed on an internal combustion engine with the parts in the positions which they occupy when the choke valve is nearly fully closed.

Fig. 6 is a section taken on the lines 6 5 of Figsand?. I

Fig. 6a is an enlarged exploded perspective view of parts of the mechanism shown in Figs. 5 andV 6. Fig. 7 is a fragmentary view taken as indicated by the line 1 1 of Fig. 6. f

Fig. 8 is a fragmentary section taken on the line 8 8 of Fig. 5. Y Fig. 9 is a View of a third form ofchoke Valve regulating mechanism -in which my invention is embodied installed onzan internal combustion engine. f 1 f f In Figs. 1 to 4 of the'vdrawing, there is shown part of the induction system of an internal combustion engine which includes a carburetor I9 into which air is drawnthrough the conduit II and from which combustible mixture is discharged through the conduit I2 anda manifold I3 through which the combustible mixture V'discharged from the conduit I2 is conducted tothe intake ports ofl the cylinders lof the engine.

Within the conduit I2 on the shaft Irl, there is mounted a throttle y'valve 52 of the butterfly type. and within the/conduit II'on the shaft I5, there is mounted a'choke valve I 5 of the butterfly type 4which is notableonly in this, that,.as 'shown in the drawing, the portion thereof which moves inwardly as the valve opens is of greater area than the portion on the opposite side of the shaft I5 and, consequently, that flow of air into the carburetor will tend to open it.

In the form shown in Figures 1 to 4, the mechanism in which my invention is embodied includes a body II which consists of a pair of spaced parallel walls I8 and I 9 mounted on and formed integrally with a base 20 Which is seated on and secured by means of screws, such as 2l, to the intake manifold I3. The open sides of the body Il are closed by a cover 22. j

To the outer side of the wall I8, there is secured an element 23 on which there is provided a sleevelike extension which projects through an opening in the wall into the interior ofthe body I'I. In the element 23, there is journalled a hollow shaft 24 which projects into the interior of the body, I'I' beyond the mentioned `extension of the element 23. Through the hollow shaft 24 and through the wall I9 of the body, there extends a shaft 25 which is journalled inthe hollow shaft and in the Wall I9. To the end of the shaft 25 which extends through the wall I9,lthere is fixed, without `the body I1, a crank arm v2Eiwhich is connected by a link 21 to an operating arm 28 which is fixed to the shaft on which the choke valve I6 is mounted. To the opposite end of the shaft 25, beyond the outer end of the hollow shaft 24, there is secured the inner end of a bimetal thermostatic coil spring 29 which is located within a cup-shaped housing 30 which is secured to the element 23 by the screws 3| which secure it to the wall I8. The outer end of the thermostatic spring 29 is secured to the outer end of an arm 46 whose inner end isl fixed to the outer end of the hollow shaft 24. In the walls I8 and I9 of the body, there are provided aligned openings through which extends and in which there is journalled a shaft 32 on one of whose ends, without the body, there is fixed a crank arm 33 which is connected, through a link 34, a bell crank 35 and a link 36, to an arm 31 which is fixed to the shaft on which the throttle valve 52 is mounted.

On one end of the base 20 and integral therewith, there is formed a hollow cylinder 38 whose outer end is closed by a head 39 and whose open inner end is located between the walls I8 and I 9. The interior of the cylinder communicates with the interior of the intake manifold I3 through a passage 49 which extends through the head 39, the base 20 and the upper wall of the intake manifold. Within the cylinder 3B, there is located a piston 4I which is urged away from the headV end of the cylinder and toward the abutment 5I which serves to limit its outward movement by a coil spring 42 and whose outer end is connected by a link 43 to the arm 44 of a bracket choke valve toward closed position and to rotate the hollow shaft 24 in such a direction (clockwise, as viewed in Figure 4) as to move the piston toward the head end of the cylinder and (3), when its temperature falls below a preselected minimum (e. g., '10 F. to 80 F.), it will, if unresisted, maintain the choke valve in fully closed position. From what has been said in the preceding sentence, it will be apparent that thc thermostatic spring 29, when its temperature is below the mentioned preselected minimum, tends to maintain the choke valve in fully closed position and, lwhen.` its temperature equals or exceeds the mentioned preselected minimum, tends to regulate the position of the choke valve in ac- Y cordance with its temperature and, consequently,

45 which is fixed to the portion of the hollow shaft 24 within the body.

On the shaft 32, Within the body I1, there is fixed to the shaft 32 a similar U-shaped element 59. To the shaft 25 between the inner end of the hollow shaft 24 andthe wall I9 of the body, there is fixed an arm 5I whose extremity overlies the juxtaposed arms of the elements 41 and 59.

While, as indicated in Figure 3, the choke valve regulating mechanism illustrated in Figures 1, 2, 3 and 4 of the drawing and hereinbefore described is designed to be installed on an engine with the thermostatic spring 29 located in such close juxtaposition to the exhaust manifold II1 thereof that it will be affected by the heat radiated therefrom, it will be understood that, if so desired, the mechanism may be so installed that the thermostatic spring will be affected by heat radiated from a part of the engine other than the exhaust manifold.

The thermostatic spring 29 is s0 constructed and arranged that (l), as its temperature rises, it tends to rotate the shaft 25 in such a direction (counter-clockwise, as viewed in Figure 1, or clockwise, as viewed in Figure 4) as to move the choke valve I6 toward open position and to rotate the hollow shaft 24 in s uch a direction (counter-clockwise, as viewed in Figure 4) as to move the piston 4I away from the head end of the cylinder 38, and (2), as its temperature falls, it tends to rotate the shaft 25 in such a direction (clockwise, as viewed in Figure l, or counterclockwise, as viewed in Figure 4) as to move the in accordance with the temperature of the exhaust manifold H1.

It will, however, be noted that, when the engine on which the mechanism shown in Figures 1, 2, 3 and 4 is installed is operating, two other forces, viz., the flow of air through the conduit II and the pressure within the intake manifold may affect the position ofthe choke valve IB and, consequently, that the position of the choke valve is a function of both the temperature and the speed and load of the engine. It is obvious that an increase in the rate of flow of air through the conduit I I will tend to move the choke valve toward its fully open position, through the shaft 25, coil up the thermostatic spring 29 and through it, the hollow shaft 24, the bracket 45 and the link 43 move the piston 4I toward the head end of the cylinder 38` and that a decrease in the rate of iiow. of air through the conduit II will tend to permit the thermostatic spring 29 to uncoil and the spring 42 to expand and move the piston away from the head end of the cylinder and the thermostatic spring and/or the spring, thus, 42 to move the choke valve toward its fully closed position. It is also apparent that a decrease in the pressure within the intake manifold of the engine will tend to move the piston 4I toward the head end of the cylinder 38 and, through the link 43, the bracket 45, the hollow shaft 24 and the arm 46 coil up the thermostatic spring 29 and move the choke valve toward its fully open position and that an increase in the pressure Within the intake manifold will tend to permit the spring 42 to move the piston 4I away from the head end of the cylinder and, through the mentioned elements, uncoil the thermostatic spring and move the choke valve toward its fully closed position.

As shown in Figure 1, when the choke valve I 6 is in its fully closed position, the center of the pivotal connection between the arm 26 and the link 21 is located slightly to the side of the line joining the axis of the shaft 25 and the center of the pivotal connection between the link 21 and the arm 28 opposite that on which it is located when the choke valve is in its fully or partially open position. Consequently, when the choke valve is in its fully closed position, flow of air through the conduit l I will be ineffective to move the choke Valve toward its fully open position and, if the engine be started with the choke valve in this position, it will continue to operate with the choke valve in its fully closed position until the temperature of the thermostatic spring 29 has increased and/or the pressure in the intake manifold has decreased to such an extent that the tendency of either or both of these forces to rotate the shaft 25 in such a direction as to open the choke valve becomes sufficient to move the center of the pivotal connection between the arm 26 and the link 2l over center, after which the iiow of air through the conduit il will'become a factor in determining thelpositicn of the choke valve. The feature of the mechanism described in this paragraph is important because it insures that if the 'engine on which the mechanism is installed is started when its temperature is lower than the mentioned preselected minimum, it will, for a suiciently lengthy period to avoid a false start, be supplied with the very rich combustible mixture whichV is essential to quick and easy starting of the'engine under these conditions.

In connection with the mechanism'shown in. Figures 1, 2, 3 and 4:, it will be. noted that when the choke valve is in its fully closed position, the pin Q9 on the arm t8 of the bracket i5 isin engagement with one arm of the element 41 and that the other arm of the element Mis in'engagement with the arm 5i and, consequently, that rotation of the hollow shaft 2t in response te a decrease in the pressure within the intake manifold will be transmitted to the shaft positively instead of through lthe thermostatic spring 29, and, therefore, that the considerable force which must be applied to the shaft 25 as a result of a decrease in pressure Within the intake manifold t0 move the center of the pivotal connection between the arm 26 and the link 2l over center will not beimposed upon the thermostatic spring. In connection with this mechanism, it will also be noted that when the throttle valve 52 is moved toward its open position, the shaft 32 will be rotated in a clockwise direction, as viewed in Figure 1, with the result that, after the throttle valve has been opened to a preselected extent, the element on the shaft 32 will be brought into engagement with the arm 5i and will positively partially open the choke valve irrespective of the temperatin'e and speed and load conditions of the engine. v In Figs. 5, 6, 6a, 7 and 8 ofthe drawing, the reference character I3 indicates the intake manifold of an engine similar to that shown in Fig. 1 and the reference character t9 a choke valve adjusting mechanism which includes a-bodyv El which is mounted on and secured to the intake manifold. n i

In the body of the mechanism shown in Figs.

5, 6, 6a, 7 and 8, there is provided a longitudinaily extending cylindrical bore 52 which is open at one end and closed atfthe other by va head 63. In the cylindrical bore E2, there is fitted a piston S which is urged away from the head end of the cylinder by a coil spring 6'! and to whose head end there is connected a transversely extending pin whose opposite ends project through lengthwise extending slots 5G in the wall of the cylinder distant from the head end. The pin 65 andthe slots 56 serve both to prevent rotation of the piston in the cylinder and to limit the movement of the piston axially of the cylinder in both directions.

into the head of the cylinder 62 from the upper side thereof, there extends a transverse bore 58 which terminates short of the lower side of the cylinder. The bore 68 is intersected by a bore 69 which extends through the head from the outer to the inner side thereof andby a bore 'l0 which extends into the Vhead from the inner side thereof and communicates at its outer end withv a transversely extendingA bore 'Hv which communicates with the interior of the intake manifold I3. The bores 68 and 'H are also interconnected by intersecting

bores

12 and 13 6 l which communicate, respectively, witlithe lower end of the bore 68 and with an intermediate portion of the bore 1|. Within the bore 68 whose upper end is closed by a screw plug 14, there is located a piston valve l5 which is urged upwardly by the coil spring 16 and in whose cylindrical Vwall there are provided two annular grooves 'l1 and '18.` l v In upwardly projecting ears 82 which are formed on the body 6l, there is journalled a shaft 'i9 which extends transversely of the cylinder S2 and projects outwardly beyond the ears. This shaft is connected to the piston 64 by arms fifi and 83 which are xedto the shaft and' links 8! whose opposite ends are pivotally connected, respectively, to the arms and 83 and the ends of the pin B5.

On the shaft 19 outwardly of the arm 88, there is journalled a sleeve 84 to whose outer end there is -iixed a cup-shaped housing 85 rto which is secured the outer end of a birnetal thermostatic coil spring 86 whose inner end is fixed to the outer end of the shaft 1S. The portion of the shaft i9 between the arm 80 and the inner end of the sleeve 84 extends throughv an elongated slot 87 in an arm 88 on which there is formed a rack 89 whose teeth Amesl'i withthose of a pinion Sii which is formed on `the adjacent end of the sleeve 84. On the outerend of the arm 88, there 'is provided a projection 9| which extends into a curved steppedslot 532k which'is formed in a plate 93 which is iixed to the body 6| A screw IIB which extends into the arm 8l) through an elongated slot H9 in the'arm 88 permits the arm 33 to move parallel to the length of the arm 88 but prevents relative' rotation of the arms 8D and 88 about the axis 'of the shaft 19.

On the shaft 19, outwardly of they arm 83, there is nxed a sleeve 94 and, outwardly of the sleeve 94, there is journalled on the shaft'lQ an arm 95 on which there is provided a, pin S6 which extends into a notch 87 in the sleeve and limits the angle throughout which the arm `can rotate with respect to the shaft. Thevarms and S3 `are connected by a Acoilspring `98 which encircles the sleeve 94 and whose ends are xed, respectively, to the arm 95 and the arm 83. To the outer end of the armv 95, there is pivotallyconnected a link 98 whose outer end is adapted to be connected to an arm which is xed to the shaft of the choke valve of the carburetor of an engine similar to that shown in Figure l.

It will be apparent fromthe drawingthat the mechanism illustrated in Figures 5, 6, 6a, 7 and 8 is adapted to be installed on an engine in the same manner as the mechanism illustrated in Figures 1, 2, 3 and 4.

The thermostatic spring 86 is so constructed and arranged that (l), as itstemperature rises,

it tends to rotate the housing 85 and the sleeve 'St in such a directiony (counter-clockwise, as viewed in Figure 7) that the rack and pinion 39-98 cause the projection 9| on the arm 88 to move upwardly in the slot82, (2), as its temperature falls, it tends to rotate the housing 85 and the sleeve 84 in such a direction (clockwise, as viewed in Figure 7') that the rack and pinion cause the projection 9| to move downwardly in the slot 92 and (3), when its temperature falls below a preselected minimum (e. g., 70 F. to 8Oc F), it will maintain the projection 8l in abutment with one of the steps on theflower edge of the slot 92. It will be apparent from the drawing and from what has previously been 75 said that the thermostatic spring i, when its temperature is below the mentioned preselected minimum, maintains the projection 9| in abutment with one of the steps on the lower edge of the slot 92 and, when its temperature equals or exceeds the mentioned preselected minimum, tends to regulate the position of the projection 9| radially of the slot 92 in accordance with its temperature and, consequently, in accordance with the temperature of the exhaust manifold II1 and that, functionally, the thermostatic spring 88 differs from the thermostatic spring 29 in that it does not directly affect the position of the choke valve.

It will, however, be noted (assuming that the choke valve is of the type illustrated in Figure 1 and hereinbefore described) that, when the engine on which the mechanism shown in Figures 5, 6, 6a, 7 and 8 is installed is operating, the ilow of air through the air intake conduit of the carburetor and the pressure within the intake manifold of the engine may affect the position of the choke valve. An increase in the rate of flow of air through the air intake conduit of the carburetor will tend to move the choke valve toward its fully open position, increase the tension in the spring 98, and through it rotate the shaft 1S in such a direction as to move the piston 64 toward the head end of the cylinder 62 and through the arm 80 and the screw I I8 move the projection 9| to the right (as viewed in Figure 7) in the slot 92 and that a decrease in the rate of flow of air through the air intake conduit will tend to decrease the tension in the spring 98 and permit the spring 61 to expand and, through the piston 64, the links 8| and the arms 80 and 83 rotate the shaft 19, in such a direction as to permit the choke valve to move toward its fully closed position and, through the mentioned elements and the screw I I8, move the projection 9| to the left (as viewed in Figure 7) in the slot 92.

Assuming that the engine on which the choke valve adjusting mechanism shown in Figures 5, 6, 6a, 1 and 8 is installed is operating under such conditions that the pressure within the intake manifold ls sufliciently low to maintain the piston valve 15 in such a position that the ends of the bore are connected by the groove 18, a decrease in the pressure within the intake manifold will tend to move the piston 64 toward the head end of the cylinder 62 and, through the links 8|, and the arms 80 and 83, rotate the shaft 19 in such a direction as to decrease the tension in the spring 98 and permit the choke valve to Amove toward its fully open position and as, through the mentioned elements and the screw II8, to move the projection SI to thepright (as viewed in Figure '1) in the slot 92 and that an increase in the pressure within the intake manifold will tend to permit the spring 61 to move the piston |54 away from the head end of the cylinder 62 and through the elements 8|, 80 and 83 rotate the shaft 19 in such a direction as to increase the tension in the spring 98 and through it move the choke valve toward its fully closed position and as through the elements 8|, 80, 83 and II8 to move the projection 9| to the left (as viewed in Figure '1) in the slot'92.

It will be noted that unless the pressure within the intake manifold of the engine on which the mechanism illustrated in Figures 5, 6, 6a, I and 8 is installed is below a preselected value, dependent among other things on the strength of the spring 16, the pressure within the intake manifold will be ineffective in determining the 8 position of the choke valve because while the pressure within the intake manifold is above this value, the cylinder 82 is vented to the atmosphere through the bore 69 and vthe bore 1I does not communicate with-the cylinder 62.

While, as suggested above, normally, the force exerted on the choke valve by the iiow of air through the intake conduit of the carburetor is transmitted to the shaft 19 and the force exerted by the pressure within the intake manifold on the shaft 19 is transmitted to the choke valve through the coil spring 98 which, consequently, functions as a spring load for the choke valve, it Will be noted that if these forces exceed a preselected value, the pin 96 will engage one end of the notch 91 and the forces will be transmitted positively from the shaft 19 to the choke valve and vice versa.

It will be understood from what has hereinbefore been said that every change in speed and/or load of an engine on which the mechanism illustrated in Figures 5, 6, 6a, 7 and 8 is installed will tend to shift the position of the choke valve but that no change in the position of the choke valve beyond limits determined by the pin 98 and the notch 91 can be effected without moving the pro- `iection 9| lengthwise of the slot 92. Consequently, since movement of the projection 9| lengthwise of the slot 92 throughout any considerable distance cannot occur without movement of the projection past one of the steps of the slot, since movement of the projection past one of the steps cannot occur unless the radial position of the projection is such that it can move lengthwise of the slot without engaging the radial wall of the step and since the thermostatio spring 86 tends to regulate the radial position of the projection in accordance with the temperature of the exhaust manifold of the engine on which the mechanism is installed, the position of the choke valve will be affected by the temperature as well as by the speed and load of the engine. It will be apparent from what has been pointed out in this paragraph that the mechanism shown in Figures 5, 6, 6a, 7 and 8 may be considered as a choke valve loading spring (98) whose characteristics are variable in accordance with the temperature and speed and load of the engine on which it is installed.

In the form shown in Figure 9, the choke valve regulating mechanism includes a base |00 which is adapted to be mounted on the intake manifold I3 oi' an internal combustion engine and on which there are provided upstanding ears |0I and |02 through which extend and in which are journalled a shaft |03. To the shaft |03, outwardly of the ear |02, there is fixed a choke valve operating arm |04 which is adapted to be connected to the choke valve of the carburetor of an engine similar to that shown in Figure l. To the outer side of the ear |0I, there is fixed an element |05 to which is secured a cup-shaped housing |06 into which the shaft |03 projects and to which is connected the outer end of a bimetal thermostatic coil spring |01 Whose inner end is iixed to the adjacent end of the shaft |03. The portion of the shaft |03 between the arms 0| and |02 is encircled by two hub-like elements |08 and |09. of which the former is fixed to the shaft, and the latter, which is connected to the former by a coil spring IIII which encircles the shaft |03 and whose ends are fixed, respectively, to the elements I 08 and I 09, is rotatably mounted on the shaft I 03.

To an arm I I I, which is formed on the element `the interior of the intake manifold engine on which thechoke valve operating mecha- IUS, there is .pvotally'connected one end of a which is formed on the base IUE). Within the cylinder IIli there isJlocated a coil spring IIE .which urges the piston upwardly in the cylinder.

Through the head of the piston, there extends a passage II E4 which is adapted to be connected tc nism shown in Figure 9is installed.

v It will be apparent from the drawing `that the mechanism illustrated in Figure 9 is adapted to be installed onan engine in the samemanner as the mechanisms illustrated in Figures l to S. Y

, The thermostatic springv I? is so. constructed andarranged that (1), as. its temperature rises, it tends to rotate the shaft m3 in such a direction as to move the choke valve (to which the arm |04 is adapted to be connected in a manner similar to that in which the arm 26 is connected to the choke valve I5) toward its fully open position and as to, through the element IBS, the spring I I0, the element I and the link I I2, move the piston IIS toward the head end of the cylinder I Iii, (2), as its temperature falls, it tends to rotate the shaft |63 in such a direction as to move the choke valve toward its fully closed position and as to permit the spring IIS to move the piston away from the head end of the cylinder and (3) that, whenA its temperature falls below a preselected minimum (e. g., 70 F. to 30 F.) it will, if unresisted, maintain the choke Valve in its fully closed position. From what has been said in the sentence next preceding this, it will be apparent that the thermostatic spring IG? functions similarly to the thermostatic spring 29 in that when itstemperature is below the mentioned preselected minimum, it tends to maintain the choke valve in its fully closed position and when its temperature equals or exceeds the mentioned preselected minimum it tends .to regulate the position of the choke valve in accordance with its temperature and, consequently, in accordance with the temperatureof the exhaust manifold I I'I. It will, however, be noted (assuming that the choke valve is of the type illustrated in Figure 1 and hereinbefore described) that, when the engine on which the mechanism shown in Figure 9 is installed is operating, the flow of air through the air intake conduit of the carburetor and the pressure within the intake manifold of the engine, as well as the temperature of the engine, affect the position of the choke valve. Itis obvious that an increase in the rate of flow of air through the air intake conduit of the carburetor will tend to move the choke valve toward fully open position and rotate the shaft Iil3 in such a direction as to coil up the thermostatic spring Iiii and the spring I IG and move the piston I I3 toward the head end of the cylinder I I4 and that a decrease ,in the rate of air iiow through the air intake conduit will tend to permit thermostatic spring Ill? and the springY IIIi to uncoil and the springIIB to extend and move the piston II3 away from the head end of the cylinder IIII and rotate the shaft |93 in such a direction as to move the choke valve toward its fully closed position. It is also apparent that a decrease in the pressure within the intake manifold of the engine will tend to move the piston I I3 toward the, head end of thecylinder H4, uncoil the spring I I0 and through it rotate the shaft |03 in such a direction as to uncoil the thermostatic spring I'I and move the choke valve toward its fully open position and that an increase in the I3 of the` pressure within the intake manifold will tend to permit the spring I I5 to expand, move the piston away from the head end of the cylinder, coil up the spring I I0 andthrough Vit rotate the shaft |03 in such a direction as to coil up the' thermostatic spring |01 and move the choke valve toward fully closed position.

While in Figures 5 to 9 the choke valves which the mechanisms showntherein are designed to operate have notibeen shown, and, consequently, the connections between the choke valves and the mechanisms have been shown incompletely, it

will be understood that the mechanisms shown in` Figures 5 to 9 will preferably be employed in conjunction with choke valves of the type shown in Figure 1 and will preferably be connected thereto by mechanism of the type illustrated in Figure l and hereinbefore described.

It may be well here to mention that, at some sacrifice of efficiencmbalanced instead of'unbalanced choke valves may be employed in conjunction with the mechanisms herein disclosed and/or throttle position variation actuated elements may be substituted for the manifold pressure variation actuated elements vherein disclosed.

Although I have shown and described preferred embodiments of my invention, it is to be understood that this has been done by way of example and not by way of limitation, and that the scope of my invention is to be determined only by the appended claims.

I claim:

l. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, a passage connecting theV carburetor with cylinders of the engine, an element actuated by variations in pressure withinthe passage opera-'- tively connected to the choke valve, and means rendering the element unresponsive "to variations in pressure within the passage when the pressure 'therein exceeds a predetermined rvalue.

2. The invention claimed in claim l, plus an element actuated by variations in temperature of the engine operatively connected to the choke valve. Y

, 3. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, a passage which connects the carburetor with a cylinder of the engine, a member which-moves upon variations in the pressure within the passage, a member which yieldingly opposes opening movement or" the choke valve interposed between the choke valve and the rst 'specified member, and a thermostat which positivelylimits movement of the rst specifiedV member.

4. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, a movable member, a member which yieldingly opposesv opening movement of the choke valve interposed betweeny the choke valve and the movable member, and a thermostat which positively limits movement of the movable member.

5. In an internal combustion engine, a carburetor in which there is incorporated a choke valve which isunbalanced so that flow of air into the carburetor tends to open it, a, passage which connects the carburetor with a cylinder of the engine, a member which moves upon variations within the passage, amember which yieldingly opposes opening movement of the choke valve interposed between the choke ,valve and the rst specified member, and a thermostat which positively limits movement of the first specified member.

6. In an internal combustion engine, a carbu- 11 retor in which there is incorporated a choke valve. a passage which connects the carburetor with a cylinder of the engine, a member which moves upon variations in the pressure Within the passage connected to the choke valve, means which renders the member unresponsive to variations in pressure when the pressure is beyond a preselected value, and a thermostat which positively limits movement of the member.

7. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, a passage which connects the carburetor with a cylinder of the engine, a member which moves upon variations in the pressure within the passage yieldingly connected to the choke valve, means which renders the member unresponsive to variations in pressure when the pressure is beyond a preselected valve, and a thermostat which positively limits movement of the member.

8. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, a passage which connects the carburetor with a cylinder of the engine, a member which moves upon variations in the pressure within the passage yieldingly connected to the choke valve, means which renders the member unresponsive to variations in pressure when the pressure is beyond a preselected valve, and a thermostat which positively limits movement of the member in both directions,

9. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, a passage which connects the carburetor with a cylinder of the engine, a member which yieldingly urges the choke valve toward its closed position, a member which moves upon variations in the pressure within the passage connected to the first specified member so that it mayr vary the force with which it urges the choke valve toward its closed position, and a thermostat which varies the eiec't of the specified members on the position of the choke valve.

10. In an internal combustion engine, -a carburetor in which there is incorporated a choke valve, a passage which connects the carburetor with -a cylinder of the engine, a member which yieldingly urges the choke valve toward its closed position, a member which moves upon variations in the pressure within the passage connected to the rst speciiied member -so that it may vary the force with which it urges the choke valve toward its closed position, and a thermostat which is connected to the choke valve independently of the speciiied members.

11. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, two stop elements of which one is movable into and out of contact with the other upon movement of the choke valve and the other is arranged so that forces applied to it through the iirst mentioned upon movement of the choke valve cannot move it and one is movable to change the position of the choke valve at which one of the stop elements contacts the other, and a thermostat by which one of the stop elements may be moved to change Vthe position of the choke valve at which one of the stop elements contacts the other.

12. In 'an internal combustion engine, a carburetor in which there is incorporated a choke Valve, a passage which connects the carburetor with a l2 cylinder of the engine, amember which moves upon changes in the pressure within the passage connected to the choke valve so that it may move it, two stop elements of which one is movable into and out of contact with the other upon movenent of the member and the other is arranged so that forces applied to it through the first mentioned upon movement of the member cannot move it and one is movable to change the position of the member at which one of the stop elements contacts the other, and a thermostat by which one of the stop elements may be moved to change the position of the member at which one of the stop elements contacts the other.

13. In an internal combustion engine, a carburetor in which there is incorporated a. choke valve, a passage which connects the carburetor with I. cylinder of the engine, va member which moves upon changes in the pressure within the passage, a shaft which is rotated upon movement of the member connected to the choke valve, two stop elements of which one is rotatable into and out of contact with the other upon `rotation of the shaft and is movable transversely of the shaft to alter its position with respect to vthe other stop element and a thermostat by which the rst mentioned stop element may be moved transversely of the shaft.

14. In an internal combustion engine. a carburetor in which there is incorporated a choke valve, a passage which connects the carburetor with a. cylinder of the engine, a movable member 'connected to the choke valve, a passage through which the pressure within the iirst specied passage is transmitted to the member so thatlt moves upon changes in the pressure in the iii-st specied passage, and means by which the 'second specified passage is closed so that the member is rendered unresponsive to changes in the pressure in the first specified passage when the pressure therein exceeds a preselected value.

15. In an internal vcombustion engine, a carburetor in which there is incorporated a choke valve. a passage which connects the carburetor with a T cylinder of the engine, a movable member connected to the choke valve, a passage through which the pressure 'within the flrst specin'ed pusage is transmitted to the member so that it moves upon changes in the pressure in the first specified passage, and means by which the second specied passage is closed and the pressure of the atmosphere is transmitted tothe member when the pressure in the nrst specified passage exceeds a preselected value,

CLARENCE J. SWIGERT.

REFERENCES CITED The following references 'are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,464,333 Pembroke s Aug. "7, 1923 1,723,936 Hifner Aug. 6, .1929 1,811,354 Joeck r June 23,1931 1,957,289 VPurpura -May 1, 1934 2,309,419 Sisson Jan, 2'6, 1943 2,348,033 Stanton May 2, .1951 2,362,346 Blake Nov, :7., 1944 2,421,733 Henning June 3, .1947