US2956558A - Means for starting and operating internal combustion engines - Google Patents

Description

Oct. 18, 1960 2,956,558

MEANS FOR STARTING AND OPERATING INTERNAL COMBUSTION ENGINES Filed NOV. 14, 1957 M. F. STERNER ETAL 2 Sheets-Sheet 1 INVENTORS A451 w/v E 5 rams 12 mm yam) ,4 TTOR/VEY Oct. 18, 1960 M. F. STERNER ETAL 2,956,558

MEANS FOR STARTING AND OPERATING INTERNAL COMBUSTION ENGINES Filed Nov. 14, 1957 2 Sheets-Sheet 2 INVENTORS M54 V/A/ STE/PA/E/P, BY MAP/0N l. 544/72 5) (2 Jzvsip 6 FM #015.

U at QMQL ,4 TTOE/VE Y United States Patent MEANS FOR STARTING AND OPERATING ETERNAL COMBUSTION ENGINES Melvin F. Sterner, Bloomfield Hills, Marion L. Smitley, Huntington Woods, and Joseph E. Francis, Utica, Mich., assignors to Holley Carburetor Company, Van Dyke, Mich., a corporation of Michigan Filed Nov. 14, 1957, Ser. No. 696,508

9 Claims. (Cl. 123-119) This invention relates to internal combustion engines, and more particularly to means for controlling the starting and subsequent warm-up period operation thereof.

Most internal combustion engines and particularly those employed to drive motor vehicles are now equipped with a so-called automatic choke, the main purpose of which is to provide a relatively rich fuel-air mixture for the engine on cold starting and until the engine has reached normal operating temperature. The most common type of automatic choke is that having an ofi-set choke plate, a vacuum piston responsive to engine vacuum for opening the choke plate and a single thermostatic coil spring to resist such opening, with the resistance thereof decreasing with increasing engine temperature.

However, there are still some objections to the use of the above type automatic choke. In the first place, the use of a thermostatic coil spring opposing a vacuum piston tends to limit the calibration of the choke to engine requirements; that is, with any given piston and single spring combination, certain compromises have to be made which may result in departures from exact engine requirements. Secondly, the vacuum piston is a relatively expensive part of the choke assembly, and it is subject to malfunctions such as sticking.

The latter objections are related in that it is common practice to provide a predetermined bleed around the piston so that engine vacuum can also draw air heated by a stove in the exhaust manifold into the thermostatic coil spring housing as an indication of engine operating temperature. A separate clean air line must, nevertheless, be provided between the inside of the air cleaner and the stove to prevent air-borne dirt from causing the piston to stick. Also, great care must be taken to prevent and repair exhaust leaks at the stove, since this will very quickly cause the piston to stick and malfunction. This sticking sometimes occurs despite these precautions.

It is now proposed to provide an automatic choke assembly in which there is no vacuum piston and in which there is a combination of resilient means opposing choke plate opening, one of which is a thermostatic coil spring and the other of which is a mechanical spring. With the use of the spring combinations contemplated by the invention, a choke mechanism may be provided that functions' just as well as or better than a choke having a vacuum piston and without the above objections of a piston.

The invention will be best understood from the following detailed description and claims, reference being had to the accompanying drawings in which one embodiment of the invention is shown by way of example and wherem:

Fig. 1 is a side elevational view, with portions thereof cut away and in cross section, illustrating a carburetor having an automatic choke embodying the invention in its preferred form.

Fig. 2 is a fragmentary and elevational view, with portions thereof cut away and in cross-section, taken on the 2,956,558 Patented Oct. 18, 1960 plane of line 2-2 of Fig. 1 and looking in the direction of the arrows.

Fig. 3 is a perspective view of a modified choke valve.

Fig. 4 is an enlarged fragmentary perspective view of a portion of Fig. 2.

Figs. 5 and 6 are views similar to Fig. 4, but illustrating other embodiments of the invention.

Referring to the drawings in greater detail, Figures 1 and 2 illustrate a typicalautomotive carburetor 10 having an automatic choke -12 embodying the invention. This carburetor, which will be described in detail only to the extent necessary to disclose the invention, includes anupper section 14 having anair intake passage 16 to supply combustion air to the lowerthrottle body portion 18. The usual air cleaner would be fitted to theflange 20 so that clean air would be supplied to the engine.

Achoke valve 22 for controlling the flow of air through thepassage 16 is mounted on thepivot shaft 24 in a manner so that the plate is oiiset on the pivot; that is, the lower ordownstream portion 26 of the plate, when the plate is fully closed as shown by Figures 1 and 2, is substantially longer than the upper orupstream portion 28 so that when the engine is started the flow of air through thepassage 16 will tend to open thevalve 22. Furthermore, the unbalance is also such that if there were nothing to restain it, the choke valve would fully open due to gravity.

Thechoke valve 22 may have a secondary or apoppet valve 23 therein, as illustrated in Fig. 3. This secondary valve may comprise aplate 25 mounted on the lower surface of thevalve 22 by means of twopins 27 which are biased bysprings 35 away fromplate 22 in such a manner so as to normally cause theplate 25 to closeopenings 29, 31 and 33 in valve '22. Thissecondary valve 23 may be used in order to obtain additional control of the fuel-air ratio once the engine is started; that is, as soon as the engine starts a pressure differential is created across thechoke valve 22 and thesprings 35 are overcome by this effective force acting onplate 25. In this manner, the choke 1 2 may allow additional air to be admitted, thereby satisfying the engine air requirements for those particular operating conditions.

The lowerthrottle body portion 18 contains or has mounted thereon the usual carburetor structures, such as the primary and/or the secondary induction passages each having a venturi, the associated throttle plates and throttle shafts, the float chambers, the fast idle mechanism, the accelerating pump, etc. Since these structures are not important to the invention, they need not be shown and/ or described in detail.

Referring again to Figures 1 and 2, an automaticchoke housing assembly 30 may be secured to the side of thethrottle body portion 18, preferably adjacent theend 32 of the primary throttle shaft. Theassembly 30 may include a cast or otherhollow housing 34 secured to thethrottle body 18 by any suitable means such asscrews 36, a plastic or otherinsulating type cover 38 secured byscrews 40 and aclamping ring 41 and a separatinggasket 42 constructed from a material having heat insulating properties.

The housing 34- may be provided with ajournal 44 and bearing 46 adapted to receive theshaft 48 which is free to rotate within thebearing 46. Alever 50 having a laterally extendingportion 52 is secured for rotation with theshaft 48 and within thehousing 34 and thecover 38, with theportion 52 being adapted to move along an arcuate slot 54 in thegasket 42. The other end of theshaft 48 is provided with alever 56 which is also secured for rotation with theshaft 48, and asuitable link 58 is pivoted at the ends thereof between thelever 56 and thelever 60 which is secured for rotation withthe choke 3shaft 24. Thelink 58 may extend through asuitable opening 62 in theair cleaner flange 20.

Thecover 38, which is preferably constructed from a heat insulating material, comprises a hollow body of suitable proportions to house the structure to be described; it includes astem 64 rigidly secured to the center of theend Wall 66. Thestem 64 is of sufficient length to accommodate thethermostatic coil spring 68 and themechanical spring 70. One end ofthermostat 68 is received and anchored in slot 72 in thestem 64.

Figure 4 better illustrates the arrangement of the thermostatic and mechanical springs within the choke assembly 12. Themechanical spring 70 is generally of a torsional form having any desired number of coils 71 wound loosely about therod 64 to permit rotation of theentire spring 78 about thepivot 64. The two arms extending from the coiled sections haveportions 74 and 88 which are formed so as to pass over the outer coil ofthermostatic spring 68. In conjunction withportion 88, anabutment 76 that may be of generally loop shape is formed within the spring; thisabutment 76, in turn, has anothersegment 97 which extends in a generally arcuate manner aboutthermostat 68 and passes through anopening 90 formed in theend 86 of the thermostat. Theend 92 ofspring 70 may be bent so as to prevent its slipping out of thehole 92.

Portion 74 andend 92 ofspring 70 are positioned in a manner to containend 86 of the thermostat constantly between them. Theabutment 96 is placed betweenend 86 of the thermostat andportion 52 ofarm 50 so as to contact said arm and offer initial resistance to the opening of the choke valve.

Provision may be made to heat thethermostatic coil spring 68 by air heated in any suitable manner, as by the exhaust manifold, as an indication of engine operating temperature. For instance, the heated air may be drawn from a stove in the exhaust manifold throughpassage 78 and into thethermostatic spring chamber 80 defined by theinsulating gasket 42 andcover 38 at a predetermined rate by means of a passage 82 having arestriction 83 and leading from thechamber 84 to the engine intake manifold; communication betweenchamber 80 and thechamber 84 may be provided by the arcuate slot 54 in theinsulating gasket 42. This structure is well known in the art and need not be described in great detail.

In Figs. 1 and 2, thechoke plate 22, thechoke housing assembly 30 and the connectinglinkage 58 are shown in the position they would be when the engine is cold and not operating; that is, thethermostatic coil spring 68 is unwound to load the mechanical spring 7i) so that theabutment 76 thereof engages theportion 52 oflever 50 and urges thelever 50 to the left, as shown in Fig. 2,.

to raise thelink 58 and close theotfset choke plate 22 against the force of gravity tending to open it. Thethermostatic coil spring 68 is prevented from completely unwinding by the engagement ofportion 74 ofspring 70 withend 86 ofthermostat 68.

As soon as the cold engine starts after cranking, the flow of air to the engine past the throttle valve, which may be held in the partially opened position by any suitable fast idle mechanism, exerts an additional opening force on theunbalanced choke plate 22. This additional opening force overcomes the force ofspring 70,cansing lever 50 to rotate clockwise untilportion 52 ap proaches or actually comes into contact with theend 86 ofthermostat 68 depending upon the force of theintermediate spring 70. As the engine temperature increases, thethermostat 68 Will wind in the clockwise direction, thereby permitting thechoke valve 22 to progressively open according to temperature. It is evident that the degree of choke opening is dependent on not only temperature but also on the air loading of or the pressure differential existing across the choke valve. Therefore, as the thermostat continues to wind, the loading on the choke decreases and as it decreases the effective force acting against themechanical spring 70 diminishes there by causing theend 86 of the thermostat to walk" away from thearm 50. This insures that the richness of the fuel air mixture is not dependent only on the temperature but also on the air requirements of the engine. This Walking away action of theend 86 of thethermostat 68 continues until thechoke valve 22 is fully opened, at which time further movement ofarm 50 is arrested while further movement ofthermostat 68 andspring 70 may continue. When thethermostat 68 reaches its point of maximum travel depending on temperature, a substantial angular displacement may result betweenabutment 76 andportion 52 ofarm 50.

It can readily be seen that this choke mechanism would also act somewhat as an anti-stall device. That is, if during the Warm-up period the engine began to stall, the air loading would diminish on the choke valve, thereby allowingspring 70 to rotate thechoke valve 22 in the closing direction to provide a richer fuel-air ratio.

When the engine is shut down andthermostat 68 begins to cool, it unwinds in the counter-clockwisedirection moving spring 70 with it. When the thermostat andspring 70 have moved sufficiently,abutment 76contacts portion 52 ofarm 50 and forcibly movesarm 50 to the left; this, in turn, causes thechoke valve 22 to move towards the closed position.

Figures 5 and 6 are modifications of the invention, also employing combinations of thermostatic and mechanical springs. Themechanical springs 94 of both Figures 5 and 6 are identical in shape, that is, they are of generally torsional form, being coiled aboutextension 64, and they havearms 96 and 98 and aportion 100 bent over so as to contact theend 86 ofthermostat 68.

When thechoke valve 22 is closed, the embodiment of Figure 5 will act in the same manner as that of Figures 1, 2 and 4; that is, the unwinding ofthermostat 68 will cease when an equilibrium of forces is obtained between themechanical spring 94 andthermostatic spring 68. However, there is a slight difference in the operation at the time that thechoke valve 22 is in its fully opened position. When thearm 50 has moved so as to reach its fully opened position, thespring 94, since it has a tendency to move to its free state, will continue to exert some force uponarm 50 in a decreasing manner in accordance with engine temperature because of the winding action of the thermostat.

The modification of Figure 6 has astop pin 102 fixed at one end within thechoke assembly housing 34 and projecting into the path ofend 86 of the thermostat when it is unwinding. This is used so as to limit the initial stress applied to themechanical spring 94 in the closed choke position. Otherwise the operation is the same as that of Figiuge 5 and generally the same as that of both Figures 4 an The modifications of the invention shown and described herein are for the purposes of illustration, and no limitations are intended, except as set forth in the appended claims.

What we claim is:

1. A carburetor or other fuel control for an internal combustion engine, comprising a body having an air intake passage, a pivoted choke valve in said passage to control the flow of air therethrough, said choke valve being offset so that the flow of air through said passage tends to open said valve, suitable linkage connected to said choke valve and terminating at the opposite end thereof in a pivoted lever having a. laterally extending arm movable with said choke valve, a thermostatic element having one end secured to said body and the free end thereof positioned in the path of travel of said arm, and mechanical spring means interposed between said arm and the free end of said thermostatic element.

2. A carburetor or other fuel control for an internal combustion engine, comprising a body having an air intake passage, a pivoted choke valve in said passage to control the flow of air therethrough, said choke valve being offset so that the flow of air through said passage tends to open said valve, suitable linkage connected to said choke valve and terminating at the opposite end thereof in a pivoted lever having a laterally extending arm mov able with said choke valve, a thermostatic element having one end secured to said body and the free end thereof positioned in the path of travel of said arm, and mechanical spring means interposed between said arm and the free end of said thermostatic element, said thermostatic element when cold urging said arm through said mechanical spring to close said choke valve and initial opening of said choke valve compressing said mechanical spring to an extent dependent upon temperature.

3. A carburetor or other fuel control for an internal combustion engine, comprising a body having an air in take passage, a pivoted choke valve in said passage to control the flow of air therethrough, said choke valve being offset so that the flow of air through said passage provides a force to open said "alve, linkage connected to said choke valve and movable with said choke valve, a thermostatic element having a portion thereof positioned in the path of travel of said linkage, and mechanical spring means interposed between said linkage and said portion of said thermostatic element, said thermostatic element on decreasing temperature urging said linkage to close said choke valve through said mechanical spring and initial opening of said choke valve compressing said mechanical spring to an extent dependent upon temperature, and the connection between said thermostatic element and said mechanical spring being such that said element moves said spring bodily on increasing temperature.

4. In an engine carburetor or other fuel control, a body having an air intake passage, a pivoted choke valve in said intake passage to control the flow of air therethrough, said choke valve being offset on its pivot so that the flow of air through said passage and gravity provide forces to open said choke valve, a lever having a laterally extending arm and being pivoted on said body, linkage between said choke valve and said pivoted lever, means adapted to oppose the opening of said choke valve including a thermostatic coil spring subjected to engine temperature and having its inner end secured to a shaft secured to said body, said thermostatic spring being adapted to unwind with decreasing temperature and to wind up with increasing temperature and the outer end of said thermostatic spring being formed to provide an abutment variably positioned in the path of travel of said arm in accordance with engine temperature, and a mechanical spring formed intermediate its ends to be pivotallyanchored on said shaft and having the free ends thereof positioned between said arm and said abutment to spread the same, said mechanical and said coil springs being arranged such that initial opening of said choke valve is accomplished by compressing said mechanical spring against the tension of said coil spring regardless of engine temperature, and subsequent opening of said choke valve being dependent upon the extent of windup of said coil spring with increasing engine temperature.

5. In an engine carburetor or other fuel control, a body having an air intake passage, a pivoted choke valve in said intake passage to control the flow of air therethrough, said choke valve being offset on its pivot so that the flow of air through said passage provides a force to open said choke valve and said choke valve having a spring loaded poppet valve associated therewith, said poppet valve being opened by the flow of air to said engine at times when said choke valve is not fully open, a lever having a laterally extending arm and being pivoted on said body, linkage between said choke valve and said pivoted lever, means adapted to regulate the opening of said choke valve including a thermostatic spring subjected to engine temperature and having one end secured to a shaft secured to said body, the other end of said thermostatic spring being formed to provide an abutment variably positioned in the path of travel of said arm in accordance with engine temperature, and a mechanical spring formed intermediate its ends to be pivotally anchored on said shaft and having the ends thereof positioned between said arm and said abutment, the arrangement of said mechanical and said coil springs being such that initial opening of said choke valve compresses said mechanical spring and subsequent opening of said choke valve is dependent upon the relaxing of said coil spring with increasing engine temperature.

6. In an internal combustion engine, a carburetor or other fuel control comprising a body having an air intake passage, a pivoted choke valve in said intake passage to control the flow of air therethrough, said choke valve being offset on its pivot so that the flow of air through said passage provides a force to open said choke valve, a 'lever having a laterally extending arm and being pivoted on said body, linkage between said choke valve and said lever, means adapted to regulate the opening of said choke valve, said means including a thermostatic spring subjected to engine temperature and having one end secured to a shaft secured to said body, the other end of said thermostatic spring being variably positioned in the path of travel of said arm in accordance with engine temperature, and a mechanical spring pivotally anchored on said shaft and having portions thereof positioned be tween said arm and said abutment, the arrangement of said mechanical and said thermostatic springs being such that initial open-ing of said choke valve is substantially controlled by said mechanical spring and subsequent opening of said choke valve is substantially controlled by said thermostatic spring.

7. In an internal combustion engine, a carburetor or other fuel control comprising a body having an air intake passage, a pivoted choke valve in said intake passage to control the flow of air therethrough, said choke valve being oifset on its pivot so that the flow of air through said passage provides a force to opensaid choke valve, a lever pivoted on said body, linkage between said choke valve and said lever, means adapted to regulate the opening of said choke valve, said means including a thermostatic element subjected to engine temperature and having a portion thereof formed to provide an abutment variably positioned in the path of travel of said lever in accordance with engine temperature, and a mechanical spring positioned between said lever and said abutment, the arrangement of said mechanical and said thermostatic element being such that initial opening of said choke valve is more dependent upon the rate of said mechanical spring and subsequent opening of said choke valve is more dependent upon the effect of increasing engine temperature on said thermostatic element.

8. A control device for positioning the choke valve of a fuel control for an internal combustion engine, comprising a thermostatic element having one end thereof secured in a stationary position and the other end free and capable of movement in response to variations in temperature, linkage means connecting said choke valve to a lever having an extending arm portion, said arm portion being adapted to rotate in accordance with choke valve movement and having a path of travel substantially co-planer with the path of travel of said free end of said thermostatic element, and a mechanical compression spring placed in series between said arm portion and said free end of said thermostatic element, said spring being formed so as to have its end portions engageable with said free end of said thermostatic element in a manner so as to prevent said spring from ever attaining its free length regardless of the respective positions of said choke valve and said free end of said thermostatic element.

9. A carburetor or other fuel control for an internal combustion engine, comprising a body having an air intake passage, a pivoted choke valve in said passage to control the flow of air therethrough, said choke valve being offset so that the flow of air through said passage tends to open said valve, linkage means connected to said choke valve and terminating at the opposite end thereof in a pivoted lever having a laterally extending arm movable with said choke valve, a thermostatic element having one end secured to said body and the free end thereof positioned in the path of travel of said arm, mechanical spring means interposed between said arm and the free end of said thermostatic element, and a rigid stop member positioned in the path of travel of said free References Cited in the file of this patent UNITED STATES PATENTS 2,336,810 Smith D66. 14, 1943 2,420,917 Sutton et al May 20, 1947 2,421,733 Henning June 3, 1947 2,423,059 Win kler June 24, 1947

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