US2309419A

US2309419A - Mixture control for internal combustion engines

Info

Publication number: US2309419A
Application number: US567817A
Authority: US
Inventors: Glen R Sisson
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-10-09
Filing date: 1931-10-09
Publication date: 1943-01-26
Anticipated expiration: 1960-01-26

Description

Jan. 26, 1943.

G. R. SISSON MIXTURE CONTROL FOR INTERNAL COMBUSTION-ENGINES Filed Oct. 9, 1931 W M N... m m o s W 5 P N 6 n ,z mm 1 y 2 A s: 1J ZMWWHHIII IIIHHUH n f L Patented Jan. 26, 1943 .nef

MIXTURE ooN'rnoL Fon INTERNAL coMBUsTroN ENGINES Glen R. Sisson, Pendleton, Ind.

Application October 9, 1931,/ Serial No. 567,817

7 Claims. (Cl. 123-119) My invention is concerned with internal combustion engines of the type to which an explosive mixture is supplied by means of a carburetor or other, charge-forming device.

It is the object of my invention to provide a control mechanism for the carburetor or chargeforming device which control mechanism will serve, while the engine is being cranked, automatically to increase the richness of the explosive mixture to an extent depending upon temperature, and which will also serve to control the richness of the mixture in accordancewith temperature after the engine is started.

In carrying out my invention I provide in association with the carburetor a. mixture-enriching 'device such, for example, as the usual chokevalve, and I control this device jointly by a means responsive to temperature and a means which undergoes a change of position .or condition when the engine becomes self-operative after having been at rest. These various elements are associated in such a way that the richness of' the mixture formed in the carburetor is decreased when the engine becomes self-operative and is decreased further when the engine-temperature rises.

The accompanying drawing illustrates my invention: Fig; 1 is an elevation of the intake and exhaust manifolds and the carburetor of an engine showing my mixture-controlling device in position; Fig. 2 is anenlarged fragmental view similar to Fig. 1; Fig. 3 is a Vertical section on the line 3-3 of Fig. 1; Fig. 4 is a'view generally similar to Fig. l, but showing a modification of my invention; and Fig. 5 is a side elevation of an automobile engine showing a still further modification.

My invention is not concerned with any particular type of engine. In the drawing I have illustrated in detail, therefore, only certain parts of the engine such as the inlet manifold I0, the exhaust manifold II, and a carburetor I2- The carburetor embodies the usual throttle valve I3 and the customary choke-valve I4, the latter being located in the carburetor air-inlet I5. In embodying my invention/in association with the various engine-elements just referred to, the automatic control may be exerted on the choke. valve I4 which, as is well known, serves to in-1.v crease the richness of the mixture as it is moved toward closed position.

Various parts of the control mechanism are conveniently enclosed in a casing 20 which is preferably mounted adjacent the exhaust manifold I I of the engine. Within the casing I mount a transversely extending shaft 2| to which is anchored the inner end of a spirally wound bimetallic strip 22, the outer end of which bears upon an abutment provided at the upper end of a link 23. The lower end of the link 23 is connected to an arm 24 that is rotatable with the choke valve I4. .v

The bi-metallic strip 22 is but one example of a temperature-responsive element which may be used in carrying out my invention. In the ,n ar- *rangement illustrated in the drawing, the strip is arranged with the metal of higher expansioncoeiiicient toward the outside in order that the free end of the strip 22 may rise and permit upward movement of the link 23 to open the choke valve I4 upon an increase in the temperature to which the bi-metallic strip 22 is sub- Jected.

. Fixed to the shaft 2| I provide a downwardly extending arm 26 operatively connected to a piston rod 21 which carries a piston 28 disposed in an associated cylinder 29. A yielding means, such as a spring 3|, acts upon the piston 28 or piston rod 21 tending to move it to the left in Fig. 1, thus tending to depress the free end of the birmetallic strip 22 to lower the link 23 and move the choke-valve I4 toward closed position. The right-hand ,end of the cylinder 29 is connected through a suitable conduit 32 with the intake manifold I0 of the engine in order that the piston 28 may be subjected to the pressure existing in the intake conduit of the engine above the throttle valve I3. The' left-hand end of the cylinder 29 is in communication with the atmosphere.

' Some means, a particular form of which will hereinafter be described, is provided for maintaining theupper end of the link 23 in contact with the free end of the bi-metallic strip 22 in order that the choke valve I4 will be moved toward open position as the temperature increases and the free end of the bi-metallic strip 22 moves upward.

When the engine is at rest, and therefore com-v paratively cold, the parts of my device occupy the respective positions illustrated in Fig. l-andin full lines in Fig. 2. That is, the choke-Valve I4 is closed, and the piston 28 is displacedfrom the right-hand end of the cylinder 29. If, under these conditions, the engine is cranked for the purpose of starting it, an enriched mixture will pass through the intake manifold II] to the engine. The ow of this mixture will be accompanied by a slight drop in pressure within the manifold I0; but since the cranking speed of the engine is slow, this pressure-drop will be low and will be insuilicient to move the piston 28 to the right in opposition to the force exerted upon it by the spring 3|. When, however, the engine becomes self-operative, the rate of mixture-flow through the manifold I8 increases, and the pressure within the manifold drops to -a value suiiicient tov cause the piston 28 to move to 'the right. The resulting movement of the piston rod 21 rocks the shaft 2| in a counter- 10 clockwise direction, elevates the free end of the bi-metallic strip 22, and causes a partial opening of the choke-valve I4, as indicated in dotted lines inFig. 2, thus decreasing the richness of the mixture supplied to the engine by the car- '15 buretor |2:` As the engine continues to run, its j temperature., increases, thus causing a further elevation of the free-end of the bi-metallic strip 22 and a further opening of the choke-valve il. The parts are arranged in such a manner that when the engine reaches normal operating temperature the choke-valve Il will be substantially completely open. Manufacturers of carburetors frequently em- 3 ploy a choke valve which is unbalanced, beinj,v

to mov 4so arranged that air-flow past it tends it toward open position. This tendency is, of y course, especially pronounced when the chokevalve is closed, and may be so pronounced as to cause partial opening of the choke-valve when it would otherwise be held closed by the bimetallic strip 22. To prevent any such action, I may employl means for locking the choke-valve in closed position until after the engine has become self-operative. In Figs. 1 and 2, such a locking means in the form o f a toggle is illustrated. The toggle lock just referred to comprises two links and 38 which are pivotally interconnected at 31. The upper end of the upper link 35 is pivoted at a fixed point in the casing 20; while the lower end of the lower link 36 is pivotally connected to the choke-valve adjusting link 23. Acting between the toggle links I provide a spring 38 which tends to raise the choke-,valve adjusting link 23. The points of attachment of the spring 38 to the links 35 and 38 are oiI-set to the right of the centerlines of the respective links in order that the spring 38 will tend to move the center toggle-pivot 31 to the left when the three pivot points of the toggle are in line, which condition exists when the choke-valve |4 is completely closed. One of the toggle-links, here shown as the link 3i, is provided with an abutment ll which engages-the other toggle-link to limit leftward movement of the middle toggle-pivot I1.

. With the construction as described, the chokevalve I4 will be held in closed position until the toggle comprised by the two links 3B and 33 is broken; for the choke-valve adjusting link 23 cannot move upward and the choke-valve cannot open as long as the middle toggle-pivot 31 lies to the left of the line through the end togglepivots.

By disposing the abutment 48 in line with the end of the piston rod 21, the toggle may `be broken by rightward movement of the piston rod 21 which occurs when the engine becomes selfoperative. To permit the breaking of the toggle without disturbing the shaft 2|, the connection 70 between the arm 26 and the piston rod 21 may have a degree of lost-motion suicient to permit the piston rod 21 to move to the right far enough to break the toggle without rocking the shaft 2|.

Except when the toggle is locked, as illustrated in full lines in Fig. 2, the spring 38 tends to hold the link 23 in contact with the free end of the bimetallic strip 22, as is clear from the dotted-line position shown in Fig. 2.

Instead of subjecting the piston 28 to the pressure existing within the intake manifold I0, it may be subjected to some other pressure which undergoes a material change when the engine becomes self-operative. This, in Fig. 5, I have illustrated an arrangement in which the lefthand end of the cylinder 29 is closed and connected to an oil-lineof the oiling system of the engine. Atthe low speed of cranking, the pressure within the oil-circulating system of the engine will be insuficient to displace the piston againstthe action of the spring 3|; but when the engine becomes self-operative, the pressure exerted by the oil on the piston 28 is increased to such an extent that the piston is moved to the right in the same manner as that in which it is move'd in the vconstruction illustrated in From tl'ie construction described, it will be apparent that the position of the choke-valve, and therefore the richness of the mixture produced in the carburetor |2, will be dependent upon whether or not the engine is running under its own power and also upon engine temperature. As previously described, the device provides a temporarily enriched mixture during the starting operation and abruptly decreases the richness of the mixture when the engine becomes self-operative, and then gradually decreases the richness of the mixture as the engine-temperature increases until a normal mixture is produced when the engine reaches normal operating temperature. Should the' engine be stopped after having reached normal temperature, differentiai pressure on the piston 28 will be relieved and the spring 3| will move the piston to the left to depress the free end of the bi-metallic strip 22 and move the choke-valve toward closed position. The extent of the choking thus produced will depend upon engine temperature, being greater when the engine is cold than when the engine is hot. 'I'his is a distinct advantage of my device for it provides a partial and desirable choking action during starting of the engine even when the engine is hot.

If desired, the strength of the spring 3| may be made such as to exert a control on the chokevalve I4 While the engine is running, in accordance with varying conditions. Thus, it is well known that a cold engine will operate with a predetermined degreyof choking at low speeds -but that it will fail to` operate `satisfactorily as the result of too lean a mixture if the throttle is suddenly opened to increase engine-speed. Variations of the pressure "-within -the intake manifold are such as to enable me, by properly proportioning the spring 3|, to provide an increased choking action if the throttle is suddenly opened when the engine is cold. That is, the pressure-drop within the intake manifold of the engine varies from around one inch of mercury during cranking 'with closed throttle or choke valve to about sixteen inches of mercury when the engine is self operative at low speeds and closed throttle. With the throttle I3 completely or nearly completely open, the pressure-drop in the manifold I0 will ordinarily not be less than ve inches of mercury even at low engine speeds and Will gradually increase as the engine speed increases.

If lthe spring 3| is so proportioned that it will hold! the'pistomz totheileftwarderidcf its move-w ment against apressure drop 'ofi- .one inch-ofY mer cu`ry:in:rthevintake-' manir`old,=K completely `col lapse .iandzpermit ektrerne right-ward movement -of s c. the. pistonv whenithefpressure-drop within the' is connected through the ignition ysvviiichfltt one. l terminalofthe-:battery EGraZnd-thetotheraterminal of thebatterysisgrounded@c, at l 5 In"1iig.'4\ thelpartsrofi thtpdevi'cejust-described.V

other endof the fw'inding oflthe. electromagnetSZ-.t

manifoid r1.0 l'is fi'nffthei :neighborhood =o sixteen finchs tot mercury', andwillv undergo 'only av 'parL tiall lcollaipsetwhenfthepressure :drop Within the' manifdld'fs'm'fthe :neighborhoodrof -iive inches '-off v the-leftward limit 'of its 'movement ithus producing its hiaxni'mii l effctf 'in enrichening -thefI mixture.

power,l l the' piston l128' Vxfwillf' mov'e fto" f the' extreme rightward Ilimitffits? movement and will' produce` the minimum effect it-is`capable ofexercisinglfl the engine-speed increases in response v,tog-the .'i-

opened throttle, the pressure-drop will increase IIL-Fia ai; hereniging@ en ,embodiment of imy lrivehtion in association with'an automatic mixture-control? device' fs'uch las is *set forth'and l? describ`ed in my co-pending applicationerial No. 532,376, iiled April 23, 1930, now Patent No.

2,127,653. In that devig-thetchoke-valveIll is?" controlled by changes in the position of a movable member 50 which in turn is controlled by a temperature-responsive element 5| responsive to engine temperature y and my.. an .electro-magnet 52. In my co-pending 'application `just referred to, the

the electric motor of the engine-starting device so that it is energized to draw the member 50 downward and move the choke valve il toward closed position Whenever the engine-starting device is operative. The extent to which the chokevalve i4 is closed by energizatiorl of the magnet 52 and the extent to which it is opened after the magnet 52 is de-energized depend upon the position of the temperature-responsive element 5I which, through a movable member 53, adjusts stops 54 and 55 that limit closing and opening movements of the -choke-valve I4 respectively.

In associating the invention of this application with the device just described, the magnet 52, instead of being arranged to be controlled by the starter-switch is connected to a battery' 56 through the switch 51 that is usually employed to connect the battery to the engine ignition system, one part of which is indicated at 58. In series with the magnet 52,.I place a pressureresponsive switch which is controlled by pressures in the intake manifold I0 of the engine. This smch may take different forms, the switch shown comprising a chamber B0 one side of .which is defined by a movable diaphragm 6I. The chamber 60 is in communication with the intake manifold H) of the engine through a suitable tube 62. The diaphragm 6l carries a contact 63 which is grounded and which is arranged to engage a stationary contact 64 that is connected to one end of the winding of the electromagnet 52. The

Cil'

are shownti'ntherpositionstheysoccupy when' the engine isi coxnparativ'elyfcoldfantiy is'f'riot--ini operthe stop s4. Tilefpartsff'taib'r'ess fear stonata' switch are so aftirisertautae 'iir'ss'fwmam the intake manifold during the cranking oper- 20 ation is insuicient to move the contact 63 out of engagement with the contact 64; and as a. result. the choke-valve, during the cranking operation.

remains in the position it assumed when the magn et 52 was energized. As soon, however-,as the 25" engii'ebegin's .to run. under its own power, pressure within the intakgmanifold-(LB dropsztand thegntact 63 is moved out of engagement with fthifstationary contact 64, thus interrupting the supply oi' current to the magnet 52 andvpermltting "theichoke-yal've move-toward open fposition to .se attent .determined Pri-the, @sitios 0f -zthefswv 55. As the enginecontinues vrun and its tempeiatur increasesl, tlie'lstop 5511s' riovei'l upwardly under thelcontrolfof` thetemperature-responsive element 5|', until the choline-valve M reaches substanti'ally-'wide-fpen 'position when the n"engine reaches normali*operating,ftemperature-V I claim as my invention:

l. In combination with an internal combustion engine having a carburetor, an adjustable mixture-enriching device for said carburetor, a movable member, temperature-responsive means acting between said movable member andsaid device and nonresiliently connected to the latter,

45 and means associated with the engine for moving said member in one direction when the engine is running and in the other direction when the engine stops.

2. A control mechanism for an inter-ral combustion engine carbureter having a choke valve comprising, means for locking the valve closed to start the engine, means actuated by oil pressure in the engine -for unlocking the valve, and a. thermostat for controlling the opening of the valve as a function of temperature.

3. A control mechanism for an internal combustion engine carbureter having an unbalanced choke valve comprising, a lever connected to said valve, latch means engaging said lever to hold the valve closed for starting, oil pressure actuated means for moving said latch means to release the valve when the engine res, a thermostat tensioned to hold the valve closed, and means for decreasing the tensionof the thermostat when the engine res to permit the valve to open under the control of thc thermostat.

4. In an internal combustion engine having an intake manifc.d, a carbureter attached to said manifold, a pump driven by said engine, a device for controlling the richness of the fuel mixture supplied to said engine by said carbureter, a h'eat responsive device for controlling the operation of said mixture controlling device, and means responsive to pressure derived from said pump for further controlling the operation of said mixture control device.

5. The invention set forth in claim l with the addition that said temperature-responsive means and movable member are located remote from said mixture-enriching device, a rigid link connected to said mixture-enriching device for operating it and extending into association with said temperature-responsive means. said temperature-responsive means serving to operatively interconnect said movable member and said link.

' 6. The invention set forth in claim 1 with the addition that said mixture-enrichingr device is an unbalanced choke valve located in the airadmission passage or the carburetor and tending to swing toward open position under the inuence of the air impinging upon it.

7. In combination with an internal combustion engine having a carburetor, an adjustable mixture-em'iching device for said carburetor, a movable member, temperature-responsive means acting between said movable member and said device and non-resiliently connected to the latter, said movable member being movable between two positions in the first of which it adjusts said mixture-enriching device to cause production of a relatively rich mixture and in the second of which it adjusts said mixture-enriching device to cause production of a relatively lean mixture, and means associated with said engine for controlling theposition of said movable member and acting to maintain said movable member in said first position when the engine is being cranked and in said second positon when the engine is running under its own power.

^ GLEN R. SISSON.

. QERTIFIcAfL'E` oF CORRECTION. j pat-.ent No. 2,5o9,19. f Jamiwyze, 191g.

GLEN n. sIssoN.

It is hereby certified that error appears in the printed specification of the abo ve numbered patent requiring correction es follows: Page Il, first column, lines 5 and 12, for "claim l" residv claim 7"; and that the said Letters Patent should be read with. this correction therein that the same may conform to the record of the case in the Patent Office.

signed and sealed 1111s 25rd may -cr'Nuvember,- A; 1yr-19M.4

Henry' Van Arsdale,

(Seal) Acting Commissioner of Patents.