US2423059A - Carburetor - Google Patents

Description

June 24, 1947. A. H. wlNKLER CARBURETOR Filed Feb. 18, 1943 2 Sheets-Sheet 2 HVVHVTOR H2 BERT H. W//vkLER W, m w e q. H umm Y Ill Il| n B Q A w f ww. J me If, L \A1\ w 4 7 e Z r, M Mw Patented June 24, 1947l CARBURETOR Albert H. Winkler, South Bend, Ind., assigner to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware y Application February 18, 1943, Serial No. 476,263

7 Claims. (Cl. 12B-119) This invention relates generally tocarburetors for internal combustion engines and more particularly to means for controlling the air inlet or chokevalve thereof.

Internal combustion engines which burn a mixture of liquid fuel and airrequire a rich mixture for starting since the liquid will not vaporize as quickly when the engine is cold as when it is hot and therefore a greater proportion of fuel must be supplied in order to obtain the desired combustible charge. After the engine has started the proportion of liquid fuel to air must be decreased or the mixture will become too rich, resulting in irregular operation of the engine and a waste of fuel. The proportion of liquid fuel to air should be further decreased as the engine is progressively warmed up.

Means for thus automatically controlling Vthe choke valve of carburetors are well known and generally include an unbalanced choke valve openable by air flow through the induction passage in which it i-s located, and this choke valve is controlled by a temperature responsive device such as a thermostat which when cold is adapted to close said valve and to at least permit the valve to open gradually as the, temperature of the thermostatv rises with the operation of thev engine. Suchl automatic choke valve control means also usually includes a suction piston responsive to suction posterior to the thrpttle valve and arranged to urge the choke valve open against the closing force of the thermostat. However, diiculty is often encountered with such an automatic control arrangement when the engine is started cold andthe thermostat has not warmed up sufficiently to reduce the choke valve closing force thereof. Under such conditions of engine operation, the valve closing force of the thermostat is such that the choke `valve unduly restricts the entrance of air into the induction passage as the engine idles and the result is likely to be an abnormally rich mixture which overloads the engine as well as wastes fuel. It is to be noted that this condition is not satisfactorily relieved by the vacuum piston arrangement nor by a vspring closed poppet valve in the choke valve as is sometimes provided.

This automatic chokev arrangement also has another fault which may occur during periods of cold engine operation. That is, when the thermostat is set to properly close the choke valve so as to provide a sufficiently 'rich mixture for starting said engine, and undue enrichment of the fuel mixture is likely to occur when the throttle is suddenly and substantially opened i (but not to a position to operate the commonly used deooding mechanism) for acceleration of the engine, due to the sudden decrease of suction in the induction passage posterior to the throttle valve which therefore has little force for opening the unbalanced choke valve and greatly reduces the effect of the suction piston so that the thermostat closes or substantially closes the choke valve and insufficient air is admitted past it to provide a, fuel mixture of suitable proportions for proper combustion in the cylinders of the relatively cold engine. If the thermostat is adjusted to reduce the force closing the choker valve when the engine is cold so that the mixture is not unduly enriched when the throttle valve is thus"`opened, the thermostat exerts insufficient forces on the choke valve to provide a sufficiently rich mixture for starting the cold engine.

It is therefore an important object of thev present invention to provide means for correcting the above mentioned faults.

It is another'object of the invention to provide a choke valve control of this character wherein vacuum piston is not required.

Still another object is to provide a device of this character including both automatic means and manual means for controlling the choke valve.

A still further object of the invention is to provide a device of this character wherein a temperature responsive device yis adapted to control the choke valve throughout a range of movement between a predetermined partly open position and the fully open position.

It is also desirable under some operating conditions to have the choke valve of the carburetor under full manual control and it is therefore a further object of the invention to so construct and arrange the manual control that it is adapted to control the choke valve throughout its range of movement, overriding the valve closing force of the thermostat if necessary.

Other objects of the invention are to provide effective and reliable choke valve control means of relatively simple construction and operation and of relatively low manufacturing cost.

Still other, objects and advantages of the inventionwill become apparent from the following description taken in connection with the accompanying drawing, in which:

Figure l is a side view of a carburetor, partly in section, embodying the invention; and

Figure 2 is an end view of the carburetor showing the interior of the thermostat chamber.

Referring more particularly to the drawings the carburetor may be of any well known construction and as shown comprises an air inlet section I8, a main body section |2, and a throttle body section I4, the latter having a flange I8 for mounting the carburetor on the engine intake manifold which, as shown, includes a hot spot I8. An inductionl passage extends throughv the car-l buretor and includes an air entrance 28 controlled by the usual unbalanced choke valve 22 mounted on a choke shaft 24. Said choke valve may include, if desired, a relief or pODDet valve 28 of known construction and arrangement which is normally urged closed by a spring 28. The induction passage further includes a large venturi 38, a small venturi 32 and a mixture outlet passage 84 controlled by the usual throttle valve 88 mounted on a throttle shaft 38 on one end of which is attached a throttle lever 48 connected with any well known accelerator mechanism by a rod 42. The throttle valve is normally urged toward closed position by a spring which in the drawing is shown diagrammatically at 44. Fuel is supplied from a float chamber 48 having the usual float mechanism 48 for controlling the fuel level, the fuel being delivered into the induction passage by a fuel nozzle 88 discharging into the small venturi, said nozzle having the usual air bleed 82.

The carburetor also includes the usual idling system shown as including an idling tube 84 through which fuel passes to the idling passages 88 and 58 and discharges through portsI 88, adjacent the edge of the throttle valve when closed. The carburetor may also include an economizer system for enriching the fuel mixture under certain operating conditions4 and an acceleration pump. Neither the economizer system nor the acceleration pump are shown,`but may be of any of the well known types. such, for example as are shown in the patent to Cole No. 2,141,594.

The carburetor may further include ,the usual fast idle mechanism which in the drawings is shown as comprising a fast idle cam 82 pivotally mounted on a stud 84 fixed in the throttle body section and having a stepped cam surface 88 adapted to be engaged by an adjustable stop screw 68 in anl arm 18 of the throttle lever. Cam 82 is connected by a link 12 to a lever 14 attached to one end of the choke valve shaft 24 and is adapted to provide an increase throttle valve opening when the choke valve is in a substantially closed position.

If desired, a lost motion connection between the cam 82 and the choke valve may be provided, said connection including a slot 83 in the cam in which a laterally turned end portion 85 of link 12 is re, ceived and a spring 81 causes said laterally turned end portion 85 to be normally disposed in the upper end of slot 88 as viewed in Figure 1. ,By this arrangement a limited opening of the choke valve is permitted, even though the cam 82 may be restrained by the throttle stop screw 88.

'I'he mechanism for controlling the choke valve" in accordance with engine temperature includes a thermostat 18 disposed within a cover 18 attachedto the hot spot I8 of the manifold by screws 18 thus providing a heat chamber 88 for ythe thermostat which is shown as a lbimetal U- shaped strip` although it may be in the form of a coil or the like. The thermostat 18 is mounted horizontally in the chamber 88 with the lower 4 provided adjacent the closed end of the thermostat in which' the lower horizontal arm thereof is received, said member 82 being rotatable to permit normal movement of said thermostat as it `changes shape under variations of temperature.

and it is to be noted that the slot in the member 82 may be enlarged at each end to insure free sliding movement of the thermostat therein. An adjustable stop screw 84 is provided in the upper wall of the cover 18, said screw 84 being adapted to limit the upward movement of the free end of the upper arm of the thermostat which' is adapted to move upwardly when cooling and downwardly as it ls heated, as indicated by the respective arrows C and H, and said end is pro-y vided with an eye 88 which pivotally receives therein a laterally turned end portion 88 of a rod 88 which extends upwardly of the thermostat through an opening 82 in the upper wall of the cover 18. The upper end of rod 88 is screwed into the lower end of a sleeve 88 said sleeve being adjustable on the rod and is held in adjusted position by a lock nut 81. Opposite end of sleeve 88 is provided with a longitudinal bore in which is slidably received the lower end of a rod 88, the other end of said rod being pivotally connected to lever 14.

The means for manually controlling the choke valve may be a Bowden wire arrangement which includes a cylindrical plunger |88 having a knob I8 I., said plunger being slidably received in a suitable guide |82 ilxed in the dash or instrument panel |84 of an automobile or the like by means of a nut |88. The plunger is provided with a wire |88 slidable in the usual flexible sheath |88 attached at one end to said guide |82. The wire |88 is slidably received in a lug ||8 pivotally mounted on a lever I|2 fixed to the choke shaft 24.

A latch arrangement is provided for the plunger which includes a circumferential groove ||4 intermediate the ends thereof which is adapted to -be engaged by a ball ||8 received in a recess |'|8 of the guide |82 and urged inwardly by a spring |28. The free end of the wire |88 is provided ,with anv enlarged head |22 and a lug |24 of any suitable character is attached to said wire by a screw |28, said lug |24 being on the opposite side of lug ||8 with regard to the enlarged head The operation of the device is as follows:

Assuming that the engine is cold, that the plunger is in the intermediate position shown in Figure l, and that the thermostat is in the position shown in Figure 2; the chokevalve will then be positioned substantially as shown in Figure l. It is to be noted that the stop 84 limits the upward movement of the upper arm of the thermostat so that said thermostat cannot completely close the choke valve. However, as it is usually necessary to completely close said choke valve when the engine is cranked cold said valve is positively closed by pulling the plunger |88 outwardly, the head |22 of the wire |88 then engaging the lug ||8 on lever ||2 to move the choke valve to the closed position.

It will be understood that when the choke valve ls fully closed the end of rod 88 in the bore of sleeve 86 is partially pulled from said sleeve so that the position of the thermostat is not disturbed. However, the length of the sleeve 88 is such that the rod 88 is not disengaged therefrom.

vIn the present embodiment of the invention, as shown, poppet valve 28 will admit a limited amount of airv past the closed choke valve when the engine is being cranked on a little more air as soon as said engine begins to fire. I! desired, the lost motion connection between the fast idle cam 62 and the choke valve may be used instead of the poppet valve 26 or both arrangements may be used together.

As soon as the engine starts to operate under its own power the plunger |00 is pushed inwardly to the intermediate position whereat the ball II6 engages the groove I i4. With the plunger in this position the choke valve is opened by gravity and suction or air iiow in vthe, induction passage to the position shown in Figure 1, at which time the thermostat becomes effective to yieldingly resist further opening movement of the choke valve, Il it is desired to permit the thermostat to control further opening of the choke valve in accordance with engine temperature the plunger is left in said intermediate position, the spacing of the head |22 relative to the lug H0 on lever H2 being such that the choke valve is permitted to fully open without interference by the manual control mechanism. Under such conditions the force of the thermostat opposing opening of the choke valve is such that a sudden increase in suction in the induction passage, due to suddenly opening the throttle valve, will not materially change the position of the choke valve. Thus, undue leaning of the fuel mixture is prevented when the engine is suddenly accelerated.` Loading of the engine while idling during the initial portion of the warming up period of the engine is also prevented by this arrangement due to the fact that the choke valve is maintained in a suitable partially open position whereat it permits the necessary quantity of air into the induction passage for the required mixture.

It is to be noted however that a limited opening of the choke valve beyond the normal thermostat positioning thereof may sometimes be desirable, such opening being permitted by the overrunning connection between link 12 and cam 62. Should the engine become flooded when it is cold and the thermostat is positioned (as shown in Figure 2 for example) so as to at least partly close the choke valve, positive and substantially full opening of the'choke valve, to deflood the engine, may be effected by moving the plunger Wil' inwardly to its limit of movement. The lug |24 then engages the lug lll) of the lever H2 which is thereby moved clockwise, as viewed in Figure 1. Thus the choke valve may be opened in opposition tothe valve closing. force of the thermostat so that large quantities of air may be drawn into the engine to clean out excessive quantities of fuel, said manual control means overriding the thermostatic control of the choke valve.

While one embodiment of the invention has 6 way connection between the temperature responsive means and choke valve whereby the latter may be fully closed without disturbing the position of the temperature responsive means; and manual means adapted to control the choke valve irrespective of the force exerted thereon by the temperature responsive means.

2. In a carburetor for-'an internal combustion engine having an engine heated hot spot: an air inlet for said carburetor; an unbalanced choke valve controlling said inlet; a chamber adjacent the hot spot and adapted to be heated thereby, a U-shaped thermostat located in the chamber; means for Vadjusting the tension of the thermostat; a one-way connection between the thermostat and the choke valve; an adjustable stop member adapted toy limit the action of the thermostat whereby same is prevented from fully closing the choke valve; said one-way connection permitting the choke valve to be fully closed without altering the position of the thermostat; and manual means adapted to control the choke valve throughout its range of movement and to hold said choke valve fully open when at one limit of movement and to hold said valve fully closed when at the other limit of movement, said manual means, also being adapted to be so positioned as to be inoperative relative to` control of the choke valve.

3. In a carburetor: an induction passage having an air inlet; a choke valve in said inlet adapted to be opened by suction; a U-shaped thermostat having the arms thereof disposed substantially horizontally; a one-way connection between onearm of said thermostat and the choke valve; means for vertically adjusting the other arm of said thermostat; and means for limiting the valve closing movement of the arm connected with the choke valve to permit the thermostat from fully closing said valve.

4. In a carburetor: an induction passage having an air inlet; an unbalanced choke valve controlling said inlet; Va U-shaped thermostat; means for adjusting the tension of said thermostat; a one-way connection between the thermostat and the choke valv an adjustable stop member adapted to limit the action of the thermostat whereby the same is prevented from fully closing the choke valve', said one-way connection permitting the choke valve to be fully closed without altering the position of the thermostat; and

been illustrated and described it will be apparent to those skilled in the art that various-changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention, or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment. y

I claim:

1. In an internal combustion engine carbureto having an induction passage: an unbalanced choke valve in said passage; temperature responsive means for controlling the opening of the choke valve, said temperature responsive means being located adjacent a source of engine heat; means limiting valve closing movement of the temperature responsive means for preventing same from fully closing the choke valve; a onepivoted guide means adapted to support one arm of the thermostat.

5. In a carburetor having a choke valve: a substantially U-shaped thermostat; means connecting one arm of the thermostat with the choke valve; means for securing the other arm of the thermostat to a xed support; and a pivoted support and guide member for said thermostat having a slot within which one arm of the thermostat is movably received.

6. In a carburetor having an induction passage with an air inlet: a choke valve in said air inlet; a substantially U-shaped thermostat; a connection between one arm of 'the thermostat and the choke valve; and a pivotedadjustmerltdevice including an eccentric member, the other arm of said thermostat having a portion turned about the eccentric member, said member being rotatable within said turned portion of the thermostat.

'7. In a carburetor: an induction passage having an air inlet; and unbalanced choke valve controlling said inlet and urged toward open position by air flow in said induction passage; a

tween the thermostat and the choke valve comprising a rod having one end connected with the choke valve, a second rod connected with the thermostat and a sleeve threadably connected with one rod and having a longitudinal bore in vwhich the other rod is siidably received, the bored -portion of the sleeve being of suiiicient length to prevent the'rod therein from becoming disconnected therewith under all operating conditions; an adjustable stop member adapted to limit the action of the thermostat whereby the same is prevented from fully closing the choke valve; and manual means for fully closing the choke valve; said one-way connection permitting the choke valve to be fully closed without altering the position of the thermostat. ALBERT H. WINKLER.

REFERENCES CITED The following references are of record in the 5 le of this patent:

UNITED STATES PATENTS Number Name Date Williams Apr. 3, 1928 Heitger Sept. 1, 1931 Heitger j. Oct. 11, 1932 Ericson *June 27, 1933 Heitger June 11, 1935 Stanton Apr. 13, 1937 Ericson Sept. 21, 1937 Jorgensen Apr. 9, 1940 Hunt July 28, 1938 -Hodges Apr. 25, 1922

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