US2236595A - Carburetor - Google Patents

Description

J. R. FISH CARBURETOR April" 1', 1941.

Filed July 31, 193 4 Sheets-Sheet 1 m E M BY D ATTORNE J. R. FISH 'CARBURETOR 4 Sheets-Sheet 4 Filed July 31, 1935 m WM ?atented Apr. 1, 1941 UNITED STATES v PATENT OFFICE 2.236.595 cmonn'roa John Robert Fish, West Springfield, Mass.

Application .1111, 31, 193:, serial No. 682,980

9 Claims. (01. 261-34) 7 y connection of the several parts and their manner This invention relates to carburetors, particularly such as are adapted for use on the internal combustion motors femployed on automobiles. One object of the invention is to produce a carburetor which will accommodate itself to the varying mixture requirements automatically and without the use of mechanically varying nomles or valves. Another object is to improve the distribution and atomization of the fuel in the air stream. Another object is to provide a carburetor which will produce a richer mixture when the throttle is opened to cause motor acceleration, and which will cause this enrichment of the mixture to persist for'a period sufllcient to permit full acceleration of the motor. Another object istoprovide a carburetor which will automatically reduce the fuel flow when the throttle is shifted to cause deceleration of the motor. Another object is to provide a device for controlling the mixture for starting a cold motor in which eflicient starting conditions will be main: tained and in which there ,will be no danger of flooding the motor in case the starting control is inadvertentlyvleft in operation. Anotherobject is to provide a carburetor having an improved idling system. Additional objects will appear from the following description and claims.

Referring to the drawings,

Fig. 1 is a perspective view of the float chamber of the carburetor, this chamber being shown as removed from its normal position, and this view together with Figs. 2 and 3, forming a composite view of the entire carburetor;

Fig. 2 is a perspective view of a plate dividing the float chamber from the main part of the carburetor;

Fig. 3 is a perspective view'of the main part of the carburetor with the float chamber-and the dividing plate removed;

Fig. 4 is a top plan view of the carburetor;

Fig. 5 is a side view of the carburetor, looking from the starting control side;

Fig. 6 is a side view of the carburetor, looking from the gasoline admission side;

Fig. 7 is a view of the float chamber end of the carburetor;

Fig. 8 is a detail of the throttle valve;

of functioning. t

For simplicity the specific mechanism constituting the preferred embodiment of the inventionwill be described first with little reference to the way in which the several mechanisms cooperate. It will be understood, however, that the detailed forms of these parts may be varied without departing from the invention as set forth in the-claims, and that the description of mechanical, structure with considerable minuteness is for purposes of clarity and not by way of limitation. The carburetor is shown as built the body is flattened off at 22 to receive a separating plate 23 which forms a side wall of a gasoline chamber 24, the purpose of which will be described below, Upon the other side of the plate is.a casting 25 hollowed out to form a float chamber 26. The casting 25, the plate 26, and

- the body 20 are held together by screws 21, the j heads of which are preferably groundin place rests loosely upon the float, and is raised and of th ca i 25, and has a nut-shaped top 36- Fig. 9 is a diagrammatic detail of mechanism used mainly in the starting operation, the parts being shown in diflerent positions than in Fig. 10 is a section through the carburetor on a lowered by the vertical movement of the latter so as .to regulate the rate of flow of gasoline into the float chamber and maintain the level therein. The nozzle as is screwed into the top by which it may be turned. A sleeve 3! surrounds the nozzle. seating at its bottom on a suitable gasket placed on the casting, and engaged at-its top by a conical flange 38 on the nozzle which may seat-with a ground joint. A' cylindrical screen 39 is placed in the space between the sleeve and the nozzle if desired, so as to filter the incoming gasoline. Gasoline is led from the fuel pump or tank into the sleeve bf; a pipe 60, passes through the screen, and enters the bore 33 through a plurality of holes M situated above'the constricted portion. This valve mechanism operates. in general like the usual float valve, but has the advantage of being removable without disassembling the carburetor. Regulation of the level of gasoline within the float chamber is obtained by changing the thickness or number of gaskets underneath the sleeve 31.

A hole l5 is formed in the plate 23 to permit gasoline to pass from the float chamber into a passage 46 formed in the body portion and communicating at 41 with the chamber 24. The opening 41 is covered by a feather valve or spring plate 48 which functions as a check valve, permitting flow out of the float chamber but preventing flow in the opposite direction. A second passageway 49 between the float chamber and the chamber 24 is provided in the plate 23 for a purpose to be described later.

The body 20 is formed with an air passage 50 here shown as centrally contracted as best shown in Fig. 1-1 to form a constriction or venturi. Extending transversely through this constriction is a shaft journaled at on end in the body portion 20 and at the other end in a removable gland 52 held in place as by screws 53. The central portion of this shaft is formed with a throttle 54 here shown as having the general form of a double wedge placed between flanges 65 running in circular recesses in the wall of the air passage, although its shape may be varied in accordance with the shape of the air passage. A fuelpassage 56 runs through the center of the shaft. and is connected by holes 51 with one of the surfaces of the throttle. The average automobile engin is set. on somewhat of a slant, and for this reason it is sometimes preferable to arrange the holes 51 on a slanting line, as shown in Fig. 8 and Fig. 10, so that they will lie on a level line when the carburetor is in position. The hydrostatic head at the opening of each of the holes is by this means made equal. In order to prevent leakage between the air passage 50 and the fuel chamber 24, a groove 58 is preferably formed around the shaft 5| connected to the atmospheric side of the air passage 50 by a duct 59. While it is not essential, and in many installations will not be used, a needle valve 60 having an adjusting head 6| and passing through a packing gland 62 may be threaded into the passage 56 so as to bear adjacent a reduced portion thereof, and thus regulatethe supply of fuel to the holes 51. The position of the throttle can be adjusted by means of the usual control arm 63, a compression spring 64 placed between this arm and the gland 52 serving to hold the fuel feeding arm 66, described below, against the inner surface of the fuel chamber 24, sealing it against leakage.

Over a portion of the shaft 5I at its end remote from the throttle arm is fitted the cylindrical head 65 ofa fuel feeding. arm 66, held in place as by a nut 61. A Passage 68 extending I longitudinally through the arm connects at its' upper end with the passage 56 and at its lower end communicates through a removable nozzle 69 with the side of the arm adjacent the feather valve 48. Communication is thus established between the holes in the throttle and the fuel in the chamber 24. An additional passage in the arm preferably communicates with the passage 68 through a series of small holes 1|, and at its upp r end is joined by a passage 12 (Fig. 14) with an arcuate groove 13 formed in the surface of the cylindrical head 65. This passage 12 is joined by a cross groove 14 with a second arcuate groove of greater length. A passage 16 in the body mates with the long groove15 throughout the swinging movement of the fuel feeding arm, this passage communicating through a jet 11 and a hole 18 in the plate 23 with an air chamber 19 formed in the casting 25. A passage 80 leading from this air chamber through a hole 8| in the plate 29 is connected to the atmosphere through a jet 92. Air is admitted to the shorter groove 14 through a passage 83 connected to the chamber 19 through a jet 94-. A passage 85 joins the chamber 19 to the float chamber 26. Th float chamber and the air chamber are thus maintained under substantially atmospheric pressure. The supply of air to the arm passage 10 varies in different positions of the throttle, air being received from both the passages 16 and 89 until the throttle is about half way open, when the passage 93 connecting with the short groove is cut off. The purpose of this construction will be described below. An alternative way of enriching the mixture as the throttle is opened is to provide one or more grooves 96 in the side of the chamber 24, with which a hole 81 in the arm 66 is adapted to register in certain positions of the throttle. The hole 81 communicates with the passage 68 to provide an additional fuel orifice. By varying the length and location of the grooves 86 the fuel flow may be adjusted as may be required at different throttle openings.

The section of the device now to be described relates mainly to the functioning of the carburetor in starting the motor, although it has a modified action after the motor is running. A

well formed in the body 20 and closed at one side by the plate 23 is closed at its top by a gland 9|, furnishing bearing for a plunger 92. A flange 93 on the reduced lower end of this plunger serves as an abutment for a spring 94 by which the plunger is normally held in an elevated position. The plunger is not long enough stricted portion of the main air passage at a point just below the rear side of the throttle when in closed position, as shown in Fig. 11.

e (For convenience the side of the throttle not containing the fuel feeding holes 51 will be referred to as the rear side.) The second set comprises a series of holes I02 extending radially through an enlargement I03 of theplunger and terminating in longitudinal notches I04. The enlargement I03 is doubly'frustoconical in form and is adapted to rest against the beveled lower end of the gland 9| when the device is in position for normal engine running, and to bear against the beveled upper side of a flange I05 when the plunger is depressed into the motor starting position. Flange I05 does not reach to the plunger 92, an air space being left by which, when the plunger is elevated, the upper part of the chamber is communicating through the notches I04 and thus into the upper part of the passage 95 and hole 96. Flange I05 does, however, extend inwardly beyond the notches I04, so that when the plunger is depressed these notches are cut off from communication with the chamber 90. The chamber 90 is fed with gasoline by a passage I06 leading from the float chamber and entering the chamber 90 by a removable jet I01. By changing this nozzle the rate of flow of gasoline into the chamber may be controlled. An air passage I08, the flow through which may be controlled by a needle the plunger may be controlled by any-suitable device, either thermostatically or from the dash.

In the case shown, a slide I'I0'is mounted in ways formed in the carburetor body. and bears a camshaped end II I which acts 'to depress the plunger when the slide is moved. A clamp II! (Fig. 4) is also mounted on the body to receive the usual Bowden wire tube, the wire of which is connected to the slide so that it may be operated from a distance.

The last mechanical assembly to be described has a desirable additional function in accelerating the engine when the throttle is quickly opened, and may be omitted if not needed for particular installations. A chamber I20, provided with a well I2I, is formed in the carburetor body. and is joined by a duct I22 to a jet I23 entering the air passage 50 at a point just above the front side of the throttle when the latter is closed. Dipping into the well I 2|, although stopping clear of its bottom, is a tubular member I20 having a head I25 rotatable within a hole in the body 20. A plurality of holes I20 of different sizes selectively connect the interior of the tube to a duct I21 connected to the'gasoline-chamber 20 at I20. The head I25 is provided with slots I29 into which "a spring detent I30 ilts so that the ,member I20 may be held with any desired one of the holes I28 in register with the duct .121. The tubular member thus actsas an adjustable nozzle I3! (Fig. 16) by which the inflow o't gasoline from the chamber 20 is regulated. Substantially atmospheric pressure is maintained in the upper portion of the chamber I20 by a duct I02 leading to the chamber 19. -It will be apparent that if the fuel arm be moved towards the feather valve 08 (as it'is when the throttie'is suddenly opened), the feather valve will close, and gasoline will flow through the duct I21 into 'ber. It is also preferable to have the duct I2? connected directly witha nozzle its in the air passage wall (Figs. 10 and 16) by a'duct I04 for a purpose to appear. Access. to the replaceable jet I23 may be: had through a removable plug I35 in the outer wall of the chamber I20.

Consideration of the operation of the carburetor will be begun on the'assumption that the motor is to be started when cold. The action of the present carburetor is fundamentally different from that of the usual carburetor choke control. For the starting operation the plunger 92 is depressed, bringing the enlargement I03 against the flange I and cutting off direct communication between the top of chamber 90 and the notches I04. The throttle is nearly or entirely closed, bringing the 'hole 51 above the fuel line I60 and thereby cutting off flow of gas through them. The nozzle I0! is, however, situated below the throttle, in the region of low pressure created by the motor as it isturned over. The differential pressure acts through the duct I0 0, causing gasoline to pass through the plunger 92 and the lateral hole 96. It will be remembered that the upper part of chamber 90 is kept at substantially atmospheric pressure by the duct I00. A slug of raw gasoline will be moved through the duct I00, mingling with what air passes the throttle. This condition will be only temporary, since the hole 90 will pass gaso-. line faster than it is admitted tothe chamber through the nozzle I01. This causes the fuel level in the chamber to fall until it reaches the bottom end of the. plunger. The quantity of fuel passed by this means will be just sufficient for the first few explosions, serving to get the motor started. After this air enters the hollow plunger along .with the gasoline, reducing the richness of the mixture and automatically preventing flooding.

After the motor has warmed up the plunger is released, bringing its enlarged portion against the bottom of the gland 9|. Under this condition the air from duct I08 can pass the notches I06] of the mixture passing through nozzle IN is further reduced, and the gasoline still more fully mingled with the air. By reducing the effective fuel feeding pressure by this means it is possible the holes.

to make hole 86 larger than would otherwise be the case, avoiding the danger of plugging. As the throttle is opened the amount of gasoline entering the air passage 50 through the nozzle MI is reduced so that under normal running conditions it is negligible. While the motor is idling, however, the chamber 90 supplies most of the mixture required. The amount of air reaching the chamber, and therefore the'richness of the mixture leaving it, is regulated by the needle valve I09.

If the throttle is partly opened, as it is in medium speed running conditions, a different balance of operations exists. The constricted portion of the carburetor throat 50 is shaped diiferently at. the two sides of the throttle, the

front side (the side where theholes 51 are located) being cut away more than-the rear side of the throat, which fits the edge of the .throttle closely until the latter has been opened some little distance. Under moderate throttle open- I ings the air can be treated as if passing the front throttle edge only. Instead of the holes 51 being above the gasoline level I40, as they were when the throttle was substantially closed, these holes are brought to or below that level. This causes the gasoline to discharge through the holes and to flow down the face of the throttle where it mingles with the incoming air.

The effect of gravity is added to by the differential pressure existing between the low pressure at the Venturi throat and the substantially atmospheric pressure existing in the float and fuel chambers. As the throttle is more fully opened the holes 51 descend further and further into the constricted portion of theventuri, so that this difi'erentialefiect is increased both by-the change in position of the holes and by the increase in the differential pressure resulting from increased air flow, and at the same time the gravity effect is increased by the lowering of The quality of the mixture can be controlled by the addition of the air which flows down the back side of the throttle to that which comes down the front side, both sides of the throttle passing air after the throttle has opened a predetermined amount, which can be regulated by the relative shapes given to the throttie and to the restricted part of the air passage 50. The air passing down the rear side of the throttle acts both to lean the mixture directly and to satisfy some of the suction effect of. the

veconomy mixture to a power mixture. "respect the action differs from the usual accelmotor so that the differential fuel feeding pressure at the holes 51 is reduced.

The gasoline reaching the throttle through the passage 56 is mixed with air from the air duct ll in the fuel arm, if this duct is employed. It will be recalled that this duct is coupled to the fuel passage I by holes II, and is joined to the air ducts 16 and 83 by grooves 13 and I! in the cylarly to the needle valve Ill. or they may be replaceable screws having fixed holes. In its sec- 1 ond aspect, the air entering the fuel duct through passage ll serves to emulsify the gasoline, malring it lighter and assisting in its vaporization.

If the throttle be suddenly opened, as when it is desired to cause sudden acceleration of the motor,.additional effects come into play. It will be observed that an opening movement of the throttle causes' the fuel arm to move toward the feather valve 0. The valve is thereby closed, and a slug of the trapped gasoline will be forced up the passage 68 and out through the fuel openings in the throttle, thus richening the mixture and providing for wetting of the manifold walls as required for the added power called for from the motor. Instead of using an additional nozzle as in the usual accelerating pump, the gasoline is by this means driven out the usual fuel openings with a velocity dependent upon the speed with which the throttle isppened, and with no appreciable time lag after the opening of the throttle. The main fuel feeding system is instantly at full discharge. At the same time gasoline is forced by the fuel arm up the duct I21 into the chamber I" in an amount correspond- ,ing to the degree to which the throttle is opened and by the size of the aperture in the nozzle Iii. The gasoline from thischamber discharg s into the air stream through the nozzle, producing an enrichening of the mixture throughout a period normally suflcient to permit the motor to pick up to the speed desired, and acts as a device aiding the transition from the normal eration pump, which is operative only so long as the throttle is being opened. The lengthof this period is regulable by the amount of gasoline put into the chamber III. controlled by the size of the nozzle l3! and by the size of a bypass Ill (Figs. 2 and 16) to the float chamber. The added richness of the mixture during the transition period is controlled by the sizes of the nozzle m and the vent In. In case the throttle is closed before the gasoline in chamber if. ,is exhausted. the movement of arm it away from opening I28 causes a reverse fiow of gasolin in duct I21, siphoning the gas out of the chamber I and preventing the functioning of this device after the reason for calling it into action hasgone. A further reduction in the richness ofthe mixture during sudden closure of the throttle is accomplished by a tendency of the asoline to be drawn back through duct Cl as the 03 the wasteful flow of fuel due to momentum acquired during high speed operation. If it is desired to secure more initial richening of the mixture, or wetting of the manifold walls, than can be accomplished through the throttle openings, the direct connection I from the duct III to nozzle ill may be used. This is effective only during the filling of the chamber I20 and does not afiect the continued action of the latter.

During the running of the motor with small throttle openings, the rear side of the throttle does not pass any substantial amount of air. An eddying of the mixture passing the front side of the throttle. occurs below the throttle which assists in the adequate mixing of the gasoline and air. This effect is reduced as the rear side of the throttle passes more and more air during further opening, so that the resistance ofiered by the eddy currents is reduced. At the same time the volume of air fiow through the venturi increases, the openings 51 are lowered more and more into the low pressure zone of the venturi, and the differential pressure between this low pressure zone and the atmosphere increases because of the added velocity at high speeds. If

the motor is running slowly at full throttle, the,

properly adjusted-for a particular engine the carburetor will give much better economy than is possible with existing commercial carburetors, and at the same time the richer power mixture will be produced whenever the motor load warrants it. It will be observed that this is accomplished automatically without the use of nozzles which are varied in setting during the operation of the motor. When once adjusted, all openings are constant, but due to balancing of pressures and change in the positionof holes I1, the varying mixtures required are produced automatically. r

' It will be observed that the air space above the fuel in the float chamber is connected to the atmosphere through the passage I! and a nonle II. Air supplied to the various parts through passages Ill, I32, It, and 83 is obtained through this same chamber, and .the pressure of air in the heat chamber is thus a reflection of the engine manifold pressure modified by the effect of the nozzle 82. As the load on the engine drops the manifold pressure will be reduced, causing a decreased pressure of air in the fioat chamber. This operates to decrease the richness of the mixture when the motor is not under load. irrespective of throttle position, and causes an automatic change in the richness of the mixture as the power requirements of the motor fiuctuate. The carburetor is also through this means made substantially independent of changes in atmospheric pressure due for example to altitude.

I claim:

1. A carburetor having a constricted air passage, a throttle located in the constricted portion of the passage and provided with fuel distributing openings located in its surface, a segmental fuel chamber, an arm secured to the throttle and movable arcuately in saidchamber about the axis of the throttle, a passage through said arm connecting'with said fuel openings in the throttle and opening into said chamber, and means for supplying said chamber with fuel.

arm I is moved away from the valve ll, cutting 2. A carburetor having a constricted air passage, a throttle located in the constricted portion chamber and that side of the fuel chamber tosage through said arm connecting with the fuel to the S n pa e- -float chamber, a fuel chamber, a throttle in the "mixing passage, and a well having a gravity conpassage,- and an additional amount will be forced 81? am in Said ber connected to the in the air conduit, the conduit and throttle being the arm moves n pening the throttle, whereby therewith, a connection between the float chem 50 e for a substantial time after openin of h mel chamber towards whi h th 8m,mves member forming a main fuel and air passage and throttle. tubular member carried on said shaft in said fuel intlie air eonduit,'-the conduit and throttle being to said passageway, meaus'forming a supplemenin the air passage where the air passes the throttle, a float chamber, a segmental fuel chamof the passage and provided with fuel distributwards which the arm moves on opening the ing means, a fuel chamber, an arm secured to the throttle, a check valve interposed in said connec-"' throttle and movable in said chamber, a check tion and operating-to prevent flow from the fuel valve opening into said chamber on the side to 5 chamber 'to the float chamber, a fuel passagewhich the arm moves as the throttle is opened, through the arm opening at one end into that side fuel metering means opening from the arm into of the fuel chamber towards which the arm moves the chamber on the side of the arm adjacent the on opening the throttle, and opening at the other check valve, a'duct connecting said means with end onto the surface of the throttle, whereby fuel the openings in the throttle, and means for sup- 10 may pass dur n n rmal p ration throu h th plying said chamber with fuel. arm to the main air conduit, and an additional 3. A carburetor havin a constricted ahpa amount will be forced through the arm into the sage, a throttle located in the constricted portion conduit n S n op n n f he thro l a of the passage, and provided with fuel openings met a r inlet opening into the float chamber. in its surface, a fuel chamber, an arm secured to' a Second P 8 the arm con ec ed y h es the throttle and movable in said chamber, a paswith the first passage, and means f admitting openings in the throttle and opening into said 7. A carburetor comprising a main air conduit, chamber, means for admitting air to the passage & throttle in Said nduit, a constant level fuel in the arm whereby it .maymingle wit t supply chamber; afuel chamber connected therefuel therein, and means for supplying said ch to, an arm in said fuel chamber connected to her with fuel. I 1 the throttle for movement therewith, a main fuel 4, A rb r t comprising mixing passage connection between the fuel chamber and the mixing passage, an arm in the fuel chamber and 5 motion the mixing p e and connected to coupled to the th t fqrimovement t th the fuel chamber on the side thereof toward which connections between the float chamber and the the arm moves on penin the throttle, whereby fuel chamber on opposite sides of the arm, a check on opening e throttle rapidly a supernormai valve interposed in the connection on that side of ammlht of Will be l t into e mixin the fuel chamber towards which the arm moves on thmugh the mam fuel on by t e opening the throttle and operating to prevent flow movement the and a q ty f fuel will from the fuel chamber to the float chamber, and a also be forced into the well to nri h the mixture w passage through the arm opening at one end for a substantial time after opening of the into the fuel chamber on the side containing the throttlecheck valve, and opening at the other end into A carburetor 8 8 main n i the mlxing passage whereby fuel may pass d u-[ng a throttle 1!! said conduit, 8, constant level fuel operation through the arm to the mixing supply chamber, a fuel chamber connected theremmughv the am into the mixing passage onv v throttle for movement therewith, a main fuel sudden opening 1 t thmgflm 40 connection between the fuel chamber and the 5. A carburetor comprising a main air conduit 1 mixing p nd a well, having acre-V i! nadapted to be coupled to the intake manifold of motion t the mix n pa sa e and connected to a int r l b ti t a rotatable throttle the fuel chamber on the side thereof toward which relatively so shaped as to produce a constriction .on open n the le rap ly a pernormali intnenirp sn e where the air passes the throttle, amount of fuel w e elected into the mixing a heat chamber, a segmental fuel chamber, an p s e through the main f el c n n y h a fittin snugly i t m chamber and movement of the arm, and a quantity of fuel will nected to th thr ttl for ill ti 1 ,11 also be forced into the well to enrich the mixb and th fuel chamber on the side towards U throttle and whereby the well will be drained which the arm moves on opening the throttle, a and suhhollhal flflw of fuel h h he main check valve interposed in aid onn t and fuel connection will be brought about by a reoperating to r nt flow from th m chamber verse movement of the arm due to a rapid closing to the float chamber, and a'fuel passage through of the throttle. a p f, the arm opening at one'end into that side of the A e or having. i b atio a'bod:

opening thethrottlemndopening at the other end. fuel p y, chamber d c S p ge. 8 ontothe surface of. the throttle, whereby fuel throttle, a t rotetablir mounted n aid body may pom du in n l operation through t '60 member carrying said throttleand having one arm to the main air conduit and an'additi end thereof extending into said fuel chamber, amount will be forced through the arm into the means for plyin fuel o said mai passa e mixing passage on sudden opening of th comprising a passageway in said shaft, and a 6, A carburetor comprising a main air conduit chamber adapted to swing therewith and extendadapted to be coupled to the intake manifold of a ing downwardly into the fuel, means providing a an internal combustion motor, a rotatable throttle metering inlet port for limiting the flow of fuel relatively so shaped as to produce a constriction tal inlet port, a valve normally closing said supplemental inlet 31014:. and means for opening said valve when the throttle reaches a predetermined her, anarm fitting snugly in the fuel chamber point in its opening movement.

and connected to the throttle for oscillation coaxially therewith, a connection between the float JOHN ROBERT

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