US1872708A - Carburetor - Google Patents

Description

Aug. 23, 1932.

G. R. ERICSON CARBURETOR 7 as H 2.9 25 a 2 AT TOR/V5 Y- Patented Aug. 23, 1932 UNITED STATES 1 PATENT OFFICE GFDBGE-B, ER ICSON O1 IAPLEWOOD, 118501781, ABSIGNOB '10 GABTEBOARBUBETOB CORPORATION, OF ST. LOUIS, MISSOURI, A CORPORATION nmwana CABBUBE'IOB Application med April 27, 1828, Serial 110. 888,700. Renewed October 19, 1981.

This invention relates to carburetors for internal combustion engines and particularly to devices for maintaining a satisfactory fuel mixture ratio at all operating temperag'tures. This application discloses certain subject matter in common with co-pendin applications Number 446,899 filed Apri 24, 1930 and Number 573,418 filed November 6, 1931. Carburetors of the type in which the fuel is drawn into the air stream by suction have the disadvantage that the volume of air tends to decrease relative to the volume of 'fuel as the temperature increases. One cause for this is that a given volume of air at high is temperature contains less air by weight than the same volume at a lower temperature. Accordingly, a highe'reve city at the venturi is necessary to pass'a'gi "en amount of air at high temperatures than; aw.- A'nother cause is that the viscosity of th fueldecreasesas the temperature rises so t t more fuel will flow through a jet under a 'ven suction at highstemperatures than at low. The change in volume of the fuel upon an increase of up oifthe change in viscosity. The result is that a given suction in the intakemanifold will draw more fuel and less air at high tem-l periitures than at low, resulting in lean mix-p tures when the-motor is coldand'rich mix-- turcs when it is hotw- This condition .ac-

centu'ates' the well-known hard starting of motors-when cold, due to cor vaporization, and the necessity of adjusting the carburetor so rich that fuel is wasted when the motor is hot.

It is an object of-this invention to Hrovide means for mamtamm a substantia y contures. It is another ob'ect of the invention to provide a carburetor" aving' means to pre-.

vent a variation in the mixture from lean to rich as the motor heats up. I Further objects will appear from the following specification and the accompanying drawing, referring to 'which: I

Figure 1 shows a sectional side elevation of a carburetor embodying my invention.

Figure 2 shows an elevation of one form ofthermally operated controlmeans.

tem fature is not nearly suflicient to make.

stant fuel mixture ratio at varying tempera -Figure 3 is another view of the thermal control means shown in Figure 1 with the parts in a different position.

' The reference numeral 1 indicates the main body member of a carburetor having an air chamber 2 and an air inlet 3. The carburetor is attached to the en "ne by means of a member 4 having a suita 1e flan 5 for that pur pose. The main body mem r has a circular opening 6 which receives an annular extension 7 of the body member 4. A flange 8 and screws 9 serve as means to attach the member 4 to the main body member. Dowel pins 10 mafialso be provided, if desired.

0 member 4 has a passageway therethrough comprising an inwardly and upwardly tapering portion 11 extending fronif; I

from the carburetor. V

The main body member has an annular-surface 17 to' receive the upper ed of the fuel bowl 18. The lower part of the y member 1 is formed as an extension 19 and provided with a screw threaded'bore 20-, aaishd'wn-"eo A nut- 21is screwed'into the lowerfeiid of-ethe threaded bore 20 and serves to retainthe fuel' bowl. A p

comprising a primary mixingchamber is 1 way 22 is'formed the extension 19 and connects the air chamber 2' with the threaded bore 20. A'stand pipe 23 attached to the main member'- at the lower part of the chamber 2 by suitablescrew threads 24. An opening 25 connects the upper.

- part of the passageway 22 with the air chem ber. An annular member 26'. is fitted into the lower end of the stand pipe .llustf' above the annular member 26, a' port'fl reformed in the wall-of the stand pipe, and a'primary";

venturi or a in the bore of thestan p 1 port 27. A frusto-conica 'cho e neraber 29 1s slidably mounted on thestand pipe, yoke 30 mounted on a manually o b le shaft 31 is provided for moving the oke into the rtion- 28 is formed ipe 'ust above the throat of the main venturi 12 when desired. A main jet member 31a is threaded into the upper portion of the bore and extends up wardly through the passa way 22 and the 5 annular member 26 to a point near the throat of the primary venturi 28. The walls of the main jet are somewhat smaller than the inner bore of the annular member 26, as shown. Suitable bleed ports 32 may be drilled in the walls of the main jet 31 wherever desired. An upwardly extending bore 33 is formed in the an ed member 4 and terminates in a transverse re 34 at an edge of the throttle 15. An adjusting screw 35 havin an air bleed port 36 is threaded into the re 34, as shown. A spring 37 may be provided to frictionally maintain adjustment ofthe screw 35. A small tube 38 having a restricted portion 39 and an air bleed port 40 is fitted into the lower end of the bore 33. The lower end of the tube 38 is fitted into a bore 41 and the extension 19. The lower end of the bore 41 isenlarged at 42 to provide an annular recess around the end of the conduit 38, and a small port 43 is formed in the wall of the tube to communicate with the annular recess. The lower end of the bore 42 is closed by a screw 44. A transverse bore 45 is formed in the extension 19 and communicates with both the 30 annular recess 42 and the passageway 22. The outer end of the'bore 45 is closed by a plug 46. A threaded bore 47 is formed in the extension 19 to receive-ajet 48 having a calibrated passage 49 therethrough. The ssage 49 provides the sole communication ween the fuel bowl and the bore 20.

A thermostatic baflle member 50 is sup-- pgrted in proximity to the inletend of the re 49 by a member 51 which is rovided m with an eye to receive the threade portion of the jet 48 and which is held'firml against the side of the extension 19 thereby The thermostatic member 50 comprises a pair of flat stri s of metals' having different coefli- 45 cients 0 expansion, the strip of metal on the side next to the member 51 having a low coefiicient of expansion, and the other strip havingahigh coeflicient of expansion. These strips of metal are firmly attached to each 50 other and operate in a well-known manner to'bend toward the jet-as the temperature increases or away from it as the temperature decreases. The thermostat is attached to the member 51 by a rivet 52 and is ivoted on the 55 rivet so that it may be turn to one side,

as shown in Figure 2, forthe purpose of regulating the part of the jet which is controlled thermostatically, and also for the purpose of permitting ready access to the hexagonal 3 head of the screw threaded jet.

I The lower end of the thermostat- 50 is provided with a port or perforation 59 of smaller diameter than that of the bore 49. The size of the port 59 is so calibrated that when the temprature of maximum efliciency contact with t is reached and the member 50 contacts with the head of the jet 48, a sufiicient quantity of fuel will flow through the port to supply the needs of the motor, and a further heating up of the motor will cause no further reduction in the fuel supply. 7

It will be noted upon reference to the drawing that a substantial area of the member 50 is closely adjacent and arallel to the end of the jet member 48. en the member 50 is in contact with the end of jet 48, the space between these members forms a fuel passageway through which fuel may flow at a'fairly high speed.

According to the well-known laws of hydrodynamics, when the velocity of a fluid in motion is increased, its pressure is correspondingly decreased, so that a substantial suction is produced between the parallel adjacent areas of the members 48 and 50, such suction tending to move the member 50 into e member 48, thereby closing the additional fuel inlet in advance of the time when it would normally have been closed by the temperature alone.

It should be noted that the lowerin of pressure between the parallel surfaces 0 the members 50 and 48 is not entirely a result of the transmission of suction from the interior of the passageway 49. The flow is of course originally induced by suction transmitted through the passageway 49, but the resulting suction between arallel surfaces of the members 48 and 60 is actually greater than the suction per unit area in conduit 49. This may seem unreasonable at first thought, but the truth of the proposition may be clearly illustrated as follows:

Reverse the flow of fluid through the passage 49 by producing a pressure instead of a suction in the mixin conduit. There will be a resulting flow of uid between the parallel surfaces of the members 48 and 50, but, of course, in an opposite direction. The member 50 will now be drawn toward the member 48 by the suction existing between the parallel surfaces due to the fact that a fluid is flowing therebetween. The pressure which initiates the flow would normall expected to push the member 50 away rom the member 48, and since this does not occur, it is obvious that there is another force of greater ma itude than the pressure itself which may known fact that it is diflicult to blow a disk of aper off the end of a l.

readily illustrated by the wellt will be understood t at the only times at which the suction becomes great enough to move the member 50 a substantial distance 1' are when the engine is operatin at nearly full speed and power, or when t e choke 29 is closed so that the suction is concentrated on the parallel areas between the members 48 and 50. f

The minimum fuel supply may be regu- I the port 59 goes out of registration alto eththrough passages 33, et cetera, to p "40to100 R. P. R,

lated by turning the member 50 on the pivot, so that less than the full diameter of the port 59 will register with the bore 49. When desired, the member 50 may be adjusted so that er, and the side of the member 50 regu ated to uncover more or less of the bore 49 as desired.

It will be understood that the thermostat may be used without the port 59 and regulated so as never to entirely close the bore 49.

It will be understood that the main jet member 31a is provided with suitable calibrated passa ways 53 leading from the bore 20 to the main bore of the jet and to the pas- 1 ea eway 22.

uitable conventional means is provided for supplying fuel to the bowl 18 in which it is maintained at a substantial constant level -by the float 54. The fuel supply conduit and inlet valve being entirely conventional and forming no part of this invention are not shown.

The operation of the device is as follows:

The carburetor being attached to an internal combustion en 'ne, suction in the passageway 14 is pro uc'ed by operation of the engine. With the valve substantially at closed position, as shown, fuel is drawn up from the fuel bowl 18 through the passageways 49, 53, '46, 38, 33, and 34 into'the assageway 14 above the throttle. Air is led in at the port 40 and also at that'portion of the bore 34-below the edge of the throttle. A

comparatively small amount of mixture entering in this manner serves to operate the engine at idling speeds. It will be noted that suction is transmitted from the outlet side of the throttle through the port 34 and 49, and to the member 50, so that whether the throttle is in opened or partially open position, as for a roper idle adjustment, suction ma be trans erred to the member 50. This wil have more effect, of course when the available for operating the valve 50; otherwise, with the valve 29 in closed ition, too a mixture would be delivered after the engine starts to run under its own power and after the suction has been increased in that manner.

The change in the auction developed by the engine when it starts town under its own power is due to thefact that its' r c. The normal cranking internal combustion enfiiliieare usually from w e the normal idle speeds of the same engines are from 200 to 400 R. P. M., so that when an engine starts to run under its own power, there is an instant increase in the "suction. This makes it ry to supply a leaner mixture just after starting than durin cranking speeds. In fact, there are severa reasons for supplying a leaner mixture after the engine starts to run under its own power, but one of the most important is that the increase of suc-' tion causes the fuel to vaporize more readily, so that some vaporized fuel and less raw fuel is delivered. The connection from above the throttle to the thermo-suction valve 50 provides means for automatically switching the mixture ratio from rich to lean as soon as the engine starts to run underits own power (assumin the choke valve 29 is in closed position for ow temperature starting).

For hi h temperature starting, the valve 29 is not ly closed or not closed at all, and the suction from above the throttle is relieved to quitea substantial extent due to the fact that the nozzle 27 is exposed to atmospheric pressure, and under these conditions, the valve 50 would not be moved to closed position unless it has already been moved to that position by the temperature.

When the throttle 15 is opened, air is drawn through the inlet 3, the air chamber 2, the throat of the venturi 12, and the mixing chamber 13. A smaller uantity of air passes from the chamber 2 t ough the port 27 the primary venturi 28, and the stand pipe into the mixin chamber. When the engine is running at high speeds with the throttle valve nearly or full open air also passes. down through the bore 25 into the passagewa 22 and bleeds into the ports 32 in the we of the main jet. main and rimary venturis draws fuel through the res 49, 20, and 53, the amount of fuel drawn in by a given suction bein calibrated by the resistance to flow present by these bores. When the engine is being started cold, it is desirable to temporarily increase the ratio of fuel to air, and for this purpose the choke valve 29 is moved into the throat 12 of the venturi to fiartially or fully close the same, as desired. y this means, all the suction-in the intake manifold is transmitted to the venturi 28 and the idling tube, causing a strong suction on this and a resulting increase in the flow of fuel. This strong The suction at the m osition and thereby reed passageway around the standpipe 23 causes the suction to be increased to such a point that suflicient fuel will be drawn in fact, this partial closing of the fuel inlet permits the use of a more highly restricted air inlet and also higher auctions at cranking speeds, and the increased suction of itself results in better vaporization of the gasoline. If the passageway 49 should be left open and unrestricted during the choking action of even through the restricted orifice '59. In

the valve 29, then the restricting efiect of that valve can not be carried as far as if the fuel inlet 49 were restricted; otherwise, so

gine that it would be flooded at the first fire.

Under the above conditions, the low temperature bends the thermostat 50 away from the end of the jet 48, and the resistance of the bore 49 is at a minimum. After the engine has been started and warmed up, it is no longer desirable to have an increased fuel supply relative to the amount of air being used, and the choke valve 28 is opened.

As the temperature increases resulting in an increase in the amount of suction required at the venturi to draw in a given volume of air, the effect of the increased suction on the jet 48 is obviated by the movement of the thermostatic bafile member 50 toward the end of the jet under the influence of the increased temperature.

It will be understood that the member 50 can beadjusted so that it will cover any desired portion of the end of the bore 49 or so that the port 59 will be full or partly in registration with the end of the bore 49.- The portion of the cylinder wa ls to be exposedmember 51 is shown as a single piece of metal furnishing a rigid support for the thermo stat. It will be understood, however, that this member-could also be formed in the same way as the member 50 with the metal so arranged as to have an effect cumulative to that of the thermostat 50. Ordinarily, the space between the inside of thermostat 50 and the head of the. jet 48 at low temperatures is a proximately one-third of the diameter of t e bore 49. This space is shown somewhat exaggerated for clearness of illustration.

It will be understood that, under special conditions, such as startin no attempt is made 'to maintain an exac y constant fuel ratio, because the desirabilit of excess'fuel under these conditions is wellknown. Also, when the motor is heated to extreme temperatures, a ve lean mixture although quite eflicient, 1s undesired, because it tends to further heat the motor, becausethe combustion of a weak mixture occurs at a comparatively slow rate, causing the combustion chamber, piston -hea and the upper to the flame for longer periods. The heating effect is increased b the exposure of a greater part of the 'cy der walls to the flame on account of the fact that the slower burning mixture continues to burn as the piston recedes, and the flame comes in contact with the cylinder walls as they are uncovered by the piston; whereas, with ,a proper mixture the combustion would be near completion'before any substantial portion of the cylinder walls had been uncovered.

It will be seen that this device, when properly adjusted, is capable of maintaining a substantial, constant fuel-air ratio under normal operating conditions, and that the abnormal conditions at low temperatures are taken much raw fuel would be drawn into the encare of by the manually operated choke,

limit, an increase of the fuel to air ratio is permitted due to the fact that a part of the opening 49 is never closed, permitting the increased suction to draw greater quantities of the thin, hot fuel through the carburetor. As above explained, the increased suction is due to the fact that the increased volume of the air at these tem eratures makes it necessary to open the t rottle wider to permit a given volume of air to be drawn into the engine, thus increasing the suction on the jet on account of the higher velocity through the venturi.

It will be understood that, while no connection from the inlet 3 to an exhaust stove is shown, I contemplate using this carburetor on the usual type of automobile en e, and mounting it under the hood in this usual manner. As automobile engines also have an exhaust pipe exposed to the atmosphere under the hood, it will be seen that the air will be heated by the exhaust manifold u on operation of the engine, no matter whe er the air comes directly from the air stove or not.

It will be understood that the invention is susceptible of many modifications, and, accordingly, I do not Wish to be limited in my protection, except as set forth in the accompanying claims.

I claim:

1. In a carburetor, a fuel chamber, a main supply jet, a calibrated passa way providing communication between t e fuel chamber and said main jet, a perforated thermostatic late mounted adjaoent the entrance of sai passagewa said perforation forming a metering ori ce being of smaller diameter than said passageway, and means to move the perforated portion of said plate toward and away from said p w 2. In a carburetor, a fuel cham r, a fuel jet adapted to be supplied with fuel from said chamber, a discharge port leading from said fuel chamber toward said jet, a movable plate mounted in said fuel chamber adjacent said discharge port, a perforation in said late of smaller diameter than said port, and

eat controlled means for adjusting the position of said plate with respect to said port.

'3. In a carburetor, a mixing conduit for fuel and air, a source of fuel supply, a calibrated passagewa leading from said source of supply towa said conduit, a membe mounted adjacent one end of said p w way having a perforation therein of less diameter than said passageway, such devices being constructed and arranged to permit alternatively around the member and heat controlled means for moving said member toward or away from said passageway.

4. In a carburetor, means forming a mixing conduit, a fuel conduit for delivering fuel to said mixing conduit, said mixing conduit having an air inlet and said fuel conduit having a fuel inlet, valve means for controlling one of said inlets, a portion of said valve being cut away to establish a predetermined minimum passageway when the valve is in closed 'positlon, and means for controlling said Valve by heat and suction to vary the mixture of air and fuel from rich to lean as the temperature and suction increase.

5. In a carburetor, means forming a mix ing conduit, a fuel conduit for delivering fuel to said mixin conduit, said mixing conduit having an an inlet and said fuel conduit having a fuel inlet, valve means for controlling one of said inlets, a portion of said valve being cut away to establish a predetermined minimum passageway when the valve is in closed position, means for operating said valve by heat and suction to vary the mixture of air and fuel from lean to rich, and vice versa, a throttle valve in said mixing conduit for controlling the discharge of mixture therefrom, and a suction connection leading from a point in said mixing conduit posterior to said throttle and adapted to apply suction to said valve for operating it to lean out the mixture.

6. In a plain tube carburetor, means forming a mixing conduit, means for admitting air to said mixing conduit comprising an air inlet, means for admitting fuel to said mixing conduit comprising a fuel inlet, a valve 1n one of said inlets, means for causing said valve to respond to either suction or temperature changes and thereby lean out the mixture upon an increase of suction or temperature or both, and to enrich the mixture upon a decrease of suction or temperature or both, and a perforation in said valve to provide a predetermined minimum restriction to said inlet.

7. In a plain tube carburetor, means forming a mixing conduit, means for admitting air to said mixing conduit comprising an air inlet, means for admitting fuel to said mixin conduit comprising a fuel inlet, a valve in one of said inlets, means for causing said valve to respond to either suction or temperature changes and thereby lean out the mixture upon an increase of suction or temperature or both, and to enrich the mixture upon a decrease of suction or temperature or both, a suction connection leading from a point in said mixing conduit posterior to said throttle for operating said valve, and a perforation in said valve to provide a predetermined minimum restriction to said inlet.

In testimony whereof I aflix mg si ature.

GEORGE R. E I SON.

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