US1404879A - Carburetor - Google Patents

Description

F. C. MOCK.

CARBURETOR. APPLICATION FILED AUGJS, 1915.

Patented Jan-31, 1922.

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31, 1922. 3 SHEETS-SHEET 2.

Patented Jan.

fn/ven/ior frank 0. [14 a];

F. C. MOCK.

CARBURETOR.

APPLICATION FILED AUG.25. 19-15.

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CARBURETOR.

APPLICATION FILED Aue.25.1u15.

Patented Jan. 31, 1922.

- 3 SHEETS-SHEET s. v

Irwe ra or fi al/n11 (Z Mock FRANK c.- MOCK, or carcass, rumors, assienon ro s'raonnnne moronrnvron COMPANY, or carcass, rumors, a conronr 'rronor rumors.

To all whom it may concern:

Be it known that l, FRANK C. M0011, a

citizen of the United States, residing at v Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Carburetors, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, tormin a part of this specification,

y invention relates to carburetors for internal-combustion engines and is concerned particularly with that class of carburetors now commonly known as plaintube devices; g

It is the object of my invention to provide a carburetor for the purpose referred to which will supply to the engine at the various speeds andvarious loads, such as are attained and assumed in automobile practice, a mixture with the most efficient proportions of air and fuel. ll provide a device whereby thorough vaporization may be had andwherein loading, that is the improper accumulation of fuel in the car: bureting chamber and its subsequent improper supply to the engine, may be avoided.

These and other advantages will become apparent to those skilled in the art as this description proceeds, it being understood that the device which 1 illustrate in the drawings and which I shall describe is an embodiment of my invention and to which ll am not necessarily limited, the scope of my invention being determined by the appended claims.

In the accompanying drawings,

Figure 1 is a side elevational view of the carburetor of my invention;

Figure 2 is a vertical, axial sectional view thereof;

Figure 3 is a cross-sectional view taken on the plane of the line 3-3 of Figure 2 and looking in the direction indicated by the arrows;

Figure 4 is a cross-sectional' View of a portion thereof. taken on the plane of the line 44 of Figure 2 and looking in the direction indicated by the arrows:

Figure 5 is a plan view of the structure of my invention, parts being broken away and shown in section to clearly reveal the structure thereof;

B'URETQRB Specification of Letters Patent. Paftgntgd Jan, 31; 192% Application filed august 25, 1915.

Serial No. 47,385.

Figure 6 is a vertical, cross-sectional view taken on the plane of the line 66 of Figure 5 and looking in the direction indicated by the arrows;

Figure 7 is a cross-sectional view taken on the plane of the line 77 of Figure 6 and looking in the direction indicated by the arrows;

Figure 8 is a detail view which will be referred to.

Referring first to Figure 2, it will be seen that l provide a carbureting chamber 9 suitably formed in the casing 10, which provides a passage from the air-inlet 11 to the mixture-outlet 12. A main Venturi tube 13 is set in this passageway, a butterfly valve 145 being mounted in the air intake upon a rotary shaft 15, and a throttle-valve 16 being mounted in the mixture-outlet upon a rotary shaft 17. A flange 18 surrounds the -mixture-outlet and is adapted for attachment to the manifold of positions being best shown in Figure 6.-

The primary well 23 is connected with the float-chamber 19 by way of passageways 25 and 26, the latter passageway being controlled by a needle-valve 27, which, at its upperend, screws into and hangs from an adj usting nut 28 which determines the maximum open position of the valve. This adjusting nut rests upon a sleeve 29, through which the needle-valve stem may slide, and the sleeve 29 rests upon an adjusting nut '30, through which the needle-valve stem may slide, this nut 30 threadinginto an extension 31 of float-chamber 19. It will be seen that the position of the needle-valve 27 determines the flow from the floatchamber into the primary well 28. The

nut 30 is held in any adjusted position by .means of a snap-spring 32, and the nut 28 is held in any adbe the liquid fuel employed, from the pri-' justed position by means of a snapspring 33 extending from the sleeve 29, the

, stem 27, so as to prevent the needle-valve from turning when the screw 28 is turned for adjustment. The passageway 26 is never closed, butit will be seen that the adjustment of the'nut 30 determines the lowermost position of the needle-val-ve,.and, thus, the minimum effective size of the passageway which is governs.

From Figures 2 and 6 it will be seen that a nipple 36 is disposed within the primary well 23, and a tube 37 is disposed within this nipple so as to form a central passageway 38 and an annular passageway 39. An aperture 40 admits gasoline, assuming that to mary well 23 to the central passageway 38, and an aperture 41 admits gasoline from the primary well 23 into the annular passageway 39, both of these apertures lying below the normal level of the fuel, and the latter aperture being mainly adapted for the reverse passage of air for a purpose to be described presently.

The tube 37 passes upwardly and connects exclusively with a passageway 42 near the upper end of the carburetor, which passage way communicates with a nozzle 43 44 insertable in the casing 10 at a point in proximity to the closed position of the throttle, as will be pointed out. An airport 45 connects the carbureting chamber 9, which lies below the throttle, with the passageway 42, and this connection is controlled by means of a needle-valve 46 ad'ustable from the outside by means of the a justing screw 47, asnap spring 48 being provided to in a plug hold this adjustmg screw in position.

The annular passageway 39 connects with:

the atmosphere by means of the passageway 49, the annular groove 50 around the Venturi tube 13, and the air-port 51.

A secondary Venturi tube 52 is mounted in the main passa eway in such a way that it terminates slig tl above the most re.-

- stricted portion of t e main Venturi tube,

the most restricted Venturi tube therefore lying considerably farther down. 'This seconda Venturi tube is mounted in agflspider 53, w ich spans the air-passage, as :elearly'shown in Figures 2 and 7, but leaves ample passage or air aroundit. Slightl above its most restricted portion this secon ary Venturi tube is provided with an annular groove 54, from which fuel inlets or'nozzles 55, 55 extend inwardly and radially, these nozzles being, preferably, distributed equidistantly upon the inner peri' hery. It will be seen t at 'air'is admis- Ele to the nozzles by way of the air port portion .of this secondary 51, groove 50, assageway 39 and aperture 41; a nozzle 0 this nature, wherein air is admitted to it, is known as an air-bled nozzle. The annular oove 54 is connected with the primary well 23 by means of the passageway 56, it being noted that the fuelnozzles 55, 55 lie above the normal level of the gasoline, while the lower end of the passaeway 56 lies below it.

pon the outside. of the carburetor, as shown in Figures 1 and 5, the shaft 17, upon which the throttle-valvev 16 is mounted, is provided with a cam 57, which has the circular periphery 58 concentric with the axis of the shaft, this cam-surface being complete except for the depression 59, which comes into play at a certain time, as will be described later.

Mounted upon a pivot-pin 59? upon the outside of the casing is a bell-crank lever having three arms, 60, 61 and 62. The arm 60 extends upwardly and at its upper end is provided'with a roller 60 adapted to ride upon the surface 58. The arm 61 extends horizontally and has its end bifurcated at 63, 63, to embrace the sleeve 29, hereinbefore referred to, below the shoulder 64 thereon.

It will now be seen that when the roller 60 rides upon the surface 58, which condition exists-on the higher speeds, the arm 61 of the bell-crank lever will engage the under side of the shoulder 64 on the sleeve 29 to lift the needle-valve 27 and keep it in its uppermost position. 'When the roller 60 drops intothe depression 59, as it will due to the location of the center of gravity of the bell-crank lever and the spring of the needle valve, it will be clear that the needlevalve 27 will be allowed to descend to its lowermost position. Again, when the roller vided with the risingcam 65, which is followed by a roller 66 on the arm 62 of the bell-crank lever. As illustrated in Figure 5, the shaft 15 is provided with an operating lever 66 at its opposite end, this operating lever being adapted to be connected with adjusting means, usually mounted on the dash of an automobile. This is a temporary 'dashadjustment, and under special conditions, the

air may be restricted by the valve 14 and simultaneously the flow of gasoline into the primary well 23 may be maximum by reason of the lifting of the needle 27 by the action "of thecam 65, regardless of the position of the throttle 16.

The acceleratin well 24, which has hereinbefore been re erred to, is .fed directly from thefloat-chamber 19 by means of the restricted passageway 67, shown in Figures 2 and 4. A tube- 68, which depends from a screw-plug 69, threaded in the top of this fuel-level.

well, is placed concentrically in the well, the interior of this tube being connected by means of ports 70 with an annular groove 71 in the plug 69. This annular groove 71, as illustrated in Figure 7, connects, by means of a small tube 72, with a fuel-nozzle 73, terminating within the secondary Venturi tube 52 shghtly above the fuel-nozzles 55, 55, as illustrated in Figure 2 and also in Figure 7. This fuel-nozzle I refer to as the accelerating nozzle and I shall describe its operation presently.

The tube 68 is provided with a seriiis of ports 74, arranged in vertical succession along the length of the tube, and, preferably, equidistantly spaced apart,as shown in Figure 6. In this figure the dot-and-dash line indicates the fuel level in the float-chamber, and, under ordinary conditions, the upper-most of these apertures lies above this Openings 75, 75 permit the entry of air into the space surrounding the tube 68. c g

The operation of the device is as follows: When there is no suction the gasoline stands at a common level in the float-chamber, the two wells, and the associated passageways. In starting, the response of the fuel de pends upon the position in which the throttle is maintained when the engine is cranked, but it will suffice as a general statement to say that gasoline goes to'the engine from the nozzle' l3 and also from the'fuel-jets 55, 55.

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Since, at starting, collected fuel stands in the passageways leading to these nozzles, there will be a desirable excess of fuel to compensate for the coolness of the engine-cylinders, the lag in response of the gasoline, since the gasoline is heavier than air, and the excess of air.

In assuming now a condition of idling or very low running, the throttle is closed as far as it can be, in which position, as shown in dotted line in Figure 52, the nozzle 43 may feed over the throttle. Under these condi:

tions air entering the main air-inlet passes upwardly through the Ventun tubes and into the passageway l5, where it goes intothe passageway 42, mixing with the rising gasoline and going on to the engine. it will.

be seen that the outlet of the nozzle 43 is'i n a slight recess and the result is that there is a slight shunt path for air past the nozzle. lhis air, of course, goes to the engine with the mixture which comes from the nozzle 43.

mixture may be determined independently of consideration as to higher running. When-:

the throttle'is in this idling or low-running position the roller on the bell-crank lever on the outside of the carburetor rests upon the portion '58 of the cam-surface and consequently, as before described, the needlevalve 27 is in its uppermost position, giving a full supply of gasoline. If, as for instance in colder weather, a somewhat richer mixture is desired under the circumstances, the dash-adjustment may be manipulated to plightly close oil the air in the main air inst 11.v

If it be now assumed that the throttle is gradually opened, it will be seen that the first effect, which will be of very short duration, however, will be a temporary restriction of the lower branch of the slight shunt which has been referred to, and a slight enlargement of the upper branch thereof, this resulting in a momentary increase in the suc-' ence to raise the level of the gasolinein the passageway 56 toward the nozzles 55, 55, but the level has actually been lowered by the withdrawal of fuel through the aperture 40 and upwardly throu h the central passage way 38 and tube 3 As the throttle is opened, however, and suction becomes efiective in the Venturi tube 52, a reverse action takes place and the gasoline rises in the passageway 56 to the point of issue from the nozzles 55, 55. 'Thus, as nozzle 43 gradually recedes in action with the opening movement of the throttle, the nozzles 55, 55 increase in action.

it will be seen that in the annularpassageway 39 there is a certain amount of fuel above the aperture 41, when the suction isnotpresent to draw it out; but as soon as suction does become effective this fuel is drawn out and thereafter air, entering by way of passageways 51, 50 and 49-, bleeds into the gasoline supply to the jets 55, 55. This actionis called compensation, being for the purpose of compensating for the tendency of the mixture to grow richer as the suction increases.

During this description of the operation of the nozzles 55, 55, it is opportune to refer to the double Venturi construction whereby the usual Venturi eii'ect is secured within the secondary venturi 52,- while the primary Venturi tube 13 has a similar super-efiect upon the secondary Venturi tube as a nozzle.

. is multiplied in large proportions, it being noted that the secondary venturi terminates at the, point of maximum depression in the primary venturi.

In the design of any carburetor there are two essential requirements, which to a certain extent oppose one another ;to deliver a maximum charge of air to the engine, and to exert the maximum atomizing effect upon the fuel, which atomizing effect is more or less a function of the suction or force by which the fuel is drawn from the nozzle. A strong suction onlthe nozzle usually involves a high air velocity past it, and to obtain a high air velocity in an ordinary single Venturi carburetor generally involves a considerable vacuum or depression in the intake manifold of the engine. This means that the air charge delivered to the engine is rarefied and of'less density than would be-the case if the air velocity were less, thus preventing maximum air char e if the suction on the nozzle is to be sufficient, and if the single venturi .is made of such size as to operate properly at low air velocities it will not be adequate for the demand at high air velocities. By applicants arrangement only a small part of the air taken in by the motor is raised'to high velocity, and the maximum charge of air is most efiiciently secured on both low and high suctions simultaneously with a maximum suction upon the nozzle.

This result is secured basically by the use of two Venturi' tubes, with the secondary venturi outlet disposed at the point of greatest. depression in the large venturi, a

most important point since improper relation of the tribes makes the desired action impossible; then im roved by the radial nozzles, since an axia nozzle in such a small tube creates eddy currents, and the carbureting action as a whole being then further Improved byair bleeding the nozzles.

This last-named point is important for this reason: It is arr-accepted fact that in an ordinary uncompensated carburetor the grow richer as the suction mixture tends to lncreases. ;The -double venturipartly eounteractsi this tendency by reason of the easy passage of air only between the two venturis and the bleeding of air into the jet also partlyrcounteracts thistendency, together counteracting it entirel or practically so. If eitherof these evices were designed todo all the com ensating, their purposes would be defeated. If the bleed were madelarge enough to do so the liquid fuel. would go out in slugs, and if the outer venturi were made too large it would not producethe desired effect upon the inner one. Thus, these two devices, working together and in harmony, have been found to produce the desired result.

As an example of correct relative sizes-it may be said that with an internal diameter of three-eights of an inch for the most restricted part of the secondary venturi, an external diameter of nine-sixteenths of an inch for the upper cylindrical portion thereof and an internal diameter of fifteensixteenths of an inch for the most restricted part of the primary venturi are proper.

During this period of intermediate running less fuel than the suction would draw is entirely sufficient 'for the engine and the natural fiowmay be restricted for the sake of economy since power at this time is not the main consideration. On the other hand it would be detrimental to permanently ,restrict the flow since then power would not be available In other words, power and economy cannot be secured with the'same' mixture and I therefore change the mixture to correspond to changed conditions. It is during this temporary period that the depression 59 in the cam 57 comes into play, so

that, as before described, the needle-valve 27 may drop to its lowermost position and'restrict the flow of gasoline from the floatchamber into the primary well 23. At the same time, the air which 'enterst-hefuel passageway by way of the aperture 41, as has been described, displaces gasoline to a small extent to keep down the supply.

As higher running takes place, however,

gasoline is necessary on the higher running,

the provision of more in proportion is prevented and, asa matter of fact, overbalanced, so "as to make the mixture somewhat leaner on the high speeds.

I come now to a consideration of the accelerating well. What I desire is a temporary surcharging of the mixture with gasoline upon acceleration, that is, atthe beginning of a period of increased suction, This desirability follows from the natural inertia of the fuel from the main source, and the lag with which the feed of fuel, being heavier than air, follows the position of the throttle; itis also due to the increased effort of the engine at that particular time. It is obvious that this extra feed of gasoline should be merely temporary, since, once the increased suction has become efi'ective on the main will be seenlthat suction at the accelerating attended by an additional chargeof gasoline from the nozzle 73, the size of this additional charge depending upon the amount of the increase; This regulation of the charge is due to the successive openings 74. For instance, when the suction reaches a point where it is not satisfied by the first bleeders 74, there will be a response of gasoline to the extent of the fuel above the second bleeders. This uncovers the second bleeders, and, if the two bleeders together satisfy the suction which has thus been attained, no further gasoline will issue from the acceleratin well except that which is .drawn out to maintain the level where is has been brought. In other words then gasoline flows out as fast as it flows in. On the other hand, if these tWo bleeders do not satisfy the suction, more gasoline will go to the carb'ureting chamber until the third bleeder is uncovered, and then again the test as to whether more gasoline is to go to the carburetin chamber is whether or not the three blee ers, or three sets of bleeders, satisfy the suction.

It will also be clear that, if the increased range of suction is maintained, the level in the accelerating well will be maintained at the point which was assumed when acceleration took place. Further acceleration to a still higher range is merely a matter of further similar action, as has been explained. If the suction is decreased, obviously the gasoline will rise by gravity head from the float-chamber 'to balance the decreased suction, and a re eated acceleration means merely a repetition of the operation which has been set forth.

Under any circumstances, the temporary dash adjustment is available to cut down the air and give maximum gasoline for any condition o the throttle. It will be understood, of course, that this adjustment is utilized, as is common in automobile practice, to correct temporary conditions.

' amount of gasoline for high speed is determined by the proper setting of the screw 28.

The proper amount of gasoline for intermediate running is determined by the lproper setting of the adjusting nut 30. T e ad- The proper justing screw 46. Once determined for a particular engine, these adjustments need no attention except for at marked change in climate or in the quality of the gasoline.

As before stated, for temporary conditions, such as starting in cold weather, the dashadjustment is utilized to correct the action.

Otherfeatures of novelty in the structure disclosed herein are claimed in my two copending divisional applications, Serial Nos. 316,308 and 316,309, filed August 9th, 1919.

I claim:

1. In a carburetor, a carbureting chamber having a mixture outlet, a Venturi tube'leading to said carbureting chamber, a second 'Venturi tube leading into'and terminating slightly beyond the most restricted zone of said first named Venturi tube, said Venturi tubes having their .axes substantially co-incident and having air inlets thereto, and a' fuel inlet leading into said second Venturi tube.

2. In a carburetor, a carbureting chamber having a mixture outlet, a Venturi tube leading into said carbureting chamber, a second Venturi tube leading into and terminating slightly beyond the most restricted zone of said first named Venturi tube, said Venturi tubes having their axes substantially co-incident and having air inlets thereto, and a fuel inlet slightly beyond its most restricted zone leading into said second Venturi tube.

3. In a carbureton-a carbureting chamber having a mixture outlet, a Venturi tube lead- .ing to said carbureting chamber, a second Venturi tube leading into said first named Venturi tube, said Venturi tubes having their axes substantially co-incident and having air inlets thereto, and a fuel inlet-leading laterally to and terminatingflush with justment for idling is determined by the ad- I the inner surface of said second Venturi tube.

4. In a carburetor, a carbureting chamber having a mixture outlet, a Ventnri tube leading tosaid carbureting chamber, a second Venturi tube leading into said first named Venturi tube, said Venturi tubes having their axes substantially co-incident and having air inlets thereto, a fuel inlet leading into said second Venturi tube, and means for admitting air to said fuel inlet anterior to its point of discharge into second Venturi tube.

In witness whereof I hereunto subscribe my name this 19th day of August A. D. 1915.

FRANK O. MOCK.

I Witnesses.

Lnsmn W. FRIcKn, Earner W. RAPALIE.

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