US1416857A - Carburetor - Google Patents

Description

. F. 0. Mock.

CARBURETOR.

APPLICATION FILED AUG-9,1919.

Patented May 23, 1922;.

3 SHEETS-SHEET .1.

F. C. MOCK.

CARBURETOR. APPLICATION FILED Aue .9, 1919.

. 1 1 57 Patented May 23, 19220 a SHEETSSH-EET a.

unites stares rarest FFHCZEO- FRANK c. MOCK, or cmoaeo, runners, assrenon no r s'rnoiaunne moron DEVICES COMPANY, CMCAGO, ILLINOIS, A CORPORATION OF ILLINQLS.

Specification of Letters Patent.

Patented May 23, 1222.

Original application filed August 25, 1915, Serial No. 47,385. Divided and this application filed August 9, 1919. Serial No. 316,309.

Z '0 all whom it may concern:

Be it known that I, FRANK C. MooK, a citizen of the United States, re'sidin at Chicago, in'th'e county ofCook and 'tate 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, forming a part of this specification.

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

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 and various loads, such as are attained and assumed in automobile practice, .a mixture with the most efficient proportions of air and fuel. it provide a device whereby thorough vaporization may be had, and wherein loading, that is the improper accumulation of fuel in the carbureting chamber and its subsequent improper supply to the engine, may be avoided, and in which, upon acceleration, the mixture may be temporarily surcharged with fuel.

This application is a division of my copending application Serial No. 47,385 filed August 25,1915, which resultedin Patent No. 1,420 1,879, dated January 31, 1922.

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 1 shall describe is an exemplary embodiment of my invention and toy which I 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 ofany invention;

Figure 2 is a vertical, axial sectionalview 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; Y

Figure 1- is a cross-sectional View of justing tion thereof, taken on the plane of the line :14 of Figure 2 and looking in the direction indicated by the arrows;

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

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 7-7 of Figure 6 and looking in the direction indicated by the arrows;

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

Referring first to Figure 2, it will be seen that 1 provide a carbureting chamber 9 suitably formed in the casing 10, which provides a passage from the air-inlet 11 to the ture Outlet 12. A main Venturi tube 13 is.

entry of liquid fuel, such as gasoline, into the float-chamber 19 by way of the pipe 22,

the float thus maintaining a constant level" at approximately the dot-and-dash line- .L 4 i V Between the float-chamber and the casing 10 I provide two wells, a primary well 23 and van accelerating well 24, the relative positions being best shown 1n Figure 6.

' The primary well 23 is connected with the i;

float-chamber 419 by way of passageways 25 and 26, the latter passageway being con-- trolled by a needle-valve 27. which, at its upper end, screws into and hangs from an adjusting nut 28 which determines the max imum open position of the valve. This adnut rests upon a sleeve 29, through which he needle-valve stem s de, and,

the s? hf nut Figure 8 also illustrates the pin 34, carried in the sleeve 29, which ehgages in a lon itudinal slot in the needle-valve stem 27,.so as to prevent the needle-valve from turnlng when the screw 28 is turned for adjust-5 .hne, while the lower end of the passagement. The passageway 26 isneverclosed but it will be seen that the ad ustment oi the nut 30 determines the lowermost position of the needle-valveand, thus, the mini? mumefi'ective size of the passageway which it governs. V From Figures2 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. n aperture 40 admits gasoline, assuming that to be the liquid fuel employed, from the primary 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 he described presently.

The tube 37 passes upwardly and connects exclusively with a passageway 42 near theupper end of the carburetor, which passageway communicates with a nozzle 43 in a plug 44 insertable in the casing 10 at a point in proximity to the closed position of the throttlh, as will be pointedout. An air-port 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 adjustable from the outside by means of the adjusting screw 47, a snap-spring 48 being provided to hold this adjusting 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 passageway in such a Way that it terminates slightly above the most restricted portion of the main Venturi tube, and the most restricted portion of this sec ondary Venturi tube therefore lying considerably further down. This secondary Venturi tube is mounted in a spider 53, which spans the air-passage. as clearly shown in Figures 2 and a, but leaves ample lar groove 54 is connected with the primary well 23 by means of the passa eway 56, it being noted that the fuel-nozz es 55, 55 he above the normal level of the gasoway 56 lies below it.

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

'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 thesurface 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 osition. When the. roller 60 drops into t e 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 60 rides upon the portion 58 of the cam, the needle-valve will be in its Ilppermost position.-

The shaft 15 of the intake-valve 14 is provided with the rising cam 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 dash adjustment, and under special conditions, the air may be restricted by the valve 14 and simultaneously the flow of gasoline into the primary well may be maximum by reason of the lifting of the needles 27 by the action of the cam regardless of the position of the throttle 16.

The accelerating well 24, which has hereinbefore been referred to, is fed directly from the float-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 well. is placed concentrically in the well, the interior of this tube being connected by means of ports 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 afuel-nozzle 73, terminating within the secondary Venturi tube slightly 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 series of ports 7%, 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-anddash line indicates the fuel level in the float-chamber, and. under ordinary conditions, the uppermost of these apertures lies above this fuellevel. Openings 75, 75 permit the entry of air into the space surrounding the tube 68.

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 depends upon the position in which the throttle is maintained when the engine iscranked, but it will sutiice as a. general statement to say that gasoline goes to the engine from the nozzle 43 and also from the fuel nozzles 55, 55, 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 enginecylinders. the lag in response of the gasoline. since the gasoline is heavier than air. and the excess of air.

In assuming now a conditionof 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 the nozzle 43 may feed over the throttle. Under these conditions air entering the main air-inlet passes upwardly through the Venturi tubes and into the passageway 45. where it goes into the 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 in a slight recess and the result is that there is a slight shunt path for air past the nozzle. This air. of course, goes to the engine with the mixture which comes from the nozzle 43. l nder these conditions the reduction in pressure below the throttle is so slight that no feed effect is had upon the jets in the secondary Venturi tube. The adjusting screw i6 is set for the proper admission of air in order to secure the best'mixture for idling and low running, it being evident that this mixture may be determined independently of consideration as to higher running. When the throttle is in this idling or low-running position the roller (50 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 needle valve 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 dashadjustment may be manipulated to slightly close of? the air in the main air-inlet 11.

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 branchof the slight shunt which has been referred to, and a slight en largement of the upper branch thereof, this resulting in a momentary increase in the suction on the nozzle 3, with a slight reduction in the amount of air passing thereby, thus slightly enriching the mixture, in accordance with the sligihtly-advanced-position of the throttle.

As the throttle is opened wider, the suction at 43 decreases and the issue therefrom decreases correspondingly, but at the same time the suction is increased below the throttle and the nozzles 55, 55 come into play. It will be remembered that up to thistime the nozzles 55 have been practically inert. for not only has there not been sufficient influence to raise the level of the gasoline in the passageway 56 toward the nozzles 55. 55. but the level has actuaily been lowered by the withdrawal of fuel through the aperture 40 and upwardly through the central passageway 38 and the tube 37. the throttle is opened. however, and suction becomes effective 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 Thus, as nozzle 43 gradually recedes in action with the opening movement of the throttle, the nozzles increase in action.

It will be seen that in the annular passageway 35) there is a certain amount of fuel above the aperture. 41 when the suction is not present to draw it out; but as soon as suction does become effective this fuel is drawn out and thereafter air. entering by wvay of the passageways 51, 5( and 49.

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 effect is secured within the secondary venturi 52, while the primary venturi 13 has a similar super-efiect upon the second Venturi tube as a nozzle. By this means the depression at the nozzles 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 on the 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 seems that the air charge delivered to the engine is rarefied and .of less density than wouldbe the case if the air velocity were less, thus preventing maximum air char e if the suction on the nozzle is to be sufhcient, and if the. single venturi is made of such size as to operate properly at low air velocities it will not be 'ade uate for the demand at high air velocities. y applicants arrangement only a small part of the air taken in by the 'motor'is raiscd to high velocity, and the maximum charge'of air is most efficiently secured on both low and high suctions simultaneously with I a maximum suction upon the nozzle. This result is secured basically by the use of two Venturi tubes,

with the secondary venturi outlet exposed at the point of greatest depression in the large venturi, a most important point since improper relation of the tubes makes the desired action impossible; then improved by the radial nozzles, since an axial nozzle in such a small tube creates eddy currents, and the carbureting action as a whole being further improved by air bleeding the nozzles. This last named point is important for this reason: It is an accepted fact that in an ordinary uncompensated carburetor the mixture tends to grow richer as the suction increases. The double venturi partly counteracts this tendency by reason of the easy passage of the air only between the two venturis and the bleeding of air into the jet also partly-counteracts this tendency, the other counteracting it entirely or practically so. If either of these devices were designed to do all the compensating, their purposes would be defeated. If the bleed were made large enough to do so, the liquid fuel would go out in slugs, and if the outer venturi were made too large it would not produce the desired effect upon the inner one. Thus, these two devices working together and in harmony, have been found to produce the desired result.

primary venturi are proper.

During this period of intermediate running less fuel than the suction would draw is entirely sufficient for theengine and the natural flow may be restricted for the sake' of economy since power at this time is not the main consideration. 0n 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 can not 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 needlevalve 27 may drop toits lowermost position and restrict the flow of gasoline from the float-chamber into the primary well 23. At the same time,the air which enters the fuel passageway by way of aperture 41, as has been described, displaces gasoline to a smallextent to keep down the supply.

As higher running takes place, however, the needle-valve 27 must again be raised to return to the position of maximum power, and this, as has been described is provided for by the riding of the roller 60 upon the surface 58 of the cam 57, maintaining the needle-valve 27 in its uppermost position throughout .the remainder of the range. It is important, however, in this connection, to point out that, as the higher suctions are attained, more, and more air is.

bled in through the aperture 41 and proportionately gasoline is displaced, so that,

although more gasoline is necessary on thehigher running, the provision of more in proportion is prevented and, as a matter of fact, overbalanced, so as to make the mixture somewhat leaner on the high speeds.

I come now to a consideration of the ac celerating well. What I desire isv a temporary surcharging of the mixture with gasoline upon acceleration, that is, at the beginning of a period of increased suction. This desirability follows from the natural inertia of the fuelfrom the main source, and the lag with which the-feed of fuel, being heavier than air, follows the position of the throttle; it is also due to the increased effort ot 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 eitecti've on the main source, the conditions are steady and further additional gasoline would be ex.- cessive'. It will be seen'that suction at the accelerating nozzle 73 is transmitted back through the passageways 72, 71 and 70 to the interior of the tube 68. This accelerating well does not feed on the'lower suctions for two reasons; first, because the nozzle 73 is at a higher plane than the main jets, and also because the uppermost apertures 74 in the tube 68 partly satisfy the suction," and it is not until this suction is not satisfied by the open apertures that gasoline responds.

lln assuming an act of acceleration, it will be clear that an increase in suction will be attended by an additional charge of gasoline from, the nozzle 4'3, 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 accelerating well except that which is drawn out to maintain the level where it has been brought. in other words, then gasoline flows out as fast as it iiows in. these two bleeders do not satisfy the suction, more gasoline will go to the carbureting chamber until the third bleeder is uncovered, and then again the test as to whether more gasoline is to go to the carbureting chamber is whether or not the three bleeders, 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 repeated 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 of the throttle. It will be understood, of course, that this adjustment is utilized, as is common in automobile pract ce,-to correct temporaryconditions. The 'oper amount of gasoline to h speed is by the proper sea -ng the having an air-inlet, and a mixture outlet, a

@n the other hand, it

screw 28. The proper amount of "asoline for intermediate running is determined by the proper setting of the adjusting nut 30. The adjustment for idling is determined by the adjusting screw 46. Unce determined it for a particular engine, these adjustments need no attention except for a marked change in climate or in the quality of the gasoline. As before stated for temporary conditions, such as starting in cold weather, the dash-adjustment is utilized to correct the action.

I claim 1- 1. In a carburetor, a carbureting chamber ill? throttle valve in said'outlet, a constant-level chamber supplying liquid fuel, a luehnozzle, a well connected with said constant-level chamber'and said nozzle, said nozzle being ted from said well slightly below the normal level therein, air being bled into said well slightly below the normal level, a second nozzle leading to said carbureting cham ber, above the throttle, from said well at a point below the lowest fuel-level therein, another well communicating with the atmosphere and fed from said constant-level chamber by a restricted passageway, and a fuel-tube leading from said well to said can bureting chamber.

2. In a carburetor, a carbureting chamber having an air-inlet and a mixture outlet, a throttle valve in said outlet, a constant level chamber supplying liquid fuel, a fuel-nozzle, a well connected with said constant-level chamber and said nozzle, said nozzle being led from said well slightly below the normal level therein, air being bled into said well slightly below the normal level, a second nozzle leading to said carbureting chamber, above the throttle, from said well at a point below the lowest fuel-level therein, another well communicating with the atmosphere and fed from said constant-level chamber by a restricted passageway, and a fueltube leading "from said well to said carbureting chamber at a point slightly above said first-named nozzle.

In a carburetor, a carbureting churnber having an air-inlet and a mixture outlet, a throttle valve in said outlet, aconstanh level chamber supplying liquid fuel, a fuelnozzle, a well connected with said constantlevel chamber and said nozzle, said nozzle being fed from said well slightly below 1- normal level therein, being bled into as well slightly below the normal l3, i, ond nozzle leading to said carburcoing c ber, above the throttle from said well point below the lowest tuelanother well communicating pl ers and ited from said cons her by a estric ice first-named nozzle, said fuel-tube being provided in said second well with a series of bleeder openings.

4. In a carburetor, a carbureting chamber having air and fuel inlets and a mixture outlet, a butterfly throttle in said mixture outlet, an opening in the wall of said carbureting chamber in proximity to the edge of the throttle when said throttle is in closed or substantially closed position, said opening being of such size that it extends beyond both sides of the throttle, a plug fitting in said opening but ending at a distance from the inner surface of said wall so as to form a recess, said plug having a'small passageway therethrough, and a fuel passageway leading to said small passageway.

5. In a carburetor, a carbureting chamber having a portion thereof in the form of a Venturi tube and having vfuel and, air. inlets and a mixture outlet, at throttle controlling said mixture outlet, a constant level fuel supply chamber, a fuel passageway leading from said fuel supply chamber to said carbureting chamber and discharging in proximity to the throttle when closed or substantially closed, and a passageway entirely above the fuel level in the supply chamber connecting said fuel passageway and said carbureting chamber between said throttle when closed or substantially closedand the most restricted zone of said Venturi tube.

In Witness whereof, I hereunto subscribe my name this 6th day of August, A. D. 1919.

FRANK G. MOCK. Witnesses:

BERTRAM WM. COLTMAN, JULIUs MILLER.

Images