US2616405A - Enrichment device and method of controlling the same - Google Patents

Description

4 Sheets-Sheet l AREA Y INCHES MERCURY E. BARTHOLOMEW ENRICHMENT DEVICE AND METHOD OF CONTROLLING THE SAME' INTAKE MANIFOLD VACUJM AT FULL THROTTLE, INCHES MERCURY M /FULL THROTTLE /7 INTAKE MANIFOLD VACUUM,

CARBURETOR VENTURI VACUUM AT FULL THROTTLE, INCHES MERCURY INVENTOR.

EARL BARTHOLOMEW BY YMW FIGURE l ENGINE SPEED,.REVOLUT!ONS PER MINUTE CAR SPEED, MILES PER HOUR LEVEL ROAD LOAD Nov. 4, 1952 Filed Nov. 20, 1948 mmumizz uz .oO hzwimEqamm 200212.24 4m?- Nov. 4, 1952 E. BARTHOLOMEW 2,616,405

ENRICHMENT DEVICE AND METHOD OF CONTROLLING THE SAME Filed Nov. 20, 1948 4 Sheets-Sheet 2 INTAKE MANIFOLD VACUUM AT FULL THROTTLE, INCHES MERCURY CARBIRETOR VENTURI VACUUM AT FULL THROTTLE, INCHES MERCURY 0.9 L5 2.4 3.3 4.0 4 5 96 A AREA X FULL THROTTLE LEVEL ROAD LoAu- FUEL ANTIKNOOK REQUIREMENT, OOTANE NUMBERS AIR CONSUMPTION, POUNDS PER HOUR I200 I600 2000 2400 2800 3200 ENGINE SPEED, REVOLUTIONS PER MINUTE l I I I I I 30.6 40.8 5L0 6L2 7L4 8L6 GAR SPEED, MILES PER HOUR FIGURE 2 IN V EN TOR.

EARL BARTHOLOMEW Nov. 4, 1952 BARTHQLOMEW 2,616,405

ENRICHMENT DEVICE AND METHOD OF CONTROLLiNG THE SAME Filed NW. 20, 1948 I 4 Shefits-Sheet 3 Ffi D m g 4 Q E X pz w INVENTOR.

EARL BARTHOLOMEW BY h Nov. 4, 1952 E. BARTHOLQMEW 2,616,405

ENRICHMENT DEVICE AND METHOD OF CONTROLLING THE SAME Filed Nov. 20, 1948 4 Sheets-Sheet 4 FIGURE 4 DECREASE IN KNOCKING TENDENCY OF COMMERCIAL GASOLINES DUE TO MIXTURE ENRICHMENT t g I! Ill 2 l5 2 RANGE OF IMPROVEMENT To BE u ExPEcTED WITH vARlous TYPES E OF PRESENT COMMERCIAL '6 GASOLINES o l- Z J l 5 O no 0 2 U D Z I lw 2 Q 0 O 2 x E l m J (I) Ill 2 O I.|.| D

0 IO 4oso PERCENT ENRICHMENT mom MAXIMUM KNOCK AIR-FUEL RATIO 116* |2.5 ".5 ms 9.9 9.2 8.6 AIR-FUEL mmo INVENTOR. MAXIMUM KNOCK AIR'FUEL RATIO OF THE AVERAGE COMMERCIAL GASOLINE EARL BARTHOLOMEW Patented Nov. 4, 1 952 ENRICHMENT DEVICE AND METHOD OF CONTROLLING THE SAME Earl Bartholomew, Birmingham, Mich., assignor to Ethyl Corporation, New York, N. Y., a corporation of Delaware Application November 20, 1948, Serial No. 61,172

1- My invention relates to methods and ap aratus for regulating the enrichment of the fuel-air mixture over that normally fed to an internal combustion engine so that knocking i reduced over the range of engine operation while at the same time the consumption of fuel is minimized.

This is accomplished by controlling such enrichment of the mixture jointly in accordance with variation in the intake manifold vacuum of the engine, and its rate of air-consumption.

My invention can be best understood, by referring to the drawings in which;

Figure 1 is a plot of fuel antiknock requirement of a typical hi h compression engine with automatic transmission over the speed range from 1200 to 3200 revolutions per minute, corresponding to vehicle speeds of approximately 30.6 to 81.6 miles per hour on a level road, at full throttle and for various conditions of constant intakemanifold vacuum.

Figure 2 is a plot similar to Figure 1 except that curves of constant air-consumption have been superimposed and the curves of constant intake manifold have been omitted for the sake of clarity.

Figure 3 is a schematic drawing partially in cross-section, illustrating parts of a conventional carburetor plus a device for controlling an enriching supply of the gasoline from the fuel tank of the vehicle.

Figure 4 is a plot showing the range of decrease in knocking tendency in the octane rating of commercial gasoline resulting from the use of mixture ratios richer in fuel than that for maximum knock.

In the normal operation of passenger car, truck and bus engines, knocking occurs during only a small fraction of the tota1 operating time, and hence during the consumption of only a small fractionjof the total gasoline used. The fuel antiknock requirement of such engines usually increases as the manifold vacuum decreases until it reaches a maximum at full throttle conditions. In addition the octane requirement of the engine decreases as engine speed increases, for full throttle operation and for conditions of constant intake manifold vacuum, as can be best understood by referring to Figure 1, in which curve A, M, B, represents the octane number requirement at full throttle over a range of engine-s peedsfor a particular engine. Curves CDQEF, GH, IJ and KL represent the fuel octane number requirement, over the speed range at constant manifold vacuums of 5.5, 8.0, 9.5, 11.5 an'd13i5 'inchesof'mercury, respectively. The

4Claims. (01. 123-427) term vacuum as used hereinis defined as the differential in pressure between atmospheric and that at 'the point of measurement. The broken line OP shows the octane number requirement for level road operation over a range of constant engine and corresponding constant vehicle speeds. The data represented in Figure 1 were obtained on a car having an automatic transmission which operates in a lower gear at road speeds below about 30 miles per hour with resulting increase in engine speed. Therefore the chart does not extend below a road speed of 30.6 miles per hour or an engine speed of 1200 revolutions per minute. For cars having a conventional changegear transmission, the proportional scales of engine and car speed in high gear would be extended to the left, as would curves AMB, CD, EF, GH, LT and KL.

It is observed that this engine would require a 96 octane number fuel to give completely knockfree operation over the included speed range and yet this peak requirement occurs only at full throttle and at an engine speed of 1200 revolutions per minute. Thus there would be consider able excess of fuel antiknock quality when using thisfuel at other operating conditions. If the engine were supplied with an 87 octane number fuel, the engine would knock at all combinations of speed and manifold pressure above those represented by the 87 octane number line, which is the solid straight line connecting points E and M. Under all other conditions this engine would give knock-free operation on this fuel.

Present day. automobile engines generally operate with full throttle maximum power airfuel ratios of from 12.8 to 13.521. overall air-fuel ratios and the air-fuel ratio of the mixture being supplied to the individual cylinders may vary considerably from these values. The maximum knocking tendency of commercial gasoline generally occurs between 13.5 to 14.5:1 air-fuel ratio. Hence when knocking occurs, the

leanest cylinders usually are the ones responsible,

other factors being equal.

As the mixture is made progressively richer than the maximum knock air-fuel ratio, the knocking tendency of the mixture decreases quite rapidly. This effect of rich air-fuel ratios on decreasing the knocking tendencies of fuels has been widely used for controlling knocking in aircraft engines during maximum power output conditions.

Figure 4 shows the approximate range of the decrease in knocking tendency of present commercial motor gasolines resulting from the use These are one octane number increasein the ,QlltozlOdrange;

than in the 70 to 80 octane number range. Because of this difierence in sizeofroctanenumbers,

the lower the octane number ofthetank-fuelthe more octane number improvement can :be....texpected, other factors being equal, for a given amount of mixture enrichment. However, the few octane. numbers ,obtainableatLtha-higher. level arejust ,asvaluable as.v the largerimproyementi in octaneunits atthe lowerlevel.

In present. day. engines, .mixtureenrichmentof between to 401% usually-.maybemade atllow speeds without adverse efl'e.cts..from,.th.e standpointof engine performance. .At higher engine speeds substantial enrichment .do'es resultflina loss inenginepower. v.Mydevice, however, limits the enrichment ,toalbwlspee'd range ofioperation where it is required for control ofknocking and therefore.avoidslosspf'power ldueto enrichment at the higher speeds.

Thus mixtureenrichment' alone, canbe. used to meet at least a par-tiof the peak. fuel antiknock requirement of the .engine which occurs .at .or near open throttle and at the low engine speeds. Such enrichment enables the. useofLa tank gasolinehaving a lower. octane lnumberthanthepeak requirement of the engine. Howevenwith the usual commercial gasoline. enrichment for octane requirementlof .Lthe engine .isnotneeded at. the higher speeds .orpatengine conditions represented by area -Y .QfLJiigure' 1- or area Z of Figure 2. ,Any enrichment under. conditions iof opeiiationrepresented'byzllheseallleas iswa'stedl It,is,.therefore, an object of "this. invention to provide a method of mixture enrichment with varying engine conditions in which enrichment is reduced or stopped as the speed .ofitheiengine is increased, thus minimizing thetamount ofl'fuel used'and yet satisfying at least aportion of the antiknock requirements" of the engine; In other words my object is "to avoid mixtureenrichment under conditions'represented"by area Y'of Figure 1 and area Z of-Figure-2 'andtopmployenrichment only-under conditionsirepresented by area X of'these figures; A further object of" my invene tion is to meet at least partially-the antiknock requirement ofthe engine at lowqspeed whilesubstantially avoiding loss of power associated'wit enrichment "at-the higher speeds.

I accomplish these obj ects' in the following'manner: My device for controlling enrichmentin accordance-withlvarying engine conditions is actuated jointly by the manifold vacuumandby the vacuum in a venturi, which may belthe conventional carburetor venturi, located ahead of the throttle. The vacuum inthe Venturi is directly related to 'the'ra t'eo'f air-consumption. Asthe flow of air becomes greater with increase in'en gine speed or throttle opening, the vacuuminthe Venturi-increases, tending first to reduce and then to st'opthe flow of'enrichi-ngfuel.

Control of the enriching device by manifold vacuum alone will not accomplish the objects of my invention. For instance if the engine whose octane requirement data are shown in Figure 1 is supplied with an 87 octane number tank gasoline the fuel will just meet the requirement of the engine .at .8 inches of mercury; manifoldwacuum at :an engine speed of l2il0i.revolutions.per minute (point E). Enrichment then will occur at all manifold vacuum less than 8.0 inches of mercury. Thus if the enrichment is controlled by manifold vacuumalone such a device will supply the additional fuel over the entire speed range underallconditions.represented by the area above thezlineEF,.i;.-e.,area X (defined by points A,

M',-.-E) zandshadedarea Y (defined by points E, M, BHF, El, whereas knock suppressing, and hence enrichment;*are required only under conditions represented by area X.

Likewise the controlo'f enriching fuel solely by change of vacuum .in the venturiasthe rateroi aireconsumptionv changes does notaccomplish the objectsof myinvention. To illustrate, reference is made to Figure 2.Which.is;simila'r." to Figure: 1 except that curves'of lconstant vacuum are omit+ ted for, sake of 'clarity, andcurves of constant rates of air consumption are. superimposeiindicated by' the quantities 385,520; 636, 728, and 810 which express pounds per hour.

If theenrichingvalve werecontrolled by Venturi vacuum alone and it weredesired to, operate this engine on a tank'fuel havingB'l'octane numher, the enriching valve wouldv be adjusted to close ata Venturi vacuum of approximately 3.3 inches of mercury corresponding to an airflow of '728jpounds perhour i. e. the air consumption at full throttle. at 2400 revolutionsper. minute (point M). At higher speeds, the, fullthro-ttle octane number requirementjsj less, than .857. By this control alone, injection would. occur on.;a level roadunder all constant. speed engine conditions represented by area X(previously defined). and area Z (defined by.E;.M, N',P, .0). ,.i. e..all.the area above the. level. road li'ne...lO'P'.. Areas jbelow line OP represent conditions of'operationwherein the .vehicleis. either. decelerating or descending a grade. With .this .method' Ofcontrol, .flow of enriching .fueL would also occur. underthe .latter conditions, representedlby the:area.extending.below line OP. I

Thus itis seen that-neither control alone is sumcient .to provide at least.,a..portion.of.the. antiknockrequiitementsof- .theeng-inewithout waste of antiknock quality, fiuel'or both. However, when the enriching'valve is under the joint .controlnf the manifold vacuum and the Venturi vacuumtas shown in Figure "3 and subsequently described herein, the areas o'fithe .two diaphragms subjected to these twovacuums can 'beproportioned so as to provide complete cutofi'along the-broken line connecting points Eand M in Figures. 1 and 2. Enriching, then, occurs. only under engine conditions represented by 'thearea above this line where the additional antiknock. .quality is .required. Also by the joint, control',...mo.dulation.of flow is provided so.'that.the-amount .of.enrichment is approximately proportioned .to the variations in knocking which would occur with .the primary fuel alone as conditions of .engineoperation are'ch'anged.

The engine whose octane requirementrelationships are shown in 'Figuresl and 2' can bewsubstantially satisfied antiknockwisefby .the use of n 87 octane number tank' fuelgin conjunction with enrichment. Howevenwithtank fuels havto the engine.

ing octane number ratings substantially lower than 8'7, enrichment alone would not be an entirely satisfactory means of completely meeting the antiknock requirements at the lower speeds.

However enrichment alone will satisfy at least I my invention eliminates enrichment for engine conditions represented by area Y in Figure 1 and area Z in Figure 2. This result cannot be obtained through control of enrichment by either manifold vacuum or means related to air consumption alone.

Referring to Figure 3, a device is illustrated for controlling the enriching supply of fuel join ly by intake manifold vacuum and carburetor Venturi vacuum. While Figure 3 illustrates an embodiment of my invention in which the control device is incorporated with the carburetor, it is to be understood that my control device could be an entirely separate unit. Fuel line I is connected to a special carburetor 2 and a conventional pump and fuel supply (not shown). Fuel fed to the carburetor is referred to herein as the tank fuel. In general it is a commercial fuel composed in whole or in part of hydrocarbons and in most cases containing an antiknock agent such as tetraethyl lead. However it may contain other antiknock agents or other fuels such as alcohols.

The tank fuel flows into float chamber 3 and then through a conventional carburetor jet 4 wherein the flow is controlledby a conventional metering rod 5 whose movement is integrated with throttle opening. The fuel then flows through passageway 6 to fuel tube 1 which is located in the carburetor venturi 8. The equipment described so far is merely one type of design intended to give conventional air-fuel ratios used in motor car operation. These full throttle air-fuel ratios are generally in the neighborhood of from 12.8 to 13.5 to 1. In addition to the conventional carburetion controls, float chamher 3 contains an enriching control valve 9 which provides another avenue for fuel to flow into passageway 6 and into the carburetor venturi 8 thereby enriching the fuel-air mixture supplied The amount of enrichment beyond the standard air-fuel ratio depends on the quantity of fuel flowing through valve 9. Valve 9 is controlled by the regulating valve mechanism lb. The regulating valve mechanisms l8 comprises two vacuum-actuated elements such as diaphragms II and I2 which are operatively connected to stem 13 of enriching valve 9. Spring I4 holds valve 9 normally in an open position allowing additional fuel to flow into passageway 6 thereby providing a rich air-fuel mixture to the engine. Leakage from chambers 15 and I6 is prevented by bellows type seals I! attached to the valve stem [3. Chamber l5 connects through line l8 to the intake manifold is, and chamber it through line and passageway 2l to the carburetor venturi 8. Thus means are provided for actuating diaphragms l I and 12 by vacuums in the intake manifold and the venturi, and for applying this action to the valve stem. An increase in manifold vacuum. due either to a decreased throttle opening or an increase in enginespeed, or an increase in Venturi vacuum clue to increase in rate of air flow through the venturi will tend to close valve 9. At all times the total force acting on the valve stem is the sum of the forces produced by the two diaphragms. The enriching valve and the control diaphragms can be so designed that the rate of reduction of flow of enriching fuel will follow any desired pattern of speed and manifold vacuum for a given engine and thus permit operation on a tank fuel having any reasonable selected octane number. By proper proportioning of diaphragms H and i2 and adjustment of the tension on spring 14 by nut 22, the cut-off pattern illustrated in Figures 1 and 2 can be obtained.

The net effective areas of the two diaphragms required to close the valve under either of the combinations of intake manifold and carburetor Venturi vacuums, corresponding to points E and M of Figures 1 and 2, is easily calculated by solving two simultaneous equations. One equation can be set up for the closing force on the valve at point E. This closing force is equal to the sum of the intake manifold vacuum and carburetor Venturi vacuum at point E multiplied by the net effective area of each of their respective diaphragms H and I2. A similar equation can be set up for the closing force on the valve at point M. These two closing forces are equal hence the two equations can be solved for the relative areas of the two diaphragms. The actual areas of diaphragms II and I2, in the calculated ratio, should be just sufiicient for their combined forces to compress the chosen spring i4 and close valve 9 under conditions corresponding to points E and M. Usually it is desirable to have the diaphragms small for con venience. At the other speeds and throttle openings between points E and M, the combined effect of diaphragms I2 and I3 results in the closure of the injection valve substantially in accordance with the broken line EM of Figures 1 and 2.

Once the areas of the two diaphragms are proportioned for a given engine and for a tank fuel of a given octane number, approximate adjustments for use with a different octane number tank fuel within a reasonable range can be made by nut 22. The size of the opening in valve seat 23 is so selected. that when valve 9 is wide open, a sufficient amount of additional fuel will flow to prevent knocking at low speed and wide-open throttle. The relative amount of additional fuel required will depend on the octane number requirement of the engine and the octane numher and hydrocarbon composition of the tank fuel, and is usually from 10 to 40 per cent of that which flowssimultaneously through the regular carburetor metering system. For over-the-road operation the additional amount of fuel required due to enrichment generally is from 1 to 15% of the total fuel consumed.

During the start of acceleration from low speed with an automatic transmission, or in high gear with a conventional change-gear transmission, the engine is usually operated at full throttle by the average driver of the vehicle. If the driver continues acceleration at full throttle, as he frequently does, the vacuum in the carburetor venturi increases with the increase in engine speed, causing diaphragm [2 to move the enriching fuel valve toward the closed position. When a speed and Venturi pressure corresponding to point M of Figures 1 and 2 have been reached, the valve --closes completely. --At higher speeds-no enrich- -ment occurs.

-With a conventional change-gear transmission, acceleration in first or second gears is often done-at part throttle, as may also be done with an automatic transmission. 7 In this event'enrich- -ment is cut off under conditions represented by broken line EM. Thus the use of myainvention generally results in a largesav-ing of enrichment fuel during acceleration.

All-vehicles operate a part of the-time under engine-conditions represented byarea-X of Figures-1 and-2'and would therefore receive the benefitof modulated enrichment providedby my device. All"vehicles.alsooperatea part-of the time, and some, such as trucks and busses, the

-. greater,,-.-part of theatime .under conditions replresented byarea Yof Figure 1 and area Z of Fig- -ure 2, under which conditions --no enrichment occurs during the-use of my device. Thus under any condition-of engine operation the use of my invention limits theconsumption of additional fuel to :a minimum necessary and thereby effects large savings 'overa device controlled either by .manifold vacuum or carburetor Venturi'vacuum an internal combustion engine having-:an air-intake manifold and-an air intake-venturiseparated from each other by a throttle-"valve,"said method comprisingsupplementing the amount of fuel normallysupplied to the said-engine es isentially only while i the operating" conditions thereof are such .as tocause knocking, by controlling the supply of fuel in accordance with'the combined effect of ichanges i both the Venturi vacuum'and-the air intake manifold vacuum, increasing the supplemental: supply whenever the air consumption rate decreases and whenever the -manifoldvacuu'm decreases, and decreasing the supply whenever the air consumption rate increases and whenever the manifold vacuum increases. I I

2. -'-A device for"enr-iching the fuel-airmixture 's'uppl-ied' to a-n internal combustion engine that has an intake manifold and a carburetor with a venturi and a throttle valve connected to control the delivery of "fuel to -'-the engine" by controlling 'the flow through the venturi' and into' the intake manifold, said device comprisingsup'plemental fuel -supply structure, regulating means having 'two' control elements for separate connection to respond respectively to the intakefimanifold vacuum and to 'the Venturi-vacuum; each'of said elements being connected to the supplemental fuel supply structure to separately open the supplemental fuel" supply in response to decreases in its actuating vacuum, and to'separat'ely closethe ture ior' increasing the-supplemental supply in response to the additive effects of any decrease prising in combination a carburetor with a pri- '-mary valve for supplying" the normal amount of *"in manifold vacuum and any decrease inalr consumption rate, and for decreasing the supplemental supply in response to the additive effects of any increase in manifold'vacuum and any increase in air consumption to limit the supplementalifuel supply substantially to those operating conditions in which there would be a tendency for knocking to occur.

3. A device for enriching the fuel-air mixture supplied to an internal combustion engine comfuel to theengine, and a dual actuated auxiliary valve for supplying additional amounts of the same fuel to said engine, said auxiliary valve being controlled by two diaphragms, one of which is connected to. fully respond to any change in the vacuum in thescarburetor venturi and the other-of which is connected to fully respond to any change in the vacuum in the air-fuel intake manifold, each of said diaphragms being connectedto the auxiliary valve to separately open this valve in response to decreases-in the diaphragm-actuating vacuum and close this valve in response to increases in the diaphragm-actuating vacuum, said diaphragms being permanent-ly linked 'to'each other as well as to said auxiliary valve'to move the auxiliary valve toward the vacuum to which it responds, the responses of the individual diaphragms being adjusted for limiting the opening of the auxiliary valve to substantiallythose operating conditions in which there would be a tendency for knocking to occur. 4. "A method for improving the performance of an internal combustion engine having an air supply, a iuelsupply, and an air-intake manifold and supplied with a mixture of fuel and air for combustion, said method comprising varying the fuel-air ratio when said engine would knock at the normal fuel-air ratio, by adding supplemental fuel in accordance with the joint and additive effect of any change in the amount of air supplied to the engine and any change in the vacuum in the air intake manifold, increasing the fuelair ratio as said combined effect increases, and decreasing the fuel-airratio as said combined effect decreases.

EARL B-ARTI-IOLOMEW.

REFERENCES CITED .-The following references are ofrecordin the file of this patent:

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