`IN THE UNITED STATES PATENT AND TRADEMARKOFFICE
`
`Not Yet Assigned
`Examiner:
`Applicant: Daniel R. Cohnet al.
`
`Serial No.: Not Yet Assigned Art Unit:—Not Yet Assigned
`Filing Date: Filed Herewith
`Confirmation No.: Not Yet Assigned
`Title. FUEL MANAGEMENT SYSTEM FOR VARIABLE ETHANOL OCTANE
`ENHANCEMENTOF GASOLINE ENGINES
`
`PRELIMINARY AMENDMENT
`
`Via EFS-Web
`Commissioner for Patents
`P.O. Box 1450
`Alexandria, VA 22313-1450
`
`DearSir:
`
`Please preliminarily amend the application as follows.
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`FORD Ex. 1018, page 1
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`FORD Ex. 1018, page 1
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`Application No. Filed Herewith
`Date: June 15, 2010
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`Docket No.: 11381.109439
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`In The Specification
`
`Please amend paragraph [0001] on page 1 as follows:
`
`This application is a continuation of United States PatentApplication No. 12/329,729
`filed onDecember 8, 2008 whichis a continuation of United States Patent Application No.
`11/840,719 filed on August 17, 2007, whichis a continuation ofUnited States Patent Application
`No. 10/991,774, which is now issued as United States Patent No. 7,314,033.
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`Application No. Filed Herewith
`Date: June 15, 2010
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`Docket No.: 11381.109439
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`Listing of Claims
`
`Claims 1 — 32 (cancelled)
`
`(new) A spark ignition engine system for which fuel is introducedinto the engine from a
`33.
`first source and a fuel is separately introducedinto the engine from a sccond source by direct
`injection comprising:
`
`a spark ignition engine;
`a first means for introducing the fuel from thefirst source into the engine;
`a second meansfor direct injection ofthe fuel from the second sourceinto the engine,
`wherein during part ofthe engine operating time, the engine receives both the fuel from thefirst
`source and the fuel that is directly injected from the second source; and
`a fuel management system whichvaries the relative amount ofthe fuel from the second
`source that is introduced into the engine so as to prevent knock, wherein the fuel management
`system employs information from a knock detector and uses closed loop control to control the
`amountof directly injected fuel from the second source; and
`wherein the engine is opcrated with a substantially stoichiometric fuel/air ratio.
`
`34, (new) The engine system ofclaim 33, wherein the second source contains a liquid that
`could be employed to operate the engine without the addition of fucl from thefirst source.
`
`35. (new) The engine system ofclaim 33 or 34, wherein the fuel from the second sourceis
`alcohol.
`
`36.
`
`(new) The engine system of claim 35, wherein the alcohol is methanol.
`
`37.
`
`(new) The engine system of claim 35, whereinthe alcohol is cthanol.
`
`(new) The engine system of claim 33 where an alcohol-water mixture is directly injected
`38.
`into the engine from the second source
`
`(new) The engine system ofclaim 33 or 34, wherein the engine is turbocharged or
`39.
`supercharged
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`Docket No.: 11381.109439
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`40. (new) The engine system of claim 33 or 34, wherein the fuel from the first source is
`
`gasoline.
`
`41. (new) The engine system of claim 33 or 34, wherein the fuel from the second sourceis
`injected so as to result in a non-uniformdistribution in the engine cylinder.
`
`(ncw) The engine system of claim 41, whercin the fuel from the second sourceis injected so
`42.
`as to be more concentrated near the periphery ofthe engine cylinder, and
`the ratio of the energy of the fuel from the second source to fuel from the first source
`is sufficiently high to prevent knock but the alcohol energy fraction is reduced as
`compared to the situation using a uniform distribution.
`
`43. (new) The engine system ofclaim 33 or 34, wherein the fuel management system employs a
`microprocessorfor control of the relative amountoffuel from the second sourcethatis directly
`injected into the engine using information from a knock sensor, and
`wherein the relative amount ofthe fuel from the second source increases with increasing
`torque, and
`
`wherein the fuel management system minimizes the amount ofdirectlyinjected fuel from
`the second source that is used over a drive cycle.
`
`44. (new) The engine system ofclaim 43 further including open loop control with a look up
`table.
`
`45. (new) The engine system ofclaim 33, whercin spark retard is used and is varied according
`to the consumptionof the fuel from the second tank.
`
`(new) A spark ignition cngine system into whichfuelis introducedinto the engine froma
`46.
`first source and a fucl from a second sourceis introduced into the engine comprising:
`a spark ignition engine;
`a means for introducing fuel into the engine from thefirst source;
`a second means for introducing the fuel from the second sourceinto the engine wherein
`during part of the engine operating time, the engine receives both the fuel fromthefirst source
`and the fuel from the second source; and
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`Application No. Filed Herewith
`Date: June 15, 2010
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`Docket No.: 11381.109439
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`a fuel management system which varicsthe relative amountof the fuel from the second
`source that is introduced into the engine so as to prevent knock, wherein the fuel management
`system uses closed loop control to control the amount of fuel from the second source and
`
`employs information from a knock detector, and
`
`wherein the engine is operated with a substantially stoichiometric fuel/air ratio,
`
`(new) The engine system of claim 46, wherein the second source contains a liquid which
`47.
`could be used to operate the engine without fuel from the first source
`
`48.
`
`(new) The engine system of claim 46 or 47, wherein the fuel from the second sourceis
`
`alcohol.
`
`49. (new) The engine system of claim 48, whercin the alcohol is methanol.
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`50. (new) The engine system of claim 48, wherein the alcohol is ethanol.
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`51. (new) The engine system of claims 46 or 47, wherein the second source contains a fuel
`
`whichis an alcohol-water mixture.
`
`(new) The engine system of claims 46 or 47, wherein the engine is turbocharged to
`52.
`supercharged.
`
`53.
`
`(new) The engine system of claims 46 or 47, wherein the fuel from the first source is
`
`gasoline.
`
`54. (new) The engine system of claims 46 or 47, wherein the fuel management system employs
`a microprocessorfor control of the relative amountof fuel from the second source thatis
`introduced into the engine using information from a knock sensor, and wherein
`the relative amountof fuel from the second source increases with inercasing torque, and
`wherein the fuel management system minimizes the amountofdirectly injected fuel from
`the second source that is used over a drive cycle.
`
`(new) The engine system of claim 54 further including open loop control with a look up
`55.
`table.
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`Docket No.: 11381.109439
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`56. (new) The engine system of claims 46 or 47, wherein spark retard is used and is varied
`according to the consumption of the fuel from the second tank.
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`Application No. Filed Herewith
`Date: June 15, 2010
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`Docket No.: 11381.109439
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`Remarks
`
`Newclaims 33 — 56 moreparticularly point out and distinctly claim the invention. No
`new matter is being introduced.
`
`i!Respectful
`lySubmitted,
`if
`
`
`Sam Pasternack
`Registration No.: 29576
`Massachusetts Institute of Technology
`Five Cambridge Center
`Room NE25-230
`Cambridge, MA 02412-1493
`617.258.7171
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`Fuel ManagementSystem for Variable Ethanol Octane Enhancement
`
`of Gasoline Engines
`
`This application is a continuation of United Statcs Patent Application No. 11/840,719
`[0001]
`filed on August 17, 2007, whichis a continuation of United States Patent Application No.
`10/991,774, which is now issued as United States Patent No. 7,314,033.
`
`BACKGROUND
`
`This invention relates to spark ignition gasoline enginesutilizing an antiknock agent
`[0002]
`whichis a liquid fuel with a higher octane numberthan gasoline such as ethanol to improve
`engine efficiency.
`
`It is knownthatthe efficiency of spark ignition (SI) gasoline engines can be increased
`[0003]
`by high compression ratio operation andparticularly by engine downsizing. The engine
`downsizing is made possible by the use of substantial pressure boosting from either
`turbocharging or supercharging. Such pressure boosting makes it possible to obtain the same
`performance in a significantly smaller engine. See, J. Stokes, et al., “A Gasoline Engine
`Concept For Improved Fuel Economy ~ The Lean-Boost System,” SAE Paper 2001-01-2902.
`The use of these techniquesto increase engineefficiency, however,is limited by the onset of
`engine knock. Knock is the undesired detonation offuel and can severely damage an engine. If
`knock can be prevented, then high compression ratio operation and high pressure boosting can be
`uscd to increase engine efficiency by up to twenty-five percent.
`[0004] Octane numberrepresents the resistance of a fuel to knocking but the use of higher
`octane gasoline only modestly alleviates the tendency to knock. For example,the difference
`between regular and premium gasolineis typically six octanc numbers. Thatis significantly less
`than is neededto realize fully the efficiencybenefits of high compressionratio or turbocharged
`operation. Thereis thus a need for a practical means for achieving a much higherlevel of octane
`enhancementso that engines can be operated much more efficiently.
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`It is knownto replacea portion of gasoline with small amounts ofethanol added atthe
`[0005]
`refinery. Ethanol has a blending octane number (ON) of 110 (versus 95 for premium gasoline)
`(see J.B. Heywood, “Internal Combustion Engine Fundamentals,” McGraw Hill, 1988, p. 477)
`andis also attractive becauseit is a renewable energy, biomass-derived fuel, but the small
`amounts of ethanol that have heretofore been added to gasoline have had a relatively small
`impact on engine performance. Ethanol is much more expensive than gasoline and the amount
`of ethanolthatis readily available is much smaller than that of gasoline becauseoftherelatively
`limited amountof biomassthatis available for its production. An object of the present invention
`is to minimize the amountof ethanolor other antiknock agentthat is used to achieve a given
`level ofengine efficiency increase. Byrestricting the use of cthanolto the relatively small
`fraction of time in an operating cycle whenit is needed to prevent knockin a higher load regime
`and by minimizing its use at these times, the amount of ethanolthat is required can be limited to
`arelatively small fraction of the fucl used bythe spark ignition gasoline engine.
`
`SUMMARY
`
`In one aspect, the invention is a fuel managementsystem for efficient operation of a
`[0006]
`spark ignition gasoline engine including a source of an antiknock agent such as ethanol. An
`injector directly injects the ethanol into a cylinder of the engine and a fuel management system
`controls injection of the antiknock agent into the cylinder to control knock with minimum use of
`the antiknock agent. A preferred antiknock agent is ethanol. Ethanol has a high heat of
`vaporization so that there is substantial cooling ofthe air-fuel charge to the cylinder whenitis
`injected directly into the engine. This cooling effect reduces the octane requirementofthe
`engine by a considerable amountin addition to the improvementin knock resistance from the
`relatively high octane number ofethanol. Methanol, tertiary butyl alcohol, MTBE, ETBE, and
`TAMEmayalso be used. Wherever ethanolis used hereinit is to be understood that other
`
`antiknock agents are contemplated,
`[0007]
`The fucl managementsystem usesa fuel management control system that may use a
`microprocessor that operates in an open loop fashion on a predetermined correlation between
`octane number enhancementandfraction offucl provided by the antiknock agent. To conserve
`the ethanol, it is preferred that it be added only during portions of a drive cycle requiring knock
`resistance andthat its usc be minimized during these times. Alternatively, the gasoline engine
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`may include a knock sensorthat provides a feedback signal to a fucl management
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`microprocessor system to minimize the amountofthe ethanol added to prevent knock in a closed
`
`loop fashion.
`
`[0008]
`
`In one embodiment the injectors stratify the ethanol to provide non-uniform deposition
`
`within a cylinder. For example, the ethanol may be injected proximate to the cylinder walls and
`
`swirl can create a ring of ethanol near the walls.
`
`[9009]
`
`In another embodimentof this aspect of the invention, the system includes a measure
`
`of the amountof the antiknock agent such as cthanolin the source containing the antiknock agent
`
`to control turbocharging, supercharging or spark retard when the amountofethanol is low.
`
`{0010|
`
`The direct injection of ethanol provides substantially a 13°Cdrop in temperature for
`
`every ten percent of fuel energy provided by ethanol. Aninstantaneous octane enhancement of
`
`at least 4 octane numbers may be obtained for every 20 percentof the engine’s energy coming
`from the ethanol.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`{0011]
`
`FIG. Lis a block diagram of one embodimentof the invention disclosed herein.
`
`[0012]
`
`FIG. 2 is a graph of the drop in temperature within a cylinder as a function of the
`
`fraction of energy provided by ethanol.
`
`[0013]
`
`FIG, 3 is a schematic illustration ofthe stratification of cooler ethanol charge using
`
`direct injection and swirl motion for achieving thermalstratification.
`
`[0014]
`
`FIG. 4 is a schematic illustration showing ethanolstratified in an inlet manifold.
`
`[0015]
`
`FIG. 5 isa block diagram of an embodimentof the invention in which the fuel
`
`management microprocessor is used to control a turbocharger and spark retard based upon the
`amount of ethanol in a fuel tank.
`
`DETAILED DESCRIPTION
`
`[0016] With reference first to FIG. 1, a spark ignition gasoline engine 10 includes a knock
`
`sensor 12 and a fuel management microprocessor system 14. The fucl management
`
`microprocessorsystem14 controls the direct injection of an antiknock agent such as ethanol
`froman ethanol tank 16. The fuel management microprocessor system 14 algo controls the
`delivery of gasoline from a gasoline tank 18 into engine manifold 20. A turbocharger 22 is
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`provided to improve the torque and powerdensity of the engine 10. The amount of ethanol
`
`injection is dictated cithcer by a predetermined correlation between octane number enhancement
`
`and fraction offuel that is provided by cthanol in an open loop system orby a closed loop
`control system that uses a signal from the knock sensor 12 as an input to the fuel management
`microprocessor 14. In both situations, the fuel management processor L4 will minimize the
`
`It is also contemplated that
`amountof ethanol added to acylinder while still preventing knock.
`the fuel management microprocessor system 14 could provide a combination of open and closed
`loop control.
`
`[0017] As show in FIG.1 it is preferred that cthanol be directly injected into the engine 10.
`Direct injection substantially increases the bencfits of ethanol addition and decreases the required
`amount of ethanol. Recent advancesin fuel injector and electronic control technology allows
`fuel injection directly into a spark ignition engine rather than into the manifold 20. Because
`
`ethanolhasa high heat of vaporization there will be substantial cooling whenit is directly
`injected into the engine 10. This cooling effect further increases knock resistance by a
`considerable amount.
`In the embodiment of FIG. 1 port fuel injection of the gasoline in which
`the gasoline is injected into the manifold rather than directly injected into the cylinderis
`preferred becauseit is advantageousin obtaining goodair/fuel mixing and combustion stability
`that are difficult to obtain with direct injection.
`
`Ethanol has a heat of vaporization of 840kJ/kg, while the heat of vaporization of
`[0018]
`gasolinc is about 350kJ/kg. The attractiveness of ethanol increases when compared with
`gasoline on an energy basis, since the lower heating value of ethanol is 26.9MJ/kg while for
`gasolinc it is about 44MJ/kg. Thus, the heat of vaporization pcr Joulc of combustion cnergy is
`0.031 for ethanol and 0.008 for gasoline. Thatis, for equal amounts of energy the required heat
`of vaporization ofethanolis about four times higher than that of gasoline. Theratio of the heat
`of vaporization per unit air required for stoichiometric combustion is about 94 kJ/kg ofair for
`ethanol and 24 kJ/kg ofair for gasoline,or a factor of four smaller. Thus, the net effect of
`cooling the air charge is about four times lowerfor gasoline than for ethanol(for stoichiometric
`mixtures whercin the amount ofair contains oxygen thatis just sufficient to combust all of the
`fucl).
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`[0019]
`
`In the case of ethanoldirect injection according to one aspect of the invention, the
`
`chargeis directly cooled. The amount of cooling duc to direct injection of ethanol is shown in
`
`It is assumed that the air/fuel mixture is stoichiometric without exhaust gas recirculation
`FIG. 2.
`(EGR), and that gasoline makes up the rest of the fuel.
`It is further assumedthatonly the ethanol
`contributes to charge cooling. Gasoline is vaporizedin the inlet manifold and does not
`
`contribute to cylinder charge cooling. The direct ethanolinjection provides about 13°C of
`cooling for cach 10% of the fuel energy provided by ethanol.
`It is also possible to use direct
`injection of gasoline as well as direct injection of ethanol. [lowever, undercertain conditions
`
`there can be combustion stability issues.
`
`The temperature decrement because ofthe vaporization cnergy of the ethanol decreases
`[0020]
`with lean operation and with EGR,as the thermal capacity of the cylinder charge increases. If
`the cngine operatesat twice the stoichiometric air/fuel ratio, the numbers indicated in FIG. 2
`
`decrease byabouta factor of 2 (the contribution ofthe ethanolitself and the gasolineis relatively
`modest). Similarly, for a 20% EGRrate, the cooling effect of the ethanol decreases by about
`25%,
`
`[0021]
`
`The octane enhancementeffect can be estimated from the data in FIG. 2. Direct
`
`injection of gasolineresults in approximately a five octane numberdecreasein the octane
`
`number required by the engine, as discussed by Stokes, ef a/. Thus the contribution is about five
`
`octane numbers per 30K drop in charge temperature. As ethanol can decrease the charge
`temperature by about 120K, then the decrease in octane numberrequired by the engine due to the
`drop in temperature, for 100% ethanol, is twenty octane numbers. Thus, when 100% ofthe fuel
`is provided by cthanol, the octane number cnhanccmentis approximatcly thirty-five octane
`numbers with a twenty octane number enhancement coming from direct injection cooling and a
`fifteen octane number enhancement coming from the octane numberof ethanol. From the above
`considerations, it can be projected that even if the octane enhancementfrom direct coolingis
`significantly lower, a total octane number enhancementofat least 4 octane numbers should be
`
`achievable for every 20% ofthe total fuel energy that is provided by ethanol.
`[0022] Alternatively the ethanol and gasoline can be mixed together and then port injected
`through a single injector per cylinder, thereby decreasing the numberofinjectors that would be
`used. However, the air charge cooling benefit from ethanot would belost.
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`[0023]=Alternatively the ethanol and gasoline can be mixed together and then port fuel injected
`
`using a single injector per cylinder, thereby decreasing the numberofinjectors that would be
`
`used. However, the substantial air charge cooling benefit trom ethanol would be lost. The
`
`volumeof fuel between the mixing point and the port fuel injector should be minimizedin order
`
`to meet the demanding dynamic octane-enhancement requirements of the engine.
`
`[0024]
`
`Relatively precise determinations of the actual amount of octane enhancement from
`
`given amounts of direct ethanol injection can be obtained from laboratory and vehicle tests in
`
`addition to detailed calculations. These correlations can be used by the fucl management
`
`microprocessor system 14.
`
`[9025] An additional benefit of using ethanol for octane enhancementis the ability to use it in
`
`a mixture with water. Such a mixture can climinate the necd for the costly and energy
`
`consuming water removal slep in producing pure ethanol that must be employed when ethanolis
`
`added to gasoline at a refinery. Moreover, the water provides an additional cooling (due to
`
`vaporization) that further increases engine knock resistance. In contrast the present use of
`
`ethanol as an additive to gasoline at the refinery requires that the water be removed from the
`
`ethanol.
`
`{8026]
`
`Since unlike gasoline, ethanol is not a good lubricant and the cthanol fuel injector can
`
`stick and not open, it 1s desirable to add a lubricant to the ethanol. The lubricant will also
`
`denature the ethanol and makeit unattractive for human consumption.
`
`[0027]
`
`Further decreases in the required ethanol for a given amount of octane enhancement
`
`can be achieved with stratification (non-uniform deposition) of the ethanol addition. Direct
`
`injection can be used to place the cthanolnear the walls of the cylinder where the need for knock
`
`reduction is greatest. The direct injection may be used in combination with swirl. This
`
`stratification of the ethanol in the engine further reduces the amount ofethanol neededto obtain
`
`a given amount of octane enhancement. Because onlythe ethanolis directly injected and
`
`becauseit is stratified bath by the injection process and by thermal! centrifugation, the ignition
`
`stability issues associated with gasoline direct injection (GDI can be avoided.
`
`It is preferred that ethanolbe addedto those regions that make up the end-gas and are
`[0028]
`pronc to auto-ignition. These regions are near the walls of the cylinder. Since the end-gas
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`contains on the order of 25% ofthe fuel, substantial decrements in the required amounts of
`ethanol can be achieved bystratifying the ethanol.
`
`In the case of the engine 10 having substantial organized motion (such as swirl), the
`[0029]
`cooling will result in forces that thermally stratify the discharge (centrifugal separation of the
`regions at different density due to different temperatures). The effect of ethanol addition is to
`
`increase gas density since the temperature is decreased. With swirl the ethanol mixture will
`
`automatically move to the zone where the end-gas is, and thus increase the anti-knock
`effectiveness of the injected ethanol. The swirl motion is not affected much by the compression
`stroke and thus survives better than tumble-like motion that drives turbulence towards top-dead-
`center (TDC) and then dissipates.
`It should be pointed out that relatively modest swirls result in
`large separating (centrifugal) forces. A 3m/s swirl motion in a Scm radius cylinder gencrates
`accelerations of about 200m/s’, or about 20¢’s.
`
`FIG.3 illustrates cthanol direct injection and swirl motion for achieving thermal
`[0030]
`stratification. Ethanol is predominantly on an outside region whichis the end-gas region.
`FIG, 4 illustrates a possible stratification of the cthanol in an inlet manifold with swirl motion
`
`and thermal centrifugation maintaining stratification in the cylinder. In this case of port injection
`of ethanol, however, the advantage of substantial charge cooling maybelost.
`[9031] With reference again to FIG. 2, the effect of ethanol addition all the way up to 100%
`ethanolinjection is shown. At the point that the engine is 100% direct ethanol injected, there
`may beissues of engine stability when operating with only stratified ethanol injection that need
`to be addressed. In the case ofstratified operation it may also be advantageousto stratify the
`injection of gasoline in order to provide a relatively uniform cquivalenceratio across the cylinder
`(and therefore lower concentrationsof gasoline in the regions where the ethanolis injected).
`This situation can be achieved, as indicated in FIG. 4, by placing fuel in the region oftheinlet
`manifold that is void of ethanol.
`
`The ethanol usedin the invention can either be contained in a separate tank from the
`[0032]
`gasoline or may be separated from a gasoline/ethanol mixture stored in one tank.
`[0033]
`The instantaneousethanol injection requirement andtotal ethanol consumption over a
`drive cycle can be estimated from information aboutthe drive cycle and the increase in torque
`(and thus increase in compression ratio, engine power density, and capability for downsizing)
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`that is desired. A plot of the amount of operating time spent at various values of torque and
`
`engine speed in FTP and US06drive cycles can be used.
`
`It is necessary to enhance the octane
`
`numberat cach point in the drive cycle where the torque is greater than permitted for knock free
`
`operation with gasoline alone. The amount of octane enhancementthat is required is determined
`
`by the torque level.
`
`(0034] A roughillustrative calculation shows that only a small amount of ethanol might be
`
`needed over the drive cycle. Assumethat it is desired to increase the maximum torque level by a
`
`factor of two relative to what is possible without direct injection ethanol octane enhancement.
`
`Information about the operating time for the combined FTP and US06 cycles shows that
`
`approximately only 10 percent of the time is spent at torque levels above 0.5 maximum torque
`
`and less than | percent of the time is spent above 0.9 maximum torque. Conservatively
`
`assuming that 100 %ethanol addition is needed at maximum torque andthat the energy fraction
`
`of ethanol addition that is required to prevent knock decreases linearly to zero at 50 percent of
`
`maximum torque, the energy fraction provided by ethanol is about 30 percent. During a drive
`
`cycle about 20 percentofthe total fucl energy is consumedat greater than 50 percent of
`
`maximum torque since during the 10 percent ofthe time that the enginc is operated in this
`
`regime, the amount of fuel consumed is about twice that which is consumed below 50 percent of
`
`maximum torque. The amountof ethanol energy consumed during the drive cycle is thus roughly
`
`around 6 percent (30 percent x 0.2) of the total fuel energy.
`
`[0035]
`
`In this case then, although 100%ethanol addition was needed at the highest value of
`
`torque, only 6% addition was needed averaged over the drive cycle. The ethanol is much more
`
`effectively used by varying the level of addition according to the needs of the drive cycle.
`
`[0036]
`
`Because of the lower heat of combustion of ethanol, the required amount of cthanol
`
`would be about 9% of the weight of the gasoline fuel or about 9% of the volume(since the
`
`densities of ethanol and gasoline are comparable). A separate tank with a capacity of about 1.8
`
`gallons would then be required in automobiles with twenty gallon gasoline tanks. The stored
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`ethanol content would be about 9%of that of gasoline by weight, a numbernot too different
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`from present-day reformulated gasoline. Stratification of the ethanol addition could reducethis
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`amount by more than a factor of two. An on-line cthanol distillation system might altcrnatively
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`be employed but would cntail climination or reduction of the increase torque and poweravailable
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`from turbocharging.
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`[9037]
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`Because of the relatively small amount of ethanol and present lack of an ethanol
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`fueling infrastructure, it is important that the ethanol vehicle be operable if there is no ethanol on
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`the vehicle. The engine system can be designed such that although the torque and pewer benefits
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`would be lower when ethanolis not available, the vehicle could still he operable by reducing or
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`eliminating turbocharging capability and/or by increasing spark retard so as to avoid knock. As
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`shown in FIG.5, the fuel management microprocessor system 14 uscs cthanol fucl level in the
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`ethanol tank 16 as an input to control the turbocharger 22 (or supercharger or spark retard, not
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`shown). As an example, with on-demand ethanol octane enhancement, a 4-cylinder engine can
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`produce in the range of 280 horsepower with appropriate turbocharging or supercharging but
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`could also be drivable with an engine power of 140 horsepower without the use of ethanol
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`according to the invention.
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`[0038]
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`The impact of a small amount of ethanol upon fuel efficiency through use in a higher
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`efficiency engine can greatly increase the energy valuc of the ethanol. For example, gasoline
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`consumption could be reduced by 20% due to higher efficiency engine operation from use of a
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`high compressionratio, strongly turbocharged operation and substantial engine downsizing. The
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`energy value of the ethanol, including its value in direct replacement of gasoline (5% of the
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`energy of the gasoline), is thus roughly equal to 25% of the gasoline that would have been used
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`in a less efficient engine without any ethanol. The 5% gasoline equivalent energyvalue of
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`ethanol has thus been leveraged up to a 25% gasoline equivalent value. Thus, ethanol can cost
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`roughly up to five times that of gasolinc on an cnergy basis and still be cconomically attractive.
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`The use of ethanol as disclosed herein can be a much greater valuc usc than in other ethanol
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`applications.
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`[0039] Although the above discussion has featured ethanol as an exemplary anti-knock agent,
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`the same approach can be applied to other high octane fuel and fuel additives with high
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`vaporization energies such as methanol (with higher vaporization energy per unit fuel), and other
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`anti-knock agents suchas tertiary butyl alcohol, or ethers such as methy]tertiary butyl ether
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`(MTBE), cthyl tertiary butyl cthcr (ETBE), or tertiary amy! mcthyl cther (TAME).
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`It is recognized that modifications and variations of the invention disclosed herein will
`[0040]
`be apparent to those of ordinary skill in the art andit is intended that all such modifications and
`variations be included within the scope of the appended claims.
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`Whatis claimed is:
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`CLAIMS
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`1. Aspark ignition engine system for which fucl is introduced into the engine fromafirst
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`source and a liquid is separately introduced into the engine from a second source by direct
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`injection comprising:
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`a spark ignition engine;
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`a first means for introducing the fuel from thefirst source into the engine;
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`a second meansfordirect injection of the liquid from the second source into the engine,
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`wherein during part of the engine operating time, the engine reccives both the fuel from the first
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`source and the liquid that is directly injected from the second source; and.
`a fuel management system which variesthe relative amountofthe liquid from the second
`source that is introduced into the engine so as to prevent knock, wherein the fuel management
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`system employs information from a knock detector and uses closed loop control to control the
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`amountof directly injected liquid from the second source; and
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`wherein the engine is operated with a substantially stoichiometric fuel/air ratio.
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`2.
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`3.
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`4.
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`5.
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`6.
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`The engine system of claim 1, wherein the engine is turbocharged or supercharged.
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`The engine system of claim | or 2, wherein the liquid from the second sourceis alcohol.
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`The engine system of claim 3, wherein the alcohol is methanol.
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`The