US008069839B2
`
`(12) United States Patent
`Cohn et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,069,839 B2
`Dec. 6, 2011
`
`(54) FUEL MANAGEMENTSYSTEM FOR
`VARABLE ETHANOL OCTANE
`ENHANCEMENT OF GASOLINE ENGINES
`
`(75) Inventors: Daniel R. Cohn, Cambridge, MA (US);
`Leslie Bromberg, Sharon, MA (US);
`John B. Heywood, Newtonville, MA
`(US)
`(73) Assignee: Massachusetts Institute of Technology,
`Cambridge, MA (US)
`
`(*) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`(21) Appl. No.: 13/117,448
`(22) Filed:
`May 27, 2011
`
`(65)
`
`Prior Publication Data
`US 2011 FO22621.0 A1
`Sep. 22, 2011
`
`Related U.S. Application Data
`(63) Continuation of application No. 12/815,842, filed on
`Jun. 15, 2010, now Pat. No. 7,971,572, and a
`continuation of application No. 12/329.729, filed on
`Dec. 8, 2008, now Pat. No. 7,762,233, and a
`continuation of application No. 1 1/840,719, filed on
`Aug. 17, 2007, now Pat. No. 7,740,004, and a
`continuation of application No. 10/991,774, filed on
`Nov. 18, 2004, now Pat. No. 7,314,033.
`
`(51) Int. Cl.
`(2006.01)
`F02B 700
`(52) U.S. Cl. ..................... 123/431; 123/198A:123/575
`(58) Field of Classification Search .................. 123/295,
`123/299, 300,525, 27 GE, 198A, 575, 1A,
`123/559.1, 527
`See application file for complete search history.
`
`(56)
`
`References Cited
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`Primary Examiner — Hai Huynh
`(74) Attorney, Agent, or Firm — Sam Pasternack; MIT's
`Technology Licensing Office
`
`ABSTRACT
`(57)
`Fuel management system for efficient operation of a spark
`ignition gasoline engine. Injectors inject an anti-knock agent
`Such as ethanol directly into a cylinder of the engine. A fuel
`management microprocessor system controls injection of the
`anti-knock agent so as to control knock and minimize that
`amount of the anti-knockagent that is used in a drive cycle. It
`is preferred that the anti-knock agent is ethanol. The use of
`ethanol can be further minimized by injection in a non-uni
`form manner within a cylinder. The ethanol injection Sup
`presses knock so that higher compression ratio and/or engine
`downsizing from increased turbocharging or Supercharging
`can be used to increase the efficiency of the engine.
`20 Claims, 3 Drawing Sheets
`
`fuel managerrent
`microprocessor
`14
`
`
`
`knock
`SS
`12
`
`ethanol tank
`16
`
`
`
`
`
`gasolire tank
`18
`
`aris
`20
`
`
`
`turbocharger
`22
`
`FORD Ex. 1101, page 1
` IPR2020-00013
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`

`US 8,069,839 B2
`Page 2
`
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`* cited by examiner
`
`FORD Ex. 1101, page 2
` IPR2020-00013
`
`

`

`U.S. Patent
`
`Dec. 6, 2011
`
`Sheet 1 of 3
`
`US 8,069,839 B2
`
`ethanol tank
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`fuel management
`microprocessor
`14
`
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`
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`
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`
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`
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`
`.
`
`W
`
`knock
`
`SeSOf
`2
`
`engine
`O
`
`
`
`
`
`
`
`
`
`6 anoa . . . . . . . . . . . .
`
`
`
`
`
`
`
`
`
`
`
`asoline tank
`
`gas - manifold
`20
`
`--a a's 's', 's 's', 's', 's
`
`
`
`turbocharger
`22.
`
`FG,
`
`14.
`
`
`
`S. 120
`t s
`OC
`g
`80
`C.
`
`SP
`to
`
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`
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`
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`O.
`
`0.2
`O4.
`0.6
`0.8
`fraction of energy from ethanol
`FG, 2.
`
`O
`
`FORD Ex. 1101, page 3
` IPR2020-00013
`
`

`

`U.S. Patent
`
`Dec. 6, 2011
`
`Sheet 2 of 3
`
`US 8,069,839 B2
`
`Swir notic
`
`cooler charge
`with ethano
`for knock Control
`
`air marifold
`
`Swiri motion
`
`
`
`
`
`
`
`cooler charge
`with ethario
`for knock Control
`
`
`
`F.G. 3
`
`FG, 4.
`
`air raioid
`
`r
`ethanol manifold injection
`
`FORD Ex. 1101, page 4
` IPR2020-00013
`
`

`

`U.S. Patent
`
`Dec. 6, 2011
`
`Sheet 3 of 3
`
`US 8,069,839 B2
`
`ethanol tank
`16
`
`re
`
`fuel management
`microprocessor
`14
`
`Knock
`
`SeSOf
`
`12
`
`gasol tank
`mM
`
`manifold
`2O
`
`engine
`10
`
`
`
`
`
`
`
`
`
`
`
`
`
`turbocharger
`22
`
`F.G. S.
`
`FORD Ex. 1101, page 5
` IPR2020-00013
`
`

`

`1.
`FUEL MANAGEMENT SYSTEM FOR
`VARABLE ETHANOL OCTANE
`ENHANCEMENT OF GASOLINE ENGINES
`
`This application is a continuation of U.S. patent applica
`tion Ser. No. 12/815,842 filed Jun. 15, 2010 which is a con
`tinuation of U.S. patent application Ser. No. 12/329,729 filed
`on Dec. 8, 2008 which is a continuation of U.S. patent appli
`cation Ser. No. 1 1/840,719 filed on Aug. 17, 2007, which is a
`continuation of U.S. patent application Ser. No. 10/991,774,
`which is now issued as U.S. Pat. No. 7,314,033.
`
`BACKGROUND
`
`This invention relates to spark ignition gasoline engines
`utilizing an antiknock agent which is a liquid fuel with a
`higher octane number than gasoline Such as ethanol to
`improve engine efficiency.
`It is known that the efficiency of spark ignition (SI) gaso
`line engines can be increased by high compression ratio
`operation and particularly by engine downsizing. The engine
`downsizing is made possible by the use of Substantial pres
`Sure 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 techniques to increase engine effi
`ciency, however, is limited by the onset of engine knock.
`Knock is the undesired detonation of fuel and can severely
`damage an engine. If knock can be prevented, then high
`compression ratio operation and high pressure boosting can
`be used to increase engine efficiency by up to twenty-five
`percent.
`Octane number represents the resistance of a fuel to knock
`ing but the use of higher octane gasoline only modestly alle
`viates the tendency to knock. For example, the difference
`between regular and premium gasoline is typically six octane
`numbers. That is significantly less than is needed to realize
`fully the efficiency benefits of high compression ratio or
`turbocharged operation. There is thus a need for a practical
`means for achieving a much higher level of octane enhance
`ment so that engines can be operated much more efficiently.
`It is known to replace a portion of gasoline with Small
`amounts of ethanol added at the refinery. Ethanol has a blend
`ing octane number (ON) of 110 (versus 95 for premium
`gasoline) (see J. B. Heywood, “Internal Combustion Engine
`Fundamentals.” McGraw Hill, 1988, p. 477) and is also
`attractive because it 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 ethanol that is readily available is
`much smaller than that of gasoline because of the relatively
`limited amount of biomass that is available for its production.
`An object of the present invention is to minimize the amount
`of ethanol or other antiknock agent that is used to achieve a
`given level of engine efficiency increase. By restricting the
`use of ethanol to the relatively small fraction of time in an
`operating cycle when it is needed to prevent knock in a higher
`load regime and by minimizing its use at these times, the
`amount of ethanol that is required can be limited to a rela
`tively small fraction of the fuel used by the spark ignition
`gasoline engine.
`
`SUMMARY
`
`In one aspect, the invention is a fuel management system
`for efficient operation of a spark ignition gasoline engine
`
`10
`
`15
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`US 8,069,839 B2
`
`2
`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 of the air-fuel charge to the
`cylinder when it is injected directly into the engine. This
`cooling effect reduces the octane requirement of the engine
`by a considerable amount in addition to the improvement in
`knock resistance from the relatively high octane number of
`ethanol. Methanol, tertiary butyl alcohol, MTBE, ETBE, and
`TAME may also be used. Whereverethanol is used herein it is
`to be understood that other antiknock agents are contem
`plated.
`The fuel management system uses a fuel management con
`trol system that may use a microprocessor that operates in an
`open loop fashion on a predetermined correlation between
`octane number enhancement and fraction of fuel 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 and that its use be minimized during these
`times. Alternatively, the gasoline engine may include a knock
`sensor that provides a feedback signal to a fuel management
`microprocessor System to minimize the amount of the ethanol
`added to prevent knock in a closed loop fashion.
`In one embodiment the injectors stratify 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.
`In another embodiment of this aspect of the invention, the
`system includes a measure of the amount of the antiknock
`agent such as ethanol in the source containing the antiknock
`agent to control turbocharging, Supercharging or spark retard
`when the amount of ethanol is low.
`The direct injection of ethanol provides substantially a 13°
`C. drop in temperature for every ten percent of fuel energy
`provided by ethanol. An instantaneous octane enhancement
`of at least 4 octane numbers may be obtained for every 20
`percent of the engine's energy coming from the ethanol.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a block diagram of one embodiment of the inven
`tion disclosed herein.
`FIG. 2 is a graph of the drop in temperature within a
`cylinder as a function of the fraction of energy provided by
`ethanol.
`FIG. 3 is a schematic illustration of the stratification of
`cooler ethanol charge using direct injection and Swirl motion
`for achieving thermal stratification.
`FIG. 4 is a schematic illustration showing ethanol stratified
`in an inlet manifold.
`FIG. 5 is a block diagram of an embodiment of the inven
`tion 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
`
`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 fuel management micropro
`cessor System 14 controls the direct injection of an antiknock
`agent such as ethanol from an ethanol tank 16. The fuel
`management microprocessor system 14 also controls the
`delivery of gasoline from a gasoline tank 18 into engine
`
`FORD Ex. 1101, page 6
` IPR2020-00013
`
`

`

`US 8,069,839 B2
`
`15
`
`3
`manifold 20. A turbocharger 22 is provided to improve the
`torque and power density of the engine 10. The amount of
`ethanol injection is dictated either by a predetermined corre
`lation between octane number enhancement and fraction of
`fuel that is provided by ethanol in an open loop system or by
`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 14 will
`minimize the amount of ethanol added to a cylinder while still
`preventing knock. It is also contemplated that the fuel man
`10
`agement microprocessor System 14 could provide a combi
`nation of open and closed loop control.
`As show in FIG. 1 it is preferred that ethanol be directly
`injected into the engine 10. Direct injection substantially
`increases the benefits of ethanol addition and decreases the
`required amount of ethanol. Recent advances in fuel injector
`and electronic control technology allows fuel injection
`directly into a spark ignition engine rather than into the mani
`fold 20. Because ethanol has a high heat of vaporization there
`will be substantial cooling when it is directly injected into the
`engine 10. This cooling effect further increases knock resis
`tance 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
`cylinder is preferred because it is advantageous in obtaining
`good air/fuel mixing and combustion stability that are diffi
`cult to obtain with direct injection.
`Ethanol has a heat of vaporization of 840 kJ/kg, while the
`heat of vaporization of gasoline is about 350 kJ/kg. The
`attractiveness of ethanol increases when compared with gaso
`line on an energy basis, since the lower heating value of
`ethanol is 26.9 MJ/kg while for gasoline it is about 44 MJ/kg.
`Thus, the heat of vaporization per Joule of combustion energy
`is 0.031 for ethanol and 0.008 for gasoline. That is, for equal
`amounts of energy the required heat of vaporization of etha
`nol is about four times higher than that of gasoline. The ratio
`of the heat of vaporization per unit air required for stoichio
`metric combustion is about 94 kJ/kg of air for ethanol and 24
`kJ/kg of air for gasoline, or a factor of four Smaller. Thus, the
`net effect of cooling the air charge is about four times lower
`for gasoline than for ethanol (for Stoichiometric mixtures
`wherein the amount of air contains oxygen that is just suffi
`cient to combust ail of the fuel).
`In the case of ethanol direct injection according to one
`aspect of the invention, the charge is directly cooled. The
`amount of cooling due to direct injection of ethanol is shown
`in FIG. 2. It is assumed that the air/fuel mixture is stoichio
`metric without exhaust gas recirculation (EGR), and that
`gasoline makes up the rest of the fuel. It is further assumed
`that only the ethanol contributes to charge cooling. Gasoline
`is vaporized in the inlet manifold and does not contribute to
`cylinder charge cooling. The direct ethanol injection provides
`about 13° C. of cooling for each 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. However,
`under certain conditions there can be combustion stability
`issues.
`The temperature decrement because of the vaporization
`energy of the ethanol decreases with lean operation and with
`EGR, as the thermal capacity of the cylinder charge increases.
`If the engine operates at twice the stoichiometric air/fuel
`ratio, the numbers indicated in FIG. 2 decrease by about a
`factor of 2 (the contribution of the ethanol itself and the
`gasoline is relatively modest). Similarly, for a 20% EGR rate,
`the cooling effect of the ethanol decreases by about 25%.
`The octane enhancement effect can be estimated from the
`data in FIG. 2. Direct injection of gasoline results in approxi
`
`45
`
`4
`mately a five octane number decrease in the octane number
`required by the engine, as discussed by Stokes, et al. Thus the
`contribution is about five octane numbers per 30K drop in
`charge temperature. As ethanol can decrease the charge tem
`perature by about 120K, then the decrease in octane number
`required by the engine due to the drop in temperature, for
`100% ethanol, is twenty octane numbers. Thus, when 100%
`of the fuel is provided by ethanol, the octane number
`enhancement is approximately thirty-five octane numbers
`with a twenty octane number enhancement coming from
`direct injection cooling and a fifteen octane number enhance
`ment coming from the octane number of ethanol. From the
`above considerations, it can be projected that even if the
`octane enhancement from direct cooling is significantly
`lower, a total octane number enhancement of at least 4 octane
`numbers should be achievable for every 20% of the total fuel
`energy that is provided by ethanol.
`Alternatively the ethanol and gasoline can be mixed
`together and then port injected through a single injectorper,
`cylinder, thereby decreasing the number of injectors that
`would be used. However, the air charge cooling benefit from
`ethanol would be lost.
`Alternatively the ethanol and gasoline can be mixed
`together and then port fuel injected using a single injector per
`cylinder, thereby decreasing the number of injectors that
`would be used. However, the Substantial air charge cooling
`benefit from ethanol would be lost. The volume of fuel
`between the mixing point and the port fuel injector should be
`minimized in order to meet the demanding dynamic octane
`enhancement requirements of the engine.
`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 fuel management microprocessor system 14.
`An additional benefit of using ethanol for octane enhance
`ment is the ability to use it in a mixture with water. Such a
`mixture can eliminate the need for the costly and energy
`consuming water removal step in producing pure ethanol that
`must be employed when ethanol is 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.
`Since unlike gasoline, ethanol is not a good lubricant and
`the ethanol fuel injector can stick and not open, it is desirable
`to add a lubricant to the ethanol. The lubricant will also
`denature the ethanol and make it unattractive for human con
`Sumption.
`Further decreases in the required ethanol for a given
`amount of octane enhancement can be achieved with Stratifi
`cation (non-uniform deposition) of the ethanol addition.
`Directinjection can be used to place the ethanol near 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 of ethanol needed to obtain a given amount of
`octane enhancement. Because only the ethanol is directly
`injected and because it is stratified both 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 ethanol be added to those regions that
`make up the end-gas and are prone to auto-ignition. These
`regions are near the walls of the cylinder. Since the end-gas
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`US 8,069,839 B2
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`contains on the order of 25% of the fuel, substantial decre
`ments in the required amounts of ethanol can be achieved by
`stratifying the ethanol.
`In the case of the engine 10 having Substantial organized
`motion (such as Swirl), the cooling result in forces that ther
`mally 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 com
`pression 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
`15
`modest Swirls result in large separating (centrifugal) forces. A
`3 m/s Swirl motion in a 5 cm radius cylinder generates accel
`erations of about 200 m/s, or about 20 g’s.
`FIG. 3 illustrates ethanol direct injection and swirl motion
`for achieving thermal stratification. Ethanol is predominantly
`on an outside region which is the end-gas region. FIG. 4
`illustrates a possible stratification of the ethanol in an inlet
`manifold with Swirl motion and thermal centrifugation main
`taining stratification in the cylinder. In this case of port injec
`tion of ethanol, however, the advantage of Substantial charge
`cooling may be lost.
`With reference again to FIG. 2, the effect of ethanol addi
`tion all the way up to 100% ethanol injection is shown. At the
`point that the engine is 100% direct ethanol injected, there
`may be issues of engine stability when operating with only
`stratified ethanol injection that need to be addressed. In the
`case of stratified operation it may also be advantageous to
`stratify the injection of gasoline in order to provide a rela
`tively uniform equivalence ratio across the cylinder (and
`therefore lower concentrations of gasoline in the regions
`where the ethanol is injected). This situation can be achieved,
`as indicated in FIG.4, by placing fuel in the region of the inlet
`manifold that is void of ethanol.
`The ethanol used in the invention can either be contained in
`a separate tank from the gasoline or may be separated from a
`gasoline/ethanol mixture stored in one tank.
`The instantaneous ethanol injection requirement and total
`ethanol consumption overa drive cycle can be estimated from
`information about the drive cycle and the increase in torque
`(and thus increase in compression ratio, engine power den
`45
`sity, and capability for downsizing) that is desired. A plot of
`the amount of operating time spent at various values of torque
`and engine speed in FTP and US06 drive cycles can be used.
`It is necessary to enhance the octane number at each point in
`the drive cycle where the torque is greater than permitted for
`knock free operation with gasoline alone. The amount of
`octane enhancement that is required is determined by the
`torque level.
`A rough illustrative calculation shows that only a small
`amount of ethanol might be needed over the drive cycle.
`Assume that 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 1 percent of the time is spent above 0.9 maximum torque.
`Conservatively assuming that 100% ethanol addition is
`needed at maximum torque and that 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
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`drive cycle about 20 percent of the total fuel energy is con
`Sumed at greater than 50 percent of maximum torque since
`during the 10 percent of the time that the engine is operated in
`this regime, the amount of fuel consumed is about twice that
`which is consumed below 50 percent of maximum torque.
`The amount of ethanol energy consumed during the drive
`cycle is thus roughly around 6 percent (30 percentx0.2) of the
`total fuel energy.
`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 accord
`ing to the needs of the drive cycle.
`Because of the lower heat of combustion of ethanol, the
`required amount of ethanol 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 ethanol content would be about 9% of that of
`gasoline by weight, a number not too different from present
`day reformulated gasoline. Stratification of the ethanol addi
`tion could reduce this amount by more than a factor of two. An
`on-line ethanol distillation system might alternatively be
`employed but would entail elimination or reduction of the
`increase torque and power available from turbocharging.
`Because of the relatively small amount of ethanol and
`present lack of an ethanol fueling infrastructure, it is impor
`tant that the ethanol vehicle be operable if there is no ethanol
`on the vehicle. The engine system can be designed such that
`although the torque and power benefits would be lower when
`ethanol is not available, the vehicle could still be operable by
`reducing or eliminating turbocharging capability and/or by
`increasing spark retard so as to avoid knock. As shown in FIG.
`5, the fuel management microprocessor system 14 uses etha
`nol fuel level in the ethanol tank 16 as an input to control the
`turbocharger 22 (or Supercharger or spark retard, not shown).
`As an example, with on-demand ethanol octane enhance
`ment, a 4-cylinder engine can produce in the range of 280
`horsepower with appropriate turbocharging or Supercharging
`but could also be drivable with an engine power of 140 horse
`power without the use of ethanol according to the invention.
`The impact of a small amount of ethanol upon fuel effi
`ciency through use in a higher efficiency engine can greatly
`increase the energy value of the ethanol. For example, gaso
`line consumption could be reduced by 20% due to higher
`efficiency engine operation from use of a high compression
`ratio, strongly turbocharged operation and Substantial engine
`downsizing. The energy value of the ethanol, including its
`value in direct replacement of gasoline (5% of the energy of
`the gasoline), is thus roughly equal to 25% of the gasoline that
`would have been used in a less efficient engine without any
`ethanol. The 5% gasoline equivalent energy value of ethanol
`has thus been leveraged up to a 25% gasoline equivalent
`value. Thus, ethanol can cost roughly up to five times that of
`gasoline on an energy basis and still be economically attrac
`tive. The use of ethanol as disclosed herein can be a much
`greater value use than in other ethanol applications.
`Although the above discussion has featured ethanol as an
`exemplary anti-knock agent, the same approach can be
`applied to other high octane fuel and fuel additives with high
`vaporization energies such as methanol (with higher vapor
`ization energy per unit fuel), and other anti-knockagents such
`as tertiary butyl alcohol, or ethers such as methyl tertiary
`butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), or
`tertiary amyl methyl ether (TAME).
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`FORD Ex. 1101, page 8
` IPR2020-00013
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`7
`It is recognized that modifications and variations of the
`invention disclosed herein will be apparent to those of ordi
`nary skill in the art and it is intended that all such modifica
`tions and variations be included within the scope of the
`appended claims.
`What is claimed is:
`1. A spark ignition engine that is fueled both by direct
`injection and by port in