(12) United States Patent
`Pellizzari et al.
`
`(10) Patent No.:
`
`(45) Date of Patent:
`
`US 7,059,307 B2
`Jun. 13, 2006
`
`US007059307B2
`
`(54)
`
`(75)
`
`FUEL INJECTOR FOR AN INTERNAL
`COl\IBUSTION ENGINE
`
`Inventors: Roberto O. Pellizzari, Groton, MA
`(US); John Baron, Lexington, MA
`(US); Jan-Roger Linna, Boston, MA
`(US); Peter Loftus, Cambridge, MA
`(US); Peter Palmer, Waltham, MA
`(US); John Paul Mello, Belmont, MA
`(US); Stuart Bennett Sprague,
`Somerville, MA (US)
`
`(73)
`
`Assignee: Philip Morris USA Inc., Richmond,
`vA (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.: 10/870,634
`
`(22)
`
`Filed:
`
`Jun. 17, 2004
`
`(55)
`
`(53)
`
`(60)
`
`(51)
`
`(52)
`(53)
`
`(56)
`
`Prior Publication Data
`
`US 2004/0226546 A1
`
`Nov. 18, 2004
`
`Related U.S. Application Data
`
`Continuation of application No. 10/143,250, filed on
`May 10, 2002, now Pat. No. 6,779,513.
`
`Provisional application No. 60/367,121, filed on Mar.
`22, 2002.
`
`I11t. Cl.
`
`(2006.01)
`F02M 51/00
`U.S. Cl.
`..................................... .. 123/549; 123/557
`Field of Classification Search ...... .. 123/543—557,
`123/198 A; 219/206—207; 239/5, 13, 86—136;
`431/11—13, 121, 208—209
`See application file for complete search history.
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3,716,416 A
`
`2/1973 Aldhait et al.
`
`
`
`
`
`
`
`......... .. 123/179.15
`3/1975 Fricsc ct al.
`3,868,939 A *
`
`1/1976 Zillman et al.
`.... .. 123/557
`3,933,135 A *
`........... .. 123/557
`3,999,525 A * 12/1976 Stumpp et al.
`4,013,396 A
`3/1977 Tenney
`4,344,404 A
`8/1982 Child et al.
`
`(Continued)
`OTHER PUBLICATIONS
`
`Boyle et al., “Cold Start Perfomiance of an Automobile
`Engine Using Prevaporized Gasoine” SAE Technical Paper
`Series Society ofAutomotive Engineers, vol. 102, No. 3, pp.
`949-9.
`
`(Continued)
`
`Primary Examiner—Marguerite McMahon
`(74) Azzumey, Age/12, or Firm—Roberts, Mlotkowski &
`Hobbes
`
`(57)
`
`ABSTRACT
`
`A fuel injector for vaporizing a liquid fuel for use in an
`internal combustion engine. The fuel injector includes at
`least one capillary llow passage,
`the at least one capillary
`flow passage having an inlet end and an outlet end, a fluid
`control valve for placing the inlet end of the at least one
`capillary flow passage in fluid communication with the
`liquid fuel source and introducing the liquid fuel
`in a
`substantially liquid state, a heat source arranged along the at
`least one capillary flow passage, the heat source operable to
`heat the liquid fuel in the at least one capillary flow passage
`to a level sufficient to change at least a portion thereof from
`the liquid state to a vapor state a11d deliver a stream of
`substantially vaporized fuel from the outlet end of the at
`least one capillary flow passage and means for cleaning
`deposits formed duri11g operation of the apparatus. The fuel
`injector is eifective in reducing cold-start and Warm-up
`emissions of an internal combustion engine. Efficient com-
`bustion is promoted by forming an aerosol of fine droplet
`size when the substantially vaporized fuel condenses in air.
`
`23 Claims, 21 Drawing Sheets
`
`
`
`
`
`
`
`-\-\-\T\’=‘I"“
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`NU MARK Ex.1009 p.1
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`

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`US 7,059,307 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`6,192,596 B1
`
`2/2001 Bennett et a1,
`
`4472 133 A
`’
`’
`4,986,248 A
`5,127,822 A
`5,472,645 A
`5,482,023 A
`_
`5,692,095 A
`5,694,906 A
`5.743.251 A
`5,813,388 A
`5,870,525 A
`5,894,832 A *
`5,095,435 A
`6,102,687 A
`6,155,263 A
`6,162,046 A
`6,169,852 B1
`6,189,803 B1
`
`1
`9/1984 P
`elem“ 3.‘ 3'
`1/1991 Kobayashi ct al.
`7/1992 Nakayama et al.
`12/1995 Rocket al.
`1/1996 Hunt et al.
`ll/1997 Young
`12/1997 Lange et al.
`4/1998 Howell et al.
`9/1998 Cikzmek et al.
`2/ 1999 Y011I1g
`............... .. 123/491
`4/1999 Nogi et al.
`3/2000 scegers ct 31,
`8/2000 Butcher et al.
`12/2000 Takcuchi
`12/2000 Y011I1g 61 31~
`1/2001 Liao et al.
`2/2001 Ganan-Calvo
`
`6,195,504 B1
`6,200,536 B1
`6234 167 B1
`6’276’347 B1
`’
`’
`,,
`6,293,333 B1
`6,315,217 B1
`6,390,076 B1
`*
`,,
`6,779,513 B1
`6 871792 131*
`’
`’
`
`2/2001 Horie et al,
`3/2001 Tonkovich et al.
`5/2001 COK et 31
`'
`8/2001 Huim
`9/2001 Ponnappan et 211.
`11/2001 Park
`5/2002 Hunt
`-
`-
`8/2004 Pellizzari et al.
`......... .. 123/549
`
`3/2005 Pellizzari
`
`... N
`OTHER PUBLICATIONS
`
`.
`English abstract of JP 2000 110666.
`English abstract of DE 19546851.
`English abstract of EP 0,915,248.
`English translation of EP 0,915,248.
`
`* cited by examiner
`
`NU MARK Ex.1009 p.2
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`U.S. Patent
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`Jun. 13 2006
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`Jun. 13, 2006
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`US 7,059,307 B2
`
`1
`FUEL INJECTOR FOR AN INTERNAL
`COMBUSTION ENGINE
`
`RELATED APLICATIONS
`
`This patent application is a continuation of application
`Ser. No. 10/143,250, filed on May 10, 2002, now U.S. Pat.
`No. 6,779,513 claims priority to Provisional Application
`Scr. No. 60/367,121, filcd on Mar. 22, 2002, and is related
`to the following pate11t applications that are hereby incor-
`porated by referer1ce: “Method and Apparatus for Ger1erat-
`ing Power by Combustion of Vaporized Fuel;” by R. O.
`Pellizzari,
`filed on May 10, 2002; and “Apparatus and
`Method for Preparing and Delivering Fuel,” by R. O.
`Pellizzari, filed on May 10, 2002.
`
`FIELD
`
`The present invention relates to fuel delivery in an inter-
`nal combustion engine. More particularly, a method and
`apparatus according to the invention provides at least one
`heated capillary flow passage for vaporizing fuel supplied to
`an internal combustion engine.
`
`20
`
`BACKGROUND
`
`A variety of systems l1ave been devised to supply fine
`liquid fuel droplets and air to internal combustion engines.
`These systems either supply fuel directly into the combus-
`tion chamber (direct injection) or utilize a carburetor or fuel
`inj ector(s) to supply the mixture through an intake manifold
`into a combustion chambcr (indircct injection). In currently
`employed systems,
`the fuel-air mixture is produced by
`ato111izing a liquid fuel and supplying it as fine droplets into
`an air stream.
`
`30
`
`In conventional spark-ignited engines employing port-
`fuel injection, the injected fuel is vaporized by directing the
`liquid fuel droplets at hot components in the intake port or
`manifold, under normal operating conditions. The liquid fuel
`films on the surfaces of the hot components and is subse-
`quently vaporized. The mixture of vaporized fuel and intake
`air is then drawn into the cylinder by the pressure differential
`created as the intake valve opens and the piston moves
`towards bottom dead center. To ensure a degree of control
`that is compatible with modern engines,
`this vaporizing
`technique is typically optimized to occur i11 less than one
`engine cycle.
`Under most engine operating conditions, the temperature
`of the intake components is sufficient to rapidly vaporize the
`impinging liquid fuel droplets. However, under conditions
`such as cold-start and warrn-up, the fuel is not vaporized
`through impingement on the relatively cold engine compo-
`ne11ts. Instead, engine operation under these conditions is
`ensured by supplying excess fuel such that a sufficient
`fraction evaporates through heat and mass transfer as it
`travels through the air prior to impinging o11 a cold intake
`component. Evaporation rate through this mechanism is a
`function of fuel properties, temperature, pressure, relative
`droplet and air velocities and droplet diameter. Of course,
`this approach breaks down in extreme ambient cold-starts, in
`which the fuel volatility is insufficient to produce vapor in
`ignitable concentrations with air.
`In order for combustion to be chemically complete, the
`fuel-air mixture must be vaporized to a stoichiometric
`gas-phase mixture. A stoichiometric combustible mixture
`contains the exact quantities of air
`(oxygen) and fuel
`required for complete combustion. For gasoline, this air-fuel
`
`50
`
`60
`
`2
`ratio is about 14.721 by weight. A fuel-air mixture that is not
`completely vaporized, nor stoichiometric, results in inco1n—
`plete combustion and reduced thermal efliciency. The prod-
`ucts of a11 ideal combustion process are water (H20) and
`carbon dioxide (CO2). If combustion is incomplete, some
`carbon is not fully oxidized, yielding carbon monoxide (CO)
`and unburned hydrocarbons
`The mandate to reduce air pollution has resulted in
`attempts to compensate for combustion inefficiencies with a
`multiplicity of fuel system and engine modifications. As
`evidenced by the prior art relating to fuel preparation and
`delivery systems, much effort has been directed to reducing
`liquid fuel droplet size, increasing system turbulence and
`providing sullicient heat to vaporize fuels to permit more
`complete combustion.
`lower engine
`However,
`ineificient fuel preparation at
`temperatures remains a problem which results in higher
`emissions, requiring after-treatment and complex control
`strategies. Such control strategies can include exhaust gas
`recirculation, variable valve timing, retarded ignition timing,
`reduced compression ratios, the use of catalytic co11verters
`and air injection to oxidize unburned hydrocarbons and
`produce an exothermic reaction benefiting catalytic con-
`verter light-off.
`Over-fuelir1g the engine during cold-start and warr11-up is
`a significant source of tmburned hydrocarbon emissions in
`conventional engines. Compounding the problem is the fact
`that the catalytic converter is also cold during this period of
`operation and, thus, does not reduce a significant amount of
`thc unburncd hydrocarbons that pass through the engine
`exhaust. As a result, the high engine-out concentrations of
`ur1burr1ed hydrocarbons pass essentially unreacted through
`the catalytic converter and are emitted from the tailpipe. It
`has been estimated that as much as 80 percent of the total
`hydrocarbon emissions produced by a typical, modern pas-
`senger car occurs during the cold-start and warrn-up period,
`in which the engine is over-fueled and the catalytic converter
`is essentially inactive.
`Given the relatively large proportion of unburned hydro-
`carbons emitted during startup, this aspect of passenger car
`engine operation has been the focus of significant technol-
`ogy development elforts. Furthermore, as increasingly strin-
`gent emissions standards are enacted into legislation and
`consumers remain sensitive to pricing and performance,
`these development efforts will continue to be paramount.
`Such efiorts to reduce start-up emissions from conventional
`engines generally fall into two categories: 1) reducing the
`warrn-up time for three-way catalyst systems and 2) improv-
`ing techniques for fuel vaporization. Elforts to reduce the
`warrn-up time for three-way catalysts to date have included:
`retarding the ignition timing to elevate the exhaust tempera-
`ture; opening the exhaust valves prematurely; electrically
`heating the catalyst; burner or flame heating the catalyst; and
`catalytically heating the catalyst. As a wl1ole, these efforts
`are costly and do not address HC emissions during and
`immediately after cold start.
`A Variety of tecl1r1iques have been proposed to address the
`issue of fuel vaporization. U.S. patents proposing fuel vapor-
`ization techniques include U.S. Pat. No. 5,195,477 issued to
`Hudson, Jr. et al, U.S. Pat. No. 5,331,937 issued to Clarke,
`U.S. Pat. No. 4,886,032 issued to Asmus, U.S. Pat. No.
`4,955,351 issued to Lewis et al., U.S. Pat. No. 4,458,655
`issued to Oza, U.S. Pat. No. 6,189,518 issued to Cooke, US.
`Pat. No. 5,482,023 issued to Hunt, U.S. Pat. No. 6,109,247
`issued to Hunt, U.S. Pat. No. 6,067,970 issued to Awarza-
`mani et al., U.S. Pat. No. 5,947,091 issued to Krohn et al.,
`
`NU MARK Ex.1009 p.24
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`US 7,059,307 B2
`
`3
`U.S. Pat. No. 5,758,826 issued to Nines, U.S. Pat. No.
`5,836,289 issued to Thring, and U.S. Pat. No. 5,813,388
`issued to Cikanek, Jr. et al.
`Other fuel delivery devices proposed include U.S. Pat.
`No. 3,716,416, which discloses a fuel-metering device for
`use in a fuel cell system. The fuel cell system is intended to
`be self-regulating, producing power at a predetermined
`level. The proposed fuel metering system includes a capil-
`lary flow control device for throttling the fuel flow in
`response to the power output of the fuel cell, rather than to
`provide improved fuel preparation for subsequent cor11bus-
`tion. Instead, the fuel is intended to be fed to a fuel reformer
`for co11version to H2 and then fed to a fuel cell. In a preferred
`embodiment, the capillary tubes are made of metal and the
`capillary itself is used as a resistor, which is in electrical
`contact with the power output of the fuel cell. Because the
`flow resistance ofa vapor is greater than that ofa liquid, the
`flow is throttled as the power output increases. The fuels
`suggested for use include any fluid that is easily transformed
`from a liquid to a vapor phase by applying heat and flows
`freely through a capillary. Vaporization appears to be
`achieved in the manner that vapor lock occurs in automotive
`engines.
`US. Pat. No. 6,276,347 proposes a supercritical or near-
`supercritical atomizer and method for achieving atomization
`or vaporization of a liquid. The supercritical atomizer of
`U.S. Pat. No. 6,276,347 is said to enable the use of heavy
`fuels to fire small,
`light weight,
`low compression ratio,
`spark-ignition piston engines that typically bum gasoline.
`The atomizer is intended to create a spray of fine droplets
`from liquid, or liquid-like fuels, by moving the fuels toward
`their supercritical temperature and releasing the fuels into a
`region of lower pressure on the gas stability field in the
`phase diagram associated with the fuels. causing a fine
`atomization or vaporization of the fuel. Utility is disclosed
`for applications such as combustion engines,
`scientific
`equipment, chemical processing, waste disposal control,
`cleaning, etching,
`insect control,
`surface modification,
`humidification and vaporization.
`To minimize decomposition, U.S. Pat. No. 6,276,347
`proposes keeping the fuel below the supercritical tempera-
`ture until passing the distal end of a restrictor for atomiza-
`tion. For certain applications, heating just the tip of the
`restrictor is desired to n1ir1ir11ize the potential for cl1en1ical
`reactions or precipitations. This is said to red11ce problems
`associated with impurities, reactants or materials in the fuel
`stream which otherwise tend to be driven out of solution,
`clogging lines a11d filters. Working at or near supercritical
`prcssurc suggests that tl1c fuel supply system operate in the
`range of 300 to 800 psig. While the use of supercritical
`pressures and temperatures might reduce clogging of the
`atomizer, it appears to require the use of a relatively more
`expensive fuel pump, as well as fuel lines, fittings and the
`like that are capable of operating at these elevated pressures.
`
`OBJECTS AND SUMMARY OF THE
`PREFERRED FORMS
`
`One object is to provide a fuel injector having improved
`fuel vaporization characteristics under all engine operating
`conditions, particularly cold—start and warm-up conditions.
`Another object is to provide a fuel injector capable of
`reducing the ignition energy requirements of a11 inter11al
`combustion engine.
`It is a still further object to provide a fuel injector and
`delivery system capable of reducing emissions and improv-
`ing fuel efficiency.
`
`20
`
`30
`
`4
`It is yet a further object to provide a fuel injector and
`delivery system that can supply vaporized fuel while requir-
`ing minimal power and wann-up time, without the need for
`a high pressure fuel supply system, which may be utilized ir1
`a number of configurations including conventional port-fuel
`injection, hybrid-electric, gasoline direct-injection, and
`alcohol-fueled engines.
`These and other objects will become apparent from the
`detailed description of the preferred forms set out below and
`now summarized as follows:
`A preferred form of the fuel injector for vaporizing a
`liquid fuel for use in an internal combustion engine is
`intended to accomplish at least one or more of the afore-
`mentioned objects. One such form includes at
`least one
`capillary flow passage, the at least one capillary flow pas-
`sage having an inlet end and an outlet end, a fluid control
`valve for placing the inlet end of the at least one capillary
`flow passage in fluid cor11n1ur1icatior1 with the liquid fuel
`source and introducing the liquid fuel in a substantially
`liquid state, a heat source arranged along the at least one
`capillary flow passage, the heat source operable to heat the
`liquid fuel in the at least one capillary flow passage to a level
`sufficient to change at least a portion thereof from the liquid
`state to a vapor state and deliver a stream of substantially
`vaporized fuel from the outlet end of the at
`least one
`capillary flow passage and means for cleaning deposits
`formed during operation of the apparatus. The fuel injector
`is effective in reducing cold—start and warm—up emissions of
`an internal combustion engine. Eflicient combustion is pro-
`moted by forming an aerosol of fine droplet size when the
`substantially vaporized fuel condenses in air. The vaporized
`fuel can be supplied directly or indirectly to a combustion
`chamber of an internal combustion engine during cold—start
`and warm-up of the engine, or at other periods during the
`operation of the engine, and reduced emissions can be
`achieved due to capacity for improved mixture control
`during cold—start, warm-up and transient operation.
`One preferred fonn also provides a method of delivering
`fuel to an internal combustion engine. The method includes
`the steps of supplying liquid fuel to at least one capillary
`flow passage of a fuel injector, causing a stream of substan-
`tially vaporized fuel to pass through an outlet of the at least
`one capillary flow passage by heating the liquid fuel in the
`at
`least one capillary flow passage;
`a11d delivering the
`, vaporized fuel
`to a combustion chamber of the internal
`combustion engine.
`Another preferred form provides a fuel system for use in
`an internal combustion engine, the fuel system including a
`plurality of fuel injectors, cach injcctor including
`at least
`one capillary flow passage, the at least one capillary flow
`passage having an inlet end and an outlet end, (ii) a fluid
`control valve for placing the inlet end of the at least one
`capillary flow passage in fluid communication with the
`liquid fuel source and introducing the liquid fi.1el
`in a
`substantially liquid state and (iii) a heat source arranged
`along the at least one capillary flow passage, the heat source
`operable to heat the liquid fuel in the at least one capillary
`flow passage to a level sufficient to change at least a portion
`thereof from the liquid state to a vapor state and deliver a
`stream of substantially vaporized fuel from the outlet end of
`the at least one capillary flow passage, a liquid fuel supply
`system in fluid communication with the plurality of fuel
`injectors and a controller to control the supply of fuel to the
`plurality of fuel injectors.
`According to one preferred form, the capillary flow pas-
`sage can include a capillary tube and the heat source can
`include a resistance heating eleme11t or a section of the tube
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`US 7,059,307 B2
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`5
`heated by passing electrical current therethrough. The fuel
`supply can be arranged to deliver pressurized or non-
`pressurized liquid fuel to the flow passage. The apparatus
`can provide a stream of vaporized fuel that mixes with air
`and forms an aerosol having a mean droplet size of 25 uni
`or less.
`
`In another preferred form, the mcans for cleaning dcposits
`includes an oxidizer control valve for placing the at least one
`capillary flow passage ir1 fluid cornrnunication with an
`oxidizer, the heat source being operable to heat the oxidizer
`in the at least one capillary flow passage to a level sufficient
`to oxidize deposits formed during the heating of the liquid
`fuel.
`In this embodiment,
`the oxidizer control valve is
`operable to alternate between the introduction of liquid fuel
`and the introduction of oxidizer into the capillary flow
`passage and enable in-situ cleaning of the capillary [low
`passage when the oxidizer is introduced into the at least one
`capillary flow passage. The oxidizer is preferably selected
`from the group of air, exhaust gas, steam and mixtures
`thereof.
`
`tl1e means for cleaning
`In yet another preferred form,
`deposits includes means for abradi11g deposits formed during
`operation of the apparatus. The means for abrading deposits
`can include cleaning brushes disposed along a valve sten1
`positioned within the capillary passage.
`In another preferred form, the means for cleaning deposits
`can include a solvent control valve for placing the at least
`one capillary flow passage in fluid communication with a
`solvent. In this preferred form, the solvent control valve
`alternates between the introduction of liquid fuel a11d the
`introduction of solvent ir1to the capillary flow passage ar1d
`enables in-situ cleaning of the capillary flow passage when
`the solvent is introduced into the at least one capillary flow
`passage.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention will now be described in more detail with
`reference to preferred fonns of the invention, given only by
`way of example. and with reference to the accompanying
`drawings, in which:
`7IG. 1 illustrates a modified fuel injector, in partial cross
`section, which includes a capillary flow passage in accor-
`dance with a preferred form;
`7IG. 2 is a side elevation view of an embodiment of the
`fuel injector according to another preferred form;
`FIG. 2A is ar1 isometric View of mi outlet of the capillary
`of the embodiment illustrated in FIG. 2;
`71G. 3 is a side elevation view of another embodiment of
`a fuel injector according to another preferred form;
`7IG. 3A is an isometric view of another outlet design of
`the capillary of the embodiment illustrated in FIG. 3;
`BIG. 4 is a side elevation view of yet another embodiment
`of a fuel injector according to a preferred form;
`7IG. 4A is an isometric view of another outlet design of
`the capillary of the embodiment illustrated in FIG. 4;
`7IG. 5 is a schematic illustration of still another embodi-
`
`ment of a fuel injector according to a preferred form;
`BIG. 6 is a side view of yet still another embodiment of
`a fuel injector according to a preferred form;
`7IG. 7 is a cross-sectional view of another embodiment of
`the fuel injector according to yet another preferred form;
`FIG. 8 is a side view of another embodiment employing
`dual
`injectors in accordance with still another preferred
`form;
`
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`FIG. 9 is a side view of another embodiment of a fuel
`injector according to a preferred form shown in partial
`cross-section;
`FIG. 9A is an enlarged View of ar1 identified portion of the
`embodiment shown in FIG. 9;
`FIG. 10 is a side view of another embodiment of a fuel
`injector according to a preferred form, shown in partial
`cross-section;
`FIG. 10A is an enlarged view of an idcntificd portion of
`the embodiment shown in FIG. 10;
`FIG. 11 is a side elevation view of yet another preferred
`form of a fuel injector in accordance herewith;
`FIG. 11A is an isometric view of another outlet design of
`the capillary of the embodiment illustrated in FIG. 11;
`FIG. 12 is a side view of another embodiment of a fuel
`injector having a capillary passage heated with recirculated
`exhaust gas;
`FIG. 13 is a schematic of a fuel delivery and control
`system, in accordance with a preferred form;
`FIG. 14 is a chart illustrating engine parameters during the
`first 20 seconds of starting in engine using the fuel delivery
`device of the invention;
`FIG. 15 is a chart illustrating a comparison of engine
`emissions from the fuel delivery device ofthe invention with
`conventional port-fuel injectors;
`FIG. 16 is a graph of gasoline mass flow as a function of
`time showing the benefit to operation achieved through the
`use of the oxidation cleaning method of the present inven-
`tion;
`FIG. 17 is a graph of fuel flow rate vs.
`commercial-grade gasoline;
`FIG. 18 presents a graph of fuel flow rate vs.
`comparing various gasolines;
`FIG. 19 is a graph of fuel flow rate vs. time comparing a
`jet fuel to a No. 2 diesel fuel;
`FIG. 20 presents a graph of fuel flow rate vs. time for an
`unadditized diesel fuel showing the effect of oxidation
`cleaning; and
`FIG. 21 is a graph of fuel flow rate vs. time comparing an
`unadditized diesel fuel to a diesel fuel containing an anti-
`fouling additive.
`
`time for a
`
`time
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`Reference is now r11ade to the embodiments illustrated ir1
`FIGS. 1-21 wherein like numerals are used to designate like
`parts throughout.
`The present invention provides a fuel preparation and
`delivery useful for cold-start, wann-up and normal operation
`of an internal combustion engine. The fuel system includes
`a fuel injector having a capillary flow passage, capable of
`heating liquid fuel so that substantially vaporized fuel is
`supplied into an engine cylinder. The substantially vaporized
`fuel can be combusted with reduced emissions compared to
`conventional fuel injector systems. Furthennore, the fuel
`delivery system of the present invention requires less power,
`and has shorter warm-up times than other vaporization
`techniques.
`low
`In general, gasolines do not readily vaporize at
`temperatures. During the cold start and warm—up period,
`relatively little vaporization of the liquid fuel takes place. As
`such, it is necessary to provide an excess of liquid fuel to
`each cylinder of the engine in order to achieve an air/fuel
`mixture that will combust. Upon ignition of the fuel vapor,
`which is generated from the excess of liquid fuel, combus-
`tion gases discharged from the cylinders include unburned
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`US 7,059,307 B2
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`7
`fuel and undesirable gaseous emissions. However, upon
`reaching normal operating temperature,
`the liquid fuel
`readily vaporizes, so that less fuel is needed to achieve an
`air/fuel mixture that will readily combust. Advantageously,
`upon reaching normal operating temperature,
`the air/f11el
`mixture can be controlled at or near stoichiometry, thereby
`reducing emissions of unburned hydrocarbons and carbon
`monoxide. Additionally, when fi.1eling is controlled at or
`near stoichiomctry, just enough air is available in the exhaust
`stream for simultaneous oxidation of u11bumed hydrocar-
`bons and carbon monoxide and reduction of nitrogen oxides
`over a three-way catalyst (TWC).
`The system and method of the present invention injects
`fuel that has been substantially vaporized into me intake
`flow passage, or directly into an engine cylinder, thereby
`eliminating the need for excess filel during the start-up and
`warm-up period of an engine. The fuel is preferably deliv-
`ered to tl1e engine in a stoichiometric or fuel-lean mixture,
`with air, or air and diluent, so that virtually all of the fuel is
`burned during the cold start and warm-up period.
`With conventional port—fuel
`injection, over—fueling is
`required to ensure robust, quick engine starts. Under fuel-
`rich conditions, the exhaust stream reaching the three-way
`catalyst does not contain enough air to oxidize the excess
`fuel and unbumed hydrocarbons as tl1e catalyst warms up.
`One approach to address this issue is to utilize an air pump
`to supply additional air to the exhaust stream upstream of the
`catalytic converter. The objective is to generate a stoichio-
`metric or slightly fuel-lean exhaust stream which can react
`over the catalyst surface once the catalyst reaches its light-
`off temperature. In contrast, the system and method of the
`present invention enables the engine to operate at stoichio-
`metric or even slightly fuel-lean conditions during the
`cold-start and warm-up period, eliminating botl1 the need for
`over—fueling and the need for an additional exhaust air
`pump, reducing the cost and complexity of the exhaust after
`treatment system.
`As mentioned, during the cold start and warm-11p period,
`the three-way catalyst is initially cold and is not able to
`reduce a significant amount of the unburned hydrocarbons
`that pass through the catalyst. Much effort has been devoted
`to reducing the warm-up time for three-way catalysts, so as
`to convert a larger fraction of the unburned hydrocarbons
`emitted during tl1e cold-start a11d war111-up period. One such
`concept is to deliberately operate the engine very fuel-rich
`during the cold-start and warm-up period. Using an exhaust
`air-pump to supply air i11 this fuel-rich exhaust stream, a
`combustible mixture can be generated which is burned either
`by auto-ignition or by some ignition source upstream of, or
`in, the catalytic converter. The exotherm produced by this
`oxidation process significantly heats up the exhaust gas and
`the heat is largely transferred to the catalytic converter as the
`exhaust passes through tl1e catalyst. Using the system and
`method of the present invention, the engine could be con-
`trolled to operate alternating cylinders fuel-rich a11d fuel-
`lcan to achieve the same effect but witl1out thc nccd for an
`
`air pump. For example, with a four-cylinder engine, two
`cylinders could be operated fuel-ricl1 during tl1e cold-start
`and warm-up period to generate unburned hydrocarbons in
`the exhaust. The two remaining cylinders would be operated
`fuel—lea11 during cold-start and warm-up, to provide oxygen
`in the exhaust stream.
`The system and method of the present invention may also
`be utilized with gasoline direct injection engines (GDI). ln
`GDI engines, the fuel is injected directly into the cylinder as
`a finely atomized spray that evaporates and mixes with air to
`form a premixed charge of air and vaporized fuel prior to
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`ignition. Contemporary GDI engines require high fuel pres-
`sures to atomize tl1e fuel spray. GDI engines operate with
`stratified charge at part load to reduce the pumping losses
`inherent in conventional indirect injected engines. A strati-
`ficd-chargc, spark-ignitcd engine has the potential for bum-
`ing lean mixtures for improved fuel economy and reduced
`emissions. Preferably an overall lean mixture is formed in
`the combustion chamber, but is controlled to be stoichio-
`metric or slightly fuel-rich in the vicinity of the spark plug
`at the time of ignition. The stoichiometric portion is thus
`easily ignited, and this in turn ignites the remaining