Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/0002—Controlling intake air
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/04—Introducing corrections for particular operating conditions
  • F02D41/06—Introducing corrections for particular operating conditions for engine starting or warming up
  • F02D41/062—Introducing corrections for particular operating conditions for engine starting or warming up for starting
  • F02D41/064—Introducing corrections for particular operating conditions for engine starting or warming up for starting at cold start
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/30—Controlling fuel injection
  • F02D41/32—Controlling fuel injection of the low pressure type
  • F02D41/34—Controlling fuel injection of the low pressure type with means for controlling injection timing or duration
  • F02D41/345—Controlling injection timing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/0002—Controlling intake air
  • F02D2041/001—Controlling intake air for engines with variable valve actuation
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2250/00—Engine control related to specific problems or objectives
  • F02D2250/31—Control of the fuel pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2400/00—Control systems adapted for specific engine types; Special features of engine control systems not otherwise provided for; Power supply, connectors or cabling for engine control systems
  • F02D2400/02—Four-stroke combustion engines with electronic control
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/04—Introducing corrections for particular operating conditions
  • F02D41/047—Taking into account fuel evaporation or wall wetting
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/04—Introducing corrections for particular operating conditions
  • F02D41/06—Introducing corrections for particular operating conditions for engine starting or warming up
  • F02D41/061—Introducing corrections for particular operating conditions for engine starting or warming up the corrections being time dependent
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/40—Engine management systems

Definitions

• the invention relates to a process for reducing hydrocarbon emissions from a cold engine with indirect fuel injection.
• FIG. 1 illustrates very schematically the configuration of an indirect fuel injection engine. This figure shows only a single cylinder 1, in partial section of this engine.
• an engine of this type comprises one, two, three or four cylinders or more.
• the cylinder 1 comprises a cylindrical wall 10 allowing a reciprocating vertical movement of a piston 11, surmounted by a combustion chamber 18.
• This chamber is supplied with an "air-fuel” mixture, referenced Airet Ess, respectively, via a conduit
• the indirect injection mode implies that the injector 14 associated with this cylinder sprays the fuel on the walls of the intake duct and / or on the intake valve or valves 15, and not directly. in the combustion chamber 18.
• the engine being of the type called "four-stroke cycle", this mixture is admitted through an intake valve 15 during the so-called admission time.
• the flue gases Ge are ejected in an exhaust duct 13 via an exhaust valve 16, during the exhaust time.
• a spark plug 17 provides sparks for igniting the fuel mixture at the end of the compression time.
• FIG. 1A is a curve showing the variations in the level of unburned hydrocarbon emissions as a function of time, after a first start of the engine, that is to say a cold engine.
• the vertical axis is graduated in ppmC unburned hydrocarbons and the horizontal axis in number of engine cycles.
• a commonly used solution consists in reducing the average diameter of drops injected into the combustion chamber 18, which diameter is characterized by the so-called Sauter average diameter value. This physical quantity is better known by the abbreviation "SMD” used hereafter (for "Sauter Mean Diameter”). To do this, we increase the injection pressure to provide the largest possible exchange surface with the ambient air to vaporize and ensure the most homogeneous mixture possible.
• SMD Stem Mean Diameter
• the Holder has been able to demonstrate that this higher emission of unburnt hydrocarbons from the cold engine in the case of electrically actuated or hydraulic valves finds part of its origin in the fact that the opening of the intake valve performs more quickly with such an electrical control with a conventional cam control, which limits the tearing effect of the fluid film of fuel deposited on the intake ducts: tearing related to the increase of the speeds of gas at low valve openings that allows atomization of fuel drops.
• this tearing effect remains insufficient in the case of a conventional camshaft distribution to limit the discharge of pollutants.
• the Holder in the French patent application No. 0505507, filed on April 5, 2005, proposed a method and a device based on the increase of the fuel intake pressure during the start-up phase. at Engine coolant, applicable for camshaft or electrically or hydraulically operated valves.
• FIGS 2 and 3 placed at the end of the present description can briefly illustrate this process.
• the start of the lift phase of the intake valve 15-15 ' is illustrated when the fuel Ess is sprayed onto the walls of the duct 12 and the air supplied by this air. leads.
• the start-up phase is longer.
• the intake section is narrower, which increases the pressure during this phase.
• the "MDS" of droplets G'punes is lower and the mixture more homogeneous.
• the opening of the intake valve is controlled in two phases: a first phase devoted mainly to the admission of fuel and a second phase devoted mainly to admission of air, the opening of the valve being substantially lower in the first phase than in the second phase, so that the fuel is sprayed in the form of fine droplets during this first phase.
• this process makes it possible to obtain finer droplets and thereby greatly reduce the emission of hydrocarbons, especially when the engine is cold.
• the invention therefore relates to an improved process for reducing hydrocarbon emissions from a cold engine.
• a multiple fuel injection gasoline
• gasoline characterized by at least two distinct injection pressures, namely: an injection called “high pressure” during the so-called “admission time”", the intake valve being open during the first cold engine cycles; and an injection called “low pressure” during the so-called “exhaust” time, the intake valve being closed.
• "low pressure” corresponds in amplitude to a "standard” type of pressure, that is to say of the order of magnitude of that used in engines of the prior art. .
• this mode of operation has the disadvantage of inducing a higher fuel consumption, related to the use of a device increasing the injection pressure. Also, once the engine is warm, it is possible to return to the conventional mode, that is to say in "low pressure” (or standard pressure) injection mode and with closed intake valves.
• the number of high pressure cycles necessary to obtain the desired effect of the invention naturally depends on the particular characteristics of a given engine.
• TVR boiling point of the fuel
• This temperature depends in particular on: the quality of the fuel used - the conditions of pressure and inlet temperature.
• an intermediate phase can be provided during which the transition between the two modes is progressive.
• the amplitude of the fuel injection pressure gradually drops until it reaches the standard pressure.
• fuel is still injected, injection valve open, but it is also possible to make small fuel injections, closed valve, so as to take advantage of the first available calories to vaporize the fuel. Indeed, at this stage, the engine temperature begins to grow strongly, even if it has not yet reached its cruising temperature.
• the subject of the invention is therefore a process for reducing hydrocarbon emissions from a cold engine with indirect fuel injection, said engine operating in a four-stroke cycle, called combustion, exhaust, intake and compression, the engine comprising at least one cylinder provided with at least one intake valve of an air-fuel mixture, characterized in that it comprises at least two successive phases of operation after starting the cold engine:
• each intake valve being fully open; and a second low pressure injection phase during the exhaust time, each intake valve being closed; the second phase being initiated after a determined number of engine cycles.
• FIG. 1 illustrates very schematically the configuration of an indirect fuel injection engine
• FIG. 1A is a curve illustrating the hydrocarbon emission variations as a function of the number of engine cycles, during a cold start
• FIGS. 5A and 5B are curves explaining the fuel injection pressure variations during the phases of the method of the invention.
• Figure 6 schematically illustrates the configuration of an indirect fuel injection engine for the implementation of the method according to the invention.
• Figure 4A illustrates the first phase, referenced I, that is to say during the cold start of the engine.
• FIG. 4A (as well as in FIGS. 4B and 4C), the four operating times of the engine are shown: combustion, exhaust, admission and compression, as well as the so-called “High Death” points ("PM / - /"). ) and “Death Low”("PM? 1 ) successive, corresponding to the positions of the piston 11 ( Figure 1) in the cylinder 10 of the engine 1 during these four times.
• the high-pressure injection period is also referred to as "ppal HP Injection", which can take up almost the entire intake time interval depending on the operating point of the engine.
• phase II is initialized. This phase II is illustrated in Figure 4B.
• injection HP HP injection of fuel
• a so-called “secondary” fuel injection referenced in FIG. 4B "Dry injection” is carried out, the characteristics of which are as follows: it is carried out with a closed intake valve, that is, during the escape time, and it is of relatively short duration. The amplitude of the secondary injection pressure is the same as that of the main pressure.
• the inlet valve may only be partially open and the valve lift gradually decrease from one engine cycle to the next.
• valve lift can typically vary between 0 and 2 mm.
• phase III is initialized. This phase III is illustrated in Figure 4C.
• This phase III is characterized by a so-called “main” fuel injection, at low pressure, referenced “ppal BF injection” in Figure 4C, closed intake valve, that is to say during the exhaust time.
• the duration of the main injection at low pressure can occupy almost the entire interval of the exhaust time, depending on the engine operating point.
• the inlet valve and the ducts are now hot. They reached their "cruising" temperature.
• the engine operates as a conventional engine of the known art.
• the injection pressure may be that implemented in such an engine.
• Figure 5A schematically illustrates the variation of the fuel injection pressure as a function of the number of NCM engine cycles.
• the presence of a first level of constant pressure (high HF pressure) is observed during phase I, then a progressive decrease, a priori linear, during phase II, until reaching a second level of constant pressure (low pressure).
• BF second level of constant pressure
• the high injection pressure is typically greater than or equal to 9 bars (9 10 5 Pascals) and the low injection pressure substantially equal to 3.5 bars.
• the number of NCM engine cycles at high pressure depends on the particular engine considered, the start temperature, the heating conditions of this engine, load conditions thereof after starting.
• an adapted control strategy is implemented taking into account these parameters and making it possible to define the transition moment between operations with a high injection pressure and with a conventional injection pressure.
• a suitable behavior model for a given data engine is determined during its design.
• the method according to the preferred embodiment of the invention comprises three phases, which allows a good optimization.
• phase I phase I
• phase III phase III
• This patent application teaches a method of controlling an internal combustion engine having at least one electrically controlled intake valve, characterized in that, to reduce unburned hydrocarbon emissions from the cold internal combustion engine, the The opening of the valve is controlled in two successive phases, the first phase corresponding mainly to the admission of the fuel and the second phase mainly to the admission of air, the opening of the valve being substantially lower during the first phase. phase than during the second phase so that the fuel is sprayed in the form of fine droplets during this first phase.
• the valve is opened twice during the intake time of the engine, at least one of the openings being controlled in two phases.
• the second opening comprises the two phases, the first phase being performed at low opening, mainly to admit fuel.
• the motor M is assumed to have four cylinders in the example described, 1 a to 1 d.
• Each cylinder (such as the cylinder 1 represented in a dashed box) is similar if not identical to the cylinder shown in FIG.
• the cylinders for example the cylinder 1a, are fed with an "air-gasoline" mixture (references: Airei Ess) via the discharge valve 15.
• the spark plug 17 (FIG. 1) is supplied with electrical energy by a coil 170
• the flue gases Ge are ejected via the exhaust valve 16 to an exhaust pipe 22 - 23.
• a catalyst 8 so as to improve the aftertreatment of the exhaust gas.
• the exhaust pipe, 22 - 23, is usually provided with two oxygen content probes, 80 and 81.
• the engine M comprises a conventional fuel tank 3 equipped with a fuel level sensor 30. Ess gasoline is transported by a pipe 31 to the intake ducts of each cylinder, for example to the intake duct 12 ( figure 1 ).
• the air air is transported by a pipe 90 to be injected into the inlet duct of each cylinder, for example the duct 12 (FIG. 1) of the cylinder 1 a, via an air filter 9 and a motorized butterfly 21, and mixed with fuel Ess.
• An air temperature sensor 20 is usually provided on the air supply.
• the engine M may also include a secondary air pump 7, exhaust side.
• a member 50 called a “canister” and a purge 50, arranged between the air supply line Air and the fuel tank 3.
• a purge 50 arranged between the air supply line Air and the fuel tank 3.
• water temperature sensors. 25, and oil, 26, respectively.
• means are provided for injecting fuel Ess under variable pressure.
• an injection pump (not explicitly shown) provided with two separate gasoline pressure regulators: a low pressure regulator 6a, and a high pressure regulator 6b.
• the injectors for example the injector 14 of the cylinder 1a, are supplied with fuel Ess, under low pressure (especially during phase III: FIG. 4C) or high pressure, respectively (in particular during phase I: FIG. 4A).
• each pump delivers fuel Ess, one under high pressure, the other under low pressure, according to the time diagram of Figures 4A to 4C.
• the amplitude of the pressure can be modulated in time (for example, during phase II: FIG. 4B).
• the measurements made on the motor M using the different sensors are usually processed by an electronic control unit 4, for example a digital computer with a registered program.
• an organ may be, in itself, of a quite conventional type. Only the "hardware" arrangements of electronic circuits and / or programs ("software") must be modified and / or supplemented to implement the method according to the invention.
• the control unit 4 comprises in particular links 41 receiving measurement signals from the various sensors that have been previously described, links 42 enabling analog-to-digital conversions, and actuator control links 40 (not shown).
• various engine members M injectors, for example 14 ( Figure 1), valves, for example 16, etc., which again is conventional in itself.
• the controller 4 generates the control signals 40 of the actuators (for example acting on the pressure regulators, 6a or 6a, so that the injectors (for example FIG. are fed with fuel Ess, low or high pressure, according to a given time diagram ( Figures 4A to 4C), according to the measurement signals from the various sensors, including the number of engine cycles NCM, and measured temperatures.
• phase II the timing diagram of fuel supply of the injectors, the amplitude of the injection pressure, and / or the amplitude of the intake valve lifts, translate by also specific actuator control signals
• the levers of intake valves are also specifically controlled according to a diagram. predefined time. More particularly, the opening of the intake valves is controlled in two successive phases, the first phase corresponding mainly to the intake of fuel Ess and the second phase mainly to the air intake Air, as has been recalled.
• the injection of fuel Ess called the main fuel, that is to say that carried out during the admission time, is carried out at high pressure (phase I: FIG. 4A, and phase II: FIG. 4B).
• the invention achieves the goals it has set for itself. It has many advantages, it makes it possible to achieve a very high reduction of unburned hydrocarbon emissions from a cold engine with indirect injection of gasoline, without requiring significant modifications of the constituent parts of the engine, or to resort to complex and expensive solutions.
• a software solution is used (digital program recorded computer) for the processing of the signals acquired by the sensors and the generation of control signals of the various actuators, the modifications required by the method of the invention are summarized, essentially, an adaptation of the programs implemented in the memory means of the computer.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

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• 2006
  • 2006-07-25 FR FR0653103A patent/FR2904370B1/fr not_active Expired - Fee Related
• 2007
  • 2007-06-15 WO PCT/FR2007/051448 patent/WO2008012452A2/fr active Application Filing
  • 2007-06-15 EP EP07789012A patent/EP2044312A2/de not_active Withdrawn

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