WO1996025593A1 - Procede et dispositif permettant de purifier les gaz d'echappement d'un moteur fonctionnant au gaz naturel - Google Patents

Procede et dispositif permettant de purifier les gaz d'echappement d'un moteur fonctionnant au gaz naturel Download PDF

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Publication number
WO1996025593A1
WO1996025593A1 PCT/JP1995/000209 JP9500209W WO9625593A1 WO 1996025593 A1 WO1996025593 A1 WO 1996025593A1 JP 9500209 W JP9500209 W JP 9500209W WO 9625593 A1 WO9625593 A1 WO 9625593A1
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WO
WIPO (PCT)
Prior art keywords
exhaust gas
air
exhaust
fuel ratio
fuel
Prior art date
Application number
PCT/JP1995/000209
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English (en)
Japanese (ja)
Inventor
Masayoshi Kaneyasu
Nobuo Kurihara
Minoru Ohsuga
Original Assignee
Hitachi, Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi, Ltd. filed Critical Hitachi, Ltd.
Priority to JP08524814A priority Critical patent/JP3009228B2/ja
Priority to PCT/JP1995/000209 priority patent/WO1996025593A1/fr
Publication of WO1996025593A1 publication Critical patent/WO1996025593A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/206—Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/02—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with gaseous fuels
    • F02D19/021—Control of components of the fuel supply system
    • F02D19/023—Control of components of the fuel supply system to adjust the fuel mass or volume flow
    • F02D19/024—Control of components of the fuel supply system to adjust the fuel mass or volume flow by controlling fuel injectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/0015—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for using exhaust gas sensors
    • F02D35/0023—Controlling air supply
    • F02D35/0038—Controlling air supply by means of air pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0203—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels characterised by the type of gaseous fuel
    • F02M21/0215—Mixtures of gaseous fuels; Natural gas; Biogas; Mine gas; Landfill gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2430/00—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
    • F01N2430/06—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics by varying fuel-air ratio, e.g. by enriching fuel-air mixture
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/03—Adding substances to exhaust gases the substance being hydrocarbons, e.g. engine fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0248—Injectors
    • F02M21/0278—Port fuel injectors for single or multipoint injection into the air intake system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • 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
    • Y02T10/12—Improving ICE efficiencies
    • 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
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

Definitions

  • the present invention relates to a method and apparatus for purifying exhaust gas of a natural gas engine.
  • the present invention relates to a method and an apparatus for purifying exhaust gas of a natural gas engine provided with an exhaust gas purification apparatus.
  • a conventional exhaust purification device for an engine uses NOx, which is a reducing gas, and oxidizing gas contained in exhaust gas. HC and C ⁇ were converted independently. Further, the exhaust gas purifying apparatus of a conventional gas engine heat pump mainly reduces N ⁇ X contained in exhaust gas as described in Japanese Patent Application Laid-Open No. 5-220349 (Japanese Patent Application No. 4-287377). For this purpose, hydrocarbons as fuel gas were injected before the catalyst.
  • An object of the first invention is to provide an exhaust purification device capable of converting each exhaust gas of an engine controlled to an arbitrary air-fuel ratio appropriate for an operating state with the highest efficiency.
  • An object of the second invention is to provide an exhaust gas purification method for controlling the gas composition at the inlet of an exhaust gas purification device at high speed and with high precision so as to maximize the conversion efficiency so that the exhaust gas purification performance can be maintained in all operating states.
  • An object of the third invention is to provide a basic control of a fuel supply amount and an ignition timing in an arbitrary operation state, a low water temperature, a lean limit,
  • An object of the present invention is to provide an exhaust gas purifying apparatus that controls a gas composition at an inlet of an exhaust gas purifying apparatus in cooperation with control for suppressing variation in air-fuel ratio of each cylinder.
  • An object of the fourth invention is to supply exhaust purification gas in cooperation with pulsation of exhaust pressure, fluctuation of fuel gas pressure and operation of exhaust gas recirculation so that exhaust purification performance can be maintained with higher accuracy. It is an object of the present invention to provide an exhaust gas purification method for controlling the gas composition at the inlet of the apparatus with high accuracy.
  • a fifth object of the present invention is to provide a device for detecting an abnormality of an exhaust gas purifying gas supply device in order to guarantee an exhaust gas purifying capability.
  • the first invention employs a system in which exhaust gas is supplied so as to promote conversion in the exhaust gas purification device, and a basic control device that determines a fuel supply amount and an ignition timing.
  • a calculation means for calculating the exhaust gas supply amount in cooperation with the normal combustion control is provided.
  • An exhaust gas supply path is provided to control the exhaust gas supply amount independently of the fuel supply amount.
  • an air-fuel ratio sensor that responds to oxygen concentration after the catalyst.
  • An air-fuel ratio sensor may also be provided on the rear side of the exhaust gas purification device.
  • the basic control of the fuel supply amount and the ignition timing, the low fuel temperature, the lean limit, and the air-fuel ratio variation for each cylinder are suppressed without any additional components.
  • the exhaust gas purifying gas supply amount is controlled simultaneously with the basic control calculation inside the engine control device that performs such control.
  • the exhaust purifying gas supply is performed in synchronization with the exhaust pressure pulsation, the fuel gas pressure fluctuation, and the exhaust gas recirculation operation without particularly adding components.
  • an air-fuel ratio sensor is provided on the rear side of the exhaust gas purification device.
  • the following operation and effect can be obtained.
  • the air-fuel ratio after the catalyst can be measured by the air-fuel ratio sensor, so that the required amount of exhaust gas to be purified can be calculated strictly.
  • the third invention can recognize basic control of the fuel supply amount and the ignition timing in an arbitrary operation state, control for suppressing the variation of the air-fuel ratio at low water temperature, lean limit, and each cylinder, and the like.
  • the supply amount can be calculated exactly.
  • the pulsation of the exhaust gas pressure, the fluctuation of the fuel gas pressure, and the operation of the exhaust gas recirculation can be recognized, so that the supply time of the exhaust gas can be determined strictly.
  • the abnormality of the exhaust gas purifying gas supply device can be detected from the signal of the air-fuel ratio sensor, so that the exhaust gas purifying ability can be guaranteed.
  • FIG. 1 is a system diagram of a natural gas engine.
  • Figure 2 shows the composition of natural gas exhaust gas.
  • Figure 3 shows the exhaust gas conversion efficiency of the Pt ZRh-based catalyst.
  • FIG. 4 is a diagram showing the exhaust gas conversion efficiency of a Pd-based catalyst.
  • FIG. 5 is a flowchart for determining the exhaust gas purifying gas supply amount and the fuel injection amount extinction from the basic fuel injection amount and ignition timing.
  • FIG. 6 is a flowchart for determining an increase / decrease in the amount of exhaust gas supply when an exhaust gas supply path is provided.
  • FIG. 7 is a diagram showing an exhaust system provided with a NOX reduction catalyst and a three-way catalyst.
  • FIG. 8 is a flowchart for determining the supply amount of exhaust purification gas when an N ⁇ X reduction catalyst is provided.
  • FIG. 9 is a diagram showing an exhaust system provided with an N ⁇ X reduction catalyst and a three-way catalyst and further provided with an oxygen supply means.
  • FIG. 10 is a flowchart for determining the supply amount of exhaust gas when the oxygen supply means is provided.
  • FIG. 11 is a control system diagram of an exhaust gas purification gas supply amount using a second air-fuel ratio sensor.
  • FIG. 12 is a flowchart for determining the exhaust gas purification gas supply amount by the second air-fuel ratio sensor.
  • FIG. 13 is a flowchart for determining an exhaust gas supply gas amount from a fuel injection amount determined from a cooling water temperature. Fig.
  • FIG. 14 is a chart showing the relationship between the lean limit, which is determined by the vibration intensity of the engine and the crank rotation fluctuation.
  • FIG. 15 is a flowchart for determining the exhaust gas supply amount from the fuel injection amount and the ignition timing obtained by determining the air-fuel ratio for each cylinder from the crank rotation fluctuation.
  • FIG. 16 is a timing chart showing a flag for permitting the supply of exhaust gas to the fuel injection amount increase / decrease coefficient, so-called lambda coefficient.
  • FIG. 17 is a flowchart for determining an increase / decrease of an exhaust gas supply amount and a fuel injection amount from a deviation of an exhaust air-fuel ratio from a target value.
  • FIG. 15 is a flowchart for determining the exhaust gas supply amount from the fuel injection amount and the ignition timing obtained by determining the air-fuel ratio for each cylinder from the crank rotation fluctuation.
  • FIG. 16 is a timing chart showing a flag for permitting the supply of exhaust gas to the fuel injection amount increase / decrease coefficient, so-called lambd
  • FIG. 18 is a timing diagram showing a flag for permitting the supply of exhaust gas purifying gas with respect to a change in exhaust pipe pressure.
  • FIG. 19 is a timing chart showing flags that allow the supply of exhaust gas to the fuel injection signal.
  • FIGS. 20 (a) and (b) are timing diagrams showing a flag for permitting the supply of exhaust gas to the duty ratio of the opening and closing of the EGR valve.
  • Fig. 2 1 shows the case when an abnormality occurs in the exhaust gas
  • FIG. 8 is a timing chart showing an output of a second air-fuel ratio sensor.
  • FIG. 22 is a flowchart for judging abnormality of the exhaust gas purification device from the signal of the second air-fuel ratio sensor.
  • FIG. 1 is a system configuration diagram. After passing through the slot cleaner 11 through the air cleaner and duct, the air is drawn into the engine cylinder through the intake pipe. The intake air amount is detected by an intake air flow sensor 12 provided upstream of the slot solenoid 11, and a detection signal is input to the engine control device 10.
  • the fuel is guided from a fuel cylinder (not shown), the pressure of which is measured by a fuel gas pressure sensor 5, and then supplied to an intake pipe via a fuel gas supply device 4, mixed with intake air and supplied to an engine cylinder. Is done.
  • the air-fuel mixture is compressed by the engine, ignited by the spark plug 16 and the exhaust gas after explosion is discharged from the exhaust pipe.
  • An air-fuel ratio sensor 14 is provided in the exhaust pipe, and a detection signal is input to the engine controller 10.
  • the engine exhaust is purified and discharged by the three-way catalyst 3.
  • the flow rate of the fuel gas is separately adjusted by the exhaust gas purifying gas flow controller 2, supplied into the exhaust pipe from the exhaust gas purifying gas supply path 1, mixed with the exhaust gas, and guided to the three-way catalyst 3.
  • the rotational speed of the engine is detected by a crank rotation sensor 13, the throttle opening is detected by a throttle opening sensor 20, and the temperature of the cooling water is detected by a water temperature sensor 17. Input to 10.
  • a vibration sensor 15 for detecting vibration is attached to the engine, and a detection signal is input to the engine control device 10.
  • the engine control device 10 determines the fuel supply amount based on the signal from each sensor, Calculates the ignition timing, ISC valve control signal, EGR valve control signal, etc., and outputs control signals to each actuator such as the fuel gas supply device 4, spark plug 16, ISC valve 18 and EGR valve 19, etc.
  • the features of the present invention are best represented by the exhaust gas supply path 1.
  • the fuel gas may be introduced into this supply path and may be appropriately reduced in pressure before reaching the fuel gas pressure sensor 5. Based on the measurement result by the fuel gas pressure sensor 5, the width or amount of supply or stoppage in the fuel gas supply device 4 is corrected.
  • the fuel gas is introduced into the exhaust gas supply path 1.
  • the fuel gas is not limited to the fuel gas, but may be a hydrocarbon gas or the like having a property capable of mainly reducing N ⁇ X.
  • the amount of gas supplied to the exhaust pipe through the exhaust gas supply path 1 is controlled by an exhaust gas flow controller 2 to control the gas composition in the exhaust gas such as HC, CO, and N ⁇ X. Care should be taken to balance and convert the exhaust gas in the three-way catalyst without excess or shortage.
  • the main purpose of supplying exhaust gas is to convert exhaust gases such as HC, CO, and Nx in a balanced manner in engines that use natural gas as fuel.
  • the engine exhaust H C and N ⁇ x are as shown in Fig. 2 at the air-fuel ratio near the stoichiometry.
  • the quantity is smaller than that of the gasoline engine, the characteristics of HC gradually decrease and NOx rapidly increase as the air-fuel ratio shifts from the stoichiometric to the lean side are the same.
  • the conversion efficiency of the three-way catalyst is as shown in Fig. 3 for the Pt ZRh-based catalyst and Fig. 4 for the Pd-based catalyst, and the conversion efficiency of HC and N ⁇ X on the lean side is low. As a result, HC and N ⁇ X are emitted in large quantities.
  • the key point of the present invention is to make the exhaust gas guided to the three-way catalyst a little richer, and to set the air-fuel ratio with high conversion efficiency of HC and NOx to achieve the highest efficiency of exhaust gas conversion in the three-way catalyst. To make it happen. That is, as shown in Figs. 3 and 4, the target value of the air-fuel ratio at the inlet of the three-way catalyst is 0.99 to 1.00 (range 31) for the PtZRh-based catalyst. For Pd-based catalysts, the highest conversion efficiency can be obtained by setting the range from 0.985 to 0.995 (range 41).
  • a first aspect of the present invention resides in that the air-fuel ratio at the inlet of the three-way catalyst is manipulated in the same manner as the essential point of the invention.
  • the first is to control the air-fuel ratio in the cylinder to a desired value
  • the second is to burn it in the cylinder with a stoichiometric cylinder and, for example, to provide carbonization at the inlet of the three-way catalyst.
  • This is a method in which exhaust gas having a desired air-fuel ratio is supplied to the three-way catalyst by supplying hydrogen gas.
  • the engine speed is detected 5 1 by the crank rotation sensor 13, and the intake air flow rate Qa is detected 5 2 by the intake air flow sensor 12 2.
  • the basic fuel injection amount is calculated based on the engine speed and the intake air flow rate.
  • Calculation 53 is performed on Ti, and at the same time, calculation 54 is also performed on the basic ignition timing AdV. In normal engine control, if these Ti and AdV can be determined appropriately, the engine can be operated smoothly. Where T i and A dv are in the steady state g
  • the supply amount of the exhaust gas purifying gas is calculated based on the Ti and Adv.
  • the fuel injection amount including the exhaust gas supply amount is 1 * 1 of Ti.
  • ⁇ * is determined in the range 31 or 41 of the target value of the air-fuel ratio.
  • the ignition timing also determines the correction ignition timing A dv * 57 from the basic ignition timing A d V according to the fuel increase.
  • the total fuel injection amount T i * and the correction ignition timing A d V * are set in the memory as final values 58, 59, and the actual fuel injection and ignition operation is executed in a timely manner according to these memory values.
  • c The arithmetic processing in the second method will be described with reference to the flowchart of FIG.
  • the engine speed detection 51 and the intake air flow rate detection 52 are the same as in FIG. 5, and the calculation of the basic fuel injection amount T i based on the engine speed and the intake air flow rate 53 and the calculation of the basic ignition timing A dv The same is true for 54.
  • the subsequent processing is different from that of Fig. 5 and these Ti and Adv are set in the memory as final values as in normal engine control.
  • the exhaust purifying gas supply coefficient k is determined 5 5
  • the exhaust purifying gas supply amount T rg * is calculated by multiplying the basic fuel injection amount T i by k 6 3: this exhaust purifying gas supply amount T rg *
  • the basic fuel injection amount T i is effective, that is, the fuel is injected based on T i, the fuel is burned in the cylinder, and the exhaust gas reaches the inlet of the three-way catalyst when the exhaust gas is purified. Is performed after the delay processing 64 is supplied so as to be supplied. In this method, the ignition timing A dv is not corrected.
  • the required exhaust gas supply gas can be calculated in a foreseeable manner.
  • N ⁇ X reducing catalyst is required because most of the exhaust components in lean combustion are N ⁇ X. Because of this large variation in exhaust gas composition, even with the present invention, exhaust purification cannot be performed using only a three-way catalyst. Therefore, as shown in Fig. 7, the N ⁇ x reduction catalyst 71 and the three-way catalyst 3 are arranged in this order, and after supplying exhaust purification gas, most of the N ⁇ x is removed by the preceding N 0 X reduction catalyst 71. Then, the remaining three-way catalyst 3 purifies the remaining exhaust gas.
  • the exhaust purification gas supplied as in the present invention replaces this.
  • the exhaust purifying gas supply amount is adjusted by the exhaust purifying gas flow controller 2 so that the purification in the three-way catalyst 3 becomes highly efficient, and is guided to the three-way catalyst 3 via the NOX reducing catalyst 7 1 and the exhaust gas composition. Balance.
  • Engine speed detection 51 and intake air flow rate detection 52 are the same as in FIG. 5, and a target air-fuel ratio at the time of lean burn is calculated 83 based on the engine speed and intake air flow rate 83.
  • the basic fuel injection amount T i is calculated and set in the memory 84.
  • the basic ignition timing Ad V is also calculated and set in the memory 85.
  • the exhaust purification gas supply coefficient (particularly k NC ) is different from that in Fig. 5, so that the purification in the three-way catalyst 3 is highly efficient, that is, the air-fuel ratio is predetermined at the inlet of the NOX reduction catalyst 71.
  • the supply amount T rg NC of the exhaust purification gas is calculated by multiplying the basic fuel injection amount T i by k NC .
  • the basic fuel injection amount T i is effective, ie, the fuel is injected based on T i, the fuel is burned in the cylinder, and the exhaust gas reaches the inlet of the three-way catalyst. Is performed after the delay processing 64 so that is supplied. In this method as well, the ignition timing A d V is not corrected as in Fig. 6.
  • an oxygen supply means 92 for injecting oxygen or air is provided between the N ⁇ x reduction catalyst 71 and the three-way catalyst 3 as shown in Fig. 9, and the exhaust gas purification gas flow rate is controlled by the engine control device 10.
  • the composition of the exhaust gas led to the three-way catalyst 3 via the N ⁇ x reduction catalyst 71 1 is controlled so that the purification in the three-way catalyst 3 becomes highly efficient.
  • the control method of the oxygen supply means 92 will be described with reference to the flowchart of FIG.
  • the supply amount of exhaust purification gas T rg NC is set in the same manner as in FIG.
  • the oxygen supply amount T aa in this case is calculated by multiplying the intake air flow rate Q a by h air and multiplying by the conversion coefficient ⁇ between the valve opening time in the oxygen supply means 92 and the actual amount of oxygen flowing 102. .
  • the setting 104 of the oxygen supply amount Taa in the memory is performed after the delay processing 103 so that the oxygen gas is supplied at the time when the basic fuel injection amount Ti becomes effective as described above. .
  • the air-fuel ratio at the inlet of the NOx reduction catalyst can be appropriately recognized for an arbitrary operating state, so that it is not necessary.
  • oxygen can be supplied such that the purification efficiency of the ternary catalyst 3 is maximized.
  • a second aspect of the invention is to supply an exhaust gas purifying gas by measuring an air-fuel ratio in an exhaust pipe.
  • the catalyst as shown in Fig. 11 is used.
  • a second air-fuel ratio sensor 1 1 1 is placed on the rear side of 1 1 2 to adjust the exhaust gas composition after the catalyst to a desired state, and the amount of exhaust gas supplied so that the exhaust gas purification at the catalyst becomes the highest efficiency. If exhaust gas purification can be controlled in a closed loop, more complete exhaust gas purification can be realized.
  • the supply amount of the exhaust gas is determined according to the signal of the second air-fuel ratio sensor after the catalyst.
  • the air-fuel ratio after the catalyst can be recognized with respect to an arbitrary operating state. Can be calculated exactly.
  • the third invention recognizes the basic control of the fuel supply amount and the ignition timing in an arbitrary operation state, the control for suppressing the variation of the air-fuel ratio at low water temperature, at the time of lean limit, and for each cylinder, and the like. The point is to calculate the amount exactly.
  • the method of recognizing the control variables related to basic control such as the fuel supply amount and the ignition timing and accurately calculating the exhaust gas supply amount has already been described in FIGS. 5 and 6.
  • the exhaust gas purification gas supply amount is not limited to the fuel supply amount and ignition timing control, but is corrected at startup, idle correction, water temperature correction, shift correction, air conditioner correction, acceleration correction, destruction.
  • the optimal values are set in tandem with the effects of various correction values such as speed correction, restart correction, fuel cut, and fuel cut return correction.
  • a method of calculating the exhaust gas supply amount will be described by taking as an example the case of low temperature start, lean limit, and cylinder-by-cylinder air-fuel ratio control.
  • the fuel supply amount is set higher than usual. Calculation 13 is performed to reduce or stop the fuel supply according to the supplied fuel supply amount.
  • the vibration sensor 15 or the crank rotation sensor 13 detects the vibration intensity or rotation fluctuation 14 1 and determines that the engine is at the lean limit. Is defined as being increased from the previous amount. At this time, the calculation 144 is performed so that the exhaust purified gas supply amount is reduced according to the increased fuel supply amount. Conversely, in the case before the lean limit at which the control for decreasing the fuel supply is performed, the exhaust purification gas supply is increased according to the small amount of the fuel supply.
  • Certain cylinders are set so that torque is smoothed. Since the air-fuel ratio for each cylinder is not always constant because the output torque is smoothed, the supply amount of exhaust gas is calculated according to the increase or decrease of the fuel supply amount. According to the method described with reference to FIGS. 13 to 15, it is possible to recognize the mode of air-fuel ratio control and the amount of fuel supply at low water temperature, lean limit, and for each cylinder. Can be calculated.
  • a fourth aspect of the invention resides in that the supply timing of the exhaust gas is determined in a timely manner by recognizing the pulsation of the exhaust pressure, the fluctuation of the fuel gas pressure, and the dynamic behavior of the engine such as the exhaust gas recirculation.
  • the supply of the exhaust gas is performed only at the time permitted by the exhaust gas supply permission flag.
  • Fig. 16 shows a well-known form of air-fuel ratio feedback control using an oxygen sensor.
  • the fuel injection amount increase / decrease coefficient 1 62 depends on the signal from the oxygen sensor and the fuel is controlled when the exhaust air-fuel ratio is rich.
  • the injection amount is gradually reduced, and conversely, it is gradually increased at the time of leaning. Since the function of the present invention is to bring the air-fuel ratio before the catalyst to a slightly rich desired state, during this air-fuel ratio feedback control, the exhaust gas is supplied only when the exhaust air-fuel ratio is lean.
  • An exhaust purifying gas supply permission flag 161 is provided so that the supply timing of exhaust purifying gas can be determined in a timely manner.
  • FIG. 17 shows a processing flow for a system having a wide-range air-fuel ratio sensor instead of an oxygen sensor.
  • the exhaust purifying gas supply amount is calculated 176 and set 177 according to the fuel injection amount, and these operations are permitted or prohibited 175 according to the exhaust purifying gas supply permission flag described above.
  • FIG. 18 shows an example in which the supply efficiency of exhaust gas is improved by setting the exhaust gas supply permission flag 161 to the permitted side and supplying the exhaust gas at a time when the differential pressure is large according to the low pressure of the exhaust pipe pressure 182. Is shown.
  • Fig. 19 shows the case where fuel gas is used as the exhaust purification gas, and the exhaust purification gas is supplied at the time when the fuel pressure immediately before the effective fuel injection 192 is a regular value that is not disturbed by the fuel injection.
  • the exhaust gas supply permission flag 161 is set to the permission side so that the supply amount can be easily controlled.
  • Fig. 20 (a) shows the response to the duty operation of the EGR valve 19 that controls the amount of exhaust gas recirculation, and if the average value of the duty ratio is larger than the predetermined value 201, 202
  • An example is shown in which the exhaust gas purification efficiency is improved by setting the exhaust gas supply permission flag 161 to the permissible side when the exhaust pipe pressure becomes high while the duty ratio is small to prevent the backflow of the exhaust gas.
  • FIG. 20 (b) when the average value of the duty ratio is smaller than the predetermined value 201, 203, conversely, when the duty ratio at which the exhaust pipe pressure becomes low is large, the exhaust
  • the purification gas supply permission flag 16 1 is set to the permission side to improve exhaust gas purification efficiency.
  • the supply timing of the exhaust purification gas can be determined strictly.
  • a fifth aspect of the present invention is to detect an abnormality of the exhaust gas supply device from a signal of an air-fuel ratio sensor provided after the catalyst.
  • Fig. 21 shows a system in which the second air-fuel ratio sensor 11 1 is arranged behind the catalyst 11 2 as shown in Fig. 11 in the case where an abnormality occurs in the exhaust gas purification device. This shows the output of the rear air-fuel ratio sensor 1 1 1.
  • the signal of the air-fuel ratio sensor 14 before the catalyst is used. ⁇ 5
  • the fuel injection amount increase / decrease coefficient is operated as 2 2 1.
  • the output of the air-fuel ratio sensor 11 1 after the catalyst is lean as shown in 2 4 because the exhaust gas has been added. I can't be in a state.
  • an abnormality occurs in the exhaust gas purifying gas supply device, only a smaller amount of exhaust gas is supplied than is required, and the output of the air-fuel ratio sensor after catalyst 111 is smaller than the normal value. Thus, a lean state appears.
  • FIG. 22 shows a flowchart for detecting an abnormality of the exhaust gas purification device from the signals of the air-fuel ratio sensors provided before and after the catalyst.
  • the signal of the air-fuel ratio sensor provided before and after the catalyst is detected 2201, and the previous value a of the fuel injection amount increase / decrease coefficient is obtained.
  • the above-described time measurement processing 2 2 3 2 or 2233 is executed.
  • the duration T FIAN of the lean state before the catalyst is recorded, and the time measurement buffer TF is initialized 2 2 1 1.
  • More than Time interval signal of the air-fuel ratio sensor provided in the precatalyst is Ritsuchi by time measurement and processing of the buffer time interval is lean in T Fr i ch is recorded in T Fl ean, also the air-fuel ratio sensor after the catalyst signal rich, respectively during the interval when a lean T Rri ch, is recorded in T Rl ean. Therefore, the recording of these time intervals and the abnormality determination program described below are updated every cycle in which the signal of the air-fuel ratio sensor before the catalyst becomes rich and lean.
  • an abnormality of the exhaust gas purifying gas supply device can be detected from the signal of the air-fuel ratio sensor, so that the exhaust gas purifying ability can be guaranteed.
  • the first invention can always recognize the air-fuel ratio that is appropriate for an arbitrary operating state, and thus can predictably calculate the required amount of exhaust gas to be supplied. j ⁇
  • the air-fuel ratio at the inlet of the N ⁇ x reduction catalyst can be appropriately recognized for any operation state, so that the required exhaust gas purification gas supply amount can be calculated in a foreseeable manner.
  • Oxygen can be supplied to maximize purification efficiency.
  • the third aspect of the invention can recognize the mode of air-fuel ratio control at low water temperature, at the time of lean limit, and for each cylinder, so that the exhaust gas purification gas supply amount can be calculated exactly.
  • the dynamic behavior of the engine such as the pulsation of the exhaust pressure, the fluctuation of the fuel gas pressure, and the operation of the exhaust gas recirculation can be recognized, so that the supply timing of the exhaust gas can be determined strictly.
  • the exhaust gas purifying ability can be guaranteed.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

Un système amène un gaz de purification d'échappement en amont d'un convertisseur catalytique à trois voies (3) pour y faciliter la conversion, et un dispositif de calcul, qui calcule le volume de ce gaz de purification d'échappement en coopération avec une commande de combustion normale, est intégré à un dispositif de commande (10) de moteur pour déterminer un volume de combustible et un réglage d'allumage. On prévoit en outre un conduit d'amenée (1) de gaz de purification d'échappement pour commander le volume de ce gaz indépendemment du volume d'alimentation en carburant. En plus, un capteur de rapport air/combustible (111) peut aussi être disposé en aval du convertisseur catalytique pour commander par rétroaction le volume du gaz de purification d'échappement. La commande de volume de ce gaz est synchrone avec des calculs de commande de base régissant par exemple le volume de combustible et le réglage d'allumage ainsi que la variation du rapport air/combustible, quand la température de l'eau de refroidissement est basse, quand on atteint la limite d'un mélange pauvre, et entre les cylindres. Comme un rapport air/combustible considéré comme approprié à toutes les conditions de fonctionnement est identifié en permanence, le volume nécessaire d e gaz de purification d'échappement peut être estimé, ce qui maximise l'efficacité de purification du convertisseur à trois voies. Ainsi, la combustion intervient à un rapport de mélange optimum, les gaz d'échappement traversant le convertisseur catalytique sont commandés selon un rapport de mélange optimum en matière de purification, et on obtient à la fois un rendement du moteur et une efficacité de purification des gaz d'échappement qui sont améliorés.
PCT/JP1995/000209 1995-02-15 1995-02-15 Procede et dispositif permettant de purifier les gaz d'echappement d'un moteur fonctionnant au gaz naturel WO1996025593A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP08524814A JP3009228B2 (ja) 1995-02-15 1995-02-15 天然ガスエンジンの排気浄化方法及び装置
PCT/JP1995/000209 WO1996025593A1 (fr) 1995-02-15 1995-02-15 Procede et dispositif permettant de purifier les gaz d'echappement d'un moteur fonctionnant au gaz naturel

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PCT/JP1995/000209 WO1996025593A1 (fr) 1995-02-15 1995-02-15 Procede et dispositif permettant de purifier les gaz d'echappement d'un moteur fonctionnant au gaz naturel

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006181569A (ja) * 2004-12-01 2006-07-13 Osaka Gas Co Ltd 三元触媒及びこれを用いたメタン含有ガスの浄化方法
JP2011162372A (ja) * 2010-02-05 2011-08-25 Honda Motor Co Ltd 水素製造システム
WO2018054490A1 (fr) * 2016-09-23 2018-03-29 Volvo Truck Corporation Système de moteur à combustion interne

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JPS49101727A (fr) * 1973-02-05 1974-09-26
JPS5539339U (fr) * 1978-09-04 1980-03-13
JPS5799228A (en) * 1980-12-11 1982-06-19 Toyota Motor Corp Exhaust gas purifier of internal combustion engine
JPS62251415A (ja) * 1986-04-23 1987-11-02 Toyota Motor Corp 内燃機関の排ガス浄化装置
JPS63306246A (ja) * 1987-06-05 1988-12-14 Nissan Motor Co Ltd 内燃機関の空燃比制御装置
JPS64312A (en) * 1987-06-22 1989-01-05 Yanmar Diesel Engine Co Ltd Spark-ignition engine with catalizer
JPH0227132A (ja) * 1988-07-14 1990-01-29 Japan Electron Control Syst Co Ltd 内燃機関の空燃比制御装置
JPH04298659A (ja) * 1991-03-27 1992-10-22 Osaka Gas Co Ltd 排ガス浄化装置及びその空燃比制御方法
JPH04365919A (ja) * 1991-06-11 1992-12-17 Mazda Motor Corp 二次空気供給装置の故障診断装置
JPH0666185A (ja) * 1992-08-11 1994-03-08 Toyota Motor Corp 内燃機関の排気浄化装置
JPH06264821A (ja) * 1993-03-10 1994-09-20 Nissan Motor Co Ltd Ｃｎｇエンジンの燃料供給装置

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Publication number Priority date Publication date Assignee Title
JPS49101727A (fr) * 1973-02-05 1974-09-26
JPS5539339U (fr) * 1978-09-04 1980-03-13
JPS5799228A (en) * 1980-12-11 1982-06-19 Toyota Motor Corp Exhaust gas purifier of internal combustion engine
JPS62251415A (ja) * 1986-04-23 1987-11-02 Toyota Motor Corp 内燃機関の排ガス浄化装置
JPS63306246A (ja) * 1987-06-05 1988-12-14 Nissan Motor Co Ltd 内燃機関の空燃比制御装置
JPS64312A (en) * 1987-06-22 1989-01-05 Yanmar Diesel Engine Co Ltd Spark-ignition engine with catalizer
JPH0227132A (ja) * 1988-07-14 1990-01-29 Japan Electron Control Syst Co Ltd 内燃機関の空燃比制御装置
JPH04298659A (ja) * 1991-03-27 1992-10-22 Osaka Gas Co Ltd 排ガス浄化装置及びその空燃比制御方法
JPH04365919A (ja) * 1991-06-11 1992-12-17 Mazda Motor Corp 二次空気供給装置の故障診断装置
JPH0666185A (ja) * 1992-08-11 1994-03-08 Toyota Motor Corp 内燃機関の排気浄化装置
JPH06264821A (ja) * 1993-03-10 1994-09-20 Nissan Motor Co Ltd Ｃｎｇエンジンの燃料供給装置

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006181569A (ja) * 2004-12-01 2006-07-13 Osaka Gas Co Ltd 三元触媒及びこれを用いたメタン含有ガスの浄化方法
JP4688646B2 (ja) * 2004-12-01 2011-05-25 大阪瓦斯株式会社 三元触媒及びこれを用いたメタン含有ガスの浄化方法
JP2011162372A (ja) * 2010-02-05 2011-08-25 Honda Motor Co Ltd 水素製造システム
WO2018054490A1 (fr) * 2016-09-23 2018-03-29 Volvo Truck Corporation Système de moteur à combustion interne

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