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GB2316338A - An emission control system for an engine - Google Patents

An emission control system for an engine Download PDF

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Publication number
GB2316338A
GB2316338A GB9617548A GB9617548A GB2316338A GB 2316338 A GB2316338 A GB 2316338A GB 9617548 A GB9617548 A GB 9617548A GB 9617548 A GB9617548 A GB 9617548A GB 2316338 A GB2316338 A GB 2316338A
Authority
GB
United Kingdom
Prior art keywords
control system
emission control
exhaust gas
catalytic converter
engine
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
GB9617548A
Other versions
GB9617548D0 (en
Inventor
Jake Douglas Mcnair Walker
John Christopher Ruddy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
MG Rover Group Ltd
Original Assignee
MG Rover Group 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 MG Rover Group Ltd filed Critical MG Rover Group Ltd
Priority to GB9617548A priority Critical patent/GB2316338A/en
Publication of GB9617548D0 publication Critical patent/GB9617548D0/en
Publication of GB2316338A publication Critical patent/GB2316338A/en
Withdrawn legal-status Critical Current

Links

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
    • F02D41/008—Controlling each cylinder individually
    • F02D41/0082—Controlling each cylinder individually per groups or banks
    • 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
    • F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
    • 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
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/024—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus
    • F02D41/025—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus by changing the composition of the exhaust gas, e.g. for exothermic reaction on exhaust gas treating apparatus
    • 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
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • 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

Landscapes

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

Abstract

An emission control system for a motor vehicle is disclosed in which an engine management system 16 operates two cylinders 10a, 10b rich of a stoichiometric ratio and two cylinders 10c, 10d lean of a stoichiometric ratio during the warm-up period of the engine 10. This provides excess fuel and air entering the catalytic converter 19 which can be burnt to provide extra heating of the catalytic converter 19 and thus reduce the time taken for the converter 19 to reach a 50% conversion efficiency.

Description

An Emission control System for an Engine This invention relates to emission control systems and in particular to an emission control system for an engine of a motor vehicle.
It is known to provide the engine of a motor vehicle with a catalytic converter to reduce exhaust gas emissions.
A conventional catalytic converter achieves only a low conversion efficiency (e.g. < 10%) until it reaches a light-off temperature in the order of 2500 C by self heating from the exhaust gasses. The exhaust gas emissions below 2500 C, i.e. during warm-up, are therefore of a major detriment to the overall emissions performance of the motor vehicle.
It is an object of this invention to provide an improved emission control system for a motor vehicle.
According to the invention there is provided an emission control system for a motor vehicle including a multi-cylinder internal combustion engine, the emission control system comprising a fuelling means arranged to control the introduction of a combustible mixture into each cylinder of the engine, an exhaust system arranged to carry an exhaust gas from the engine and a catalytic converter included in the exhaust system wherein the fuelling means is arranged to control the exhaust gas entering the catalytic converter such that the exhaust gas contains a combustible mixture for part of the engine operating cycle.
The part of the operating cycle may commence when the catalytic converter is below a predetermined operating temperature range and the combustible mixture in the exhaust gas is burnt in the catalytic converter to heat the catalytic converter up to the predetermined operating temperature range.
The part of the operating cycle may commence after the engine has been started or after a period during which the engine is operated at low speed for a predetermined period.
The fuelling means may arrange the combustible mixture to be present in the exhaust gas by operating at least one cylinder rich of a stoichiometric air-fuel ratio and at least one cylinder lean of a stoichiometric air-fuel ratio.
The predetermined operating temperature of the catalytic converter may be in the order of 250 0C to 350 C and the combustible mixture may be present in the exhaust gas only when the catalytic converter temperature is in the order of 2000C to 350 C.
The operating temperature of the catalytic converter may be reduced by the burning of said combustible mixture in the catalytic converter and said operating temperature may be reduced to the order of 220 0C to 230 C.
The inlet manifold 11 includes a fuel injector 13a, 13b, 13c, 13d in each inlet tract under the control of an engine management system (EMS) 16 and has a throttle butterfly 14 positioned at the inlet to a plenum chamber lla. The throttle butterfly 14 is driven bi-directionally by a motor 15 which is also under the control of the EMS 16.
The exhaust manifold 12 is connected to an exhaust down-pipe 17 which in turn is connected to a catalytic converter 19 forming part of an exhaust system 20.
An exhaust gas oxygen sensor 18 is included in the down-pipe 17 and is connected to the EMS 16.
The EMS 16 controls the volume of air entering the plenum chamber lla by opening and closing the throttle butterfly 14 with the motor 15 and controls the quantity of fuel injected into each inlet tract by controlling the injectors 13a, 13b, 13c, 13d individually. In this manner, the EMS 16 controls the air-fuel ratio of the mixture entering each cylinder l0a, lOb, lOc, lOd.
The exhaust gas is directed away from the engine 10 by the exhaust manifold 12 and the exhaust down-pipe 17 and fed into the catalytic converter 19 and from there into the exhaust 20.
The catalytic converter 19 is heated by the exhaust gas and causes unburnt fuel in the exhaust gas to react with excess-air in the exhaust gas. This reaction converts HC, CO and NOx into less harmful products of combustion before releasing the exhaust gas into the atmosphere through the exhaust system 20.
For optimum efficiency of the catalytic converter 19, the EMS 16 ensures that the mixture entering the engine 10 is close to a stoichiometric air-fuel ratio. This is achieved by operating closed loop feedback control, using the oxygen sensor 18 to provide feedback of the excess-air factor X of the exhaust gas.
The efficiency of the catalytic converter 19, known as its conversion efficiency, is defined in terms of the percentage of exhaust gas converted into less harmful byproducts before they enter the exhaust system 20 and the time taken to achieve these efficiencies are normally written as T9 so that the time to reach a 10% efficiency is referred to as Tic and the time to reach a 90% efficiency is written T9c.
The conversion efficiency of the catalytic converter 19 increases as its temperature rises and is dependant on the temperature of the exhaust gas entering it for self heating. For example, a 50% conversion efficiency is reached at about 25 roc, known as the "catalyst light-off temperature", and the time taken to reach light-off is Tsc.
The catalyst light-off temperature is a critical temperature in the operating cycle of the catalytic converter 19 and is the temperature at which the catalytic converter 19 starts to produce an exothermic reaction which converts the exhaust gas reactants CO, HC, NOx into less harmful by-products of fuller combustion.
In one embodiment of this invention, the EMS 16 operates two cylinders 10a, lOb rich of a stoichiometric ratio and two cylinders lOc, lOd lean of a stoichiometric ratio.
The rich cylinders 10a, lOb do not burn all the fuel in their mixture and the surplus fuel remains in the exhaust gas as it enters the catalytic converter 19.
The lean cylinders lOc, lOd do not have enough fuel in their mixture to use all the air and the surplus air remains in the exhaust gas as it enters the catalytic converter 19.
In this manner there is a combustible mixture entering the catalytic converter 19 comprising the surplus fuel from the rich cylinders 10a, lOb and the surplus air from the lean cylinders lOc, lOd. This mixture is burnt in the catalytic converter 19 thereby raising its temperature at a greater rate than by relying on self heating from the exhaust gas produced by operating the engine 10 only at a stoichiometric ratio.
The EMS 16 operates the cylinders l0a, lOb, lOc, lod in their respective rich and lean modes as described above, between catalytic converter temperatures in the order of 200 C to 35O0C. The extra heating of the catalytic converter 19 achieved by this mode of operation significantly reduces the time taken Tsc to achieve catalyst light-off and also significantly reduces the time taken from Tic to Tso Furthermore, by employing the technique disclosed herein, it has been found that the catalyst light-off temperature is reduced to the order of 22O0C to 2300C, which helps reduce the Tso and Tic to Tgo times.
The EMS 16 uses fixed fuelling offsets of 10% of the specified cylinders, i.e. the rich cylinders 10a, lOb are operated at 110% of normal fuelling and the lean cylinders lOc, lOd are operated at 90% of normal fuelling.
The fuelling offsets may be varied in level and cylinder application and be only of fixed levels. The fuelling offsets may also be made variable and to change with engine speed, engine load and the time taken from start-up and may be operated cyclically through all the cylinders.
The engine 10 can also be operated such that k > 1, in which case the closed loop fuelling would have to be suspended or an oxygen sensor 18 used which is capable of operating away from X = 1.
This invention can also be used to re-light a catalytic converter 19 which has fallen below its light-off temperature, such as might happen after an extended period of engine 10 idling.

Claims (1)

1. An emission control system for a motor vehicle including a multi-cylinder internal combustion engine, the emission control system comprising a fuelling means arranged to control the introduction of a combustible mixture into each cylinder of the engine, an exhaust system arranged to carry an exhaust gas from the engine and a catalytic converter included in the exhaust system wherein the fuelling means is arranged to control the exhaust gas entering the catalytic converter such that the exhaust gas contains a combustible mixture for part of the engine operating cycle.
2. An emission control system according to Claim 1 wherein the part of the operating cycle commences when the catalytic converter is below a predetermined operating temperature range.
3. An emission control system according to Claim 2 wherein the combustible mixture in the exhaust gas is burnt in the catalytic converter to heat the catalytic converter up to the predetermined operating temperature range.
4. An emission control system according to Claim 3 wherein the part of the operating cycle commences after the engine has been started.
5. An emission control system according to Claim 3 or Claim 4 wherein the part of the operating cycle commences after a period during which the engine is operated at low speed for a predetermined period.
6. An emission control system according to any preceding claim wherein the fuelling means arranges the combustible mixture to be present in the exhaust gas by operating at least one cylinder rich of a stoichiometric air-fuel ratio and at least one cylinder lean of a stoichiometric air-fuel ratio.
7. An emission control system according to any preceding claim wherein the combustible mixture is present in the exhaust gas only when the catalytic converter 200cC temperature is in the order of 200 C to 350 C.
8. An emission control system according to Claim 6 or to Claim 7 wherein the combustible mixture in the exhaust gas is obtained by using a fixed fuelling offset.
9. An emission control system according to Claims 6 or to Claim 7 wherein the combustible mixture is obtained by using a variable fuelling offset.
11. An emission control system according to Claim 9 wherein the variable offset is varied cyclically through at least two cylinders.
12. An emission control system according to any preceding claim in which the system has a feedback means to provide a feedback of exhaust gas composition to the fuelling means.
20. An emission control system for a motor vehicle substantially as described herein with reference to the accompanying drawings.
GB9617548A 1996-08-21 1996-08-21 An emission control system for an engine Withdrawn GB2316338A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9617548A GB2316338A (en) 1996-08-21 1996-08-21 An emission control system for an engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9617548A GB2316338A (en) 1996-08-21 1996-08-21 An emission control system for an engine

Publications (2)

Publication Number Publication Date
GB9617548D0 GB9617548D0 (en) 1996-10-02
GB2316338A true GB2316338A (en) 1998-02-25

Family

ID=10798779

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9617548A Withdrawn GB2316338A (en) 1996-08-21 1996-08-21 An emission control system for an engine

Country Status (1)

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GB (1) GB2316338A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2793280A1 (en) * 1999-05-07 2000-11-10 Renault METHOD FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE
GB2351679A (en) * 1999-05-19 2001-01-10 Ford Global Tech Inc Air/fuel ratio control system
GB2352650A (en) * 1999-05-19 2001-02-07 Ford Global Tech Inc Emission device temperature control system
FR2798703A1 (en) * 1999-09-20 2001-03-23 Renault METHOD FOR WARMING A CATALYST EQUIPPED WITH AN INTERNAL COMBUSTION ENGINE WITH DIRECT PETROL INJECTION COMPRISING MULTIPLE CYLINDERS
WO2001050005A3 (en) * 1999-12-31 2002-03-28 Bosch Gmbh Robert Method for operating an internal combustion engine, especially of a motor vehicle
GB2379033A (en) * 2001-06-19 2003-02-26 Ford Global Tech Inc Switching the air/fuel ratio of an engine between lean and stoichiometric operating conditions
FR2838771A1 (en) * 2002-04-19 2003-10-24 Siemens Ag METHOD FOR HEATING A CATALYST IN THE EXHAUST GAS PATH OF AN INTERNAL COMBUSTION ENGINE

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4007590A (en) * 1974-06-01 1977-02-15 Nissan Motor Co., Ltd. Catalytic convertor warming up system
GB1468229A (en) * 1973-04-18 1977-03-23 Bosch Gmbh Robert Exhaust gas decontamination
US5027058A (en) * 1990-02-26 1991-06-25 Tektronix, Inc. Multi-standard video option for oscilloscope
EP0499207A1 (en) * 1991-02-12 1992-08-19 Nippondenso Co., Ltd. Control apparatus for speedily warming up catalyst in internal combustion engine
GB2256603A (en) * 1991-06-12 1992-12-16 Ford Motor Co Operation of an internal combustion engine
EP0715062A1 (en) * 1994-12-02 1996-06-05 Volkswagen Aktiengesellschaft Method for reducing pollutant of the exhaust gas of a multi-cylinder internal combustion engine
EP0718477A1 (en) * 1994-12-19 1996-06-26 Petroleum Energy Center Heating system for catalytic converter
WO1996019646A1 (en) * 1994-12-21 1996-06-27 Fev Motorentechnik Gmbh & Co. Kommanditgesellschaft Process for controlling a multiple cylinder internal combustion engine in the cold start and warming up phases

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1468229A (en) * 1973-04-18 1977-03-23 Bosch Gmbh Robert Exhaust gas decontamination
US4007590A (en) * 1974-06-01 1977-02-15 Nissan Motor Co., Ltd. Catalytic convertor warming up system
US5027058A (en) * 1990-02-26 1991-06-25 Tektronix, Inc. Multi-standard video option for oscilloscope
EP0499207A1 (en) * 1991-02-12 1992-08-19 Nippondenso Co., Ltd. Control apparatus for speedily warming up catalyst in internal combustion engine
GB2256603A (en) * 1991-06-12 1992-12-16 Ford Motor Co Operation of an internal combustion engine
EP0715062A1 (en) * 1994-12-02 1996-06-05 Volkswagen Aktiengesellschaft Method for reducing pollutant of the exhaust gas of a multi-cylinder internal combustion engine
EP0718477A1 (en) * 1994-12-19 1996-06-26 Petroleum Energy Center Heating system for catalytic converter
WO1996019646A1 (en) * 1994-12-21 1996-06-27 Fev Motorentechnik Gmbh & Co. Kommanditgesellschaft Process for controlling a multiple cylinder internal combustion engine in the cold start and warming up phases

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2793280A1 (en) * 1999-05-07 2000-11-10 Renault METHOD FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE
GB2351679B (en) * 1999-05-19 2003-04-02 Ford Global Tech Inc Air/fuel ratio control system
GB2351679A (en) * 1999-05-19 2001-01-10 Ford Global Tech Inc Air/fuel ratio control system
GB2352650A (en) * 1999-05-19 2001-02-07 Ford Global Tech Inc Emission device temperature control system
GB2352650B (en) * 1999-05-19 2003-04-02 Ford Global Tech Inc Emission device temperature control system
US6244043B1 (en) 1999-05-19 2001-06-12 Ford Global Technologies, Inc. Emission control device air/fuel ratio control system
FR2798703A1 (en) * 1999-09-20 2001-03-23 Renault METHOD FOR WARMING A CATALYST EQUIPPED WITH AN INTERNAL COMBUSTION ENGINE WITH DIRECT PETROL INJECTION COMPRISING MULTIPLE CYLINDERS
WO2001021950A1 (en) * 1999-09-20 2001-03-29 Renault Method for heating a catalyst provided in a direct fuel injection internal combustion engine comprising several cylinders
WO2001050005A3 (en) * 1999-12-31 2002-03-28 Bosch Gmbh Robert Method for operating an internal combustion engine, especially of a motor vehicle
GB2379033A (en) * 2001-06-19 2003-02-26 Ford Global Tech Inc Switching the air/fuel ratio of an engine between lean and stoichiometric operating conditions
US6604504B2 (en) 2001-06-19 2003-08-12 Ford Global Technologies, Llc Method and system for transitioning between lean and stoichiometric operation of a lean-burn engine
GB2379033B (en) * 2001-06-19 2005-04-13 Ford Global Tech Inc A method and system for transitioning between lean and stoichiometic operation of an engine
FR2838771A1 (en) * 2002-04-19 2003-10-24 Siemens Ag METHOD FOR HEATING A CATALYST IN THE EXHAUST GAS PATH OF AN INTERNAL COMBUSTION ENGINE

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Publication number Publication date
GB9617548D0 (en) 1996-10-02

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