WO1999035388A1 - Monitoring of leaks in an exhaust treatment system of an internal combustion engine - Google Patents

Monitoring of leaks in an exhaust treatment system of an internal combustion engine Download PDF

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Publication number
WO1999035388A1
WO1999035388A1 PCT/IB1999/000009 IB9900009W WO9935388A1 WO 1999035388 A1 WO1999035388 A1 WO 1999035388A1 IB 9900009 W IB9900009 W IB 9900009W WO 9935388 A1 WO9935388 A1 WO 9935388A1
Authority
WO
WIPO (PCT)
Prior art keywords
catalytic converter
air
engine
temperature
treatment system
Prior art date
Application number
PCT/IB1999/000009
Other languages
French (fr)
Inventor
Guido Dickers
Klemens Grieser
Johann Himmelsbach
Patrick Phlips
Original Assignee
Ford Global Technologies, Inc.
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 Ford Global Technologies, Inc. filed Critical Ford Global Technologies, Inc.
Publication of WO1999035388A1 publication Critical patent/WO1999035388A1/en

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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
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F01N11/007—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
    • 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
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F01N11/002—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
    • 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
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1439—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the position of the sensor
    • F02D41/1441—Plural sensors
    • 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
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1446—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being exhaust temperatures
    • 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
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/02—Catalytic activity of catalytic converters
    • 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
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F02D2041/224—Diagnosis of the fuel system
    • F02D2041/225—Leakage detection
    • 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
    • F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
    • F02D41/187—Circuit arrangements for generating control signals by measuring intake air flow using a hot wire flow sensor
    • 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
    • Y02T10/40—Engine management systems

Definitions

  • the invention relates to leak monitoring for an internal combustion engine having an exhaust treatment system including a catalytic converter, and in particular such an engine provided with an electronic engine control unit with a device for fixing the air/fuel ratio lambda to be supplied to the engine as a function of various engine operating parameters, wherein the range of adjustment for lambda also includes values greater than 1.0, a device for setting the air/fuel ratio predetermined by the engine control unit and a device for approximate determination of the temperature of the exhaust gas treatment system.
  • a nitrogen oxide trap may be provided in the exhaust treatment system, to decrease the nitrogen oxide emissions occurring during fuel-economising lean mixture operation of the engine.
  • a known problem both with three-way converters and with nitrogen oxide traps is that particular, predetermined limiting temperatures of the active substances must not be exceeded if damage or accelerated ageing is to be avoided.
  • the object of the present invention is to provide a method by which damage to or accelerated ageing of the catalytic converter in the event of leaks can be avoided.
  • the invention provides a method of monitoring leaks in an exhaust treatment system, including a catalytic converter, of an internal combustion engine wherein the air/fuel ratio lambda at the catalytic converter is measured and wherein at least one temperature of the catalytic converter is determined, in which, in the event of a maximum value related to the temperature of the converter being exceeded, the normal control of the air/fuel ratio is stopped and a stoichiometric or slightly lean mixture is set.
  • the air/fuel mixture is exclusively adjusted to have lambda approximately equal to or greater than 1.0.
  • Exceeding the temperature limit is preferably monitored using two temperatures at the converter (inlet temperature TE and outlet temperature TA, or the difference between them) .
  • the predetermined temperature difference may preferably be selected so as to be about 50 to 150°C.
  • the temperatures required for the detection of a leak may be obtained from the internal resistance of sensors for the determination of the air/fuel ratio
  • the unburned fuel reaches the catalytic converter, and after-burning occurs there. Since this combustion is very limited in respect both of time and place, it can lead to local overheating of the active substances in the catalytic converter (so-called hot spots) .
  • the setting of the mixture in the event of an excessive temperature difference at the catalytic converter is preferably done by determination of the mass air flow and setting the throttle valve.
  • the preferred setting of the mass fuel flow is done by setting of the through-flow quantity at the injection valve.
  • the duration of the injection pulse may be varied.
  • the multi-cylinder internal combustion engine 10 is controlled by an electronic engine control unit 12 which receives a plurality of input signals 24, e.g. the current engine speed or the current position of the driver's accelerator pedal.
  • the engine control unit executes algorithms for control of an electronic throttle valve 20, an ignition system 18 and an injection system 26.
  • the engine exhaust gases are supplied to an exhaust gas treatment system 28. This can, for example, comprise a three-way catalytic converter 14 and a nitrogen oxide trap 16. The temperature of the exhaust gas at the catalytic converter 14 is measured by a temperature sensor 22.
  • a sensor 23 is provided.

Landscapes

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

Abstract

In a method of monitoring leaks in an exhaust treatment system of an internal combustion engine (10) having a three-way catalytic converter (14) with or without a nitrogen oxide trap (16) and an electronic engine control unit (12) with a device for fixing the air/fuel ratio lambda to be supplied to the engine as a function of various engine operating parameters, in the event of temperatures determined at the catalytic converter exceeding specific limiting values, stoichiometric operation is set and lambda control is interrupted.

Description

MONITORING OF LEAKS IN AN EXHAUST TREATMENT SYSTEM OF AN INTERNAL COMBUSTION ENGINE
The invention relates to leak monitoring for an internal combustion engine having an exhaust treatment system including a catalytic converter, and in particular such an engine provided with an electronic engine control unit with a device for fixing the air/fuel ratio lambda to be supplied to the engine as a function of various engine operating parameters, wherein the range of adjustment for lambda also includes values greater than 1.0, a device for setting the air/fuel ratio predetermined by the engine control unit and a device for approximate determination of the temperature of the exhaust gas treatment system.
In addition to a conventional three-way catalytic converter a nitrogen oxide trap (NOx-trap) may be provided in the exhaust treatment system, to decrease the nitrogen oxide emissions occurring during fuel-economising lean mixture operation of the engine.
A known problem both with three-way converters and with nitrogen oxide traps is that particular, predetermined limiting temperatures of the active substances must not be exceeded if damage or accelerated ageing is to be avoided.
Nowadays it is often usual to locate the catalytic converter relatively close to the engine in order to bring about rapid heating up of the converter after a cold start of the engine. With this arrangement the catalytic converter - above all in the case of prolonged operation of the engine in the full load region - can reach temperatures which lie in the region of the safety limit.
It is known to employ measures (e.g. artificial enrichment of the mixture) to lower the exhaust gas temperature if the temperature threatens to exceed the safety limit. Hitherto, however, in controlling the internal combustion engine attention has not been paid to the fact that the catalytic converter can be adversely affected if a leak occurs between the engine and the three-way converter whereby an increased amount of oxygen gets into the catalytic converter which, together with unburned hydrocarbons or carbon monoxide, can lead to overheating of the catalytic converter and hence to the safety temperature limit being exceeded. This can be the case particularly with an enriched mixture (lambda less than 1) .
The object of the present invention is to provide a method by which damage to or accelerated ageing of the catalytic converter in the event of leaks can be avoided.
To achieve this object, the invention provides a method of monitoring leaks in an exhaust treatment system, including a catalytic converter, of an internal combustion engine wherein the air/fuel ratio lambda at the catalytic converter is measured and wherein at least one temperature of the catalytic converter is determined, in which, in the event of a maximum value related to the temperature of the converter being exceeded, the normal control of the air/fuel ratio is stopped and a stoichiometric or slightly lean mixture is set.
Thus in accordance with the invention, when the temperature of the catalytic converter exceeds a predetermined limiting temperature, the air/fuel mixture is exclusively adjusted to have lambda approximately equal to or greater than 1.0.
Thus in accordance with the invention, if a leak occurs and the predetermined temperature limit is exceeded, operation of the engine with a higher proportion of fuel than corresponds to a stoichiometric air/fuel ratio (lambda = 1.0 standardised to the stoichiometric value) is prevented.
During the adjustment to a stoichiometric or slightly lean mixture the lambda control which would otherwise take place is turned off, thereby preventing values from the lambda sensor which have been falsified by the leak being used for the control .
Exceeding the temperature limit is preferably monitored using two temperatures at the converter (inlet temperature TE and outlet temperature TA, or the difference between them) .
The predetermined temperature difference may preferably be selected so as to be about 50 to 150°C.
The temperatures required for the detection of a leak may be obtained from the internal resistance of sensors for the determination of the air/fuel ratio
Particularly in full load operation, in which a rich mixture is set in order to meet the demand for torque, the supply of false air through a leak can quickly lead to increase in the temperature of the catalytic converter. In this situation the crude exhaust gas also contains unburned fuel.
The unburned fuel reaches the catalytic converter, and after-burning occurs there. Since this combustion is very limited in respect both of time and place, it can lead to local overheating of the active substances in the catalytic converter (so-called hot spots) .
As indicated above, in accordance with the invention, this is avoided by the turning off of the lambda control in combination with adjustment to a value for lambda which is greater than or equal to unity.
The setting of the mixture in the event of an excessive temperature difference at the catalytic converter is preferably done by determination of the mass air flow and setting the throttle valve.
The preferred setting of the mass fuel flow is done by setting of the through-flow quantity at the injection valve. Alternatively, the duration of the injection pulse may be varied.
The invention will now be described in more detail, by way of example, with reference to the accompanying drawing.
The multi-cylinder internal combustion engine 10 is controlled by an electronic engine control unit 12 which receives a plurality of input signals 24, e.g. the current engine speed or the current position of the driver's accelerator pedal. The engine control unit executes algorithms for control of an electronic throttle valve 20, an ignition system 18 and an injection system 26. By means of the electronic throttle valve 20 and the injection system 18 the air/fuel ratio lambda of the mixture to be supplied to the cylinders can be varied within wide limits: in particular under certain operating conditions a lean air/fuel ratio (e.g. lambda = 1.6) can be set, or the supply of fuel can be completely shut off (coasting operation) . The engine exhaust gases are supplied to an exhaust gas treatment system 28. This can, for example, comprise a three-way catalytic converter 14 and a nitrogen oxide trap 16. The temperature of the exhaust gas at the catalytic converter 14 is measured by a temperature sensor 22.
To determine the mass air flow a sensor 23 is provided.

Claims

1. Method of monitoring leaks in an exhaust treatment system, including a catalytic converter, of an internal combustion engine wherein the air/fuel ratio lambda at the catalytic converter is measured and wherein at least one temperature of the catalytic converter is determined, characterised in that in the event of a maximum value related to the temperature of the converter being exceeded the normal control of the air/fuel ratio is stopped and a stoichiometric or slightly lean mixture is set.
2. Leak monitoring method according to claim 1, characterised in that the setting of the mixture is effected using the mass air flow.
3. Leak monitoring method according to claim 2, characterised in that the through-flow quantity at the injection nozzle is varied.
4. Leak monitoring method according to any preceding claim, characterised in that the duration of the fuel injection is varied.
5. Leak monitoring method according to any preceding claim, characterised in that a difference between inlet and outlet temperatures is used as the maximum value related to the temperature of the catalytic converter.
6. Leak monitoring method according to any preceding claim, characterised in that the temperatures required for the detection of a leak are obtained from the internal resistance of sensors for the determination of the air/fuel ratio .
PCT/IB1999/000009 1998-01-09 1999-01-06 Monitoring of leaks in an exhaust treatment system of an internal combustion engine WO1999035388A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP98100276.9 1998-01-09
EP98100276A EP0937875B1 (en) 1998-01-09 1998-01-09 Monitoring of leakage in an exhaust gas treatment device of a combustion engine

Publications (1)

Publication Number Publication Date
WO1999035388A1 true WO1999035388A1 (en) 1999-07-15

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Application Number Title Priority Date Filing Date
PCT/IB1999/000009 WO1999035388A1 (en) 1998-01-09 1999-01-06 Monitoring of leaks in an exhaust treatment system of an internal combustion engine

Country Status (3)

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EP (1) EP0937875B1 (en)
DE (1) DE59800035D1 (en)
WO (1) WO1999035388A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6568246B1 (en) * 2002-01-11 2003-05-27 Ford Global Technologies, L.L.C. System and method for detecting an air leak in an exhaust system coupled to an engine
WO2012118429A1 (en) * 2011-03-02 2012-09-07 Scania Cv Ab Method for fault detection in an exhaust system
WO2012118430A1 (en) * 2011-03-02 2012-09-07 Scania Cv Ab Method for fault detection in an exhaust system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5848743A (en) * 1981-09-07 1983-03-22 Toyota Motor Corp Apparatus for preventing deterioration of catalyst used in internal-combustion engine
US5158063A (en) * 1990-12-28 1992-10-27 Honda Giken Kogyo K.K. Air-fuel ratio control method for internal combustion engines
US5351526A (en) * 1992-06-13 1994-10-04 Aft Atlas Fahrzeugtechnik Gmbh Apparatus for monitoring leakage into exhaust lines
US5372036A (en) * 1993-11-22 1994-12-13 Ford Motor Company Exhaust leak detection
EP0719931A1 (en) * 1994-12-26 1996-07-03 Hitachi, Ltd. Exhaust control device of internal combustion engine

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5848743A (en) * 1981-09-07 1983-03-22 Toyota Motor Corp Apparatus for preventing deterioration of catalyst used in internal-combustion engine
US5158063A (en) * 1990-12-28 1992-10-27 Honda Giken Kogyo K.K. Air-fuel ratio control method for internal combustion engines
US5351526A (en) * 1992-06-13 1994-10-04 Aft Atlas Fahrzeugtechnik Gmbh Apparatus for monitoring leakage into exhaust lines
US5372036A (en) * 1993-11-22 1994-12-13 Ford Motor Company Exhaust leak detection
EP0719931A1 (en) * 1994-12-26 1996-07-03 Hitachi, Ltd. Exhaust control device of internal combustion engine

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 007, no. 133 (M - 221) 10 June 1983 (1983-06-10) *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6568246B1 (en) * 2002-01-11 2003-05-27 Ford Global Technologies, L.L.C. System and method for detecting an air leak in an exhaust system coupled to an engine
WO2012118429A1 (en) * 2011-03-02 2012-09-07 Scania Cv Ab Method for fault detection in an exhaust system
WO2012118430A1 (en) * 2011-03-02 2012-09-07 Scania Cv Ab Method for fault detection in an exhaust system

Also Published As

Publication number Publication date
EP0937875A1 (en) 1999-08-25
DE59800035D1 (en) 1999-11-04
EP0937875B1 (en) 1999-09-29

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