WO2013180364A1 - Apparatus and method of diagnosing fault of oxidation catalyst - Google Patents

Apparatus and method of diagnosing fault of oxidation catalyst Download PDF

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Publication number
WO2013180364A1
WO2013180364A1 PCT/KR2012/010759 KR2012010759W WO2013180364A1 WO 2013180364 A1 WO2013180364 A1 WO 2013180364A1 KR 2012010759 W KR2012010759 W KR 2012010759W WO 2013180364 A1 WO2013180364 A1 WO 2013180364A1
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WIPO (PCT)
Prior art keywords
continuous time
oxidation catalyst
sensor
fault
outputting
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PCT/KR2012/010759
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French (fr)
Inventor
Cheol Woong Park
Chang Ki Kim
Sun Youp Lee
Seung Mook Oh
Tae Young Kim
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Korea Institute Of Machinery & Materials
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Publication of WO2013180364A1 publication Critical patent/WO2013180364A1/en

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    • 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
    • F01N3/103—Oxidation catalysts for HC and CO only
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F01N2560/025—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting O2, e.g. lambda sensors
    • 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
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/04—Methods of control or diagnosing
    • F01N2900/0416—Methods of control or diagnosing using the state of a sensor, e.g. of an exhaust gas sensor
    • 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
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
    • F01N2900/1402—Exhaust gas composition
    • 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
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
    • F01N2900/1621—Catalyst conversion efficiency
    • 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
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
    • F01N2900/1624—Catalyst oxygen storage capacity
    • 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
    • Y02T10/40—Engine management systems

Definitions

  • the present invention relates to an apparatus and a method of diagnosing a fault of an oxidation catalyst for rapidly diagnosing degradation state of an oxidation catalyst and providing fault information to a driver.
  • a method of examining a vehicle driven on a general road is performed under a predetermined condition of idling or other fixed-speed driving.
  • the examination of the vehicle has a high regulation limit, so that an exhaust gas acceptable limit applied to a manufacturing company has a problem in substantially achieving the effect.
  • a vehicle manufacturing company makes a vehicle turn on a fault indication light when the amount of exhaust gas discharged from a vehicle is equal to or larger than the regulation limit by a predetermined range, which is called On Board diagnostics. Accordingly, whether the exhaust gas discharged from the vehicle meets or fails the regulation limit may be identified through turning-on or turning-off of the fault indication light.
  • the present invention has been made in an effort to provide an apparatus and a method of diagnosing a fault of an oxidation catalyst having advantages of rapidly taking measures against a fault by identifying a degradation state of an oxidation catalyst installed in an exhaust gas line in real time.
  • An exemplary embodiment of the present invention provides a method of diagnosing a fault of an oxidation catalyst in a state where the oxidation catalyst is installed in an exhaust line through which exhaust gas passes and an sensor is installed at a rear end of the oxidation catalyst, the method including: (a) measuring a first continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a normal state of the oxidation catalyst; (b) measuring a second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a driving state of a vehicle; (c) outputting a comparison value by comparing the first continuous time and the second continuous time; and (d) when the comparison value exceeds a predetermined range in step (c), providing a driver with a warning signal.
  • the first continuous time may be an continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in an initial mounting state of the sensor.
  • the measurement of the second continuous time in step (b) may include: (b-1) temporarily stopping fuel spray by decelerating the vehicle; (b-2) accelerating the vehicle after step (b-1) and enriching mixed gas flowing in the engine; and (b-3) measuring a time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor after step (b-2).
  • step (d) when it is represented that the second continuous time is shorter than the first continuous time by 30% or less, a fault signal may be provided to the driver.
  • Another exemplary embodiment of the present invention provides an apparatus for diagnosing a fault of an oxidation catalyst, including: an sensor installed at a rear end of the oxidation catalyst installed in an exhaust gas line of a vehicle; and a controller configured to output a comparison value by comparing a first continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a normal state of the oxidation catalyst and a second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a driving state of the vehicle, and identify whether the comparison value exceeds a predetermined range.
  • the display unit may be a fault indication light installed inside the vehicle.
  • the senor is installed at the rear end of the oxidation catalyst installed in the exhaust gas line and a degradation state of the oxidation catalyst is identified in real time by measuring an output time of the air/fuel ratio voltage output from the sensor, thereby reducing a time for taking measures against a fault when degradation of the oxidation catalyst is generated.
  • FIG. 1 is a drawing schematically illustrating an apparatus for diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention.
  • FIG. 2 is a drawing schematically illustrating an output state of a voltage signal corresponding to an air/fuel ratio in a normal state of an oxidation catalyst.
  • FIG. 3 is a drawing schematically illustrating an output state of of a voltage signal corresponding to an air/fuel ratio in an abnormal state of an oxidation catalyst.
  • FIG. 4 is a flowchart schematically illustrating a method of diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention.
  • FIG. 1 is a drawing schematically illustrating an apparatus for diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention.
  • an apparatus 100 for diagnosing a fault of an oxidation catalyst includes an sensor 10 installed at a rear end of an oxidation catalyst 13 in an exhaust gas line 11 of a vehicle, a controller 20 for identifying a fault of the oxidation catalyst 13 by identifying a sensing signal of the oxidation sensor 10, and a display unit 30 for notifying a driver of a fault when the fault of the oxidation catalyst 13 is generated.
  • the oxidation catalyst 13 is installed in the exhaust gas line 11 of the vehicle to serve to oxidize and reduce unburned hydrocarbon, carbon monoxide, and the like generated in a vehicle engine 15. That is, when fuel is incompletely combusted during the combustion of the fuel, unburned hydrocarbon, carbon monoxide, nitrogen oxide, and the like are generated. The materials, such as unburned hydrocarbon, carbon monoxide, and nitrogen oxide, considerably exert negative influences on an environment. Accordingly, when combustion gas combusted from the exhaust gas of the vehicle passes through the oxidation catalyst 13, it is possible to prevent environmental pollution by removing unburned hydrocarbon and carbon monoxide generated during the incomplete combustion of the fuel.
  • the sensor 10 senses whether an oxidation-reduction reaction is normally performed in the oxidation catalyst 13 by measuring a state of the exhaust gas passing through the oxidation catalyst 13.
  • the sensor 10 is installed at a rear side of a position at which the oxidation catalyst 13 is installed in the exhaust gas line 11.
  • the sensor 10 can output a voltage signal corresponding to air/fuel ratio by using the exhaust gas passing through the oxidation catalyst 13.
  • the sensor 10 determines a degradation state of the oxidation catalyst 13 by identifying a variation state of the voltage signal corresponding to air/fuel ratio.
  • a first continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in a normal state at an initial stage of the mounting of the oxidation catalyst 13 is measured by using the sensor 10.
  • the normal state of the oxidation catalyst 13 means a state in which the normal oxidation catalyst 13 of which degradation is not generated is installed right after the release of the vehicle.
  • a second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio at the rear end of the oxidation catalyst 13 is measured by using the sensor 10 in a continuous driving state of the vehicle. Then, signals measured at the first continuous time and the second continuous time sensed by the sensor 10 are transmitted to the controller 20.
  • the first continuous time may maintain a predetermined value in the normal state of the oxidation catalyst 13.
  • the controller 20 may be applied as an engine control unit (ECU) of the vehicle in the exemplary embodiment of the present invention.
  • the controller 20 compares the first continuous time and the second continuous time transmitted from the sensor 10, and when it is determined that the second continuous time exceeds a range of the first continuous time, the controller 20 generates a fault signal.
  • the controller 20 may generate the fault signal.
  • FIG. 2 is a drawing schematically illustrating an output state of a voltage signal corresponding to an air/fuel ratio in a normal state of an oxidation catalyst
  • FIG. 3 is a drawing schematically illustrating an output state of a voltage signal corresponding to an air/fuel ratio in an abnormal state of an oxidation catalyst.
  • the oxidation-reduction reaction is normally performed in the normal state of the oxidation catalyst 13, so that a voltage signal corresponding to a stoichiometric air/fuel ratio is output for the first continuous time A.
  • the controller 20 when the controller 20 identifies that the second continuous time B is shorter than the first continuous time A, the controller 20 diagnoses a state of the oxidation catalyst 13 as a degradation state and transmits a fault signal to the display unit 30.
  • the first continuous time A is determined according to a specification of the oxidation catalyst 13 and may be changed to a random value.
  • the display unit 30 refers to a fault indication light installed inside the vehicle, and is operated by receiving a signal from the controller 20 and notifies a driver of a fault state of the oxidation catalyst 13.
  • FIG. 4 is a flowchart schematically illustrating a method of diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention.
  • the same reference numeral as that of FIG. 1 refers to the same element having the same function. Hereinafter, a detailed description of the same reference numeral will be omitted.
  • the oxidation catalyst 13 is installed in the exhaust gas line 11 through which exhaust gas passes, and the sensor 10 is installed at the rear end of the oxidation catalyst 13. Then, the first continuous time A outputted from the sensor 10 in a normal operation state of the initial stage of the mounting of the oxidation catalyst 13 is transmitted to the controller 20 (S10).
  • the first continuous time A refers to a continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor, and is determined according to a specification of the oxidation catalyst 13, and may be changed to a random value.
  • the second continuous time B of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor 10 in a driving state of the vehicle is measured (S20), and transmitted to the controller 20.
  • the controller 20 outputs a comparison value of the first continuous time A with the second continuous time B (S30).
  • the second continuous time B is changed according to a degradation state of the oxidation catalyst 13.
  • the comparison value of the first continuous time A with the second continuous time B in step S30 is induced from the controller 20, and the degradation state of the oxidation catalyst 13 is determined based on the comparison value.
  • step S21 the vehicle is accelerated to supply fuel to the engine, so that mixed gas flowing in the engine is momentarily enriched (S22).
  • step S22 the second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor 10 is measured (S23). More particularly, when hydrocarbon or carbon monoxide is discharged from the engine according to the performance of step S22, the discharged hydrocarbon or carbon monoxide is reacted with oxygen adsorbed to the oxidation catalyst 13, so that the sensor 10 outputs the voltage signal corresponding to a stoichiometric air/fuel ratio for a predetermined time.
  • the voltage signal corresponding to an air/fuel ratio is changed according to a time for which hydrocarbon or carbon monoxide generated in step S22 is oxidized and reduced from the oxidation catalyst 13.
  • the output time of the voltage signal corresponding to a stoichiometric air/fuel ratio outputted from the sensor 10 is decreased.
  • the output time of the voltage signal corresponding to an stoichiometric air/fuel ratio outputted from the sensor 10 is relatively increased.
  • Step S50 is performed by the controller 20 configurable with the ECU, and when the second continuous time B is shorter than the first continuous time A, the controller 20 may provide the fault signal to the driver. That is, in the exemplary embodiment of the present invention, when the second continuous time B is shorter than the first continuous time A by 30% or less, the fault signal may be generated. In the provision of the fault signal, information on an abnormal state of the oxidation catalyst 13 may be provided to the driver by turning on a fault indication light installed inside the vehicle.

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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)
  • Materials Engineering (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

Disclosed is a method of diagnosing a fault of an oxidation catalyst The method of diagnosing a fault of an oxidation catalyst includes: (a) measuring a first continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in a sensor in a normal state of the oxidation catalyst; (b) measuring a second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a driving state of a vehicle; (c) outputting a comparison value by comparing the first continuous time and the second continuous time; and (d) when the comparison value exceeds a predetermined range in step (c), providing a driver with a warning signal.

Description

APPARATUS AND METHOD OF DIAGNOSING FAULT OF OXIDATION CATALYST
The present invention relates to an apparatus and a method of diagnosing a fault of an oxidation catalyst for rapidly diagnosing degradation state of an oxidation catalyst and providing fault information to a driver.
A method of examining a vehicle driven on a general road is performed under a predetermined condition of idling or other fixed-speed driving. The examination of the vehicle has a high regulation limit, so that an exhaust gas acceptable limit applied to a manufacturing company has a problem in substantially achieving the effect.
Accordingly, a vehicle manufacturing company makes a vehicle turn on a fault indication light when the amount of exhaust gas discharged from a vehicle is equal to or larger than the regulation limit by a predetermined range, which is called On Board diagnostics. Accordingly, whether the exhaust gas discharged from the vehicle meets or fails the regulation limit may be identified through turning-on or turning-off of the fault indication light.
However, since it is difficult to diagnose a degradation state of an oxidation catalyst installed in an exhaust gas line in order to adjust the amount of exhaust gas, it frequently fails to rapidly take measures against a fault of the vehicle even though the exhaust gas of the oxidation catalyst is excessively discharged.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
The present invention has been made in an effort to provide an apparatus and a method of diagnosing a fault of an oxidation catalyst having advantages of rapidly taking measures against a fault by identifying a degradation state of an oxidation catalyst installed in an exhaust gas line in real time.
An exemplary embodiment of the present invention provides a method of diagnosing a fault of an oxidation catalyst in a state where the oxidation catalyst is installed in an exhaust line through which exhaust gas passes and an sensor is installed at a rear end of the oxidation catalyst, the method including: (a) measuring a first continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a normal state of the oxidation catalyst; (b) measuring a second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a driving state of a vehicle; (c) outputting a comparison value by comparing the first continuous time and the second continuous time; and (d) when the comparison value exceeds a predetermined range in step (c), providing a driver with a warning signal.
The first continuous time may be an continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in an initial mounting state of the sensor.
The measurement of the second continuous time in step (b) may include: (b-1) temporarily stopping fuel spray by decelerating the vehicle; (b-2) accelerating the vehicle after step (b-1) and enriching mixed gas flowing in the engine; and (b-3) measuring a time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor after step (b-2).
In step (d), when it is represented that the second continuous time is shorter than the first continuous time by 30% or less, a fault signal may be provided to the driver.
Another exemplary embodiment of the present invention provides an apparatus for diagnosing a fault of an oxidation catalyst, including: an sensor installed at a rear end of the oxidation catalyst installed in an exhaust gas line of a vehicle; and a controller configured to output a comparison value by comparing a first continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a normal state of the oxidation catalyst and a second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a driving state of the vehicle, and identify whether the comparison value exceeds a predetermined range.
The display unit may be a fault indication light installed inside the vehicle.
According to the exemplary embodiment of the present invention, the sensor is installed at the rear end of the oxidation catalyst installed in the exhaust gas line and a degradation state of the oxidation catalyst is identified in real time by measuring an output time of the air/fuel ratio voltage output from the sensor, thereby reducing a time for taking measures against a fault when degradation of the oxidation catalyst is generated.
FIG. 1 is a drawing schematically illustrating an apparatus for diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention.
FIG. 2 is a drawing schematically illustrating an output state of a voltage signal corresponding to an air/fuel ratio in a normal state of an oxidation catalyst.
FIG. 3 is a drawing schematically illustrating an output state of of a voltage signal corresponding to an air/fuel ratio in an abnormal state of an oxidation catalyst.
FIG. 4 is a flowchart schematically illustrating a method of diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention.
Hereinafter, an apparatus and a method of diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited by exemplary embodiments disclosed below, but may be variously implemented into different forms, and these embodiments are provided only for illustrative purposes and for full understanding of the scope of the present invention by those skilled in the art.
FIG. 1 is a drawing schematically illustrating an apparatus for diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention.
As illustrated in FIG. 1, an apparatus 100 for diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention includes an sensor 10 installed at a rear end of an oxidation catalyst 13 in an exhaust gas line 11 of a vehicle, a controller 20 for identifying a fault of the oxidation catalyst 13 by identifying a sensing signal of the oxidation sensor 10, and a display unit 30 for notifying a driver of a fault when the fault of the oxidation catalyst 13 is generated.
The oxidation catalyst 13 is installed in the exhaust gas line 11 of the vehicle to serve to oxidize and reduce unburned hydrocarbon, carbon monoxide, and the like generated in a vehicle engine 15. That is, when fuel is incompletely combusted during the combustion of the fuel, unburned hydrocarbon, carbon monoxide, nitrogen oxide, and the like are generated. The materials, such as unburned hydrocarbon, carbon monoxide, and nitrogen oxide, considerably exert negative influences on an environment. Accordingly, when combustion gas combusted from the exhaust gas of the vehicle passes through the oxidation catalyst 13, it is possible to prevent environmental pollution by removing unburned hydrocarbon and carbon monoxide generated during the incomplete combustion of the fuel.
The sensor 10 senses whether an oxidation-reduction reaction is normally performed in the oxidation catalyst 13 by measuring a state of the exhaust gas passing through the oxidation catalyst 13.
The sensor 10 is installed at a rear side of a position at which the oxidation catalyst 13 is installed in the exhaust gas line 11. The sensor 10 can output a voltage signal corresponding to air/fuel ratio by using the exhaust gas passing through the oxidation catalyst 13. The sensor 10 determines a degradation state of the oxidation catalyst 13 by identifying a variation state of the voltage signal corresponding to air/fuel ratio.
More particularly, a first continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in a normal state at an initial stage of the mounting of the oxidation catalyst 13 is measured by using the sensor 10. Here, the normal state of the oxidation catalyst 13 means a state in which the normal oxidation catalyst 13 of which degradation is not generated is installed right after the release of the vehicle.
Further, as illustrated in FIG. 3, a second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio at the rear end of the oxidation catalyst 13 is measured by using the sensor 10 in a continuous driving state of the vehicle. Then, signals measured at the first continuous time and the second continuous time sensed by the sensor 10 are transmitted to the controller 20. Here, the first continuous time may maintain a predetermined value in the normal state of the oxidation catalyst 13.
The controller 20 may be applied as an engine control unit (ECU) of the vehicle in the exemplary embodiment of the present invention. The controller 20 compares the first continuous time and the second continuous time transmitted from the sensor 10, and when it is determined that the second continuous time exceeds a range of the first continuous time, the controller 20 generates a fault signal. In the exemplary embodiment of the present invention, when the second continuous time is shorter than the first continuous time by 30% or less, the controller 20 may generate the fault signal.
FIG. 2 is a drawing schematically illustrating an output state of a voltage signal corresponding to an air/fuel ratio in a normal state of an oxidation catalyst, and FIG. 3 is a drawing schematically illustrating an output state of a voltage signal corresponding to an air/fuel ratio in an abnormal state of an oxidation catalyst.
As illustrated in FIG. 2, the oxidation-reduction reaction is normally performed in the normal state of the oxidation catalyst 13, so that a voltage signal corresponding to a stoichiometric air/fuel ratio is output for the first continuous time A.
However, as illustrated in FIG. 3, when the oxidation catalyst 13 is degraded during the continuous driving of the vehicle, oxygen adsorption performance deteriorates, so that an oxygen concentration is decreased and thus the second continuous time B of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio according to the oxidation-reduction reaction decreased.
Accordingly, when the controller 20 identifies that the second continuous time B is shorter than the first continuous time A, the controller 20 diagnoses a state of the oxidation catalyst 13 as a degradation state and transmits a fault signal to the display unit 30. Here, the first continuous time A is determined according to a specification of the oxidation catalyst 13 and may be changed to a random value.
The display unit 30 refers to a fault indication light installed inside the vehicle, and is operated by receiving a signal from the controller 20 and notifies a driver of a fault state of the oxidation catalyst 13.
Through the aforementioned configuration, it is possible to rapidly identify a fault state of the oxidation catalyst 13 and decrease a time required for taking measures against the fault.
FIG. 4 is a flowchart schematically illustrating a method of diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention. The same reference numeral as that of FIG. 1 refers to the same element having the same function. Hereinafter, a detailed description of the same reference numeral will be omitted.
Hereinafter, a method of diagnosing a fault of an oxidation catalyst according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 4.
First, the oxidation catalyst 13 is installed in the exhaust gas line 11 through which exhaust gas passes, and the sensor 10 is installed at the rear end of the oxidation catalyst 13. Then, the first continuous time A outputted from the sensor 10 in a normal operation state of the initial stage of the mounting of the oxidation catalyst 13 is transmitted to the controller 20 (S10). Here, the first continuous time A refers to a continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor, and is determined according to a specification of the oxidation catalyst 13, and may be changed to a random value.
Next, the second continuous time B of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor 10 in a driving state of the vehicle, is measured (S20), and transmitted to the controller 20. The controller 20 outputs a comparison value of the first continuous time A with the second continuous time B (S30). The second continuous time B is changed according to a degradation state of the oxidation catalyst 13. The comparison value of the first continuous time A with the second continuous time B in step S30 is induced from the controller 20, and the degradation state of the oxidation catalyst 13 is determined based on the comparison value.
In the meantime, a method of measuring the second continuous time by using the sensor 10 in step S20 will be described in detail below.
First, a speed of the vehicle is reduced and fuel spray is temporarily stopped (S21). Accordingly, a concentration of oxygen flowing in the engine is increased.
After step S21, the vehicle is accelerated to supply fuel to the engine, so that mixed gas flowing in the engine is momentarily enriched (S22).
Next, after step S22, the second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor 10 is measured (S23). More particularly, when hydrocarbon or carbon monoxide is discharged from the engine according to the performance of step S22, the discharged hydrocarbon or carbon monoxide is reacted with oxygen adsorbed to the oxidation catalyst 13, so that the sensor 10 outputs the voltage signal corresponding to a stoichiometric air/fuel ratio for a predetermined time. Here, the voltage signal corresponding to an air/fuel ratio is changed according to a time for which hydrocarbon or carbon monoxide generated in step S22 is oxidized and reduced from the oxidation catalyst 13.
Accordingly, when the oxidation catalyst 13 is in a degraded state, the output time of the voltage signal corresponding to a stoichiometric air/fuel ratio outputted from the sensor 10 is decreased. When the oxidation catalyst 13 is in the normal state, the output time of the voltage signal corresponding to an stoichiometric air/fuel ratio outputted from the sensor 10 is relatively increased.
Next, when the comparison value in step S30 exceeds a predetermined range (S40), a fault signal is provided to a driver (S50). Step S50 is performed by the controller 20 configurable with the ECU, and when the second continuous time B is shorter than the first continuous time A, the controller 20 may provide the fault signal to the driver. That is, in the exemplary embodiment of the present invention, when the second continuous time B is shorter than the first continuous time A by 30% or less, the fault signal may be generated. In the provision of the fault signal, information on an abnormal state of the oxidation catalyst 13 may be provided to the driver by turning on a fault indication light installed inside the vehicle.
As described above, it is possible to rapidly identify a degradation state of the oxidation catalyst 13 through measurement of the continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor 10 installed at the rear end of the oxidation catalyst 13 and reduce a time for taking measures against a fault.
The present invention has been described with reference to the exemplary embodiments illustrated in the drawings. However, the present invention is not limited thereto, and various modified examples or other embodiments belonging to the scope equivalent to that of the present invention are available by those skilled in the art. Accordingly, the sole protection scope of the present invention will be defined by the accompanying claims
<Description of symbols>
10...sensor 11...Exhaust gas line
13...Oxidation catalyst 15...Vehicle engine
20...Controller 30...Display unit

Claims (7)

  1. A method of diagnosing a fault of an oxidation catalyst in a state where the oxidation catalyst is installed in an exhaust line through which exhaust gas passes and an sensor is installed at a rear end of the oxidation catalyst, the method comprising:
    (a) measuring a first continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a normal state of the oxidation catalyst;
    (b) measuring a second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a driving state of a vehicle;
    (c) outputting a comparison value by comparing the first continuous time and the second continuous time; and
    (d) when the comparison value exceeds a predetermined range in step (c), providing a driver with a warning signal.
  2. The method of claim 1, wherein:
    the first continuous time is a continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in an initial mounting state of the sensor.
  3. The method of claim 2, wherein:
    the measurement of the second continuous time in step (b) comprises:
    (b-1) temporarily stopping fuel spray by decelerating the vehicle;
    (b-2) accelerating the vehicle after step (b-1) and enriching mixed gas flowing in the engine; and
    (b-3) measuring a time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor after step (b-2).
  4. The method of claim 3, wherein:
    in step (d), when it is represented that the second continuous time is shorter than the first continuous time by 30% or less, a fault signal is provided to the driver.
  5. An apparatus for diagnosing a fault of an oxidation catalyst, comprising:
    an sensor installed at a rear end of the oxidation catalyst installed in an exhaust gas line of a vehicle;
    a controller configured to output a comparison value by comparing a first continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a normal state of the oxidation catalyst and a second continuous time of outputting a voltage signal corresponding to a stoichiometric air/fuel ratio in the sensor in a driving state of the vehicle, and identify whether the comparison value exceeds a predetermined range; and
    a display unit configured to provide a driver with a fault signal when the comparison value of the controller exceeds the predetermined range.
  6. The apparatus of claim 5, wherein:
    the display unit is a fault indication light installed inside the vehicle.
  7. The apparatus of claim 5, wherein:
    when it is represented that the second continuous time is shorter than the first continuous time by 30% or less, a fault signal is provided to the driver.
PCT/KR2012/010759 2012-05-31 2012-12-11 Apparatus and method of diagnosing fault of oxidation catalyst WO2013180364A1 (en)

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JPH08200128A (en) * 1995-01-31 1996-08-06 Nippondenso Co Ltd Air-fuel ratio controller for internal combustion engine
JP2004278457A (en) * 2003-03-18 2004-10-07 Nissan Motor Co Ltd Catalyst deterioration diagnosing device of internal combustion engine
JP2004308455A (en) * 2003-04-02 2004-11-04 Nissan Motor Co Ltd Diagnostic device of exhaust gas post-treatment device for internal combustion engine
US20060201138A1 (en) * 2005-03-10 2006-09-14 Mc Lain Kurt D Catalyst condition monitor based on differential area under the oxygen sensors curve algorithm
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