WO2023189968A1 - Catalyst deterioration detection device, and saddle riding vehicle - Google Patents

Catalyst deterioration detection device, and saddle riding vehicle Download PDF

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Publication number
WO2023189968A1
WO2023189968A1 PCT/JP2023/011306 JP2023011306W WO2023189968A1 WO 2023189968 A1 WO2023189968 A1 WO 2023189968A1 JP 2023011306 W JP2023011306 W JP 2023011306W WO 2023189968 A1 WO2023189968 A1 WO 2023189968A1
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Prior art keywords
catalyst
air
fuel ratio
oxygen
state
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PCT/JP2023/011306
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French (fr)
Japanese (ja)
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遼亮 井畑
直樹 坂本
昌広 溝口
遼太 ▲高▼橋
祐規 坂本
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本田技研工業株式会社
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Publication of WO2023189968A1 publication Critical patent/WO2023189968A1/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
    • 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
    • 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
    • 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
    • F01N3/24—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 constructional aspects of converting 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
    • F02D41/04—Introducing corrections for particular operating conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D45/00—Electrical control not provided for in groups F02D41/00 - F02D43/00

Definitions

  • the present invention relates to a catalyst deterioration detection device and a saddle type vehicle.
  • the output voltage of the sensor is dependent on the element temperature.
  • the air-fuel ratio is in a rich state, as the exhaust gas sensor element temperature increases, It has the property that the output voltage decreases.
  • OSC it is necessary to provide a fuel amplitude (perturbation) that changes the air-fuel ratio upstream of the catalyst, but we tried to determine the timing of perturbation reversal using the output voltage of an exhaust gas sensor installed downstream of the catalyst. Then, since the reference for reversing the lean state and rich state changes depending on the sensor element temperature, an error occurs in the OSC measurement.
  • the present invention provides a catalyst that accurately detects catalyst deterioration by determining the transition timing between a lean state and a rich state based on the OSR (oxygen release amount) and OSL (oxygen storage amount) of the catalyst.
  • a deterioration detection device and a saddle-riding vehicle are provided.
  • One aspect of the present invention provides a catalyst deterioration detection device that determines a deterioration state of a catalyst based on an output signal of an oxygen sensor provided downstream of a catalyst provided in an exhaust system of the internal combustion engine.
  • perturbation means that performs a perturbation process to alternately shift the air-fuel ratio of the air-fuel mixture to a richer state or a leaner state than the stoichiometric air-fuel ratio; diagnosing means for determining whether an amplitude occurs in the output signal of the oxygen sensor and diagnosing a deterioration state of the catalyst;
  • a certain first standard is set based on the oxygen release amount OSR of the catalyst, and a second standard is a standard for transitioning from the lean state to the rich state in the perturbation process. It is characterized in that it is set based on the first output voltage value or the oxygen storage amount OSL of the catalyst.
  • the transition between the lean state and the rich state can be appropriately performed, it is possible to provide a catalyst deterioration detection device and a saddle-ride type vehicle that can detect deterioration of the catalyst from changes in OSC.
  • FIG. 1 is a diagram showing the configuration of a saddle-ride type vehicle according to an embodiment.
  • FIG. 2 is a diagram showing functional blocks of the ECU.
  • FIG. 3 is a conceptual diagram showing the relationship between OSC and emissions.
  • FIG. 4 is a diagram showing changes in air-fuel ratio due to perturbation processing.
  • FIG. 5 is a conceptual diagram showing the influence of the perturbation process on the oxygen sensor downstream of the catalyst on the output voltage change when the catalyst is functioning normally.
  • FIG. 6 is a conceptual diagram showing the influence of perturbation processing on the oxygen sensor downstream of the catalyst on the output voltage change when the catalyst has deteriorated.
  • FIG. 7 shows the measurement results of the air-fuel ratio and the output voltage of the oxygen sensor.
  • FIG. 8 is a schematic diagram illustrating a time change in the air-fuel ratio when (A) the air-fuel ratio on the upstream side of the catalyst is changed from a lean state to a rich state and then the air-fuel ratio is reversed again.
  • (B) A diagram showing the temperature dependence of the oxygen sensor output voltage.
  • (C) A diagram showing the difference in OSR when the element temperature of the oxygen sensor changes.
  • (D) A diagram showing the air-fuel ratio when perturbation processing is performed based on OSR.
  • E A diagram showing the oxygen sensor output voltage when the element temperature is 800°C.
  • FIG. 9 is a diagram showing a change over time when the air-fuel ratio on the upstream side of the catalyst (A) is changed from a rich state to a lean state.
  • B It is a figure showing a time change of an oxygen sensor output voltage.
  • C It is a schematic diagram showing the time change of the amount of oxygen stored in the OSC material of the catalyst.
  • FIG. 10 is a flowchart showing the operation of perturbation processing when determining the reversal timing from a lean state to a rich state based on the output voltage value of the oxygen sensor.
  • FIG. 11 is a flowchart of a modified embodiment showing the operation of perturbation processing when determining transition timing between a lean state and a rich state based on OSL and OSR.
  • FIG. 12 is a flowchart of processing operations for diagnosing the state of catalyst deterioration by perturbation processing.
  • FIG. 1 is a diagram showing the configuration of a saddle-ride type vehicle 100 according to an embodiment.
  • the saddle type vehicle 100 includes an internal combustion engine 5 that generates driving force, and a catalyst 10 that purifies exhaust gas discharged from the internal combustion engine 5.
  • the exhaust system 7 of the saddle type vehicle 100 is equipped with a catalyst deterioration detection device 1 that detects deterioration of the catalyst 10.
  • the saddle type vehicle 100 also includes an output device 30 that notifies the driver of deterioration of the catalyst 10.
  • the output device 30 may be a warning lamp or an image display device that visually indicates deterioration of the catalyst 10.
  • the catalyst deterioration detection device 1 detects the temperature inside the internal combustion engine based on the ECU 25 (Electronic Control Unit) that controls various devices included in the saddle type vehicle 100, and the oxygen concentration in the exhaust gas and the unburned gas concentration.
  • the exhaust gas sensor 15 includes a catalyst upstream exhaust gas sensor 15 and a catalyst downstream oxygen sensor (oxygen sensor) 20, which detect the air-fuel ratio.
  • the catalyst upstream exhaust gas sensor 15 may be, for example, a LAF (Linear Air Fuel ratio) sensor, and can detect continuous changes in the air-fuel ratio.
  • the catalyst upstream exhaust gas sensor 15 may be an oxygen sensor. In other words, a desirable combination is that the catalyst upstream exhaust gas sensor 15 is either the LAF sensor or the oxygen sensor, and the catalyst downstream exhaust gas sensor is the oxygen sensor 20.
  • the ECU 25 is a computer having a processor such as a CPU (Central Processing Unit), a ROM (Read Only Memory) in which a program is written, a RAM (Random Access Memory) for temporary storage of data, etc. .
  • various control functions are executed by the ECU 25, which is a computer, executing the program.
  • all or part of the ECU 25 may be configured by hardware each including one or more electronic circuit components.
  • FIG. 2 is a diagram showing functional blocks of the ECU 25.
  • the ECU 25 includes a storage means 47 for storing programs and data.
  • the storage means 47 may be realized by an electronic recording device, such as a RAM, a solid state drive (SSD), or a hard disc drive (HDD).
  • Various means included in the ECU 25 are realized by the programs stored in the storage means 47.
  • the ECU 25 operates the air-fuel ratio adjustment means 35 that adjusts the air-fuel ratio of the internal combustion engine 5, the perturbation means 39 that periodically changes the air-fuel ratio, and the data obtained by the perturbation means 39, thereby operating the OSC (
  • the apparatus includes a calculating means 37 for acquiring Oxygen Storage Capacity (oxygen storage capacity), etc., and a determining means 41 for determining the reversal timing between the lean state and the rich state from the result obtained by the calculating means 37.
  • the ECU 25 includes a diagnostic means 49 that diagnoses the result of the perturbation process performed by the perturbation means 39 and estimates the state of deterioration of the catalyst 10.
  • the ECU 25 also includes an input means 43 for inputting data and the like, and an output means 45 for outputting the data and the like.
  • the input means 43 may be realized by a touch panel or the like integrated with the output means 45.
  • the output means 45 may be an image display device composed of a liquid crystal panel or the like.
  • FIG. 3 is a conceptual diagram showing the relationship between OSC reduction and emissions.
  • the horizontal axis represents the OSC of the catalyst 10, and the vertical axis represents the amount of emissions containing harmful substances contained in the exhaust gas.
  • the catalyst 10 especially in the case of a three-way catalyst, contains a material (OSC material) such as cerium oxide or zirconium oxide as a co-catalyst to increase the oxygen storage capacity, and by storing and releasing oxygen, the exhaust gas is reduced. promotes purification reactions. For example, when the air-fuel ratio is rich, the OSC material releases stored oxygen to help the oxidation reaction of components contained in emissions, and when the air-fuel ratio is lean, the OSC material absorbs oxygen and reduces emissions. Helps reduce reactions of contained ingredients.
  • OSC material such as cerium oxide or zirconium oxide
  • FIG. 4 is a diagram showing changes in the air-fuel ratio due to perturbation processing by the perturbation means 39.
  • the horizontal axis represents time, and the vertical axis represents the air-fuel ratio measured by the catalyst upstream exhaust gas sensor 15 on the upstream side of the catalyst 10.
  • the perturbation means 39 changes the target air-fuel ratio from 14.0, which is a rich state, to 15.0, which is a lean state (see the solid line in FIG. 4). ).
  • FIG. 5 is a conceptual diagram showing the influence of the perturbation process on the output voltage change of the catalyst downstream oxygen sensor 20 when the catalyst 10 is functioning normally.
  • the catalyst downstream side oxygen sensor (oxygen sensor) 20 does not respond to changes in the air-fuel ratio due to the perturbation process and is approximately constant, or changes in voltage smaller than the change indicated by the oxygen sensor 20 at the ideal air-fuel ratio, for example, from 300 mV to 500 mV. It outputs a voltage change with an amplitude of approximately V 0 .
  • the OSC of the catalyst 10 decreases, so the purification rate of the catalyst 10 decreases, and the oxygen sensor 20 on the downstream side of the catalyst periodically It begins to respond (see Figure 6).
  • the OSC material of the catalyst 10 deteriorates, it will no longer be able to store enough oxygen, and the oxygen contained in the exhaust gas will flow out to the downstream side of the catalyst 10. As a result, the harmful substances in the emissions cannot be completely purified.
  • FIG. 7 shows the measurement results of the air-fuel ratio and the output voltage of the oxygen sensor 20.
  • the horizontal axis represents the air-fuel ratio measured by the exhaust gas sensor 15 on the upstream side of the catalyst, and the vertical axis represents the output voltage of the oxygen sensor 20 on the downstream side of the catalyst.
  • the plurality of measurement results correspond to the results at the element temperature (500° C. to 750° C.) of the catalyst downstream oxygen sensor 20, respectively.
  • the problem is what criteria should be used to reverse the lean state and rich state.
  • an oxygen sensor 20 is provided downstream of the catalyst 10, but the oxygen sensor 20 downstream of the catalyst has, in principle, an accuracy that can only determine whether the air-fuel ratio is rich or lean.
  • the rich state threshold voltage in FIG. 7 is when the element temperature is 750°C. While the air-fuel ratio is in state A of about 14.15, when the element temperature is 650° C., the air-fuel ratio is in state B of about 14.43. In this case, the air-fuel ratio used in the perturbation process will vary greatly depending on the situation, and it will be difficult to accurately grasp the state of deterioration of the catalyst 10.
  • FIG. 8(A) is a schematic diagram showing a time change in the air-fuel ratio when the air-fuel ratio on the upstream side of the catalyst is changed from a lean state to a rich state and then reversed again.
  • FIG. 8(B) is a diagram showing the temperature dependence of the output voltage (SVO2) of the catalyst downstream oxygen sensor 20.
  • SVO2 output voltage
  • FIG. 8C is a diagram comparing the change in OSR (OSC in a rich state) over time when the element temperature of the catalyst downstream oxygen sensor 20 is 700° C. and 800° C.
  • OSR OSR in a rich state
  • the amount of oxygen released is 200, but if the reversal is performed after the element temperature reaches 800°C, the amount of oxygen released becomes 300.
  • FIG. 8(D) is a diagram showing a temporal change in the air-fuel ratio when perturbation processing is performed based on the OSR value.
  • FIG. 8(E) is a diagram showing a temporal change in the oxygen sensor output voltage when the element temperature is 800°C.
  • FIG. 8(F) is a schematic diagram showing a change in OSR over time when a predetermined OSR is used as a threshold value for reversing the air-fuel ratio.
  • FIG. 9(A) is a diagram showing a change over time when the air-fuel ratio on the upstream side of the catalyst 10 is changed from a rich state to a lean state.
  • FIG. 9(B) shows a change in the output voltage of the catalyst downstream oxygen sensor 20 from time a in the ideal air-fuel ratio state to time b in the lean state.
  • FIG. 9C shows a temporal change in the amount of oxygen (OSL) stored in the OSC material of the catalyst 10 between time a and time b.
  • OSL amount of oxygen
  • the change in air-fuel ratio due to the element temperature of No. 20 is not large. Therefore, when performing the perturbation process to ascertain the state of deterioration of the catalyst 10, it can be said that the output voltage of the catalyst downstream oxygen sensor 20 or the OSL may be used.
  • the amount of OSR and OSL it is necessary to integrate the amount of oxygen emitted into the exhaust gas during one cycle operation of the internal combustion engine 5 and the number of cycles during the target time.
  • the calculation means 37 (see FIG. 2) performs the calculation.
  • FIG. 10 is a flowchart showing the operation of the perturbation process when determining the transition timing between the lean state and the rich state based on the output voltage value of the catalyst downstream oxygen sensor 20.
  • the air-fuel ratio adjusting means 35 adjusts the air-fuel ratio on the upstream side of the catalyst 10 (step SA1). Specifically, the air-fuel ratio adjusting means 35 adjusts the fuel injection amount and intake air amount to bring the air-fuel ratio into a rich state.
  • the calculation means 37 integrates the amount of oxygen released for each operating cycle of the internal combustion engine 5 to obtain the OSR (step SA2).
  • the OSR is integrated based on the air-fuel ratio obtained by the catalyst upstream exhaust gas sensor 15 and the number of cycles of the internal combustion engine 5.
  • the determining means 41 determines whether the OSR has reached a predetermined first integrated oxygen amount (step SA3). When the OSR becomes equal to or greater than the first integrated oxygen amount (step SA3: YES), the air-fuel ratio adjustment means 35 performs adjustment to reverse the air-fuel ratio from the rich state to the lean state (step SA4).
  • the determining means 41 acquires the output voltage value from the catalyst downstream oxygen sensor 20 (step SA5), and determines whether the output voltage value has become less than a predetermined first output voltage value (step SA6).
  • step SA6 If the output voltage value is less than the first output voltage value (step SA6: YES), the air-fuel ratio adjustment means 35 performs adjustment to reverse the air-fuel ratio from the lean state to the rich state (step SA7). Then, the process returns to step SA1. If the OSR is less than the first integrated oxygen amount (step SA3: NO), the process returns to step SA1. If the output voltage value is equal to or higher than the first output voltage value (step SA6: NO), the air-fuel ratio adjusting means 35 continues to adjust the air-fuel ratio to a leaner state, and returns to step SA5.
  • FIG. 11 shows a modified example of perturbation processing in which transition between a lean state and a rich state is performed based on OSR and OSL.
  • the air-fuel ratio adjusting means 35 adjusts the air-fuel ratio on the upstream side of the catalyst 10 (step SB1). Specifically, the air-fuel ratio adjusting means 35 adjusts the fuel injection amount and intake air amount in order to change the ideal air-fuel ratio to a lean state.
  • the calculating means 37 integrates the oxygen storage amount for each operating cycle of the internal combustion engine 5 to obtain the OSL (step SB2).
  • the OSL is integrated based on the air-fuel ratio obtained by the catalyst upstream exhaust gas sensor 15 and the number of cycles of the internal combustion engine 5.
  • the determining means 41 determines whether the OSL has reached a predetermined second integrated oxygen amount (step SB3).
  • the air-fuel ratio adjustment means 35 performs adjustment to reverse the air-fuel ratio from the lean state to the rich state (step SB4).
  • the calculation means 37 integrates the amount of oxygen released for each operating cycle of the internal combustion engine 5 to obtain the OSR (step SB5).
  • the OSR is integrated based on the air-fuel ratio obtained by the catalyst upstream exhaust gas sensor 15 and the number of cycles of the internal combustion engine 5.
  • the determining means 41 determines whether the OSR has reached a predetermined first cumulative oxygen amount (step SB6). When the OSR becomes equal to or greater than the first integrated oxygen amount (step SB6: YES), the air-fuel ratio adjustment means 35 performs adjustment to reverse the air-fuel ratio from the rich state to the lean state (step SB7). Then, the process returns to step SB1. If the OSL is less than the second integrated oxygen amount (step SB3: NO), the air-fuel ratio adjustment means 35 continues to adjust the air-fuel ratio to a leaner state (returns to step SB1). If the OSR is less than the first integrated oxygen amount (step SB6: NO), the air-fuel ratio adjustment means 35 further adjusts the air-fuel ratio to a richer state, and returns to step SB5.
  • FIG. 12 is a flowchart of a processing operation for diagnosing the state of deterioration of the catalyst 10 by the perturbation process performed by the perturbation means 39.
  • the perturbation means 39 performs perturbation processing to change the air-fuel ratio (step SC1).
  • the determining means 41 acquires the output voltage of the catalyst downstream oxygen sensor 20, and determines whether the amplitude V (see FIG. 6) occurring in the output voltage has exceeded a predetermined value (Ste SC2). If the amplitude V is greater than or equal to the predetermined value (step SC2: YES), the diagnostic means 49 determines whether the number of times the amplitude V exceeds the predetermined value is greater than or equal to the predetermined number of times (step SC3).
  • step SC3 If the number of times the amplitude V exceeds the predetermined value is greater than or equal to the predetermined number (step SC3: YES), the diagnostic means 49 diagnoses that the catalyst 10 has deteriorated (step SC4). Then, the output means 45 notifies the driver that the catalyst 10 has deteriorated (step SC5). If the amplitude V is less than the predetermined value (step SC2: NO), the perturbation means 39 performs the perturbation process again at a predetermined timing (returns to step SC1). If the number of times the amplitude V exceeds the predetermined value is less than the predetermined number (step SC3: NO), the perturbation process is performed again at a predetermined timing (return to step SC1).
  • perturbation means that performs perturbation processing to alternately shift the air-fuel ratio of air to a richer state or leaner state than the stoichiometric air-fuel ratio; diagnosing means for diagnosing a deterioration state of the catalyst by determining whether or not the output signal of the oxygen sensor occurs,
  • the reference is set based on the oxygen release amount OSR of the catalyst, and the second reference, which is a reference for transitioning from the lean state to the rich state in the perturbation process, is based on the predetermined first output of the oxygen sensor.
  • a catalyst deterioration detection device characterized in that the device is set based on a voltage value or an oxygen storage amount OSL of the catalyst. According to such a configuration, the perturbation process can be appropriately executed without providing an element temperature monitoring system to the oxygen sensor downstream of the catalyst, so that the excellent effect of accurately performing deterioration of the catalyst is achieved.
  • (Structure 2) A structure characterized in that an upstream exhaust gas sensor is provided upstream of the catalyst to detect the air-fuel ratio in the internal combustion engine from the oxygen concentration in the exhaust gas and the unburned gas concentration. 1.
  • the catalyst deterioration detection device according to 1. With such a configuration, the air-fuel ratio in the internal combustion engine can be controlled with high precision. For this reason, the perturbation process can be performed with high precision, resulting in the effect that deterioration diagnosis of the catalyst can be appropriately performed.
  • the first reference is a first integrated amount of oxygen that is an integrated value of the amount of oxygen sent to the catalyst after the air-fuel ratio measured or estimated by the upstream exhaust gas sensor becomes the ideal air-fuel ratio.
  • the catalyst deterioration detection device according to configuration 2 characterized in that: According to such a configuration, the reference for transitioning from a rich state to a lean state in perturbation processing is not influenced by the element temperature of the oxygen sensor downstream of the catalyst, so that perturbation processing can be performed with high accuracy. Therefore, it is possible to appropriately diagnose the deterioration of the catalyst.
  • the second standard is such that the air-fuel ratio measured or estimated by the upstream exhaust gas sensor is an ideal air-fuel ratio.
  • the reference for transitioning from a lean state to a rich state in perturbation processing is not influenced by the element temperature of the oxygen sensor downstream of the catalyst, so that perturbation processing can be performed with high accuracy. Therefore, it is possible to appropriately diagnose the deterioration of the catalyst.
  • a saddle-ride type vehicle comprising the catalyst deterioration detection device according to any one of Structures 1 to 4. According to such a configuration, it is possible to realize a saddle-ride type vehicle equipped with a catalyst deterioration detection device that can appropriately perform catalyst deterioration diagnosis at any timing.
  • the operation step units shown in FIGS. 10 to 12 are divided according to the main processing content in order to facilitate understanding of the operation of the catalyst deterioration detection device.
  • the invention is not limited by the name.
  • the process may be divided into more steps.
  • the process may be divided so that one step unit includes more processes.
  • the order of the steps may be changed as appropriate within a range that does not interfere with the spirit of the present invention.
  • Catalyst deterioration detection device 5 Internal combustion engine 7
  • Exhaust system 10 Catalyst 15
  • Catalyst upstream exhaust gas sensor 20 Catalyst downstream oxygen sensor (oxygen sensor) 39
  • Perturbation means 49 Diagnosis means

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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
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Abstract

Provided is a catalyst deterioration detection device that detects deterioration of a catalyst by appropriately making transitions between a lean state and a rich state, on the basis of an oxygen release amount and an oxygen storage amount of the catalyst.　A catalyst deterioration detection device of the present disclosure is characterized by comprising a perturbation means (39), and a diagnostic means (49) for diagnosing a deterioration state of a catalyst (10) by determining whether or not an output signal of an oxygen sensor (20) has an amplitude corresponding to a change in the air-fuel ratio, in accordance with a perturbation process, wherein a first reference that is a reference for making a transition from the rich state to the lean state in the perturbation process is set on the basis of an oxygen release amount OSR of the catalyst (10), and a second reference that is a reference for making a transition from the lean state to the rich state in the perturbation process is set on the basis of a predetermined first output voltage value of the oxygen sensor (20), or an oxygen storage amount OSL of the catalyst (10).

Description

触媒劣化検出装置、及び鞍乗り型車両Catalyst deterioration detection device and saddle type vehicle
　本発明は、触媒劣化検出装置、及び鞍乗り型車両に関する。 The present invention relates to a catalyst deterioration detection device and a saddle type vehicle.
　地球環境問題に対する関心の高まりとともに、内燃機関を備えた移動体について、その排気ガスが含むＮＯＸ等のエミッションについての規制が強まってきている。自動二輪車等の鞍乗り型車両についても、走行中において、排気ガスを浄化する装置である触媒の劣化を監視することが可能であるように義務づけられるようになった。言い換えれば、走行中にエミッションを直接測定せずに排気ガスを浄化する装置の劣化を検知することが必要になった。
　従来、触媒の浄化能力の劣化を、触媒のＯＳＣ（Ｏｘｉｇｅｎ　Ｓｔｏｒａｇｅ　Ｃａｐａｃｉｔｙ：酸素貯蔵能）の変化から推定する方法が知られている（例えば特開２００７－２５５３３６号公報参照）。触媒のＯＳＣと排気ガスの浄化性能には相関性があり、触媒のＯＳＣを測定することにより浄化性能の劣化を把握することができる。 BACKGROUND OF THE INVENTION As interest in global environmental issues increases, regulations regarding emissions of NOx and other substances contained in exhaust gas from mobile bodies equipped with internal combustion engines are becoming stricter. Saddle-type vehicles such as motorcycles are now required to be able to monitor the deterioration of catalysts, which are devices that purify exhaust gas, while driving. In other words, it has become necessary to detect the deterioration of the exhaust gas purifying device without directly measuring emissions while driving.
Conventionally, a method is known in which the deterioration of the purification ability of a catalyst is estimated from a change in the OSC (Oxigen Storage Capacity) of the catalyst (see, for example, Japanese Patent Application Laid-Open No. 2007-255336). There is a correlation between the OSC of the catalyst and the purification performance of exhaust gas, and by measuring the OSC of the catalyst, it is possible to understand the deterioration of the purification performance.
特開２００７－２５５３３６号公報Japanese Patent Application Publication No. 2007-255336
　しかし、触媒の下流側に設けられた排気ガスセンサがＯ２センサである場合、センサの出力電圧には素子温度依存性があり、特に空燃比がリッチ状態の場合、排気ガスセンサの素子温度の上昇とともに出力電圧が下降する性質を持つ。ＯＳＣの測定には触媒上流での空燃比を変化させる燃料振幅（パータベーション）を与える必要があるが、触媒の下流側に設けられた排気ガスセンサの出力電圧でパータベーションの反転タイミングを決定しようとすると、リーン状態とリッチ状態の反転の基準がセンサの素子温度によって変化するので、ＯＳＣの測定に誤差が生じてしまう。 However, when the exhaust gas sensor installed downstream of the catalyst is an O 2 sensor, the output voltage of the sensor is dependent on the element temperature. Especially when the air-fuel ratio is in a rich state, as the exhaust gas sensor element temperature increases, It has the property that the output voltage decreases. To measure OSC, it is necessary to provide a fuel amplitude (perturbation) that changes the air-fuel ratio upstream of the catalyst, but we tried to determine the timing of perturbation reversal using the output voltage of an exhaust gas sensor installed downstream of the catalyst. Then, since the reference for reversing the lean state and rich state changes depending on the sensor element temperature, an error occurs in the OSC measurement.
　本発明は、触媒のＯＳＲ（酸素放出量）、及びＯＳＬ（酸素貯蔵量）等に基づいて、リーン状態とリッチ状態の間の推移タイミングを決定することで、触媒の劣化を精度良く検出する触媒劣化検出装置、及び鞍乗り型車両を提供する。 The present invention provides a catalyst that accurately detects catalyst deterioration by determining the transition timing between a lean state and a rich state based on the OSR (oxygen release amount) and OSL (oxygen storage amount) of the catalyst. A deterioration detection device and a saddle-riding vehicle are provided.
　本発明の一態様は、内燃機関の排気系に設けられる触媒の下流側に設けられる酸素センサの出力信号に基づいて、前記触媒の劣化状態を判定する触媒劣化検出装置において、前記内燃機関に供給される混合気の空燃比を、理論空燃比よりリッチ状態、又はリーン状態へ交互に推移させるパータベーション処理を行うパータベーション手段と、前記パータベーション処理に応じて、前記空燃比の変化に対応した振幅が前記酸素センサの前記出力信号に生じるか否かを判定し、前記触媒の劣化状態を診断する診断手段と、を備え、前記パータベーション処理における前記リッチ状態から前記リーン状態へ推移させる基準である第１基準は、前記触媒の酸素放出量ＯＳＲに基づいて設定され、前記パータベーション処理における前記リーン状態から前記リッチ状態へ推移させる基準である第２基準は、前記酸素センサの予め定められた第１出力電圧値、又は前記触媒の酸素貯蔵量ＯＳＬに基づいて設定されることを特徴とする。
　なお、この明細書には、２０２２年３月３０日に出願された日本国特許出願・特願２０２２－０５５０３１号の全ての内容が含まれるものとする。 One aspect of the present invention provides a catalyst deterioration detection device that determines a deterioration state of a catalyst based on an output signal of an oxygen sensor provided downstream of a catalyst provided in an exhaust system of the internal combustion engine. perturbation means that performs a perturbation process to alternately shift the air-fuel ratio of the air-fuel mixture to a richer state or a leaner state than the stoichiometric air-fuel ratio; diagnosing means for determining whether an amplitude occurs in the output signal of the oxygen sensor and diagnosing a deterioration state of the catalyst; A certain first standard is set based on the oxygen release amount OSR of the catalyst, and a second standard is a standard for transitioning from the lean state to the rich state in the perturbation process. It is characterized in that it is set based on the first output voltage value or the oxygen storage amount OSL of the catalyst.
Note that this specification includes all the contents of Japanese patent application/Japanese Patent Application No. 2022-055031 filed on March 30, 2022.
　本発明の一態様によれば、リーン状態とリッチ状態の間の推移を適切におこなえるので、ＯＳＣの変化から触媒の劣化を把握できる触媒劣化検出装置、及び鞍乗り型車両を提供できる。 According to one aspect of the present invention, since the transition between the lean state and the rich state can be appropriately performed, it is possible to provide a catalyst deterioration detection device and a saddle-ride type vehicle that can detect deterioration of the catalyst from changes in OSC.
図１は、実施形態に係る鞍乗り型車両の構成を示す図である。FIG. 1 is a diagram showing the configuration of a saddle-ride type vehicle according to an embodiment. 図２は、ＥＣＵの機能ブロックを示す図である。FIG. 2 is a diagram showing functional blocks of the ECU. 図３は、ＯＳＣとエミッションの関係を示す概念図である。FIG. 3 is a conceptual diagram showing the relationship between OSC and emissions. 図４は、パータベーション処理による空燃比の変化を示す図である。FIG. 4 is a diagram showing changes in air-fuel ratio due to perturbation processing. 図５は、触媒が正常に機能している場合における触媒下流側酸素センサのパータベーション処理による出力電圧変化への影響を示す概念図である。FIG. 5 is a conceptual diagram showing the influence of the perturbation process on the oxygen sensor downstream of the catalyst on the output voltage change when the catalyst is functioning normally. 図６は、触媒が劣化している場合における触媒下流側酸素センサのパータベーション処理による出力電圧変化への影響を示す概念図である。FIG. 6 is a conceptual diagram showing the influence of perturbation processing on the oxygen sensor downstream of the catalyst on the output voltage change when the catalyst has deteriorated. 図７は、空燃比と酸素センサの出力電圧の測定結果である。FIG. 7 shows the measurement results of the air-fuel ratio and the output voltage of the oxygen sensor. 図８は、（Ａ）触媒上流側の空燃比をリーン状態からリッチ状態に変化させた後、再び空燃比を反転させた場合の空燃比の時間変化を示す模式図である。（Ｂ）酸素センサ出力電圧の温度依存性を示した図である。（Ｃ）酸素センサの素子温度が変化した場合のＯＳＲの違いを示す図である。（Ｄ）ＯＳＲを基準としてパータベーション処理を行った場合の空燃比を示す図である。（Ｅ）素子温度が８００℃の場合の酸素センサ出力電圧を示す図である。（Ｆ）閾値として所定のＯＳＲを使用して空燃比の反転をさせた場合のＯＳＲの時間変化の模式図である。FIG. 8 is a schematic diagram illustrating a time change in the air-fuel ratio when (A) the air-fuel ratio on the upstream side of the catalyst is changed from a lean state to a rich state and then the air-fuel ratio is reversed again. (B) A diagram showing the temperature dependence of the oxygen sensor output voltage. (C) A diagram showing the difference in OSR when the element temperature of the oxygen sensor changes. (D) A diagram showing the air-fuel ratio when perturbation processing is performed based on OSR. (E) A diagram showing the oxygen sensor output voltage when the element temperature is 800°C. (F) It is a schematic diagram of the time change of OSR when a predetermined OSR is used as a threshold value and the air-fuel ratio is reversed. 図９は、（Ａ）触媒上流側の空燃比をリッチ状態からリーン状態に変化させた場合の時間変化を示す図である。（Ｂ）酸素センサ出力電圧の時間変化を示す図である。（Ｃ）触媒のＯＳＣ材が貯蔵する酸素量の時間変化を示す模式図である。FIG. 9 is a diagram showing a change over time when the air-fuel ratio on the upstream side of the catalyst (A) is changed from a rich state to a lean state. (B) It is a figure showing a time change of an oxygen sensor output voltage. (C) It is a schematic diagram showing the time change of the amount of oxygen stored in the OSC material of the catalyst. 図１０は、酸素センサの出力電圧値に基づいてリーン状態からリッチ状態への反転タイミングを決定する場合のパータベーション処理の動作を示すフローチャートである。FIG. 10 is a flowchart showing the operation of perturbation processing when determining the reversal timing from a lean state to a rich state based on the output voltage value of the oxygen sensor. 図１１は、ＯＳＬとＯＳＲに基づいてリーン状態とリッチ状態の推移タイミングを決定する場合のパータベーション処理の動作を示す変形実施例のフローチャートである。FIG. 11 is a flowchart of a modified embodiment showing the operation of perturbation processing when determining transition timing between a lean state and a rich state based on OSL and OSR. 図１２は、パータベーション処理によって触媒の劣化の状態を診断する処理動作のフローチャートである。FIG. 12 is a flowchart of processing operations for diagnosing the state of catalyst deterioration by perturbation processing.
　以下、図面を参照して本発明の実施の形態について説明する。 Embodiments of the present invention will be described below with reference to the drawings.
　［実施の形態］
　図１は、実施の形態に係る鞍乗り型車両１００の構成を示す図である。鞍乗り型車両１００は、駆動力を発生させる内燃機関５と、内燃機関５から排出される排気ガスを浄化する触媒１０を備える。鞍乗り型車両１００の排気系７には、触媒１０の劣化を検出する触媒劣化検出装置１を備える。また、鞍乗り型車両１００は、触媒１０の劣化を運転者に報知する出力装置３０を備える。出力装置３０は視覚的に触媒１０の劣化を報知する警告ランプや画像表示装置でよい。触媒劣化検出装置１は、鞍乗り型車両１００が有する各種装置の制御をおこなうＥＣＵ２５（Ｅｌｅｃｔｒｏｎｉｃ　Ｃｏｎｔｒｏｌ　Ｕｎｉｔ：電子制御装置）と、排気ガスの中の酸素濃度、及び未燃ガス濃度から前記内燃機関内の前記空燃比を検出する、触媒上流側排気ガスセンサ１５と、触媒下流側酸素センサ（酸素センサ）２０を備える。触媒上流側排気ガスセンサ１５は、例えばＬＡＦ（Ｌｉｎｅａｒ　Ａｉｒ　Ｆｕｅｌ　ｒａｔｉｏ）センサであってよく、空燃比の連続的な変化を検出することができる。また、触媒上流側排気ガスセンサ１５は、酸素センサであってもよい。言い換えれば、触媒上流側排気ガスセンサ１５はＬＡＦセンサ又は酸素センサのいずれかであり、触媒下流側排気ガスセンサは酸素センサ２０である、という組合せが望ましい。 [Embodiment]
FIG. 1 is a diagram showing the configuration of a saddle-ride type vehicle 100 according to an embodiment. The saddle type vehicle 100 includes an internal combustion engine 5 that generates driving force, and a catalyst 10 that purifies exhaust gas discharged from the internal combustion engine 5. The exhaust system 7 of the saddle type vehicle 100 is equipped with a catalyst deterioration detection device 1 that detects deterioration of the catalyst 10. The saddle type vehicle 100 also includes an output device 30 that notifies the driver of deterioration of the catalyst 10. The output device 30 may be a warning lamp or an image display device that visually indicates deterioration of the catalyst 10. The catalyst deterioration detection device 1 detects the temperature inside the internal combustion engine based on the ECU 25 (Electronic Control Unit) that controls various devices included in the saddle type vehicle 100, and the oxygen concentration in the exhaust gas and the unburned gas concentration. The exhaust gas sensor 15 includes a catalyst upstream exhaust gas sensor 15 and a catalyst downstream oxygen sensor (oxygen sensor) 20, which detect the air-fuel ratio. The catalyst upstream exhaust gas sensor 15 may be, for example, a LAF (Linear Air Fuel ratio) sensor, and can detect continuous changes in the air-fuel ratio. Furthermore, the catalyst upstream exhaust gas sensor 15 may be an oxygen sensor. In other words, a desirable combination is that the catalyst upstream exhaust gas sensor 15 is either the LAF sensor or the oxygen sensor, and the catalyst downstream exhaust gas sensor is the oxygen sensor 20.
　ＥＣＵ２５は、具体的にはＣＰＵ（Ｃｅｎｔｒａｌ　ＰｒｏｃｅｓｓｉｎｇＵ　ｎｉｔ）等のプロセッサ、プログラムが書き込まれたＲＯＭ（Ｒｅａｄ　Ｏｎｌｙ　Ｍｅｍｏｒｙ）、データの一時記憶のためのＲＡＭ（Ｒａｎｄｏｍ　Ａｃｃｅｓｓ　Ｍｅｍｏｒｙ）等を有するコンピュータである。具体的には、プログラムをコンピュータであるＥＣＵ２５が実行することで各種制御機能が実行される。上記ＥＣＵ２５に代えて又はこれに加えて、上記ＥＣＵ２５の全部又は一部を、それぞれ一つ以上の電子回路部品を含むハードウェアにより構成することもできる。 Specifically, the ECU 25 is a computer having a processor such as a CPU (Central Processing Unit), a ROM (Read Only Memory) in which a program is written, a RAM (Random Access Memory) for temporary storage of data, etc. . Specifically, various control functions are executed by the ECU 25, which is a computer, executing the program. Instead of or in addition to the ECU 25, all or part of the ECU 25 may be configured by hardware each including one or more electronic circuit components.
　図２は、ＥＣＵ２５の機能ブロックを示す図である。ＥＣＵ２５はプログラムやデータを記憶する記憶手段４７を備える。具体的には記憶手段４７は、電子記録デバイス、例えば、ＲＡＭ、ＳＳＤ（Ｓｏｌｏｄ　Ｓｔａｔｅ　Ｄｒｉｖｅ）、又はＨＤＤ（Ｈａｒｄ　Ｄｉｓｃ　Ｄｒｉｖｅ）等で実現されてよい。記憶手段４７に記憶されたプログラムにより、ＥＣＵ２５が備える各種手段が実現される。ＥＣＵ２５は、内燃機関５の空燃比を調整する空燃比調整手段３５と、空燃比を周期的に変化させるパータベーション手段３９と、パータベーション手段３９によって得られたデータを演算することで、ＯＳＣ（Ｏｘｉｇｅｎ　Ｓｔｒａｇｅ　Ｃａｐａｃｉｔｙ：酸素貯蔵能）等を取得する演算手段３７と、演算手段３７で得られた結果からリーン状態とリッチ状態の反転タイミングを判定する判定手段４１を備える。ＥＣＵ２５は、パータベーション手段３９によっておこなったパータベーション処理の結果を診断して、触媒１０の劣化の状態を見積もる診断手段４９を備える。
　また、ＥＣＵ２５は、データ等を入力する入力手段４３と、データ等を出力する出力手段４５を有する。具体的には入力手段４３は出力手段４５と一体になったタッチパネル等で実現されてよい。出力手段４５は液晶パネル等で構成された画像表示装置でよい。 FIG. 2 is a diagram showing functional blocks of the ECU 25. The ECU 25 includes a storage means 47 for storing programs and data. Specifically, the storage means 47 may be realized by an electronic recording device, such as a RAM, a solid state drive (SSD), or a hard disc drive (HDD). Various means included in the ECU 25 are realized by the programs stored in the storage means 47. The ECU 25 operates the air-fuel ratio adjustment means 35 that adjusts the air-fuel ratio of the internal combustion engine 5, the perturbation means 39 that periodically changes the air-fuel ratio, and the data obtained by the perturbation means 39, thereby operating the OSC ( The apparatus includes a calculating means 37 for acquiring Oxygen Storage Capacity (oxygen storage capacity), etc., and a determining means 41 for determining the reversal timing between the lean state and the rich state from the result obtained by the calculating means 37. The ECU 25 includes a diagnostic means 49 that diagnoses the result of the perturbation process performed by the perturbation means 39 and estimates the state of deterioration of the catalyst 10.
The ECU 25 also includes an input means 43 for inputting data and the like, and an output means 45 for outputting the data and the like. Specifically, the input means 43 may be realized by a touch panel or the like integrated with the output means 45. The output means 45 may be an image display device composed of a liquid crystal panel or the like.
　図３は、ＯＳＣの減少とエミッションの関係を示す概念図である。横軸が触媒１０のＯＳＣを表し、縦軸が排気ガスに含まれる有害物質等を含むエミッションの量を表す。触媒１０、は特に三元触媒の場合においては酸素貯蔵能力の増大のために助触媒として酸化セリウムや酸化ジルコニウムといった材料（ＯＳＣ材）が含まれており、酸素を貯蔵、放出することで排気ガスの浄化反応を促進する。例えば空燃比がリッチ状態においては、ＯＳＣ材が貯蔵された酸素を放出してエミッションに含まれる成分の酸化反応を助け、空燃比がリーン状態においては、ＯＳＣ材が酸素を吸着することでエミッションに含まれる成分の還元反応を助ける。触媒１０が劣化すると、ＯＳＣが減少し、エミッションが増加する関係にある（図３参照）。そしてエミッションが所定の閾値を超えると、運転者に報知しなければならないという法規制があるため、鞍乗り型車両１００は触媒劣化検出装置１を備えることが必要である。 FIG. 3 is a conceptual diagram showing the relationship between OSC reduction and emissions. The horizontal axis represents the OSC of the catalyst 10, and the vertical axis represents the amount of emissions containing harmful substances contained in the exhaust gas. The catalyst 10, especially in the case of a three-way catalyst, contains a material (OSC material) such as cerium oxide or zirconium oxide as a co-catalyst to increase the oxygen storage capacity, and by storing and releasing oxygen, the exhaust gas is reduced. promotes purification reactions. For example, when the air-fuel ratio is rich, the OSC material releases stored oxygen to help the oxidation reaction of components contained in emissions, and when the air-fuel ratio is lean, the OSC material absorbs oxygen and reduces emissions. Helps reduce reactions of contained ingredients. When the catalyst 10 deteriorates, the OSC decreases and emissions increase (see FIG. 3). Since there is a legal regulation that requires the driver to be notified when the emissions exceed a predetermined threshold, the saddle type vehicle 100 needs to be equipped with the catalyst deterioration detection device 1.
　触媒１０の劣化の状態を検出するためには、パータベーション手段３９を用いる。具体的には、内燃機関５の吸気量や、燃料の噴射量を空燃比調整手段３５で調整することで、空燃比を周期的に変化させるパータベーション処理をおこなう。図４は、パータベーション手段３９によるパータベーション処理による空燃比の変化を示す図である。横軸は時間であり、縦軸は触媒１０の上流側において触媒上流側排気ガスセンサ１５が計測した空燃比を示す。理想空燃比を１４．７とするとき、パータベーション手段３９は、空燃比を、例えばリッチ状態である１４．０から、リーン状態である１５．０まで目標空燃比を変化させる（図４実線参照）。そしてその結果として、周期的な空燃比の変化を生じさせる（図４破線参照）。このときのパータベーション処理におけるリーン状態では、劣化した触媒１０のＯＳＣで貯蔵できない状態の酸素を含むことが望ましい。 In order to detect the state of deterioration of the catalyst 10, a perturbation means 39 is used. Specifically, the air-fuel ratio adjustment means 35 adjusts the intake air amount of the internal combustion engine 5 and the fuel injection amount, thereby performing perturbation processing that periodically changes the air-fuel ratio. FIG. 4 is a diagram showing changes in the air-fuel ratio due to perturbation processing by the perturbation means 39. The horizontal axis represents time, and the vertical axis represents the air-fuel ratio measured by the catalyst upstream exhaust gas sensor 15 on the upstream side of the catalyst 10. When the ideal air-fuel ratio is 14.7, the perturbation means 39 changes the target air-fuel ratio from 14.0, which is a rich state, to 15.0, which is a lean state (see the solid line in FIG. 4). ). As a result, periodic changes in the air-fuel ratio occur (see the broken line in FIG. 4). In the lean state in the perturbation process at this time, it is desirable that the oxygen in a state that cannot be stored in the OSC of the deteriorated catalyst 10 is included.
　図５は、触媒１０が正常に機能している場合における、触媒下流側酸素センサ２０のパータベーション処理による出力電圧変化への影響を示す概念図である。触媒１０が劣化していない状態においては、触媒１０はＯＳＣが大きく、排気ガス内に含まれる酸素を全量貯蔵し、結果として浄化性能が高くなる。そのため、触媒下流側酸素センサ（酸素センサ）２０は、パータベーション処理による空燃比の変化に応答することなく略一定か、理想空燃比で酸素センサ２０が示す変化より小さな電圧変化、例えば３００ｍＶから５００ｍＶ程度の振幅Ｖ０の電圧変化を出力する。 FIG. 5 is a conceptual diagram showing the influence of the perturbation process on the output voltage change of the catalyst downstream oxygen sensor 20 when the catalyst 10 is functioning normally. When the catalyst 10 is not deteriorated, the catalyst 10 has a large OSC and stores all the oxygen contained in the exhaust gas, resulting in high purification performance. Therefore, the catalyst downstream side oxygen sensor (oxygen sensor) 20 does not respond to changes in the air-fuel ratio due to the perturbation process and is approximately constant, or changes in voltage smaller than the change indicated by the oxygen sensor 20 at the ideal air-fuel ratio, for example, from 300 mV to 500 mV. It outputs a voltage change with an amplitude of approximately V 0 .
　これに対して、触媒１０が劣化している場合には、触媒１０のＯＳＣが低下するため触媒１０の浄化率が低下し、パータベーション処理に対して、触媒下流側酸素センサ２０が周期的な応答をするようになる（図６参照）。言い換えれば、触媒１０のＯＳＣ材が劣化すると、十分に酸素を貯蔵することができなくなり、排気ガスに含まれる酸素を触媒１０の下流側に流出させてしまうことになる。そのためエミッションの中の有害物質を浄化しきれなくなってしまう。 On the other hand, when the catalyst 10 has deteriorated, the OSC of the catalyst 10 decreases, so the purification rate of the catalyst 10 decreases, and the oxygen sensor 20 on the downstream side of the catalyst periodically It begins to respond (see Figure 6). In other words, if the OSC material of the catalyst 10 deteriorates, it will no longer be able to store enough oxygen, and the oxygen contained in the exhaust gas will flow out to the downstream side of the catalyst 10. As a result, the harmful substances in the emissions cannot be completely purified.
　図７は、空燃比と酸素センサ２０の出力電圧の測定結果を示す。横軸は触媒上流側排気ガスセンサ１５で測定された空燃比を示し、縦軸は触媒下流側酸素センサ２０の出力電圧を表す。複数ある測定結果は、それぞれ触媒下流側酸素センサ２０の素子温度（５００℃から７５０℃まで）における結果に対応する。パータベーション処理をおこなって空燃比を周期的に変化させたい場合、どのような基準を設けてリーン状態とリッチ状態を反転させるかが問題になる。本願では触媒１０の下流側に酸素センサ２０を設けているが、触媒下流側酸素センサ２０は、原則として空燃比の濃い、薄いしか判定できない精度しか持たない上に、素子温度に対して出力電圧が変わってしまうという特性がある。リッチ状態からリーン状態への反転を、触媒下流側酸素センサ２０の出力電圧に閾値を設けて行うと仮定すると、例えば図７におけるリッチ状態閾値電圧となるのは、素子温度が７５０℃であるときには空燃比が約１４．１５のＡ状態であるのに対して、素子温度が６５０℃の場合には空燃比が約１４．４３のＢ状態である。そうすると状況によって大きくパータベーション処理に用いられる空燃比が変わってしまうことになり、触媒１０の劣化の状態を正確に把握することが難しいことがわかる。 FIG. 7 shows the measurement results of the air-fuel ratio and the output voltage of the oxygen sensor 20. The horizontal axis represents the air-fuel ratio measured by the exhaust gas sensor 15 on the upstream side of the catalyst, and the vertical axis represents the output voltage of the oxygen sensor 20 on the downstream side of the catalyst. The plurality of measurement results correspond to the results at the element temperature (500° C. to 750° C.) of the catalyst downstream oxygen sensor 20, respectively. When performing perturbation processing to periodically change the air-fuel ratio, the problem is what criteria should be used to reverse the lean state and rich state. In the present application, an oxygen sensor 20 is provided downstream of the catalyst 10, but the oxygen sensor 20 downstream of the catalyst has, in principle, an accuracy that can only determine whether the air-fuel ratio is rich or lean. It has the characteristic that it changes. Assuming that the reversal from the rich state to the lean state is performed by setting a threshold value for the output voltage of the catalyst downstream oxygen sensor 20, for example, the rich state threshold voltage in FIG. 7 is when the element temperature is 750°C. While the air-fuel ratio is in state A of about 14.15, when the element temperature is 650° C., the air-fuel ratio is in state B of about 14.43. In this case, the air-fuel ratio used in the perturbation process will vary greatly depending on the situation, and it will be difficult to accurately grasp the state of deterioration of the catalyst 10.
　これに対してリーン状態からリッチ状態への反転を触媒下流側酸素センサ２０の出力電圧に閾値を設けて行うと仮定すると、図７におけるリーン状態閾値電圧となる空燃比は、触媒下流側酸素センサ２０の素子温度によらず、ほぼ一定である。したがってリーン状態からリッチ状態への反転を触媒下流側酸素センサ２０の出力電圧に閾値を設けて行うことには妥当性があることがわかる。 On the other hand, assuming that the reversal from the lean state to the rich state is performed by setting a threshold value for the output voltage of the catalyst downstream oxygen sensor 20, the air-fuel ratio that becomes the lean state threshold voltage in FIG. It is almost constant regardless of the element temperature of 20. Therefore, it can be seen that it is appropriate to perform the reversal from the lean state to the rich state by setting a threshold value for the output voltage of the catalyst downstream oxygen sensor 20.
　図８（Ａ）は、触媒上流側の空燃比をリーン状態からリッチ状態に変化させた後、再び空燃比を反転させた場合の空燃比の時間変化を示す模式図である。また図８（Ｂ）は、触媒下流側酸素センサ２０の出力電圧（ＳＶＯ２）の温度依存性を示した図である。図８（Ａ）と図８（Ｂ）からわかるように、ＳＶＯ２を基準としてリッチ状態からリーン状態へ反転させると仮定すると、触媒下流側酸素センサ２０の素子温度が７００℃である場合と８００℃である場合では、リッチ状態からリーン状態への反転のタイミングが変わってしまうことがわかる。図８（Ｃ）は、触媒下流側酸素センサ２０の素子温度が７００℃である場合と８００℃である場合について、ＯＳＲ（リッチ状態でのＯＳＣ）の時間変化を比較した図である。素子温度が７００℃でリッチ状態からリーン状態へ反転させる場合には、２００だった酸素放出量が、素子温度が８００℃になってから反転させたならば酸素放出量が３００となってしまい、触媒１０の劣化の状態を把握するためには結果のばらつきが大きすぎ、ＯＳＣを正確に見積もることが難しい。
　図８（Ｄ）は、ＯＳＲの値を基準としてパータベーション処理を行った場合の空燃比の時間変化を示す図である。例えばＯＳＲが、触媒下流側酸素センサ２０の素子温度が７００℃の場合に、所定の空燃比になったときの値になったときに、リッチ状態からリーン状態に反転させるならば、常に同量のＯＳＣが触媒１０にあるかどうかを測定することができ、触媒１０の劣化の状態を正確に把握することができる。
　図８（Ｅ）は、素子温度が８００℃の場合の酸素センサ出力電圧の時間変化を示す図である。そして、図８（Ｆ）は、空燃比を反転させる閾値として所定のＯＳＲを使用した場合のＯＳＲの時間変化を示す模式図である。リッチ状態からリーン状態への反転を、触媒下流側酸素センサ２０の出力電圧に閾値を設けて行った場合と比較すると、触媒下流側酸素センサ２０の素子温度によらず、一定の空燃比での反転処理が可能になることがわかる（図８（Ｅ）参照）。 FIG. 8(A) is a schematic diagram showing a time change in the air-fuel ratio when the air-fuel ratio on the upstream side of the catalyst is changed from a lean state to a rich state and then reversed again. Further, FIG. 8(B) is a diagram showing the temperature dependence of the output voltage (SVO2) of the catalyst downstream oxygen sensor 20. As can be seen from FIGS. 8(A) and 8(B), assuming that the rich state is reversed to the lean state based on SVO2, the element temperature of the catalyst downstream oxygen sensor 20 is 700°C and 800°C. In this case, it can be seen that the timing of reversal from the rich state to the lean state changes. FIG. 8C is a diagram comparing the change in OSR (OSC in a rich state) over time when the element temperature of the catalyst downstream oxygen sensor 20 is 700° C. and 800° C. When reversing from a rich state to a lean state when the element temperature is 700°C, the amount of oxygen released is 200, but if the reversal is performed after the element temperature reaches 800°C, the amount of oxygen released becomes 300. In order to grasp the state of deterioration of the catalyst 10, the variations in the results are too large, making it difficult to accurately estimate the OSC.
FIG. 8(D) is a diagram showing a temporal change in the air-fuel ratio when perturbation processing is performed based on the OSR value. For example, if the OSR is reversed from a rich state to a lean state when the element temperature of the oxygen sensor 20 on the downstream side of the catalyst is 700°C and the predetermined air-fuel ratio is reached, the OSR will always be the same amount. It is possible to measure whether or not the catalyst 10 has an OSC, and it is possible to accurately grasp the state of deterioration of the catalyst 10.
FIG. 8(E) is a diagram showing a temporal change in the oxygen sensor output voltage when the element temperature is 800°C. FIG. 8(F) is a schematic diagram showing a change in OSR over time when a predetermined OSR is used as a threshold value for reversing the air-fuel ratio. Compared to the case where the reversal from the rich state to the lean state is performed by setting a threshold value for the output voltage of the catalyst downstream oxygen sensor 20, it is found that the reversal from the rich state to the lean state is performed at a constant air-fuel ratio regardless of the element temperature of the catalyst downstream oxygen sensor 20. It can be seen that inversion processing becomes possible (see FIG. 8(E)).
　図９（Ａ）は、触媒１０の上流側の空燃比をリッチ状態からリーン状態に変化させた場合の時間変化を示す図である。理想空燃比の状態である時間ａからリーン状態である時間ｂの間の触媒下流側酸素センサ２０の出力電圧の変化を示すのが図９（Ｂ）である。そしてその時間ａから時間ｂの間に触媒１０のＯＳＣ材に貯蔵される酸素量（ＯＳＬ）の時間変化が図９（Ｃ）に示される。空燃比がリッチ状態からリーン状態へ変化する場合、図７で説明したようにリーン状態からリッチ状態への反転タイミングを触媒下流側酸素センサ２０の出力電圧で定めたとしても、触媒下流側酸素センサ２０の素子温度による空燃比の変化は大きくない。したがって触媒１０の劣化の状態を把握するためのパータベーション処理を行う際に、触媒下流側酸素センサ２０の出力電圧を用いても、ＯＳＬを用いてもよいと言える。
　なお、ＯＳＲやＯＳＬの量を具体的に取得するためには、内燃機関５から１サイクル運転中に、排気ガスの中に排出される酸素の量と、対象となる時間中におけるサイクル数を積算する演算を演算手段３７（図２参照）が行う。 FIG. 9(A) is a diagram showing a change over time when the air-fuel ratio on the upstream side of the catalyst 10 is changed from a rich state to a lean state. FIG. 9(B) shows a change in the output voltage of the catalyst downstream oxygen sensor 20 from time a in the ideal air-fuel ratio state to time b in the lean state. FIG. 9C shows a temporal change in the amount of oxygen (OSL) stored in the OSC material of the catalyst 10 between time a and time b. When the air-fuel ratio changes from a rich state to a lean state, even if the reversal timing from the lean state to the rich state is determined by the output voltage of the catalyst downstream oxygen sensor 20 as explained in FIG. The change in air-fuel ratio due to the element temperature of No. 20 is not large. Therefore, when performing the perturbation process to ascertain the state of deterioration of the catalyst 10, it can be said that the output voltage of the catalyst downstream oxygen sensor 20 or the OSL may be used.
In order to specifically obtain the amount of OSR and OSL, it is necessary to integrate the amount of oxygen emitted into the exhaust gas during one cycle operation of the internal combustion engine 5 and the number of cycles during the target time. The calculation means 37 (see FIG. 2) performs the calculation.
　図１０は、触媒下流側酸素センサ２０の出力電圧値に基づいてリーン状態とリッチ状態の間の推移タイミングを決定する場合のパータベーション処理の動作を示すフローチャートである。ここでは最初に空燃比を理想空燃比状態からリッチ状態へ推移させる場合を考える。まず、空燃比調整手段３５が、触媒１０の上流側の空燃比を調整する（ステップＳＡ１）。具体的には、空燃比調整手段３５が、空燃比をリッチ状態にするべく、燃料の噴射量や吸気量を調整する。演算手段３７が内燃機関５の運転サイクル毎の酸素放出量を積算してＯＳＲを取得する（ステップＳＡ２）。具体的には触媒上流側排気ガスセンサ１５で取得した空燃比と内燃機関５のサイクル数に基づいてＯＳＲを積算する。判定手段４１は、ＯＳＲが予め定められた第１積算酸素量になったかどうかを判定する（ステップＳＡ３）。ＯＳＲが第１積算酸素量以上になった場合（ステップＳＡ３：ＹＥＳ）、空燃比調整手段３５は、空燃比をリッチ状態からリーン状態へ反転推移させるべく調整をおこなう（ステップＳＡ４）。判定手段４１は、触媒下流側酸素センサ２０から出力電圧値を取得し（ステップＳＡ５）、出力電圧値が予め定められた第１出力電圧値未満になったか否かを判定する（ステップＳＡ６）。出力電圧値が第１出力電圧値未満になっていた場合（ステップＳＡ６：ＹＥＳ）、空燃比調整手段３５は、空燃比をリーン状態からリッチ状態へ反転推移すべく調整をおこなう（ステップＳＡ７）。そしてステップＳＡ１に戻る。ＯＳＲが第１積算酸素量未満だった場合（ステップＳＡ３：ＮＯ）、ステップＳＡ１に戻る。また、出力電圧値が第１出力電圧値以上だった場合（ステップＳＡ６：ＮＯ）、空燃比調整手段３５は、引き続き空燃比をさらにリーン状態へするべく調整を行い、ステップＳＡ５に戻る。 FIG. 10 is a flowchart showing the operation of the perturbation process when determining the transition timing between the lean state and the rich state based on the output voltage value of the catalyst downstream oxygen sensor 20. First, consider the case where the air-fuel ratio is transitioned from an ideal air-fuel ratio state to a rich state. First, the air-fuel ratio adjusting means 35 adjusts the air-fuel ratio on the upstream side of the catalyst 10 (step SA1). Specifically, the air-fuel ratio adjusting means 35 adjusts the fuel injection amount and intake air amount to bring the air-fuel ratio into a rich state. The calculation means 37 integrates the amount of oxygen released for each operating cycle of the internal combustion engine 5 to obtain the OSR (step SA2). Specifically, the OSR is integrated based on the air-fuel ratio obtained by the catalyst upstream exhaust gas sensor 15 and the number of cycles of the internal combustion engine 5. The determining means 41 determines whether the OSR has reached a predetermined first integrated oxygen amount (step SA3). When the OSR becomes equal to or greater than the first integrated oxygen amount (step SA3: YES), the air-fuel ratio adjustment means 35 performs adjustment to reverse the air-fuel ratio from the rich state to the lean state (step SA4). The determining means 41 acquires the output voltage value from the catalyst downstream oxygen sensor 20 (step SA5), and determines whether the output voltage value has become less than a predetermined first output voltage value (step SA6). If the output voltage value is less than the first output voltage value (step SA6: YES), the air-fuel ratio adjustment means 35 performs adjustment to reverse the air-fuel ratio from the lean state to the rich state (step SA7). Then, the process returns to step SA1. If the OSR is less than the first integrated oxygen amount (step SA3: NO), the process returns to step SA1. If the output voltage value is equal to or higher than the first output voltage value (step SA6: NO), the air-fuel ratio adjusting means 35 continues to adjust the air-fuel ratio to a leaner state, and returns to step SA5.
　図１１には、リーン状態とリッチ状態の状態間推移をＯＳＲとＯＳＬに基づいておこなう、パータベーション処理の変形実施例を示す。ここでは最初に空燃比を理想空燃比状態からリーン状態へ推移させる場合を考える。
　まず、空燃比調整手段３５が触媒１０の上流側の空燃比を調整する（ステップＳＢ１）。具体的には、空燃比調整手段３５が、理想空燃比からリーン状態にするべく、燃料の噴射量や吸気量を調整する。演算手段３７が内燃機関５の運転サイクル毎の酸素貯蔵量を積算してＯＳＬを取得する（ステップＳＢ２）。具体的には触媒上流側排気ガスセンサ１５で取得した空燃比と内燃機関５のサイクル数に基づいてＯＳＬを積算する。判定手段４１は、ＯＳＬが予め定められた第２積算酸素量になったかどうかを判定する（ステップＳＢ３）。ＯＳＬが第２積算酸素量以上になった場合（ステップＳＢ３：ＹＥＳ）、空燃比調整手段３５は、空燃比をリーン状態からリッチ状態へ反転推移させるべく調整をおこなう（ステップＳＢ４）。演算手段３７は、内燃機関５の運転サイクル毎の酸素放出量を積算してＯＳＲを取得する（ステップＳＢ５）。具体的には触媒上流側排気ガスセンサ１５で取得した空燃比と内燃機関５のサイクル数に基づいてＯＳＲを積算する。判定手段４１は、ＯＳＲが予め定められた第１積算酸素量になったかどうかを判定する（ステップＳＢ６）。ＯＳＲが第１積算酸素量以上になった場合（ステップＳＢ６：ＹＥＳ）、空燃比調整手段３５は、空燃比をリッチ状態からリーン状態へ反転推移させるべく調整をおこなう（ステップＳＢ７）。そして、ステップＳＢ１に戻る。ＯＳＬが第２積算酸素量未満だった場合（ステップＳＢ３：ＮＯ）、空燃比調整手段３５は、引き続き空燃比をさらにリーン状態へするべく調整を行う（ステップＳＢ１に戻る）。ＯＳＲが第１積算酸素量未満だった場合（ステップＳＢ６：ＮＯ）、空燃比調整手段３５は、空燃比をさらにリッチ状態に調整し、ステップＳＢ５に戻る。 FIG. 11 shows a modified example of perturbation processing in which transition between a lean state and a rich state is performed based on OSR and OSL. First, consider the case where the air-fuel ratio is transitioned from an ideal air-fuel ratio state to a lean state.
First, the air-fuel ratio adjusting means 35 adjusts the air-fuel ratio on the upstream side of the catalyst 10 (step SB1). Specifically, the air-fuel ratio adjusting means 35 adjusts the fuel injection amount and intake air amount in order to change the ideal air-fuel ratio to a lean state. The calculating means 37 integrates the oxygen storage amount for each operating cycle of the internal combustion engine 5 to obtain the OSL (step SB2). Specifically, the OSL is integrated based on the air-fuel ratio obtained by the catalyst upstream exhaust gas sensor 15 and the number of cycles of the internal combustion engine 5. The determining means 41 determines whether the OSL has reached a predetermined second integrated oxygen amount (step SB3). When the OSL becomes equal to or greater than the second integrated oxygen amount (step SB3: YES), the air-fuel ratio adjustment means 35 performs adjustment to reverse the air-fuel ratio from the lean state to the rich state (step SB4). The calculation means 37 integrates the amount of oxygen released for each operating cycle of the internal combustion engine 5 to obtain the OSR (step SB5). Specifically, the OSR is integrated based on the air-fuel ratio obtained by the catalyst upstream exhaust gas sensor 15 and the number of cycles of the internal combustion engine 5. The determining means 41 determines whether the OSR has reached a predetermined first cumulative oxygen amount (step SB6). When the OSR becomes equal to or greater than the first integrated oxygen amount (step SB6: YES), the air-fuel ratio adjustment means 35 performs adjustment to reverse the air-fuel ratio from the rich state to the lean state (step SB7). Then, the process returns to step SB1. If the OSL is less than the second integrated oxygen amount (step SB3: NO), the air-fuel ratio adjustment means 35 continues to adjust the air-fuel ratio to a leaner state (returns to step SB1). If the OSR is less than the first integrated oxygen amount (step SB6: NO), the air-fuel ratio adjustment means 35 further adjusts the air-fuel ratio to a richer state, and returns to step SB5.
　図１２は、パータベーション手段３９が行うパータベーション処理によって触媒１０の劣化の状態を診断する処理動作のフローチャートである。
　まず、パータベーション手段３９がパータベーション処理を行い、空燃比を変化させる（ステップＳＣ１）。判定手段４１は、触媒下流側酸素センサ２０の出力電圧を取得し、出力電圧に発生している振幅Ｖ（図６参照）が予め定められた所定の値以上になったか否かを判定する（ステップＳＣ２）。振幅Ｖが所定の値以上だった場合（ステップＳＣ２：ＹＥＳ）、診断手段４９は、振幅Ｖが所定の値を超えた回数が所定の回数以上になったかを判定する（ステップＳＣ３）。振幅Ｖが所定の値を超えた回数が所定の回数以上になっていた場合（ステップＳＣ３：ＹＥＳ）、診断手段４９は、触媒１０が劣化していると診断する（ステップＳＣ４）。そして、出力手段４５で運転者へ触媒１０が劣化していることを報知する（ステップＳＣ５）。振幅Ｖが所定の値未満だった場合（ステップＳＣ２：ＮＯ）、パータベーション手段３９は、予め定められたタイミングで再度パータベーション処理をおこなう（ステップＳＣ１に戻る）。振幅Ｖが所定の値を超えた回数が所定の回数未満だった場合（ステップＳＣ３：ＮＯ）、予め定められたタイミングで再度パータベーション処理をおこなう（ステップＳＣ１に戻る）。 FIG. 12 is a flowchart of a processing operation for diagnosing the state of deterioration of the catalyst 10 by the perturbation process performed by the perturbation means 39.
First, the perturbation means 39 performs perturbation processing to change the air-fuel ratio (step SC1). The determining means 41 acquires the output voltage of the catalyst downstream oxygen sensor 20, and determines whether the amplitude V (see FIG. 6) occurring in the output voltage has exceeded a predetermined value ( Step SC2). If the amplitude V is greater than or equal to the predetermined value (step SC2: YES), the diagnostic means 49 determines whether the number of times the amplitude V exceeds the predetermined value is greater than or equal to the predetermined number of times (step SC3). If the number of times the amplitude V exceeds the predetermined value is greater than or equal to the predetermined number (step SC3: YES), the diagnostic means 49 diagnoses that the catalyst 10 has deteriorated (step SC4). Then, the output means 45 notifies the driver that the catalyst 10 has deteriorated (step SC5). If the amplitude V is less than the predetermined value (step SC2: NO), the perturbation means 39 performs the perturbation process again at a predetermined timing (returns to step SC1). If the number of times the amplitude V exceeds the predetermined value is less than the predetermined number (step SC3: NO), the perturbation process is performed again at a predetermined timing (return to step SC1).
　［上記実施形態によりサポートされる構成］
　上記実施形態は、以下の構成をサポートする。 [Configurations supported by the above embodiment]
The above embodiment supports the following configurations.
　（構成１）内燃機関の排気系に設けられる触媒の下流側に設けられる酸素センサの出力信号に基づいて、前記触媒の劣化状態を判定する触媒劣化検出装置において、前記内燃機関に供給される混合気の空燃比を、理論空燃比よりリッチ状態、又はリーン状態へ交互に推移させるパータベーション処理を行うパータベーション手段と、前記パータベーション処理に応じて、前記空燃比の変化に対応した振幅が前記酸素センサの前記出力信号に生じるか否かを判定し、前記触媒の劣化状態を診断する診断手段と、を備え、前記パータベーション処理における前記リッチ状態から前記リーン状態へ推移させる基準である第１基準は、前記触媒の酸素放出量ＯＳＲに基づいて設定され、前記パータベーション処理における前記リーン状態から前記リッチ状態へ推移させる基準である第２基準は、前記酸素センサの予め定められた第１出力電圧値、又は前記触媒の酸素貯蔵量ＯＳＬに基づいて設定されることを特徴とする触媒劣化検出装置。
　このような構成によれば、触媒下流側の酸素センサに素子温度監視システムを設けずとも、パータベーション処理を適切に実行できるので触媒の劣化を精度よく行うことができるという優れた効果を奏する。 (Structure 1) In a catalyst deterioration detection device that determines a deterioration state of the catalyst based on an output signal of an oxygen sensor provided downstream of a catalyst provided in an exhaust system of the internal combustion engine, a mixture supplied to the internal combustion engine is provided. perturbation means that performs perturbation processing to alternately shift the air-fuel ratio of air to a richer state or leaner state than the stoichiometric air-fuel ratio; diagnosing means for diagnosing a deterioration state of the catalyst by determining whether or not the output signal of the oxygen sensor occurs, The reference is set based on the oxygen release amount OSR of the catalyst, and the second reference, which is a reference for transitioning from the lean state to the rich state in the perturbation process, is based on the predetermined first output of the oxygen sensor. A catalyst deterioration detection device characterized in that the device is set based on a voltage value or an oxygen storage amount OSL of the catalyst.
According to such a configuration, the perturbation process can be appropriately executed without providing an element temperature monitoring system to the oxygen sensor downstream of the catalyst, so that the excellent effect of accurately performing deterioration of the catalyst is achieved.
　（構成２）前記触媒の上流側には、排気ガスの中の酸素濃度、及び未燃ガス濃度から前記内燃機関内の前記空燃比を検出する上流側排気ガスセンサが設けられることを特徴とする構成１に記載の触媒劣化検出装置。
　このような構成によれば内燃機関における空燃比を精度よく制御できる。このためパータベーション処理を精度良く行うことができるので、触媒の劣化診断を適切に行うことができるという効果を奏する。 (Structure 2) A structure characterized in that an upstream exhaust gas sensor is provided upstream of the catalyst to detect the air-fuel ratio in the internal combustion engine from the oxygen concentration in the exhaust gas and the unburned gas concentration. 1. The catalyst deterioration detection device according to 1.
With such a configuration, the air-fuel ratio in the internal combustion engine can be controlled with high precision. For this reason, the perturbation process can be performed with high precision, resulting in the effect that deterioration diagnosis of the catalyst can be appropriately performed.
　（構成３）前記第1基準は、前記上流側排気ガスセンサによって測定される又は推定される空燃比が理想空燃比になってから前記触媒に送られる酸素量の積算値である第１積算酸素量、であることを特徴とする構成２に記載の触媒劣化検出装置。
　このような構成によれば、パータベーション処理におけるリッチ状態からリーン状態へ推移させる基準が、触媒下流側酸素センサの素子温度に影響されなくなるので、パータベーション処理を精度良く行うことができる。そのため触媒の劣化診断を適切に行うことができるという効果を奏する。 (Configuration 3) The first reference is a first integrated amount of oxygen that is an integrated value of the amount of oxygen sent to the catalyst after the air-fuel ratio measured or estimated by the upstream exhaust gas sensor becomes the ideal air-fuel ratio. The catalyst deterioration detection device according to configuration 2, characterized in that:
According to such a configuration, the reference for transitioning from a rich state to a lean state in perturbation processing is not influenced by the element temperature of the oxygen sensor downstream of the catalyst, so that perturbation processing can be performed with high accuracy. Therefore, it is possible to appropriately diagnose the deterioration of the catalyst.
　（構成４）前記第２基準が前記酸素貯蔵量ＯＳＬに基づいて設定される場合、前記第２基準は、前記上流側排気ガスセンサで測定される又は推定される空燃比が理想空燃比になってから前記触媒に送られる酸素量の積算値である第２積算酸素量である、ことを特徴とする構成２又は構成３に記載の触媒劣化検出装置。
　このような構成によれば、パータベーション処理におけるリーン状態からリッチ状態へ推移させる基準が、触媒下流側酸素センサの素子温度に影響されなくなるので、パータベーション処理を精度良く行うことができる。そのため触媒の劣化診断を適切に行うことができるという効果を奏する。 (Configuration 4) When the second standard is set based on the oxygen storage amount OSL, the second standard is such that the air-fuel ratio measured or estimated by the upstream exhaust gas sensor is an ideal air-fuel ratio. The catalyst deterioration detection device according to configuration 2 or configuration 3, wherein the second integrated amount of oxygen is an integrated value of the amount of oxygen sent to the catalyst.
According to such a configuration, the reference for transitioning from a lean state to a rich state in perturbation processing is not influenced by the element temperature of the oxygen sensor downstream of the catalyst, so that perturbation processing can be performed with high accuracy. Therefore, it is possible to appropriately diagnose the deterioration of the catalyst.
　（構成５）構成１から構成４のうちのいずれかに記載の触媒劣化検出装置を備えることを特徴とする鞍乗り型車両。
　このような構成によれば、任意のタイミングで触媒の劣化診断を適切に行うことができる触媒劣化検出装置を備える鞍乗り型車両を実現できるという効果を奏する。 (Structure 5) A saddle-ride type vehicle comprising the catalyst deterioration detection device according to any one of Structures 1 to 4.
According to such a configuration, it is possible to realize a saddle-ride type vehicle equipped with a catalyst deterioration detection device that can appropriately perform catalyst deterioration diagnosis at any timing.
　なお、上記実施の形態は本発明を適用した一態様を示すものであって、本発明は上記実施の形態に限定されるものではない。 Note that the above embodiment shows one mode to which the present invention is applied, and the present invention is not limited to the above embodiment.
　例えば、図１０から図１２に示す動作のステップ単位は、触媒劣化検出装置の動作の理解を容易にするために、主な処理内容に応じて分割したものであり、処理単位の分割の仕方や名称によって、本発明が限定されることはない。処理内容に応じて、さらに多くのステップ単位に分割してもよい。また、１つのステップ単位がさらに多くの処理を含むように分割してもよい。また、そのステップの順番は、本発明の趣旨に支障のない範囲で適宜に入れ替えてもよい。 For example, the operation step units shown in FIGS. 10 to 12 are divided according to the main processing content in order to facilitate understanding of the operation of the catalyst deterioration detection device. The invention is not limited by the name. Depending on the processing content, the process may be divided into more steps. Furthermore, the process may be divided so that one step unit includes more processes. Further, the order of the steps may be changed as appropriate within a range that does not interfere with the spirit of the present invention.
　　１　　触媒劣化検出装置
　　５　　内燃機関
　　７　　排気系
　１０　　触媒
　１５　　触媒上流側排気ガスセンサ
　２０　　触媒下流側酸素センサ（酸素センサ）
　３９　　パータベーション手段
　４９　　診断手段 1 Catalyst deterioration detection device 5 Internal combustion engine 7 Exhaust system 10 Catalyst 15 Catalyst upstream exhaust gas sensor 20 Catalyst downstream oxygen sensor (oxygen sensor)
39 Perturbation means 49 Diagnosis means

Claims (5)

  1. 　内燃機関（５）の排気系（７）に設けられる触媒（１０）の下流側に設けられる酸素センサ（２０）の出力信号に基づいて、前記触媒（１０）の劣化状態を判定する触媒劣化検出装置において、
    　前記内燃機関（５）に供給される混合気の空燃比を、理論空燃比よりリッチ状態、又はリーン状態へ交互に推移させるパータベーション処理を行うパータベーション手段（３９）と、
    　前記パータベーション処理に応じて、前記空燃比の変化に対応した振幅が前記酸素センサ（２０）の前記出力信号に生じるか否かを判定し、前記触媒（１０）の劣化状態を診断する診断手段（４９）と、
    　を備え、
    　前記パータベーション処理における前記リッチ状態から前記リーン状態へ推移させる基準である第１基準は、前記触媒（１０）の酸素放出量ＯＳＲに基づいて設定され、
    　前記パータベーション処理における前記リーン状態から前記リッチ状態へ推移させる基準である第２基準は、前記酸素センサ（１０）の予め定められた第１出力電圧値、又は前記触媒の酸素貯蔵量ＯＳＬに基づいて設定される
    　ことを特徴とする触媒劣化検出装置。     Catalyst deterioration detection that determines the deterioration state of the catalyst (10) based on the output signal of an oxygen sensor (20) provided downstream of the catalyst (10) in the exhaust system (7) of the internal combustion engine (5). In the device,
    perturbation means (39) that performs perturbation processing to alternately shift the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine (5) to a richer state or a leaner state from the stoichiometric air-fuel ratio;
    Diagnosis means for determining whether or not an amplitude corresponding to a change in the air-fuel ratio occurs in the output signal of the oxygen sensor (20) in accordance with the perturbation process, and diagnosing a deterioration state of the catalyst (10). (49) and
    Equipped with
    A first criterion, which is a criterion for transitioning from the rich state to the lean state in the perturbation process, is set based on the oxygen release amount OSR of the catalyst (10),
    The second criterion, which is a criterion for transitioning from the lean state to the rich state in the perturbation process, is based on a predetermined first output voltage value of the oxygen sensor (10) or the oxygen storage amount OSL of the catalyst. A catalyst deterioration detection device characterized by being set.
  2. 　前記触媒（１０）の上流側には、排気ガスの中の酸素濃度、及び未燃ガス濃度から前記内燃機関（５）内の前記空燃比を検出する触媒上流側排気ガスセンサ（１５）が設けられることを特徴とする請求項１に記載の触媒劣化検出装置。 A catalyst upstream exhaust gas sensor (15) is provided upstream of the catalyst (10) to detect the air-fuel ratio in the internal combustion engine (5) from the oxygen concentration in the exhaust gas and the unburned gas concentration. The catalyst deterioration detection device according to claim 1, characterized in that:
  3. 　前記第１基準は、前記触媒上流側排気ガスセンサ（１５）によって測定される又は推定される空燃比が理想空燃比になってから前記触媒（１０）に送られる酸素量の積算値である第１積算酸素量、であることを特徴とする請求項２に記載の触媒劣化検出装置。 The first reference is an integrated value of the amount of oxygen sent to the catalyst (10) after the air-fuel ratio measured or estimated by the catalyst upstream exhaust gas sensor (15) becomes the ideal air-fuel ratio. 3. The catalyst deterioration detection device according to claim 2, wherein the cumulative amount of oxygen is the cumulative amount of oxygen.
  4. 　前記第２基準が前記酸素貯蔵量ＯＳＬに基づいて設定される場合、前記第２基準は、前記触媒上流側排気ガスセンサ（１５）で測定される又は推定される空燃比が理想空燃比になってから前記触媒（１０）に送られる酸素量の積算値である第２積算酸素量である、ことを特徴とする請求項２又は請求項３に記載の触媒劣化検出装置。 When the second standard is set based on the oxygen storage amount OSL, the second standard is such that the air-fuel ratio measured or estimated by the catalyst upstream exhaust gas sensor (15) is an ideal air-fuel ratio. The catalyst deterioration detecting device according to claim 2 or 3, wherein the second integrated amount of oxygen is an integrated value of the amount of oxygen sent from the catalyst to the catalyst (10).
  5. 　請求項１から請求項４のうちのいずれか一項に記載の触媒劣化検出装置（１）を備えることを特徴とする鞍乗り型車両。
          A saddle-ride type vehicle comprising the catalyst deterioration detection device (1) according to any one of claims 1 to 4.
PCT/JP2023/011306 2022-03-30 2023-03-22 Catalyst deterioration detection device, and saddle riding vehicle WO2023189968A1 (en)

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Publication number Priority date Publication date Assignee Title
JP2005180201A (en) * 2003-12-16 2005-07-07 Toyota Motor Corp Catalyst degradation diagnosis device for internal combustion engine
JP2007255336A (en) * 2006-03-24 2007-10-04 Honda Motor Co Ltd Catalyst degradation-detecting device
JP2018123794A (en) * 2017-02-02 2018-08-09 本田技研工業株式会社 Catalyst deterioration determination device
JP2022007483A (en) * 2020-06-26 2022-01-13 トヨタ自動車株式会社 Diagnosis device for deterioration of exhaust emission control catalyst

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005180201A (en) * 2003-12-16 2005-07-07 Toyota Motor Corp Catalyst degradation diagnosis device for internal combustion engine
JP2007255336A (en) * 2006-03-24 2007-10-04 Honda Motor Co Ltd Catalyst degradation-detecting device
JP2018123794A (en) * 2017-02-02 2018-08-09 本田技研工業株式会社 Catalyst deterioration determination device
JP2022007483A (en) * 2020-06-26 2022-01-13 トヨタ自動車株式会社 Diagnosis device for deterioration of exhaust emission control catalyst

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