WO2021176671A1 - Catalyst deterioration diagnostic device - Google Patents

Catalyst deterioration diagnostic device Download PDF

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Publication number
WO2021176671A1
WO2021176671A1 PCT/JP2020/009530 JP2020009530W WO2021176671A1 WO 2021176671 A1 WO2021176671 A1 WO 2021176671A1 JP 2020009530 W JP2020009530 W JP 2020009530W WO 2021176671 A1 WO2021176671 A1 WO 2021176671A1
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Prior art keywords
catalyst
air
fuel ratio
oxygen concentration
concentration sensor
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PCT/JP2020/009530
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French (fr)
Japanese (ja)
Inventor
晋二 藤田
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本田技研工業株式会社
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Application filed by 本田技研工業株式会社 filed Critical 本田技研工業株式会社
Priority to CN202080097947.2A priority Critical patent/CN115244283B/en
Priority to BR112022017146A priority patent/BR112022017146A2/en
Priority to JP2022504899A priority patent/JP7372440B2/en
Priority to PCT/JP2020/009530 priority patent/WO2021176671A1/en
Publication of WO2021176671A1 publication Critical patent/WO2021176671A1/en

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10Exhaust 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
    • F01N3/18Exhaust 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
    • F01N3/20Exhaust 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
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/40Engine management systems

Definitions

  • the present invention relates to a catalyst deterioration diagnostic device, and more particularly to a catalyst deterioration diagnostic device that detects the degree of deterioration of the catalyst device provided in the exhaust pipe of an engine.
  • Patent Document 1 oxygen concentration sensors are arranged on the upstream side and the downstream side of the catalyst device, respectively, and the catalyst device is based on the change in the output signal of the oxygen concentration sensor when the air-fuel ratio is switched between the rich side and the lean side.
  • the configuration for detecting the degree of deterioration of the above is disclosed.
  • Patent Document 1 In the configuration of Patent Document 1, two oxygen concentration sensors are required and it is costly, so a configuration in which the degree of deterioration of the catalyst is executed by one oxygen concentration sensor has been sought.
  • An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a catalyst deterioration diagnostic device capable of detecting the degree of deterioration of the catalyst device with one oxygen concentration sensor.
  • the present invention comprises an oxygen concentration sensor (90) provided on the downstream side of the catalyst (C) provided in the exhaust pipe (19) of the engine (E) and the oxygen concentration sensor (90).
  • a catalyst deterioration diagnosis device having a control unit (100) for diagnosing the degree of deterioration of the catalyst (C) based on the output signal of the above, the air-fuel ratio of the air-fuel mixture supplied to the engine (E) is calculated from the stoichiometric air-fuel ratio.
  • the control unit (100) is provided with a catalyst means (105) for performing a catalyst process that alternately shifts toward the target air-fuel ratio set on the rich side and the lean side, and the control unit (100) is said to be in the middle of the pattern processing.
  • the first feature is that the air-fuel ratio on the upstream side of the catalyst (C) is estimated and detected based on the target air-fuel ratio and the output signal of the oxygen concentration sensor (90).
  • the AFR as the air-fuel ratio on the upstream side of the catalyst (C) has a theoretical air-fuel ratio of 14.5, and is a coefficient indicating the degree of transition to the rich side or the lean side in the perturbation treatment for detecting the degree of deterioration.
  • Is K, and the correction coefficient determined by the target air-fuel ratio and the output signal of the oxygen concentration sensor (90) is H.
  • the third feature is that the correction coefficient is calculated by performing PID control on the deviation between the target air-fuel ratio and the output signal of the oxygen concentration sensor (90).
  • control unit (100) has a fifth feature in that it calculates the oxygen adsorption capacity of the catalyst (C) by integrating the amount of inflow oxygen and diagnoses the deteriorated state of the catalyst (C). ..
  • the air-fuel ratio of the air-fuel mixture supplied to the engine (E) is set to be richer and leaner than the stoichiometric air-fuel ratio.
  • the control unit (100) is provided with a catalyst means (105) that performs a catalyst processing that alternately shifts toward a target air-fuel ratio set on the side, and the control unit (100) is capable of performing the target air-fuel ratio and the target air-fuel ratio during the catalyst processing. Since the air-fuel ratio on the upstream side of the catalyst (C) is estimated and detected based on the output signal of the oxygen concentration sensor (90), the degree of deterioration of the catalyst is determined by only one oxygen concentration sensor provided on the downstream side of the catalyst. Can be detected.
  • the AFR as the air-fuel ratio on the upstream side of the catalyst (C) has a theoretical air-fuel ratio of 14.5, and the perturbation treatment for detecting the degree of deterioration has a rich side or a lean side.
  • the coefficient indicating the degree of transition is K
  • the correction coefficient determined by the target air-fuel ratio and the output signal of the oxygen concentration sensor (90) is H
  • the following calculation formula AFR 14.5 ⁇ K ⁇ Since it is obtained by H, it is possible to calculate the air-fuel ratio on the upstream side of the catalyst by a simple calculation formula.
  • the correction coefficient is calculated by performing PID control on the deviation between the target air-fuel ratio and the output signal of the oxygen concentration sensor (90), and thus is a general feedback process. It is possible to calculate the correction coefficient using.
  • control unit (100) calculates the oxygen adsorption capacity of the catalyst (C) by integrating the amount of inflow oxygen, and diagnoses the deteriorated state of the catalyst (C). It is possible to detect the degree of deterioration of the catalyst with only one oxygen concentration sensor provided on the downstream side of the catalyst.
  • FIG. 1 is a left side view of a motorcycle 1 as a saddle-type vehicle according to an embodiment of the present invention.
  • a head pipe 12 that rotatably supports the steering stem 10 is attached to the front end of the vehicle body frame 2 of the motorcycle 1 which is a saddle-mounted vehicle.
  • a steering handle 6 is attached to the upper end of the steering stem 10 via a top bridge (not shown).
  • the top bridge that rotates integrally with the steering stem 10 supports a pair of left and right front forks 16 together with a bottom bridge (not shown) that is fixed to the steering stem 10 at the lower part of the head pipe 12.
  • a front wheel WF provided with a brake disc 35 is rotatably supported at the lower end of the front fork 16.
  • a generator cover Ea and a drive sprocket cover Eb are attached to the left side of the engine E in the vehicle width direction.
  • a radiator 15 for engine cooling water is arranged in front of the hanger frame 17.
  • the vehicle body frame 2 supports the engine E at the upper and rear parts of the engine E, and the swing arm 24 is swingably supported by the pivot 21.
  • a pair of left and right foot-resting steps 23 for the driver are provided below the pivot plate 21a that pivotally supports the pivot 21, and a foldable passenger step 21b is provided on the step bracket 21c on the rear upper side thereof.
  • a main stand 22 that floats the rear wheel WR of the motorcycle 1 to stand on its own when the vehicle is stopped, and a side stand 140 that tilts the vehicle body to the left to stand on its own are attached.
  • the main stand 22 and the side stand 140 are retracted by swinging about 90 degrees toward the rear side of the vehicle body.
  • An exhaust device 20 that purifies and silences the exhaust gas of the engine E and discharges it to the rear is attached to the lower part of the vehicle body of the motorcycle 1.
  • the exhaust device 20 has an exhaust pipe 19 connected to an exhaust port of a cylinder to guide exhaust gas to the rear, and a muffler 26 connected to the rear end of the exhaust pipe 19.
  • An exhaust pipe cover 5a that covers the front and sides of the exhaust pipe 19 is arranged below the front of the cylinder head 18.
  • the swing arm 24 pivotally supported by the pivot 21 is suspended from the vehicle body frame 2 by a rear cushion (not shown).
  • the driving force of the engine E is transmitted to the rear wheel WR, which is rotatably supported by the rear end of the swing arm 24, via the drive chain 25.
  • a storage box 4 accessed from the large opening / closing lid 3 is provided at a position covered by the side cowl 5, which is an exterior part.
  • a headlight 13 is arranged in front of the side cowl 5, and a pair of left and right flasher lamps 11 and a windscreen 9 are arranged above the headlight 13.
  • a knuckle guard 8 and a rearview mirror 7 are attached to the left and right steering handles 6, respectively.
  • a pair of left and right fog lamps 14 are attached to the lower part of the side cowl 15 at a position outside the front fork 16 in the vehicle width direction, and above the front wheel WF, a front that prevents mud splashing on the vehicle body and the like.
  • a fender 36 is attached.
  • a rear frame 29 that supports the fuel tank 28 and the like is attached to the rear of the vehicle body frame 2.
  • the left and right sides of the rear frame 29 are covered with seat cowls 31, and a driver's seat 27 and a passenger's seat 30 are arranged above the seat cowl 31.
  • a taillight device 32 is attached to the rear end of the seat cowl 31, and a rear flasher lamp 33 is supported by a rear fender 34 extending rearward and downward from the seat cowl 31.
  • FIG. 2 is a cross-sectional view of the enlarged diameter portion 61 provided in the middle of the exhaust pipe 19.
  • the catalyst device C is housed in the enlarged diameter portion 61, and the air-fuel ratio sensor 80 is arranged behind the catalyst device C.
  • the enlarged diameter portion 61 holds the catalyst device C inside the front outer cylinder 76 via the packing 75, and the rear end portion of the catalyst device C and the front outer cylinder 76 is formed on the outer periphery of the funnel-shaped rear outer cylinder 78. It is configured by welding and fixing with a welding bead B to the surface.
  • the air-fuel ratio sensor 90 is held by being screwed into a pedestal 86 as a mounting boss welded and fixed to the rear outer cylinder 78.
  • the air-fuel ratio sensor 90 may be a LAF sensor that can linearly detect changes in oxygen concentration, or an O2 sensor that can only detect that the air-fuel ratio is at the theoretical air-fuel ratio by reversing the output value at the boundary of the theoretical air-fuel ratio. can. Further, the oxygen concentration sensor 90 can be a sensor with a heater whose temperature is optimally controlled by a heater controlled by the control unit 100.
  • FIG. 3 is a schematic diagram showing the relationship between the engine E and the oxygen concentration sensor 90.
  • the exhaust device 20 has an oxygen concentration sensor 90 located on the downstream side of the catalyst device C.
  • An injector 57 which is a fuel injection device, is provided in the intake pipe 56 of the engine E, and an intake air amount sensor 55 is arranged upstream of the injector 57.
  • the sensor signal of the intake air amount sensor 55 is input to the air amount detection unit 58.
  • the injector control unit 59 controls the injector 57 so that combustion is performed at an appropriate air-fuel ratio based on signals from the air amount detection unit 58 and the control unit 100 in addition to information on throttle operation and engine speed.
  • the deterioration diagnosis of the catalyst device C is performed by two sensors, an oxygen concentration sensor provided on the upstream side of the catalyst device C and an oxygen concentration sensor provided on the downstream side of the catalyst device C.
  • attention is paid to the relationship between the sensor output of the upstream oxygen concentration sensor and the sensor output of the downstream oxygen concentration sensor, and the change due to the deterioration of the catalyst device C is detected.
  • the oxygen concentration in the exhaust gas changes due to the feedback control.
  • the deterioration state of the catalyst is determined by determining whether or not the change cycle of the output of the downstream oxygen concentration sensor corresponds to the predetermined catalyst deterioration conditions. Can be determined. Specifically, a counting method can be used in which the number of times the downstream oxygen concentration sensor makes a predetermined fluctuation within a predetermined time is counted.
  • Such deterioration diagnosis processing is executed with a patrol processing in which the air-fuel ratio of the internal combustion engine is alternately changed to the rich side and the lean side. Specifically, whether or not the amount of oxygen accumulated using the upstream oxygen concentration sensor exceeds the threshold value until the value of the downstream oxygen concentration sensor reaches a predetermined value by switching the air fuel ratio to the lean side. Then, the air-fuel ratio is switched to the rich side, and the amount of oxygen accumulated using the upstream oxygen concentration sensor exceeds the threshold value until the value of the downstream oxygen concentration sensor reaches a predetermined value. Deterioration of the catalyst device C is detected by repeating the operation of observing whether or not.
  • a lean operation is executed so as to supply an amount of oxygen that can be accumulated in the normal catalyst device C but cannot be accumulated in the deteriorated catalyst device C, and then the lean operation is executed. Switch to the rich operation and execute the rich operation so as to release almost all the accumulated oxygen. Then, if the catalyst device C is not deteriorated, the output of the oxygen concentration sensor 90 hardly changes, but if it is deteriorated, the output of the oxygen concentration sensor 90 changes significantly, so that the deterioration diagnosis becomes possible. ..
  • the oxygen concentration sensor is not provided on the upstream side of the catalyst device C
  • the oxygen concentration on the upstream side of the catalyst device C is estimated and detected based on the output of the downstream oxygen concentration sensor, and the estimated detected value is used. It is characterized in that deterioration diagnosis of the catalyst device C is performed based on the above.
  • FIG. 4 is a block diagram showing a configuration of a control unit 100 that diagnoses deterioration of the catalyst device C.
  • the control unit 100 includes a perturbation means 105, a catalyst pre-catalyst air-fuel ratio calculation unit 101, a pre-catalyst oxygen amount calculation unit, a pre-catalyst oxygen amount integration unit 103, and a catalyst diagnosis unit 104.
  • the output signal of the oxygen concentration sensor 90 is input to the air-fuel ratio calculation unit 101 before the catalyst. Further, the output signal of the air amount sensor 58 is input to the oxygen amount calculation unit 102 before the catalyst.
  • the catalyst diagnosis unit 104 determines that the catalyst device C is in a predetermined deteriorated state, the catalyst diagnosis unit 104 is configured to notify the occupant by an indicator 74 provided in a meter device or the like.
  • the perturbation means 105 executes a patrol process for shifting the air-fuel ratio of the internal combustion engine to the rich side and the lean side.
  • FIG. 5 is a diagram for explaining the responsiveness of the catalyst device C before and after deterioration.
  • the catalyst device C after deterioration has a lower purification rate and a lower oxygen storage capacity than the catalyst device C before deterioration, whereby the response of the oxygen concentration sensor 90 provided downstream of the catalyst becomes faster. ..
  • a lean operation is executed so as to supply an amount of oxygen that can be accumulated in the normal catalyst device C but cannot be accumulated in the deteriorated catalyst device C, and then a rich operation is performed. The rich operation is repeated so as to switch to and release almost all the accumulated oxygen.
  • this perturbation process is executed, the output of the oxygen concentration sensor 90 hardly changes before the catalyst device C deteriorates, but the output of the oxygen concentration sensor 90 changes significantly after the deterioration. It becomes.
  • FIG. 6 is a timing chart when the deterioration diagnosis of the catalyst device C after deterioration is made.
  • FIG. 7 is a timing chart when the deterioration diagnosis of the catalyst device C before deterioration is made.
  • the estimated air-fuel ratio (solid line) on the upstream side of the catalyst device C, the target air-fuel ratio (solid line), and the air-fuel ratio on the downstream side of the catalyst by the oxygen concentration sensor 90 two-point chain line.
  • a coefficient (solid line) indicating the degree of transition to the rich side or lean side in the perturbation process for detecting the degree of deterioration
  • a correction coefficient H broken line
  • the correction coefficient H is controlled by three elements: the deviation between the target air-fuel ratio and the air-fuel ratio on the downstream side of the catalyst by the oxygen concentration sensor 90, and its integration and differentiation. Before deterioration, the difference between the air-fuel ratio on the downstream side of the catalyst by the oxygen concentration sensor 90 and the target air-fuel ratio is relatively large.
  • the downstream side of the catalyst by the oxygen concentration sensor 90 The air-fuel ratio on the side overshoots.
  • the air-fuel ratio on the downstream side of the catalyst by the oxygen concentration sensor 90 follows the target air-fuel ratio faster than that of the new catalyst before deterioration, and overshoot does not occur.
  • 14.5 theoretical air-fuel ratio
  • K coefficient indicating the degree of transition to the rich side or lean side in the perturbation process for detecting the degree of deterioration
  • H target air-fuel ratio and output of the oxygen concentration sensor 90. It is a correction coefficient determined by the signal.
  • O2 the amount of air per cycle.
  • the pre-catalyst oxygen amount integrating unit 103 obtains the oxygen storage capacity (OSR) at the time of rich instruction and the oxygen storage capacity (OSL) at the time of rich instruction by integrating the calculated inflow oxygen amount, and obtains the oxygen storage capacity (OSL) at the time of rich instruction. Perform deterioration diagnosis.
  • OSR oxygen storage capacity
  • OSL oxygen storage capacity
  • the catalyst deterioration diagnostic apparatus As described above, according to the catalyst deterioration diagnostic apparatus according to the present invention, it is based on the oxygen concentration sensor 90 provided on the downstream side of the catalyst device C provided in the exhaust pipe 19 of the engine E and the output signals of the oxygen concentration sensor 90.
  • the control unit 100 for diagnosing the degree of deterioration of the catalyst device C the air-fuel ratio of the air-fuel mixture supplied to the engine E is alternately set toward the target air-fuel ratio set on the rich side and the lean side from the stoichiometric air-fuel ratio.
  • the control unit 100 includes a patrol means 105 that performs a transitional patrol process, and the control unit 100 is in the air on the upstream side of the catalyst device C based on the target air-fuel ratio and the output signal of the oxygen concentration sensor 90 during the perturbation process. Since the fuel ratio is estimated and detected, it is possible to detect the degree of deterioration of the catalyst device C with only one oxygen concentration sensor 90 provided on the downstream side of the catalyst device.
  • the form of the motorcycle, the shape and structure of the catalyst device and the oxygen concentration sensor, the configuration of the control unit, the transition concentration in the patrol processing, etc. are not limited to the above embodiment and can be changed in various ways.
  • the catalyst deterioration diagnostic apparatus according to the present invention can be applied to various internal combustion engines having a catalyst apparatus and an oxygen concentration sensor.

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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
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Abstract

Provided is a catalyst deterioration diagnostic device that is capable of detecting the degree of deterioration of a catalyst device with use of a single oxygen concentration sensor. The catalyst deterioration diagnostic device has: an oxygen concentration sensor (90) that is provided downstream of a catalyst (C) provided to an exhaust pipe (19) of an engine (E); and a control unit (100) that diagnoses the degree of deterioration of the catalyst (C) on the basis of an output signal of the oxygen concentration sensor (90). The catalyst deterioration diagnostic device is provided with: a perturbation means (105) for carrying out a perturbation process in which the air-fuel ratio of an air-fuel mixture fed to the engine (E) is alternately shifted toward target air-fuel ratios that are set on richer and leaner sides compared to a theoretical air-fuel ratio. During the perturbation process, the control unit (100) infers and detects the air-fuel ratio upstream of the catalyst (C) on the basis of the target air-fuel ratios and of the output signal of the oxygen concentration sensor (90).

Description

触媒劣化診断装置Catalyst deterioration diagnostic equipment
 本発明は、触媒劣化診断装置に係り、特に、エンジンの排気管に設けられた触媒装置の劣化度合いを検知する触媒劣化診断装置に関する。 The present invention relates to a catalyst deterioration diagnostic device, and more particularly to a catalyst deterioration diagnostic device that detects the degree of deterioration of the catalyst device provided in the exhaust pipe of an engine.
 従来から、エンジンの排気管に設けられた触媒装置の劣化度合いを検知する触媒劣化診断装置が知られている。 Conventionally, a catalyst deterioration diagnostic device that detects the degree of deterioration of the catalyst device provided in the exhaust pipe of an engine has been known.
 特許文献1には、触媒装置の上流側と下流側にそれぞれ酸素濃度センサを配置し、空燃比をリッチ側およびリーン側に切り換えた際の酸素濃度センサの出力信号の変化に基づいて、触媒装置の劣化度合いを検知する構成が開示されている。 In Patent Document 1, oxygen concentration sensors are arranged on the upstream side and the downstream side of the catalyst device, respectively, and the catalyst device is based on the change in the output signal of the oxygen concentration sensor when the air-fuel ratio is switched between the rich side and the lean side. The configuration for detecting the degree of deterioration of the above is disclosed.
特開2007-285288号公報Japanese Unexamined Patent Publication No. 2007-285288
 しかし、特許文献1の構成では、2つの酸素濃度センサが必要であってコストがかかるため、触媒の劣化度合いを1つの酸素濃度センサで実行する構成が模索されていた。 However, in the configuration of Patent Document 1, two oxygen concentration sensors are required and it is costly, so a configuration in which the degree of deterioration of the catalyst is executed by one oxygen concentration sensor has been sought.
 本発明の目的は、上記従来技術の課題を解決し、1つの酸素濃度センサで触媒装置の劣化度合いを検知することができる触媒劣化診断装置を提供することにある。 An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a catalyst deterioration diagnostic device capable of detecting the degree of deterioration of the catalyst device with one oxygen concentration sensor.
 前記目的を達成するために、本発明は、エンジン(E)の排気管(19)に設けられる触媒(C)の下流側に設けられる酸素濃度センサ(90)と、前記酸素濃度センサ(90)の出力信号に基づいて前記触媒(C)の劣化度合いを診断する制御部(100)とを有する触媒劣化診断装置において、前記エンジン(E)に供給する混合気の空燃比を、理論空燃比よりリッチ側およびリーン側に設定した目標空燃比に向けて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(105)を備え、前記制御部(100)は、前記パータベーション処理の最中に、前記目標空燃比および前記酸素濃度センサ(90)の出力信号に基づいて、前記触媒(C)の上流側の空燃比を推測検知する点に第1の特徴がある。 In order to achieve the above object, the present invention comprises an oxygen concentration sensor (90) provided on the downstream side of the catalyst (C) provided in the exhaust pipe (19) of the engine (E) and the oxygen concentration sensor (90). In a catalyst deterioration diagnosis device having a control unit (100) for diagnosing the degree of deterioration of the catalyst (C) based on the output signal of the above, the air-fuel ratio of the air-fuel mixture supplied to the engine (E) is calculated from the stoichiometric air-fuel ratio. The control unit (100) is provided with a catalyst means (105) for performing a catalyst process that alternately shifts toward the target air-fuel ratio set on the rich side and the lean side, and the control unit (100) is said to be in the middle of the pattern processing. The first feature is that the air-fuel ratio on the upstream side of the catalyst (C) is estimated and detected based on the target air-fuel ratio and the output signal of the oxygen concentration sensor (90).
 また、前記触媒(C)の上流側の空燃比としてのAFRは、理論空燃比を14.5、劣化度合いを検知するためのパータベーション処理におけるリッチ側またはリーン側への推移の度合いを示す係数をK、前記目標空燃比と前記酸素濃度センサ(90)の出力信号とにより決定される補正係数をHとしたときに、以下の演算式 AFR=14.5÷K×H によって求められる点に第2の特徴がある。 Further, the AFR as the air-fuel ratio on the upstream side of the catalyst (C) has a theoretical air-fuel ratio of 14.5, and is a coefficient indicating the degree of transition to the rich side or the lean side in the perturbation treatment for detecting the degree of deterioration. Is K, and the correction coefficient determined by the target air-fuel ratio and the output signal of the oxygen concentration sensor (90) is H. There is a second feature.
 また、前記補正係数は、前記目標空燃比と前記酸素濃度センサ(90)の出力信号との乖離に対してPID制御を行うことにより算出される点に第3の特徴がある。 The third feature is that the correction coefficient is calculated by performing PID control on the deviation between the target air-fuel ratio and the output signal of the oxygen concentration sensor (90).
 また、前記触媒(C)の上流側の流入酸素量としてのO2は、1サイクル当たりの空気量をGAIRとしたときに、以下の演算式 O2=GAIR×(1-14.5÷AFR) によって求められる点に第4の特徴がある。 Further, O2 as the amount of inflow oxygen on the upstream side of the catalyst (C) is calculated by the following formula O2 = GAIR × (1-14.5 ÷ AFR) when the amount of air per cycle is GAIR. There is a fourth feature in what is required.
 さらに、前記制御部(100)は、流入酸素量を積算することで前記触媒(C)の酸素吸着能力を算出し、前記触媒(C)の劣化状態を診断する点に第5の特徴がある。 Further, the control unit (100) has a fifth feature in that it calculates the oxygen adsorption capacity of the catalyst (C) by integrating the amount of inflow oxygen and diagnoses the deteriorated state of the catalyst (C). ..
 第1の特徴によれば、エンジン(E)の排気管(19)に設けられる触媒(C)の下流側に設けられる酸素濃度センサ(90)と、前記酸素濃度センサ(90)の出力信号に基づいて前記触媒(C)の劣化度合いを診断する制御部(100)とを有する触媒劣化診断装置において、前記エンジン(E)に供給する混合気の空燃比を、理論空燃比よりリッチ側およびリーン側に設定した目標空燃比に向けて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(105)を備え、前記制御部(100)は、前記パータベーション処理の最中に、前記目標空燃比および前記酸素濃度センサ(90)の出力信号に基づいて、前記触媒(C)の上流側の空燃比を推測検知するので、触媒の下流側に設けられた1つの酸素濃度センサのみで触媒の劣化度合いを検知することが可能となる。 According to the first feature, the output signals of the oxygen concentration sensor (90) provided on the downstream side of the catalyst (C) provided in the exhaust pipe (19) of the engine (E) and the oxygen concentration sensor (90). In the catalyst deterioration diagnosis apparatus having a control unit (100) for diagnosing the degree of deterioration of the catalyst (C) based on the above, the air-fuel ratio of the air-fuel mixture supplied to the engine (E) is set to be richer and leaner than the stoichiometric air-fuel ratio. The control unit (100) is provided with a catalyst means (105) that performs a catalyst processing that alternately shifts toward a target air-fuel ratio set on the side, and the control unit (100) is capable of performing the target air-fuel ratio and the target air-fuel ratio during the catalyst processing. Since the air-fuel ratio on the upstream side of the catalyst (C) is estimated and detected based on the output signal of the oxygen concentration sensor (90), the degree of deterioration of the catalyst is determined by only one oxygen concentration sensor provided on the downstream side of the catalyst. Can be detected.
 第2の特徴によれば、前記触媒(C)の上流側の空燃比としてのAFRは、理論空燃比を14.5、劣化度合いを検知するためのパータベーション処理におけるリッチ側またはリーン側への推移の度合いを示す係数をK、前記目標空燃比と前記酸素濃度センサ(90)の出力信号とにより決定される補正係数をHとしたときに、以下の演算式 AFR=14.5÷K×H によって求められるので、簡単な演算式によって触媒の上流側の空燃比を算出することが可能となる。 According to the second feature, the AFR as the air-fuel ratio on the upstream side of the catalyst (C) has a theoretical air-fuel ratio of 14.5, and the perturbation treatment for detecting the degree of deterioration has a rich side or a lean side. When the coefficient indicating the degree of transition is K and the correction coefficient determined by the target air-fuel ratio and the output signal of the oxygen concentration sensor (90) is H, the following calculation formula AFR = 14.5 ÷ K × Since it is obtained by H, it is possible to calculate the air-fuel ratio on the upstream side of the catalyst by a simple calculation formula.
 第3の特徴によれば、前記補正係数は、前記目標空燃比と前記酸素濃度センサ(90)の出力信号との乖離に対してPID制御を行うことにより算出されるので、一般的なフィードバック処理を用いて補正係数を算出することが可能となる。 According to the third feature, the correction coefficient is calculated by performing PID control on the deviation between the target air-fuel ratio and the output signal of the oxygen concentration sensor (90), and thus is a general feedback process. It is possible to calculate the correction coefficient using.
 第4の特徴によれば、前記触媒(C)の上流側の流入酸素量としてのO2は、1サイクル当たりの空気量をGAIRとしたときに、以下の演算式 O2=GAIR×(1-14.5÷AFR) によって求められるので、簡単な演算式によって触媒の上流側の流入酸素量を算出することが可能となる。 According to the fourth feature, O2 as the amount of inflow oxygen on the upstream side of the catalyst (C) is calculated by the following formula O2 = GAIR × (1-14) when the amount of air per cycle is GAIR. Since it is calculated by (5.5 ÷ AFR), it is possible to calculate the amount of inflow oxygen on the upstream side of the catalyst by a simple calculation formula.
 第5の特徴によれば、前記制御部(100)は、流入酸素量を積算することで前記触媒(C)の酸素吸着能力を算出し、前記触媒(C)の劣化状態を診断するので、触媒の下流側に設けられた1つの酸素濃度センサのみで触媒の劣化度合いを検知することが可能となる。 According to the fifth feature, the control unit (100) calculates the oxygen adsorption capacity of the catalyst (C) by integrating the amount of inflow oxygen, and diagnoses the deteriorated state of the catalyst (C). It is possible to detect the degree of deterioration of the catalyst with only one oxygen concentration sensor provided on the downstream side of the catalyst.
本発明の一実施形態に係る鞍乗型車両としての自動二輪車の左側面図である。It is a left side view of the motorcycle as a saddle-type vehicle which concerns on one Embodiment of this invention. 排気管の途中に設けられる拡径部の断面図である。It is sectional drawing of the diameter expansion part provided in the middle of an exhaust pipe. エンジンと酸素濃度センサとの関係を示す模式図である。It is a schematic diagram which shows the relationship between an engine and an oxygen concentration sensor. 触媒装置の劣化診断を行う制御部の構成を示すブロック図である。It is a block diagram which shows the structure of the control part which performs the deterioration diagnosis of a catalyst device. 触媒装置の劣化前後の応答性を説明する図である。It is a figure explaining the responsiveness before and after deterioration of a catalyst apparatus. 劣化後の触媒装置を劣化診断したときのタイミングチャートである。It is a timing chart when the deterioration diagnosis of the catalyst device after deterioration is made. 劣化前の触媒装置を劣化診断したときのタイミングチャートである。It is a timing chart when the deterioration diagnosis of the catalyst device before deterioration is made.
 以下、図面を参照して本発明の好ましい実施の形態について詳細に説明する。図1は、本発明の一実施形態に係る鞍乗型車両としての自動二輪車1の左側面図である。鞍乗型車両である自動二輪車1の車体フレーム2の前端には、ステアリングステム10を回動可能に軸支するヘッドパイプ12が取り付けられている。ステアリングステム10の上端には、不図示のトップブリッジを介して操向ハンドル6が取り付けられている。ステアリングステム10と一体に回動するトップブリッジは、ヘッドパイプ12の下部でステアリングステム10に固定される不図示のボトムブリッジと共に左右一対のフロントフォーク16を支持している。フロントフォーク16の下端には、ブレーキディスク35を備えた前輪WFが回動自在に軸支されている。 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a left side view of a motorcycle 1 as a saddle-type vehicle according to an embodiment of the present invention. A head pipe 12 that rotatably supports the steering stem 10 is attached to the front end of the vehicle body frame 2 of the motorcycle 1 which is a saddle-mounted vehicle. A steering handle 6 is attached to the upper end of the steering stem 10 via a top bridge (not shown). The top bridge that rotates integrally with the steering stem 10 supports a pair of left and right front forks 16 together with a bottom bridge (not shown) that is fixed to the steering stem 10 at the lower part of the head pipe 12. A front wheel WF provided with a brake disc 35 is rotatably supported at the lower end of the front fork 16.
 車体フレーム2の下部には、ヘッドパイプ12の後方から下方に延びるハンガフレーム17によってシリンダヘッド18の下部が支持された並列2気筒のエンジンEが配置されている。エンジンEの車幅方向左側には、ジェネレータカバーEaおよびドライブスプロケットカバーEbが取り付けられている。ハンガフレーム17の前方には、エンジン冷却水のラジエータ15が配設されている。 A parallel two-cylinder engine E in which the lower part of the cylinder head 18 is supported by a hanger frame 17 extending downward from the rear of the head pipe 12 is arranged in the lower part of the vehicle body frame 2. A generator cover Ea and a drive sprocket cover Eb are attached to the left side of the engine E in the vehicle width direction. A radiator 15 for engine cooling water is arranged in front of the hanger frame 17.
 車体フレーム2は、エンジンEの上部および後部でエンジンEを支持すると共に、ピボット21によってスイングアーム24を揺動自在に軸支する。ピボット21を軸支するピボットプレート21aの下方には、運転者の足乗せステップ23が左右一対で設けられ、その後方上方のステップブラケット21cには、折り畳み式の同乗者用ステップ21bが配設されている。また、足乗せステップ23の下方には、停車時に自動二輪車1の後輪WRを浮かせて自立させるメインスタンド22と、車体を左側に傾斜させて自立させるサイドスタンド140が取り付けられている。メインスタンド22およびサイドスタンド140は、車体後方側に略90度揺動することで格納状態となる。 The vehicle body frame 2 supports the engine E at the upper and rear parts of the engine E, and the swing arm 24 is swingably supported by the pivot 21. A pair of left and right foot-resting steps 23 for the driver are provided below the pivot plate 21a that pivotally supports the pivot 21, and a foldable passenger step 21b is provided on the step bracket 21c on the rear upper side thereof. ing. Further, below the footrest step 23, a main stand 22 that floats the rear wheel WR of the motorcycle 1 to stand on its own when the vehicle is stopped, and a side stand 140 that tilts the vehicle body to the left to stand on its own are attached. The main stand 22 and the side stand 140 are retracted by swinging about 90 degrees toward the rear side of the vehicle body.
 自動二輪車1の車体下部には、エンジンEの排出ガスを浄化および消音して後方に排出する排気装置20が取り付けられている。排気装置20は、シリンダの排気ポートに接続されて排出ガスを後方へ誘導する排気管19と、排気管19の後端に接続されるマフラ26とを有する。シリンダヘッド18の前方下方には、排気管19の前方および側方を覆う排気管カバー5aが配設されている。ピボット21に軸支されるスイングアーム24は、不図示のリヤクッションによって車体フレーム2に吊り下げられている。スイングアーム24の後端部に回転自在に軸支される後輪WRには、エンジンEの駆動力がドライブチェーン25を介して伝達される。 An exhaust device 20 that purifies and silences the exhaust gas of the engine E and discharges it to the rear is attached to the lower part of the vehicle body of the motorcycle 1. The exhaust device 20 has an exhaust pipe 19 connected to an exhaust port of a cylinder to guide exhaust gas to the rear, and a muffler 26 connected to the rear end of the exhaust pipe 19. An exhaust pipe cover 5a that covers the front and sides of the exhaust pipe 19 is arranged below the front of the cylinder head 18. The swing arm 24 pivotally supported by the pivot 21 is suspended from the vehicle body frame 2 by a rear cushion (not shown). The driving force of the engine E is transmitted to the rear wheel WR, which is rotatably supported by the rear end of the swing arm 24, via the drive chain 25.
 エンジンEの上方で、外装部品であるサイドカウル5に覆われた位置には、大型の開閉リッド3からアクセスする収納ボックス4が設けられている。サイドカウル5の前方にはヘッドライト13が配設されており、ヘッドライト13の上方には、左右一対のフラッシャランプ11およびウインドスクリーン9が配設されている。左右の操向ハンドル6には、ナックルガード8およびバックミラー7がそれぞれ取り付けられている。また、サイドカウル15の下部で、フロントフォーク16の車幅方向外側の位置には、左右一対のフォグランプ14が取り付けられており、前輪WFの上方には、車体への泥はね等を防ぐフロントフェンダ36が取り付けられている。 Above the engine E, a storage box 4 accessed from the large opening / closing lid 3 is provided at a position covered by the side cowl 5, which is an exterior part. A headlight 13 is arranged in front of the side cowl 5, and a pair of left and right flasher lamps 11 and a windscreen 9 are arranged above the headlight 13. A knuckle guard 8 and a rearview mirror 7 are attached to the left and right steering handles 6, respectively. Further, a pair of left and right fog lamps 14 are attached to the lower part of the side cowl 15 at a position outside the front fork 16 in the vehicle width direction, and above the front wheel WF, a front that prevents mud splashing on the vehicle body and the like. A fender 36 is attached.
 車体フレーム2の後方には、燃料タンク28等を支持するリヤフレーム29が取り付けられている。リヤフレーム29の左右はシートカウル31で覆われており、その上部には、運転者シート27および同乗者シート30が配設されている。シートカウル31の後端には尾灯装置32が取り付けられており、シートカウル31から後方下方に延びるリヤフェンダ34には、後側のフラッシャランプ33が支持されている。 A rear frame 29 that supports the fuel tank 28 and the like is attached to the rear of the vehicle body frame 2. The left and right sides of the rear frame 29 are covered with seat cowls 31, and a driver's seat 27 and a passenger's seat 30 are arranged above the seat cowl 31. A taillight device 32 is attached to the rear end of the seat cowl 31, and a rear flasher lamp 33 is supported by a rear fender 34 extending rearward and downward from the seat cowl 31.
 図2は、排気管19の途中に設けられる拡径部61の断面図である。拡径部61には触媒装置Cが収容されており、触媒装置Cの後方に空燃比センサ80が配設されている。拡径部61は、前側外筒76の内側にパッキン75を介して触媒装置Cを保持すると共に、触媒装置Cおよび前側外筒76の後端部を、漏斗状の後側外筒78の外周面に対して、溶接ビードBで溶接固定することで構成される。空燃比センサ90は、後側外筒78に溶接固定された取付ボスとしての台座86に螺合することで保持される。 FIG. 2 is a cross-sectional view of the enlarged diameter portion 61 provided in the middle of the exhaust pipe 19. The catalyst device C is housed in the enlarged diameter portion 61, and the air-fuel ratio sensor 80 is arranged behind the catalyst device C. The enlarged diameter portion 61 holds the catalyst device C inside the front outer cylinder 76 via the packing 75, and the rear end portion of the catalyst device C and the front outer cylinder 76 is formed on the outer periphery of the funnel-shaped rear outer cylinder 78. It is configured by welding and fixing with a welding bead B to the surface. The air-fuel ratio sensor 90 is held by being screwed into a pedestal 86 as a mounting boss welded and fixed to the rear outer cylinder 78.
 空燃比センサ90は、酸素濃度の変化をリニアに検出できるLAFセンサか、または、理論空燃比を境に出力値が反転することで理論空燃比にあることのみを検知できるO2センサとすることができる。また、酸素濃度センサ90は、制御部100によって制御されるヒータによって最適な温度管理がなされるヒータ付きセンサとすることができる。 The air-fuel ratio sensor 90 may be a LAF sensor that can linearly detect changes in oxygen concentration, or an O2 sensor that can only detect that the air-fuel ratio is at the theoretical air-fuel ratio by reversing the output value at the boundary of the theoretical air-fuel ratio. can. Further, the oxygen concentration sensor 90 can be a sensor with a heater whose temperature is optimally controlled by a heater controlled by the control unit 100.
 図3は、エンジンEと酸素濃度センサ90との関係を示す模式図である。排気装置20は、触媒装置Cの下流側に位置する酸素濃度センサ90を有している。エンジンEの吸気管56には、燃料噴射装置であるインジェクタ57が設けられており、その上流には、吸入空気量センサ55が配設されている。吸入空気量センサ55のセンサ信号は、空気量検知部58に入力される。インジェクタ制御部59は、スロットル操作やエンジン回転数の情報に加え、空気量検知部58および制御部100からの信号に基づいて、適切な空燃比で燃焼が行われるようにインジェクタ57を制御する。 FIG. 3 is a schematic diagram showing the relationship between the engine E and the oxygen concentration sensor 90. The exhaust device 20 has an oxygen concentration sensor 90 located on the downstream side of the catalyst device C. An injector 57, which is a fuel injection device, is provided in the intake pipe 56 of the engine E, and an intake air amount sensor 55 is arranged upstream of the injector 57. The sensor signal of the intake air amount sensor 55 is input to the air amount detection unit 58. The injector control unit 59 controls the injector 57 so that combustion is performed at an appropriate air-fuel ratio based on signals from the air amount detection unit 58 and the control unit 100 in addition to information on throttle operation and engine speed.
 通常、触媒装置Cの劣化診断は、触媒装置Cの上流側に設けられる酸素濃度センサと、触媒装置Cの下流側に設けられる酸素濃度センサの2つのセンサによって行われる。具体的には、上流側酸素濃度センサのセンサ出力と下流側酸素濃度センサのセンサ出力との関係性に着目し、触媒装置Cの劣化に伴う変化を検知して行われる。例えば、触媒装置Cの劣化に伴う酸素の吸着速度の低下に着目した方法では、下流側酸素濃度センサの出力に基づいて空燃比をフィードバック制御する場合、フィードバック制御により排出ガス中の酸素濃度が変化するまでの応答時間が劣化の影響を受けて変化するため、下流側酸素濃度センサの出力の変化周期が予め定められた触媒劣化条件に該当するか否かを判定することで、触媒の劣化状態を判定できる。具体的には、所定時間内に下流側酸素濃度センサが所定の変動を行う回数をカウントするカウント法を用いることができる。 Normally, the deterioration diagnosis of the catalyst device C is performed by two sensors, an oxygen concentration sensor provided on the upstream side of the catalyst device C and an oxygen concentration sensor provided on the downstream side of the catalyst device C. Specifically, attention is paid to the relationship between the sensor output of the upstream oxygen concentration sensor and the sensor output of the downstream oxygen concentration sensor, and the change due to the deterioration of the catalyst device C is detected. For example, in the method focusing on the decrease in the oxygen adsorption rate due to the deterioration of the catalyst device C, when the air-fuel ratio is feedback-controlled based on the output of the downstream oxygen concentration sensor, the oxygen concentration in the exhaust gas changes due to the feedback control. Since the response time until the reaction changes due to the influence of deterioration, the deterioration state of the catalyst is determined by determining whether or not the change cycle of the output of the downstream oxygen concentration sensor corresponds to the predetermined catalyst deterioration conditions. Can be determined. Specifically, a counting method can be used in which the number of times the downstream oxygen concentration sensor makes a predetermined fluctuation within a predetermined time is counted.
 このような劣化診断処理は、内燃機関の空燃比をリッチ側およびリーン側に交互に推移させるパータベーション処理を伴って実行される。具体的には、空燃比をリーン側に切り換え、下流側酸素濃度センサの値が所定値に到達するまでの間に、上流側酸素濃度センサを用いて積算される酸素量が閾値を超えるかどうかの観測を行い、次いで、空燃比をリッチ側に切り換え、下流側酸素濃度センサの値が所定値に到達するまでの間に、上流側酸素濃度センサを用いて積算される酸素量が閾値を超えるかどうか観測を行う、という動作を繰り返すことで触媒装置Cの劣化を検知する。このようなパータベーション処理を行ったとき、正常な触媒装置Cであれば蓄積可能だが、劣化した触媒装置Cであれば蓄積できない程度の量の酸素を供給するようにリーン運転を実行し、その後リッチ運転に切り替えて蓄積した酸素をほぼすべて放出するようにリッチ運転を実行する。そうすると、触媒装置Cが劣化していなければ、酸素濃度センサ90の出力がほとんど変化しないが、劣化している場合は、酸素濃度センサ90の出力が大きく変化することで、劣化診断が可能となる。 Such deterioration diagnosis processing is executed with a patrol processing in which the air-fuel ratio of the internal combustion engine is alternately changed to the rich side and the lean side. Specifically, whether or not the amount of oxygen accumulated using the upstream oxygen concentration sensor exceeds the threshold value until the value of the downstream oxygen concentration sensor reaches a predetermined value by switching the air fuel ratio to the lean side. Then, the air-fuel ratio is switched to the rich side, and the amount of oxygen accumulated using the upstream oxygen concentration sensor exceeds the threshold value until the value of the downstream oxygen concentration sensor reaches a predetermined value. Deterioration of the catalyst device C is detected by repeating the operation of observing whether or not. When such a perturbation treatment is performed, a lean operation is executed so as to supply an amount of oxygen that can be accumulated in the normal catalyst device C but cannot be accumulated in the deteriorated catalyst device C, and then the lean operation is executed. Switch to the rich operation and execute the rich operation so as to release almost all the accumulated oxygen. Then, if the catalyst device C is not deteriorated, the output of the oxygen concentration sensor 90 hardly changes, but if it is deteriorated, the output of the oxygen concentration sensor 90 changes significantly, so that the deterioration diagnosis becomes possible. ..
 本実施形態では、触媒装置Cの上流側に酸素濃度センサを有しないため、下流側酸素濃度センサの出力に基づいて触媒装置Cの上流側の酸素濃度を推測検知し、この推測検知した値に基づいて触媒装置Cの劣化診断を行う点に特徴がある。 In the present embodiment, since the oxygen concentration sensor is not provided on the upstream side of the catalyst device C, the oxygen concentration on the upstream side of the catalyst device C is estimated and detected based on the output of the downstream oxygen concentration sensor, and the estimated detected value is used. It is characterized in that deterioration diagnosis of the catalyst device C is performed based on the above.
 図4は、触媒装置Cの劣化診断を行う制御部100の構成を示すブロック図である。制御部100は、パータベーション手段105と、触媒前空燃比算出部101と、触媒前酸素量算出部と、触媒前酸素量積算部103と、触媒診断部104とを含む。触媒前空燃比算出部101には、酸素濃度センサ90の出力信号が入力される。また、触媒前酸素量算出部102には、空気量センサ58の出力信号が入力される。触媒診断部104は、触媒装置Cが所定の劣化状態にあると判断すると、メータ装置等に設けられたインジケータ74によって乗員に報知するように構成されている。 FIG. 4 is a block diagram showing a configuration of a control unit 100 that diagnoses deterioration of the catalyst device C. The control unit 100 includes a perturbation means 105, a catalyst pre-catalyst air-fuel ratio calculation unit 101, a pre-catalyst oxygen amount calculation unit, a pre-catalyst oxygen amount integration unit 103, and a catalyst diagnosis unit 104. The output signal of the oxygen concentration sensor 90 is input to the air-fuel ratio calculation unit 101 before the catalyst. Further, the output signal of the air amount sensor 58 is input to the oxygen amount calculation unit 102 before the catalyst. When the catalyst diagnosis unit 104 determines that the catalyst device C is in a predetermined deteriorated state, the catalyst diagnosis unit 104 is configured to notify the occupant by an indicator 74 provided in a meter device or the like.
 パータベーション手段105は、内燃機関の空燃比をリッチ側およびリーン側に推移させるパータベーション処理を実行する。触媒前空燃比算出部101は、触媒装置Cの上流側の空燃比としてのAFRを、AFR=14.5÷K×Hの演算式によって求める。 The perturbation means 105 executes a patrol process for shifting the air-fuel ratio of the internal combustion engine to the rich side and the lean side. The catalyst front air-fuel ratio calculation unit 101 obtains the AFR as the air-fuel ratio on the upstream side of the catalyst device C by the calculation formula of AFR = 14.5 ÷ K × H.
 図5は、触媒装置Cの劣化前後の応答性を説明する図である。劣化後の触媒装置Cは、劣化前の触媒装置Cに対して、浄化率が低下すると共に酸素貯蔵能力が低下し、これにより、触媒の下流に設けられた酸素濃度センサ90の応答が早くなる。前記したように、パータベーション処理は、正常な触媒装置Cであれば蓄積可能だが劣化した触媒装置Cであれば蓄積できない程度の量の酸素を供給するようにリーン運転を実行し、その後リッチ運転に切り替えて蓄積した酸素をほぼすべて放出するようにリッチ運転を実行することを繰り返すものである。このパータベーション処理を実行すると、触媒装置Cが劣化前であれば酸素濃度センサ90の出力がほとんど変化しないが、劣化後であれば、酸素濃度センサ90の出力が大きく変化するという差異が生じることとなる。 FIG. 5 is a diagram for explaining the responsiveness of the catalyst device C before and after deterioration. The catalyst device C after deterioration has a lower purification rate and a lower oxygen storage capacity than the catalyst device C before deterioration, whereby the response of the oxygen concentration sensor 90 provided downstream of the catalyst becomes faster. .. As described above, in the perturbation treatment, a lean operation is executed so as to supply an amount of oxygen that can be accumulated in the normal catalyst device C but cannot be accumulated in the deteriorated catalyst device C, and then a rich operation is performed. The rich operation is repeated so as to switch to and release almost all the accumulated oxygen. When this perturbation process is executed, the output of the oxygen concentration sensor 90 hardly changes before the catalyst device C deteriorates, but the output of the oxygen concentration sensor 90 changes significantly after the deterioration. It becomes.
 図6は、劣化後の触媒装置Cを劣化診断したときのタイミングチャートである。また、図7は劣化前の触媒装置Cを劣化診断したときのタイミングチャートである。両タイムチャートでは、上から順に、推定される触媒装置Cの上流側の空燃比(実線)、目標空燃比(実線)、酸素濃度センサ90による触媒の下流側の空燃比(2点鎖線)、劣化度合いを検知するためのパータベーション処理におけるリッチ側またはリーン側への推移の度合いを示す係数(実線)、目標空燃比と酸素濃度センサ90の出力信号とにより決定される補正係数H(破線)、リッチ指示時の酸素貯蔵能力(OSR)と、リッチ指示時の酸素貯蔵能力(OSL)(実線)、触媒装置Cの上流側の流入酸素量としてのO2量(1点鎖線)を示している。本実施形態では、補正係数Hの制御を、目標空燃比と酸素濃度センサ90による触媒の下流側の空燃比との偏差、その積分および微分の3つの要素によって行う。劣化前は、酸素濃度センサ90による触媒の下流側の空燃比と目標空燃比との乖離が比較的大きいため、それを調整するために補正係数Hを大きくすると、酸素濃度センサ90による触媒の下流側の空燃比がオーバーシュートする。劣化後のNG触媒では、目標空燃比に対する酸素濃度センサ90による触媒の下流側の空燃比の追従が劣化前の新品触媒より早くなり、オーバーシュートも発生しなくなる。 FIG. 6 is a timing chart when the deterioration diagnosis of the catalyst device C after deterioration is made. Further, FIG. 7 is a timing chart when the deterioration diagnosis of the catalyst device C before deterioration is made. In both time charts, in order from the top, the estimated air-fuel ratio (solid line) on the upstream side of the catalyst device C, the target air-fuel ratio (solid line), and the air-fuel ratio on the downstream side of the catalyst by the oxygen concentration sensor 90 (two-point chain line). A coefficient (solid line) indicating the degree of transition to the rich side or lean side in the perturbation process for detecting the degree of deterioration, and a correction coefficient H (broken line) determined by the target air-fuel ratio and the output signal of the oxygen concentration sensor 90. , Oxygen storage capacity (OSR) at the time of rich instruction, oxygen storage capacity (OSL) (solid line) at the time of rich instruction, and O2 amount (single point chain line) as the inflow oxygen amount on the upstream side of the catalyst device C are shown. .. In the present embodiment, the correction coefficient H is controlled by three elements: the deviation between the target air-fuel ratio and the air-fuel ratio on the downstream side of the catalyst by the oxygen concentration sensor 90, and its integration and differentiation. Before deterioration, the difference between the air-fuel ratio on the downstream side of the catalyst by the oxygen concentration sensor 90 and the target air-fuel ratio is relatively large. Therefore, if the correction coefficient H is increased to adjust it, the downstream side of the catalyst by the oxygen concentration sensor 90 The air-fuel ratio on the side overshoots. In the deteriorated NG catalyst, the air-fuel ratio on the downstream side of the catalyst by the oxygen concentration sensor 90 follows the target air-fuel ratio faster than that of the new catalyst before deterioration, and overshoot does not occur.
 触媒装置Cの上流側の空燃比としてのAFRを、AFR=14.5÷K×Hの演算式によって求める。このとき、14.5:理論空燃比、K:劣化度合いを検知するためのパータベーション処理におけるリッチ側またはリーン側への推移の度合いを示す係数、H:目標空燃比と酸素濃度センサ90の出力信号とにより決定される補正係数、とされる。 The AFR as the air-fuel ratio on the upstream side of the catalyst device C is calculated by the formula of AFR = 14.5 ÷ K × H. At this time, 14.5: theoretical air-fuel ratio, K: coefficient indicating the degree of transition to the rich side or lean side in the perturbation process for detecting the degree of deterioration, H: target air-fuel ratio and output of the oxygen concentration sensor 90. It is a correction coefficient determined by the signal.
 具体的には、図6のt=Aにおいては、パータベーション処理の2.5%リッチ指示時は、K=1.025となり、H=0.99となる。補正係数Hは、目標空燃比との乖離に対してPID制御を行うことにより算出される。これにより、一般的なフィードバック処理を用いて補正係数を算出することが可能となる。
以上より、AFR=14.5÷1.025×0.99=14.005となる。
Specifically, at t = A in FIG. 6, K = 1.025 and H = 0.99 at the time of the 2.5% rich instruction of the perturbation process. The correction coefficient H is calculated by performing PID control with respect to the deviation from the target air-fuel ratio. This makes it possible to calculate the correction coefficient using general feedback processing.
From the above, AFR = 14.5 ÷ 1.025 × 0.99 = 14.005.
 一方、図6の時点Bにおいては、パータベーション処理の2.5%リーン指示時は、K=0.975となり、H=1.01となる。以上より、AFR=14.5÷0.975×1.01=15.02となる。以上より、AFR=14.5÷K×Hの演算式によって触媒装置Cの上流側の空燃比が算出される。 On the other hand, at the time point B in FIG. 6, K = 0.975 and H = 1.01 when the 2.5% lean instruction of the perturbation process is performed. From the above, AFR = 14.5 ÷ 0.975 × 1.01 = 15.02. From the above, the air-fuel ratio on the upstream side of the catalyst device C is calculated by the formula of AFR = 14.5 ÷ K × H.
 次に、触媒前酸素量算出部102は、触媒装置Cの上流側の流入酸素量としてのO2を、O2=GAIR×(1-14.5÷AFR)の演算式によって求める。このとき、GAIR:1サイクル当たりの空気量、とされる。 Next, the pre-catalyst oxygen amount calculation unit 102 obtains O2 as the inflow oxygen amount on the upstream side of the catalyst device C by the formula of O2 = GAIR × (1-14.5 ÷ AFR). At this time, GAIR: the amount of air per cycle.
 具体的には、図6の時点Aにおいては、AGAIR:1mgで、パータベーション処理の2.5%リッチ指示時は、AFR:14.005の場合、O2=1×(1-14.5÷14.005)=-0.0353mgとなる(リッチ時は還元側のためマイナスとなる)。 Specifically, at the time point A in FIG. 6, AGAIR: 1 mg, and when the 2.5% rich instruction of the perturbation treatment is given, when AFR: 14.005, O2 = 1 × (1-14.5 ÷). 14.005) = -0.0353 mg (when rich, it is negative because it is on the reducing side).
 一方、図6の時点Bにおいては、パータベーション処理の2.5%リーン指示時は、AFR:15.02の場合、O2=1×(1-14.5÷15.02)=0.0346mgとなる。以上より、O2=GAIR×(1-14.5÷AFR)の演算式によって触媒装置Cの上流側の流入酸素量が算出される。 On the other hand, at time point B in FIG. 6, when the 2.5% lean instruction of the perturbation treatment is given, in the case of AFR: 15.02, O2 = 1 × (1-14.5 ÷ 15.02) = 0.0346 mg. Will be. From the above, the amount of inflow oxygen on the upstream side of the catalyst device C is calculated by the calculation formula of O2 = GAIR × (1-14.5 ÷ AFR).
 触媒前酸素量積算部103は、算出された流入酸素量を積算することで、リッチ指示時の酸素貯蔵能力(OSR)と、リッチ指示時の酸素貯蔵能力(OSL)を求め、触媒装置Cの劣化診断を行う。 The pre-catalyst oxygen amount integrating unit 103 obtains the oxygen storage capacity (OSR) at the time of rich instruction and the oxygen storage capacity (OSL) at the time of rich instruction by integrating the calculated inflow oxygen amount, and obtains the oxygen storage capacity (OSL) at the time of rich instruction. Perform deterioration diagnosis.
 上記したように、本発明に係る触媒劣化診断装置によれば、エンジンEの排気管19に設けられる触媒装置Cの下流側に設けられる酸素濃度センサ90と、酸素濃度センサ90の出力信号に基づいて触媒装置Cの劣化度合いを診断する制御部100とを有するにおいて、エンジンEに供給する混合気の空燃比を、理論空燃比よりリッチ側およびリーン側に設定した目標空燃比に向けて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105を備え、制御部100は、パータベーション処理の最中に、目標空燃比および酸素濃度センサ90の出力信号に基づいて、触媒装置Cの上流側の空燃比を推測検知するので、触媒装置の下流側に設けられた1つの酸素濃度センサ90のみで触媒装置Cの劣化度合いを検知することが可能となる。 As described above, according to the catalyst deterioration diagnostic apparatus according to the present invention, it is based on the oxygen concentration sensor 90 provided on the downstream side of the catalyst device C provided in the exhaust pipe 19 of the engine E and the output signals of the oxygen concentration sensor 90. In the control unit 100 for diagnosing the degree of deterioration of the catalyst device C, the air-fuel ratio of the air-fuel mixture supplied to the engine E is alternately set toward the target air-fuel ratio set on the rich side and the lean side from the stoichiometric air-fuel ratio. The control unit 100 includes a patrol means 105 that performs a transitional patrol process, and the control unit 100 is in the air on the upstream side of the catalyst device C based on the target air-fuel ratio and the output signal of the oxygen concentration sensor 90 during the perturbation process. Since the fuel ratio is estimated and detected, it is possible to detect the degree of deterioration of the catalyst device C with only one oxygen concentration sensor 90 provided on the downstream side of the catalyst device.
 なお、自動二輪車の形態、触媒装置や酸素濃度センサの形状や構造、制御部の構成、パータベーション処理における推移濃度等は、上記実施形態に限られず、種々の変更が可能である。本発明に係る触媒劣化診断装置は、触媒装置および酸素濃度センサを有する種々の内燃機関に適用することが可能である。 The form of the motorcycle, the shape and structure of the catalyst device and the oxygen concentration sensor, the configuration of the control unit, the transition concentration in the patrol processing, etc. are not limited to the above embodiment and can be changed in various ways. The catalyst deterioration diagnostic apparatus according to the present invention can be applied to various internal combustion engines having a catalyst apparatus and an oxygen concentration sensor.
 1…自動二輪車、19…排気管、74…インジケータ、90…酸素濃度センサ、100…制御部、101…触媒前空燃比算出部、102…触媒前酸素量算出部、103…触媒前酸素量積算部、104…触媒診断部、105…パータベーション手段、E…エンジン、C…触媒装置、AFR…触媒装置の上流側の空燃比、K…パータベーション処理におけるリッチ側またはリーン側への推移の度合いを示す係数、H…目標空燃比と酸素濃度センサの出力信号とにより決定される補正係数、O2…触媒装置の上流側の流入酸素量、GAIR…1サイクル当たりの空気量 1 ... Motorcycle, 19 ... Exhaust pipe, 74 ... Indicator, 90 ... Oxygen concentration sensor, 100 ... Control unit, 101 ... Pre-catalyst air-fuel ratio calculation unit, 102 ... Pre-catalyst oxygen amount calculation unit, 103 ... Pre-catalyst oxygen amount integration Part, 104 ... Catalyst diagnosis unit, 105 ... Perturbation means, E ... Engine, C ... Catalyst device, AFR ... Air-fuel ratio on the upstream side of the catalyst device, K ... Degree of transition to the rich side or lean side in the perturbation process. Factor indicating, H ... Correction coefficient determined by the target air-fuel ratio and the output signal of the oxygen concentration sensor, O2 ... Amount of inflow oxygen on the upstream side of the catalyst device, GAIR ... Amount of air per cycle

Claims (5)

  1.  エンジン(E)の排気管(19)に設けられる触媒(C)の下流側に設けられる酸素濃度センサ(90)と、前記酸素濃度センサ(90)の出力信号に基づいて前記触媒(C)の劣化度合いを診断する制御部(100)とを有する触媒劣化診断装置において、
     前記エンジン(E)に供給する混合気の空燃比を、理論空燃比よりリッチ側およびリーン側に設定した目標空燃比に向けて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(105)を備え、
     前記制御部(100)は、前記パータベーション処理の最中に、前記目標空燃比および前記酸素濃度センサ(90)の出力信号に基づいて、前記触媒(C)の上流側の空燃比を推測検知することを特徴とする触媒劣化診断装置。
    The oxygen concentration sensor (90) provided on the downstream side of the catalyst (C) provided in the exhaust pipe (19) of the engine (E) and the catalyst (C) based on the output signals of the oxygen concentration sensor (90). In a catalyst deterioration diagnostic apparatus having a control unit (100) for diagnosing the degree of deterioration,
    The engine (E) is provided with a patrol means (105) for performing a patrol process in which the air-fuel ratio of the air-fuel mixture supplied to the engine (E) is alternately changed toward the target air-fuel ratio set on the rich side and the lean side from the stoichiometric air-fuel ratio. ,
    During the perturbation process, the control unit (100) estimates and detects the air-fuel ratio on the upstream side of the catalyst (C) based on the target air-fuel ratio and the output signal of the oxygen concentration sensor (90). A catalyst deterioration diagnostic device characterized by
  2.  前記触媒(C)の上流側の空燃比としてのAFRは、理論空燃比を14.5、劣化度合いを検知するためのパータベーション処理におけるリッチ側またはリーン側への推移の度合いを示す係数をK、前記目標空燃比と前記酸素濃度センサ(90)の出力信号とにより決定される補正係数をHとしたときに、以下の演算式
     AFR=14.5÷K×H
     によって求められることを特徴とする請求項1に記載の触媒劣化診断装置。
    The AFR as the air-fuel ratio on the upstream side of the catalyst (C) has a theoretical air-fuel ratio of 14.5 and a coefficient indicating the degree of transition to the rich side or lean side in the perturbation treatment for detecting the degree of deterioration. When the correction coefficient determined by the target air-fuel ratio and the output signal of the oxygen concentration sensor (90) is H, the following calculation formula AFR = 14.5 ÷ K × H
    The catalyst deterioration diagnostic apparatus according to claim 1, wherein the catalyst deterioration diagnostic apparatus is required.
  3.  前記補正係数は、前記目標空燃比と前記酸素濃度センサ(90)の出力信号との乖離に対してPID制御を行うことにより算出されることを特徴とする請求項2に記載の触媒劣化診断装置。 The catalyst deterioration diagnostic apparatus according to claim 2, wherein the correction coefficient is calculated by performing PID control on a deviation between the target air-fuel ratio and the output signal of the oxygen concentration sensor (90). ..
  4.  前記触媒(C)の上流側の流入酸素量としてのO2は、1サイクル当たりの空気量をGAIRとしたときに、以下の演算式
     O2=GAIR×(1-14.5÷AFR)
     によって求められることを特徴とする請求項2または3に記載の触媒劣化診断装置。
    O2 as the amount of inflow oxygen on the upstream side of the catalyst (C) is calculated by the following formula O2 = GAIR × (1-14.5 ÷ AFR) when the amount of air per cycle is GAIR.
    The catalyst deterioration diagnostic apparatus according to claim 2 or 3, wherein the catalyst deterioration diagnostic apparatus is obtained.
  5.  前記制御部(100)は、流入酸素量を積算することで前記触媒(C)の酸素吸着能力を算出し、前記触媒(C)の劣化状態を診断することを特徴とする請求項4に記載の触媒劣化診断装置。 The fourth aspect of claim 4, wherein the control unit (100) calculates the oxygen adsorption capacity of the catalyst (C) by integrating the amount of inflow oxygen and diagnoses the deteriorated state of the catalyst (C). Catalyst deterioration diagnostic equipment.
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JPWO2021176671A1 (en) 2021-09-10
JP7372440B2 (en) 2023-10-31

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