WO2018221528A1 - Dispositif de commande de capteur de gaz - Google Patents

Dispositif de commande de capteur de gaz Download PDF

Info

Publication number
WO2018221528A1
WO2018221528A1 PCT/JP2018/020595 JP2018020595W WO2018221528A1 WO 2018221528 A1 WO2018221528 A1 WO 2018221528A1 JP 2018020595 W JP2018020595 W JP 2018020595W WO 2018221528 A1 WO2018221528 A1 WO 2018221528A1
Authority
WO
WIPO (PCT)
Prior art keywords
cell
sensor
monitor cell
monitor
deterioration
Prior art date
Application number
PCT/JP2018/020595
Other languages
English (en)
Japanese (ja)
Inventor
勇樹 村山
忠勝 小薮
竜三 加山
Original Assignee
株式会社デンソー
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社デンソー filed Critical 株式会社デンソー
Priority to DE112018002768.6T priority Critical patent/DE112018002768T5/de
Publication of WO2018221528A1 publication Critical patent/WO2018221528A1/fr

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/417—Systems using cells, i.e. more than one cell and probes with solid electrolytes
    • G01N27/419—Measuring voltages or currents with a combination of oxygen pumping cells and oxygen concentration cells
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F01N2560/021—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting ammonia NH3
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F01N2560/022—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting CO or CO2
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F01N2560/023—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting HC
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F01N2560/026—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting NOx
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/04—Methods of control or diagnosing
    • F01N2900/0416—Methods of control or diagnosing using the state of a sensor, e.g. of an exhaust gas sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
    • F01N2900/1402—Exhaust gas composition
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4073—Composition or fabrication of the solid electrolyte
    • G01N27/4074—Composition or fabrication of the solid electrolyte for detection of gases other than oxygen
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • This disclosure relates to a gas sensor control device.
  • a NOx sensor that detects NOx (nitrogen oxide) concentration is known as a gas sensor that detects the concentration of a specific gas component in a gas to be detected such as exhaust gas from an internal combustion engine.
  • the NOx sensor has a three-cell structure composed of a pump cell, a monitor cell, and a sensor cell as described in Patent Document 1, for example, and the pump cell discharges or pumps out oxygen in the exhaust gas introduced into the gas chamber.
  • the monitor cell detects the residual oxygen concentration in the gas chamber after passing through the pump cell, and the sensor cell detects the NOx concentration from the gas after passing through the pump cell.
  • Patent Document 1 forcibly switches the applied voltage to the pump cell, and determines the deterioration of the NOx sensor based on the change amount of the sensor cell output at this time. A method for diagnosing is disclosed.
  • the concentration of the specific gas component is calculated by subtracting the monitor cell output from the sensor cell output.
  • the concentration of the specific gas component is calculated based on the difference between the sensor cell output and the monitor cell output, there is a concern that the accuracy of detecting the concentration of the specific gas component may decrease with the deterioration of the monitor cell. In this respect, there is still room for improvement in the existing technology.
  • This indication is made in view of the above-mentioned subject, and the main purpose is to provide the gas sensor control device which can judge the deterioration state of a monitor cell appropriately in the gas sensor which has a pump cell, a sensor cell, and a monitor cell. is there.
  • a control device that is applied to a gas sensor having a monitor cell that detects an oxygen concentration and performs control related to the gas sensor,
  • a pump cell control unit for adjusting the residual oxygen concentration by the pump cell in order to control the output of the monitor cell to a target value;
  • an acquisition unit that acquires the output of the sensor cell;
  • a deterioration determination unit that determines a deterioration state of the monitor cell based on the output of the sensor cell acquired by the acquisition unit; Is provided.
  • the residual oxygen concentration in the gas chamber is adjusted by the pump cell.
  • the concentration of the specific gas component is detected by the sensor cell, and the residual oxygen concentration is detected by the monitor cell.
  • the concentration of the specific gas component is calculated from the difference between the sensor cell output and the monitor cell output, the detection accuracy of the residual oxygen concentration decreases with the deterioration of the monitor cell, which affects the detection of the concentration of the specific gas component. It is thought that it reaches. Therefore, it is considered important to grasp the deterioration state of the monitor cell.
  • the residual oxygen concentration is adjusted by the pump cell so as to control the output of the monitor cell to the target value, and the output of the sensor cell is acquired in a state where the residual oxygen concentration is adjusted.
  • the deterioration state of the monitor cell is determined. If the monitor cell has deteriorated, the residual oxygen concentration in the gas chamber becomes too large or too small in a state where the monitor cell output is controlled to the target value, and the sensor cell output fluctuates due to the influence. The state can be determined. As a result, it is possible to appropriately determine the deterioration state of the monitor cell in the gas sensor having the pump cell, the sensor cell, and the monitor cell.
  • FIG. 1 is a diagram showing a system configuration of an engine exhaust system.
  • FIG. 2 is a cross-sectional view showing the configuration of the NOx sensor
  • FIG. 3 is a cross-sectional view showing a III-III cross section of FIG.
  • FIG. 4 is a functional block diagram of the SCU and ECU.
  • 5A is a diagram showing electromotive force characteristics of a monitor cell
  • FIG. 5B is a diagram showing electromotive force characteristics in a deteriorated state
  • FIG. 5C is an enlarged view of an X portion of FIG. 5B.
  • FIG. 6 is a time chart showing changes in sensor cell current accompanying the start of electromotive force feedback control.
  • FIG. 7 is a flowchart showing a processing procedure for sensor deterioration determination in the case of performing electromotive force feedback control.
  • FIG. 8A is a diagram showing a relationship between the output ratio and the deterioration rate of the monitor cell, and
  • FIG. 8B is a diagram showing a relationship between the output ratio and the deterioration rate of the sensor cell.
  • FIG. 9 is a diagram showing current characteristics of the monitor cell
  • FIG. 10 is a time chart showing changes in sensor cell current accompanying the start of current feedback control.
  • FIG. 11 is a flowchart showing a processing procedure for sensor deterioration determination when current feedback control is performed.
  • FIG. 11 is a flowchart showing a processing procedure for sensor deterioration determination when current feedback control is performed.
  • FIG. 12 is a diagram showing a relationship between electromotive force feedback control and current feedback control, and monitor cell deterioration and sensor cell deterioration.
  • FIG. 13 is a flowchart showing a processing procedure for sensor deterioration determination in the case of performing electromotive force feedback control and current feedback control.
  • FIG. 14 is a diagram for explaining changes in the transient characteristics of the sensor cell output accompanying the deterioration of the sensor cell.
  • FIG. 15 is a flowchart showing the deterioration determination process in the second embodiment.
  • FIG. 16 is a cross-sectional view showing the configuration of another NOx sensor.
  • This embodiment embodies a gas sensor control device that performs control related to a NOx sensor in a system in which exhaust gas discharged from an on-board diesel engine is detected gas and the NOx concentration in the exhaust gas is detected by a NOx sensor. It is said.
  • parts that are the same or equivalent to each other are given the same reference numerals in the drawings, and the description of the same reference numerals is used.
  • an exhaust gas purification system that purifies exhaust gas is provided on the exhaust side of an engine 10 that is a diesel engine.
  • an exhaust pipe 11 that forms an exhaust passage is connected to the engine 10
  • an oxidation catalytic converter 12 and a selective catalytic reduction converter (hereinafter referred to as SCR) are connected to the exhaust pipe 11 in order from the engine 10 side. 13) (referred to as a catalytic converter).
  • the oxidation catalyst converter 12 includes a diesel oxidation catalyst 14 and a DPF (Diesel Particulate Filter) 15.
  • the SCR catalytic converter 13 has an SCR catalyst 16 as a selective reduction type catalyst.
  • a urea water addition valve 17 for adding and supplying urea water (urea aqueous solution) as a reducing agent into the exhaust pipe 11 is provided between the oxidation catalytic converter 12 and the SCR catalytic converter 13 in the exhaust pipe 11. ing.
  • the diesel oxidation catalyst 14 is mainly composed of a ceramic carrier, an oxide mixture containing aluminum oxide, cerium dioxide and zirconium dioxide as components, and a noble metal catalyst such as platinum, palladium and rhodium.
  • the diesel oxidation catalyst 14 oxidizes and purifies hydrocarbons, carbon monoxide, nitrogen oxides and the like contained in the exhaust gas. Further, the diesel oxidation catalyst 14 raises the exhaust temperature by heat generated during the catalytic reaction.
  • the DPF 15 is formed of a honeycomb structure, and is configured by supporting a platinum group catalyst such as platinum or palladium on a porous ceramic.
  • the DPF 15 collects particulate matter contained in the exhaust gas by depositing it on the partition walls of the honeycomb structure.
  • the deposited particulate matter is oxidized and purified by combustion. For this combustion, a temperature increase in the diesel oxidation catalyst 14 or a decrease in the combustion temperature of the particulate matter due to the additive is used.
  • the SCR catalytic converter 13 is a device for reducing NOx to nitrogen and water as a post-treatment device for the oxidation catalytic converter 12, and the SCR catalyst 16 carries a noble metal such as Pt on the surface of a base material such as zeolite or alumina.
  • the catalyst used is used.
  • the SCR catalyst 16 reduces and purifies NOx by adding urea as a reducing agent when the catalyst temperature is in the activation temperature range.
  • the exhaust pipe 11 there is a limit as a gas sensor on the upstream side of the oxidation catalytic converter 12, between the oxidation catalytic converter 12 and the SCR catalytic converter 13, upstream of the urea water addition valve 17, and downstream of the SCR catalytic converter 13.
  • Current-type NOx sensors 21, 22, and 23 are provided, respectively.
  • the NOx sensors 21 to 23 detect the NOx concentration in the exhaust gas at the respective detection positions.
  • the position and number of NOx sensors in the engine exhaust system may be arbitrary.
  • SCUs 31 to 33 are connected to the NOx sensors 21 to 23, and the detection signals of the NOx sensors 21 to 23 are appropriately output to the SCUs 31 to 33 for each sensor.
  • the SCUs 31 to 33 are electronic control devices including a CPU and a microcomputer having various memories and peripheral circuits thereof, and oxygen (O2) in exhaust gas based on detection signals (limit current signals) of the NOx sensors 21 to 23. The concentration and the NOx concentration as the concentration of the specific gas component are calculated.
  • the SCUs 31 to 33 are connected to a communication line 34 such as a CAN bus, and are connected to various ECUs (for example, an engine ECU 35) via the communication line 34. That is, the SCUs 31 to 33 and the engine ECU 35 can exchange information with each other using the communication line 34. For example, information on oxygen concentration and NOx concentration in exhaust gas is transmitted from the SCUs 31 to 33 to the engine ECU 35.
  • the engine ECU 35 is an electronic control device including a CPU, a microcomputer having various memories, and its peripheral circuits, and controls the engine 10 and various devices in the exhaust system.
  • the engine ECU 35 performs fuel injection control and the like based on, for example, the accelerator opening and the engine speed.
  • the engine ECU 35 performs urea water addition control by the urea water addition valve 17 based on the NOx concentration detected by each of the NOx sensors 21 to 23.
  • the engine ECU 35 calculates the urea water addition amount based on the NOx concentration detected by the NOx sensors 21 and 22 on the upstream side of the SCR catalytic converter 13, and the SCR catalytic converter 13.
  • the urea water addition amount is feedback-corrected so that the NOx concentration detected by the downstream NOx sensor 23 becomes as small as possible. Based on the urea water addition amount, the driving of the urea water addition valve 17 is controlled.
  • FIG. 2 and 3 are views showing the internal structure of the sensor element 40 constituting the NOx sensor 21.
  • FIG. 1 the left-right direction of a figure is a longitudinal direction of the sensor element 40, and the left side of a figure is an element front end side.
  • the sensor element 40 has a so-called three-cell structure including a pump cell 41, a sensor cell 42 and a monitor cell 43.
  • the monitor cell 43 has a function of discharging oxygen in the gas, like the pump cell 41, and may be referred to as an auxiliary pump cell or a second pump cell.
  • the sensor element 40 includes a first main body 51 and a second main body 52 made of an insulator such as alumina, a solid electrolyte body 53 disposed between the main bodies 51 and 52, a diffusion resistor 54, and a pump cell.
  • An electrode 55, a sensor cell electrode 56, a monitor cell electrode 57, a common electrode 58, and a heater 59 are provided.
  • a gas chamber 61 that is a concentration meter side chamber is formed between the first main body 51 and the solid electrolyte body 53, and an atmospheric chamber 62 that is a reference gas chamber is formed between the second main body 52 and the solid electrolyte body 53. Is formed.
  • the pump cell 41 adjusts the oxygen concentration in the exhaust gas introduced into the gas chamber 61, and is formed by the pump cell electrode 55, the common electrode 58, and a part of the solid electrolyte body 53.
  • the sensor cell 42 detects the concentration (NOx concentration) of a predetermined gas component in the gas chamber 61 based on an oxygen ion current flowing between the sensor cell electrode 56 and the common electrode 58.
  • the sensor cell electrode 56 and the common electrode 58 And a part of the solid electrolyte body 53.
  • the monitor cell 43 detects the residual oxygen concentration in the gas chamber 61 on the basis of the oxygen ion current flowing between the monitor cell electrode 57 and the common electrode 58, and one of the monitor cell electrode 57, the common electrode 58, and the solid electrolyte body 53. Part.
  • the solid electrolyte body 53 is a plate-like member and is made of an oxygen ion conductive solid electrolyte material such as zirconia oxide.
  • the first main body 51 and the second main body 52 are arranged on both sides of the solid electrolyte body 53.
  • the first main body 51 has a stepped shape on the solid electrolyte body 53 side, and a recess formed by the step is a gas chamber 61.
  • One side surface of the concave portion of the first main body 51 is open, and the diffusion resistor 54 is disposed on the open side surface.
  • the diffusion resistor 54 is made of a porous material or a material in which pores are formed. The speed of the exhaust gas introduced into the gas chamber 61 is regulated by the action of the diffusion resistor 54.
  • the second main body portion 52 has a stepped shape on the solid electrolyte body 53 side, and a concave portion formed by the step is an atmospheric chamber 62.
  • One side of the atmospheric chamber 62 is open. The gas introduced into the atmospheric chamber 62 from the solid electrolyte body 53 side is released to the atmosphere.
  • a pump cell electrode 55 On the surface facing the gas chamber 61 of the solid electrolyte body 53, a pump cell electrode 55, a sensor cell electrode 56, and a monitor cell electrode 57 on the cathode side are provided.
  • the pump cell electrode 55 is disposed on the inlet side of the gas chamber 61 close to the diffusion resistor 54, that is, on the upstream side in the gas chamber 61, and the sensor cell electrode 56 and the monitor cell electrode 57 have a diffusion resistance across the pump cell electrode 55. It is disposed on the opposite side of the body 54, that is, on the downstream side in the gas chamber 61.
  • the pump cell electrode 55 has a larger surface area than the sensor cell electrode 56 and the monitor cell electrode 57.
  • the sensor cell electrode 56 and the monitor cell electrode 57 are arranged side by side at positions close to each other and equivalent to the exhaust flow direction.
  • the pump cell electrode 55 and the monitor cell electrode 57 are electrodes made of a noble metal such as Au—Pt that is inactive to NOx (electrodes that are difficult to decompose NOx), whereas the sensor cell electrode 56 is platinum Pt and rhodium that are active to NOx. It is an electrode made of a noble metal such as Rh.
  • a common electrode 58 on the anode side is provided on the surface of the solid electrolyte body 53 facing the atmospheric chamber 62 at a position corresponding to each of the electrodes 55 to 57 on the cathode side.
  • a voltage applied to the pump cell 41 is a pump cell applied voltage Vp
  • a current output when the pump cell 41 is in a voltage applied state is a pump cell current Ip.
  • the monitor cell 43 detects the oxygen concentration remaining in the gas chamber 61 in a state where oxygen is exhausted by the pump cell 41. At this time, the monitor cell 43 outputs a current signal generated with voltage application or an electromotive force signal corresponding to the residual oxygen concentration in the gas chamber 61 as a residual oxygen concentration detection signal. The output of the monitor cell 43 is acquired by the SCUs 31 to 33 as the monitor cell current Im or the monitor cell electromotive force Vm.
  • the sensor cell 42 reduces and decomposes NOx in the exhaust gas according to voltage application in a state where oxygen is exhausted by the pump cell 41, and outputs a current signal corresponding to the NOx concentration and the residual oxygen concentration in the gas chamber 61.
  • the output of the sensor cell 42 is acquired as the sensor cell current Is in the SCUs 31 to 33.
  • the NOx concentration in the exhaust gas is calculated from the sensor cell current Is.
  • the NOx concentration in the exhaust gas is calculated by subtracting the monitor cell current Im from the sensor cell current Is.
  • the monitor cell 43 deteriorates, the accuracy of the monitor cell current Im decreases, and there is a concern that the NOx concentration detection may be affected. Therefore, in this embodiment, the deterioration determination is performed with the monitor cell 43 as a determination target.
  • Each of the SCUs 31 to 33 provided for each of the NOx sensors 21 to 23 has the same function.
  • FIG. 4 is a functional block diagram for explaining the functions of the SCUs 31 to 33 and the engine ECU 35.
  • the SCUs 31 to 33 adjust the residual oxygen concentration in the gas chamber 61 by the pump cell 41 and the residual oxygen concentration by the pump cell control unit M11 in order to control the monitor cell outputs (Vm, Im) to the target values.
  • an acquisition unit M12 that acquires the sensor cell output (Is) and a deterioration determination unit M13 that determines the deterioration state of the monitor cell 43 based on the sensor cell output acquired by the acquisition unit M12 are provided. Yes.
  • the NOx sensors 21 to 23 generate the monitor cell electromotive force Vm corresponding to the residual oxygen concentration in the gas chamber 61 as the monitor cell output, and the voltage applied to the monitor cell 43 in the gas chamber 61 It is possible to generate a monitor cell current Im corresponding to the residual oxygen concentration.
  • the monitor cell electromotive force Vm, the monitor cell current Im, the sensor cell current Is, the pump cell current Ip, and the like are appropriately detected.
  • the deterioration determination unit M13 performs the deterioration determination of the NOx sensors 21 to 23 with the monitor cell 43 or the monitor cell 43 and the sensor cell 42 as determination targets.
  • the pump cell control unit M11 causes the pump cell 41 to adjust the residual oxygen concentration by performing electromotive force feedback control (VmF / B control) for controlling the monitor cell electromotive force Vm to the target value Vmtg.
  • VmF / B control electromotive force feedback control
  • the pump cell control unit M11 sets the pump cell applied voltage Vp based on the deviation between the actual monitor cell electromotive force Vm and the target value Vmtg, and performs voltage application at the pump cell applied voltage Vp.
  • the pump cell control unit M11 causes the pump cell 41 to adjust the residual oxygen concentration by performing current feedback control (ImF / B control) for controlling the monitor cell current Im to the target value Imtg.
  • the pump cell control unit M11 sets the pump cell application voltage Vp based on the deviation between the actual monitor cell current Im and the target value Imtg, and performs voltage application to the pump cell 41 with the pump cell application voltage Vp.
  • the residual oxygen concentration is appropriately adjusted in the pump cell 41 by controlling the pump cell applied voltage Vp.
  • the electromotive force feedback control corresponds to “electromotive force control”
  • the current feedback control corresponds to “monitor cell current control”.
  • the acquisition unit M12 acquires the sensor cell current Is that changes in response by the electromotive force feedback control as the sensor cell output in a state where the residual oxygen concentration is adjusted by the electromotive force feedback control. In addition, as the sensor cell output in a state where the residual oxygen concentration is adjusted by the current feedback control, the sensor cell current Is that changes in response by the current feedback control is acquired.
  • the degradation determination unit M13 determines degradation of the monitor cell 43 and the sensor cell 42 using at least one of the sensor cell current Is acquired when the electromotive force feedback control is performed and the sensor cell current Is acquired when the current feedback control is performed. To implement. For example, the deterioration determination unit M13 calculates the deterioration rate Cm of the monitor cell 43 based on the response change amount ⁇ Is of the sensor cell current Is, while calculating the deterioration rate Cs of the sensor cell 42 based on the response change amount ⁇ Is of the sensor cell current Is. To do.
  • the engine ECU 35 has an abnormality determination unit M21 that determines abnormality due to emission deterioration based on the deterioration determination results of the SCUs 31 to 33.
  • the abnormality determination unit M21 determines an abnormality in engine emission based on the deterioration rate Cm of the monitor cell 43 and the deterioration rate Cs of the sensor cell 42 calculated by the deterioration determination unit M13 of each of the SCUs 31 to 33.
  • the emission abnormality is determined by comprehensively considering the outputs of the NOx sensors 21 to 23, various sensor information from other sensors, the engine operating state, and the like. May be.
  • Both the deterioration determination and the emission abnormality determination regarding the NOx sensors 21 to 23 may be performed by the SCUs 31 to 33, or both may be performed by the engine ECU 35. Since it is desirable that the emission abnormality determination is performed using elements other than the degree of deterioration of the NOx sensors 21 to 23, it is preferable that the emission abnormality determination is performed by the engine ECU 35.
  • the SCUs 31 to 33 perform electromotive force feedback control so that the monitor cell electromotive force Vm generated according to the residual oxygen concentration in the gas chamber 61 matches the target value Vmtg.
  • the target value Vmtg is within a sudden change region where the monitor cell electromotive force Vm changes suddenly in the electromotive force characteristics of the monitor cell 43, and the oxygen concentration is larger than 0 (ie, excess air).
  • the rate may be determined as monitor cell electromotive force Vm.
  • the residual oxygen concentration is controlled to 1000 ppm, for example (A1 in the figure).
  • the electromotive force characteristic changes as the sensitivity decreases, as shown by the solid line in FIG.
  • the initial characteristic before deterioration is indicated by a one-dot chain line
  • the characteristic after deterioration is indicated by a solid line.
  • the monitor cell electromotive force Vm is small. Therefore, the actual residual oxygen concentration in the gas chamber 61 deviates from the target oxygen concentration under the state where the electromotive force feedback control is performed. Specifically, as shown in FIG. 5C in which the portion X in FIG. 5B is enlarged, the residual oxygen concentration decreases from A1 to A2 when the electromotive force feedback control is performed.
  • the SCUs 31 to 33 determine the deterioration of the monitor cell 43 by utilizing the change in the responsiveness of the sensor cell current Is according to the change in the residual oxygen concentration accompanying the deterioration of the monitor cell 43 during the electromotive force feedback control. To implement. The outline will be described with reference to the time chart of FIG.
  • electromotive force feedback control is started at time t1.
  • the residual oxygen concentration in the gas chamber 61 is extremely low before time t1, and oxygen supply to the monitor cell 43 and the sensor cell 42 is started with the start of the electromotive force feedback control. That is, in the electromotive force feedback control, the oxygen concentration is adjusted so that the residual oxygen concentration increases.
  • the sensor cell current Is changes transiently as indicated by the alternate long and short dash line, whereas when the deterioration of the monitor cell 43 occurs, the residual oxygen concentration becomes lower than expected. As a result, the sensor cell current Is changes transiently as indicated by a solid line.
  • the response change amount ⁇ Is1 of the sensor cell current Is decreases with respect to the initial value of the response change amount of the sensor cell current Is calculated in advance under the same conditions as the current electromotive force feedback control (hereinafter referred to as the initial change amount ⁇ Isini1). Due to the difference in the change in the sensor cell current Is, the deterioration of the monitor cell 43 can be determined.
  • FIG. 7 is a flowchart showing a processing procedure for determining the deterioration of the NOx sensors 21 to 23 when the electromotive force feedback control (VmF / B control) is performed.
  • the processing shown in FIG. 7 is arithmetic processing for realizing the functions of the SCUs 31 to 33 shown in FIG. 4, and is executed in each of the SCUs 31 to 33, for example, at predetermined intervals.
  • step S11 it is determined whether or not an execution condition for deterioration determination is satisfied.
  • the implementation condition includes, for example, receiving an permission signal from the engine ECU 35 to permit the execution of the deterioration determination.
  • the engine ECU 35 transmits a permission signal when the gas environment in the exhaust pipe 11 is in a predetermined environment that is stable. Specifically, the engine ECU 35 is in a state where the engine 10 is in a predetermined operation state and the amount of exhaust is relatively stable, in the case of fuel cut, immediately after the ignition switch is turned off (immediately after the IG is turned off), Alternatively, the permission signal is transmitted when the engine ECU 35 is being activated by the soak timer. In particular, it is desirable that the condition is immediately after the IG is turned off.
  • step S12 electromotive force feedback control is performed.
  • the target value Vmtg of the monitor cell electromotive force Vm is set, and the pump cell applied voltage Vp is feedback-controlled based on the deviation between the target value Vmtg and the actual monitor cell electromotive force Vm.
  • the monitor cell electromotive force Vm is controlled to the target value Vmtg, and the residual oxygen concentration in the gas chamber 61 is adjusted to an oxygen concentration corresponding to the target value Vmtg.
  • a response change amount ⁇ Is1 of the sensor cell current Is is calculated after the start of the electromotive force feedback control.
  • the response change amount ⁇ Is1 is calculated from the difference from the sensor cell current Is before the start.
  • step S14 using the following equation (1), the output ratio ⁇ 1 is calculated from the response change amount ⁇ Is1 and the initial change amount ⁇ Isini1 of the sensor cell current Is calculated this time.
  • the output ratio ⁇ 1 is calculated as a ratio of the response change amount ⁇ Is1 to the initial change amount ⁇ Isini1.
  • the initial change amount ⁇ Isini1 is stored in advance in the memories in the SCUs 31 to 33.
  • ⁇ 1 ⁇ Is1 / ⁇ Isini1 (1)
  • step S15 it is determined whether or not the output ratio ⁇ 1 is smaller than a predetermined value TH1. Note that 0 ⁇ TH1 ⁇ 1. And if step S15 is YES, it will consider that the monitor cell 43 has deteriorated and will progress to step S16.
  • step S15 is to determine whether or not the output ratio ⁇ 1 calculated this time has occurred due to deterioration of the monitor cell 43. That is, comparing the case where the response change amount ⁇ Is1 of the sensor cell current Is decreases with the deterioration of the monitor cell 43 and the case where the response change amount ⁇ Is1 of the sensor cell current Is decreases with the deterioration of the sensor cell 42, the former is more responsive. There is a tendency that the degree of decrease of the change amount ⁇ Is1 increases ( ⁇ Is1 tends to be a small value). This is because when the monitor cell 43 is deteriorated, a current drop occurs due to a shift in the residual oxygen concentration. From this difference, it is possible to specify that the cause of deterioration is the monitor cell 43.
  • step S16 for example, the deterioration rate Cm of the monitor cell 43 is calculated based on the output ratio ⁇ 1 using the relationship L1 in FIG. According to the relationship L1, the deterioration rate Cm is calculated as a larger value as the output ratio ⁇ 1 is smaller than 1, that is, as the difference from the initial characteristic is larger.
  • a large deterioration rate Cm means that the degree of deterioration of the monitor cell 43 is large.
  • the step S15 can be omitted.
  • the monitor cell 43 has the current characteristics shown in FIG. 9 as the relationship between the oxygen concentration and the monitor cell current Im.
  • the SCUs 31 to 33 perform current feedback control so that the monitor cell current Im generated according to the residual oxygen concentration in the gas chamber 61 matches the target value Immtg.
  • the initial characteristics before deterioration are indicated by a one-dot chain line, and the characteristics after deterioration are indicated by solid lines.
  • the reaction sensitivity to oxygen is reduced as the characteristics change. Therefore, the actual residual oxygen concentration in the gas chamber 61 deviates from the target oxygen concentration under the state where the current feedback control is performed. Specifically, as shown in FIG. 9, the residual oxygen concentration increases from A3 to A4 when the current feedback control is performed.
  • the SCUs 31 to 33 determine the deterioration of the monitor cell 43 using the change in the response of the sensor cell current Is accordingly. To implement. The outline will be described with reference to the time chart of FIG.
  • current feedback control is started at time t2.
  • the residual oxygen concentration in the gas chamber 61 is extremely low, and oxygen supply to the monitor cell 43 and the sensor cell 42 is started with the start of the current feedback control. That is, in the current feedback control, the oxygen concentration is adjusted so that the residual oxygen concentration increases.
  • the sensor cell current Is changes transiently as indicated by the alternate long and short dash line, whereas when the deterioration of the monitor cell 43 occurs, the residual oxygen concentration becomes higher than expected. As a result, the sensor cell current Is changes transiently as indicated by a solid line.
  • the response change amount ⁇ Is2 of the sensor cell current Is increases with respect to the initial value of the response change amount of the sensor cell current Is calculated in advance under the same conditions as the current feedback control (hereinafter referred to as the initial change amount ⁇ Isini2). Due to the difference in the change in the sensor cell current Is, the deterioration of the monitor cell 43 can be determined.
  • FIG. 11 is a flowchart showing a processing procedure for determining the deterioration of the NOx sensors 21 to 23 when the current feedback control (ImF / B control) is performed.
  • the process shown in FIG. 11 is an arithmetic process for realizing each function of the SCUs 31 to 33 shown in FIG. 4, and is executed in each SCU 31 to 33, for example, at predetermined intervals.
  • step S21 it is determined whether or not an execution condition for deterioration determination is satisfied. However, since this process is the same as step S11 of FIG. 7, detailed description thereof is omitted. If the execution condition for the deterioration determination is satisfied, the process proceeds to the subsequent step S22. If the execution condition is not satisfied, the present process is terminated.
  • step S22 current feedback control is performed.
  • the target value Imtg of the monitor cell current Im is set, and the pump cell applied voltage Vp is feedback-controlled based on the deviation between the target value Imtg and the actual monitor cell current Im.
  • the monitor cell current Im is controlled to the target value Imtg, and the residual oxygen concentration in the gas chamber 61 is adjusted to an oxygen concentration corresponding to the target value Immtg.
  • step S23 the response change amount ⁇ Is2 of the sensor cell current Is is calculated after the start of the current feedback control.
  • the response change amount ⁇ Is2 is calculated based on the difference from the previous sensor cell current Is.
  • step S25 it is determined whether or not the difference ⁇ 1 is smaller than the negative predetermined value TH2.
  • step S26 it is determined whether or not the difference ⁇ 1 is larger than the positive predetermined value TH3.
  • the initial change amount ⁇ Isini2 is stored in advance in the memories in the SCUs 31 to 33. TH2 ⁇ 0 and TH3> 0.
  • the processing of steps S24 to S26 is to determine whether the difference ⁇ 1 between the response change amount ⁇ Is2 calculated this time and the initial change amount ⁇ Isini2 is caused by the deterioration of the monitor cell 43 or the sensor cell 42. .
  • the processing of steps S24 to S26 is to determine whether the difference ⁇ 1 between the response change amount ⁇ Is2 calculated this time and the initial change amount ⁇ Isini2 is caused by the deterioration of the monitor cell 43 or the sensor cell 42. .
  • the residual oxygen concentration is shifted to a larger side (see FIG. 9), but the sensor cell 42, not the monitor cell 43, is deteriorated. In this state, the residual oxygen concentration is adjusted to an appropriate value.
  • the response change amount ⁇ Is2 of the sensor cell current Is is larger than the initial change amount ⁇ Isini2
  • the response change amount ⁇ Is2 of the sensor cell current Is becomes smaller than the initial change amount ⁇ Isini2. Therefore, it is possible to determine whether the deterioration of the monitor cell 43 or the deterioration of the sensor cell 42 occurs depending on whether the response change amount ⁇ Is2 of the sensor cell current Is increases or decreases with respect to the initial change amount ⁇ Isini2. It has become.
  • step S25 is YES
  • the monitor cell 43 is regarded as degraded and the process proceeds to step S27.
  • step S26 is YES, the sensor cell 42 is regarded as degraded and the process proceeds to step S28.
  • step S27 the deterioration determination of the monitor cell 43 is performed based on the response change amount ⁇ Is2 of the sensor cell current Is.
  • the output ratio ⁇ 2 is calculated from the response change amount ⁇ Is2 and the initial change amount ⁇ Isini2 of the sensor cell current Is calculated this time.
  • ⁇ 2 ⁇ Is2 / ⁇ Isini2 (2)
  • the deterioration rate Cm of the monitor cell 43 is calculated based on the output ratio ⁇ 2.
  • the deterioration rate Cm is calculated as a larger value as the output ratio ⁇ 2 is larger than 1, that is, as the difference from the initial characteristic is larger.
  • step S28 the deterioration of the sensor cell 42 is determined based on the response change amount ⁇ Is2 of the sensor cell current Is.
  • the output ratio ⁇ 3 is calculated from the response change amount ⁇ Is2 and the initial change amount ⁇ Isini2 of the sensor cell current Is calculated this time.
  • ⁇ 3 ⁇ Is2 / ⁇ Isini2 (3)
  • the deterioration rate Cs of the sensor cell 42 is calculated based on the output ratio ⁇ 3 using the relationship L3 in FIG. 8B. According to the relationship L3, the deterioration rate Cs is calculated as a larger value as the output ratio ⁇ 3 is smaller than 1, that is, as the difference from the initial characteristic is larger.
  • the output ratio ⁇ 2 is calculated prior to steps S27 and S28, and whether the output ratio ⁇ 2 is greater than a predetermined value TH4 or the output ratio ⁇ 2
  • the output ratio ⁇ 2 is smaller than the predetermined value TH5, it is determined that the sensor cell 42 is deteriorated. Then, based on each determination result, it progresses to Step S27 and Step S28.
  • Degradation determination process when the SCUs 31 to 33 perform electromotive force feedback control (VmF / B control) (FIG. 7) and deterioration determination process when current feedback control (ImF / B control) is performed (FIG. 11) The structure which implements only any one of these may be sufficient.
  • each of these determination processes may be performed at different execution opportunities. For example, one of the determination processes may be performed for each drive cycle, one determination process may be performed immediately after the current IG is turned off, and the other determination process may be performed immediately after the next IG is turned off.
  • FIG. 12 shows the relationship between the response change of the sensor cell current Is when the monitor cell deteriorates and the response change of the sensor cell current Is when the sensor cell deteriorates when the electromotive force feedback control and the current feedback control are executed. Are shown together.
  • the initial characteristics are indicated by a one-dot chain line, and the deteriorated characteristics are indicated by a solid line.
  • the response change amount ⁇ Is1 of the sensor cell current Is decreases when the electromotive force feedback control is performed, and the response change amount ⁇ Is2 of the sensor cell current Is increases when the current feedback control is performed.
  • the response change amount ⁇ Is1 of the sensor cell current Is decreases when the electromotive force feedback control is performed, and the response change amount ⁇ Is2 of the sensor cell current Is decreases when the current feedback control is performed.
  • the SCUs 31 to 33 have a response change amount ⁇ Is1 when the electromotive force feedback control is performed smaller than the initial change amount ⁇ Isini1 that is the first reference value, and the current Based on the fact that the response change amount ⁇ Is2 when the feedback control is performed becomes larger than the initial change amount ⁇ Isini2 that is the second reference value, it is determined that the monitor cell 43 is deteriorated. Further, the response change amount ⁇ Is1 when the electromotive force feedback control is performed is smaller than the initial change amount ⁇ Isini1, and the response change amount ⁇ Is2 when the current feedback control is performed is smaller than the initial change amount ⁇ Isini2. Based on the above, it is determined that the sensor cell 42 has deteriorated.
  • FIG. 13 is a flowchart showing a processing procedure for determining the deterioration of the NOx sensors 21 to 23 when performing electromotive force feedback control (VmF / B control) and current feedback control (ImF / B control).
  • the process shown in FIG. 13 is an arithmetic process for realizing each function of the SCUs 31 to 33 shown in FIG. 4, and is executed in each SCU 31 to 33, for example, at predetermined intervals.
  • the processing in FIG. 13 is performed instead of the processing in FIG. 7 and FIG.
  • step S31 it is determined whether or not an execution condition for deterioration determination is satisfied. However, since this process is the same as step S11 of FIG. 7, detailed description thereof is omitted. If the execution condition for the deterioration determination is satisfied, the process proceeds to the subsequent step S32. If the execution condition is not satisfied, the present process is terminated.
  • steps S32 and S33 electromotive force feedback control is performed, and the response change amount ⁇ Is1 of the sensor cell current Is is calculated (same as steps S12 and S13 described above).
  • steps S34 and S35 current feedback control is performed, and the response change amount ⁇ Is2 of the sensor cell current Is is calculated (same as steps S22 and S23 described above).
  • step S36 it is determined whether or not the response change amount ⁇ Is1 has decreased with respect to the initial change amount ⁇ Isini1, and in step S37, whether or not the response change amount ⁇ Is2 has increased with respect to the initial change amount ⁇ Isini2. Determine. And when both step S36 and S37 are YES, it progresses to step S38 and the deterioration determination of the monitor cell 43 is implemented. Moreover, when step S36 is YES and step S37 is NO, it progresses to step S39 and the deterioration determination of the sensor cell 42 is implemented.
  • the calculation process of the response change amount ⁇ Is1 in steps S32 and S33 and the calculation process of the response change amount ⁇ Is2 in steps S34 and S35 can be performed discontinuously, that is, at different execution opportunities.
  • the processing may be performed for each drive cycle, the response change amount ⁇ Is1 may be calculated immediately after the current IG is turned off, and the response change amount ⁇ Is2 may be calculated immediately after the next IG is turned off. Then, when the response change amounts ⁇ Is1 and ⁇ Is2 are calculated, the deterioration determination of either the monitor cell 43 or the sensor cell 42 is performed.
  • the monitor cell 43 in order to control the monitor cell output (Vm, Im) to the target value, the residual oxygen concentration is adjusted by the pump cell 41, and based on the sensor cell output acquired in the state where the residual oxygen concentration is adjusted, the monitor cell 43 deterioration states were determined.
  • the monitor cell 43 if the monitor cell 43 is deteriorated, the residual oxygen concentration in the gas chamber 61 becomes excessive or low in a state where the monitor cell output is controlled to the target value, and the sensor cell output fluctuates due to the influence thereof.
  • the deterioration state of the monitor cell 43 can be determined using As a result, the deterioration state of the monitor cell 43 can be properly determined in the NOx sensors 21 to 23 having the pump cell 41, the sensor cell 42, and the monitor cell 43.
  • the monitor cell output (Vm, Im) is controlled to the target value
  • the residual oxygen concentration in the gas chamber 61 is kept constant, so that the deterioration determination of the monitor cell 43 can be performed under a condition where the oxygen concentration is constant. For this reason, it is possible to increase the degradation determination accuracy.
  • the electromotive force feedback control for adjusting the monitor cell electromotive force Vm to the target value is performed to adjust the residual oxygen concentration by the pump cell 41 (FIG. 7).
  • the actual residual oxygen concentration in the gas chamber 61 is the target oxygen in the state where the electromotive force feedback control is performed due to the change in the electromotive force characteristic due to the sensitivity decrease. Deviation from concentration.
  • the response change amount ⁇ Is1 of the sensor cell current Is deviates from a predetermined reference value (initial change amount ⁇ Isini1), it can be appropriately determined that the monitor cell 43 has deteriorated.
  • the residual oxygen concentration is shifted to a smaller side by performing the electromotive force feedback control.
  • the response change amount ⁇ Is1 of the sensor cell current Is becomes smaller than a predetermined reference value (initial change amount ⁇ Isini1). Based on this, the deterioration state of the monitor cell 43 is appropriately set. Can be determined.
  • the response change amount ⁇ Is1 of the sensor cell current Is According to the deviation of the residual oxygen concentration.
  • the response change amount ⁇ Is1 of the sensor cell current Is similarly decreases.
  • the former is more responsive.
  • the monitor cell 43 has deteriorated among the monitor cell 43 and the sensor cell 42 based on being smaller than the value, that is, the degree of decrease in the response change amount ⁇ Is1 with respect to the initial change amount ⁇ Isini1 is large. Can do.
  • the residual oxygen concentration is shifted to the side by increasing the current feedback control.
  • the response change amount ⁇ Is2 of the sensor cell current Is becomes larger than a predetermined reference value (initial change amount ⁇ Isini2). Based on this, the deterioration state of the monitor cell 43 is appropriately set. Can be determined.
  • the residual oxygen concentration is adjusted to an appropriate value if the monitor cell 43 is in a normal state rather than a deteriorated state.
  • the response change amount ⁇ Is2 of the sensor cell current Is is smaller than a predetermined reference value (initial change amount ⁇ Isini2) due to a decrease in response due to the deterioration. . Therefore, the deterioration state of the sensor cell 42 can be appropriately determined based on the decrease in the response change amount ⁇ Is.
  • the electromotive force feedback control of the monitor cell 43 is performed to calculate the response change amount ⁇ Is1 of the sensor cell current Is at that time, while the current feedback control is performed to calculate the response change amount ⁇ Is2 of the sensor cell current Is at that time.
  • the monitor cell 43 and the sensor cell 42 are subjected to deterioration determination (FIG. 13).
  • the deterioration of the NOx sensors 21 to 23 is mainly caused by the deterioration of the monitor cell 43 or the deterioration of the sensor cell 42. Since the mode of the response change of the sensor cell current Is changes depending on whether or not the sensor cell 43 or the sensor cell 42 is deteriorated, it can be suitably determined.
  • the characteristic change of the sensor cell current Is when the electromotive force feedback control and the current feedback control are performed differs between the state in which the monitor cell 43 is deteriorated and the state in which the sensor cell 42 is deteriorated as shown in FIG. Therefore, it is distinguished whether the deterioration of the NOx sensors 21 to 23 is the deterioration of the monitor cell 43 or the sensor cell 42. As a result, the NOx sensors 21 to 23 can appropriately determine the deterioration state of the monitor cell 43 and the deterioration state of the sensor cell 42, respectively.
  • Vm is set as a target value, and the oxygen concentration is adjusted by the pump cell 41 based on the target value.
  • the NOx sensors 21 to 23 have a one-chamber structure in which each electrode (cathode) of the pump cell 41, the sensor cell 42, and the monitor cell 43 is provided in the same gas chamber 61.
  • the gas atmosphere of the monitor cell 43 and the sensor cell 42 can be switched at an early stage by adjusting the oxygen concentration of the pump cell applied voltage Vp, so that deterioration can be determined in a shorter time compared to a configuration having a plurality of chambers. .
  • the slope of the sensor cell current Is during a transient change instead of the response change amount ⁇ Is of the sensor cell current Is as a parameter for determining deterioration.
  • the SCUs 31 to 33 have a function of switching the pump cell applied voltage Vp to a predetermined value and determining the deterioration state of the sensor cell 42 based on a change in the sensor cell current Is accompanying the voltage switching.
  • the SCUs 31 to 33 (degradation determination unit M13) determine the deterioration state of the monitor cell 43 based on the response change amount ⁇ Is of the sensor cell current Is in the state where the electromotive force feedback control is performed and the deterioration determination result of the sensor cell 42. judge.
  • the deterioration determination of the sensor cell 42 performed by switching the pump cell applied voltage Vp will be briefly described with reference to FIG.
  • the pump cell applied voltage Vp is switched from Vp0 to Vp1 stepwise (Vp0> Vp1).
  • the pump cell current Ip is changed to a decreasing side, and the residual oxygen concentration in the gas chamber 61 is increased.
  • the sensor cell current Is increases to a steady value (convergence value) through a transient response as the residual oxygen concentration increases.
  • the SCUs 31 to 33 perform the deterioration determination of the sensor cell 42.
  • FIG. 15 is a flowchart showing the deterioration determination process in the present embodiment. This process is performed by the SCUs 31 to 33, for example, at a predetermined cycle.
  • step S31 it is determined whether or not an execution condition for deterioration determination is satisfied. However, since this process is the same as step S11 of FIG. 7, detailed description thereof is omitted. If the execution condition for the deterioration determination is satisfied, the process proceeds to the subsequent step S42. If the execution condition is not satisfied, the present process is terminated.
  • step S42 the pump cell applied voltage Vp is switched from Vp0 to Vp1.
  • Vp1 is a predetermined value.
  • step S43 an output change amount of the sensor cell current Is after voltage switching is calculated.
  • the response change amount ⁇ Is3 (see FIG. 14) is calculated from the sensor cell current Is after the current change converges.
  • the output change amount of the sensor cell current Is it is also possible to calculate the slope at the time of the transient change of the sensor cell current Is.
  • step S44 the response change amount ⁇ Is3 is compared with the initial value of the response change amount of the sensor cell current Is calculated in advance under the same conditions as the current voltage switching (hereinafter, referred to as the initial change amount ⁇ Isini3). Deterioration judgment is performed.
  • the deterioration determination may be performed by calculating the output ratio ( ⁇ Is3 / ⁇ Isini3) based on the ratio between the response change amount ⁇ Is3 and the initial change amount ⁇ Isini3 and calculating the deterioration rate based on the output ratio.
  • steps S45 and S46 electromotive force feedback control is performed to calculate the response change amount ⁇ Is1 of the sensor cell current Is (same as steps S12 and S13 described above).
  • step S47 the deterioration of the monitor cell 43 is determined.
  • the deterioration rate Cm of the monitor cell 43 is calculated based on the response change amount ⁇ Is1 and the initial change amount ⁇ Isini1 of the sensor cell current Is while taking into consideration the determination result in step S44 (the deterioration state of the sensor cell 42).
  • the deterioration rate Cm of the monitor cell 43 is calculated on the condition that no deterioration has occurred in the sensor cell 42 (the deterioration rate of the sensor cell 42 is less than a predetermined value). In this case, if the sensor cell 42 is in a deteriorated state, the deterioration determination of the monitor cell 43 is not performed.
  • the deterioration rate Cm of the monitor cell 43 is corrected based on the deterioration rate (degradation degree) of the sensor cell 42.
  • the response change amount ⁇ Is of the sensor cell current Is tends to decrease both when the monitor cell 43 is deteriorated and when the sensor cell 42 is deteriorated.
  • the deterioration rate Cm of the monitor cell 43 is corrected to the decreasing side. That is, the correction is made to reduce the degree of deterioration.
  • step S45 and S46 current feedback control can be performed instead of the electromotive force feedback control, and the response change amount ⁇ Is2 of the sensor cell current Is can be calculated (same as the above-described steps S22 and S23).
  • step S47 the deterioration rate Cm of the monitor cell 43 is calculated based on the response change amount ⁇ Is2 and the initial change amount ⁇ Isini2 of the sensor cell current Is while taking the determination result in step S44 (deterioration state of the sensor cell 42) into account. calculate.
  • the specific contents are the same as described above.
  • the deterioration of the monitor cell 43 is determined based on the deterioration rate of the sensor cell 42.
  • the rate Cm may be corrected to the increasing side. That is, the correction is made so that the degree of deterioration becomes larger.
  • the sensor cell current Is changes with a change in the residual oxygen concentration due to the voltage switching, and the deterioration state of the sensor cell 42 can be determined based on the change in the sensor cell current Is.
  • the deterioration state of the monitor cell 43 is determined based on the sensor cell current Is acquired with the execution of the electromotive force feedback control while taking into account the deterioration determination result of the sensor cell 42.
  • the transient change of the sensor cell current Is depends on the deterioration state of both the monitor cell 43 and the sensor cell 42, but it is possible to appropriately determine the deterioration state of the monitor cell 43 by performing the deterioration determination individually. Become.
  • the initial value calculated in advance under the same conditions is used as the reference value used when performing the deterioration determination of the monitor cell 43 or the deterioration determination of the sensor cell 42, but the degree of deterioration over time can be grasped. Any other value may be used.
  • a predetermined value other than the initial value a predetermined value determined according to the number of years of use, or the like can be used.
  • the sensor element 40 has a single solid electrolyte body 53 and a single gas chamber 61 (one-chamber structure), but this may be changed.
  • the sensor element 40 has a plurality of solid electrolyte bodies 53 and a plurality of gas chambers 61, and the pump cell 41 and the sensor cell 42 are different solid electrolyte bodies 53 and face the other gas chambers 61.
  • the structure provided so that it may be sufficient. An example of such a configuration is shown in FIG.
  • the sensor element 40 shown in FIG. 16 has two solid electrolyte bodies 53a and 53b arranged opposite to each other, and gas chambers 61a and 61b provided between the solid electrolyte bodies 53a and 53b.
  • the gas chamber 61a communicates with the exhaust introduction port 53c
  • the gas chamber 61b communicates with the gas chamber 61a via the throttle portion 71.
  • the pump cell 41 has a pair of electrodes 72 and 73, and one of the electrodes 72 is provided so as to be exposed in the gas chamber 61a.
  • the sensor cell 42 has an electrode 74 and a common electrode 76 that are arranged to face each other, and the monitor cell 43 has an electrode 75 and a common electrode 76 that are arranged to face each other.
  • the sensor cell 42 and the monitor cell 43 are provided adjacent to each other.
  • one electrode 74, 75 is provided so as to be exposed in the gas chamber 61b.
  • the specific gas component to be detected may be other than NOx.
  • it may be a gas sensor that detects HC or CO in the exhaust.
  • oxygen in exhaust gas is discharged by the pump cell, and HC and CO are decomposed from the gas after oxygen discharge by the sensor cell to detect the HC concentration and CO concentration.
  • concentration of ammonia in the gas to be detected may be detected.
  • the gas sensor may use a gas other than exhaust as a gas to be detected, or may be used for applications other than automobiles.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Electrochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Molecular Biology (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

L'invention concerne un capteur de gaz qui comprend : une cellule de pompe qui, au moyen de l'application d'une tension, ajuste la concentration d'oxygène dans un gaz détecté qui a été introduit dans une chambre à gaz; une cellule de capteur qui détecte la concentration d'un composant gazeux spécifique dans la chambre à gaz après que la concentration d'oxygène ait été ajustée par la cellule de pompe; et une cellule de surveillance qui détecte la concentration d'oxygène résiduelle dans la chambre à gaz. Chaque SCU 31-33 comprend : une unité de commande de cellule de pompe (M11) qui amène la cellule de pompe à ajuster la concentration d'oxygène résiduel de manière à régler la sortie de la cellule de surveillance à une valeur cible; une unité d'acquisition (M12) qui acquiert une sortie de la cellule de capteur, dans un état dans lequel la concentration d'oxygène résiduelle a été ajustée par l'unité de commande de cellule de pompe; et une unité de détermination de dégradation (M13) qui détermine l'état de dégradation de la cellule de surveillance sur la base de la sortie de la cellule de capteur, acquise par l'unité d'acquisition.
PCT/JP2018/020595 2017-05-30 2018-05-29 Dispositif de commande de capteur de gaz WO2018221528A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE112018002768.6T DE112018002768T5 (de) 2017-05-30 2018-05-29 Gassensor-steuervorrichtung

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2017-107026 2017-05-30
JP2017107026A JP6638700B2 (ja) 2017-05-30 2017-05-30 ガスセンサ制御装置

Publications (1)

Publication Number Publication Date
WO2018221528A1 true WO2018221528A1 (fr) 2018-12-06

Family

ID=64454800

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2018/020595 WO2018221528A1 (fr) 2017-05-30 2018-05-29 Dispositif de commande de capteur de gaz

Country Status (3)

Country Link
JP (1) JP6638700B2 (fr)
DE (1) DE112018002768T5 (fr)
WO (1) WO2018221528A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019086396A (ja) 2017-11-07 2019-06-06 株式会社デンソー 制御装置
JP2023070336A (ja) * 2021-11-09 2023-05-19 株式会社デンソー 制御装置

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003254939A (ja) * 2001-12-27 2003-09-10 Nippon Soken Inc ガス濃度検出装置
JP2004333374A (ja) * 2003-05-09 2004-11-25 Nippon Soken Inc ガス濃度センサの異常検出装置
JP2007147383A (ja) * 2005-11-25 2007-06-14 Ngk Spark Plug Co Ltd センサ素子劣化判定装置およびセンサ素子劣化判定方法
JP2007147386A (ja) * 2005-11-25 2007-06-14 Ngk Spark Plug Co Ltd センサ素子劣化判定装置およびセンサ素子劣化判定方法
JP2009175013A (ja) * 2008-01-24 2009-08-06 Toyota Motor Corp ＮＯｘセンサの劣化診断装置
JP2015059926A (ja) * 2013-09-20 2015-03-30 株式会社デンソー ガスセンサ制御装置
JP2015105843A (ja) * 2013-11-29 2015-06-08 株式会社デンソー ガスセンサ制御装置
WO2016013229A1 (fr) * 2014-07-25 2016-01-28 株式会社デンソー Dispositif de détection de concentration gazeuse

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003254939A (ja) * 2001-12-27 2003-09-10 Nippon Soken Inc ガス濃度検出装置
JP2004333374A (ja) * 2003-05-09 2004-11-25 Nippon Soken Inc ガス濃度センサの異常検出装置
JP2007147383A (ja) * 2005-11-25 2007-06-14 Ngk Spark Plug Co Ltd センサ素子劣化判定装置およびセンサ素子劣化判定方法
JP2007147386A (ja) * 2005-11-25 2007-06-14 Ngk Spark Plug Co Ltd センサ素子劣化判定装置およびセンサ素子劣化判定方法
JP2009175013A (ja) * 2008-01-24 2009-08-06 Toyota Motor Corp ＮＯｘセンサの劣化診断装置
JP2015059926A (ja) * 2013-09-20 2015-03-30 株式会社デンソー ガスセンサ制御装置
JP2015105843A (ja) * 2013-11-29 2015-06-08 株式会社デンソー ガスセンサ制御装置
WO2016013229A1 (fr) * 2014-07-25 2016-01-28 株式会社デンソー Dispositif de détection de concentration gazeuse

Also Published As

Publication number Publication date
DE112018002768T5 (de) 2020-02-20
JP6638700B2 (ja) 2020-01-29
JP2018204985A (ja) 2018-12-27

Similar Documents

Publication Publication Date Title
US11249043B2 (en) Control device for gas sensor
WO2016013229A1 (fr) Dispositif de détection de concentration gazeuse
US9739225B2 (en) Control system of internal combustion engine
US11428663B2 (en) Gas sensor control device
JP2009175013A (ja) ＮＯｘセンサの劣化診断装置
US11054388B2 (en) Gas sensor control device
WO2018221528A1 (fr) Dispositif de commande de capteur de gaz
JP6344262B2 (ja) 排気センサ
JP6255948B2 (ja) ガスセンサ制御装置
WO2018216808A1 (fr) Dispositif de commande de capteur de gaz
JP2009175014A (ja) ＮＯｘセンサ及びその劣化診断装置
WO2016121380A1 (fr) Dispositif de commande de moteur à combustion interne
JP6819538B2 (ja) ガスセンサ制御装置
JP2017067717A (ja) ガスセンサ制御装置、基準点学習方法、基準点診断方法
US11174807B2 (en) Operation control method of vehicle engine and vehicle system
US11092099B2 (en) Control apparatus
US11035283B2 (en) Control apparatus
US20190219537A1 (en) Control device
JP2020180990A (ja) ガスセンサの制御装置
JP2018059941A (ja) ガスセンサ制御装置
JP2017116309A (ja) 内燃機関のガス濃度検出装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18809572

Country of ref document: EP

Kind code of ref document: A1

122 Ep: pct application non-entry in european phase

Ref document number: 18809572

Country of ref document: EP

Kind code of ref document: A1