CN113464292A - Deterioration determination device for air-fuel ratio sensor - Google Patents
Deterioration determination device for air-fuel ratio sensor Download PDFInfo
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- CN113464292A CN113464292A CN202110330792.9A CN202110330792A CN113464292A CN 113464292 A CN113464292 A CN 113464292A CN 202110330792 A CN202110330792 A CN 202110330792A CN 113464292 A CN113464292 A CN 113464292A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/22—Safety or indicating devices for abnormal conditions
- F02D41/222—Safety or indicating devices for abnormal conditions relating to the failure of sensors or parameter detection devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/1446—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being exhaust temperatures
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/021—Engine temperature
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- 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
Abstract
The invention provides a deterioration determination device for an air-fuel ratio sensor, which can avoid the false determination caused by the temporary reduction of the responsiveness caused by the accumulation of dust and can determine the response deterioration of the air-fuel ratio sensor with high precision. The deterioration determination device of the present invention determines the response deterioration of the air-fuel ratio sensor based on the state of change of the output of the air-fuel ratio sensor. Further, during the operation of the internal combustion engine, the calculated attachment/detachment state parameter and the attachment/detachment degree parameter are used at each predetermined cycle to calculate a dust accumulation increase/decrease parameter indicating an amount of accumulation of dust in the air-fuel ratio sensor, and the dust accumulation increase/decrease parameter is integrated to calculate a dust accumulation determination parameter indicating a current amount of accumulation of dust in the air-fuel ratio sensor. When the dust accumulation amount indicated by the dust accumulation determination parameter is larger than a prescribed amount, determination in response to deterioration is retained or inhibited.
Description
Technical Field
The present invention relates to a deterioration determination device for an air-fuel ratio sensor that determines deterioration in response of an air-fuel ratio sensor that detects an air-fuel ratio of exhaust gas of an internal combustion engine.
Background
The air-fuel ratio sensor is provided in an exhaust passage of an internal combustion engine, detects an air-fuel ratio of exhaust gas over a wide range, and uses the detection result for feedback control of the air-fuel ratio of the mixture gas, regeneration control of an exhaust gas purification device, and the like. In general, the deterioration of the air-fuel ratio sensor is determined because the deterioration of the air-fuel ratio sensor is accelerated as the sensor is used. Further, it is known that dust in the exhaust gas adheres to a cover of the air-fuel ratio sensor, and the responsiveness temporarily decreases when the deposition amount increases.
In view of the above characteristics, for example, patent document 1 describes a control device that prevents a decrease in the responsiveness of the air-fuel ratio sensor due to the accumulation of dust (particulate matter). In the control device, the amount of dust adhering to the air-fuel ratio sensor is estimated using a predetermined map based on the detected load and rotation speed of the internal combustion engine. When the estimated dust adhesion amount is the predetermined amount or more, dust (Particulate Matter (PM)) removal control for removing dust that has adhered to the air-fuel ratio sensor is executed as there is a fear that the responsiveness of the air-fuel ratio sensor deteriorates. The dust removal control is performed by: the intake air amount is increased to increase the exhaust flow rate, thereby blowing off the dust, and the exhaust temperature is raised to burn the dust.
[ Prior art documents ]
[ patent document ]
[ patent document 1] Japanese patent No. 6254411 publication
Disclosure of Invention
[ problems to be solved by the invention ]
As described above, the air-fuel ratio sensor has a characteristic in which the responsiveness is lowered when the accumulation amount of dust is large, but the degree of lowering of the responsiveness is not fixed even if the accumulation amount is the same. Further, the dust adhering to the air-fuel ratio sensor may be detached (peeled off) from the air-fuel ratio sensor depending on the subsequent operating state of the internal combustion engine, for example, when the high-load operation is performed, and in this case, the decrease in responsiveness is temporary, and the responsiveness may be restored.
In contrast, in the conventional control device, when the amount of dust adhering to the air-fuel ratio sensor estimated based on the load and the rotation speed of the internal combustion engine is equal to or greater than the predetermined amount, it is only determined that there is a possibility that the responsiveness of the air-fuel ratio sensor deteriorates, and the determination cannot be performed with high accuracy. Further, as described above, although there is a possibility that the decrease in responsiveness due to the accumulation of dust is temporary and then recovery is performed, when the dust adhesion amount is equal to or more than a predetermined amount, it is considered that there is a possibility that the responsiveness deteriorates and the dust removal control is executed uselessly.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a degradation determination device for an air-fuel ratio sensor, which can accurately determine the response degradation of the air-fuel ratio sensor while avoiding erroneous determination due to temporary reduction in responsiveness caused by accumulation of dust.
[ means for solving problems ]
In order to achieve the above object, the invention of claim 1 is an Air-fuel ratio sensor degradation determination device that determines a response degradation of an Air-fuel ratio sensor (in an embodiment, (hereinafter, the same in this case) AF (Air-fuel ratio) sensor 23) that is provided in an exhaust passage 5 and detects an Air-fuel ratio of exhaust gas of an internal combustion engine 3, the Air-fuel ratio sensor degradation determination device including: response deterioration determination means (ECU 2, step 2 of fig. 3, fig. 4) for determining response deterioration of the air-fuel ratio sensor based on a state of change of an output of the air-fuel ratio sensor when the air-fuel ratio of the exhaust gas changes; an attachment/detachment parameter calculation unit (ECU 2, steps 21 to 23, 25, and 26 of fig. 6) that calculates, at predetermined intervals during operation of the internal combustion engine 3, an attachment/detachment state parameter (increase/decrease sign value ctSign) indicating which state dust present in the exhaust gas is attached to the air-fuel ratio sensor or which state dust having attached thereto is detached from the air-fuel ratio sensor, and an attachment/detachment degree parameter (dust discharge amount counter value ctSoot, exhaust gas temperature counter value ctTemp, condensed water correction coefficient kdawdet, Hydrocarbon (HC) correction coefficient kHC) indicating a degree of influence of the dust on attachment or detachment of the air-fuel ratio sensor; a dust accumulation increase/decrease parameter calculation unit (ECU 2, step 13 of fig. 5, fig. 6) that calculates a dust accumulation increase/decrease parameter (dust accumulation increase/decrease counter value ctLAFAct) indicating an amount of accumulation of dust on the air-fuel ratio sensor, using the calculated adhesion/detachment state parameter and adhesion/detachment degree parameter at each predetermined cycle; dust accumulation determination parameter calculation means (ECU 2, step 14 in fig. 5) for calculating a dust accumulation determination parameter (dust accumulation determination counter value ctlaftll) indicating a current amount of dust accumulated in the air-fuel ratio sensor by integrating the calculated dust accumulation increase/decrease parameter at each predetermined cycle; and a determination retention means (ECU 2, step 4 and step 5 in FIG. 5) for retaining the determination of the response deterioration when the dust accumulation amount indicated by the calculated dust accumulation determination parameter is larger than a predetermined amount (predetermined value ctREF) when the determination of the response deterioration of the air-fuel ratio sensor by the response deterioration determination means is completed (step 4: NO in FIG. 3).
According to the deterioration determination device of the air-fuel ratio sensor, the response deterioration of the air-fuel ratio sensor is determined based on the actual change state of the output of the air-fuel ratio sensor obtained when the air-fuel ratio of the exhaust gas changes. Further, a dust accumulation determination parameter for permitting/retaining the determination result is calculated as follows. That is, during operation of the internal combustion engine, at first, at each predetermined cycle, an adhesion/detachment state parameter indicating the adhesion or detachment state of dust to/from the air-fuel ratio sensor and an adhesion/detachment degree parameter indicating the degree of influence of the adhesion or detachment of dust to/from the air-fuel ratio sensor are calculated. Further, at each predetermined cycle, a dust accumulation increase/decrease parameter indicating an amount of accumulation of dust in the air-fuel ratio sensor is calculated using the adhesion/detachment state parameter and the adhesion/detachment degree parameter, and the dust accumulation increase/decrease parameter is integrated to calculate a dust accumulation determination parameter indicating a current amount of accumulation of dust in the air-fuel ratio sensor.
With the above calculation method, it is possible to always accurately calculate a dust accumulation determination parameter indicating the current amount of accumulation of dust on the air-fuel ratio sensor at each predetermined cycle while referring to the state of attachment or detachment of dust and reflecting the degree of influence of the attachment or detachment of dust on the air-fuel ratio sensor.
Further, according to the present invention, when the determination of the response deterioration of the air-fuel ratio sensor is completed, and the dust accumulation amount indicated by the dust accumulation determination parameter at that time is larger than the predetermined amount, the determination of the response deterioration is retained as if there is a concern that the temporary decrease in the responsiveness of the air-fuel ratio sensor due to the accumulation of dust affects the determination result of the response deterioration. This avoids erroneous determination of response degradation. On the other hand, when the dust accumulation amount indicated by the dust accumulation determination parameter is equal to or less than the predetermined amount, it is considered that there is no possibility of erroneous determination, and determination of response deterioration is permitted. As described above, it is possible to accurately determine the response degradation of the air-fuel ratio sensor while avoiding erroneous determination due to temporary decrease in responsiveness caused by accumulation of dust.
In order to achieve the above object, the invention according to claim 2 provides a deterioration determination device for an air-fuel ratio sensor, which determines deterioration in response of an air-fuel ratio sensor (AF sensor 23) provided in an exhaust passage 5 and detecting an air-fuel ratio of exhaust gas of an internal combustion engine 3, the deterioration determination device comprising: response deterioration determination means (ECU 2, step 35 of fig. 13, fig. 4) for determining response deterioration of the air-fuel ratio sensor based on a state of change of an output of the air-fuel ratio sensor when the air-fuel ratio of the exhaust gas changes; an attachment/detachment parameter calculation unit (ECU 2, steps 21 to 23, 25, and 26 in fig. 6) that calculates, at predetermined intervals during operation of the internal combustion engine 3, an attachment/detachment state parameter (increase/decrease sign value ctSign) indicating whether dust present in exhaust gas is attached to the air-fuel ratio sensor or whether the attached dust is detached from the air-fuel ratio sensor is attached to the air-fuel ratio sensor or not, and an attachment/detachment degree parameter (dust discharge amount counter value ctSoot, exhaust gas temperature counter value ctTemp, condensed water correction coefficient kdawdet, and HC correction coefficient kHC) indicating a degree of influence of the dust on attachment or detachment of the air-fuel ratio sensor; a dust accumulation increase/decrease parameter calculation unit (ECU 2, step 13 of fig. 5, fig. 6) that calculates a dust accumulation increase/decrease parameter (dust accumulation increase/decrease counter value ctLAFAct) indicating an amount of accumulation of dust on the air-fuel ratio sensor, using the calculated adhesion/detachment state parameter and adhesion/detachment degree parameter at each predetermined cycle; dust accumulation determination parameter calculation means (ECU 2, step 14 in fig. 5) for calculating a dust accumulation determination parameter (dust accumulation determination counter value ctlaftll) indicating a current amount of dust accumulated in the air-fuel ratio sensor by integrating the calculated dust accumulation increase/decrease parameter at each predetermined cycle; and a determination prohibition unit (ECU 2, step 31 and step 32 in FIG. 13) that prohibits the determination of the response deterioration when the dust accumulation amount indicated by the calculated dust accumulation determination parameter is larger than a predetermined amount (predetermined value ctREF) (NO in step 31 in FIG. 13).
In the present invention, as in the case of claim 1, a dust accumulation determination parameter indicating the amount of dust accumulated in the air-fuel ratio sensor at present is calculated at each predetermined cycle using the attachment/detachment state parameter and the attachment/detachment degree parameter. Further, according to the present invention, when the dust accumulation amount indicated by the calculated dust accumulation determination parameter is larger than the predetermined amount, the determination of the response deterioration is prohibited, considering that there is a possibility that the temporary decrease in the responsiveness of the air-fuel ratio sensor due to the accumulation of dust affects the determination result of the response deterioration. This avoids erroneous determination of response degradation. On the other hand, when the dust accumulation amount indicated by the dust accumulation determination parameter is equal to or less than the predetermined amount, it is considered that there is no possibility of erroneous determination, and determination of response deterioration is permitted. As described above, similarly to the case of claim 1, it is possible to accurately determine the response degradation of the air-fuel ratio sensor while avoiding erroneous determination due to temporary decrease in responsiveness caused by accumulation of dust. In addition, the deterioration determination using the deterioration determining means that is retained in the case of claim 1 may be prohibited in advance.
The invention of claim 3 is characterized in that: in the degradation determination device for an air-fuel ratio sensor described in claim 1 or claim 2, the adhesion/detachment state parameter (increase/decrease sign value ctSign) is calculated so as to indicate the adhesion state when the estimated flow rate of the exhaust gas is small and indicate the detachment state when the estimated flow rate of the exhaust gas is large (fig. 8).
In general, the smaller the flow velocity of the exhaust gas, the longer the contact time of the exhaust gas with the air-fuel ratio sensor, and therefore the dust in the exhaust gas is likely to adhere to the air-fuel ratio sensor, whereas the larger the flow velocity of the exhaust gas, the more the dust that has adhered to the air-fuel ratio sensor is blown off by the exhaust gas, and is likely to detach from the air-fuel ratio sensor. According to the above configuration, since the adhesion/detachment state parameter is calculated in accordance with the flow velocity of the exhaust gas so as to match the tendency, the adhesion state or detachment state of the dust can be appropriately expressed by using the calculated adhesion/detachment state parameter.
The invention of claim 4 is characterized in that: the deterioration determination device for an air-fuel ratio sensor described in any one of claims 1 to 3 further includes a load acquisition means (an accelerator opening sensor 25) that acquires a load LE of the internal combustion engine 3, and a rotation speed acquisition means (a crank angle sensor 21) that acquires a rotation speed NE of the internal combustion engine 3, and the attachment/detachment parameter calculation means calculates, as an attachment/detachment degree parameter, a dust discharge amount parameter (a dust discharge amount counter value ctsot) that indicates a degree of influence of a discharge amount of dust from the internal combustion engine 3, based on the acquired load LE of the internal combustion engine 3 and the acquired rotation speed NE of the internal combustion engine 3 (step 21 of fig. 6, fig. 7).
In general, the amount of dust discharged from the internal combustion engine varies depending on the load and the rotation speed of the internal combustion engine, and has a large influence on the degree of attachment or detachment of the air-fuel ratio sensor by the dust. Therefore, in accordance with such a tendency, by calculating a dust discharge amount parameter indicating the degree of influence of the amount of dust discharged from the internal combustion engine based on the load and the rotation speed of the internal combustion engine obtained and using the calculated dust discharge amount parameter as the adhesion/detachment degree parameter, the calculation of the dust accumulation increase/decrease parameter and the dust accumulation determination parameter can be performed with higher accuracy.
The invention of claim 5 is characterized in that: the degradation determination device for an air-fuel ratio sensor described in any one of claims 1 to 4 further includes exhaust gas temperature acquisition means (exhaust gas temperature sensor 24) for acquiring a temperature of the exhaust gas (exhaust gas temperature TEX), and the attachment/detachment parameter calculation means calculates an exhaust gas temperature parameter (exhaust gas temperature counter value ctTemp) indicating a degree of influence exerted by the acquired temperature of the exhaust gas as an attachment/detachment degree parameter (step 23 of fig. 6, fig. 9).
In general, the lower the temperature of the exhaust gas, the more easily dust in the exhaust gas adheres to the air-fuel ratio sensor, and the higher the temperature of the exhaust gas, the more easily dust that has adhered to the air-fuel ratio sensor detaches. Therefore, by calculating an exhaust gas temperature parameter indicating the degree of influence of the acquired temperature of the exhaust gas so as to match this tendency, and using this as the adhesion/detachment degree parameter, the dust accumulation increase/decrease parameter and the dust accumulation determination parameter can be calculated with higher accuracy.
The invention of claim 6 is characterized in that: the degradation determination device for an air-fuel ratio sensor described in any one of claims 1 to 5 further includes an engine temperature acquisition means (water temperature sensor 26) that acquires a temperature TE of the engine 3, and the adhesion/detachment parameter calculation means calculates, as an adhesion/detachment degree parameter, a condensed water parameter (condensed water correction coefficient kDewdet) indicating a degree of influence of condensed water in the exhaust gas, based on the acquired temperature TE of the engine 3 (step 25 in fig. 6, fig. 10).
Generally, the lower the temperature of the internal combustion engine, the more easily moisture in the exhaust gas condenses, and the more condensed water, the more easily dust adheres. Therefore, in accordance with such a tendency, the condensed water parameter indicating the degree of influence of the condensed water in the exhaust gas is calculated based on the acquired temperature of the internal combustion engine, and the calculated condensed water parameter is used as the parameter of the degree of adhesion/detachment, whereby the dust accumulation increase/decrease parameter and the dust accumulation determination parameter can be calculated with higher accuracy.
The invention of claim 7 is characterized in that: in the degradation determination device for an air-fuel ratio sensor described in any one of claims 1 to 6, the adhesion/desorption parameter calculation means calculates, as the adhesion/desorption parameter, an HC parameter (HC correction coefficient kHC) indicating the degree of influence of an increase in HC components in the exhaust gas during rich control (rich control) of the internal combustion engine (step 26 in fig. 6, fig. 11).
During rich control of the internal combustion engine, the amount of dust adhering to the air-fuel ratio sensor increases because the unburned HC component in the exhaust gas increases as compared to during normal control. According to the above configuration, since the HC parameter indicating the degree of influence of the increase in the HC component in the exhaust gas during the rich control of the internal combustion engine is calculated as the adhesion/detachment degree parameter, the dust accumulation increase/decrease parameter and the dust accumulation determination parameter can be calculated with higher accuracy.
Drawings
Fig. 1 is a diagram schematically showing the configuration of an exhaust system of an internal combustion engine including an air-fuel ratio sensor to which the present invention is applied, together with the internal combustion engine.
Fig. 2 is a block diagram showing a deterioration determination device of an air-fuel ratio sensor together with an input/output element and the like.
Fig. 3 is a flowchart showing a deterioration determination process of the air-fuel ratio sensor performed by an Electronic Control Unit (ECU) shown in fig. 2 according to the first embodiment.
Fig. 4 is a diagram for explaining a method of deterioration determination.
Fig. 5 is a flowchart showing a process of calculating the dust accumulation determination counter value.
Fig. 6 is a flowchart showing a process of calculating the dust accumulation up-down counter value.
Fig. 7 is a graph for calculation of the dust discharge amount counter value.
Fig. 8 is a graph for increasing or decreasing the calculation of the symbol value.
Fig. 9 is a graph for calculation of the exhaust gas temperature counter value.
Fig. 10 is a graph for calculation of the condensate correction coefficient.
Fig. 11 is a graph for calculation of the HC correction coefficient.
Fig. 12 is a timing chart showing an operation example obtained by the degradation determination process of fig. 3.
Fig. 13 is a flowchart showing a deterioration determination process of the air-fuel ratio sensor performed by the ECU of fig. 2 in the second embodiment.
[ description of symbols ]
2: ECU (response deterioration determination means, attachment/detachment parameter calculation means, dust accumulation increase/decrease parameter calculation means, dust accumulation determination parameter calculation means, determination retention means, determination prohibition means)
3: internal combustion engine
5: exhaust passage
21: crank angle sensor (rotating speed acquisition component)
23: AF sensor (air-fuel ratio sensor)
24: exhaust temperature sensor (exhaust temperature acquisition component)
25: accelerator opening sensor (load acquisition component)
26: water temperature sensor (internal-combustion engine temperature acquisition component)
ctSign: increasing or decreasing sign value (attachment/detachment state parameter)
ctSoot: dust discharge amount counter value (attachment/detachment degree parameter)
ctTemp: exhaust gas temperature counter value (adhesion/detachment degree parameter)
kDewdet: coefficient of condensate correction (degree of adhesion/detachment parameter)
kHC: HC correction factor (degree of adhesion/detachment parameter)
ctLAFACt: dust accumulation up-down counter value (dust accumulation up-down parameter)
ctLAFTtl: dust accumulation determination counter value (dust accumulation determination parameter)
ctREF: specified value
LE: engine load (load of internal combustion engine)
NE: engine speed (speed of internal combustion engine)
TEX: exhaust temperature (temperature of exhaust gas)
TE: temperature of internal combustion engine
Detailed Description
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Fig. 1 shows an internal combustion engine including an air-fuel ratio sensor to which the present invention is applied in an exhaust system. The internal combustion Engine (ENG) (hereinafter referred to as "engine") 3 is, for example, a four-cylinder gasoline engine mounted on a vehicle (not shown).
An intake passage 4 and an exhaust passage 5 are connected to each cylinder (not shown) of the engine 3, and a fuel injection valve 6 and an ignition plug 7 are mounted (see fig. 2). The fuel injection valve 6 injects fuel supplied from a fuel tank into a combustion chamber (both not shown), and the ignition plug 7 ignites the mixture gas generated in the combustion chamber. The operation of the fuel injection valve 6 and the ignition plug 7 is controlled by a control signal from an ECU (electronic control unit) 2, thereby controlling the fuel injection amount and the fuel injection timing or the ignition timing.
A crank angle sensor 21 is provided on a crankshaft (not shown) of the engine 3. The crank angle sensor 21 outputs a CRK signal, which is a pulse signal, to the ECU 2 at every predetermined crank angle (for example, 30 degrees) in accordance with the rotation of the crankshaft. The ECU 2 calculates the rotation speed NE of the engine 3 (hereinafter referred to as "engine rotation speed") based on the CRK signal.
An airflow sensor 22 is provided in the intake passage 4. The airflow sensor 22 detects an intake air amount GAIR taken into the cylinders of the engine 3 via the intake passage 4, and outputs a detection signal thereof to the ECU 2. Since the intake air amount GAIR is substantially equal to the flow rate of the exhaust gas discharged from the cylinder, the ECU 2 calculates the exhaust gas flow rate QEX from the intake air amount GAIR.
In the exhaust passage 5, a turbine 8a of a turbocharger (T/C)8, a three-way Catalyst (CAT)9, and a Diesel Particulate Filter (DPF) 10 are provided in this order from the upstream side.
The turbine 8a of the turbocharger 8 is rotationally driven by exhaust energy, and a compressor (not shown) disposed in the intake passage 4 rotates integrally with the turbine 8a to perform a supercharging operation.
The three-way catalyst 9 purifies three components of CO, HC, and NOx in the exhaust gas when the exhaust gas is stoichiometric air corresponding to the stoichiometric air-fuel ratio. The DPF 10 traps Particulate Matter (PM) in the exhaust gas passing through the three-way catalyst 9. Further, when the amount of trapped particulate matter has reached a predetermined amount, for example, a regeneration operation is performed in which the particulate matter is burned, thereby regenerating the DPF 10.
Further, an AF sensor (air-fuel ratio sensor) 23 and an exhaust gas temperature sensor 24 are provided on the downstream side of the turbine 8a and on the upstream side of the three-way catalyst 9 in the exhaust passage 5. The AF sensor 23 is a well-known sensor including zirconia, platinum electrodes, and the like, and detects the oxygen concentration in the exhaust gas in a wide air-fuel ratio region from a rich region to an extremely lean region with respect to the stoichiometric air-fuel ratio, and outputs a detection signal thereof to the ECU 2. The ECU 2 calculates the air-fuel ratio of the exhaust gas flowing into the three-way catalyst 9 based on the detection signal of the AF sensor 23.
The exhaust gas temperature sensor 24 detects a temperature of the exhaust gas flowing into the three-way catalyst 9 (hereinafter referred to as "exhaust gas temperature") TEX, and outputs a detection signal thereof to the ECU 2.
Further, a detection signal indicating a depression amount (hereinafter referred to as "accelerator opening") AP of an accelerator pedal (not shown) of the vehicle is input from the accelerator opening sensor 25 to the ECU 2, and a detection signal indicating a temperature TW of cooling water of the engine 3 (hereinafter referred to as "engine water temperature") is input from the water temperature sensor 26 to the ECU 2.
The ECU 2 includes a microcomputer including a Central Processing Unit (CPU), a Random Access Memory (RAM), a Read Only Memory (ROM), a charged Erasable Programmable Read Only Memory (EEPROM), an Input/Output (I/O) interface (none of which is shown), and the like. The ECU 2 identifies the operating state of the engine 3 in response to the detection signals of the various sensors 21 to 26 and the like, and executes various controls in response to the identified operating state.
The control includes, in addition to engine control such as fuel injection control via the fuel injection valve 6 and ignition timing control via the ignition plug 7, deterioration determination for determining deterioration of the AF sensor 23 in the present embodiment. In the present embodiment, the ECU 2 corresponds to the response degradation determination means, the attachment/detachment parameter calculation means, the dust accumulation increase/decrease parameter calculation means, the dust accumulation determination parameter calculation means, and the determination retention means.
The deterioration determination process of the AF sensor 23 according to the first embodiment will be described below with reference to fig. 3. This degradation determination process determines the response degradation of the AF sensor 23 based on the state of change (transition) of the output of the AF sensor 23 when the exhaust gas air-fuel ratio has changed, and finally determines or retains the determination result based on a dust accumulation determination counter value ctlaftll indicating the accumulation amount of dust toward the AF sensor 23 when the determination is completed. This processing is executed at a predetermined cycle (for example, 10msec) during the operation of the engine 3.
In this process, first, in step 1 (illustrated as "S1". the same applies hereinafter), it is determined whether or not a determination condition for deterioration is satisfied. As the determination condition, it is necessary to greatly change the exhaust gas air-fuel ratio from a stable state to another exhaust gas air-fuel ratio. In the present embodiment, as shown in fig. 4, a condition is set such that the engine 3 has shifted from a predetermined cruise operation to a Fuel Cut (F/C) operation. When the answer of step 1 is no, the process is directly ended.
When the answer of step 1 is YES and the determination condition is satisfied, in step 2, deterioration determination of AF sensor 23 is performed. As shown in fig. 4, in the deterioration determination, the sensor output VO of the AF sensor 23 after the engine 3 is shifted from the cruise operation to the fuel cut operation is monitored. As a result, as shown as "normal" in the figure, when the rise time of the sensor output VO (the time required to change from the first predetermined value VO1 to the second predetermined value VO 2) is smaller and shorter than a predetermined value (not shown), the AF sensor 23 is determined to be normal with respect to responsiveness.
On the other hand, as shown in "deterioration 1", when the rise time of the sensor output VO is a predetermined value or more and is relatively long, it is determined that response deterioration has occurred in the AF sensor 23. As indicated by "deterioration 2", even if the sensor output VO does not reach the second predetermined value VO2 after the predetermined time TMREF elapses from the start of the fuel cut operation, it is determined that response deterioration has occurred in the AF sensor 23.
Returning to fig. 3, in step 3, it is determined whether the deterioration judgment in step 2 has been completed, and if the answer is no, the present process is ended as it is. On the other hand, if the answer in step 3 is yes, and the deterioration determination of the AF sensor 23 is completed, the flow proceeds to step 4, and it is determined whether or not the dust accumulation determination counter value ctlaftl calculated at this time point is equal to or greater than a predetermined value ctREF (for example, 0). As will be described later, a smaller value of the dust accumulation determination counter value ctlaftls indicates a larger dust accumulation amount of the AF sensor 23.
Therefore, when the answer of step 4 is no and the dust accumulation determination counter value ctlaftlis smaller than the predetermined value ctREF, the determination result obtained in step 2 is left without permission (step 5) as if the dust accumulation amount of the AF sensor 23 is large and a temporary response deterioration occurs in the AF sensor 23, which may cause an erroneous determination, and the determination permission flag F _ JDGOK is set to "0" to indicate this fact, and the present process is ended.
On the other hand, if the answer of step 4 is yes, and the dust accumulation determination counter value ctlaflt is equal to or greater than the predetermined value ctREF, the determination result of step 2 is permitted (step 6) assuming that the dust accumulation amount of the AF sensor 23 is small and the erroneous determination is not likely to occur, and the determination permission flag F _ JDGOK is set to "1" to indicate this, and the present process is ended.
Next, the process of calculating the dust accumulation determination counter value ctlaftll will be described with reference to fig. 5 to 11. In the main flow of fig. 5, first, in step 11, it is determined whether or not an ignition switch (not shown) is turned on in the current processing cycle. If the answer is yes, immediately after the start of the operation of the engine 3, the final value ctlafltlst of the dust accumulation determination counter value stored in the EEPROM of the ECU 2 at the end of the previous operation is set as the current initial value of the dust accumulation determination counter value ctlafltl (step 12).
After the above step 12 or when the answer to step 11 is no, the routine proceeds to step 13, where a dust accumulation up/down counter value ctLAFAct is calculated. As will be described later, the dust accumulation up-down counter value ctLAFAct indicates the amount of accumulation of dust on the AF sensor 23 in the current processing cycle.
Then, the routine proceeds to step 14, where the dust accumulation determination counter value ctlaftl obtained immediately before the determination is added to the dust accumulation up-down counter value ctLAFAct calculated in step 13, thereby calculating the current value of the dust accumulation determination counter value ctlaftl, and the present processing is terminated.
Fig. 6 shows the calculation process of the dust accumulation up/down counter value ctLAFAct. In this processing, first, in step 21, a dust discharge amount counter value ctSoot is calculated. The dust discharge amount counter value ctSoot represents the amount of dust discharged from the engine 3, and is calculated by searching the map of fig. 7 in accordance with the engine load LE and the engine speed NE. The engine load LE represents a load calculated based on the accelerator opening AP and the engine speed NE in percentage (%) with respect to the total load.
In the graph of fig. 7, based on the tendency of the discharge amount of dust from the engine 3, the dust discharge amount counter value ctroot is set so as to become maximum in the middle load region around 50%, equal to the engine speed NE, and become maximum in the middle rotation region around 2000rpm with respect to the engine load LE.
Next, at step 22, the increase/decrease sign value ctSign is calculated by searching the graph of fig. 8 according to the engine load LE and the engine speed NE. The plus/minus sign value ctSign is set to a negative value (-1) in an attached state where dust is attached to the AF sensor 23, and is set to a positive value (+1) in a detached state where the attached dust is detached from the air-fuel ratio sensor 23.
In the graph of fig. 8, in the middle-high load and middle-high rotation region, the increase/decrease sign value ctSign is set to a positive value because the flow rate of the exhaust gas is estimated to be large and the contact time of the exhaust gas with the AF sensor 23 is short, and in the low-load and low rotation region, the increase/decrease sign value ctSign is set to a negative value because the flow rate of the exhaust gas is estimated to be small and the contact time of the exhaust gas with the AF sensor 23 is long.
Then, in step 23, the exhaust gas temperature counter value ctTemp is calculated by searching the graph of fig. 9 in accordance with the detected exhaust gas temperature TEX. The exhaust temperature counter value ctTemp represents the degree of influence of the exhaust temperature TEX on attachment/detachment of dust. The higher the exhaust temperature TEX, the greater the degree of influence, so in the graph of fig. 9, the exhaust temperature influence counter value ctTemp is set to a value greater than 1.0 in the high temperature region of 400 ℃ or higher, and the higher the exhaust temperature TEX, the greater the exhaust temperature influence counter value ctTemp.
Then, the dust discharge amount counter value ctsot calculated in step 21 is multiplied by the plus/minus sign value ctSign and the exhaust gas temperature counter value ctTemp calculated in steps 22 and 23, thereby calculating a basic value ctBase of the dust accumulation up/down counter value ctLAFAct (step 24).
Then, in step 25, the condensation water correction coefficient kDewdet is calculated by searching the map of fig. 10 in accordance with the engine temperature TE. The condensed water correction coefficient kDewdet is used to compensate for an increase in the degree of adhesion of dust generated by condensation of moisture in the exhaust gas toward the AF sensor 23 at a low temperature of the engine 3. Therefore, in the map of fig. 10, the condensate correction coefficient kDewdet is set to a value larger than 1.0 in a low temperature region where the engine temperature TE is 60 ℃ or lower, and the condensate correction coefficient kDewdet is set to a larger value the lower the engine temperature TE is.
The engine temperature TE is a temperature representative of the engine 3, and in the present embodiment, the engine water temperature TW detected by the water temperature sensor 26 is used as it is as the engine temperature TE. As the engine temperature TE, for example, an intake air temperature or an oil temperature detected by another temperature sensor may be used instead of the engine water temperature TW, or an estimated value based on an operation time from the start of the engine 3 may be used.
Then, in step 26, the HC correction coefficient kHC is calculated using the map of fig. 11. The HC correction coefficient kHC is used to compensate for the increased amount of HC components in the exhaust gas when the engine 3 is rich controlled. Therefore, in the map of fig. 11, the HC correction coefficient kHC is set to a value of 1.0 during the normal control of the engine 3 and to a larger value of 1.1 during the rich control.
Finally, the dust accumulation up-down counter value ctLAFAct is calculated by multiplying the basic value ctBase calculated in the above-mentioned step 24 by the condensed water correction coefficient kDewdet and the HC correction coefficient kHC calculated in the steps 25 and 26 (step 27), and the present process is ended.
According to the above calculation method, the dust accumulation up-down counter value ctLAFAct indicates the amount of increase or decrease in the accumulation amount of dust in the AF sensor 23 for each processing cycle, and when it is estimated that the accumulation amount increases in the state where dust is already adhered to the AF sensor 23, the dust accumulation up-down counter value ctLAFAct is calculated as a negative value, and when it is estimated that the accumulation amount decreases in the detached state where dust is detached from the AF sensor 23, the dust accumulation up-down counter value ctLAFAct is calculated as a positive value. In addition, as described above, in step 14 of fig. 5, when the dust accumulation determination counter value ctlaftl is accumulated, the dust accumulation up-down counter value ctLAFAct is used as an addition term.
From the above relationship, the dust accumulation determination counter value ctlaftll decreases in the dust adhesion state, and a smaller value indicates a larger dust accumulation amount of the AF sensor 23. In contrast, the dust accumulation determination counter value ctlaftll is increased in the dust detached state, and the larger the value, the smaller the dust accumulation amount of the AF sensor 23.
Next, an operation example obtained by the deterioration determination process of the AF sensor 23 described so far will be described with reference to fig. 12. In this example, since the exhaust flow rate is small from time t0 to time t1, it is estimated that the dust is attached, the plus/minus sign value ctSign is set to-1, and the dust accumulation determination counter value ctLAFTtl is decreased from the value 0 in response to this. After time t1, the exhaust gas flow rate increases, and the dust detached state is estimated, and the increase/decrease sign value ctSign is set to +1, and the dust accumulation determination counter value ctlaftll increases.
In this state, at a time point t2, along with the transition to the fuel cut operation, the deterioration determination of the AF sensor 23 is performed (step 2 of fig. 3), and when the deterioration determination is completed (time point t3), the dust accumulation determination counter value ctlaftll is compared with a prescribed value ctREF (═ 0) (step 4). In this case, the dust accumulation determination counter value ctLAFTtl is smaller than 0 (step 4: no), and therefore the determination permission flag F _ JDGOK is maintained at "0" in consideration of the large dust accumulation amount of the AF sensor 23 while maintaining the deterioration determination of the AF sensor 23.
Thereafter, as the exhaust flow rate decreases and increases, the dust accumulation determination counter value ctlaftll decreases from time t4 and increases from time t 5. Also, at a time point t6, along with the transition to the fuel cut operation, the deterioration determination of the AF sensor 23 is performed. In this case, when the deterioration judgment is completed (time point t7), the dust accumulation judgment counter value ctlaftl is larger than 0 (step 4: yes), and therefore the judgment permission flag F _ JDGOK is set to "1" as the deterioration judgment of the AF sensor 23 is permitted in view of the small dust accumulation amount of the AF sensor 23.
As described above, according to the present embodiment, the response deterioration of the AF sensor 23 is determined based on the actual state of change of the output of the AF sensor 23 when the air-fuel ratio of the exhaust gas changes after the engine 3 shifts from the cruise operation to the fuel cut operation (fig. 4). During the operation of the engine 3, an adhesion/detachment state parameter (an increasing/decreasing sign value ctSign) indicating the adhesion or detachment state of dust to/from the AF sensor 23 and an adhesion/detachment degree parameter (a dust discharge amount counter value ctSoot, etc.) indicating the degree of influence of the adhesion or detachment of dust to/from the AF sensor 23 are calculated at predetermined intervals.
Further, a dust accumulation increasing/decreasing counter value ctLAFAct, which is a dust accumulation increasing/decreasing parameter indicating an amount of accumulation of dust on the AF sensor 23, is calculated using the adhesion/detachment state parameter and the adhesion/detachment degree parameter, and the dust accumulation increasing/decreasing counter value ctLAFAct is integrated, thereby calculating a dust accumulation determination counter value ctlaftll, which is a dust accumulation determination parameter indicating a current amount of accumulation of dust on the AF sensor 23.
With the above calculation method, the dust accumulation determination counter value ctlaftll indicating the amount of dust accumulated in the AF sensor 23 at present can be always calculated with high accuracy at a predetermined cycle while referring to the state of dust adhering to or separating from the AF sensor 23 and reflecting the degree of influence on the dust adhesion or separation.
When the determination of the response deterioration of the AF sensor 23 is completed, and the dust accumulation determination counter value ctlaflt at that time is smaller than the predetermined value ctREF, that is, when the dust accumulation amount indicated by the accumulation determination counter value ctlaflt is larger than the predetermined amount corresponding to the predetermined value ctREF, it is considered that the temporary decrease in the responsiveness of the air-fuel ratio sensor due to the accumulation of dust may affect the determination result of the response deterioration, and the determination of the response deterioration is retained. This avoids erroneous determination of response degradation.
On the other hand, when the dust accumulation determination counter value ctlaftll is equal to or greater than the predetermined value ctREF, that is, when the dust accumulation amount is greater than the predetermined amount, if the dust accumulation amount indicated by the dust accumulation determination parameter is equal to or less than the predetermined amount, it is considered that there is no possibility of an erroneous determination, and determination of response deterioration is permitted. As described above, it is possible to accurately determine the response degradation of the AF sensor 23 while avoiding erroneous determination due to temporary decrease in responsiveness caused by accumulation of dust.
Further, with the graph of fig. 8, when it is estimated that the flow rate of the exhaust gas is large based on the engine load LE and the engine speed NE, the plus/minus sign value ctSign as the attachment/detachment state parameter is set to a positive value indicating the detachment state of the dust, and when it is estimated that the flow rate of the exhaust gas is small, the plus/minus sign value ctSign as the attachment/detachment state parameter is set to a negative value indicating the attachment state of the dust. Accordingly, the up-down sign value ctSign can be calculated to appropriately indicate the attached state or detached state of the dust, and therefore, the dust accumulation up-down counter value ctLAFAct and the dust accumulation determination counter value ctLAFTtl using the up-down sign value ctSign can be calculated with higher accuracy.
Further, as the parameter of the degree of adhesion/detachment, the dust discharge amount counter value ctsot is calculated in accordance with the engine load LE and the engine speed NE from the map of fig. 7, the exhaust gas temperature counter value ctTemp is calculated in accordance with the exhaust gas temperature TEX from the map of fig. 9, the condensed water correction coefficient kDewdet is calculated in accordance with the engine temperature TE from the map of fig. 10, and the HC correction coefficient kHC is calculated in accordance with the operation mode of the engine 3 from fig. 11.
As described above, since the adhesion/detachment degree parameters can be calculated so as to appropriately indicate the degree of influence of dust on adhesion/detachment of the AF sensor 23, the dust accumulation up-down counter value ctLAFAct and the dust accumulation determination counter value ctlaftll using the adhesion/detachment degree parameters can be calculated with higher accuracy.
Next, with reference to fig. 13, a deterioration determination process of the AF sensor 23 according to the second embodiment of the present invention will be described. In the first embodiment (fig. 3), the deterioration determination of the AF sensor 23 is performed first, and the calculated dust accumulation determination parameter is performed simultaneously with the deterioration determination of the AF sensor 23, but the dust accumulation determination parameter is calculated first and the deterioration determination of the AF sensor 23 is prohibited depending on the calculation result.
Specifically, first, in step 31, similarly to step 4 in fig. 3, it is determined whether or not the dust accumulation determination counter value ctlaftll is equal to or greater than a predetermined value ctREF. Using the processing and the graphs of fig. 5 to 11, the dust accumulation determination counter value ctlaftll is calculated in the same manner as in the first embodiment.
If the answer at step 31 is no and ctlaflt < ctREF is true, the deterioration determination of the AF sensor 23 is prohibited (step 32) because it is considered that the dust deposition amount of the AF sensor 23 is large and a temporary response deterioration occurs in the AF sensor 23, which may cause an erroneous determination, and the determination permission flag F _ JDGOK2 is set to "0" to end the present process.
On the other hand, if the answer of step 31 is yes, ctlafltt ≧ ctREF is satisfied, deterioration determination of AF sensor 23 is permitted (step 33) in order to indicate that there is no possibility that erroneous determination will occur because the dust deposition amount of AF sensor 23 is small, and determination permission flag F _ JDGOK2 is set to "1". Then, it is determined whether or not a condition for deterioration determination of the AF sensor 23 is satisfied (step 34), and deterioration determination of the AF sensor 23 is performed in accordance with the satisfaction of the condition (step 35). By the method shown in fig. 4, deterioration determination of the AF sensor 23 is performed as in the first embodiment.
As described above, according to the present embodiment, when the dust accumulation determination counter value ctlaflt is smaller than the predetermined value ctREF, the deterioration determination of the AF sensor 23 is prohibited considering that there is a possibility that the temporary decrease in responsiveness of the AF sensor 23 due to the accumulation of dust affects the determination result of the response deterioration, and on the other hand, when the dust accumulation determination counter value ctlaflt is equal to or larger than the predetermined value ctREF, the deterioration determination of the AF sensor 23 is permitted. Thus, as in the first embodiment, it is possible to accurately determine the response degradation of the AF sensor 23 while avoiding erroneous determination due to temporary decrease in responsiveness caused by accumulation of dust. In addition, the deterioration determination of the AF sensor 23 that is left in the first embodiment may be prohibited in advance.
The present invention is not limited to the embodiments described above, and can be implemented in various forms. For example, in the embodiment, the increasing/decreasing sign value ctSign as the adhesion/detachment state parameter is calculated assuming the flow velocity of the exhaust gas based on the engine load LE and the engine speed NE, but the present invention is not limited thereto, and other appropriate parameters relating to the adhesion state or detachment state of the dust, for example, the flow rate of the exhaust gas may be used.
In the embodiment, the dust discharge amount counter value ctsot corresponding to the engine load LE and the engine speed NE, the exhaust gas temperature counter value ctTemp corresponding to the exhaust gas temperature TEX, the condensed water correction coefficient kDewdet corresponding to the engine temperature TE, and the HC correction coefficient kHC corresponding to the operation mode of the engine 3 are calculated as the adhesion/detachment degree parameters, but these parameters may be used together with other suitable parameters or may be replaced with other suitable parameters as long as they indicate the degree of influence on the adhesion or detachment of dust to the AF sensor 23. Further, in order to calculate the same parameter of the degree of adhesion/detachment, a parameter different from that of the embodiment may be used.
In the embodiment, an AF sensor including zirconia, a platinum electrode, and the like is used as an air-fuel ratio sensor, but the AF sensor is not limited to this, and any sensor may be used as long as it can detect the air-fuel ratio of the exhaust gas, and for example, a titania type oxygen concentration sensor or the like may be used.
Further, the embodiment is an example in which the present invention is applied to a gasoline engine, but the degradation determination device of the present invention is not limited thereto, and may be applied to various internal combustion engines, for example, a diesel engine. In addition, the structure of the fine portion may be appropriately changed within the scope of the gist of the present invention.
Claims (7)
1. A deterioration determination device for an air-fuel ratio sensor, which determines responsive deterioration of an air-fuel ratio sensor provided in an exhaust passage and detecting an air-fuel ratio of exhaust gas of an internal combustion engine, is characterized by comprising:
response deterioration determination means that determines response deterioration of the air-fuel ratio sensor based on a state of change in an output of the air-fuel ratio sensor when an air-fuel ratio of exhaust gas changes;
an attachment/detachment parameter calculation unit that calculates, at each predetermined cycle, an attachment/detachment state parameter indicating which of an attachment state of dust in exhaust gas to the air-fuel ratio sensor and a detachment state of the attached dust from the air-fuel ratio sensor and an attachment/detachment degree parameter indicating a degree of influence of the dust on attachment or detachment of the air-fuel ratio sensor, during operation of the internal combustion engine;
A dust accumulation increase/decrease parameter calculation unit that calculates a dust accumulation increase/decrease parameter indicating an amount of accumulation of dust on the air-fuel ratio sensor, using the calculated adhesion/detachment state parameter and adhesion/detachment degree parameter at each of the predetermined periods;
a dust accumulation determination parameter calculation unit configured to calculate a dust accumulation determination parameter indicating an amount of dust accumulated in the air-fuel ratio sensor at present by integrating the calculated dust accumulation increase/decrease parameter at each of the predetermined periods; and
and a determination retention means that retains the determination of the response deterioration when the dust accumulation amount indicated by the calculated dust accumulation determination parameter is larger than a predetermined amount in a case where the determination of the response deterioration of the air-fuel ratio sensor by the response deterioration determination means is completed.
2. A deterioration determination device for an air-fuel ratio sensor, which determines responsive deterioration of an air-fuel ratio sensor provided in an exhaust passage and detecting an air-fuel ratio of exhaust gas of an internal combustion engine, is characterized by comprising:
response deterioration determination means that determines response deterioration of the air-fuel ratio sensor based on a state of change in an output of the air-fuel ratio sensor when an air-fuel ratio of exhaust gas changes;
An attachment/detachment parameter calculation unit that calculates, at each predetermined cycle, an attachment/detachment state parameter indicating which of an attachment state of dust in exhaust gas to the air-fuel ratio sensor and a detachment state of the attached dust from the air-fuel ratio sensor and an attachment/detachment degree parameter indicating a degree of influence of the dust on attachment or detachment of the air-fuel ratio sensor, during operation of the internal combustion engine;
a dust accumulation increase/decrease parameter calculation unit that calculates a dust accumulation increase/decrease parameter indicating an amount of accumulation of dust on the air-fuel ratio sensor, using the calculated adhesion/detachment state parameter and adhesion/detachment degree parameter at each of the predetermined periods;
a dust accumulation determination parameter calculation unit configured to calculate a dust accumulation determination parameter indicating an amount of dust accumulated in the air-fuel ratio sensor at present by integrating the calculated dust accumulation increase/decrease parameter at each of the predetermined periods; and
and a determination prohibition unit that prohibits determination of response degradation of the air-fuel ratio sensor by the response degradation determination unit when the dust accumulation amount indicated by the calculated dust accumulation determination parameter is larger than a predetermined amount.
3. The degradation determination device of an air-fuel ratio sensor according to claim 1 or 2,
the adhesion/detachment state parameter is calculated so as to indicate the adhesion state when the estimated flow rate of the exhaust gas is small and indicate the detachment state when the estimated flow rate of the exhaust gas is large.
4. The degradation determination device of the air-fuel ratio sensor according to any one of claims 1 to 3, characterized by further comprising:
a load acquisition unit that acquires a load of the internal combustion engine; and
a rotational speed acquisition means that acquires a rotational speed of the internal combustion engine;
the attachment/detachment parameter calculation means calculates, as the attachment/detachment degree parameter, a dust discharge amount parameter indicating a degree of influence of a discharge amount of dust from the internal combustion engine, based on the acquired load of the internal combustion engine and the acquired rotation speed of the internal combustion engine.
5. The degradation determination device of the air-fuel ratio sensor according to any one of claims 1 to 4, characterized by further comprising:
an exhaust gas temperature acquisition means that acquires the temperature of exhaust gas;
the adhesion/detachment parameter calculation means calculates an exhaust gas temperature parameter indicating a degree of influence exerted by the acquired temperature of the exhaust gas as the adhesion/detachment degree parameter.
6. The degradation determination device of the air-fuel ratio sensor according to any one of claims 1 to 5, characterized by further comprising:
an internal combustion engine temperature acquisition means that acquires a temperature of the internal combustion engine;
the adhesion/detachment parameter calculating means calculates, as the adhesion/detachment degree parameter, a condensed water parameter indicating a degree of influence of condensed water in the exhaust gas, based on the acquired temperature of the internal combustion engine.
7. The degradation determination device of an air-fuel ratio sensor according to any one of claims 1 to 6,
the adhesion/desorption parameter calculation means calculates, as the adhesion/desorption parameter, a hydrocarbon amount parameter indicating a degree of influence of an increase in the amount of hydrocarbons in the exhaust gas during the rich control of the internal combustion engine.
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| JP6998416B2 (en) | 2022-01-18 |
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