JP2009013791A - Abnormality detection device, abnormality detection method and exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality detection device capable of reliably detecting abnormalities of a gas supply means when the gas supply means for supplying a gas containing oxygen is disposed in an exhaust path. <P>SOLUTION: An abnormality detection device which detects abnormalities of a gas supply means 21 for supplying a gas containing oxygen to an exhaust path 11 through which exhaust flows, includes an upstream side air-fuel ratio detection means 18 for detecting an air-fuel ratio of the exhaust at the upstream side in an exhaust flowing direction than a gas supply point 11a in the exhaust path by the gas supply means and a downstream side air-fuel ratio detection means 13 for detecting an air-fuel ratio of the exhaust at the downstream side in the exhaust flowing direction than the gas supply point in the exhaust path, and detects abnormalities of the gas supply means on the basis of detection results of the upstream side air-fuel ratio detection means and of the downstream side air-fuel ratio detection means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an abnormality detection device, an abnormality detection method, and an exhaust purification control device, and in particular, an abnormality detection device and an abnormality detection method for detecting an abnormality in a gas supply unit that supplies a gas containing oxygen to an exhaust path through which exhaust gas flows. , And an exhaust purification control apparatus including a gas supply means.

  A gas supply device (gas supply means) for supplying air (gas containing oxygen) may be provided in the exhaust path. For example, when the internal combustion engine is cold, the gas supply device is provided as means for quickly warming up the catalyst provided in the exhaust passage. When the catalyst is warmed up, the fuel injection amount is increased and air is supplied to the exhaust path upstream of the catalyst. In this case, the air-fuel ratio in the cylinder is made higher than the stoichiometric air-fuel ratio, and the exhaust gas generated there is reacted with oxygen in the supplied air to generate heat in the exhaust path. As a result, the temperature of the exhaust gas entering the catalyst increases, and the warm-up of the catalyst is promoted.

  When a gas supply device is provided in the exhaust path, it is desirable to detect whether air (gas containing oxygen) is normally supplied by the gas supply device. For example, it is conceivable to detect an abnormality in the gas supply device using an air-fuel ratio sensor or the like provided in the exhaust path. However, in this case, even if the detection result of the sensor indicating the abnormality of the gas supply device is obtained, the detection result is a result of detecting the abnormality of the gas supply device or the abnormality of the sensor itself. It may not be possible to determine whether it is a detection result.

  When a plurality of catalysts are provided in series in the exhaust path when the fuel injection amount is increased and air is supplied by the gas supply device in order to promote warming up of the catalyst, it is relatively downstream. In some cases, warm-up of the catalyst (downstream catalyst) provided on the side is not sufficiently promoted. For example, the air supplied by the gas supply device is guided to the exhaust path upstream of the catalyst (upstream catalyst) provided upstream of the plurality of catalysts. In this case, although it is effective for warming up the catalyst of the upstream side catalyst, there is a problem that the downstream side catalyst cannot be warmed up because exhaust gas that has generated heat does not come to the downstream side catalyst.

  Japanese Patent Laying-Open No. 2005-207403 (Patent Document 1) discloses a secondary air supply system for an internal combustion engine that accurately calculates a secondary air flow rate and thus contributes to improvement of exhaust emission.

  In the secondary air supply system for an internal combustion engine described in Patent Document 1, a secondary air pipe is connected upstream of the catalyst in the exhaust pipe, and a secondary air pump is provided upstream of the secondary air pipe. It has been. In addition, an on-off valve for opening and closing the secondary air pipe is provided downstream of the secondary air pump. A pressure sensor for detecting the pressure in the pipe is provided between the secondary air pump and the on-off valve. Based on the differential pressure between the secondary air supply pressure detected by the pressure sensor when the on-off valve is opened and the shut-off pressure detected by the pressure sensor when the on-off valve is closed under the operating condition of the secondary air pump, Calculate the flow rate.

  Japanese Patent Laid-Open No. 6-66133 (Patent Document 2) discloses an exhaust purification device for an internal combustion engine that improves exhaust purification performance in an internal combustion engine.

  In the exhaust gas purification apparatus for an internal combustion engine described in Patent Document 2, an exhaust passage on the upstream side of the catalyst is constituted by a main exhaust passage and a bypass passage that are parallel to each other, and an unburned gas adsorbent is interposed in the bypass passage. The switching valve for switching the flow path so that the exhaust gas selectively flows through both the main exhaust passage, the bypass passage, and the main exhaust passage and the bypass passage is controlled by the catalyst temperature and the adsorbent temperature, and is adsorbed by at least the adsorbent. In the vicinity of the unburned gas desorption temperature, the configuration is such that secondary air is supplied to the bypass passage on the upstream side of the adsorbent, thereby suppressing a rapid increase in the inlet temperature of the adsorbent, and in the desorption process of the adsorbent, Prevents deterioration of catalyst conversion efficiency without enriching the atmosphere in the catalyst.

JP-A-2005-207403 JP-A-6-66133 JP-A-6-10657

  When gas supply means for supplying a gas containing oxygen is provided in the exhaust path, it is desired that an abnormality in the gas supply means can be detected more reliably.

  When warming up the catalyst by supplying gas containing oxygen and rich exhaust gas upstream of the catalyst in the exhaust path in which a plurality of catalysts are provided in series, the catalyst provided relatively downstream In the past, sufficient consideration has not been given to warm-up.

  An object of the present invention is to provide an abnormality detection device that can detect an abnormality of a gas supply means more reliably when a gas supply means for supplying a gas containing oxygen is provided in an exhaust path.

  Another object of the present invention is to supply a gas containing oxygen and a rich exhaust gas to the upstream side of a catalyst in an exhaust path in which a plurality of catalysts are provided in series. It is an object of the present invention to provide an exhaust purification control device that can promote warm-up of a catalyst provided on the downstream side.

  The abnormality detection device of the present invention is an abnormality detection device for detecting an abnormality of a gas supply means for supplying a gas containing oxygen to an exhaust path through which exhaust gas flows, and the supply of the gas by the gas supply means in the exhaust path An upstream air-fuel ratio detection means for detecting an air-fuel ratio of the exhaust gas upstream of the location in the exhaust gas flow direction; and a downstream side of the exhaust gas flow direction from the gas supply location in the exhaust path Downstream air-fuel ratio detection means for detecting the air-fuel ratio of the exhaust gas, and the gas supply means based on the detection result of the upstream air-fuel ratio detection means and the detection result of the downstream air-fuel ratio detection means It is characterized by detecting abnormalities of

  In the abnormality detection device of the present invention, the exhaust gas is the exhaust gas discharged from an internal combustion engine, and the air-fuel ratio of the exhaust gas detected by the downstream air-fuel ratio detection means is the air-fuel ratio of the internal combustion engine. It is used for control.

  In the abnormality detection device of the present invention, the upstream air-fuel ratio detection means is provided in a bypass passage for bypassing the gas supply location and the downstream air-fuel ratio detection means to flow the exhaust gas, and the upstream air-fuel ratio The air-fuel ratio of the exhaust gas detected by the detecting means is used for detecting an abnormality in the bypass passage.

  The abnormality detection method of the present invention is an abnormality detection method for detecting an abnormality of a gas supply means for supplying a gas containing oxygen to an exhaust path through which exhaust gas flows, and the supply of the gas by the gas supply means in the exhaust path A step of detecting an air-fuel ratio of the exhaust gas upstream in the exhaust gas flow direction from the location; and a step of detecting the exhaust gas downstream in the exhaust gas flow direction from the gas supply location in the exhaust path. A step of detecting an air-fuel ratio, and a step of detecting an abnormality of the gas supply means based on the detection result of the air-fuel ratio of the exhaust gas on the upstream side and the detection result of the air-fuel ratio of the exhaust gas on the downstream side It is characterized by providing.

  The abnormality detection method of the present invention further includes a step of detecting an abnormality of the downstream air-fuel ratio detection means for detecting the air-fuel ratio of the exhaust gas on the downstream side.

  An exhaust purification control apparatus according to the present invention is provided in an exhaust path, an upstream catalyst that purifies exhaust gas flowing through the exhaust path, and an exhaust gas flow direction that is more than an installation position of the upstream catalyst in the exhaust path. An exhaust purification control device that controls an exhaust purification device that is provided on the downstream side and includes a downstream catalyst that purifies the exhaust gas flowing through the exhaust path, and that makes the exhaust gas flowing into the upstream catalyst rich Control means for controlling, and gas supply means for supplying a gas containing oxygen to the richly controlled exhaust gas on the upstream side in the exhaust gas flow direction from the installation position of the upstream catalyst in the exhaust path And the richly controlled exhaust gas on the upstream side in the flow direction of the exhaust gas from the gas supply position by the gas supply means in the exhaust path A bypass passage that bypasses the upstream catalyst and leads to the downstream catalyst, and a catalyst state detection estimation unit that detects or estimates the state of the upstream catalyst, and supplies the gas by the gas supply unit. When the exhaust gas is controlled to be rich by the control means, the rich degree of the exhaust gas to be controlled is set based on the state of the upstream catalyst detected or estimated by the catalyst state detection estimation means It is characterized by being.

  In the exhaust purification control apparatus of the present invention, when the state of the upstream catalyst reaches a predetermined state, the state of the upstream catalyst does not reach the predetermined state. The degree of richness of the exhaust gas to be controlled is set to a small value.

  According to the abnormality detection device of the present invention, when a gas supply means for supplying a gas containing oxygen is provided in the exhaust path, an abnormality of the gas supply means can be detected more reliably.

  Hereinafter, an embodiment of an abnormality detection device, an abnormality detection method, and an exhaust purification control device according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
The first embodiment will be described with reference to FIGS. 1 to 3. The present embodiment relates to an abnormality detection device and an abnormality detection method for detecting an abnormality of a gas supply unit that supplies a gas containing oxygen to an exhaust path through which exhaust gas flows, and an exhaust purification control device including the gas supply unit.

  In the present embodiment, air (oxygen is supplied to the exhaust pipe 11 in order to promote warm-up of the catalyst (see reference numerals 12 and 15 in FIG. 1) provided in the exhaust pipe (exhaust path, see reference numeral 11 in FIG. 1). An air pump (gas supply means, see reference numeral 21 in FIG. 1) is provided. The air-fuel ratio in the cylinder of the engine (internal combustion engine, see reference numeral 1 in FIG. 1) is made richer than the stoichiometric air-fuel ratio, and the exhaust gas generated therein reacts with oxygen in the air supplied by the air pump 21 to exhaust the exhaust gas. Heat is generated in the tube 11. The warming-up of the catalyst (12, 15) is promoted by the heat of the exhaust gas generated.

  In the present embodiment, abnormality detection is performed as to whether air is normally supplied to the exhaust pipe 11 by the air pump 21. Abnormality detection is performed based on the difference in the air-fuel ratio in the exhaust pipe 11 that occurs between when the air is normally supplied to the exhaust pipe 11 and when the air is not normally supplied.

  Abnormality detection is performed by a sensor (downstream air-fuel ratio detection means) that detects the air-fuel ratio of the exhaust gas downstream from the air introduction section (supply location, see reference numeral 11a in FIG. 1) into which air supplied by the air pump 21 is introduced. 1 and the detected value of the exhaust gas flowing through the bypass passage (see reference numeral 16 in FIG. 1), that is, a detection sensor (upstream air-fuel ratio detecting means, reference numeral in FIG. 1). 18). As will be described later, the bypass passage 16 allows the rich exhaust gas discharged from the engine 1 to flow upstream of the downstream catalyst 15 in order to promote warm-up of the catalyst (downstream catalyst) 15 provided on the downstream side. Provided to guide to the side. That is, the air-fuel ratio of the exhaust gas upstream of the air introduction part 11a is detected by the detection sensor 18.

  When air is normally supplied by the air pump 21, the exhaust gas flowing through the exhaust pipe 11 downstream of the air introduction portion 11a is in an excessive oxygen state, and the air-fuel ratio detected by the sensors (13, 14). Becomes lean. On the other hand, when air is not normally supplied by the air pump 21, the rich exhaust gas discharged from the engine 1 flows through the exhaust pipe 11 as it is. For this reason, the air-fuel ratio detected by the sensors (13, 14) becomes rich. Therefore, based on the detection results of the sensors (13, 14), it can be determined whether the air is normally supplied by the air pump 21.

  However, for example, even when the sensor (13, 14) is detected as rich, there is a possibility that it is erroneously detected as rich due to an abnormality in the sensor (13, 14) itself. For example, if the sensor (13, 14) in which the abnormality has occurred is detected as rich even though the air pump 21 is normal, it may be erroneously determined that the air pump 21 is abnormal. That is, there is a possibility that an erroneous determination is made in the abnormality detection of the air pump 21 only by the detection results of the sensors (13, 14).

  In the present embodiment, when performing abnormality detection, in addition to the detection values of the sensors (13, 14), that is, the detection value of the detection sensor 18 is referred to. As a result, it is confirmed whether the exhaust gas actually discharged from the engine 1 is rich or not, and the abnormality of the air pump 21 is detected based on the detection values of the sensors (13, 14). For example, when the exhaust gas discharged from the engine 1 is lean, even if the sensor (13, 14) detects that the exhaust gas is rich, it is not the abnormality of the air pump 21 but the abnormality of the sensor (13, 14). It becomes possible to judge. Therefore, as described later, when an abnormality occurs in the sensors (13, 14), erroneous determination in the abnormality detection of the air pump 21 is suppressed.

  In the present embodiment, the air supplied by the air pump 21 for promoting warm-up of the catalysts (12, 15) is guided to the exhaust pipe 11 upstream of the upstream catalyst 12 provided on the upstream side. In this case, the rich exhaust gas flowing through the exhaust pipe 11 reacts with oxygen mainly upstream of the upstream catalyst 12. Therefore, when all the rich exhaust gas discharged from the engine 1 flows into the upstream catalyst 12, much of the heat is absorbed by the upstream catalyst 12. Therefore, although it is effective for warming up the upstream catalyst 12, there is a problem that the catalyst cannot be warmed up because the exhaust gas that has generated heat does not come to the downstream catalyst 15 provided on the downstream side.

  In the present embodiment, a bypass passage (see reference numeral 16 in FIG. 1) is provided for guiding the rich exhaust gas discharged from the engine 1 to the upstream side of the downstream catalyst 15 by bypassing the upstream catalyst 12. Thereby, in the exhaust pipe 11 between the upstream catalyst 12 and the downstream catalyst 15, a reaction between the rich exhaust gas guided through the bypass passage 16 and oxygen in the air supplied by the air pump 21 occurs. . Therefore, warm-up of the downstream catalyst 15 is promoted, and the purification rate of the downstream catalyst 15 is improved.

  Further, in this embodiment, in order to promote the warm-up of the downstream catalyst 15, the richness of the exhaust gas discharged from the engine 1 is adjusted according to the active state of the upstream catalyst 12. After the upstream catalyst 12 is activated (warm-up is completed), the degree of richness of the exhaust gas is reduced as compared with before activation. As a result, as will be described below, the reaction between the fuel component in the exhaust gas and the oxygen in the air supplied by the air pump 21 is promoted in the exhaust pipe 11 upstream of the downstream catalyst 15.

  The temperature of the exhaust gas when flowing into the downstream catalyst 15 is lower than the temperature of the exhaust gas when flowing into the upstream catalyst 12. The ratio of oxygen and fuel components in the exhaust gas so that the oxygen and fuel components can react easily varies with temperature. In the case of low temperature, the reaction becomes easier when the ratio of the fuel component to oxygen is lowered than in the case of high temperature.

  Therefore, before the upstream side catalyst 12 is activated, a more advantageous situation for warming up the upstream side catalyst 12 can be realized by supplying exhaust gas having a high degree of richness. On the other hand, after the upstream side catalyst 12 is activated, it is possible to make the situation more advantageous for warming up the downstream side catalyst 15 by supplying exhaust gas having a reduced richness. Thereby, not only the warming-up of the upstream catalyst 12 is performed quickly, but also the warming-up of the downstream catalyst 15 can be further promoted.

  FIG. 1 is a schematic configuration diagram of an apparatus according to the present embodiment. In FIG. 1, reference numeral 1 denotes an engine (internal combustion engine). An intake manifold 2 is connected to the engine 1. An intake pipe 3 is connected to the intake manifold 2. An air cleaner 4 is provided in the intake pipe 3. A throttle valve 5 is provided in the intake pipe 3 on the downstream side of the installation position of the air cleaner 4. The intake pipe 3 is provided with a throttle sensor 6 for detecting the opening degree of the throttle valve 5. The intake pipe 3 is provided with an air flow meter 7 that detects the amount of air supplied to the engine 1.

  An exhaust manifold (exhaust path) 10 is connected to the engine 1. An exhaust pipe (exhaust path) 11 is connected to the exhaust manifold 10. The exhaust pipe 11 is provided with an upstream catalyst 12 and a downstream catalyst 15 that purify the exhaust gas. The downstream catalyst 15 is provided on the downstream side in the exhaust gas flow direction in the exhaust pipe 11 from the installation position of the upstream catalyst 12. The catalyst (12, 15) is a so-called three-way catalyst that simultaneously removes three substances of hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) by an oxidation / reduction reaction. it can.

  An oxygen sensor (A / F sensor) 13 is provided upstream of the upstream side catalyst 12 in the exhaust pipe 11 in the exhaust gas flow direction. The A / F sensor 13 is an oxygen sensor that exhibits linear output characteristics with respect to the air-fuel ratio. The A / F sensor 13 detects the air-fuel ratio of the exhaust gas flowing into the upstream catalyst 12.

  A catalyst control control sensor 14 is provided on the exhaust pipe 11 downstream of the upstream side catalyst 12 in the exhaust gas flow direction. The catalyst control control sensor 14 has a characteristic that the output greatly changes depending on whether the exhaust gas to be detected is richer or leaner than the stoichiometric air-fuel ratio. The catalyst control control sensor 14 detects whether the air-fuel ratio of the exhaust gas flowing out from the upstream catalyst 12 is rich or lean with respect to the stoichiometric air-fuel ratio.

  A bypass passage 16 that bypasses the upstream catalyst 12 is connected to an exhaust path including the exhaust manifold 10 and the exhaust pipe 11. One end of the bypass passage 16 is connected to the exhaust manifold 10 at the upstream connection portion 25 of the exhaust manifold 10. The other end of the bypass passage 16 is connected to the exhaust pipe 11 at a downstream connection portion 11 b between the installation position of the catalyst control control sensor 14 and the installation position of the downstream catalyst 15 in the exhaust pipe 11. Exhaust gas upstream of the upstream catalyst 12 is supplied to the downstream catalyst 15 by the bypass passage 16.

  An air pump 21 that supplies air (a gas containing oxygen) to the exhaust pipe 11 is connected to the exhaust pipe 11. The air pump 21 is connected to the exhaust pipe 11 via the air supply passage 22. The air supply passage 22 is connected to the exhaust pipe 11 in the air introduction part 11 a upstream of the installation position of the A / F sensor 13 in the exhaust pipe 11. The air introduction part 11a is set to be downstream from the upstream connection part 25 in the exhaust path. This is because the exhaust gas discharged from the engine 1, that is, the exhaust gas not mixed with the air supplied by the air pump 21, flows into the bypass passage 16.

  The air supply passage 22 is provided with an on-off valve 23 that opens and closes the air supply passage 22. The bypass passage 16 is provided with a detection sensor 18 for detecting the air-fuel ratio of the exhaust gas flowing through the bypass passage 16. That is, the detection sensor 18 can be, for example, an oxygen sensor similar to the A / F sensor 13. That is, the detection sensor 18 can detect the air-fuel ratio of the exhaust gas in the state where the air supplied by the air pump 21 is not mixed (the exhaust gas discharged from the engine 1).

  A vehicle (not shown) on which the engine 1 is mounted is provided with a vehicle control unit 20 having an ECU (Electronic Control Unit) that controls each part of the vehicle. A throttle sensor 6, an air flow meter 7, an A / F sensor 13, a catalyst control control sensor 14, and a detection sensor 18 are connected to the vehicle control unit 20, and signals indicating the respective detection results are transmitted to the vehicle control unit. 20 is input.

  The air pump 21 and the on-off valve 23 are connected to the vehicle control unit 20 and are controlled by the vehicle control unit 20, respectively. The engine 1 is connected to the vehicle control unit 20, and the operation of the engine 1 such as the fuel injection amount and the ignition timing is controlled by the vehicle control unit 20. The vehicle control unit 20 has functions as a control unit and a catalyst state detection estimation unit of the present embodiment.

  The vehicle control unit 20 controls the air-fuel ratio of the air-fuel mixture supplied to the engine 1 based on information input from the A / F sensor 13 and the catalyst control control sensor 14. Specifically, the fuel injection amount is feedback controlled (exhaust gas control control) based on the air-fuel ratio detected by the A / F sensor 13. Based on the deviation of the air-fuel ratio detected by the A / F sensor 13 from the target air-fuel ratio, a correction amount for the fuel injection amount so that the air-fuel ratio of the air-fuel mixture becomes the target air-fuel ratio (exhaust gas control fuel correction amount) Is set.

  In addition to the exhaust gas control control, feedback control (catalyst control control) for the fuel injection amount is performed based on the air-fuel ratio detected by the catalyst control control sensor 14. Based on the air-fuel ratio detected by the catalyst control control sensor 14, a correction amount (catalyst control fuel correction amount) is set for the fuel injection amount so that the air-fuel ratio approaches the stoichiometric air-fuel ratio.

  The operation of this embodiment will be described with reference to FIGS. FIG. 2 is a time chart when the control of this embodiment is performed. FIG. 3 is a flowchart showing the operation of the present embodiment.

  2, (a) is the fuel injection amount, (b) is the air pump start flag, (c) is the air pump failure flag, (d) is the detected value of the A / F sensor (engine exhaust gas control sensor) 13, (e ) Indicates the detection value of the catalyst control control sensor 14, (f) indicates the detection value of the detection sensor 18, and (g) indicates the temperature of the downstream catalyst 15.

  In FIG. 2, solid lines (reference numerals 201, 203, 205, 207, 209, 211, and 213) indicate transitions of respective values when air is normally supplied by the air pump 21, and broken lines (reference numerals 202, 204, 206, 208, 210, 212, 214) indicate transitions of respective values when air is not normally supplied by the air pump 21.

  The operation of this embodiment will be described with reference to the flowchart of FIG.

  In step S10, the vehicle control unit 20 determines whether or not the bypass passage 16 has been detected. The clogging of the bypass passage 16 can be detected by a known clogging detection method. That is, as a result of detection, if it is determined that no clogging has occurred in the bypass passage 16, an affirmative determination is made in step S10. The determination in step S10 is performed based on, for example, a comparison result between the detection values (211 and 212) of the detection sensor 18 and the detection values (207 and 208) of the A / F sensor 13. As a result of the determination, that is, when it is determined that it has been detected (step S10-Y), the process proceeds to step S20, and when not (step S10-N), this control flow ends.

  In step S20, the vehicle control unit 20 determines whether the A / F sensor 13, the catalyst control control sensor 14, and the detection sensor 18 are operating normally. The determination in step S20 is performed based on a signal indicating the detection result of each sensor (13, 14, 18), for example. As a result of the determination, when it is determined that the A / F sensor 13, the catalyst control control sensor 14, and the detection sensor 18 are operating normally (step S20-Y), the process proceeds to step S30. Otherwise (step S20-N), this control flow is terminated.

  In step S <b> 30, the air pump 21 is driven by the vehicle control unit 20. In the example shown in FIG. 2, the air pump 21 is driven at time T1. The amount of air supplied by the air pump 21 is set based on the amount of oxygen that can sufficiently react the fuel component and the like in the exhaust gas when the fuel injection amount is increased in step S60 described later. When step S30 is executed, the process proceeds to step S40.

  In step S40, the air pump activation flag (203, 204) is turned ON by the vehicle control unit 20. When step S40 is executed, the process proceeds to step S50.

  In step S50, the on-off valve 23 is opened by the vehicle control unit 20. Thereby, the air pumped by the air pump 21 is supplied to the exhaust pipe 11 through the air supply passage 22. When step S50 is executed, the process proceeds to step S60.

  In step S60, the vehicle control unit 20 increases the fuel injection amount. In step S60, the amount of fuel supplied to the engine 1 is set to a value larger than the amount corresponding to the theoretical air-fuel ratio. In the example shown in FIG. 2, the fuel injection amount (201, 202) is increased at time T1. As a result, the exhaust gas discharged from the engine 1 becomes rich. Thus, rich exhaust gas and oxygen in the air supplied by the air pump 21 react to generate heat, and catalyst warm-up is realized. In the downstream catalyst 15, warm-up is promoted by the reaction heat of rich exhaust gas supplied through the bypass passage 16. Thereby, the temperature 213 of the downstream catalyst 15 rises. When step S60 is executed, the process proceeds to step S70.

  In step S70, the vehicle control unit 20 causes both the detection values (207, 208) of the A / F sensor 13 and the detection values (209, 210) of the catalyst control control sensor 14 to be lean, that is, the detection sensor 18. It is determined whether the detected values (211 and 212) are rich. In step S <b> 70, it is determined whether air is normally supplied by the air pump 21.

  In response to the fuel injection amount (201, 202) being increased in step S60 and the exhaust gas exhausted from the engine 1 becoming rich, that is, the detection values (211 and 212) of the detection sensor 18 are rich. Indicates. As described above, that is, the detection sensor 18 detects the air-fuel ratio of the exhaust gas discharged from the engine 1. Therefore, whether or not air is normally supplied by the air pump 21 does not affect the detection values (211 and 212) of the detection sensor 18.

  In contrast, the detection values (207, 208) of the A / F sensor 13 and the detection values (209, 210) of the catalyst control control sensor 14 depend on whether air is normally supplied by the air pump 21 or not. Indicates a different value.

  When air is normally supplied by the air pump 21, the exhaust gas is in an excessive oxygen state. In this case, the detection value 207 of the A / F sensor 13 and the detection value 209 of the catalyst control control sensor 14 are both lean. Therefore, when both the detection value 207 of the A / F sensor 13 and the detection value 209 of the catalyst control control sensor 14 are lean, it can be determined that the air is supplied normally by the air pump 21. . However, even if air is not normally supplied by the air pump 21, the detection value 207 of the A / F sensor 13 and the detection value 209 of the catalyst control control sensor 14 may both indicate lean. For example, this is the case when the air-fuel ratio of the exhaust gas discharged from the engine 1 is lean for some reason.

  In the present embodiment, in addition to the detection values (207, 208) of the A / F sensor 13 and the detection values (209, 210) of the catalyst control control sensor 14, that is, the detection values (211 and 212) of the detection sensor 18. Is referred to, it can be more reliably determined whether or not air is normally supplied by the air pump 21. As a condition for determining that air is normally supplied by the air pump 21, the condition is that the detection value 207 of the A / F sensor 13 and the detection value 209 of the catalyst control control sensor 14 are both lean. By adding a condition that the detection value 211 of the detection sensor 18 is rich (rich exhaust gas is actually exhausted from the engine 1), erroneous determination is suppressed.

  The detection values (207, 208) of the A / F sensor 13 and the detection values (209, 210) of the catalyst control control sensor 14 are both lean, that is, the detection values (211, 212) of the detection sensor 18. Is not satisfied (step S70-N), there is an abnormality in the A / F sensor 13 or the catalyst control control sensor 14 in addition to the case where air is not normally supplied by the air pump 21. There may be a case where In this case, the process proceeds to a determination (step S150) as to whether the air pump 21 is abnormal or the sensor (13, 14) is abnormal.

  As a result of the determination in step S70, it is determined that the detection value 207 of the A / F sensor 13 and the detection value 209 of the catalyst control control sensor 14 are both lean, that is, the detection value 211 of the detection sensor 18 is rich. If so (step S70-Y), the process proceeds to step S80. If not (step S70-N), the process proceeds to step S150.

  In step S80, the vehicle control unit 20 determines that air is normally supplied by the air pump 21, and proceeds to step S90.

  In step S90, the vehicle control unit 20 determines whether or not the warm-up determination of the upstream catalyst 12 has been performed. The determination in step S90 is performed based on, for example, an integrated value (integrated air amount) of the air amount supplied to the engine 1. If it is determined that the upstream catalyst 12 has been warmed up (upstream catalyst 12 is activated), an affirmative determination is made in step S90.

  As a result of the determination in step S90, if it is determined that the warm-up determination of the upstream catalyst 12 has been performed (step S90-Y), the process proceeds to step S100, and if not (step S90-N), the process proceeds to step S90. Proceed to S110.

  In step S100, the vehicle control unit 20 reduces the fuel injection amount. In the example illustrated in FIG. 2, the warm-up determination of the upstream catalyst 12 is performed at time T3, and the fuel injection amount 201 is decreased. In step S100, the air-fuel ratio of the exhaust gas discharged from the engine 1 is adjusted so that the warm-up of the downstream catalyst 15 is further promoted. The degree of richness in the air-fuel ratio of the intake air supplied to the engine 1 is reduced.

  As a result, the exhaust gas discharged from the engine 1 after step S100 is executed is richer than the stoichiometric air-fuel ratio, but the air-fuel ratio becomes closer to the stoichiometric air-fuel ratio than before the step S100 is executed. Therefore, the exhaust pipe 11 upstream of the downstream catalyst 15 is in a state (ratio) in which the fuel component in the exhaust gas and the oxygen in the air supplied by the air pump 21 are likely to react. As a result, warming up of the downstream catalyst 15 is promoted. When step S100 is executed, the process proceeds to step S110.

  In step S110, the vehicle control unit 20 determines whether or not the warm-up determination of the downstream catalyst 15 has been performed. The determination in step S110 is performed based on, for example, an integrated value (integrated air amount) of the air amount supplied to the engine 1. If it is determined that the downstream catalyst 15 has been warmed up (the downstream catalyst 15 is activated), an affirmative determination is made in step S110.

  As a result of the determination in step S110, when it is determined that the warm-up determination of the downstream catalyst 15 has been performed (step S110-Y), the process proceeds to step S120, and otherwise (step S110-N) The control flow is terminated.

  In step S <b> 120, the on-off valve 23 is closed by the vehicle control unit 20. When step S120 is executed, the process proceeds to step S130.

  In step S130, the air pump 21 is stopped by the vehicle control unit 20. After step S130, the process proceeds to step S140.

  In step S140, the vehicle control unit 20 turns off the air pump activation flag 203. In the example shown in FIG. 2, the air pump activation flag 203 is turned off at time T4. When step S140 is executed, the control flow ends.

  If a negative determination is made in step S70 and the process proceeds to step S150, in step S150, the vehicle control unit 20 detects the detected values (207, 208) of the A / F sensor 13 and the detected values (209, 209) of the catalyst control control sensor 14. 210), that is, whether or not the detection values (211 and 212) of the detection sensor 18 are all rich. In step S150, whether the detection result indicating the abnormality in the A / F sensor 13 or the catalyst control control sensor 14 truly detects the abnormality of the air pump 21, or whether the A / F sensor 13 or the catalyst control control sensor 14 itself is detected. It is determined whether it is due to an abnormality or the like.

  When the air-fuel ratio of the exhaust gas discharged from the engine 1 (that is, the detection value 212 of the detection sensor 18) is rich, if the air is not normally supplied by the air pump 21, the rich exhaust gas remains as it is in the exhaust pipe 11. Flowing. Therefore, if both the detection value 208 of the A / F sensor 13 and the detection value 210 of the catalyst control control sensor 14 are rich, it can be determined that the air supply by the air pump 21 is not normally performed.

  On the other hand, the detection values (207, 208) of the A / F sensor 13, the detection values (209, 210) of the catalyst control control sensor 14, and the detection values (211, 212) of the detection sensor 18 are all rich. In other cases, there is a high possibility that the A / F sensor 13 or the catalyst control control sensor 14 itself is abnormal. For example, when the detection results are different between the A / F sensor 13 and the catalyst control control sensor 14, it is considered that there is any abnormality. Alternatively, the A / F sensor 13 or the catalyst control control sensor 14 detects that the air-fuel ratio of the exhaust gas discharged from the engine 1 (that is, the detection values 211 and 212 of the detection sensor 18) is not rich. If it is detected that the sensor is abnormal, it can be determined that the sensor is abnormal.

  When it is determined that one of the A / F sensor 13 and the catalyst control control sensor 14 is abnormal, the detection value of the other sensor, that is, the detection values (211 and 212) of the detection sensor 18 Based on the above, a re-determination can be performed as to whether air is normally supplied by the air pump 21.

  As a result of the determination in step S150, when it is determined that the detection value 208 of the A / F sensor 13, the detection value 210 of the catalyst control control sensor 14, and the detection value 212 of the detection sensor 18 are all rich (step S150). -Y), the process proceeds to step S160; otherwise (step S150-N), the process proceeds to step S190.

  In step S160, the vehicle control unit 20 determines that air is not normally supplied due to an abnormality such as a failure of the air pump 21, a clogging of the air supply passage 22, an operation failure of the on-off valve 23, or the like. After step S160, the process proceeds to step S170.

  In step S170, the air pump failure flag 206 is turned on by the vehicle control unit 20. In the example shown in FIG. 2, it is determined that the air pump 21 has failed at time T2, and the air pump failure flag 206 is turned ON. When step S170 is executed, the process proceeds to step S180.

  In step S180, the on-off valve 23 is closed by the vehicle control unit 20. When step S180 is executed, the control flow ends.

  When a negative determination is made in step S150 and the process proceeds to step S190, in step S190, the vehicle control unit 20 determines that an abnormality has occurred in the A / F sensor 13 or the catalyst control control sensor 14. The condition for proceeding to step S190 includes a case where the air-fuel ratio of the exhaust gas discharged from the engine 1 is lean for some reason. In this case, the detection value 207 of the A / F sensor 13 and the detection value 209 of the catalyst control control sensor 14 are both lean regardless of whether air is normally supplied by the air pump 21. In this case, when the air-fuel ratio of the exhaust gas discharged from the engine 1 becomes rich as desired, abnormality detection of the air pump 21 can be performed again based on this control flow. When step S190 is executed, this control flow ends.

  According to the present embodiment, the bypass passage 16 is provided in the exhaust path including the exhaust manifold 10 and the exhaust pipe 11 to guide the exhaust gas upstream of the air introduction portion 11a to the downstream catalyst 15. As a result, air is supplied from the air pump 21 (step S30) and the exhaust gas of the engine 1 is made rich (step S60). When the catalyst warm-up is performed, the exhaust pipe 11 on the upstream side of the downstream catalyst 15 is rich. Exhaust gas and oxygen react to generate heat. Therefore, warm-up of the downstream catalyst 15 is promoted, and the purification rate of the downstream catalyst 15 is improved.

  Further, when the warm-up determination is performed on the assumption that the upstream catalyst 12 is activated (step S90-Y), the fuel injection amount is compared with the case where the warm-up determination is not performed (step S90-N). Is reduced (step S100). Thereby, after the warm-up determination of the upstream catalyst 12, the fuel component in the exhaust gas and oxygen in the exhaust pipe 11 upstream of the downstream catalyst 15 are more likely to react. Therefore, the warm-up of the downstream catalyst 15 can be promoted as compared with the case where the fuel injection amount is not changed after the warm-up determination of the upstream catalyst 12.

  In this embodiment, whether or not air is normally supplied by the air pump 21 is determined in addition to the detection values of the A / F sensor 13 and the catalyst control control sensor 14, that is, the detection value of the detection sensor 18. Based on. Accordingly, it is possible to suppress erroneous determination that the air pump 21 is abnormal even though the A / F sensor 13 or the catalyst control control sensor 14 itself is abnormal. Therefore, it can be more reliably determined whether or not air is normally supplied by the air pump 21 as compared with the case where the detection value of the detection sensor 18 is not referred to.

  In the present embodiment, abnormality detection is performed using the A / F sensor 13 and the catalyst control control sensor 14 used for air-fuel ratio control, and the detection sensor 18 used for detection of the bypass passage 16. Therefore, the abnormality of the air pump 21 can be detected without newly providing a sensor for detecting the abnormality.

(First modification of the first embodiment)
A first modification of the first embodiment will be described.

  In the first embodiment, when the abnormality determination of the air pump 21 is performed, the detected value of the A / F sensor 13 and the catalyst control control are detected as the detected value of the air-fuel ratio in the exhaust pipe 11 downstream of the air introduction part 11a. Both of the detected values of the sensor 14 are used, but only one of the values may be referred to.

  For example, the case where the detection value of the A / F sensor 13 is used as the detection value of the air-fuel ratio in the exhaust pipe 11 on the downstream side of the air introduction part 11a will be described. It is determined whether or not the detection values (207 and 208) of the F sensor 13 are lean, that is, whether or not the detection values (211 and 212) of the detection sensor 18 are rich.

  In step S150, the vehicle control unit 20 determines whether the detection values (207, 208) of the A / F sensor 13 and the detection values (211, 212) of the detection sensor 18 are both rich. The

1 is a schematic configuration diagram of an apparatus according to a first embodiment of an abnormality detection apparatus, an abnormality detection method, and an exhaust purification control apparatus of the present invention. It is a time chart in case control of 1st Embodiment of the abnormality detection apparatus of this invention, the abnormality detection method, and an exhaust gas purification control apparatus is performed. It is a flowchart which shows operation | movement of 1st Embodiment of the abnormality detection apparatus of this invention, the abnormality detection method, and an exhaust gas purification control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Intake manifold 3 Intake pipe 4 Air cleaner 5 Throttle valve 6 Throttle sensor 7 Air flow meter 10 Exhaust manifold 11 Exhaust pipe 11a Air introduction part 11b Downstream side connection part 12 Upstream catalyst 13 A / F sensor 14 Catalyst control control sensor 15 Downstream catalyst 16 Bypass passage 18 That is, detection sensor 20 Vehicle control unit 21 Air pump 22 Air supply passage 23 On-off valve 25 Upstream side connection portion 201, 202 Fuel injection amount 203, 204 Air pump activation flag 205, 206 Air pump failure flag 207, 208 A / F sensor detection value 209, 210 Catalyst control control sensor detection value 211, 212 That is, detection sensor detection value 213, 214 Downstream catalyst temperature

Claims (7)

An abnormality detection device for detecting an abnormality of a gas supply means for supplying a gas containing oxygen to an exhaust path through which exhaust gas flows,
An upstream air-fuel ratio detection means for detecting an air-fuel ratio of the exhaust gas upstream of the gas supply position by the gas supply means in the exhaust path in the exhaust gas flow direction;
A downstream air-fuel ratio detecting means for detecting an air-fuel ratio of the exhaust gas downstream of the gas supply location in the exhaust path in the exhaust gas flow direction;
An abnormality detection device, wherein an abnormality of the gas supply means is detected based on a detection result of the upstream air-fuel ratio detection means and a detection result of the downstream air-fuel ratio detection means. The abnormality detection device according to claim 1,
The exhaust gas is the exhaust gas discharged from an internal combustion engine;
The abnormality detection device, wherein the air-fuel ratio of the exhaust gas detected by the downstream air-fuel ratio detection means is used for air-fuel ratio control of the internal combustion engine. In the abnormality detection device according to claim 1 or 2,
The upstream air-fuel ratio detection means is provided in a bypass passage for bypassing the gas supply location and the downstream air-fuel ratio detection means to flow the exhaust gas,
The abnormality detection device, wherein the air-fuel ratio of the exhaust gas detected by the upstream air-fuel ratio detection means is used for abnormality detection of the bypass passage. An abnormality detection method for detecting an abnormality in a gas supply means for supplying a gas containing oxygen to an exhaust path through which exhaust gas flows,
Detecting an air-fuel ratio of the exhaust gas upstream in the exhaust gas flow direction from the gas supply location by the gas supply means in the exhaust path;
Detecting the air-fuel ratio of the exhaust gas downstream of the gas supply location in the exhaust path in the exhaust gas flow direction;
Detecting an abnormality of the gas supply means based on the detection result of the air-fuel ratio of the exhaust gas on the upstream side and the detection result of the air-fuel ratio of the exhaust gas on the downstream side. Anomaly detection method. The abnormality detection method according to claim 4, wherein
The abnormality detection method further comprising the step of detecting an abnormality of the downstream air-fuel ratio detection means for detecting the air-fuel ratio of the exhaust gas on the downstream side. An upstream catalyst provided in an exhaust path and purifying exhaust gas flowing through the exhaust path;
Exhaust gas for controlling an exhaust gas purification device comprising: a downstream side catalyst for purifying the exhaust gas flowing in the exhaust path, provided downstream from the installation position of the upstream catalyst in the exhaust path in the flow direction of the exhaust gas. A purification control device,
Control means for controlling the exhaust gas flowing into the upstream catalyst richly;
A gas supply means for supplying a gas containing oxygen to the richly controlled exhaust gas on the upstream side in the exhaust gas flow direction from the installation position of the upstream catalyst in the exhaust path;
The exhaust gas, which is richly controlled on the upstream side in the flow direction of the exhaust gas with respect to the gas supply position by the gas supply means in the exhaust path, is bypassed by the upstream catalyst to the downstream catalyst. A bypass passage that leads,
Catalyst state detection estimating means for detecting or estimating the state of the upstream catalyst,
When supplying the gas by the gas supply means and controlling the exhaust gas to be rich by the control means, the degree of richness of the controlled exhaust gas is detected or estimated by the catalyst state detection estimating means. Further, the exhaust gas purification control device is set based on the state of the upstream catalyst. The exhaust purification control apparatus according to claim 6,
When the state of the upstream catalyst reaches a predetermined state, the exhaust gas to be controlled is compared with the case where the state of the upstream catalyst does not reach the predetermined state. An exhaust purification control apparatus characterized in that the degree of richness is set to a small value.

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