JP5099150B2 - Exhaust gas purification device abnormality diagnosis device - Google Patents

Description

  The present invention relates to an abnormality diagnosis device that diagnoses whether an abnormality has occurred in a purification function of an exhaust purification device that absorbs and removes a specific component in exhaust gas by bringing exhaust gas of an internal combustion engine into contact with an absorbing liquid.

  Conventionally, as an apparatus for removing NOx in exhaust gas, an apparatus using a NOx storage reduction catalyst and an apparatus using a urea selective reduction catalyst are known. The NOx occlusion reduction catalyst is for reducing the occluded NOx by using HC generated by periodically rich combustion of the internal combustion engine as a reducing agent (see Patent Document 1). The urea selective reduction catalyst selectively reduces NOx in exhaust gas using urea as a reducing agent (see Patent Document 2).

  However, these apparatuses have a disadvantage that the reduction function is not exhibited until the temperature rises to a temperature at which the catalyst is activated (for example, 200 ° C.). Moreover, in recent years, since there is a tendency to introduce low-temperature combustion and exhaust heat recovery technology, the above-mentioned disadvantages are particularly noticeable when starting an internal combustion engine.

  Therefore, the present inventors examined the following apparatus, which is a completely different system from the system of reducing with a catalyst as in Patent Documents 1 and 2. That is, it is a device that holds a liquid (absorbing liquid) that can absorb a specific component (for example, NOx) in the exhaust gas that has come into contact, and absorbs and removes NOx in the exhaust gas by bringing the liquid into contact with the exhaust gas. is there. Specific examples of the absorbing liquid include ionic liquid, alkaline aqueous solution, water and the like. Since such an absorbing liquid can absorb a specific component such as NOx even at room temperature, the conventional drawback that NOx cannot be removed until the catalyst activation temperature is reached can be solved.

  This type of device is also described in Patent Document 3, and the device described in Patent Document 3 stores an absorbing liquid capable of dissolving a specific component in the exhaust gas in a tank, and the exhaust gas is in a bubble state. This is a device that removes harmful substances in exhaust gas by dissolving them in the absorbing liquid by feeding them into the absorbing liquid in the tank.

  However, in the device described in Patent Document 3, it is not assumed that various abnormalities that cause the absorption function to be exhibited are generated, and in order to actually employ this type of device, it is necessary to detect the above abnormalities. It becomes. In addition, as a specific example of the above-mentioned abnormality, when another liquid is mistaken for the absorbing liquid and the apparatus is replenished, when the amount absorbed by the absorbing liquid is in a saturated state reaching the absorbable amount, the absorbing liquid The liquid passage in the apparatus is clogged, the liquid passage in the apparatus is damaged, and the liquid leaks.

JP 2008-82315 A JP 2009-281294 A JP 2000-334259 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to diagnose the presence / absence of an abnormality in an exhaust purification system that absorbs and removes a specific component in exhaust gas using an absorbing liquid. An object of the present invention is to provide an abnormality diagnosis device for an exhaust purification device.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  According to the first aspect of the present invention, when it comes into contact with a specific component in the exhaust gas of the internal combustion engine, it holds an absorbing liquid that absorbs the contacted specific component, and is disposed in the exhaust pipe of the internal combustion engine to contact the absorbing liquid with the exhaust gas. This is applied to an exhaust gas purification device that absorbs and removes the specific component, and an abnormality is detected in the purification function of the exhaust gas purification device based on the state sensor that detects the state of the absorbing liquid and the detection value of the state sensor. And an abnormality determining means for determining whether or not it has occurred.

  For exhaust gas purification devices that use absorption liquid to absorb and remove specific components in exhaust gas, if there is an abnormality in the purification function, the state of the absorption liquid (eg, liquid ph, flow rate, remaining amount, etc.) is abnormal. Is likely to appear. In view of this point, the above-described invention includes a state sensor that detects the state of the absorbing liquid, and determines whether an abnormality has occurred in the purification function based on the detected value. It can be easily realized.

Furthermore, the invention according to claim 1 is provided with a property sensor for detecting a property state of the absorbing liquid as the state sensor, and the abnormality determination unit is configured to discharge the specific component discharged from the internal combustion engine per predetermined time. An emission amount calculating means for calculating an amount; an absorption amount calculating means for calculating an absorption amount of the specific component absorbed by the absorbing liquid per predetermined time based on a property detection value by the property sensor; and the discharge amount calculation. A capability deterioration abnormality determination that determines whether or not the purification capacity is abnormally reduced based on a comparison between the discharge amount per predetermined time calculated by the means and the absorption amount per predetermined time calculated by the absorption amount calculation means And means.

  Since the property state of the absorbing liquid (for example, ph, viscosity, translucency, electrical conductivity, specific gravity, etc. of the liquid) varies depending on the amount of absorption of the specific component, if the property state of the absorbing liquid is detected as in the above invention, The amount of absorption at that time can be calculated, and thus the amount of absorption per predetermined time can also be calculated. Further, since the discharge amount of the specific component changes according to the operation state of the internal combustion engine, the discharge amount per predetermined time can be calculated as in the above invention based on the history of the operation state. Or if the sensor which detects the discharge | emission amount of a specific component is used, the discharge | emission amount per predetermined time can be calculated.

  And, if the purification function is functioning normally, the absorption liquid should absorb the specific component by the amount obtained by multiplying the discharge amount per predetermined time by the predetermined purification rate (normal absorption amount). is there. On the other hand, if the calculated absorption amount per predetermined time is smaller than the normal absorption amount, it can be determined that the purification function is abnormal. Therefore, according to the above-described invention for calculating the discharge amount and the absorption amount per predetermined time and determining whether or not the purification capacity is abnormally reduced based on the comparison of these calculation results, the purification function is abnormal. It can be easily realized whether or not it is present.

According to a second aspect of the present invention, the state sensor includes a liquid amount sensor that detects a liquid amount in a container in which the absorbing liquid leaking from the exhaust purification device is collected, or a flow rate or a remaining amount of the absorbing liquid. The abnormality determining means includes liquid leakage abnormality determining means for determining whether or not there is an abnormality in which the absorbing liquid leaks from the exhaust purification device based on a detection value by the liquid amount sensor. .

  For example, if the liquid passage in the exhaust purification device is not damaged and does not leak, the liquid flow rate when the pump for circulating the liquid is operated should be a predetermined flow rate or more. Alternatively, if the liquid flow rates detected at a plurality of locations in the fluid passage when the pump is operating are greatly different from each other, there is a high possibility that the fluid passage is damaged between the detected locations. . Thus, if the liquid flow rate is detected, it is possible to diagnose the presence or absence of a liquid leakage abnormality based on the detected value. Further, if liquid leakage abnormality occurs, the remaining amount of the absorbing liquid should be greatly reduced in a short time. Further, if a liquid leakage abnormality has occurred, the amount of liquid in the container in which the leaked absorbed liquid is collected should be a predetermined amount or more.

  Therefore, according to the above-described invention, which includes a liquid amount sensor for detecting the flow rate or remaining amount of the absorbing liquid and diagnoses whether or not a liquid leakage abnormality has occurred based on the detected value, whether or not an abnormality has occurred in the purification function. It can be easily realized.

According to a third aspect of the present invention, the exhaust emission control device is attached to an exhaust pipe of the internal combustion engine, contacts an exhaust gas with the exhaust liquid, and branches from the exhaust pipe. A bypass passage that bypasses and distributes the exhaust gas, and a switching valve that switches the flow of the exhaust gas to either the bypass passage or the exhaust gas contactor, and is abnormally determined by the abnormality determining means. If so, the switching valve is operated so that the exhaust gas flows into the bypass passage.

  If the fluid passage in the exhaust gas purification device is damaged and liquid leakage has occurred and it has been judged abnormal by the abnormality judging means, it will be damaged if the exhaust gas flows through the exhaust gas contactor contrary to the above invention. Therefore, there is a high risk of exhaust gas leaking from the leaking part. That is, the exhaust gas of soot discharged from the predetermined part of the exhaust pipe to the atmosphere is released from the damaged part to the atmosphere.

  According to the above-described invention in view of this point, the bypass valve is provided, and when the abnormality is determined, the switching valve is operated so that the exhaust gas flows into the bypass passage, so that the exhaust gas is released from the damaged portion to the atmosphere. The above problems can be avoided.

1 is a diagram showing an exhaust emission control device according to a first embodiment of the present invention. The figure explaining the NOx absorption capability by NOx absorption liquid (NaOH aqueous solution). The schematic diagram explaining definitions, such as absorption ratio (C / (C + D)) of absorption liquid, and maximum absorption amount (C + D). The flowchart which shows the procedure which carries out replacement control of the absorption liquid in 1st Embodiment. The flowchart which shows the procedure which diagnoses abnormality of the purification apparatus in 1st Embodiment. The figure which shows the exhaust gas purification apparatus concerning 2nd Embodiment of this invention. The flowchart which shows the procedure which diagnoses abnormality of the purification apparatus in 2nd Embodiment. The flowchart which shows the procedure which diagnoses abnormality of the purification apparatus in 3rd Embodiment of this invention.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used. In addition, the internal combustion engine to which the exhaust emission control apparatus according to each embodiment is applied is mounted on a vehicle and functions as a travel drive source, and is assumed to be a compression self-ignition type diesel engine.

(First embodiment)
FIG. 1 is a diagram showing an exhaust emission control device and an internal combustion engine 10 according to the present embodiment. First, exhaust gas discharged from the combustion chamber 10a of the internal combustion engine 10 is discharged from a predetermined location behind the vehicle through an exhaust pipe 11 disposed under the vehicle floor. An oxidation catalyst (DOC12) that oxidizes NOx contained in the exhaust gas is attached to the exhaust pipe 11. By this DOC12, NO in the exhaust gas is oxidized to NO2.

  Further, a filter (DPF 13) for collecting particulate matter (PM) in the exhaust is attached to the exhaust pipe 11 downstream of the DOC 12. Then, in order to burn the PM collected by the DPF 13, the injection amount and injection timing from the fuel injection valve 14 are controlled (regeneration processing control) so as to raise the exhaust gas temperature.

  A CO2 removal device 20 that removes CO2 in the exhaust gas is provided on the downstream side of the DPF 13 in the exhaust pipe 11, and NOx in the exhaust gas is removed on the downstream side of the CO2 removal device 20 in the exhaust pipe 11. A NOx removing device 30 is provided. Each of these removal devices 20 and 30 corresponds to an “exhaust gas purification device”. Hereinafter, the configuration of each of the devices 20 and 30 will be described in detail.

<About the CO2 removal device 20>
The CO 2 removal device 20 is mainly configured to include a tank 21, an exhaust gas contactor 22, a circulation pump 23, and a separation / release device 24, which are connected by a circulation pipe 25. A CO 2 absorbing liquid (described in detail later) is stored in the tank 21. This CO 2 absorbing liquid circulates in the circulation path formed by the circulation pipe 25 by the operation of the circulation pump 23. The exhaust gas contactor 22 is attached to the exhaust pipe 11 and functions to bring the circulating CO 2 absorbing liquid into contact with the exhaust gas.

The CO2 absorbing liquid is a liquid that absorbs CO2 by coming into contact with CO2 in the exhaust gas. Specific examples include ionic liquids, alkaline solutions, water (for example, engine cooling water) described in JP-A-2008-296211, and the like. The liquid that selectively absorbs CO2 with little absorption of NOx in the exhaust gas _{(e.g., NaOH, KOH, Na 2 CO} 3, K 2 CO 3, Ca (OH) 2, ethanolamine, etc.) by using the This is preferable because the amount of CO2 absorption can be increased. The CO2 absorbing liquid may be a substance that absorbs CO2 (chemical adsorption) with a chemical change, or a substance that absorbs CO2 (physical adsorption) without a chemical change. The CO2 absorbing liquid may be a gel substance or a slurry substance.

  The exhaust gas contactor 22 includes a holding body 22a that soaks and holds the CO2 absorbing liquid, and a case 22b that houses the holding body 22a therein. The case 22b is connected to the exhaust pipe 11, and exhaust gas circulates in the case 22b. The case 22b is connected to the circulation pipe 25, and the CO2 absorbing liquid that has flowed into the case 22b through the circulation pipe 25 from the inlet of the case 22b is held by the holding body 22a. The holding body 22a is disposed so as to be exposed to the exhaust gas flowing through the case 22b. Therefore, the CO2 absorbing liquid held by the holding body 22a comes into contact with the exhaust gas.

  An inlet valve 22c and an outlet valve 22d are provided at the inlet and outlet of the case 22b. These valves 22c and 22d are electromagnetically driven valves, and their opening and closing operations are controlled by the ECU 15. Therefore, if the ECU 15 opens the outflow valve 22d, the CO2 absorbing liquid in the case 22b can be discharged, and if the ECU15 opens the inflow valve 22c, the CO2 absorbing liquid can flow into the case 22b. it can.

  The inlet is formed in the upper part of the case 22b, and the outlet is formed in the lower part of the case 22b. Therefore, when the outflow valve 22d is operated to open, the discharge can be performed by its own weight even if the circulation pump 23 is not driven. In addition, when the inflow valve 22c is opened while the CO2 absorbing liquid in the case 22b is discharged, the inflow valve 22c can flow by its own weight even if the circulation pump 23 is not driven.

  The separation / release device 24 includes a tank 24a for storing the CO2 absorbing liquid discharged from the exhaust gas contactor 22, and a heater 24b (heating means) provided in the tank 24a. When the CO2 absorbing liquid discharged from the exhaust gas contactor 22 and flowing into the tank 24a is heated by the heater 24b, CO2 absorbed in the CO2 absorbing liquid is separated from the CO2 absorbing liquid.

  The operation of the heater 24b is controlled by the ECU 15. Therefore, if the ECU 15 controls the heater 24b to operate, CO2 separation is promoted, and if the heater 24b is controlled to stop operating, the CO2 separation speed decreases. That is, the ECU 15 functions as a separation control unit that controls the separation speed by controlling the operation of the heater 24b (controlling the degree of heating).

  Here, there is a limit to the amount of CO2 that can be absorbed by the CO2 absorbing liquid per unit amount. In this specification, the state of the CO2 absorbing liquid that has absorbed such a limit amount is referred to as an absorption saturation state. Further, the ratio of the CO2 absorption amount to the amount that the CO2 absorption liquid can absorb CO2 (maximum absorption amount) in a state where the CO2 absorption amount is zero is referred to as an absorption ratio. That is, the absorption ratio in the absorption saturation state is 100%. Then, when CO2 is separated from the CO2 absorbing liquid by the separation / release device 24, the absorption ratio decreases, and the absorbing capacity of the CO2 absorbing liquid increases and returns. The separated CO2 is released to the atmosphere from the discharge port 24c. Then, the CO 2 absorbing liquid in a state where CO 2 is separated and removed by the separation / release device 24 circulates in the order of the tank 21, the CO 2 removal device 20, and the separation / release device 24.

  The operation of the circulation pump 23 is controlled by the ECU 15. In this embodiment, the circulation pump 23 is operated not intermittently but intermittently. That is, the CO2 absorbing liquid is not circulated constantly but is circulated intermittently. The contents of control of the circulation pump 23, the heater 24b, etc. will be described in detail later.

<About the NOx removing device 30>
Next, the configuration of the NOx removing device 30 will be described. The NOx removing device 30 mainly includes a tank 31, an exhaust gas contactor 32, and a circulation pump 33, which are connected by a circulation pipe 35.

  In the tank 31, a supply tank portion 31a that stores unused NOx absorbing liquid (described in detail later) supplied to the exhaust gas contactor 32, and a recovery tank portion 31b that stores the recovered used NOx absorbing liquid. It is divided into and. Thereby, it is avoided that the used NOx absorbing liquid is mixed into the unused NOx absorbing liquid. The NOx absorbing liquid in the supply tank 31 a is supplied to the exhaust gas contactor 32. The NOx absorbing liquid used in the exhaust gas contactor 32 is recovered to the recovery tank portion 31b by operating the circulation pump 33.

  The exhaust gas contactor 32 is attached to the downstream side of the exhaust gas contactor 32 of the CO2 removal device 20 in the exhaust pipe 11 and functions to bring the NOx absorbing liquid into contact with the exhaust gas.

The NOx absorbing liquid is a liquid that absorbs NOx by contacting with NOx in the exhaust gas. Specific examples include ionic liquids, alkaline solutions, water (for example, engine cooling water) described in JP-A-2008-296211, and the like. Further, if a liquid that selectively absorbs NOx without substantially absorbing CO2 in the exhaust gas (for example, FeSO ₄ , Ca (OH) ₂ , H ₂ SO ₄ , K ₂ Cr ₂ O _7, etc.), NOx is used. This is preferable because the amount of absorption can be increased. The NOx absorbing liquid may be a substance that absorbs NOx (chemical adsorption) with a chemical change, or may be a substance that absorbs NOx (physical adsorption) without a chemical change. The NOx absorbing liquid may be a gel substance or a slurry substance.

  FIG. 2 is a test result showing the effect of removing NOx when an aqueous NaOH solution is used as the NOx absorbing liquid. When exhaust gas having a NOx concentration of about 6% is caused to flow into the exhaust gas contactor 22, the exhaust gas contactor 22 It was confirmed that the NOx concentration of the exhaust gas flowing out was reduced to about 1%.

  The exhaust gas contactor 32 includes a holding body 32a that holds the NOx absorbing liquid, and a case 32b that houses the holding body 32a therein. The case 32b is connected to the exhaust pipe 11, and exhaust gas circulates in the case 32b. Further, the case 32b is connected to the circulation pipe 35, and the NOx absorbing liquid that has flowed into the case 32b through the circulation pipe 35 from the inlet of the case 32b is held by the holding body 32a. The holding body 32a is disposed so as to be exposed to the exhaust gas flowing through the case 32b. Therefore, the NOx absorbing liquid held in the holding body 32a comes into contact with the exhaust gas.

  An inlet valve 32c and an outlet valve 32d are provided at the inlet and outlet of the case 32b. These valves 32c and 32d are electromagnetically driven valves, and their opening and closing operations are controlled by the ECU 15. Therefore, if the outflow valve 32d is opened by the ECU 15, the NOx absorbing liquid in the case 32b can be discharged, and if the inflow valve 32c is opened by the ECU 15, the CO2 absorbing liquid can be flowed into the case 32b. it can.

  The inlet is formed in the upper part of the case 32b, and the outlet is formed in the lower part of the case 32b. Therefore, when the outflow valve 32d is opened, it can be discharged by its own weight even if the circulation pump 33 is not driven. In addition, when the inflow valve 32c is opened while the NOx absorbing liquid in the case 32b is discharged, the inflow valve 32c can flow by its own weight even if the circulation pump 33 is not driven.

  A bypass pipe 40 is attached to the exhaust pipe 11, and the bypass pipe 40 forms a bypass passage 40 a that bypasses the exhaust gas contactors 22 and 32 and distributes the exhaust gas. The inlet of the bypass pipe 40 is connected to the upstream side of the exhaust gas contactor 22 in the exhaust pipe 11, and the outlet of the bypass pipe 40 is connected to the downstream side of the exhaust gas contactor 32. The inlet of the bypass passage 40a is opened and closed by a bypass valve 41 (switching valve). The bypass valve 41 is driven by an electric motor, and the operation of the motor is controlled by the ECU 15.

  Here, there is a limit to the amount of NOx that can be absorbed by the NOx absorbing liquid per unit amount. In this specification, the state of the NOx absorbing liquid that has absorbed such a limit amount is referred to as an absorption saturated state. Further, the ratio of the NOx absorption amount to the amount (maximum absorption amount) that the NOx absorbing liquid can absorb NOx in a state where the NOx absorption amount is zero is referred to as an absorption ratio. That is, the absorption ratio in the absorption saturation state is 100%, and the absorption ratio of the unused NOx absorption liquid stored in the supply tank portion 31a is 0%.

  As shown in FIG. 3, when the inflow NOx amount A flowing into the exhaust gas contactor 32 exceeds the exhaust gas regulation value, the NOx is absorbed by the exhaust gas contactor 32 and flows out from the exhaust gas contactor 32. The amount B needs to be less than the regulation value. However, as the absorbed NOx amount C already absorbed by the NOx absorbing liquid in the exhaust gas contactor 32 increases, the absorbable amount D decreases, and when the absorbed NOx amount C reaches the maximum absorbed amount (absorption) When the possible amount D becomes zero), the NOx cannot be absorbed any more, and there is a concern that the outflow NOx amount B exceeds the exhaust gas regulation value.

  Therefore, in the present embodiment, the NOx absorbing liquid whose absorption ratio (C / (C + D)) is higher than a predetermined value in the exhaust gas contactor 32 is recovered to the recovery tank unit 31b by the circulation pump 33. And the NOx absorption liquid whose absorption ratio in the supply tank part 31a is zero is supplied to the exhaust gas contactor 32. The used NOx absorbing liquid recovered in the recovery tank section 31b is extracted from the tank 31 and discharged at a processing facility outside the vehicle. The supply of the new NOx absorbing liquid to the supply tank unit 31a is performed by a vehicle user or a maintenance worker as needed.

  The operation of the circulation pump 33 is controlled by the ECU 15. In this embodiment, the circulation pump 33 is operated not intermittently but intermittently. That is, the NOx absorbing liquid is not constantly circulated, but is intermittently circulated so as to perform the replacement control described below.

  The NOx removing device 30 has a sensor that detects a physical quantity correlated with the absorption ratio of the NOx absorbing liquid. In this embodiment, a ph sensor 32e (state sensor) is used as the sensor, and the ph sensor 32e is attached to the exhaust gas contactor 32. If the ph detected by the ph sensor 32e is equal to or less than a predetermined value (if the acidity is high), the ECU 15 has an absorption ratio of the NOx absorbing liquid in the exhaust gas contactor 32 that is equal to or greater than a predetermined value and has an absorption capacity. Control of replacement of NOx absorption liquid (replacement control) such that the NOx absorption liquid in the exhaust gas contactor 32 is discharged and the NOx absorption liquid in the supply tank portion 31a is supplied into the exhaust gas contactor 32, assuming that it has decreased. ).

  FIG. 4 is a flowchart showing the procedure of the replacement control, and is repeatedly executed by the microcomputer of the ECU 15 at a predetermined cycle (for example, every calculation cycle of the microcomputer or every predetermined crank angle).

  First, in step S10 shown in FIG. 3, it is determined whether or not the absorption ratio of the NOx absorbing liquid in the exhaust gas contactor 22 is equal to or higher than the upper limit ratio. More specifically, the NOx removing device 30 has a sensor that detects a physical quantity correlated with the absorption ratio of the NOx absorbing liquid. In the present embodiment, a ph sensor 32e is used as the sensor, and the ph sensor 32e is attached to the exhaust gas contactor 32. In step S10, if the ph detected by the ph sensor 32e is equal to or less than a predetermined value (if the acidity is high), the absorption ratio of the NOx absorbing liquid in the exhaust gas contactor 32 is equal to or higher than the upper limit ratio (for example, 95%). As a result, the replacement control in the subsequent steps S11 to S17 is performed.

  That is, first, in step S11, the operation of the circulation pump 23 is started. In subsequent step S12, the outflow valve 22d is opened and the inflow valve 22c is kept closed. Thereby, discharge of the NOx absorption liquid in the exhaust gas contactor 32 is started. In the subsequent step S13, it is determined whether or not a predetermined time has elapsed since the outflow valve 32d was opened. The predetermined time is set to a time required for discharging all of the NOx absorbing liquid in the exhaust gas contactor 32.

  When the predetermined time has elapsed (S13: YES), in the subsequent step S14, the outflow valve 22d is closed and the inflow valve 22c is opened. Thereby, the supply of the NOx absorbing liquid into the exhaust gas contactor 32 is started. In subsequent step S15, it is determined whether or not a predetermined time has elapsed since the inflow valve 22c was opened. The predetermined time is set to a time required for the exhaust gas contactor 32 to be supplied in an amount capable of holding the NOx absorbing liquid.

  When the predetermined time has elapsed (S15: YES), the operation of the circulation pump 33 is stopped in the subsequent step S16, and in the subsequent step S17, the closed state of the outflow valve 22d is maintained and the inflow valve 22c is closed. . Thereby, the replacement of the NOx absorbing liquid in the exhaust gas contactor 32 is completed.

  The above is the content of the replacement control for replacing the NOx absorbing liquid in the NOx removing device 30, but the same replacement control is also performed for the CO2 absorbing liquid of the CO2 removing device 20. That is, the replacement control is performed when the absorption ratio of the CO2 absorbing liquid in the exhaust gas contactor 22 is equal to or higher than the upper limit ratio.

  In the replacement control, first, the outflow valve 22d is opened to discharge the CO2 absorbing liquid in the exhaust gas contactor 22. At this time, the exhausted CO 2 absorbing liquid is recovered into the separation / release device 24 by driving the circulation pump 23. When the outflow valve 22d is opened for a predetermined time, it is considered that the discharge of the CO2 absorbing liquid is completed, and the outflow valve 22d is closed and the inflow valve 22c is opened. Thereby, the CO 2 absorbing liquid in the tank 21 flows into the exhaust gas contactor 22. When the inflow valve 22c is opened for a predetermined time, it is considered that the supply replacement of the CO2 absorbing liquid is completed, and the inflow valve 22c is closed. During the replacement control period, the heater 24b is turned on to heat the CO2 absorbing liquid in the separation / release device 24 to separate CO2.

  Next, a method for diagnosing whether or not an abnormality has occurred in the NOx removal function of the NOx removal device 30 will be described. In addition, as a specific example of the above abnormality, when a liquid different from the regular NOx absorbing liquid is mistakenly supplied to the supply tank unit 31a, the NOx absorbing liquid is altered, the tank 31, the exhaust gas contactor 32, The case where the liquid passage in the NOx removal device 30 formed by the circulation pump 33, the circulation pipe 35, etc. is clogged, the case where the liquid passage in the NOx removal device 30 is damaged and the liquid leaks, etc. It is done.

  FIG. 5 is a flowchart showing a procedure for diagnosing the abnormality, and is executed by a microcomputer included in the ECU 15. First, in step S20 (emission amount calculation means), the NOx amount (NOx emission amount p) discharged from the internal combustion engine 10 per predetermined time is calculated based on the transition of the operating state of the internal combustion engine 10 during the predetermined time. Specific examples of the predetermined time include the time from when the ignition switch was previously turned on (or off) to the time when the ignition switch was turned on (or off) this time, the time when the vehicle travels a predetermined distance, For example, the time from immediately after the replacement control is performed to the time immediately before the execution is performed. In short, it is desirable not to perform supply and discharge of the absorbing liquid into the exhaust gas contactor 32 during the predetermined time.

  In the subsequent step S21, the current NOx absorption amount qnow is calculated based on the ph detection value (property detection value) detected by the ph sensor 32e. In subsequent step S22 (absorption amount calculation means), the NOx absorption amount qold calculated from the previous time is subtracted from the NOx absorption amount qnow, thereby calculating the NOx amount (NOx absorption amount q) absorbed from the previous time to the present time. The time from the previous time to the present time is the same time as the predetermined time required for step S20.

  Here, if the NOx removing device 30 functions normally and removes NOx, an amount obtained by multiplying the NOx discharge amount p per predetermined time by a predetermined purification rate r (normal absorption amount p × r). Should be absorbed at least. In view of this point, in the subsequent step S23 (capability decline abnormality determination means), it is determined whether or not the NOx absorption amount q calculated in step S22 is smaller than the normal absorption amount p × r.

  If it is determined that q ≧ p × r (S23: NO), in the next step S24, a normal determination is made that the NOx removing device 30 is functioning normally. On the other hand, if it is determined that q <p × r (S23: YES), in the next step S25, it is determined that the NOx removing device 30 is not functioning normally.

  If an abnormality is determined in this way, the operation of the internal combustion engine 10 is limited in step S26. For example, the crankshaft rotational speed NE is restricted so as not to exceed a predetermined value, or the output torque of the internal combustion engine 10 is restricted so as not to exceed a predetermined value. These restrictions are desirably realized by limiting the fuel injection amount from the fuel injection valve 14.

  If an abnormality is determined in step S25, the operation of the NOx removing device 30 is restricted in step S27. For example, the bypass valve 41 is operated so that the exhaust gas flows into the bypass passage 40a. When the bypass pipe 40 is not provided, the operation of the NOx removing device 30 is limited by prohibiting the operation of the circulation pumps 23 and 33 or prohibiting the replacement control shown in FIG. In addition, it is desirable to provide notifying means (for example, a display lamp 15a) for notifying the vehicle driver that an abnormality has been determined in step S25.

  In the next step S28, the current NOx absorption amount qnow calculated in step S21 is updated by substituting it into the previous value (NOx absorption amount qold), and the series of abnormality diagnosis processing shown in FIG. 5 ends. Note that the diagnosis of whether or not an abnormality has occurred in the CO2 removal function by the CO2 removal device 20 is also the same as the procedure shown in FIG.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The absorption amount q (NOx absorption amount qnow-qold) per predetermined time is calculated using the ph sensors 22e and 32e (state sensors), and the NOx emission amount p (or CO2 emission amount) per predetermined time. And the removal device 20, 30 absorbs and removes NOx or CO 2 when the absorption amount q is significantly lower than the emission amount p (when q <p × r). Diagnose abnormal function. Therefore, it is possible to easily realize whether or not an abnormality has occurred in the purification function of the removal devices 20 and 30.

  (2) When the absorption amount (absorption ratio) of the absorbing liquid changes, a significant change also appears in the ph of the absorbing liquid according to the change. Therefore, according to the present embodiment in which the ph sensors 22e and 32e are provided and the amount of absorption of the absorbing liquid is calculated based on the detected value, the amount of absorption can be calculated with high accuracy, and thus the accuracy of the diagnosis can be improved.

  (3) When the absorption ratio of the absorbing liquid in the exhaust gas contactors 22 and 32 is lower than the upper limit ratio, the supply and discharge of the absorbing liquid to the exhaust gas contactors 22 and 32 are stopped, so that the absorption capacity is still sufficient. It is possible to avoid discharging the absorbing liquid in the exhaust gas from the exhaust gas contactors 22 and 32. Therefore, it is possible to lengthen the use period of the absorbing liquid by delaying the time when the tanks 21 and 31 must be replenished with a new absorbing liquid.

  When the absorption ratio of the absorbing liquid in the exhaust gas contactors 22 and 32 exceeds the upper limit ratio, the absorbing liquid having a high absorption ratio in the exhaust gas contactors 22 and 32 is supplied to the tanks 21 and 31. Since the absorption liquid is replaced with a low absorption ratio, the ratio (absorption rate) of the absorption amount in the exhaust gas contactors 22 and 32 with respect to the NOx and CO2 emission amounts discharged from the internal combustion engine 10 is maintained at a predetermined absorption rate or more. Therefore, it is possible to automatically avoid the amount that passes through the exhaust gas contactor 32 without being absorbed in the exhaust gas exceeding the specified exhaust gas value.

  (4) When performing the replacement control, the exhaust gas contactors 22 and 32 are supplied from the tanks 21 and 31 in an amount capable of holding the absorption liquid, so that the absorption liquid in the exhaust gas contactors 22 and 32 can be replaced without excess or deficiency. it can.

  (5) Since the absorption liquid is supplied from the tanks 21 and 31 after discharging all of the absorption liquid in the exhaust gas contactors 22 and 32 in performing the replacement control, the high absorption ratio discharged from the exhaust gas contactor is high. Mixing of the absorption liquid (or high temperature absorption liquid) and the low absorption ratio absorption liquid (or low temperature absorption liquid) supplied from the tanks 21 and 31 to the exhaust gas contactors 22 and 32 can be suppressed. As a result, in the NOx removing device 30 that is not particularly equipped with the separation / release device 24, it is possible to delay the time when the tank 31 must be replenished with a new NOx absorbing liquid, thereby extending the usage period of the NOx absorbing liquid.

  (6) Here, the NOx absorbing liquid absorbs not only NOx in the exhaust gas but also CO2. Moreover, since the NOx concentration in the exhaust gas of the internal combustion engine 10 is 0.1% or less, the CO2 concentration is several percent to several tens of percent. Therefore, when the CO2 removal device 20 is abolished against the present embodiment, The absorption by the NOx absorbing liquid is dominated by CO2, which causes a problem that NOx cannot be sufficiently absorbed. In this embodiment, the exhaust gas contactor 22 of the CO2 removal device 20 is provided in the exhaust pipe 11 upstream of the exhaust gas contactor 32 of the NOx removal device 30 in this embodiment. The reduced exhaust gas can be sent to the NOx removing device 30. Therefore, the amount of CO2 absorbed by the NOx absorbing liquid can be reduced, and as a result, a sufficient amount of NOx can be absorbed by the NOx absorbing liquid.

  (7) The NOx removal device 30 and the CO2 removal device 20 according to the present embodiment absorb NOx by bringing the NOx absorption liquid into contact with the exhaust gas and absorb CO2 by bringing the CO2 absorption liquid into contact with the exhaust gas. It is. Therefore, since the removal function by the CO2 removal device 20 and the NOx removal device 30 can be exhibited even at room temperature, even in the cold start of the internal combustion engine 10, NOx can be removed.

  (8) Here, in the NOx removal device 30 and the CO2 removal device 20 according to the present embodiment, the exhaust gas contactors 22 and 32 and the tanks 21 and 31 attached to the exhaust pipe 11 are separately configured and circulated. However, if the capacity of the exhaust gas contactors 22 and 32 is equal to that of the tanks 21 and 31, the tanks 21 and 31 can be integrated with the exhaust gas contactors 22 and 32, and the above-described circulation can be made unnecessary. However, when integrated in this way, the exhaust gas contactors 22 and 32 become large, and it becomes extremely difficult to install the exhaust gas contactors 22 and 32 under the floor of the vehicle.

  On the other hand, in this embodiment, since the exhaust gas contactors 22 and 32 and the tanks 21 and 31 are separately configured and circulated, the exhaust gas contact required to be connected to the exhaust pipe 11 located below the floor. The devices 22 and 32 can be reduced in size. Therefore, the exhaust gas contactors 22 and 32 can be easily installed below the floor, and the degree of freedom of the mounting layout can be improved when the NOx removing device 30 and the CO2 removing device 20 are mounted on the vehicle.

  Further, according to the present embodiment in which the exhaust gas contactors 22 and 32 and the tanks 21 and 31 are separately configured and circulated, the capacity of the tanks 21 and 31 is increased for the internal combustion engine 10 having a large displacement. Thus, while the frequency of supplying the absorbing liquid to the exhaust gas contactors 22 and 32 is increased, the exhaust gas contactors 22 and 32 can be shared by the internal combustion engines 10 having different displacements.

  (9) Here, when NOx in the exhaust gas is absorbed by the exhaust gas contactor 32, the absorption rate of NO2 can be higher than that of NO. Therefore, in the present embodiment, since the DOC 12 that oxidizes NO to NO 2 is disposed on the upstream side of the exhaust gas contactor 32, the NOx absorption rate in the exhaust gas contactor 32 can be improved. Moreover, since DPF is arrange | positioned upstream of the exhaust gas contactors 22 and 32, it can suppress that PM in exhaust gas adheres inside the exhaust gas contactors 22 and 32, and clogging arises.

(Second Embodiment)
In the first embodiment, as an example of abnormality, when a liquid other than a normal one is supplied by mistake, the absorption liquid has deteriorated, the liquid passage in the removal devices 20 and 30 is clogged, removal is performed While various abnormalities are assumed, such as when the liquid passages in the devices 20 and 30 are damaged and the liquid leaks, in this embodiment, the liquid leakage abnormality is detected quickly among the above abnormalities. Assumed.

  FIG. 6 shows the removal devices 20 and 30 according to the present embodiment. The first flow rate sensors 25a and 35a and the second flow rate sensors 25b and 35b (liquid level sensors (state sensors)) for detecting the flow rate of the absorbing liquid. Is provided for each of the removing devices 20 and 30. If the flow rate detected by the first flow rate sensors 25a and 35a and the flow rate detected by the second flow rate sensors 25b and 35b are different from each other by a predetermined amount or more, liquid leakage occurs in any of the flow paths. Diagnose that has occurred.

  Alternatively, remaining amount sensors 21 f and 31 f (liquid amount sensors (state sensors)) for detecting the remaining amount of the absorbing liquid in the tanks 21 and 31 are provided for each of the removing devices 20 and 30. If the rate of decrease in the remaining amount detected by the remaining amount sensors 21f and 31f is faster than expected, a liquid leak (especially a liquid leak in the tanks 21 and 31) occurs in any of the distribution paths. Diagnose.

  Alternatively, a recovery container 50 (see the one-dot chain line in FIG. 2) for recovering the absorbing liquid leaking from the distribution path is provided below the removal devices 20 and 30 and the liquid volume for detecting the liquid volume in the recovery container 50 is provided. A sensor 51 is provided. And if the liquid quantity detected by the liquid quantity sensor 51 becomes more than predetermined amount, it will diagnose that the liquid leak has arisen in any of distribution channels, such as the tanks 21 and 31 and waste gas contactors 22 and 32, for example. Note that it is desirable to provide the recovery container 50 so that the opening of the recovery container 50 opens in a range including at least the tanks 21 and 31 and the exhaust gas contactors 22 and 32 when viewed from above.

  FIG. 7 is a flowchart showing a procedure for diagnosing the abnormality, and is executed by a microcomputer included in the ECU 15. First, in step S30, a difference (flow rate difference) between the flow rate detection values by the first flow rate sensors 25a and 35a and the flow rate detection values by the second flow rate sensors 25b and 35b is acquired. At this time, it is desirable to acquire the flow rate difference based on the detected flow rate when the pumps 23 and 33 are driven, such as when the replacement control of FIG. 5 is performed. Alternatively, in step S30, the remaining amount decrease rate based on the detected value change of the remaining amount sensors 21f and 31f is acquired. Alternatively, the liquid amount (recovered liquid amount) in the collection container 50 is acquired by the liquid amount sensor 51 in step S30.

  In subsequent step S31 (liquid leakage abnormality determining means), whether or not the flow rate difference acquired in step S30 is greater than a preset threshold TH1, or the remaining amount reduction rate acquired in step S30 is a preset threshold. It is determined whether or not it is faster than TH2. Alternatively, it is determined whether or not the recovered liquid amount acquired in step S30 is greater than a preset threshold value TH2a.

  If it is determined that the flow rate difference ≦ TH1, or the remaining amount reduction speed ≦ TH2, or the recovered liquid amount ≦ TH2a (S31: NO), the removal devices 20 and 30 function normally in the next step S34. Make a normal judgment. On the other hand, if it is determined that the flow rate difference> TH1 or the remaining amount reduction speed> TH2 or the recovered liquid amount> TH2a (S31: YES), the removal devices 20 and 30 function normally in the next step S35. An abnormality is determined to indicate that it is not.

  When the abnormality is determined in this way, the operation of the internal combustion engine 10 is restricted in step S36, and the operation of the NOx removing device 30 is restricted in step S27. These restrictions are the same as those in steps S26 and S27 in FIG.

  As described above, according to the present embodiment, it is possible to easily realize whether or not a liquid leakage abnormality has occurred in the removal devices 20 and 30.

  In the diagnosis process of FIG. 5, since it is necessary to calculate the NOx emission amount and the NOx absorption amount q per predetermined time, a diagnosis result cannot be obtained unless the predetermined time has elapsed. Moreover, as described above, the predetermined time is a long time (for example, at least several tens of minutes) such as “the time from when the ignition switch was turned on last time to when it was turned on this time”. On the other hand, according to the present embodiment, when a liquid leak occurs, the flow rate difference or the remaining amount decrease rate immediately exceeds the thresholds TH1 and TH2 (for example, several tens of seconds), so that a liquid leak abnormality can be detected early. .

(Third embodiment)
In the first embodiment, it is diagnosed that an abnormality has occurred in the purifying function of the removal devices 20 and 30 when the absorption amount is remarkably small compared to the discharge amount per predetermined time. On the other hand, in this embodiment, when the property of the absorbing liquid has changed greatly within a short time after the absorbing liquid is supplied to the tanks 21 and 31 by a maintenance worker or the like, the purification of the removing devices 20 and 30 is performed. Diagnose abnormal function. The diagnostic method according to the present embodiment is used in the case of a removing device (for example, the CO 2 removing device 20 in FIG. 1) that includes a means for reducing the absorption rate of the absorbing liquid, such as the separation / release device 24, and regenerates and circulates the absorbing liquid. It is valid.

  FIG. 8 is a flowchart showing a procedure for diagnosing the abnormality, and is executed by a microcomputer included in the ECU 15. First, in step S40, it is determined whether or not the internal combustion engine 10 has been operated for a predetermined time (or a predetermined traveling distance) after the absorbing liquid has been supplied to the tanks 21 and 31. If it is determined that the vehicle has been operated for a predetermined time or longer (S40: YES), the series of processes in FIG. 8 is terminated without diagnosing the presence or absence of abnormality. If it is determined that the system has not been operated for a predetermined time or longer (S40: NO), the ph detection value (property detection value) of the absorbed liquid detected by the ph sensor 32e is acquired in the subsequent step S41.

  In a succeeding step S42, it is determined whether or not the ph detection value is lower than a preset threshold value TH3. If there is no abnormality due to alteration of the absorbing liquid, it is possible that ph detection value <TH3 (that is, the absorbable amount is less than the predetermined value) even though the operation time is less than the predetermined time. Absent. Therefore, if it is determined that ph detection value ≧ TH3 (S42: NO), in the next step S44, it is determined that the removal devices 20 and 30 are functioning normally.

  On the other hand, if it is determined that ph detection value <TH3 (S41: YES), it is considered that the absorbable amount has decreased due to the change in the absorption liquid, etc., and in the next step S45, the removal devices 20 and 30 are performed. Judge the abnormality that is not functioning properly.

  When the abnormality is determined in this way, the operation of the internal combustion engine 10 is restricted in step S36, and the operation of the NOx removing device 30 is restricted in step S27. These restrictions are the same as those in steps S26 and S27 in FIG.

  As described above, according to the present embodiment, it is possible to easily realize whether or not a liquid leakage abnormality has occurred in the removal devices 20 and 30. Further, since the calculation of the NOx emission amount p and the calculation of the NOx absorption amount q can be made unnecessary as in the first embodiment, the calculation processing load of the microcomputer can be reduced.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be modified as follows. Moreover, you may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

  In the second embodiment, the liquid leakage abnormality is diagnosed based on the flow rate difference between the first flow rate sensors 25a and 35a and the second flow rate sensors 25b and 35b. , 33 may be diagnosed as having a liquid leakage abnormality when the flow rate detected when operating is lower than a preset threshold value.

  ・ CO2 absorption liquid and NOx absorption liquid may absorb CO2 and NOx (physical absorption) without changing molecular structure, or absorb CO2 and NOx (chemical absorption) while changing molecular structure. )

  In the first embodiment, the circulation pump 23 of the CO2 removing device 20 is intermittently operated to intermittently circulate (replacement control) the CO2 absorbing liquid in the circulation pipe 25. On the other hand, the circulation pump 23 of the CO2 removal device 20 may be always operated to constantly circulate the CO2 absorption liquid in the circulation pipe 25. In this case, it is desirable to variably control the circulation speed according to the absorption ratio of the CO2 absorbing liquid. It is desirable to eliminate the inflow valve 22c and the outflow valve 22d.

  In each of the above embodiments, the exhaust gas and the absorbing liquid are brought into contact with each other by exposing the holding bodies 22a and 32a soaked and holding the absorbing liquid to the exhaust gas. For example, the absorbing liquid is atomized into the exhaust gas. You may comprise so that it may contact by injecting. Alternatively, the absorbing liquid and the exhaust gas may be brought into contact with each other by blowing the exhaust gas into a tank that stores the absorbing liquid.

  In the first embodiment, as shown in FIG. 1, the DOC 12 (oxidation means) that oxidizes NO in the exhaust gas to NO 2 is arranged on the upstream side of the exhaust gas contactor 22. This is advantageous in that the temperature rise of the DOC 12 can be realized in a short time by high-temperature exhaust by disposing the DOC 12 as close as possible to the exhaust port of the internal combustion engine 10 in order to activate the oxidation catalyst. However, when NO is oxidized to NO2, the NOx absorption rate in the exhaust gas contactor 32 can be improved, and at the same time, NOx is easily absorbed by the CO2 absorbing liquid in the exhaust gas contactor 22.

  In view of this point, oxidation means may be disposed in the exhaust pipe 11 on the downstream side of the exhaust gas contactor 22 of the CO2 removal device 20 and on the upstream side of the exhaust gas contactor 32 of the NOx removal device 30. According to this, it can suppress that a CO2 absorption liquid absorbs NOx, and can improve that a NOx absorption liquid absorbs NOx. However, if the oxidizing means is arranged at such a position, the position becomes far from the exhaust port, so that it becomes difficult to activate the oxidation catalyst in a short time by high-temperature exhaust. Therefore, it is desirable to employ an ozone generator or a radical generator instead of the DOC using the oxidation catalyst as the oxidization means having such an arrangement. Or when an oxidation catalyst (DOC) is used, it is desirable to provide an electric heater or a burner for heating the DOC.

  In the separation / release device 24 according to the first embodiment, CO2 is separated by the heater 24b (heating means) for heating the CO2 absorption liquid, but a decompression means for reducing the CO2 absorption liquid is provided instead of the heater 24b. The CO2 absorbing liquid may be configured to separate CO2 by reducing the pressure.

  In the first embodiment, the absorption ratio of the absorbing liquid is detected using the ph sensors 22e and 32e, but the viscosity, translucency, electrical conductivity, and specific gravity of the liquid are also highly correlated with the absorption ratio. The sensors for detecting these physical quantities may be used in place of the ph sensors 22e and 32e. When the absorbing liquid is an ionic liquid, the absorption ratio can be detected using a sensor that detects the ratio of cations (plus ions) and anions (minus ions) in the absorbing liquid.

  In each of the above embodiments, the CO2 removal device 20 is provided on the upstream side of the NOx removal device 30, but the NOx removal device 30 has the ability to absorb a sufficient amount of NOx while absorbing CO2. If so, the CO2 removal device 20 may be abolished.

  In each of the above embodiments, the specific component in the exhaust gas to be absorbed by the absorbing liquid is NOx and CO2, but it may be absorbed and removed for other than these components. For example, when applied to an ignition type gasoline engine, HC in the exhaust gas may be absorbed by the absorbing liquid.

  In each of the above embodiments, the inflow valves 22c and 32c and the outflow valves 22d and 32d may be omitted.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Exhaust pipe, 20 ... CO2 removal device (exhaust gas purification device), 21f, 31f ... Remaining amount sensor (liquid amount sensor (state sensor)), 22, 32 ... Exhaust gas contactor, 22e, 32e ... ph sensor (property sensor (status sensor)), 25a, 25b, 35a, 35b ... flow rate sensor (liquid level sensor (status sensor)), 30 ... NOx removal device (exhaust gas purification device), 40a ... bypass passage, 41 ... bypass Valve (switching valve), 51 ... liquid amount sensor, S20 to S25, S30 to S35, S40 to S45 ... abnormality determining means, S20 ... discharge amount calculating means, S22 ... absorption amount calculating means, S23 ... capability reduction abnormality determining means, S31 ... Liquid leakage abnormality determining means.

Claims (3)

When it comes into contact with a specific component in the exhaust gas of the internal combustion engine, it holds an absorbing liquid that absorbs the specific component that is in contact with it, and is disposed in the exhaust pipe of the internal combustion engine to absorb the specific component by bringing the absorbing liquid into contact with the exhaust gas Applied to the exhaust purification device to remove
A state sensor for detecting the state of the absorbing liquid;
An abnormality determining means for determining whether an abnormality has occurred in a purification function by the exhaust gas purification device based on a detection value of the state sensor ;
A property sensor for detecting the property state of the absorbing liquid is provided as the state sensor,
The abnormality determining means includes
An emission amount calculating means for calculating an emission amount of the specific component discharged from the internal combustion engine per predetermined time;
An absorption amount calculating means for calculating an absorption amount of the specific component absorbed by the absorbing liquid per predetermined time based on a property detection value by the property sensor;
Based on a comparison between the discharge amount per predetermined time calculated by the discharge amount calculation means and the absorption amount per predetermined time calculated by the absorption amount calculation means, it is determined whether or not the purification capacity is abnormally reduced. Ability deterioration abnormality determining means;
An abnormality diagnosis device for an exhaust gas purification device comprising: A liquid amount sensor for detecting the amount of liquid in a container in which the absorbing liquid leaking from the exhaust purification device is collected, or a flow amount sensor or a remaining amount of the absorbing liquid is provided as the state sensor,
The abnormality determination unit includes a liquid leakage abnormality determination unit that determines whether or not an abnormality in which the absorbing liquid leaks from the exhaust purification device has occurred based on a detection value by the liquid amount sensor. Item 10. An exhaust gas diagnosis apparatus abnormality diagnosis device according to Item 1 . The exhaust purification device includes:
An exhaust gas contactor attached to an exhaust pipe of the internal combustion engine, for contacting the absorbing liquid with exhaust gas;
A bypass passage branched from the exhaust pipe and bypassing the exhaust gas contactor to distribute the exhaust gas;
A switching valve for switching the flow of exhaust gas to either the bypass passage or the exhaust gas contactor;
It is configured with
3. The exhaust emission control device according to claim 1, wherein when the abnormality is determined by the abnormality determination unit, the switching valve is operated so that the exhaust gas flows into the bypass passage. 4. Abnormality diagnosis device.

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