JP2019070326A - Exhaust emission control device for internal combustion engine and abnormality determination method for exhaust emission control device for internal combustion engine - Google Patents

Abstract

To provide an exhaust emission control device for an internal combustion engine capable of determining abnormality of each of a diffusion member and a DPF by using one pressure difference detection means in the exhaust emission control device for the internal combustion engine including a diffusion member for mixing and diffusing a reducing agent in exhaust gas, a selective reduction catalyst and the DPF, and an abnormality determination method for the exhaust emission control device for the internal combustion engine.SOLUTION: An exhaust emission control device for an internal combustion engine includes: a particulate collection filter 42A; a selective reduction catalyst 42B; an addition valve 21 for spraying a reducing agent toward a diffusion member; the diffusion member 48 for diffusing the sprayed reducing agent in exhaust gas; pressure difference detection means 38 for detecting a detection target pressure difference that is a pressure difference between a pressure of the exhaust gas upstream of a detection target 49A including the particulate collection filter and the diffusion member and a pressure of the exhaust gas downstream of the detection target; and an abnormality determination device 50 capable of detecting an operating state of the internal combustion engine and of determining each of abnormality of the particulate collection filter and abnormality of the diffusion member on the basis of the detected operating state and the detection target pressure difference detected by the pressure difference detection means.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust gas control apparatus for an internal combustion engine and an abnormality determination method for an exhaust gas control apparatus for an internal combustion engine.

  For example, Patent Document 1 discloses a selective reduction catalyst disposed in an exhaust path of an internal combustion engine to reduce NOx in the exhaust, and a urea reducing agent disposed in an exhaust path upstream of the selective reduction catalyst to supply a urea reducing agent An exhaust purification system of an engine is disclosed which has a supply means and a mixing member disposed in an exhaust path near the urea reductant supply means to promote mixing of the supplied urea reductant and the exhaust. In addition, differential pressure detection means for detecting the differential pressure between the upstream and downstream of the mixing member is provided, and when the detected differential pressure becomes equal to or higher than a predetermined value, the temperature of the exhaust is raised to perform mixing. The crystal of the compound adhering to the member is removed by melting.

JP, 2009-24655, A

  In Patent Document 1, a first differential pressure sensor for detecting a differential pressure immediately upstream and downstream of the DPF for estimating the amount of fine particles deposited on the DPF, a mixing member (hereinafter, a mixing member as a diffusion member) A second differential pressure sensor is required to detect the differential pressure immediately upstream and downstream of the diffusion member to determine the abnormality that the opening of the diffusion member is blocked by adhesion of the compound crystal to the And the structure of the exhaust purification device is complicated. Further, in an exhaust gas purification apparatus for an internal combustion engine, it is also required to determine the presence or absence of an abnormality such as cracking or clogging in a DPF that collects particulates in exhaust gas.

  The present invention has been made in view of these points, and it is one difference in an exhaust gas purification apparatus for an internal combustion engine having a diffusion member for mixing and diffusing a reducing agent into exhaust gas, a selective reduction catalyst, and a DPF. It is an object of the present invention to provide an exhaust gas control apparatus for an internal combustion engine and an abnormality determination method for an exhaust gas control apparatus for an internal combustion engine, which are capable of determining the respective abnormalities of the diffusion member and the DPF by the pressure detection means.

  In order to solve the above problems, according to a first aspect of the present invention, there is provided a particulate collection filter disposed in an exhaust path of an internal combustion engine and configured to collect particulate matter in exhaust gas, and selective reduction disposed in the exhaust path. A catalyst, an addition valve which is disposed upstream of the exhaust gas than the selective reduction catalyst in the exhaust gas path and sprays a reducing agent toward the diffusion member, and upstream or downstream of the exhaust gas path in the vicinity of the addition valve In the exhaust path which is disposed upstream of the detection target including the diffusion member disposed on the side to diffuse the reducing agent sprayed from the addition valve into the exhaust, the particulate collection filter, and the diffusion member Differential pressure detection means for detecting a differential pressure of a detection target portion which is a differential pressure between the pressure of the exhaust gas and the pressure of the exhaust gas in the exhaust path downstream of the detection target portion; With being detectable Abnormality determination capable of determining each of the abnormality of the particulate matter collection filter and the abnormality of the diffusion member based on the detected operating condition and the detection target portion differential pressure detected by the differential pressure detection means And an apparatus for exhaust gas purification of an internal combustion engine.

  A second aspect of the present invention is the exhaust gas purification apparatus for an internal combustion engine according to the first aspect, wherein the abnormality determination device is configured to detect a state in which the operation state satisfies a predetermined operation state. It is an exhaust gas purification device of an internal combustion engine which judges each of an abnormality of the particulate collection filter and an abnormality of the diffusion member based on the differential pressure of the detection target portion with respect to an exhaust flow velocity which is an exhaust flow velocity.

  A third aspect of the present invention is the exhaust gas control apparatus for an internal combustion engine according to the second aspect, wherein the abnormality determination device is configured to control the exhaust flow velocity when the operating state satisfies the predetermined operating state. It is determined that the diffusion member is abnormal when the target differential pressure is a differential pressure greater than the upper limit characteristic for which the upper limit differential pressure with respect to the exhaust flow velocity is set, and the detection target differential with respect to the exhaust flow velocity It is an exhaust gas purification device of an internal combustion engine which judges that the particulate matter collection filter is abnormal, when pressure is a differential pressure whose lower limit differential pressure to the exhaust gas flow velocity is smaller than a set lower limit characteristic.

  A fourth aspect of the present invention is the exhaust gas control apparatus for an internal combustion engine according to the third aspect, wherein the abnormality determination device is configured to control the exhaust flow velocity when the operating state satisfies the predetermined operating state. When the detection target differential pressure is equal to or lower than the upper limit characteristic and equal to or higher than the lower limit characteristic, each of the detection target differential pressures is detected with respect to a plurality of the exhaust flow velocities, When the curvature of the exhaust flow velocity / the detection target differential pressure characteristic connecting the detection target portion differential pressure is a curvature larger than the curvature of the evaluation characteristic set in advance, both the particle collection filter and the diffusion member are It is an exhaust gas purification apparatus for an internal combustion engine that is determined to be abnormal.

  According to a fifth aspect of the present invention, there is provided a particulate collection filter disposed in an exhaust path of an internal combustion engine for trapping particulate matter in exhaust, a selective reduction catalyst disposed in the exhaust path, and the exhaust path. An addition valve which is disposed upstream of the exhaust gas than the selective reduction catalyst and which sprays a reducing agent toward the diffusion member, and which is disposed upstream or downstream of the addition valve near the addition valve in the exhaust passage. And a diffusion member for diffusing the reducing agent sprayed from a valve into the exhaust gas, wherein the abnormality in the exhaust gas purification device of the internal combustion engine determines the abnormality in the particulate matter collection filter and the abnormality in the diffusion member. A determination method, comprising: a pressure of exhaust gas in the exhaust path upstream of a detection target portion including the particulate collection filter and the diffusion member; and a pressure in the exhaust path downstream of the detection target portion The operating condition for detecting the operating condition of the internal combustion engine by the abnormality determining device using the differential pressure detecting means for detecting the differential pressure of the detection target which is the differential pressure of air pressure and the abnormality determining device A detection step; a differential pressure detection step for detecting the target differential pressure according to the detected operating condition in the abnormality determination device; and the detection object according to the operating condition in the abnormality determination device An abnormality determination method for an exhaust gas purification apparatus for an internal combustion engine, comprising: an abnormality determination step of determining each of an abnormality of the particulate matter collection filter and an abnormality of the diffusion member based on a partial pressure difference.

  A sixth aspect of the present invention is the method for determining abnormality of an exhaust gas purification apparatus for an internal combustion engine according to the fifth aspect, wherein the operating state detected in the operating state detecting step satisfies a predetermined operating state. In the differential pressure detection step, the differential pressure of the detection target is detected together with the exhaust flow velocity which is the flow velocity of the exhaust in the exhaust passage, and in the abnormality determination step, the differential pressure of the detection target relative to the exhaust flow velocity is detected. It is an abnormality determination method of the exhaust gas purification device of an internal combustion engine which determines each of an abnormality of the particulate collection filter and an abnormality of the diffusion member based on it.

  A seventh invention of the present invention is the method for determining abnormality of an exhaust gas purification apparatus for an internal combustion engine according to the sixth invention, wherein in the abnormality determination step, the detection target portion differential pressure with respect to the exhaust gas flow velocity is It is determined that the diffusion member is abnormal when the upper limit differential pressure with respect to the exhaust flow velocity is larger than the set upper limit characteristic, and the detection target differential pressure with respect to the exhaust flow velocity is the lower limit difference with respect to the exhaust flow velocity. When the differential pressure is smaller than a set lower limit characteristic, the particulate matter collection filter is determined to be abnormal.

  An eighth aspect of the present invention is the method for determining abnormality in an exhaust gas purification apparatus for an internal combustion engine according to the seventh aspect, wherein in the abnormality determining step, the detection target portion differential pressure with respect to the exhaust gas flow velocity is the upper limit. In the case where it is not more than the characteristic and is not less than the lower limit characteristic, the exhaust pressure obtained by detecting the differential pressure of each detection target for a plurality of the exhaust flow velocity, and connecting the differential pressure of each detection target to the respective exhaust flow velocity An internal combustion engine that determines that both the particulate collection filter and the diffusion member are abnormal when the curvature of the flow velocity / detection part differential pressure characteristic is a curvature larger than the curvature of a preset evaluation characteristic. And a method of determining abnormality of the exhaust gas control apparatus.

  According to the first invention or the fifth invention, the pressure in the exhaust path on the upstream side of the detection target portion including the particulate collection filter and the diffusion member, and the pressure in the exhaust path on the downstream side of the detection target portion And one differential pressure detection means for detecting the differential pressure. Then, based on the detection target portion differential pressure detected by the differential pressure detection means, the abnormality determination device determines each of the abnormality of the particulate collection filter and the abnormality of the diffusion member. Thus, an exhaust gas control apparatus for an internal combustion engine and an abnormality determination method for an exhaust gas control apparatus for an internal combustion engine can be provided, by which one differential pressure detection means can determine an abnormality in each of the diffusion member and the DPF. Can.

  According to the second invention or the sixth invention, it is possible to appropriately determine each of the abnormality of the particulate matter collection filter and the abnormality of the diffusion member based on the detection target portion differential pressure with respect to the exhaust gas flow velocity.

  According to the third invention or the seventh invention, when the differential pressure to be detected with respect to the exhaust flow velocity is larger than the upper limit characteristic, it is determined that the diffusion member is abnormal, and the differential pressure to be detected relative to the exhaust flow velocity is If the differential pressure is smaller than the lower limit characteristic, it is determined that the particulate matter collection filter is abnormal. Thereby, each differential pressure of the diffusion member and the DPF can be easily and appropriately determined by one differential pressure detection means.

  According to the fourth invention or the eighth invention, even if the differential pressure to be detected relative to the exhaust gas flow velocity is a differential pressure smaller than the upper limit characteristic and a differential pressure larger than the lower limit characteristic, It is possible to appropriately determine the state in which both the abnormality of the diffusion member and the abnormality of the particulate collection filter are occurring.

It is a figure explaining an example of composition of a 1st embodiment to which an exhaust gas purification device of an internal-combustion engine of the present invention is applied. It is a figure explaining an example of composition of a 2nd embodiment to which an exhaust gas purification device of an internal-combustion engine of the present invention is applied. It is a flowchart explaining the example of the processing procedure of the abnormality determination apparatus in the 1st and 2nd embodiment. It is a figure explaining the example of an upper limit characteristic and a lower limit characteristic. It is a figure explaining the example of evaluation characteristic. It is a figure explaining the example of the procedure which calculates | requires a curvature radius from detected (exhaust flow velocity, detection object part differential pressure).

[Configuration of formation of the first embodiment applying an exhaust gas purification apparatus for an internal combustion engine (FIG. 1)]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of the configuration of an internal combustion engine in the first embodiment, and the internal combustion engine 10 is, for example, a diesel engine. In the following description, DPF (Diesel Particulate Filter) corresponds to a particulate collection filter, and SCR corresponds to a selective reduction catalyst.

  In the exhaust passage 12 of the internal combustion engine 10, from the upstream side, the first oxidation catalyst 41, the diffusion member 48, the SCRF 42 (a catalyst that integrates the function of the DPF 42A and the function of the selective reduction catalyst 42B (SCR)), the second oxidation catalyst 46 , Are provided sequentially. Further, on the upstream side of the first oxidation catalyst 41, a fuel injection valve 28 for injecting a fuel for raising the exhaust gas temperature at the time of regenerating the DPF on which the particulates are accumulated (combusting and burning the particulates), exhaust temperature detection Means 36A (for example, an exhaust temperature sensor) are provided. Further, on the downstream side of the first oxidation catalyst 41 and on the upstream side of the SCRF 42, an addition valve 21 for spraying a reducing agent (in this case, urea water) toward the diffusion member 48, the sprayed reducing agent in the exhaust gas A diffusion member 48 for mixing and diffusing, and an exhaust temperature detection means 36B (for example, an exhaust temperature sensor) are provided. The addition valve 21 is disposed upstream or downstream in the vicinity of the diffusion member 48. Further, an exhaust temperature detection means 36C (for example, an exhaust temperature sensor) is provided downstream of the SCRF 42 and upstream of the second oxidation catalyst 46.

  The pressure of the exhaust gas in the exhaust gas passage 12 upstream of the detection subject 49A including the SCRF 42 having the function of the DPF and the diffusion member 48 and the exhaust gas in the exhaust gas passage 12 downstream of the detection subject 49A A differential pressure detection means 38 is provided which detects a differential pressure of a detection target which is a differential pressure between the pressure and the pressure. The upstream pipe 38A of the differential pressure detection means 38 is connected to the exhaust path 12 on the upstream side (direct upstream) of the diffusion member 48. The downstream pipe 38 B of the differential pressure detection means 38 is connected to the exhaust path 12 on the downstream side (direct downstream) of the SCRF 42.

  The first oxidation catalyst 41 is a catalyst for rendering harmless hydrocarbon (HC) and carbon monoxide (CO), and the DPF 42A is a filter for collecting particulate matter in the exhaust gas. The selective reduction catalyst 42B is a catalyst that renders nitrogen oxides (NOx) harmless using a reducing agent (in this case, urea water) which is injected from the addition valve 21 and diffused by the diffusion member 48. The second oxidation catalyst 46 is a catalyst that harms the reducing agent left unused in the reaction by the selective reduction catalyst 42B.

  The reducing agent is supplied to the adding valve 21 from the reducing agent tank 22 through the discharge pipe H2. The reducing agent tank 22 is provided with a pressure detection means 26 (for example, a pressure sensor) and a pump 23 via a pipe H1. For example, the control device 50 controls the pump 23 so that the pressure in the reducing agent tank 22 becomes a predetermined pressure based on the detection signal from the pressure detecting means 26, and the hydraulic pressure of the reducing agent supplied to the addition valve 21. Maintain a constant pressure.

  The control device 50 can output a control signal to each of the addition valve 21 and the pump 23 to control each of them. The control device 50 can adjust the amount of supply of the reducing agent by controlling the opening degree of the addition valve 21, the energization time, and the like.

  In the control device 50 (corresponding to an abnormality determination device), a detection signal of the intake air flow rate detection means 31 provided in the intake passage 11, a detection signal of the NOx detection means 32, a detection signal of the accelerator opening degree detection means 33, rotation detection Each of the detection signals of the means 34 is input. The control device 50 also receives the detection signals of the exhaust gas temperature detection means 36A, 36B, 36C and the detection signal of the differential pressure detection means 38 described above. The control device 50 can detect the operating state of the internal combustion engine 10 based on the signals from these detection means.

  The intake air flow rate detecting means 31 (for example, a flow rate sensor) is provided in the intake passage 11 of the internal combustion engine 10 and outputs a detection signal according to the flow rate of the air taken in by the internal combustion engine 10. The NOx detection means 32 (for example, a NOx sensor) is provided in the exhaust passage 12 of the internal combustion engine 10 and outputs a detection signal corresponding to NOx in the exhaust gas of the internal combustion engine 10. The accelerator opening degree detecting means 33 (for example, an accelerator opening degree sensor) outputs a detection signal according to the opening degree of the accelerator operated by the driver (that is, the load required by the driver). The rotation detection means 34 (for example, a rotation sensor) outputs a detection signal corresponding to the rotation of the crankshaft of the internal combustion engine 10, for example. Each of the exhaust temperature detection means 36A, 36B, 36C outputs a detection signal according to the temperature of the exhaust gas in the exhaust passage 12 in which it is disposed.

  The controller 50 determines the amount of reducing agent to be injected from the addition valve 21 based on the detected intake air flow rate, NOx, required load, and rotational speed of the internal combustion engine, and controls the pump 23 and the addition valve 21. The amount of reducing agent obtained is injected from the addition valve 21. Further, the control device 50 injects fuel from the injector (not shown) to the internal combustion engine 10 based on the operating state of the internal combustion engine 10 obtained based on detection signals from the respective detection means, and injects fuel from the fuel injection valve 28 Do. The control device 50 has a storage device.

[Configuration of formation of second embodiment applying exhaust gas purification apparatus for internal combustion engine (FIG. 2)]
FIG. 2 shows an example of the configuration of an internal combustion engine in the second embodiment. In the second embodiment shown in FIG. 2, the difference is that the SCRF 42 of the first embodiment shown in FIG. 1 is separated into the DPF 43 and the selective reduction catalyst 44, and the difference detected by the differential pressure detection means 38 The position of pressure is different. The differences from the first embodiment will be mainly described below. The same reference numerals as those in FIG. 1 denote the same components as those in FIG.

  In the exhaust passage 12 of the internal combustion engine 10, a first oxidation catalyst 41, a DPF 43, a diffusion member 48, a selective reduction catalyst 44, and a second oxidation catalyst 46 are sequentially provided from the upstream side. Exhaust gas temperature detection means 36 B is provided downstream of the first oxidation catalyst 41 and upstream of the DPF 43. Further, on the downstream side of the DPF 43 and on the upstream side of the selective reduction catalyst 44, a diffusion member 48, an addition valve 21, and an exhaust temperature detection means 36C are provided.

  Then, the difference between the pressure of the exhaust in the exhaust passage 12 on the upstream side of the detection target 49B including the DPF 43 and the diffusion member 48 and the pressure of the exhaust in the exhaust passage 12 on the downstream of the detection target 49B. A differential pressure detection means 38 is provided for detecting a differential pressure to be detected which is a pressure. The upstream pipe 38A of the differential pressure detection means 38 is connected to the exhaust path 12 on the upstream side (direct upstream) of the DPF 43. The downstream pipe 38 B of the differential pressure detection means 38 is connected to the exhaust path 12 on the downstream side (direct downstream) of the diffusion member 48.

  The DPF 43 is a filter that collects particulate matter in the exhaust gas. The selective reduction catalyst 42B is a catalyst that renders nitrogen oxides (NOx) harmless using a reducing agent (in this case, urea water) which is injected from the addition valve 21 and diffused by the diffusion member 48.

[Processing procedure of control device 50 (abnormality judging device) (FIG. 3)]
Next, the procedure of determining each of the abnormality of the DPF 42A (43) and the abnormality of the diffusion member 48 by the control device 50 (the abnormality determination device) will be described using the flowchart shown in FIG. The processing procedure shown in FIG. 3 is common to the first embodiment (FIG. 1) and the second embodiment (FIG. 2). Further, the abnormality of the DPF is mainly a crack of the DPF, and the abnormality of the diffusion member is a clogging mainly due to a crystal or the like attached to the diffusion member. The control device 50 activates the process shown in FIG. 3 at predetermined time intervals (for example, several ms to several hundreds ms), for example, and when activated, advances the process to step S110.

  In step S110, the control device 50 detects the operating state of the internal combustion engine based on the detection signals and the like from the various detection means described above, and proceeds to step S120. Step S110 corresponds to an operating condition detecting step of detecting an operating condition of the internal combustion engine.

  In step S120, control device 50 determines whether or not it is within the predetermined period after completion of the DPF regeneration process based on the detected operating state, and if within the predetermined period (Yes), it is determined in step S125. The process proceeds, and if it is not within the predetermined period (No), the process proceeds to step S210. The DPF regeneration process is a process that is not shown, and the control device 50 determines that the DPF 42A (43) has collected particulate matter of a predetermined amount or more, and the fuel injection valve 28 (FIG. (See FIG. 2) to inject fuel to forcibly raise the temperature of the exhaust gas to burn and incinerate particulate matter in the DPF. By performing the DPF regeneration process, it is possible to burn and incinerate the particulate matter in the DPF, and it is also possible to melt and remove crystals and the like attached to the diffusion member. Therefore, if the DPF regeneration process is normally performed, the pressure loss due to the DPF 42A (43) is reduced, and the pressure loss due to the diffusion member 48 is also reduced. Then, after completion of the DPF regeneration process, within the predetermined period (for example, within several tens of minutes), almost no particulate matter deposits on the DPF 42A (43) (the deposition amount is almost zero), and diffusion Almost no crystal or the like is attached to the member 48 (the attached amount is substantially zero).

  When the process proceeds to step S125, the control device 50 calculates the exhaust gas flow velocity, and proceeds to step S130. The control device 50 is based on, for example, the amount of intake air detected by the intake air flow rate detecting means 31, the rotational speed of the internal combustion engine detected by the rotation detecting means 34, the fuel injection amount from the injector, etc. The flow velocity of the exhaust gas from can be determined. The method of determining the exhaust flow velocity is not particularly limited.

  At step S130, control device 50 obtains (determines) a differential pressure to be detected which is a differential pressure of detection target portion 49A (49B) based on the detection signal from differential pressure detection means 38, and proceeds to step S135. .

  In step S135, the control device 50 stores the differential pressure (detection target portion differential pressure) acquired in step S130 in the storage device together with the exhaust flow velocity obtained in step S125, and proceeds to step S140. Specifically, the control device 50 stores (exhaust flow velocity, differential pressure) in one set in the storage device. Therefore, the control device 50 stores a plurality of (exhaust flow velocity, differential pressure) within a predetermined period (from step S120) after the completion of the DPF regeneration process. Steps S125 to S135 correspond to a differential pressure detection step of detecting a differential pressure to be detected according to the operating state of the internal combustion engine.

  In step S140, the control device 50 sets a detected flag indicating that (exhaust flow velocity, differential pressure) has been stored, and ends the process.

  If the process proceeds to step S210, the control device 50 determines whether the detected flag is ON (set state). If the detected flag is ON (Yes), the process proceeds to step S215, and the detected flag is If not ON (No), the process ends.

  When the process proceeds to step S215, the control device 50 clears the detected flag (turns off) and proceeds to step S220. Therefore, the process after step S220 is performed only once after passing a predetermined period after completion of the DPF regeneration process in steps S120, S140, S210, and S215 (after storing a plurality of (exhaust flow velocity, differential pressure)). To be executed.

  In step S220, the control device 50 sets the differential pressure with respect to the exhaust flow velocity at all of the plurality of (exhaust flow velocity, differential pressure) stored in the storage device or extracted (exhaust flow velocity, differential pressure) based on predetermined conditions. With respect to the upper limit characteristic shown in FIG. 4, it is determined whether or not the differential pressure is high (whether or not it belongs to the region A in FIG. 4). If all or the extracted (exhaust flow velocity, differential pressure) is a differential pressure higher than the upper limit characteristic (belongs to the region A in FIG. 4) (Yes), the control device 50 proceeds to step S250 and the upper limit If it is not the differential pressure higher than the characteristic (No), the process proceeds to step S320. Note that the predetermined condition at the time of extraction is, for example, a condition appropriately set such that the exhaust flow velocity is equal to or higher than the first flow velocity threshold and equal to or lower than the second flow velocity threshold. Not limited The “upper limit characteristic” in FIG. 4 (exhaust flow velocity / (upper limit) differential pressure characteristic in which the upper limit differential pressure to the exhaust flow velocity is set) is stored in advance in the storage device. Further, the description of each characteristic of FIG. 4 will be described later.

  When the process proceeds to step S250, the control device 50 determines that the diffusion member is abnormal and the DPF is normal, and ends the process.

  When the process proceeds to step S320, the control device 50 extracts the exhaust flow velocity at (exhaust flow velocity, differential pressure) extracted based on all of a plurality of (exhaust flow velocity, differential pressure) stored in the storage device or a predetermined condition. It is determined whether or not the differential pressure with respect to the lower limit characteristic shown in FIG. 4 is a lower differential pressure (whether or not it belongs to the region B in FIG. 4). If all or extracted (exhaust flow velocity, differential pressure) is a differential pressure on the lower side than the lower limit characteristic (belongs to region B in FIG. 4) (Yes), the control device 50 proceeds to step S350 and the lower limit If it is not the differential pressure lower than the characteristic (No), the process proceeds to step S420. In addition, the predetermined condition at the time of extraction is, for example, a condition appropriately set such that the exhaust flow velocity is equal to or higher than the third flow velocity threshold and equal to or lower than the fourth flow velocity threshold, and specific contents of the predetermined condition are particularly limited. do not do. The “lower limit characteristic” in FIG. 4 (exhaust flow velocity / (lower limit) differential pressure characteristic at which the lower limit differential pressure to the exhaust flow velocity is set) is stored in advance in the storage device.

  When the process proceeds to step S350, the control device 50 determines that the DPF is abnormal and the diffusion member is normal, and ends the process.

[Exhaust flow velocity / differential pressure characteristics (Fig. 4)]
FIG. 4 shows an example of “normal standard characteristics”, “upper limit characteristics”, and “lower limit characteristics” in a coordinate system in which the horizontal axis represents exhaust flow velocity and the vertical axis represents differential pressure. The “normal normal characteristics” refers to normal DPF (DPF in which fine particles are burned and burned and particulate deposition is almost zero after completion of DPF regeneration treatment), normal diffusion member (crystals, etc. are melted and attached) The relationship between the flow velocity of the exhaust gas and the pressure difference with respect to the diffusion member in a state in which the crystal and the like are substantially absent is a characteristic obtained by experiment or the like. Even if the DPF regeneration process is completed, if, for example, crystals or the like attached to the diffusion member remain, the diffusion member is clogged and the pressure loss is increased. The characteristic changes to the "characteristic" side. An area A shown in FIG. 4 is an area where a pressure loss due to clogging of the diffusion member can not be tolerated, and it is determined in step S220 whether or not this state is present. In addition, even if DPF regeneration processing is completed, for example, if cracking occurs in the DPF, the exhaust leaks from the cracking of the DPF and the differential pressure becomes smaller, so from the “normal characteristics at normal time” to “lower limit characteristics The characteristic changes to the "" side. The region B shown in FIG. 4 is a region where a crack is generated in the DPF and the leak of the exhaust gas is apparently generated, and it is determined in step S320 whether the state is this state or not.

  In [Exhaust flow velocity / differential pressure characteristics] shown in FIG. 4, “area A” is a state in which the differential pressure with respect to the exhaust flow velocity increases due to clogging of the diffusion member (DPF is normal), and the diffusion member is abnormal , DPF is an area determined to be normal (step S250). “Area B” is a state in which the differential pressure with respect to the exhaust flow velocity decreases due to cracking of the DPF (the diffusion member is in a normal state), the DPF is abnormal, and the diffusion member is determined to be normal (step S350) It is.

  In FIG. 4, “region C” sandwiched between “region A” and “region B” does not necessarily mean that both the DPF and the diffusion member are normal. For example, when both the clogging of the diffusion member and the cracking of the DPF occur, the characteristics in the “region C” may be obtained. That is, when the detected (exhaust flow velocity, differential pressure) belongs to the “region C”, it is considered that (DPF, diffusion member) is either (normal, normal) or (abnormal, abnormal).

  Therefore, if the detected (exhaust flow velocity, differential pressure) belongs to the “region C”, it is necessary to distinguish whether (DPF, diffusion member) is (normal, normal) or (abnormal, abnormal) . In the case where both the clogging of the diffusion member and the cracking of the DPF occur (in the case of (abnormal or abnormal)), the inventor is in the “region C” as shown in “evaluation characteristics” of FIG. 5. However, it has been found that the curvature of the "evaluation characteristic" is larger than the curvature of the "normal standard characteristics (in the case of (normal, normal))". "Evaluation characteristics" in FIG. 5 shows an example of characteristics when (DPF, diffusion member) is (abnormal, abnormal), and "normal characteristics at normal time" are (DPF, diffusion member) (normal) , Normal) is shown. Then, the inventor found that the curvature becomes larger (the curvature radius becomes smaller) as the degree of clogging of the diffusion member and cracking of the DPF becomes larger. The "evaluation characteristics" shown in FIG. 5 are in a state in which clogging of the diffusion member and cracking of the DPF occur, and when the curvature is larger than the curvature of the "evaluation characteristics" (or the curvature of the "evaluation characteristics") When the radius of curvature is smaller than the radius), it can be determined that both the clogging of the diffusion member and the cracking of the DPF occur. The curvature radius (or curvature) of the "evaluation characteristic" is stored in advance in the storage device. Further, in FIG. 5, the curvature center Cs indicates the center of the curvature circle of the “evaluation characteristic”, and the curvature radius Rs indicates the radius of the curvature circle of the “evaluation characteristic”. For example, to determine whether the curvature of the detected characteristic is a curvature larger than the curvature of the "evaluation characteristic", the curvature radius of the detected characteristic is smaller than the curvature radius Rs of the "evaluation characteristic". It may be determined whether or not it is a radius.

  Here, an example of a procedure for obtaining the curvature radius R1 of the detection characteristics (corresponding to the exhaust flow velocity and the detection target differential pressure characteristic) based on the plurality of (exhaust flow velocity and differential pressure) detected will be described using FIG. For example, the exhaust flow velocity Va and the exhaust flow velocity Vb (Va <Vb) are determined, and the exhaust flow velocity is in the range α below the exhaust flow velocity Va, the region β above the exhaust flow velocity Va and below the exhaust flow velocity Vb, the region γ above the exhaust flow velocity Vb Divide into three areas. Then, among a plurality of (exhaust flow velocity, differential pressure) stored, it corresponds to the region α (exhaust flow velocity, differential pressure), corresponds to the region β (exhaust velocity, differential pressure), corresponds to the region γ (Exhaust flow velocity, differential pressure) is extracted. In the example of FIG. 6, Q1 (V1, P1) is extracted as (exhaust flow velocity, differential pressure) corresponding to region α, and Q2 (V2, P2) is extracted as (exhaust velocity, differential pressure) corresponding to region β An example in which Q3 (V3, P3) is extracted as (exhaust flow velocity, differential pressure) corresponding to the region γ is shown.

  Then, as shown in FIG. 6, a midpoint S1C of a line segment S1 connecting Q1 (V1, P1) and Q2 (V2, P2) is determined, and a straight line T1 passing through the midpoint S1C and orthogonal to the line segment S1 is determined. Similarly, the midpoint S2C of a line segment S2 connecting Q2 (V2, P2) and Q3 (V3, P3) is determined, and a straight line T2 passing through the midpoint S2C and orthogonal to the line segment S2 is determined. Then, an intersection C1 (center of curvature) of the straight line T1 and the straight line T2 is determined. The distance from the intersection C1 to Q2 (V2, P2), or the distance from the intersection C1 to Q1 (V1, P1), or the distance from the intersection C1 to Q3 (V3, P3) is the radius of curvature R1 of the detection characteristic .

  Here, the description returns to the flowchart of FIG. 3. When the process proceeds to step S420, the control device 50 has (exhaust flow velocity, differential pressure) that can be used for evaluation of the following steps S425 and S430 among a plurality of (exhaust flow velocity, differential pressure) stored in the storage device. If there is (Yes), the process proceeds to step S425. If not (No), the process ends (no determination is made as to normal or abnormal for the DPF and the diffusion member, and the process ends). In the case of the above example, the control device 50 determines “Yes” when there is the corresponding (exhaust flow velocity, differential pressure) in all the regions α, β, and γ shown in FIG. If there is no corresponding (exhaust flow velocity, differential pressure) in any of the regions, it is determined as "No" and the process is ended.

  When the process proceeds to step S425, as described above, the control device 50 sets the (exhaust flow velocity, differential pressure) of the region α, the (exhaust flow velocity, differential pressure) of the region β, and the (exhaust flow velocity, differential pressure) of the region γ. The radius of curvature of the detection characteristic is calculated using this, and the process proceeds to step S430.

  In step S430, the control device 50 determines whether or not the curvature radius of the detection characteristic calculated in step S425 is smaller than the "curvature radius of the evaluation characteristic" stored in the storage device, and the curvature of the detection characteristic If the radius is smaller than the curvature radius of the evaluation characteristic (Yes), the process proceeds to step S450. If not (No), the process proceeds to step S550.

  When the process proceeds to step S450, the control device 50 determines that the DPF is abnormal and the diffusion member is abnormal, and ends the process.

  When the process proceeds to step S550, the control device 50 determines that the DPF is normal and the diffusion member is normal, and ends the process. Steps S220 to S550 described above correspond to the abnormality determination step of determining each of the DPF abnormality and the diffusion member abnormality based on the detection target part differential pressure according to the operating state of the internal combustion engine.

  In the above description, the curvature radius of the detection characteristic (corresponding to the exhaust flow velocity and the detection target differential pressure characteristic) is compared with the curvature radius of the evaluation characteristic, and when the curvature radius of the detection characteristic is smaller, the DPF and the diffusion member It was determined that both were abnormal. However, using the curvature instead of the curvature radius, the curvature of the detection characteristic is compared with the curvature of the evaluation characteristic, and when the curvature of the detection characteristic is larger than the curvature of the evaluation characteristic, both DPF and the diffusion member are abnormal. It may be determined that there is. The radius of curvature and the method of obtaining the curvature are not particularly limited.

● [Effect of this application]
The exhaust gas purification apparatus for an internal combustion engine and the exhaust gas purification apparatus for an internal combustion engine according to the above-described method, the exhaust gas for an internal combustion engine having a diffusion member for mixing and diffusing a reducing agent into exhaust gas, a selective reduction catalyst, and a DPF. In the purification device, it is possible to determine an abnormality in each of the diffusion member and the DPF by one differential pressure detection means.

  The exhaust gas purification apparatus for an internal combustion engine and the abnormality determination method for an exhaust gas purification apparatus for an internal combustion engine according to the present invention are not limited to the configuration, structure, shape, processing procedure, etc. described in the present embodiment. Various changes, additions, and deletions are possible without changing the settings.

  The exhaust flow velocity / differential pressure characteristics shown in the present embodiment are not limited to the example shown in FIG.

  Further, the above (≧), the following (≦), the larger (>), the less than (<), etc. may or may not include the equal sign. Further, the numerical values used in the description of the present embodiment are an example, and the present invention is not limited to these numerical values.

DESCRIPTION OF SYMBOLS 10 internal combustion engine 11 intake path 12 exhaust path 21 addition valve 22 reductant tank 23 pump 26 pressure detection means 28 fuel injection valve 31 intake air flow rate detection means 32 NOx detection means 33 accelerator opening degree detection means 34 rotation detection means 36A, 36B, 36C Exhaust temperature detection means 38 Differential pressure detection means 38A upstream side pipe 38B downstream side pipe 41 first oxidation catalyst 42 SCRF
42A DPF (fine particle collection filter)
42B Selective reduction catalyst 43 DPF (fine particle collection filter)
44 selective reduction catalyst 46 second oxidation catalyst 48 diffusion member 49A, 49B detection target unit 50 control device (abnormality determination device)

Claims (8)

A particulate collection filter disposed in an exhaust path of an internal combustion engine to capture particulate matter in the exhaust;
A selective reduction catalyst disposed in the exhaust path,
An addition valve which is disposed upstream of the exhaust gas with respect to the selective reduction catalyst in the exhaust gas path and sprays a reducing agent toward the diffusion member;
The diffusion member disposed upstream or downstream near the addition valve in the exhaust path to diffuse the reducing agent sprayed from the addition valve into exhaust gas;
Pressure of exhaust gas in the exhaust path upstream of the detection target portion including the particulate collection filter and the diffusion member; pressure of exhaust gas in the exhaust path downstream of the detection target portion Differential pressure detection means for detecting a differential pressure to be detected which is a differential pressure;
An abnormality in the particulate matter collection filter and the abnormality in the particulate matter collection filter can be detected based on the detected operation state and the detection target portion differential pressure detected by the differential pressure detection means while being capable of detecting the operation state of the internal combustion engine An abnormality determination device capable of determining each of the diffusion member's abnormalities;
Have
Exhaust purification system for internal combustion engines. An exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein
The abnormality determination device is
In the case where the operating condition satisfies a predetermined operating condition,
Each of an abnormality of the particulate matter collection filter and an abnormality of the diffusion member is determined based on the detection target portion differential pressure with respect to an exhaust flow velocity which is a flow velocity of exhaust in the exhaust passage.
Exhaust purification system for internal combustion engines. An exhaust gas purification apparatus for an internal combustion engine according to claim 2, wherein
The abnormality determination device is
When the operating condition satisfies the predetermined operating condition,
It is determined that the diffusion member is abnormal if the differential pressure to be detected relative to the exhaust flow velocity is a differential pressure greater than the upper limit characteristic for which the upper limit differential pressure relative to the exhaust flow velocity is set,
It is determined that the particulate matter collection filter is abnormal when the differential pressure to be detected with respect to the exhaust gas flow velocity is smaller than the lower limit characteristic at which the lower limit differential pressure with respect to the exhaust gas flow velocity is set.
Exhaust purification system for internal combustion engines. An exhaust gas purification apparatus for an internal combustion engine according to claim 3, wherein
The abnormality determination device is
When the operating condition satisfies the predetermined operating condition,
When the differential pressure to be detected with respect to the exhaust flow velocity is equal to or less than the upper limit characteristic and equal to or more than the lower limit characteristic,
Detecting a differential pressure of each of the detection target portions with respect to the plurality of exhaust gas flow rates;
When the curvature of the exhaust flow velocity / the detection target differential pressure characteristic connecting each detection target portion differential pressure to the each exhaust flow velocity is a curvature larger than the curvature of the evaluation characteristic set in advance, the particulate trapping is performed. Determining that both the collecting filter and the diffusing member are abnormal,
Exhaust purification system for internal combustion engines. A particulate collection filter disposed in an exhaust path of an internal combustion engine to capture particulate matter in the exhaust;
A selective reduction catalyst disposed in the exhaust path,
An addition valve which is disposed upstream of the exhaust gas with respect to the selective reduction catalyst in the exhaust gas path and sprays a reducing agent toward the diffusion member;
The diffusion member disposed upstream or downstream near the addition valve in the exhaust path to diffuse the reducing agent sprayed from the addition valve into exhaust gas;
An exhaust gas control apparatus for an internal combustion engine, comprising: an exhaust gas purification apparatus having an exhaust gas purification unit for detecting an abnormality in the particulate matter collection filter and an abnormality in the diffusion member;
Pressure of exhaust gas in the exhaust path upstream of the detection target portion including the particulate collection filter and the diffusion member; pressure of exhaust gas in the exhaust path downstream of the detection target portion Differential pressure detection means for detecting a differential pressure to be detected which is a differential pressure;
An abnormality determination device,
Using
An operating state detection step of detecting an operating state of the internal combustion engine by the abnormality determination device;
A differential pressure detection step of detecting the target differential pressure in accordance with the detected operating condition by the abnormality determination device;
An abnormality determination step of determining each of an abnormality of the particulate matter collection filter and an abnormality of the diffusion member on the basis of the detection target portion differential pressure according to the operation state in the abnormality determination device;
Have
An abnormality determination method for an exhaust gas purification device for an internal combustion engine. The method for determining abnormality of an exhaust gas purification apparatus for an internal combustion engine according to claim 5, wherein
When the operating condition detected in the operating condition detecting step satisfies a predetermined operating condition, the differential pressure detecting step detects the differential pressure of the detection target together with the exhaust flow velocity which is the flow velocity of the exhaust in the exhaust passage. And
In the abnormality determination step, each of an abnormality of the particulate matter collection filter and an abnormality of the diffusion member is determined based on the detection target portion differential pressure with respect to the exhaust gas flow velocity.
An abnormality determination method for an exhaust gas purification device for an internal combustion engine. 7. The method for determining abnormality of an exhaust gas purification apparatus for an internal combustion engine according to claim 6, wherein
In the abnormality determination step,
It is determined that the diffusion member is abnormal if the differential pressure to be detected relative to the exhaust flow velocity is a differential pressure greater than the upper limit characteristic for which the upper limit differential pressure relative to the exhaust flow velocity is set,
It is determined that the particulate matter collection filter is abnormal when the differential pressure to be detected with respect to the exhaust gas flow velocity is smaller than the lower limit characteristic at which the lower limit differential pressure with respect to the exhaust gas flow velocity is set.
An abnormality determination method for an exhaust gas purification device for an internal combustion engine. 8. The method for determining abnormality of an exhaust gas purification apparatus for an internal combustion engine according to claim 7, wherein
In the abnormality determination step,
When the detection target differential pressure with respect to the exhaust flow velocity is equal to or lower than the upper limit characteristic and equal to or higher than the lower limit characteristic, the detection target differential pressure is detected for each of the plurality of exhaust flow velocities;
When the curvature of the exhaust flow velocity / the detection target differential pressure characteristic connecting each detection target portion differential pressure to the each exhaust flow velocity is a curvature larger than the curvature of the evaluation characteristic set in advance, the particulate trapping is performed. Determining that both the collecting filter and the diffusing member are abnormal,
An abnormality determination method for an exhaust gas purification device for an internal combustion engine.

Images