JP5574120B2 - Diagnostic device for NOx purification system - Google Patents

Description

  The present invention relates to a diagnostic apparatus for a NOx purification system, and more particularly to a diagnostic apparatus for confirming whether a repaired NOx purification system functions normally based on a failure diagnosis.

In recent years, a NOx purification system in which a NOx catalyst is arranged in an exhaust passage of an engine has been put into practical use. For example, in a diesel engine, combustion is performed under a lean air-fuel ratio, so the amount of oxygen (O ₂ ) in the exhaust gas is large, and the three-way catalyst that is put to practical use in gasoline engines does not function, and various diesel engines NOx catalysts have been developed. As one of these, a NOx purification system using an ammonia selective reduction type NOx catalyst (hereinafter referred to as an SCR catalyst) configured to add ammonia as a reducing agent that has been put into practical use in a land-type diesel engine has recently been used in vehicles. It is being developed for use. In this type of SCR catalyst, the reaction proceeds so that NOx is reduced to nitrogen (N ₂ ) and H ₂ O by ammonia (NH ₃ ) added onto the catalyst.

By the way, this type of NOx purification system may cause failure due to various factors during operation, and continuation of operation in the failure state leads to NOx emission into the atmosphere. Is required by law. As an example of the failure diagnosis apparatus, one described in Patent Document 1 can be cited.
In this failure diagnosis device, the amount of ammonia added onto the SCR catalyst is changed, and the presence or absence of a failure is determined based on the detection value of the NOx sensor disposed on the downstream side of the SCR catalyst. Such a failure diagnosis device always operates while the NOx purification system is operating by engine operation and monitors the failure. When a failure is determined, the SCR failure lamp provided in the driver's seat is turned on to notify the driver of the failure. By doing so, repairs at dealers that handle vehicle sales and repairs are encouraged.

  In addition, as a countermeasure against incomplete repairs at dealers and the like, work is performed to confirm that the function has been restored by actually operating the NOx purification system after the repair is completed. As is well known, the SCR catalyst exhibits good NOx purification performance only in the active temperature range, and if the catalyst temperature falls below the lower limit value (the lower active temperature limit) of the active temperature range, it is sufficient even if ammonia is added. Does not demonstrate the cleansing performance. For this reason, the confirmation work after the repair is performed after actually driving the vehicle and raising the temperature of the SCR catalyst to the activation temperature range.

JP 2010-248963 A

  However, the activity lower limit temperature of the SCR catalyst is a high temperature of about 180 ° C., and in order to raise the temperature of the SCR catalyst to at least the activity lower limit temperature, for example, it is necessary to continue traveling at 100 km / h for about 30 minutes. There was a problem that it took time and effort. In addition, even within the active temperature range, the NOx purification performance of the SCR catalyst depends on the catalyst temperature and varies with the catalyst temperature. Since the catalyst temperature fluctuates in accordance with the exhaust temperature of the engine and thus the running state of the vehicle, the NOx purification performance also fluctuates during the checking operation due to the influence, and the determination accuracy as to whether the function is restored decreases. There is also a problem.

In addition, although it is possible to use the failure diagnosis device of Patent Document 1 for the confirmation work of functional recovery of the NOx purification system, it is impossible to solve the above-mentioned problem due to vehicle running for catalyst temperature rise. Is clear.
The present invention has been made to solve such problems, and the object of the present invention is to perform functional confirmation of the NOx purification system repaired based on the failure diagnosis with high accuracy in a short time. An object of the present invention is to provide a diagnostic apparatus for a NOx purification system that can perform the above-mentioned.

  In order to achieve the above object, an invention according to claim 1 is an ammonia selective reduction type NOx catalyst which is disposed in an exhaust passage of an engine and selectively purifies NOx in exhaust gas by adding a reducing agent, and an ammonia selective reduction type. In a NOx purification system comprising at least a reducing agent supply means for supplying a reducing agent to the NOx catalyst, a filter that is disposed on the upstream side of the ammonia selective reduction type NOx catalyst in the exhaust passage and collects particulates in the exhaust gas; When the driver operates the regeneration start switch in response to a notification from the over-deposition notification unit, the temperature of the filter is raised and caught while the vehicle is stopped. Manual regeneration means for performing manual regeneration for forcibly removing the collected particulates by incineration, and the ammonia selective reduction type N in the exhaust passage x NOx detection means disposed downstream of the catalyst, and function confirmation instruction means for instructing whether or not the function of the NOx purification system has been restored after the repair of the NOx purification system based on the failure determination of the failure diagnosis means Is operated, even when there is no notification by the over-deposition notification means, the manual regeneration means performs manual regeneration, and the ammonia selective reduction type NOx catalyst on the downstream side is at least activated lower limit temperature along with the temperature rise of the filter by manual regeneration. And a function confirming means for judging the recovery of the function of the NOx purification system on the basis of the detected value of the NOx detecting means when the temperature is raised to.

According to the second aspect of the present invention, when the temperature of the ammonia selective reduction type NOx catalyst reaches the temperature rise end temperature set near the lower limit of activation temperature, the function confirmation unit causes the manual regeneration unit to end the manual regeneration. is there.
According to a third aspect of the present invention, in the first or second aspect, the function confirmation instructing means is a regeneration start switch provided in a driver's seat of the vehicle, and the function confirmation means is overdeposited when the regeneration start switch is operated. Only when there is no notification by the notification means, the function recovery determination is executed following the manual regeneration.

According to a fourth aspect of the present invention, in the first or second aspect, the function confirmation instructing means is a diagnostic tool connectable to the function confirming means, and the function confirmation means inputs the start of the function confirmation mode by the diagnostic tool In the function confirmation mode, the function recovery determination is executed following the manual regeneration.
According to a fifth aspect of the present invention, in the fourth aspect, in addition to the function confirmation mode, the function confirmation means sequentially changes the operation state of each component of the NOx purification system and prepares for manual operation for changing the operation state. It is possible to execute a failure investigation mode that sequentially instructs the diagnostic tool to display the preparation contents and determines whether the configuration whose operating state has been changed is the cause of the failure of the NOx purification system based on the detected value of the NOx detection means. Yes, the failure investigation mode is started at the timing after the NOx purification system function has been restored in the function confirmation mode, or at the timing before the repair of the NOx purification system. It is determined sequentially, and a repair instruction for the identified cause of failure is displayed on the diagnostic tool.

As described above, according to the diagnosis apparatus for the NOx purification system of the first aspect of the present invention, when the function confirmation instruction means for instructing the function recovery is operated after the repair of the NOx purification system based on the failure diagnosis, Even when there is no notification by the notification means and manual regeneration is not required to prevent over-deposition of the filter, manual regeneration is performed. The function recovery of the NOx purification system is determined based on the detected value of the NOx detecting means when the temperature is raised to at least the lower limit temperature of activity.
Since the temperature of the ammonia selective reduction type NOx catalyst is raised by using manual regeneration in this way, it is possible to prevent labor and time consumption due to traveling of the vehicle for raising the temperature, and the function of the NOx purification system easily and in a short time. Confirmation can be performed. In addition, when the catalyst temperature rises due to manual regeneration as compared with the catalyst temperature rise due to vehicle running, the catalyst temperature fluctuates less and it can be determined with high accuracy whether or not the function has been recovered.

According to the diagnostic apparatus for the NOx purification system of the second aspect of the invention, the manual regeneration is terminated when the temperature of the ammonia selective reduction type NOx catalyst reaches the temperature rise end temperature near the activation lower limit temperature. Since the temperature decrease of the ammonia selective reduction type NOx catalyst after the end of the manual regeneration becomes slow due to the heat mass, the function confirmation of the NOx purification system is completed before the catalyst temperature falls below the lower limit activation temperature. Further, it is possible to save fuel consumption by limiting the execution time of manual regeneration to the minimum necessary, and to prevent adverse effects of fuel consumption deterioration.
According to the diagnostic apparatus for the NOx purification system of the third aspect of the present invention, when the regeneration start switch as the function confirmation instruction means is operated, when there is no notification by the overdeposition notification means, the filter is not overdeposited and NOx It was assumed that the function confirmation after repair of the purification system was instructed, and the function recovery judgment was executed following the manual regeneration. As described above, since the existing regeneration start switch is used as the function confirmation instruction means, it is possible to instruct the function confirmation after the repair of the NOx purification system without adding equipment, and the manufacturing cost can be reduced.

According to the diagnostic apparatus for the NOx purification system of the fourth aspect of the present invention, when the start of the function confirmation mode is input by the diagnostic tool, the function recovery determination is executed following the manual regeneration. In this way, it is possible to instruct function confirmation after repair of the NOx purification device by simply connecting a diagnostic tool to the function confirmation means without adding equipment on the vehicle side, and the manufacturing cost can be reduced.
According to the diagnosis device for the NOx purification system of the fifth aspect of the present invention, the failure investigation mode is performed at the timing after determining that the function of the NOx purification system is not recovered in the function confirmation mode, or at the timing before repairing the NOx purification system. In this failure investigation mode, the operation state of each component of the NOx purification system is changed and sequentially inspected, and if necessary, a preparation instruction for the mechanic is displayed on the diagnostic tool, thereby configuring the cause of the failure specified. The repair instruction of was displayed on the diagnostic tool.

Therefore, when it is determined that the function of the NOx purification system has not been restored by the initial repair, the configuration of the NOx purification system that causes the failure is identified by the failure investigation mode, and the repair is performed again based on the display of the diagnostic tool. The function confirmation mode is executed again after the repair. Alternatively, the failure investigation mode is executed before the initial repair, the configuration of the NOx purification system causing the failure is specified, and the function check mode is executed after the initial repair is performed based on the repair instruction displayed on the diagnostic tool. The
In any case, the failure investigation mode automatically checks each component of the NOx purification system sequentially, so even unskilled mechanics can easily identify the cause of failure, and when the mechanic needs to be prepared to change the operating state. Since the preparation instruction is displayed on the diagnostic tool, the mechanic's useless labor due to inappropriate preparation can be reduced.

1 is an overall configuration diagram showing a diesel engine to which a diagnostic device for a NOx purification system of the present invention is applied. It is a flowchart which shows the SCR temperature rising and function confirmation routine which ECU of 1st Embodiment performs. It is a time chart which shows the procedure of the function confirmation after repair of the NOx purification system by the process of ECU of 1st Embodiment. It is a flowchart which shows the SCR temperature rising and function confirmation routine which ECU of 2nd Embodiment performs. It is a flowchart which shows the failure investigation routine which ECU of 2nd Embodiment performs. It is a time chart which shows the procedure of the function confirmation after a repair of a NOx purification system by the process of ECU of 2nd Embodiment, and a failure investigation.

[First Embodiment]
Hereinafter, a first embodiment of a diagnostic apparatus for a NOx purification system embodying the present invention will be described.
FIG. 1 is an overall configuration diagram showing a diesel engine to which a diagnostic device for a NOx purification system of the present invention is applied. The engine 1 is configured as an in-line 6-cylinder engine. Each cylinder of the engine 1 is provided with a fuel injection valve 2, and each fuel injection valve 2 is supplied with pressurized fuel from a common common rail 3 and is opened at a timing according to the operating state of the engine. The fuel is injected into the inside.
An intake manifold 4 is mounted on the intake side of the engine 1, and an intake passage 5 connected to the intake manifold 4 is provided with an air cleaner 6, a compressor 7 a of a turbocharger 7, and an intercooler 8 from the upstream side. An exhaust manifold 9 is mounted on the exhaust side of the engine 1, and an exhaust passage 10 is connected to the exhaust manifold 9 via a turbine 7b of a turbocharger 7 coaxially connected to the compressor 7a.

The intake air introduced into the intake passage 5 via the air cleaner 6 during operation of the engine 1 is pressurized by the compressor 7a of the turbocharger 7 and then distributed to each cylinder via the intercooler 8 and the intake manifold 4, and the intake air of each cylinder It is introduced into the cylinder in the process. In the cylinder, fuel is injected from the fuel injection valve 2 at a predetermined timing and ignited and combusted in the vicinity of the compression top dead center. The exhaust gas after combustion rotates the turbine 7b through the exhaust manifold 9, and then passes through the exhaust passage 10. It is discharged outside.
The intake manifold 4 and the exhaust manifold 9 are connected by an EGR passage 12 for exhaust gas recirculation, and an EGR valve 13 and an EGR cooler 14 are interposed in the EGR passage 12. The exhaust gas in the exhaust manifold 9 is recirculated to the intake manifold 4 as EGR gas according to the opening of the EGR valve 13, and the recirculated EGR gas suppresses the combustion temperature in the cylinder of each cylinder to reduce the amount of NOx generated. Has the effect of

The exhaust passage 10 is provided with an exhaust purification device. A upstream oxidation catalyst 17 and a DPF (diesel particulate filter) 18 are accommodated in the upstream casing 16 of the exhaust purification device from the upstream side, and an SCR catalyst (ammonia selection) from the upstream side in the downstream casing 19 of the exhaust purification device. A reduction type NOx catalyst) 20 and a post-stage oxidation catalyst 21 are accommodated.
The upstream casing 16 and the downstream casing 19 are connected by a mixing passage 22, and an injection nozzle 23 (reducing agent supply means) for injecting urea water is disposed in the mixing passage 22. The tip of the injection nozzle 23 is positioned at the center in the mixing passage 22, and the base end of the injection nozzle 23 is connected to an electromagnetic valve 23 a installed on the outer periphery of the mixing passage 22. A predetermined amount of urea water is supplied to the electromagnetic valve 23a from a urea tank (not shown), and urea water is radially injected from the tip of the injection nozzle 23 in response to opening and closing of the electromagnetic valve 23a.

  On the other hand, an input / output device (not shown), a storage device (ROM, RAM, etc.) used for storing control programs and control maps, a central processing unit (CPU), a timer counter, etc. Control unit) 31 is installed. On the input side of the ECU 31, there are a temperature sensor 32 for detecting the exhaust temperature Tex1 introduced into the SCR catalyst 20, a temperature sensor 37 for detecting the exhaust temperature Tex2 after passing through the rear-stage oxidation catalyst 21 via the SCR catalyst 20, and the driver's seat. An SCR failure lamp 33 for indicating a failure of the installed NOx purification system, a DPF over-deposition lamp 34 (over-deposition notification means) for notifying over-deposition of the DPF 18 also installed in the driver's seat, and a DPF 18 also installed in the driver's seat A regeneration start switch 35 (function confirmation instruction means) for starting manual regeneration, a NOx sensor 36 (NOx selection means) for detecting the amount of NOx contained in the exhaust gas after flowing through the post-stage oxidation catalyst 21 via the SCR catalyst 20, etc. Sensors are connected. Further, devices such as the fuel injection valve 2, the EGR valve 13, and the electromagnetic valve 23 a of the injection nozzle 23 are connected to the output side of the ECU 31.

For example, the ECU 31 sets a fuel injection amount according to a map (not shown) from the engine rotation speed Ne and the accelerator operation amount θacc, sets a fuel injection timing according to a map (not shown) from the engine rotation speed Ne and the fuel injection amount, and these fuel injection amounts. The engine 1 is operated by drivingly controlling the fuel injection valve 2 based on the fuel injection timing.
Further, the ECU 31 discriminates the EGR execution region and the non-execution region from the fuel injection amount Q and the engine speed Ne according to a predetermined map. In the EGR execution region, the EGR valve 13 is opened based on the target EGR amount set from the map. Control the degree. Thus, in the EGR execution region, exhaust gas is recirculated to the intake side as EGR gas, thereby suppressing the combustion temperature in the cylinder of each cylinder and achieving reduction in NOx generation.

In addition, the ECU 31 drives and controls the electromagnetic valve 23 a to inject urea water from the injection nozzle 23 in order to supply ammonia onto the SCR catalyst 20 to exert a NOx purification action. The target injection amount of the urea water is determined based on the temperature Tcat of the SCR catalyst 20, and when the catalyst temperature Tcat is lower than the activation lower limit temperature Tlo, the target injection amount is set to 0 (injection stop), while being higher than the activation lower limit temperature Tlo. Sometimes, the higher the higher temperature side, the higher the target injection amount is set on the increasing side, thereby realizing proper ammonia addition.
For example, the catalyst temperature Tcat is determined based on the exhaust temperature Tex1 which is the upstream temperature of the SCR catalyst 20 detected by the temperature sensor 32 and the exhaust temperature Tex2 which is the downstream temperature of the SCR catalyst 20 detected by the temperature sensor 37. It is sequentially calculated by the ECU 31 during the operation of 1. However, the method for calculating the catalyst temperature Tcat is not limited to this. For example, the catalyst temperature Tcat may be estimated from the exhaust gas temperature Tex1.

During operation of the engine 1, exhaust gas discharged from the engine 1 is introduced into the upstream casing 11 through the exhaust manifold 9 and the exhaust passage 10, and is contained when flowing through the DPF 15 through the pre-stage oxidation catalyst 14. PM (particulate matter) is collected. Thereafter, urea water is injected from the injection nozzle 23 in the mixing passage 22 and the urea water is hydrolyzed by exhaust heat and water vapor in the exhaust gas to generate ammonia.
The generated ammonia reduces NOx in the exhaust gas to harmless N ₂ on the SCR catalyst 20 to purify NOx, while the excess ammonia at this time is oxidized to NO by the post-stage oxidation catalyst 21 and processed. Is done.

The PM collected in the DPF 18 is incinerated and removed due to various factors, whereby the DPF 18 is regenerated. For example, in an operation state in which the exhaust temperature Tex of the engine 1 is relatively high, NO ₂ is generated from NO in the exhaust gas by the oxidation action on the pre-stage oxidation catalyst, and the NO ₂ undergoes an oxidation reaction on the DPF 18 so that PM continuously Incinerated (continuous regeneration).
In addition, when the action of continuous regeneration cannot be obtained, the amount of PM trapped on the DPF 18 exceeds the limit, resulting in overdeposition. Therefore, for example, the ECU 31 calculates the pressure loss at the DPF 18 based on the detection values of the pressure sensors (not shown) provided on the upstream side and the downstream side of the DPF 18, and the pressure loss exceeds the determination value set near the PM collection limit. Sometimes, it is determined that PM is excessively accumulated, and PM is forcibly removed by incineration (forced regeneration). Forced regeneration is realized by increasing the temperature of the DPF 18 by post-injection after the main injection, etc., but it is possible to perform automatic regeneration performed while the vehicle is traveling and manual regeneration performed while the vehicle is stopped depending on the PM accumulation state on the DPF 18. It can be divided roughly.

Normally, automatic regeneration is performed while the vehicle is running and the DPF 18 is heated. On the other hand, if automatic regeneration is performed due to continuous low-speed traveling or the like, the temperature of the DPF 18 is insufficient and PM cannot be incinerated. This notification prompts execution of manual regeneration. This notification is performed by the DPF over-deposition lamp 34, and the driver recognizes the necessity of manual regeneration by the DPF over-deposition lamp 34 lit by the ECU 31, and after stopping the vehicle at the nearest safe place, the regeneration start switch 35 is pressed. In response to the switch operation, the ECU 31 starts manual regeneration while operating the engine 1 under the optimum conditions for increasing the temperature of the DPF 18.
Both automatic regeneration and manual regeneration are subdivided into a plurality of stages according to the temperature raising process of the DPF 18, and are composed of, for example, preliminary temperature raising control, ascending control and descending control. The preliminary temperature increase control is a control that is executed while suppressing the post injection amount mainly for the purpose of increasing the temperature of the pre-stage oxidation catalyst 17 (for example, 290 to 300 ° C.). The ascending control and the descending control are executed alternately after the completion of the preliminary temperature increase control, and both increase the post injection amount compared to the preliminary temperature increase control and supply it to the pre-stage oxidation catalyst 17. The purpose is to maintain the downstream DPF 18 at a temperature equal to or higher than the combustion temperature of PM (for example, 600 ° C.) by combustion of HC and CO.

Note that automatic regeneration and manual regeneration are not limited to post-injection, and various methods can be used. For example, fuel is injected from a fuel injection valve provided in the exhaust passage 10 and HC and CO are supplied to the pre-stage oxidation catalyst 17 for combustion, or an exhaust throttle valve (not shown) is controlled to be closed, or these methods are used. May be combined.
As described above, the emission of various harmful components such as NOx and PM contained in the exhaust gas of the engine 1 into the atmosphere is suppressed. As for NOx, the respective NOx purification systems described below function in cooperation with each other to achieve the desired NOx purification performance.

As each configuration of the NOx purification system, first, an SCR catalyst 20 that directly exerts an NOx purification action, and a urea injection system (injection nozzle 23 or the like) for adding ammonia to the SCR catalyst 20 can be exemplified. An EGR system (EGR passage 12, EGR valve 13, and EGR cooler 14) for suppressing the generation of NOx in the cylinder of the engine 1 is also one of the configurations of the NOx purification system. Further, a map for deriving the fuel injection amount and fuel injection timing of the engine 1 is optimally set from calibration based on a prior bench test, and fuel injection control is executed based on these maps to perform in-cylinder Since NOx and PM generation is suppressed as much as possible, the fuel injection control of the engine 1 can be regarded as one of the configurations of the NOx purification system in that sense.
In other words, if any configuration of these NOx purification systems breaks down and the function is hindered, the amount of NOx discharged into the atmosphere will increase.

Assuming such a failure of the NOx purification system, the ECU 31 has a function of a failure diagnosis device (failure diagnosis means). As the failure diagnosis device, for example, the technique described in Patent Document 1 can be used, and the urea injection amount from the injection nozzle 23 is intentionally changed from the target injection amount every predetermined time during the operation of the engine 1. The presence or absence of a failure is determined based on the detected value of the NOx sensor 36. When the failure determination is made, the SCR failure lamp 33 is blinked at a predetermined cycle to notify the driver of the failure of the NOx purification system.
The driver brings the vehicle to a dealer or the like for repair, and the dealer identifies the cause of the failure and performs repairs such as parts replacement. Note that the failure diagnosis device is not limited to the above example, and failure diagnosis may be performed using another method.

The increase factor of the NOx emission amount (the detected value of the NOx sensor 36 on the downstream side of the SCR catalyst 20) varies depending on the failure occurrence location of the NOx purification system, and the repair contents are also varied accordingly. For example, when the SCR catalyst 20 is damaged or deteriorated, the NOx purification performance of the SCR catalyst 20 decreases from the expected value, so that the amount of NOx in the exhaust gas on the downstream side of the catalyst, and thus the amount of NOx discharged into the atmosphere, increases. . The repair in this case is dealt with by replacing the SCR catalyst 20 or the like.
Also, if the urea injection system fails due to clogging of the injection nozzle 23 or poor opening / closing of the solenoid valve 23a, the amount of urea water injected becomes inappropriate, and the SCR catalyst 20 itself has an amount necessary for NOx reduction even if there is no problem. Since ammonia is not supplied, the NOx purification performance decreases. In this case as well, the amount of NOx in the exhaust gas on the downstream side of the catalyst increases, and this is dealt with by replacing the faulty part of the urea injection system or cleaning the injection nozzle 23.

Similarly, if the EGR system breaks down due to clogging of the EGR passage 12 or malfunction of the EGR valve 13, the amount of NOx generated in the cylinder of the engine 1 increases, and the SCR catalyst 20 exhibits the desired NOx purification performance. However, NOx emissions into the atmosphere will increase. In this case, the repair is dealt with by replacing a faulty part of the EGR system or cleaning the EGR passage 12.
In addition, when a problem occurs in the fuel injection control of the engine 1 due to clogging or opening / closing failure of the fuel injection valve 2 of any cylinder, the NOx generation amount in the cylinder of the specific cylinder is similar to the case of the EGR system. As a result, the NOx emission amount into the atmosphere increases even when the SCR catalyst 20 is normal. The repair in this case is dealt with by replacing or cleaning the failed fuel injection valve 2.

The repair according to the cause of the failure as described above is performed at the dealer, and after the repair is completed, the NOx purification system is actually operated to confirm that the function is restored, and the NOx purification system is confirmed by the confirmation work. After the functional recovery of the vehicle is confirmed, it is determined that the repair is complete and the vehicle can be operated.
Here, as described in [Problems to be Solved by the Invention], according to the conventional confirmation work, the vehicle is driven to operate the NOx purification system and the SCR catalyst 20 is raised to at least the activation lower limit temperature Tlo. Since it is necessary to warm, there is a problem that much labor and time are required, and accurate determination is difficult due to fluctuations in the catalyst temperature Tcat according to the running state of the vehicle.
Therefore, in the present embodiment, the function of the NOx purification system is confirmed without running the vehicle by using the manual regeneration function of the DPF 18 provided in the ECU 31 to raise the temperature of the SCR catalyst 20 located on the exhaust downstream side. Hereinafter, the procedure of the function confirmation process will be described in detail.

The ECU 31 executes the SCR temperature increase / function confirmation routine shown in FIG. 2 at a predetermined control interval during the operation of the engine 1. First, the ECU 31 determines whether or not the regeneration start switch 35 has been operated in step S2, and once the determination is No (No), the routine is once terminated. Here, the reproduction start switch 35 is operated in the following two situations. One is a case where the driver recognizes the excessive accumulation of the DPF 18 based on the lighting of the DPF excessive accumulation lamp 34 and the regeneration start switch 35 is operated to manually regenerate the DPF 18. The other case is when the repair of the NOx purification system is completed by the mechanic based on the lighting of the SCR failure lamp 33 and the regeneration start switch 35 is operated to confirm the function.
In the latter case, since the DPF 18 has not yet been over-deposited, the ECU 31 does not start manual regeneration even if the regeneration start switch 35 is normally operated. However, in the present embodiment, as described below, Manual regeneration is started even when the switch is operated in various situations.

When the regeneration start switch 35 is pressed, the ECU 31 makes a “Yes” determination in step S2 and proceeds to step S4 to determine whether or not the DPF over-deposition lamp 34 is lit. The process of step S4 is for determining which of the above factors is the operation of the reproduction start switch 35. If the determination in step S4 is Yes, that is, if the switch is operated for the purpose of manual regeneration of the DPF 18, the process proceeds to step S6 to execute manual regeneration of the DPF 18, and after completion, the DPF over-deposition lamp 34 is turned off in step S8. Exit the routine.
Although the details of manual regeneration are not different from normal, they will not be described in detail. However, after performing preliminary temperature rise control to raise the temperature of the pre-stage oxidation catalyst as described above, PM control is performed alternately by raising and lowering control. Maintain DPF 18 above temperature. As a result, the PM is forcibly removed by incineration, and the DPF 18 is regenerated.

On the other hand, when the determination in step S4 is No, that is, when the regeneration start switch 35 is operated for the purpose of confirming the function after the repair of the NOx purification system, the mechanic recognizes that the function confirmation has been started in step S10. The SCR failure lamp 33 is switched from the blinking state to the lighting state. In step S12, manual regeneration is started, and in subsequent step S14, it is determined whether or not the temperature Tcat of the SCR catalyst 20 has reached the temperature rise end temperature T0. Due to the oxidation reaction on the pre-stage oxidation catalyst 17 by the post-injection of manual regeneration and the PM combustion on the DPF 18, not only the DPF 18 but also the SCR catalyst 20 located on the downstream side is heated while the manual regeneration is continued. Tcat gradually increases.
Here, the temperature rise end temperature T0 is set to a value slightly higher than the activation lower limit temperature Tlo of the SCR catalyst 20. The temperature drop of the SCR catalyst 20 when the manual regeneration is finished becomes slow due to the heat mass of the exhaust purification device. In view of this point, the specific temperature rise end temperature T0 is set so that the catalyst temperature Tcat does not fall below the activation lower limit temperature Tlo until a determination time TA (for example, about 5 to 10 minutes) for confirming the function of the NOx purification system elapses. It is set to a valid value.

Since the manual regeneration proceeds from the preliminary temperature rise control to the rise control and the drop control as described above based on the temperature rise state (for example, DPF temperature) on the DPF 18 side, the progress of manual regeneration and the temperature Tcat of the SCR catalyst 20 There is no clear correlation between the two. For this reason, the timing at which the catalyst temperature Tcat reaches the temperature rise end temperature T0 differs depending on whether it is during the preliminary temperature rise control or after the transition to the rise control and the drop control, but in any case, the catalyst temperature Tcat. Manual regeneration is continued until the temperature reaches the temperature rise end temperature T0.
In this embodiment, ECU31 when performing the process of the above step S6,12-16 functions as a manual reproduction | regeneration means.
The ECU 31 continues the manual regeneration while the determination in step S14 is No. When the determination is Yes, the ECU 31 stops the manual regeneration in step S16, and performs the function check of the NOx purification system in subsequent steps S18 to S22. Specifically, whether or not the determination time TA has elapsed in step S20 after the entire NOx purification system, such as the operating state of the engine 1 and the operating state of the EGR system and the urea injection system, is set to a predetermined operating state in step S18. In step S22, it is determined whether or not the detected value of the NOx sensor 36 has reached a normal level.

If the detection value of the NOx sensor 36 reaches a normal level before the determination time TA elapses, an OK determination is made, the SCR failure lamp 33 is turned off in step S24, and the completion of the repair is notified. In addition, when the determination time TA has passed without the detection value of the NOx sensor 36 becoming a normal level, an NG determination is made, and in step S26, the SCR failure lamp 33 is blinked again to notify that the repair is not completed. The routine ends later.
Therefore, when the repair of the NOx purification system is not completed, the mechanic recognizes the situation based on the reflashing of the SCR failure lamp 33, repairs another part, and operates the regeneration start switch 35 again. In response to this, the ECU 31 executes the processing after step S2 in the same manner as described above, and the function confirmation of the purification system is performed again.
In this embodiment, ECU31 when performing the process of the above step S2,4,18-26 functions as a function confirmation means.

The function confirmation procedure after repair of the NOx purification system executed by the ECU 31 will be described with reference to the time chart of FIG.
During repair of the NOx purification system by the mechanic, the SCR failure lamp 33 continues to flash, and when the regeneration start switch 35 is operated upon completion of the repair, the SCR failure lamp 33 is switched to the lighting state and manual regeneration of the DPF 18 is started. The The engine speed Ne at this time is adjusted to an optimal value for the purpose of raising the temperature of the DPF 18. As the manual regeneration is continued, the temperature of the SCR catalyst 20 on the downstream side of the DPF 18 is gradually raised. When the catalyst temperature Tcat reaches the temperature rise end temperature T0, the manual regeneration is stopped, and the function of the NOx purification system is checked. The catalyst temperature Tcat slowly decreases due to the heat mass effect of the exhaust gas purification device, and the SCR catalyst 20 is held at the activation lower limit temperature Tlo or higher until the determination time TA elapses, and the function can be confirmed based on the detected value of the NOx sensor 36. Become.

Then, as shown by the solid line in the figure, if an OK determination is made based on the detected value of the NOx sensor 36 before the determination time TA elapses, the SCR failure lamp 33 is turned off and the repair is completed. Further, as indicated by a broken line in the figure, when the determination time TA elapses without the detected value of the NOx sensor 36 being at a normal level and the NG determination is made, the SCR failure lamp 33 blinks again. When the regeneration start switch 35 is operated after repair by a mechanic, the manual regeneration is started and the catalyst temperature Tcat once lowered once again rises to reach the temperature rise end temperature T0, and the function of the NOx purification system is confirmed. . Such repair, manual regeneration, and function confirmation are repeated, and finally, an OK determination is made by function confirmation by appropriate repair, and the repair is completed.
As described above, according to the diagnosis device for the NOx purification system of the present embodiment, when the regeneration start switch 35 is operated after the repair of the NOx purification system based on the failure diagnosis, the DPF over-deposition lamp 34 is turned off and the DPF 18 is overloaded. Even when manual regeneration is not required to prevent accumulation, manual regeneration is performed, and when the SCR catalyst 20 on the downstream side is heated to the temperature rise end temperature T0 as the DPF 18 is heated by manual regeneration. The function recovery of the NOx purification system is determined based on the detection value of the NOx sensor 36.

Since the temperature of the SCR catalyst 20 is raised by using manual regeneration of the DPF 18 in this way, it is possible to prevent labor and time consumption due to vehicle travel for raising the temperature, and the NOx purification system can be simply and quickly. Function check can be performed. In addition, since the catalyst temperature Tcat is less fluctuated in the catalyst temperature increase due to manual regeneration than in the catalyst temperature increase due to vehicle travel, it is possible to determine with high accuracy whether or not the function has been recovered.
In addition, since the function check after the repair of the NOx purification system is instructed by using the existing DPF regeneration start switch 35 without adding equipment, it is possible to prevent an adverse effect of cost increase.
On the other hand, since the manual regeneration is terminated when the temperature Tcat of the SCR catalyst 20 reaches the temperature rise end temperature T0 slightly higher than the activation lower limit temperature Tlo, the execution time of the manual regeneration can be kept to the minimum necessary. Therefore, it is possible to save fuel consumption and prevent adverse effects of fuel consumption deterioration. In addition, since the function confirmation of the NOx purification system is started after the end of the manual regeneration as described above, the function confirmation is performed under the catalyst temperature Tcat that slowly decreases as a result. For example, the catalyst temperature Tcat increases in the manual regeneration preliminary temperature increase control, and the catalyst temperature Tcat repeatedly increases and decreases in the increase control and the decrease control. However, the catalyst temperature Tcat is more stable after the manual regeneration ends than in these situations. Therefore, the determination accuracy of function confirmation can be further improved.

By the way, when repair of the cause of failure is inappropriate and NG judgment is made in the above steps S20 and 22 as a result of function confirmation, the mechanic investigates the cause of failure again at his / her own judgment, and then replaces the part of the failure part. Carry out repairs. For example, when it is not possible to visually determine the presence or absence of a failure, the operating state of each component of the NOx purification system described above is changed and whether or not the component is a failure factor is determined based on the change in the detected value of the NOx sensor 36. to decide.
The change of the operating state of the NOx purification system at this time is performed, for example, in the direction of reducing the NOx emission amount. For example, when the SCR catalyst 20 is damaged or deteriorated, the SCR catalyst 20 in the downstream casing 19 is replaced (resulting in repair). For a malfunction of the urea injection system (clogging of the injection nozzle 23, etc.), the urea injection amount is corrected to increase to, for example, 1.5 times the normal value.
For a failure of the EGR system (such as clogging of the EGR passage 12), the opening degree of the EGR valve 13 is controlled to 100%, or the EGR valve 13 is fully opened. For a failure in the fuel injection control of the engine 1 (clogging of the fuel injection valve 2 or the like), the fuel injection amount is corrected to increase to, for example, 1.5 times the normal value. When the NOx purification system is operated in these states and the NOx amount detected by the NOx sensor 36 is reduced to the normal level, it is determined that the configuration in which the operating state is changed is the cause of the failure, and conversely, the NOx amount is reduced to the normal level. When it does not decrease, it is determined that the configuration is not a cause of failure (other configurations are causes of failure).

Further, the inspection method for investigating the cause of the failure is not limited to this, and for example, the respective components of the NOx purification system may be sequentially stopped. That is, the SCR catalyst 20 in the downstream casing 19 is extracted with respect to the damage or deterioration of the SCR catalyst 20. The urea injection amount is set to 0 for a failure of the urea injection system. For failure of the EGR system, the opening degree of the EGR valve 13 is controlled to 0%, or the EGR valve 13 is manually closed. For the failure of the fuel injection control of the engine 1, the fuel injection amount for each cylinder is set to zero.
In these states, the NOx purification system is operated, and the NOx amount detected by the NOx sensor 36 is determined. If the stopped configuration is not broken, the amount of NOx detected by the NOx sensor 36 increases by a predetermined value corresponding to the contribution of NOx purification to the configuration. On the other hand, if the configuration that has been deactivated has already failed, the increase in the amount of NOx after the deactivation is smaller than the predetermined value (the increase is 0 for a complete failure). Whether it is the cause or not can be determined.

After roughly identifying in which configuration the cause of the failure is in the NOx purification system by the above-described method, a specific failure location in the configuration is found and repaired.
However, in the case of a mechanic who is not proficient in investigating this type of failure cause, even if a configuration that should be considered as the cause of the failure is leaked or an unnecessary configuration is inspected, the cause of the failure cannot or cannot be determined. May take time and effort. Therefore, a series of processing programs for investigating the cause of such a failure is stored in the ECU 31, and if the initial repair is inappropriate, each component of the NOx purification system is automatically and sequentially inspected according to the program. It is possible to identify the cause of failure. Hereinafter, in addition to the function confirmation function after repair, an example in which the ECU 31 executes a failure cause identification process when the initial repair is inappropriate will be described as a second embodiment.

  Here, as is apparent from the above description of the inspection method, the inspection is not only performed by control of the ECU 31 such as correction of increase in the urea injection amount, but also by a mechanic such as replacement of the SCR catalyst 20. Some require manual preparation. Since the preparation work by such a mechanic needs to be performed with the vehicle stopped, the conventional confirmation work of raising the temperature of the SCR catalyst 20 by running of the vehicle cannot be realized at all, and the catalyst is manually regenerated when the vehicle is stopped. This is only possible with the present invention in which the temperature is raised.

[Second Embodiment]
Although the second embodiment will be described below, the overall configuration of the present embodiment is the same as that of the first embodiment shown in FIG. 1, and the main difference is in the processing of the ECU 31. Therefore, description of common parts is omitted, and differences are mainly described.
As shown by a broken line in FIG. 1, a MUT (multi-use tester, diagnostic tool and function confirmation instruction means) 41 can be connected to the ECU 31. As is well known, the MUT 41 is based on a self-diagnosis function of the ECU 31. It is used when reading out the result of failure diagnosis. In the present embodiment, the MUT 41 is used to determine the recovery of the function of the NOx purification system after repair and investigate the cause of the failure, and the ECU 31 operates in response to an input operation to the input unit of the MUT 41 and will be described later. While the function confirmation mode and the failure investigation mode are executed, instructions and instructions for the mechanic in each mode are displayed on the display unit of the MUT 41.

The ECU 31 executes the SCR temperature increase / function confirmation routine shown in FIG. 4 at a predetermined control interval during operation of the engine 1. First, the ECU 31 determines whether or not a function confirmation mode start command is input from the MUT 41 in step S32. When the repair of the NOx purification system is completed based on the flashing of the SCR failure lamp 33, the mechanic connects the MUT 41 to the ECU 31 of the vehicle and inputs the start of the function confirmation mode in order to confirm the functional recovery of the NOx purification system. Based on the input, a command for starting the function confirmation mode is output from the MUT 41 to the ECU 31. In response to this, the ECU 31 makes a Yes determination in step S32 and proceeds to step S34, and displays the function confirmation mode on the display unit of the MUT 41. Show that it is running.
The overall function confirmation procedure is the same as the processing in steps S12 to S22 in the first embodiment. That is, manual regeneration is started in step S36, and when the catalyst temperature Tcat reaches the temperature rise end temperature T0 in step S38, manual regeneration is stopped in step S40. In this embodiment, ECU31 when performing the process of the above step S36-40 functions as a manual reproduction | regeneration means. Further, in step S42, the entire NOx purification system is set in a predetermined operating state. In step S44, it is determined whether or not the determination time TA has elapsed. In subsequent step S46, it is determined whether or not the detected value of the NOx sensor 36 has reached a normal level. judge.

If Yes is determined in step S46, the process proceeds to step S48, OK is displayed on the display unit of the MUT 41, and the routine is terminated after the display of the function confirmation mode is stopped in step S50. If YES is determined in step S44, the process proceeds to step S52 to display NG on the display unit of the MUT 41, and after executing the failure investigation mode in step S54, the routine is terminated. In this embodiment, ECU31 when performing the process of the above step S42-54 functions as a function confirmation means.
FIG. 5 is a flowchart showing a failure investigation routine executed by the ECU 31 in the failure investigation mode. The ECU 31 executes the process of step S54 according to the routine. First, in step S62, the fact that the failure investigation mode is being executed is displayed on the display unit of the MUT 41, and it is sequentially checked whether or not each component of the NOx purification system is a cause of failure by the processing from step S64.

In step S64, the inspection target and the inspection content are displayed on the display unit of the MUT 41, and an inspection preparation instruction is displayed as necessary. The inspection object is the configuration of the NOx purification system that is inspected in the current control cycle of the ECU 31, and the inspection content is a change in the specific operating state (operation stoppage) that is performed on the configuration by the various methods described above. Including). There are inspections that can be dealt with only by control of the ECU 31 such as correction of increase in the urea injection amount, and inspections that require preparation by a mechanic such as replacement of the SCR catalyst 20, and in the latter case, the mechanic performs it. The preparation work to be performed is displayed on the MUT 41 as an inspection preparation instruction.
Specifically, for example, when a urea injection system is inspected, the urea injection system is displayed as an inspection target, and a 1.5-fold increase correction of the urea injection amount is displayed as the inspection content. When the SCR catalyst 20 is inspected, the SCR catalyst 20 is displayed as an inspection object, the replacement of the SCR catalyst 20 is displayed as inspection contents, and an instruction to replace the SCR catalyst 20 with a new one as an inspection preparation instruction. Is displayed.

In subsequent step S66, it is determined whether or not the current inspection requires preparation by a mechanic. If the determination is No, the process proceeds to step S70. When the determination in step S66 is Yes, the process proceeds to step S68 and waits until preparation completion is input from the MUT 41. The mechanic performs inspection preparation in accordance with the preparation instruction displayed on the MUT 41, and inputs preparation completion to the MUT 41. When the determination in step S68 becomes Yes in response to the input, the ECU 31 proceeds to step S70.
In step S70 and subsequent steps, the temperature of the SCR catalyst 20 is raised by manual regeneration and an inspection is performed to determine whether or not the configuration of the NOx purification system to be inspected is a cause of failure. The basic processing contents are the same as those in steps S40 to S46, but are slightly different due to the difference in purpose between function confirmation and failure investigation.

That is, manual regeneration is started in step S70, and when the catalyst temperature Tcat reaches the temperature rise end temperature T0 in step S72, manual regeneration is stopped in step S74. In step S76, the entire NOx purification system is set in a predetermined operating state. Among the components of the NOx purification system, control based on the inspection content is executed for the configuration of the inspection target displayed in step S64.
For example, when the method of changing the operating state of the configuration to be inspected in the NOx reduction direction is adopted as the inspection method, the urea injection amount is corrected to increase 1.5 times in the inspection of the urea injection system, and the inspection of the SCR catalyst 20 is performed in the inspection. Since the SCR catalyst 20 has already been replaced, there is no change in control. Further, when the method of stopping the configuration of the inspection object is adopted as the inspection method, the urea injection amount is set to 0 in the inspection of the urea injection system, and the SCR catalyst 20 has already been extracted in the inspection of the SCR catalyst 20. There is no control change.

Thereafter, it is determined whether or not the determination time TA has elapsed in step S78, and the detection value of the NOx sensor 36 is determined in subsequent step S80. The processing content of step S80 also differs depending on the inspection method. When the method of changing the operating state of the configuration to be inspected in the NOx reduction direction is adopted as the inspection method, it is determined in step S80 whether or not the detected value of the NOx sensor 36 has reached a normal level. If the determination in step S80 is Yes, the configuration whose operating state has been changed is the cause of failure, and if the determination is No, it can be determined that the configuration is not the cause of failure.
Further, when the method of stopping the configuration of the inspection target is adopted as the inspection method, the NOx increase amount before and after the operation stop at step S80 (for example, immediately before making an NG determination at step S52 in the function confirmation mode from the current NOx amount). It is determined whether or not (the value obtained by subtracting the NOx amount) is less than a predetermined determination value. If the determination in step S80 is Yes, the configuration whose operating state has been changed is the cause of failure, and if the determination is No, it can be determined that the configuration is not the cause of failure.

Regardless of which inspection method is employed, if the determination time TA elapses in step S78 while the determination in step S80 is No, NG is displayed on the display unit of the MUT 41 in step S82, assuming that the configuration of the current inspection object is not the cause of failure. After the display, the process returns to step S64. In step S64, the processing of steps S64 to S80 is executed in the same manner as described above, with the configuration of the next NOx purification system as an inspection target.
Here, the inspection order of each component of the NOx purification system is determined in advance from the viewpoint of reducing the number of inspections and labor as much as possible. For example, the inspection order of each configuration is selected as an inspection target in order from the configuration with the highest occurrence rate of failure, or in order from the configuration that does not require or easy to prepare for inspection.

In the control cycle in which the configuration causing the failure is selected as the inspection target, Yes is determined in step S80 before the determination time TA has elapsed in step S78. At this time, the ECU 31 proceeds from step S80 to step S84, displays OK on the display unit of the MUT 41, and stops displaying the failure investigation mode in subsequent step S86. This OK display in step S84 means that the configuration of the cause of the failure has been specified, unlike step S48 which means that repair is completed.
In a succeeding step S88, a repair instruction for the identified failure cause configuration is displayed on the MUT 41, and then the routine is terminated. Specifically, when a urea injection system is specified as a cause of failure, a list of locations where the failure may occur in the system is displayed, and the SCR catalyst 20 is specified as the cause of failure by a method of stopping the operation state. When it is done, a repair instruction for mounting a new SCR catalyst 20 in place of the removed SCR catalyst 20 is displayed. Further, when the SCR catalyst 20 is specified as the cause of failure by the method of changing the operating state in the NOx reduction direction, no indication is given because the SCR catalyst 20 has already been replaced.

The mechanic performs the repair with reference to such a repair instruction, and inputs the start of the function confirmation mode to the MUT 41 after the repair is completed. Therefore, the ECU 31 starts the function confirmation mode again, and determines whether or not the function of the NOx purification system (more specifically, the function of the configuration identified and repaired as the cause of failure in the failure investigation mode) has been restored. The In addition, when the OK determination is made in the failure investigation mode by replacing the SCR catalyst 20 as described above, the function confirmation has been substantially completed, so that the subsequent execution of the function confirmation mode may be omitted. Good.
Thereafter, the same procedure as described above is repeated. If the result of the function confirmation mode is OK, the repair is completed. If the result is NG, a new configuration is identified as the cause of failure in the failure investigation mode, and after the repair by the mechanic is completed. Function confirmation is performed in the function confirmation mode.

The procedure of the function confirmation mode and the failure investigation mode executed by the ECU 31 after the repair of the NOx purification system will be described with reference to the time chart of FIG.
When the repair of the NOx purification system by the mechanic is completed and the function confirmation mode start command is input to the MUT 41, the function confirmation mode is started. First, the temperature of the SCR catalyst 20 is raised by manual regeneration of the DPF 18, and when the catalyst temperature Tcat reaches the temperature rise end temperature T0, the manual regeneration is stopped, and then it is determined whether the function has been recovered based on the NOx emission amount. . If an OK determination is made based on the detected value of the NOx sensor 36 before the determination time TA elapses, OK is displayed on the MUT 41 and the repair is completed, and the catalyst temperature Tcat gradually decreases as shown by a broken line. Further, when the determination time TA has passed without the detection value of the NOx sensor 36 becoming a normal level and an NG determination is made, the failure investigation mode is displayed on the MUT 41 after an NG display is made.

As a result, the function confirmation mode is shifted to the failure investigation mode, and the first inspection object and inspection contents are displayed on the MUT 41, and an inspection preparation instruction is displayed as necessary. FIG. 6 shows a case where a configuration requiring inspection preparation is selected at the beginning of the transition to the failure investigation mode, and inspection preparation is performed by a mechanic according to a preparation instruction. When the preparation for inspection is input to the MUT 41, manual regeneration is started, and the catalyst temperature Tcat once lowered as shown by the solid line rises again to reach the temperature rise end temperature T0, and the ECU 31 operates the configuration to be inspected. After the state is changed, it is determined whether or not the configuration is a cause of failure based on the NOx emission amount.
FIG. 6 shows a case where an NG determination is made that the configuration of the inspection target is not the cause of the failure, and the configuration of the NOx purification system that does not require preparation as the next inspection target is selected. At this time, the manual regeneration is started immediately after the inspection target and the inspection content are displayed on the MUT 41, and the operating state of the configuration of the inspection target is changed after the temperature of the SCR catalyst 20 is raised, and the determination based on the NOx emission amount is performed. Is called.

Also at this time, an NG determination is made, and the configuration of the NOx purification system that requires preparation is selected as the next inspection target, and a preparation instruction is displayed on the MUT 41 together with the inspection target and the inspection content. When an inspection preparation is performed by a mechanic in accordance with the preparation instruction and preparation completion is input, manual regeneration is started, and after the temperature of the SCR catalyst 20 is raised, the operation state of the configuration to be inspected is changed and a determination based on the NOx emission amount is performed. Is called. FIG. 6 shows a case where an OK determination (identification of the cause of failure) is made at this time, and a repair instruction for the identified configuration of the cause of failure is displayed on the MUT 41, and the failure investigation mode is terminated.
When the mechanic completes the repair with reference to the repair instruction, the function confirmation mode is started again based on the input to the MUT 41, and the recovery of the function of the NOx purification system is determined based on the NOx emission amount after the SCR catalyst 20 is heated by manual regeneration. Is done. FIG. 6 shows a case where an OK determination (repair completion) is made, and an OK display is made on the MUT 41 to complete the repair.

As described above, when an NG determination is made in the function confirmation mode after the repair of the NOx purification system, the configuration of the NOx purification system causing the failure is identified by the failure investigation mode, and after the repair with reference to the repair instruction for the configuration. Then, the function confirmation mode is executed again to determine the function recovery. Each time an NG judgment is made without recovering the function, a new failure cause is identified by the failure investigation mode. Therefore, even if multiple configurations cause the failure, appropriate repairs are performed individually. Finally, an OK determination is made in the function confirmation mode and the repair is completed.
As described above, according to the diagnostic apparatus for the NOx purification system of the present embodiment, manual regeneration of the DPF 18 is used for increasing the temperature of the SCR catalyst 20 in the function confirmation mode and the failure investigation mode. For this reason, as in the first embodiment, it is possible to prevent labor and time consumption due to traveling of the vehicle for raising the temperature, and to confirm the function of the NOx purification system easily and in a short time. In addition, since the function confirmation mode and failure investigation mode are executed under conditions of manual regeneration with little fluctuation in the catalyst temperature Tcat, it is highly accurate to determine whether the NOx purification system has recovered its function and to identify the cause of failure. Can be implemented.

In the present embodiment, when it is determined that the function of the NOx purification system has not recovered in the function confirmation mode, the operation state of each component of the NOx purification system is changed in the failure investigation mode and sequentially inspected. Accordingly, a preparation instruction for the mechanic is displayed on the MUT 41, thereby identifying the configuration of the NOx purification system causing the failure, and displaying a repair instruction for the configuration on the MUT 41.
As described above, when the function of the NOx purification system has not recovered after the repair, each component is automatically inspected sequentially in the failure investigation mode, so that even the unskilled mechanic can easily identify the cause of the failure. Moreover, since preparation instructions are displayed on the MUT 41 when preparations by the mechanic are required to change the operating state, it is possible to reduce mechanics' unnecessary labor due to inappropriate preparation.

As a result, even if the function is not recovered after repair of the NOx purification system, the cause of the failure can be identified easily and in a short time, thereby reducing the effort and time required for the entire repair of the NOx purification system including the identification of the cause of the failure. It can be greatly reduced.
In addition, since the MUT 41 conventionally used for failure diagnosis is used as an input device or a display device, it is possible to prevent an adverse effect of cost increase due to the addition of equipment.
This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in each of the embodiments described above, the exhaust purification device is configured by disposing the front-stage oxidation catalyst 17, DPF 18, injection nozzle 23, SCR catalyst 20, and rear-stage oxidation catalyst 21 from the exhaust upstream side of the engine 1, but is not limited thereto. Absent. For example, the front-stage oxidation catalyst 17 and the rear-stage oxidation catalyst 21 may be omitted, and the DPF 18 may be provided with an oxidation function. Even in this case, the same effects as those of the above embodiments can be obtained. Of course, the type of the engine 1 and the entire configuration of the NOx purification system are not limited to the above embodiment, and can be arbitrarily changed.

In the second embodiment, the program for executing the function confirmation mode and the failure investigation mode is stored on the ECU 31 side. However, these programs are stored on the MUT 41 side, and the MUT 41 is connected after the NOx purification system is repaired. The program may be read and executed on the ECU 31 side.
In the second embodiment, the function confirmation mode is used to confirm the function of the NOx purification system after the initial repair. When it is determined that the function has not been restored, the failure investigation mode is started. It is not limited to.
For example, the failure investigation mode may be executed before the initial repair. Specifically, when a failure of the NOx purification system is recognized based on the blinking of the SCR failure lamp 33, the failure investigation mode is started according to the routine of FIG. After the system configuration is specified and the initial repair is performed based on the repair instruction displayed on the MUT 41, the function confirmation mode may be started according to the routine of FIG. In this case, since the configuration of the cause of failure specified by the failure investigation mode can be repaired from the beginning, the labor and time required for repairing the NOx purification system can be further reduced.

1 engine 18 DPF (filter)
20 SCR catalyst (ammonia selective reduction type NOx catalyst)
23 Injection nozzle (reducing agent supply means)
31 ECU (failure diagnosis means, manual regeneration means, function confirmation means)
34 DPF over-deposition lamp (over-deposition notification means)
35 Playback start switch (function confirmation instruction means)
36 NOx sensor (NOx detection means)
41 MUT (diagnostic tool, function confirmation instruction means)

Claims (5)

An ammonia selective reduction type NOx catalyst that is disposed in an exhaust passage of an engine and selectively purifies NOx in exhaust gas by adding a reducing agent, and a reducing agent supply means for supplying the reducing agent to the ammonia selective reduction type NOx catalyst At least in the NOx purification system
A filter disposed upstream of the ammonia selective reduction type NOx catalyst in the exhaust passage and collecting particulates in the exhaust gas;
An over-deposit notification means for informing the particulate over-deposition to the filter;
When the regeneration start switch is operated by the driver in response to the notification from the overaccumulation notification means, manual regeneration is performed to forcibly remove the particulates collected by raising the temperature of the filter while the vehicle is stopped. Manual regeneration means to perform,
NOx detection means disposed downstream of the ammonia selective reduction type NOx catalyst in the exhaust passage;
After the repair of the NOx purification system based on the failure determination of the failure diagnosis means, when the function confirmation instruction means for instructing whether or not the function of the NOx purification system has been restored is operated, the notification by the over-deposition notification means Even when there is not, when the manual regeneration is performed by the manual regeneration means, when the downstream ammonia selective reduction type NOx catalyst is heated to at least the lower limit of activation temperature with the temperature increase of the filter by the manual regeneration, A NOx purification system diagnostic apparatus, comprising: function confirmation means for determining function recovery of the NOx purification system based on a detection value of the NOx detection means.   The function confirmation means causes the manual regeneration means to terminate manual regeneration when the temperature of the ammonia selective reduction type NOx catalyst reaches a temperature rise end temperature set in the vicinity of the activation lower limit temperature. The diagnostic apparatus for a NOx purification system according to claim 1. The function check instruction means is the regeneration start switch provided in the driver's seat of the vehicle,
The function confirmation means, when the regeneration start switch is operated, executes the function recovery determination following the manual regeneration only when there is no notification by the over-deposition notification means. 3. The diagnostic apparatus for the NOx purification system according to 1 or 2. The function check instruction means is a diagnostic tool connectable to the function check means,
3. The function confirmation means, when the start of a function confirmation mode is input by the diagnostic tool, executes the function recovery determination following the manual regeneration as the function confirmation mode. The diagnostic device for the NOx purification system described. In addition to the function confirmation mode, the function confirmation means sequentially changes the operating state of each component of the NOx purification system and prepares the diagnostic tool when manual preparation is required for changing the operating state. Is capable of executing a failure investigation mode that sequentially determines whether or not the configuration in which the operating state has been changed is a cause of failure of the NOx purification system based on the detection value of the NOx detection means,
The failure investigation mode is started at a timing after it is determined that the function of the NOx purification system has not recovered in the function confirmation mode or before the repair of the NOx purification system, and each configuration of the NOx purification system 5. The NOx purification system diagnosis apparatus according to claim 4, wherein a failure instruction is sequentially determined, and a repair instruction for the identified failure cause configuration is displayed on the diagnostic tool.

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