JP2009002268A - Diagnostic device of exhaust gas recirculating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diagnostic device of an exhaust gas recirculating device capable of precisely carrying out abnormality diagnosis of a control valve without being influenced by a deposit. <P>SOLUTION: The control valve 30 is provided in a recirculating channel 28 communicating an exhaust channel 26 of an internal combustion engine 1 and an air intake channel 16 with each other, and the control valve 30 is furnished with an opening detection sensor 50 to detect opening of a valve 32. Driving of the internal combustion engine 1 is stopped after regeneration of an exhaust emission control device 42 is finished (step 140) when the control valve 30 is opened (step 110), and whether the control valve 30 is abnormal or not is judged in accordance with opening detected by the opening detection sensor 50 by judging that the control valve is in a state of high temperatures and by judging that a diagnostic condition is established (steps 150-190) when the lapse of time until the driving of the internal combustion engine 1 is stopped after the regeneration of the exhaust emission control device 42 is finished is within a set period of time (step 140). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a diagnostic apparatus for an exhaust gas recirculation device for diagnosing an abnormality of a control valve provided in a recirculation flow path that communicates an exhaust flow path and an intake flow path of an internal combustion engine.

  Conventionally, when the valve body is driven by an actuator to control the valve opening, an opening degree detection sensor for detecting the opening degree of the valve body is provided, for example, the fully closed position where the valve body is abutted against the stopper is opened. It is controlled as a reference position for detection by the degree detection sensor. In that case, the detection value by the opening degree detection sensor at the fully closed position where the valve body is abutted against the stopper may change due to wear or temperature change.

  Therefore, as disclosed in Patent Document 1, the valve body is driven in the direction of the fully closed position by an actuator, such as a throttle valve, and the amount of change in the opening detected by the opening detection sensor every predetermined time is zero or If it is the opposite of the above, it is determined that the butting position has been reached. When the abutting position due to the rebound is detected, the opening position is set as a fully closed learning value.

Further, as disclosed in Patent Document 2, a lock current generated when the valve body abuts against the stopper by driving the actuator is detected, and the opening detected by the opening detection sensor when the lock current is detected is detected. The reference opening is updated.
JP 2005-188464 A Japanese Patent No. 3084929

  In such a conventional one, when the valve is a control valve provided in a recirculation flow path that connects the exhaust flow path and the intake flow path of the internal combustion engine, deposits are accumulated on the valve body and the stopper. When the deposit is accumulated and the actuator is driven to detect the abutting position by rebounding or the reference opening is detected by the lock current, updating according to the accumulated deposit is performed.

  Also, if an abnormality occurs in the opening detection sensor, when the valve body is driven in the fully closed direction, the opening change amount may be zero or reversed even if the valve body does not hit the stopper, or When the lock current is detected, the opening detected by the opening detection sensor may not be a normal value.

  Therefore, when learning and updating of the opening is performed at the fully closed position, it is difficult to distinguish whether the opening is updated due to deposit accumulation or the opening is updated due to an abnormality of the opening detection sensor. In addition, when the control valve drives the valve body with the spring biasing force and the driving force of the actuator, the valve body is not normally stopped when the abnormality occurs in the spring. It is difficult to distinguish whether it is due to an abnormality of the spring or whether it cannot be directly hit against the stopper due to the deposit. For this reason, there has been a problem that diagnosis of abnormality of the control valve is not easy.

  An object of the present invention is to provide a diagnostic device for an exhaust gas recirculation device that can accurately perform abnormality diagnosis of a control valve without being affected by deposits.

In order to achieve this problem, the present invention has taken the following measures in order to solve the problem. That is,
Exhaust gas for recirculating exhaust gas from the recirculation flow path to the intake flow path by providing a control valve in the recirculation flow path that connects the exhaust flow path and the intake flow path of the internal combustion engine In the gas recirculation device,
The control valve includes an opening detection sensor that detects the opening of the valve body,
Diagnostic condition establishment judgment means for judging whether or not a diagnostic condition in which operation of the internal combustion engine is stopped while the control valve is in a high temperature state is established,
An abnormality determination means for determining whether or not the control valve is abnormal based on the opening detected by the opening detection sensor when the diagnosis condition satisfaction determination means determines that the diagnosis condition is satisfied. An exhaust gas recirculation device diagnostic apparatus characterized by comprising:

  The diagnosis condition establishment determining means may determine that the control valve is in a high temperature state based on a time lapse of regeneration of the exhaust purification device provided in the exhaust flow path. At that time, the diagnosis condition satisfaction determining means is configured to stop the operation of the internal combustion engine after the regeneration of the exhaust purification device is finished, and to elapse time after the regeneration of the exhaust purification device is stopped until the operation of the internal combustion engine is stopped. May be determined that the control valve is in a high temperature state. Alternatively, the diagnosis condition establishment judging means may stop the operation of the internal combustion engine before the end of regeneration of the exhaust purification device, and the time elapses from the start of regeneration of the exhaust purification device until the operation of the internal combustion engine is stopped. When the set time is exceeded, it may be determined that the control valve is in a high temperature state.

  In addition, a reference fully closed position of the valve body is detected and stored by the opening degree detection sensor in the absence of deposit in advance, and the abnormality determining means returns the valve body of the control valve to the reference fully closed position. When the opening degree detection sensor does not detect that, the opening degree detection sensor may determine that it is abnormal. Further, the control valve includes a spring that urges the valve body in a valve closing direction, and the abnormality determination means determines that the spring is abnormal based on the opening of the valve body detected by the opening detection sensor. You may judge.

  According to the exhaust gas recirculation device diagnosis apparatus of the present invention, when the control valve is open, the opening degree detection sensor detects when a diagnosis condition is established in which the operation of the internal combustion engine is stopped while the control valve is in a high temperature state. Since it is determined whether or not the control valve is abnormal based on the opening, there is an effect that the abnormality diagnosis of the control valve can be accurately performed without being affected by the deposit.

  Further, if it is determined that the control valve is in a high temperature state based on the time elapsed for regeneration of the exhaust gas purification device provided in the exhaust flow path, it is easy to arrange a temperature sensor or the like on the control valve. It can be determined that the control valve is in a high temperature state with a simple configuration.

  When the opening detection sensor does not detect that the valve body of the control valve has returned to the reference fully closed position, the reference fully closed position of the valve body is detected and stored by the opening detection sensor in the absence of deposit in advance. By determining that the opening detection sensor is abnormal, it is possible to determine the abnormality easily and accurately. Further, when the control valve includes a spring, it is possible to determine the abnormality of the spring based on the opening of the valve body detected by the opening detection sensor.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an internal combustion engine using an exhaust gas recirculation system diagnostic apparatus according to an embodiment of the present invention. As shown in FIG. 1, the internal combustion engine 1 is a multi-cylinder, for example, a four-cylinder diesel engine in this embodiment, and a combustion chamber 8 is formed from a cylinder 2, a piston 4, and a cylinder head 6.

  The intake system of the internal combustion engine 1 includes an intake port 14 communicating with the combustion chamber 8 via an intake valve 12, an intake passage 16, a surge tank 18 that absorbs intake air pulsation, and a throttle valve 20 that adjusts the intake air amount. Is arranged. A fuel injection valve 21 for injecting fuel into the combustion chamber 8 is provided in the cylinder head 6.

  The exhaust system of the internal combustion engine 1 is provided with an exhaust port 24 and an exhaust passage 26 that communicate with the combustion chamber 8 via an exhaust valve 22. A recirculation flow path 28 that connects the intake flow path 16 and the exhaust flow path 26 is provided, and a control valve 30 is interposed on the intake flow path 16 side of the recirculation flow path 28.

  As shown in FIG. 2, the control valve 30 includes a butterfly valve body 32, and the valve body 32 is supported so as to be able to swing, and a biasing force by a spring 34 and a driving force by an actuator 36 such as a solenoid are generated. For example, in this embodiment, the valve body 32 is swung in the direction of closing the recirculation flow path 28 by the urging force of the spring 34, and the spring 34 is attached by the driving force of the actuator 36. The valve element 32 is swung in a direction that allows the recirculation flow path 28 to communicate with the predetermined opening degree against the force.

  Further, the valve body 32 is configured to be held at the fully closed position by the valve body 32 abutting against the stopper portions 38 and 40 at the position where the valve body 32 closes the recirculation flow path 28. Thus, the valve body 32 and the stopper parts 38 and 40 are provided in the recirculation flow path 28, and are arrange | positioned in the state exposed to exhaust gas.

  The exhaust passage 26 is provided with an exhaust purification device 42 in which an exhaust purification member is installed. In this embodiment, a diesel particulate filter (hereinafter referred to as DPF) 44 as an exhaust purification member is provided. Decorated.

  Exhaust gas contains many particulates mainly composed of carbon, which causes exhaust black smoke. In this embodiment, the DPF 44 is a honeycomb filter made of a porous ceramic or the like, and has a large number of passages along the longitudinal direction. An active oxygen release agent that holds and releases the held oxygen in the form of active oxygen when the surrounding oxygen concentration is lowered is supported. The DPF 44 is a known one that collects and burns such particulates.

  The detection system of the internal combustion engine 1 includes a throttle sensor 46 that detects the opening of the throttle valve 20, and the rotational speed of the internal combustion engine 1 according to the rotation of a distributor shaft (not shown) that rotates once by two rotations of a crankshaft (not shown). A rotation speed sensor 48 for detecting the opening, an opening detection sensor 50 for detecting the opening of the valve body 32 of the control valve 30, a differential pressure sensor 52 for detecting an exhaust gas pressure difference on both sides of the DPF 44, and an exhaust gas upstream of the DPF 44. An upstream exhaust temperature sensor 54 for detecting the temperature, a downstream exhaust temperature sensor 56 for detecting the exhaust gas temperature downstream of the DPF 44, and an air / fuel ratio sensor 58 for detecting the air / fuel ratio from the oxygen concentration of the exhaust gas downstream of the DPF 44 It is arranged.

  Each sensor is connected to an electronic control circuit 60. As shown in FIG. 1, the electronic control circuit 60 is configured as a logic operation circuit centering on a well-known CPU 62, ROM 64, RAM 66, etc. Are connected to each other via a common bus 70.

  The CPU 62 inputs and outputs input signals from the throttle sensor 46, the rotation speed sensor 48, the opening degree detection sensor 50, the differential pressure sensor 52, the upstream side exhaust temperature sensor 54, the downstream side exhaust temperature sensor 56, the air-fuel ratio sensor 58, and the like. The CPU 62 outputs a signal to the fuel injection valve 21, the control valve 30 and the like via the input / output circuit 68 based on these signals, the data in the ROM 64 and RAM 66 and the control program stored in advance. To do.

Next, diagnostic control processing performed in the electronic control circuit 60 described above will be described with reference to the flowchart of FIG.
An injection amount command value is calculated from a previously stored map or the like based on the throttle opening detected by the throttle sensor 46 and the rotation speed detected by the rotation speed sensor 48 as the operating state of the internal combustion engine 1. Based on this injection amount command value, fuel is injected from the fuel injection valve 21 and the internal combustion engine 1 is operated.

  At the same time, the exhaust gas recirculation rate is calculated from an exhaust gas recirculation rate map (not shown) based on the rotational speed and the injection amount command value as the operating state of the internal combustion engine 1. Based on the exhaust gas recirculation rate, the control amount of the control valve 30 is calculated, and the control valve 30 is driven and controlled to achieve the calculated exhaust gas recirculation rate.

  Further, the exhaust purification device 42 burns the collected particulates, but impurities (such as additives contained in oil and fuel) adhering to the particulates adhere as ash-like burning debris. If it is used for a period of time, clogging may occur, and the operating state of the internal combustion engine 1 may be adversely affected.

  Therefore, in the present embodiment, when the difference in exhaust gas pressure on both sides of the DPF 44 detected by the differential pressure sensor 52 becomes a predetermined value or more, the fuel injected from the fuel injection valve 21 is increased. As a result, the temperature of the exhaust gas discharged to the exhaust passage 26 through the exhaust port 24 becomes high, and unburned fuel is supplied to the DPF 44. This fuel burns in the DPF 44, the DPF 44 becomes high temperature, the deposit is burned, and the DPF 44 is regenerated.

  In some cases, the exhaust gas purification device 42 is equipped with a nitrogen oxide catalyst together with the DPF 44 or a three-way catalyst in a gasoline engine. The nitrogen oxide catalyst is a known catalyst that stores nitrogen oxides in exhaust gas at a lean air-fuel ratio and releases and reduces the nitrogen oxides stored at a rich air-fuel ratio.

  In this nitrogen oxide catalyst, sulfur oxide produced by the reaction of the sulfur component in the fuel with oxygen is occluded, and the purification efficiency of the catalyst is lowered. Therefore, the air-fuel ratio is temporarily made rich, and the sulfur oxide is removed by raising the temperature of the catalyst, so that the nitrogen oxide catalyst is regenerated. Also during the regeneration of the nitrogen oxide catalyst, the fuel injected from the fuel injection valve 21 is increased and the exhaust gas becomes high temperature.

  Then, the diagnostic control process is processed by interruption every predetermined time. First, the fuel injection amount injected from the fuel injection valve 21 is increased, and the regeneration control of the DPF 44 of the exhaust purification device 42 is started, and the regeneration is in progress. (Step 100). When the reproduction is not started (step 100: NO), the present control process is once ended, and it is determined whether or not the reproduction is started by an interruption process every predetermined time. The regeneration of the nitrogen oxide catalyst is not limited to the regeneration of the DPF 44.

  When regeneration is started and during regeneration (step 100: YES), it is determined whether or not the control valve 30 is opened (step 110). Whether the control valve 30 is open or not is determined by exhaust gas recirculation control by driving the actuator 36 and swinging the valve body 32 in the valve opening direction. Judgment is made based on whether the valve is opened each time.

  When the control valve 30 is not opened (step 110: NO), the diagnosis control process is temporarily terminated, and it is determined whether or not the control valve 30 is opened by interruption processing at regular intervals. If it is determined that the control valve 30 is opened (step 110: YES), it is determined whether or not the regeneration of the DPF 44 has ended normally (step 120).

  When regeneration of the DPF 44 is started and exhaust gas recirculation control is executed during regeneration and the control valve 30 is in an open state, the fuel injection amount from the fuel injection valve 21 is increased and the exhaust gas is heated to a high temperature. The exhaust gas is recirculated through the recirculation flow path 28 and the control valve 30 to the intake flow path 16.

  As shown in FIG. 4A, when the regeneration of the DPF 44 is started, the hot exhaust gas passes through the control valve 30, and the temperature inside the control valve 30 rises with time. When the high-temperature exhaust gas passes through the control valve 30, the deposit accumulated on the valve body 32 and the stopper portions 38 and 40 is exposed to the high-temperature exhaust gas and softens, and the deposit is softened. Peel from 40.

  If it is determined that the regeneration of the DPF 44 has been normally completed by the process of step 120 (step 120: YES), it is determined whether or not it is within a preset time from the completion of the regeneration of the DPF 44 (step 130).

  As shown in FIG. 4A, the internal temperature of the control valve 30 becomes the highest at the end of regeneration of the DPF 44, and the internal temperature decreases with the passage of time. Even after the regeneration is completed, the control valve 30 is in a high temperature state until a certain time, and the deposited deposit is softened and peeled off.

  If the time until the operation of the internal combustion engine 1 is stopped after the completion of the regeneration is short, the control valve 30 is still in a high temperature state, and the time during which the control valve 30 is still in a high temperature state after the regeneration is completed It is obtained by an experiment or the like and stored in advance in the ROM 64 or the like as a set time. Accordingly, the control valve 30 is in a high temperature state within a set time after the end of regeneration.

  If it is determined that it is within the set time after the end of regeneration (step 130: YES), it is determined whether or not the operation of the internal combustion engine 1 has been stopped (step 140). Whether or not the operation of the internal combustion engine 1 has been stopped is determined based on, for example, whether or not an ignition switch (not shown) has been turned off. Alternatively, the determination may be made based on the rotation speed detected by the rotation speed sensor 48 instead.

  When the operation of the internal combustion engine 1 is not stopped (step 140: NO), the processing after step 110 is repeated, and the regeneration is finished (step 120: YES) with the control valve 30 opened (step 110: YES). ), The process of determining whether or not it is within the set time after the end of reproduction is repeated (step 130). When the set time has elapsed since the end of the regeneration, it is determined that the temperature of the control valve 30 has decreased and deposits are being accumulated, and the control valve 30 is not diagnosed by executing the processing from step 140 onward. This control process is once terminated.

  When the operation of the internal combustion engine 1 is stopped (step 140: YES) within the set time after the end of regeneration (step 140: YES), it is determined by the opening degree detection sensor 50 that the diagnosis condition is satisfied. The opening degree of the control valve 30 is read (step 150). When the operation of the internal combustion engine 1 is stopped, the exhaust gas recirculation control is also stopped, the drive of the actuator 36 of the control valve 30 is also stopped, and the valve 32 is stopped by the urging force of the spring 34. It is swung so as to abut against the portions 38 and 40.

  Next, it is determined whether or not the detected opening of the control valve 30 is normal (step 160). The control valve 30 in a clean state in which no deposit is accumulated, for example, the opening degree detection sensor 50 in the fully closed state in which the valve body 32 of the control valve 30 in the state of a new vehicle immediately after manufacture hits the stopper portions 38 and 40. The detected reference fully closed position is stored in advance. The reference fully closed position is compared with the current detection value detected in step 150, and if the difference from the reference fully closed position is within a predetermined range, it is determined that the position is normal.

  When it is within the set time after the end of regeneration, the control valve 30 is still in a high temperature state, and the deposits accumulated on the valve body 32 and the stopper portions 38 and 40 are softened and peeled off, and are in a clean state. . Therefore, the valve body 32 can be abutted against the stopper portions 38 and 40 without being affected by deposit accumulation.

  If the difference between the reference fully closed position and the current detection value is within a predetermined range, the opening degree detection sensor 50 is not fully affected by deposit accumulation. It is determined that the closed position has been detected. If the detected opening is normal (step 160: YES), the detection value detected by the opening detection sensor 50 is updated as the fully closed position (step 170). For example, even if it is normal, the detected value may slightly deviate from the reference fully closed position due to wear, temperature change, or the like, and the fully closed position used in other control processing or the like is updated with the current detected value.

  On the other hand, when the difference between the reference fully closed position and the current detection value detected in step 150 is compared with the reference fully closed position by the process of step 160 and exceeds the predetermined range (step 160: NO). The opening degree detection sensor 50 determines that the opening degree detection sensor 50 cannot accurately detect the valve element 32 even though the valve body 32 is in contact with the stopper portions 38 and 40 without being affected by deposit accumulation. Notification that 50 is abnormal is made (step 180).

  After executing the processing of step 170 or step 180, it is determined whether or not the spring 34 is normal (step 190). Whether or not the spring 34 is normal is controlled based on the opening detected by the opening detection sensor 50 when the control valve 30 is closed after the operation of the internal combustion engine 1 is stopped, for example. The determination is made based on the amount of change in the opening of the valve element 32 when the valve 30 is closed, the position of the opening, and the like.

  The control valve 30 in a clean state in which no deposit is accumulated calculates the amount of change (oscillation speed) of the valve body 32 by the spring 34, and stores this in the ROM 64 or the like in advance as a reference amount of change in opening. . The stored reference opening change amount is compared with the currently calculated opening change amount, and it is determined that the spring 34 is normal when they are substantially equal. When the urging force of the spring 34 is reduced, the swing speed of the valve body 32 is reduced. Therefore, when the amount of change is smaller than the reference opening change amount, it is determined that the spring 34 is abnormal (step 190: NO). ). Then, the fact that the spring 34 is abnormal is notified (step 200).

  Alternatively, when the spring 34 is damaged, the valve body 32 cannot be abutted against the stopper portions 38 and 40, or the valve body 32 can be returned only partially in the valve closing direction. When it is detected from the detected opening position, it is determined that the spring 34 is abnormal (step 190: NO). Then, the fact that the spring 34 is abnormal is notified (step 200). In that case, since the abnormality of the opening degree detection sensor 50 is also detected at the same time by the execution of the processing of steps 160 and 180, it is preferable to notify at the same time.

  On the other hand, when it is determined that the regeneration of the DPF 44 is not completed by executing the process of step 120, it is determined whether or not the operation of the internal combustion engine 1 is stopped, for example, based on whether or not the ignition switch is turned off. (Step 210).

  When the operation of the internal combustion engine 1 is stopped (step 210: YES), it is determined whether or not a preset time stored in advance from the start of regeneration of the DPF 44 has elapsed (step 220). As shown in FIG. 4B, when regeneration of the DPF 44 is started, the exhaust gas temperature gradually rises, and the temperature inside the control valve 30 also rises accordingly. Even if the operation of the internal combustion engine 1 is stopped before the regeneration of the DPF 44 is completed, if the control valve 30 has been in a high temperature state until then, it has accumulated on the valve body 32 and the stopper portions 38 and 40. The deposit softens and peels off, resulting in a clean state.

  Therefore, if the set time has elapsed from the start of regeneration of the DPF 44 until the operation of the internal combustion engine 1 is stopped (step 220: YES), it is determined that the control valve 30 is in a high temperature state, and is described above. The processing after step 150 is executed to determine whether or not the control valve 30 is normal (steps 160 to 180) and whether or not the spring 34 is normal (steps 190 and 200). It should be noted that the set time may be determined in advance by experiments or the like, and this set time is different from the set time for the processing in step 130. If it is determined that the operation of the internal combustion engine 1 is not stopped by the execution of the process of step 210, the present control process is once ended and executed repeatedly at regular intervals.

  As described above, based on the opening degree detected by the opening degree detection sensor 50 when the diagnosis condition is established that the operation of the internal combustion engine 1 is stopped while the control valve 30 is in a high temperature state when the control valve 30 is open. Since it is determined whether or not the opening degree detection sensor 50 and the spring 34 of the control valve 30 are abnormal, the abnormality diagnosis of the control valve 30 can be performed accurately without being affected by the deposit.

  Further, since it is determined that the control valve 30 is in a high temperature state based on the time elapsed for regeneration of the exhaust purification device 42, the control valve 30 can be easily controlled with a simple configuration without arranging a temperature sensor or the like. It can be determined that the valve 30 is in a high temperature state.

  Furthermore, the reference fully closed position of the valve element 32 is detected and stored by the opening degree detection sensor 50 in the absence of deposit in advance, and the opening degree detection sensor 50 does not detect that the valve element 32 has returned to the reference fully closed position. Sometimes, when the opening degree detection sensor 50 determines that there is an abnormality, the abnormality can be determined easily and accurately. The abnormality of the spring 34 can also be easily determined based on the amount of change in the opening of the valve body 32 detected by the opening detection sensor 50.

  In this embodiment, it is determined that the control valve 30 is in a high temperature state when the internal combustion engine 1 is stopped within a set time after the regeneration of the DPF 44 is completed, or when the set time has elapsed after the regeneration of the DPF 44 is started It is determined whether or not the control valve 30 is normal. Not limited to this, the control valve 30 is in a high temperature state when the exhaust gas temperature detected by the upstream exhaust temperature sensor 54 and the downstream exhaust temperature sensor 56 is in a high temperature state. You may make it judge that it exists in a high temperature state. Alternatively, a temperature sensor that detects the temperature of the control valve 30 may be attached, and it may be determined that the control valve 30 is in a high temperature state based on the temperature detected by the temperature sensor.

  In the present embodiment, the execution of the processes of steps 100 to 140 and steps 210 and 220 serves as diagnostic condition establishment judgment means, and the execution of the processes of steps 150 to 200 serves as abnormality judgment means.

  The present invention is not limited to such embodiments as described above, and can be implemented in various modes without departing from the gist of the present invention.

It is a schematic block diagram of the internal combustion engine using the diagnostic apparatus of the exhaust gas recirculation apparatus as one embodiment of the present invention. It is an expansion schematic block diagram of the control valve of this embodiment. It is a flowchart which shows an example of the diagnostic control process performed in the electronic control circuit of this embodiment. It is a graph which shows the temperature change inside the control valve of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 4 ... Piston 6 ... Cylinder head 8 ... Combustion chamber 12 ... Intake valve 16 ... Intake flow path 18 ... Surge tank 20 ... Throttle valve 21 ... Fuel injection valve 22 ... Exhaust valve 26 ... Exhaust flow path 28 Recirculation flow path 30 Control valve 32 Valve body 34 Spring 36 Actuator 38, 40 Stopper 42 Exhaust gas purification device 44 DPF
46 ... Throttle sensor 48 ... Rotation speed sensor 50 ... Opening degree detection sensor 52 ... Differential pressure sensor 54 ... Upstream exhaust temperature sensor 56 ... Downstream exhaust temperature sensor 60 ... Electronic control circuit

Claims (6)

Exhaust gas for recirculating exhaust gas from the recirculation flow path to the intake flow path by providing a control valve in the recirculation flow path that connects the exhaust flow path and the intake flow path of the internal combustion engine In the gas recirculation device,
The control valve includes an opening detection sensor that detects the opening of the valve body,
Diagnostic condition establishment judgment means for judging whether or not a diagnostic condition in which operation of the internal combustion engine is stopped while the control valve is in a high temperature state is established,
An abnormality determination means for determining whether or not the control valve is abnormal based on the opening detected by the opening detection sensor when the diagnosis condition satisfaction determination means determines that the diagnosis condition is satisfied. A diagnostic apparatus for an exhaust gas recirculation device.   2. The diagnosis condition establishment determining means determines that the control valve is in a high temperature state based on a time lapse of regeneration of an exhaust purification device provided in the exhaust flow path. Diagnostic equipment for exhaust gas recirculation equipment.   The diagnosis condition establishment determining means is configured such that the operation of the internal combustion engine is stopped after the regeneration of the exhaust purification device is completed, and the time elapsed from the completion of the regeneration of the exhaust purification device until the operation of the internal combustion engine is stopped is a set time. The exhaust gas recirculation apparatus diagnosis apparatus according to claim 2, wherein the control valve determines that the control valve is in a high temperature state.   The diagnosis condition establishment determining means is configured such that the operation of the internal combustion engine is stopped before the regeneration of the exhaust purification device is finished, and the time elapsed from the start of regeneration of the exhaust purification device to the stop of the operation of the internal combustion engine is a set time. The exhaust gas recirculation apparatus diagnosis apparatus according to claim 2, wherein the control valve determines that the control valve is in a high-temperature state when the value exceeds. The reference fully closed position of the valve body is detected and stored by the opening degree detection sensor in the absence of deposit in advance,
The abnormality determining means determines that the opening degree detection sensor is abnormal when the opening degree detection sensor does not detect that the valve body of the control valve has returned to the reference fully closed position. The diagnostic apparatus for an exhaust gas recirculation device according to any one of claims 1 to 4. The control valve includes a spring that biases the valve body in a valve closing direction,
The exhaust according to any one of claims 1 to 5, wherein the abnormality determining means determines that the spring is abnormal based on an opening of the valve body detected by the opening detection sensor. Diagnostic device for gas recirculation device.

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