JP4098802B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine having an exhaust gas recirculation passage connecting an intake pipe and an exhaust pipe.

An intake pipe and an exhaust pipe of an internal combustion engine are connected by an exhaust gas recirculation passage, and an exhaust gas recirculation valve is provided in the exhaust gas recirculation passage so that a part of the exhaust gas is recirculated into the intake air in a predetermined operating state of the internal combustion engine. In general, control is performed to reduce the nitrogen temperature in the exhaust gas by lowering the combustion temperature by lowering the oxygen concentration in the intake air to slow the combustion. If this exhaust gas recirculation passage is clogged with foreign matter, or the exhaust gas recirculation valve becomes inoperable and exhaust gas cannot be recirculated into the intake air, the nitrogen oxides in the exhaust gas cannot be reduced, and the environment May be adversely affected. For this reason, it is necessary to quickly detect abnormalities in the exhaust gas recirculation function such as clogging of foreign substances in the exhaust gas recirculation passage or malfunction of the exhaust gas recirculation valve.

As an abnormality diagnosis of the exhaust gas recirculation function, for example, in JP-A-4-347354 (Prior Art 1), the exhaust gas recirculation valve is opened, and a part of the exhaust gas is recirculated into the intake air through the exhaust gas recirculation passage. The intake pipe pressure is stored, and then the exhaust gas recirculation valve is closed, and the difference between the intake pipe pressure and the stored intake pipe pressure when the exhaust gas recirculation is stopped is determined within a predetermined time. If it does not exceed, the exhaust gas recirculation function abnormality is judged.

In Japanese Patent Laid-Open No. 8-121260 (Prior Art 2), the exhaust gas recirculation valve is opened, secondary air is introduced into the exhaust pipe during the exhaust gas recirculation operation, and the output of the oxygen concentration detection means installed in the exhaust pipe is disclosed. Alternatively, abnormality diagnosis is performed based on the correction amount of the fuel amount correction means. Here, the secondary air means air introduced without passing through the intake pipe of the internal combustion engine. Normally, secondary air is introduced into the exhaust pipe when the internal combustion engine is cold-started. Combustion gas is combusted to promote catalyst activation, and exhaust gas purification can be performed at an early stage.

JP-A-4-347354 JP-A-8-121260

However, the abnormality diagnosis of the prior arts 1 and 2 is performed in the operating state of the internal combustion engine, and the abnormality diagnosis of the exhaust gas recirculation function is impossible when the internal combustion engine is stopped. Further, since the abnormality diagnosis is performed in the operation state of the internal combustion engine, there is a possibility that drivability, exhaust gas and the like are affected.

For example, when exhaust gas recirculation function abnormality diagnosis is performed at the time of deceleration fuel cut, the pressure in the intake pipe at the time of deceleration fuel cut is greatly lower than the atmospheric pressure, and if the exhaust gas recirculation valve is opened in this state, The pressure rises. When the exhaust gas recirculation passage is clogged with foreign matter or the exhaust gas recirculation valve does not open due to malfunction, the pressure change in the intake pipe becomes small, so that an abnormality in the exhaust gas recirculation function can be detected. However, when the exhaust gas recirculates from the state in which the engine brake is applied due to the deceleration fuel cut, the operation of the engine brake is reduced, which affects drivability.

In addition, in the prior art 1, the exhaust gas recirculation valve is closed for diagnosis of the exhaust gas recirculation function even though the exhaust gas recirculation valve should be kept open. Was given. In Prior Art 2, the exhaust gas containing the secondary air is recirculated through the exhaust gas recirculation passage during the operation of the internal combustion engine, so that the air-fuel ratio is changed and the fuel injection amount is corrected, which affects the exhaust gas. Was giving. In both of the prior arts 1 and 2, the abnormality diagnosis is not completed unless the predetermined operating condition of the internal combustion engine for performing the diagnosis of the exhaust gas recirculation function is continued for a predetermined time or more. As a result, the frequency of abnormality diagnosis is reduced. There was a problem. If the frequency of abnormality diagnosis is low, it takes time until an abnormality is detected after the abnormality occurs, and the operation time in an abnormal state with a bad exhaust gas state becomes long.

The present invention proposes a control device for an internal combustion engine that can improve such an inconvenience.

  An internal combustion engine control apparatus according to the present invention includes an exhaust gas recirculation passage connecting an intake pipe and an exhaust pipe of an internal combustion engine, an exhaust gas recirculation valve installed in the exhaust gas recirculation passage and controlling an exhaust gas recirculation amount, Exhaust gas recirculation valve control means for controlling the opening of the exhaust gas recirculation valve, secondary air introduction means for introducing secondary air into the exhaust pipe, intake pipe pressure detection means for measuring the pressure in the intake pipe, An internal combustion engine control apparatus comprising: a diagnostic unit for diagnosing an exhaust gas recirculation function through the exhaust gas recirculation passage, wherein the exhaust gas recirculation valve is opened by the exhaust gas recirculation valve control unit when the internal combustion engine is stopped In this state, the secondary air introduced by the secondary air introduction means flows into the intake pipe through the exhaust gas recirculation passage, and the diagnosis is performed based on the detection output of the intake pipe pressure detection means. Control apparatus for an internal combustion engine which stage is characterized in that for diagnosing the exhaust gas recirculation function.

In the control apparatus for an internal combustion engine according to the present invention, the exhaust gas recirculation function is diagnosed when the internal combustion engine is stopped. Therefore, the diagnosis frequency of the exhaust gas recirculation function is increased without adversely affecting the drivability and the exhaust gas, and the exhaust gas is exhausted. Abnormalities in the reflux function can be detected at an early stage.

Several embodiments of a control device for an internal combustion engine according to the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing Embodiment 1 of the control apparatus for an internal combustion engine according to the present invention. The control apparatus 100 for an internal combustion engine according to the first embodiment includes an internal combustion engine 1 mounted on an automobile, for example, and the control apparatus 50.

  The internal combustion engine 1 is a spark ignition internal combustion engine, and includes an engine body 10, an intake pipe device 20, an exhaust pipe device 30, and an exhaust gas recirculation device 40. The engine body 10 includes a cylinder 11, a piston 12, a crankshaft 14, an intake valve 15, an exhaust valve 16, a spark plug 17, and a crank angle sensor 18. The cylinder 11 and the piston 12 form a combustion chamber 13. The combustion chamber 13 sucks an air / fuel mixture through an intake valve 15 and an intake pipe device 20, and the mixture is ignited by an ignition plug 17 and burned. The exhaust gas is discharged through the exhaust valve 16 and the exhaust pipe device 30. The piston 12 is driven by the combustion of the air-fuel mixture in the combustion chamber 13 and rotates the crankshaft 14. A crank angle sensor 18 is attached to the crankshaft 14. The crank angle sensor 18 detects the rotation angle and rotation speed of the crankshaft 14.

  The intake pipe device 20 includes an intake pipe 21, an air cleaner 22, a throttle valve 23, a connecting portion 24, a fuel injection valve 25, an air flow sensor 26, a throttle position sensor 27, and an intake pipe pressure detecting means 28. . The intake pipe 21 communicates with the combustion chamber 13 through the intake valve 15. An air cleaner 22 is disposed in the air suction portion of the intake pipe 21. A throttle valve 23 is disposed in the intake pipe 21. The throttle valve 23 adjusts the amount of intake air taken into the combustion chamber 13 by adjusting the valve opening. The throttle valve 23 is a throttle valve mechanically connected to an accelerator pedal or an electronically controlled throttle valve that is electrically responsive to the accelerator pedal, and the valve opening degree is controlled in accordance with the depression amount of the accelerator pedal. The connection portion 24 is formed on the downstream side of the throttle valve 23, and the connection portion 24 is formed by partially expanding the diameter of the intake pipe 21 between the throttle valve 23 and the intake valve 15. The fuel injection valve 25 is disposed between the connection portion 24 and the intake valve 15. The fuel injection valve 25 injects a calculated amount of fuel into the intake air sucked into the combustion chamber 13 to obtain an air-fuel mixture.

  The air flow sensor 26 is disposed between the air cleaner 22 and the throttle valve 23 and detects the amount of air flowing from the air cleaner 22 to the throttle valve 23. The throttle position sensor 27 is attached to the throttle valve 23 and detects the valve opening degree of the throttle valve 23. The intake pipe pressure detection means 28 is disposed in the connection portion 24 and detects the intake pipe pressure P in the connection portion 24.

  The exhaust pipe device 30 includes an exhaust pipe 31, an exhaust gas purification catalyst 32, an exhaust gas sensor 33, and secondary air introduction means 35. The exhaust pipe 31 communicates with the combustion chamber 13 through the exhaust valve 16 and discharges the exhaust gas from the combustion chamber 13 through the exhaust gas purification catalyst 32. The exhaust gas sensor 33 is disposed in the exhaust pipe 31, detects the oxygen concentration in the exhaust gas, and the fuel control device corrects the fuel injection amount based on the detection result. The secondary air introduction means 35 has a secondary air introduction pipe 36 and a secondary air introduction pump 37 coupled to the secondary air introduction pipe 36. The secondary air introduction pump 37 introduces secondary air different from the air sucked into the intake pipe 21 into the exhaust pipe 31 through the secondary air introduction pipe 36 when the internal combustion engine 1 is cold-started. In this way, unburned gas is burned to promote catalyst activation, and the exhaust gas purifying action can be performed at an early stage. The secondary air introduction pipe 36 has a secondary air supply port 36 </ b> A communicating with the exhaust pipe 31.

  The exhaust gas recirculation device 40 includes an exhaust gas recirculation pipe 41 and an exhaust gas recirculation valve 43. The exhaust gas recirculation pipe 41 forms an exhaust gas recirculation passage 42 that connects the exhaust pipe 31 and the intake pipe 21. The exhaust gas recirculation pipe 41 has an exhaust gas inlet 41A that communicates with the exhaust pipe 31 and an exhaust gas recirculation port 41B that communicates with the connection portion 24 of the intake pipe device 20, and a part of the exhaust gas in the exhaust pipe 31 Is recirculated to the intake pipe 21. The exhaust gas recirculation valve 43 is disposed in the exhaust gas recirculation passage 42 near the exhaust gas recirculation port 41B. The exhaust gas recirculation valve 43 is an electric motor drive type valve, which is driven by, for example, a stepping motor, and adjusts the amount of exhaust gas to be recirculated by adjusting the valve opening degree by the stepping motor.

  The exhaust gas inlet 41A of the exhaust gas recirculation pipe 41 is disposed so as to face the secondary air supply port 36A of the secondary air introduction pipe 36 in the exhaust pipe 31, as shown in an enlarged view in FIG. Secondary air supplied from the secondary air supply port 36 </ b> A to the exhaust pipe 31 is taken into the exhaust gas recirculation passage 42 from the exhaust gas intake 41 </ b> A and supplied to the intake pipe 21. The configuration in which the secondary air supply port 36A and the exhaust gas intake 41A are opposed to each other in the exhaust pipe 31 is such that the secondary air supplied from the secondary air supply port 36A to the exhaust pipe 31 has a larger ratio. As a result, the exhaust gas is supplied to the intake pipe 21 from the exhaust gas inlet 41A through the exhaust gas recirculation passage 42.

  The control device 50 includes a control unit (ECU) 51. The control unit 51 is constituted by a microcomputer, for example. FIG. 3 is a functional block diagram of the control unit 51. The control unit 51 includes a diagnostic means 60 for the exhaust gas recirculation device. The control means 51 includes well-known fuel injection control means, ignition control means and the like in addition to the diagnostic means 60 of the exhaust gas recirculation device. The diagnostic means 60 of the exhaust gas recirculation device, the fuel injection control means, and the ignition control means are functional blocks that are executed by the CPU of the microcomputer that constitutes the control unit 51. The fuel injection control means calculates the fuel injection amount according to the intake air amount detected by the air flow sensor 26, the coolant temperature (not shown) of the internal combustion engine 1, and the like, and controls the fuel injection valve 25. The ignition control means calculates the ignition timing based on the rotation speed of the crankshaft 14 detected by the crank angle sensor 18 and the intake pipe pressure detected by the intake pipe pressure sensor 28 and controls the ignition timing of the ignition plug 17. To do.

  The exhaust gas recirculation apparatus diagnostic means 60 is provided with exhaust gas recirculation valve control means 61, secondary air introduction pump control means 62, electronic control throttle control means 63, control relay control means 64, and abnormality display means drive means 65. Is done. These exhaust gas recirculation valve control means 61, secondary air introduction pump control means 62, electronic control throttle control means 63, control relay control means 64, abnormality display means drive means 65 are output by the output of the diagnostic means 60 of the exhaust gas recirculation device. Be controlled. The exhaust gas recirculation valve control means 61, the secondary air introduction pump control means 62, the electronic control throttle control means 63, the control relay control means 64, and the abnormality display means drive means 65 are also the CPU of the microcomputer constituting the control means 51. Is a functional block executed by. When the throttle valve 23 is a throttle valve mechanically connected to an accelerator pedal, the electronic control throttle control means 63 is omitted.

  On the input side of the control unit 51, the battery power state detection means 71, the timer 72, and the ignition switch 73 are connected together with the crank angle sensor 18 and the intake pipe pressure detection means 28. The battery power supply state detection means 71 detects a power supply state such as a power supply voltage V of a battery power supply attached to the internal combustion engine 1. The timer 72 is incorporated in the control unit 51 and generates a clock representing the time. The ignition switch 73 is a switch that is turned on during operation of the internal combustion engine 1, and the spark plug 17 is supplied with power from a battery power source attached to the internal combustion engine 1 through the ignition switch 73.

  A control relay 75 and an abnormality display means 76 are connected to the output side of the control unit 51 together with the electronic control throttle valve 23, the secondary air introduction pump 37, and the exhaust gas recirculation valve 43. The control relay 75 is a switch for controlling the connection between the main power supply terminal of the control device 50 and the battery power supply attached to the internal combustion engine 1, and is controlled only during a predetermined abnormality diagnosis period when the internal combustion engine 1 is stopped. Power is supplied to the unit 51, the drive motor for the exhaust gas recirculation valve 43, the secondary air introduction pump 37, and the electronic control throttle valve 23, and an abnormality diagnosis for the exhaust gas recirculation function of the exhaust gas recirculation device 40 is executed. The abnormality display means 76 is means for displaying an abnormality in the exhaust gas recirculation function of the exhaust gas recirculation device 40. This abnormality display means 76 is composed of a display lamp or the like, and is turned on when there is an abnormality in the exhaust gas recirculation function of the exhaust gas recirculation device 40, and notifies the driver of the automobile that there is an abnormality in the exhaust gas recirculation device 40. The driver is urged to check and repair the exhaust gas recirculation device 40. A specific code for notifying the abnormality of the exhaust gas recirculation device 40 may be notified by blinking of the display lamp.

  The diagnostic means 60 of the exhaust gas recirculation device receives input signals from the ignition switch 73, the timer 72, the crank angle sensor 18, the intake pipe pressure detection means 28, and the battery power supply state detection means 71, and when the internal combustion engine 1 is stopped, the exhaust gas An abnormality diagnosis for the exhaust gas recirculation function of the recirculation device 40 is executed, and the exhaust gas recirculation valve control means 61, the secondary air introduction pump control means 62, the electronic control throttle valve control means 63, the control relay drive means 64, and the abnormality display means The drive means 65 is controlled.

  The control relay driving means 64 turns on the control relay 75 during a predetermined abnormality diagnosis period when the internal combustion engine 1 is stopped, and controls the control unit 51, the drive motor for the exhaust gas recirculation valve 43, 2 from the battery attached to the internal combustion engine 1, Power is supplied to the secondary air introduction pump 37 and the electronic control throttle valve 23, and an abnormality diagnosis for the exhaust gas recirculation function of the exhaust gas recirculation device 40 is executed. During the abnormality diagnosis period of the exhaust gas recirculation function, the exhaust gas recirculation valve control means 61 controls the exhaust gas recirculation valve 43 to be fully open, the secondary air introduction pump control means 52 drives the secondary air introduction pump 37, The electronic control throttle valve control means 64 controls the electronic control throttle valve 23 to be fully closed, and the abnormality display means driving means 65 notifies the abnormality by the abnormality display means 76 if there is an abnormality in the exhaust gas recirculation function.

  FIG. 4 shows a flowchart of the abnormality diagnosis operation of the exhaust gas recirculation function by the diagnostic means 60 of the exhaust gas recirculation device. With reference to FIG. 4, the abnormality diagnosis operation for the exhaust gas recirculation function of the exhaust gas recirculation device 40 will be described.

  The flowchart of FIG. 4 includes steps S101 to S113 between the start and the return. First, in step S101, it is determined whether or not the internal combustion engine 1 is in a stopped state. In this step S101, it is determined that the internal combustion engine 1 is in a stopped state by detecting that the rotation speed of the crankshaft 14 from the crank angle sensor 18 is zero, or that the ignition switch 73 is off. .

  The abnormality diagnosis period for the exhaust gas recirculation function of the exhaust gas recirculation device 40 is set, for example, to a period in which the internal combustion engine 1 is stopped immediately after the ignition switch 75 is turned off and until the control relay 75 is turned off. Each time the internal combustion engine 1 is stopped, an abnormality diagnosis is always executed during the period when the control switch 75 is on. Alternatively, the output of the timer 72 forces the control relay 75 to be forced when the internal combustion engine 1 is stopped and the power of the control device 50 is turned off at a predetermined time such as 2:00 am every day at midnight. It can also be turned on to perform abnormality diagnosis. Of course, in this case, if the internal combustion engine 1 is still in operation even at a predetermined time, the abnormality diagnosis for the exhaust gas recirculation function of the exhaust gas recirculation device 40 is not executed, and the time is changed to another time zone. Or postpone it on another day. Alternatively, in a hybrid vehicle, an idle stop vehicle, or the like, an abnormality diagnosis of the exhaust gas recirculation function may be performed while the internal combustion engine 1 is stopped while traveling or waiting for a signal.

  If it is determined in step S101 that the internal combustion engine 1 is stopped, an abnormality diagnosis of the exhaust gas recirculation function is performed, and the process proceeds to step S102. On the other hand, if it is determined in step S101 that the internal combustion engine 1 is not in a stopped state (in an operating state), the abnormality diagnosis of the exhaust gas recirculation function is not executed, and all the remaining steps of the program routine shown in FIG. Jump to finish.

  Next, in step S102, the exhaust gas recirculation valve control means 61 controls the exhaust gas recirculation valve 43 to fully open, and the process proceeds to step S103. Since the internal combustion engine 1 is in a stopped state and the intake pipe pressure P is substantially at atmospheric pressure, in step S103, the intake pipe pressure in a state close to atmospheric pressure is detected by the intake pipe pressure detecting means 28 and stored as P1. The process proceeds to step S104. In step S <b> 104, the secondary air introduction pump 37 is driven to introduce secondary air into the exhaust pipe 31. In step S104, since the exhaust gas recirculation valve 43 is already fully opened in step S102, the secondary air flows from the exhaust gas inlet 41A through the exhaust gas recirculation passage 42 into the connection portion 24 of the intake pipe 21. Is done.

  In the next step S105, it is determined whether or not the predetermined time tj has elapsed since the secondary air introduction pump 37 was driven. When it is determined that the predetermined time tj has elapsed, the process proceeds to step S106 for the first time. . Here, the predetermined time tj is a time until the intake pipe pressure P is sufficiently increased by the secondary air introduction means 35 when the exhaust gas recirculation passage 42 and the exhaust gas recirculation valve 43 are normal.

  In the next step S106, the intake pipe pressure detecting means 28 detects the intake pipe pressure P and stores it as P2, and the process proceeds to step S107. In step S107, an intake pipe pressure deviation PΔ (= P2−P1) is calculated and compared with a predetermined value α. If the exhaust gas recirculation passage 42 and the exhaust gas recirculation valve 43 are normal and the secondary air normally flows into the connection portion 24 of the intake pipe 21, the intake pipe pressure deviation PΔ exceeds the predetermined value α. It will be. However, when the exhaust gas recirculation passage 42 is clogged with some foreign matter, or when the exhaust gas recirculation valve 43 does not operate until fully open, the secondary air does not sufficiently flow into the connection portion 24 of the intake pipe 21. Therefore, the intake pipe pressure deviation PΔ is equal to or less than the predetermined value α. If the intake pipe pressure deviation PΔ is greater than the predetermined value α, the process proceeds to step S108. If the intake pipe pressure deviation PΔ is less than the predetermined value α, the process proceeds to step S110.

  As shown in FIG. 2, the configuration in which the exhaust gas inlet 41 </ b> A of the exhaust gas recirculation pipe 41 is disposed opposite to the secondary air supply port 36 </ b> A of the secondary air introduction pipe 36 is from the secondary air introduction pipe 36. The introduction of the secondary air into the exhaust gas recirculation pipe 41 is facilitated, resulting in a larger proportion of the secondary air being introduced into the exhaust gas recirculation pipe 41, and the comparison accuracy between the intake pipe pressure deviation PΔ and the predetermined value α It is effective to improve the above.

  When the routine proceeds to step S108, the intake pipe pressure deviation PΔ is larger than the predetermined value α, and therefore the exhaust gas recirculation function of the exhaust gas recirculation device 40 is determined to be normal in this step S108. From this step S108, the process proceeds to the next step S109, the normal time control is performed, and the process proceeds to step S112. Here, normal control means that, for example, when abnormality diagnosis of the exhaust gas recirculation function is executed immediately after the ignition switch 73 is turned off, normal processing before power off is executed, and finally the control relay 75 is turned on. This is a process such as turning off and turning off the power. When performing an abnormality diagnosis of the exhaust gas recirculation function at midnight, a process of turning off the power by turning off the control switch 75 is performed. Alternatively, it is possible to perform processing for storing the normality determination result for the exhaust gas recirculation function of the exhaust gas recirculation device 40 in the memory by the normal control.

  On the other hand, when the routine proceeds to step S110, since the intake pipe pressure deviation PΔ has not reached a sufficient predetermined value α, the exhaust gas recirculation function of the exhaust gas recirculation device 40 is determined to be abnormal in step S110. From this step S110, the process proceeds to step S111, the abnormal time control is performed, and the process proceeds to step S112. Here, the control at the time of abnormality is, for example, an abnormality display (abnormal lamp lighting or the like) by the abnormality display means 76, or a failure code of the exhaust gas recirculation device 40 is stored in the memory and the internal combustion engine 1 is operated next time. For example, the control of the exhaust gas recirculation device 40 is stopped.

  In step S112, the driving of the secondary air introduction pump 37 is stopped, and the process proceeds to step S113. In step S113, the exhaust gas recirculation valve 43 is controlled to be fully closed, and the program routine of FIG.

  FIG. 5 is a time chart of the abnormality diagnosis operation for the exhaust gas recirculation function of the exhaust gas recirculation device 40, FIG. 5 (a) shows the operation of the exhaust gas recirculation valve 43, and FIG. 5 (b) shows the secondary air introduction pump. FIG. 5C shows the change of the intake pipe pressure P, and FIG. 5D shows the operation of the abnormality display means 76 along the horizontal time axis T, respectively. The abnormality diagnosis operation for the exhaust gas recirculation function of the exhaust gas recirculation device 40 will be described with reference to FIG.

  At time T0 on the time axis T, abnormality diagnosis for the exhaust gas recirculation function of the exhaust gas recirculation device 40 is started. At this time T0, first, step S101 of FIG. 4 is executed to determine whether the internal combustion engine 1 is in a stopped state, and to determine whether to continue or cancel the abnormality diagnosis. At the next time point T1, step S102 of FIG. 4 is executed, and the exhaust gas recirculation valve 43 is controlled to be fully opened.

At time T3, step S103 of FIG. 4 is executed, the intake pipe pressure P is measured, and the intake pipe pressure P1 substantially equal to the atmospheric pressure is stored. At time T4, step S104 of FIG. 4 is executed, and the driving of the secondary air introduction pump 37 is started. The driving of the secondary air introduction pump 37 is continued for a predetermined time tj. At time T5 when a predetermined time tj has elapsed from time T4, step S106 of FIG. 4 is executed, the intake pipe pressure P is measured, and the intake pipe pressure P2 at that time is stored.

  Here, when the exhaust gas recirculation device 40 is normal, the intake pipe pressure P increases as shown by a solid line, and the intake pipe pressure P2 increases from P1 to a value greater than a predetermined value α. On the other hand, when the exhaust gas recirculation device 40 is abnormal, for example, when the exhaust gas recirculation valve 43 is fully closed and stuck, the air from the secondary air introduction pump 37 cannot flow into the connection portion 24 of the intake pipe 21. The intake pipe pressure P does not change and remains at the pressure P1 as indicated by the dotted line, and the intake pipe pressure deviation PΔ does not reach the predetermined value α.

  At time T6, step S107 in FIG. 4 is executed, the intake pipe pressure deviation PΔ (= P2−P1) is calculated, and compared with a predetermined value α to determine whether it is normal or abnormal. Here, when the exhaust gas recirculation function of the exhaust gas recirculation device 40 is determined to be normal, the abnormality display means 76 (for example, an abnormality display lamp or the like) remains off as indicated by a solid line, and does not change. When it is determined that the exhaust gas recirculation function of 40 is abnormal, it is turned on as indicated by a dotted line to notify the driver of the occurrence of abnormality in the exhaust gas recirculation device 40. Subsequent to time T6, steps S108 and S109 or S110 and S111 in FIG. 4 are executed.

  At the next time point T7, step S112 of FIG. 4 is executed, and the driving of the secondary air introduction pump 37 is stopped. At time T9, step S113 of FIG. 4 is executed, the exhaust gas recirculation valve 43 is controlled to be fully closed, and the abnormality diagnosis operation is terminated.

  As described above, in the control device 100 for the internal combustion engine of the first embodiment, the abnormality diagnosis for the exhaust gas recirculation function of the exhaust gas recirculation device 40 is performed when the internal combustion engine 1 is stopped, thereby improving drivability, exhaust gas, and the like. It is possible to detect an abnormality as early as possible after the occurrence of an abnormality without giving an adverse effect and increasing the frequency of abnormality diagnosis.

  In the first embodiment, as shown in FIG. 2, the exhaust gas intake 41A of the exhaust gas recirculation pipe 41 is arranged opposite to the secondary air supply port 36A of the secondary air introduction pipe 36. Even if the secondary air supply pipe 36 is connected to the exhaust gas recirculation pipe 41 at an acute angle near the exhaust gas inlet 41A of the exhaust gas recirculation pipe 41 as shown in FIG. , And the accuracy of comparison between the intake pipe pressure deviation PΔ and the predetermined value α can be improved.

Embodiment 2. FIG.
In the second embodiment, the throttle valve 23 is an electronically controlled throttle valve, and the electronically controlled throttle valve 23 is controlled to be fully closed when an abnormality is diagnosed with respect to the exhaust gas recirculation function of the exhaust gas recirculation device 40. In the second embodiment, the electronic control throttle valve control means 63 shown in FIG. 3 is used, and the electronic control throttle valve control means 63 fully closes the electronic control throttle valve 23 at the time of abnormality diagnosis. The other configuration is the same as that of the first embodiment.

  The secondary air that has flowed into the connection portion 24 of the intake pipe 21 through the exhaust gas recirculation passage 42 is controlled by fully closing the electronic control throttle valve 23 when diagnosing abnormality in the exhaust gas recirculation function of the exhaust gas recirculation device 40. However, since it is less likely to leak into the atmosphere through the gap of the electronic control throttle valve 23, the intake pipe pressure P increases and the abnormality diagnosis accuracy can be improved.

  FIG. 7 is a flowchart showing an abnormality diagnosis operation for the exhaust gas recirculation function of the exhaust gas recirculation device 40 according to the second embodiment. The flowchart of FIG. 7 is different from the flowchart of FIG. 4 in that a new step S114 is added between steps S102 and S103, and a new step S115 is added between steps S112 and S113. Is the same as the flowchart of FIG.

In the newly added step S114, the electronic control throttle valve 23 is controlled from the intermediate opening to the fully closed state, and then in step S103, the intake pipe pressure P1 is measured. In the subsequent step S104, the secondary air introduction pump 37 is turned on. To drive. Thereafter, abnormality diagnosis is performed from step S105 to step S111. After the drive of the secondary air introduction pump 37 is stopped in step S112, the electronically controlled throttle valve 23 is returned from the fully closed state to the intermediate opening degree in the added step S115. .

  FIG. 8 shows a time chart of an abnormality diagnosis operation for the exhaust gas recirculation function in the exhaust gas recirculation device 40 according to the second embodiment. FIG. 8A shows the operation of the exhaust gas recirculation valve 43, and FIG. The operation of the electronically controlled throttle valve 23, FIG. 8C shows the operation of the secondary air introduction pump 37, FIG. 8D shows the change in the intake pipe pressure P, and FIG. These operations are shown along the time axis T, respectively. The operation of the exhaust gas recirculation valve 43 in FIG. 8A, the operation of the secondary air introduction pump 37 in FIG. 8C, the change in the intake pipe pressure P in FIG. 8D, and the abnormality in FIG. The operation of the display means 76 is the same as that in FIG. 5, and the operation of the electronic control throttle valve 23 in FIG. 8B is added as compared with FIG.

  At time T2, step S114 of FIG. 7 is executed, and the electronic control throttle valve 23 is controlled from the intermediate opening to the fully closed state. Further, after the abnormality diagnosis is performed, at time T8, step S115 of FIG. 7 is executed to stop the fully closed drive control of the electronic control throttle valve 23, and the throttle valve 23 balances the opening side and the closing side urging means. Stop at an intermediate opening. The other operations at time points T0, T1, T3 to T7, and time point T9 are the same as those in FIG.

Embodiment 3 FIG.
In the third embodiment, the abnormality diagnosis operation for the exhaust gas recirculation function of the exhaust gas recirculation device 40 is stopped when the power state of the battery power supply attached to the internal combustion engine 1 has deteriorated to a predetermined level or less. is there. When the power supply state such as the power supply voltage V of the battery power supply has deteriorated to a predetermined level or less, an abnormality diagnosis for the exhaust gas recirculation function of the exhaust gas recirculation device 40 is executed when the internal combustion engine 1 is stopped. Since the battery performance may be further deteriorated by driving the air introduction pump 37 or the like, in the third embodiment, when the power supply state such as the power supply voltage V of the battery power supply is below a predetermined level, the exhaust gas recirculation device The abnormality diagnosis for the exhaust gas recirculation function of 40 is stopped, and problems such as the inability to start due to a decrease in battery performance when the internal combustion engine 1 is started next time are reduced. The other configuration is the same as that of the first embodiment.

  In the third embodiment, the battery power state detection means 71 shown in FIG. 3 is an indispensable means, and information (battery power supply voltage V or the like) obtained from the battery power state detection means 71 is used for the internal combustion engine 1. Detects whether the attached battery power supply is not deteriorated or fully charged.

  FIG. 9 is a flowchart showing an abnormality diagnosis operation for the exhaust gas recirculation function of the exhaust gas recirculation device 40 in the control apparatus for an internal combustion engine of the first embodiment. The flowchart in FIG. 9 is different from the flowchart in FIG. 4 only in that a new step S116 is added between step S101 and step S102, and is otherwise the same as the flowchart in FIG.

  In the newly added step S116, the state of the battery power supply attached to the internal combustion engine 1 is confirmed, and it is determined whether or not there is no problem even if an abnormality diagnosis is performed on the exhaust gas recirculation function of the exhaust gas recirculation device 40. If there is no problem with the battery power state, the abnormality diagnosis is continued and the process proceeds to the next step S102, and if it is detected that the battery power state is lowered, all the remaining steps of the program routine of FIG. Then, the abnormality diagnosis is stopped and terminated.

  The control apparatus for an internal combustion engine according to the present invention is used as a control apparatus for an internal combustion engine mounted on a vehicle such as an automobile.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows Embodiment 1 of the control apparatus of the internal combustion engine by this invention. FIG. 2 is an enlarged view of an exhaust gas intake portion according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration of a control device in the first embodiment. 3 is a flowchart showing a diagnostic operation of the exhaust gas recirculation device in the first embodiment. 3 is a time chart showing a failure diagnosis operation of the exhaust gas recirculation device in the first embodiment. FIG. 6 is an enlarged view of a modified example of the exhaust gas intake portion of the first embodiment. 7 is a flowchart showing an abnormality diagnosis operation of the exhaust gas recirculation device in Embodiment 2 of the control apparatus for an internal combustion engine according to the present invention. 6 is a time chart showing an abnormality diagnosis operation of the exhaust gas recirculation device in Embodiment 2. 9 is a flowchart showing an abnormality diagnosis operation of the exhaust gas recirculation device in Embodiment 3 of the control apparatus for an internal combustion engine according to the present invention.

Explanation of symbols

1: internal combustion engine, 10: engine body, 15: intake valve, 16: exhaust valve,
21: Intake pipe, 23: Throttle valve, 28: Intake pipe pressure detecting means, 31: Exhaust pipe,
35: secondary air introduction means, 36: secondary air introduction pipe, 36A: secondary air supply port,
40: exhaust gas recirculation device, 41: exhaust gas recirculation pipe, 41A: exhaust gas intake,
42: exhaust gas recirculation passage, 43: exhaust gas recirculation valve,
60: Abnormality diagnosis means for exhaust gas recirculation device 71: Battery power state detection means

Claims (7)

An exhaust gas recirculation passage connecting an intake pipe and an exhaust pipe of an internal combustion engine, an exhaust gas recirculation valve installed in the exhaust gas recirculation passage for controlling an exhaust gas recirculation amount, and an opening degree of the exhaust gas recirculation valve are controlled. Exhaust gas recirculation valve control means, secondary air introduction means for introducing secondary air into the exhaust pipe, intake pipe pressure detection means for measuring the pressure in the intake pipe, and exhaust gas recirculation function by the exhaust gas recirculation passage A control device for an internal combustion engine comprising diagnostic means for diagnosing
In a state where the exhaust gas recirculation valve is opened by the exhaust gas recirculation valve control means when the internal combustion engine is stopped, the secondary air introduced by the secondary air introduction means passes through the exhaust gas recirculation passage to the intake pipe. And the diagnostic means diagnoses the exhaust gas recirculation function based on the detection output of the intake pipe pressure detection means.   2. The control apparatus for an internal combustion engine according to claim 1, wherein a throttle valve is disposed in the intake pipe, the exhaust gas recirculation passage is connected to the intake pipe on the downstream side of the throttle valve, and the intake pipe pressure is detected. A control device for an internal combustion engine, wherein the device detects an intake pipe pressure downstream of the throttle valve.   3. The control apparatus for an internal combustion engine according to claim 2, wherein the throttle valve is an electronically controlled throttle valve, and the electronically controlled throttle valve is fully closed when the diagnosis means diagnoses the exhaust gas recirculation function. A control device for an internal combustion engine.   The control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the detection output of the intake pipe pressure detection means before the secondary air introduction means introduces the secondary air into the exhaust pipe. And the diagnostic means diagnoses the exhaust gas recirculation function based on a deviation from the detection output of the intake pipe pressure detection means after the secondary air introduction means introduces the secondary air into the exhaust pipe A control device for an internal combustion engine.   2. The control apparatus for an internal combustion engine according to claim 1, wherein a secondary air supply port of the secondary air introduction means and an exhaust gas intake port of the exhaust gas recirculation passage are opposed to each other in the exhaust pipe. A control apparatus for an internal combustion engine, characterized by being installed.   2. The control apparatus for an internal combustion engine according to claim 1, wherein a secondary air supply port of the secondary air introduction means is installed in the exhaust gas recirculation passage.   2. The control apparatus for an internal combustion engine according to claim 1, further comprising battery power state detection means for detecting a state of a battery power source attached to the internal combustion engine, wherein the power state of the battery power source is lowered to a predetermined level or less. A control device for an internal combustion engine, wherein the diagnosis of the exhaust gas recirculation function is not performed.

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