JP2002097995A - Abnormality diagnostic device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diagnose the abnormality of an air intake port closing valve without requiring new switches or sensors to detect the open/close of the air intake port closing valve. SOLUTION: The air intake port closing valve 24 is driven to the close position when a prescribed condition for executing the abnormality diagnosis is established during the engine is operated, then to the open position after a prescribed period of time elapses, and the existence of abnormality of the air intake port closing valve 24 is diagnosed based on the change of a value (air/ fuel ratio) detected by an air/fuel ratio sensor 32 just after that. If the air intake port closing valve 24 operates normally when it is driven to the open position from the close position, the wet fuel stuck to the air intake port closing valve 24 is sucked into a cylinder, so that the value (air/fuel ratio) detected by the air/fuel ratio sensor 32 is temporarily changed to the rich side. Therefore, if the change of the air/fuel ratio is not detected, it is judged that abnormality exists in the air intake port closing valve 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality diagnostic device for an internal combustion engine for diagnosing an abnormality in an intake port closing valve provided in an intake passage of the internal combustion engine.

[0002]

2. Description of the Related Art In recent years, lean burn engines have been put to practical use in which a lean air-fuel mixture thinner than the stoichiometric air-fuel ratio is burned for the purpose of improving fuel efficiency. In this lean burn engine, in order to stabilize the combustion state of the lean mixture, an intake port closing valve (such as a swirl control valve or a tumble control valve) is provided upstream of the intake port. By generating a swirl flow or a tumble flow, the gas flow in the cylinder is promoted to stably burn the lean air-fuel mixture.

The engine provided with the intake port closing valve is not limited to a lean burn engine, but is also applicable to an engine that controls the air-fuel ratio to stoichiometric (stoichiometric air-fuel ratio) for the purpose of improving torque and improving fuel efficiency. A valve may be provided.

[0004]

Incidentally, since the intake port closing valve is provided for each cylinder, even if the intake port closing valves of some cylinders become abnormal, the driver can take the following steps.
It is possible to continue driving without noticing the abnormality,
A cylinder having an abnormal intake port closing valve cannot stably burn a lean air-fuel mixture, which not only causes a decrease in engine output but also deteriorates exhaust emissions. Therefore, when the intake port closing valve becomes abnormal, it is desirable to detect it early and warn the driver.

Therefore, it is conceivable to diagnose whether or not the intake port closing valve is abnormal by detecting the opening and closing of the intake port closing valve with a switch or a sensor. However, in this configuration, it is necessary to newly provide a switch and a sensor for detecting opening and closing of the intake port closing valve, and there is a disadvantage that the cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and accordingly, it is an object of the present invention to provide a method of closing an intake port without providing a new switch or sensor for detecting the opening and closing of an intake port closing valve. It is an object of the present invention to provide an abnormality diagnosis device for an internal combustion engine that can diagnose the presence or absence of abnormality of a valve, and can realize an abnormality diagnosis function of an intake port closing valve while satisfying a demand for cost reduction.

[0007]

Generally, since the intake port closing valve is provided downstream of the fuel injection valve, when the intake port closing valve is in a closed state, a part of the injected fuel is supplied to the intake port. The wet fuel adheres to the surface of the shut-off valve as wet, and then when the intake port shut-off valve is opened, the wet fuel adhering to the intake port shut-off valve is drawn into the cylinder along with the flow of intake air. Immediately after the closing valve is opened, the air-fuel ratio temporarily shifts to the rich side.

Focusing on such characteristics, the internal combustion engine abnormality diagnosis apparatus according to claim 1 of the present invention uses the air-fuel ratio or the oxygen concentration of the exhaust gas of the internal combustion engine as a sensor used for abnormality diagnosis of the intake port closing valve. Of the detection value (air-fuel ratio) of the sensor immediately after driving the intake port closing valve from the closed position to the open position or from the open position to the closed position using a sensor (air-fuel ratio sensor or oxygen sensor) for detecting The abnormality diagnosis means diagnoses whether the intake port closing valve is abnormal based on the change or the change in the air-fuel ratio feedback correction amount.

For example, if the intake port closing valve operates normally when the intake port closing valve is driven from the closed position to the open position, the wet fuel attached to the intake port closing valve is sucked into the cylinder. , The detection value (air-fuel ratio) of the sensor temporarily changes to the rich side. Therefore, if the detected value (air-fuel ratio) of the sensor does not change to the rich side immediately after driving the intake port closing valve from the valve closing position to the valve opening position, it can be determined that the intake port closing valve is abnormal.
Immediately after the intake port closing valve is driven from the valve opening position to the valve closing position, the air-fuel ratio changes to the lean side by an amount corresponding to a part of the injected fuel adhering to the intake port closing valve as wet. Therefore, if the detected value (air-fuel ratio) of the sensor does not change to the lean side immediately after the intake port closing valve is driven from the open position to the closed position, it can be determined that the intake port closing valve is abnormal. At this time, the presence / absence of an abnormality of the intake port closing valve may be diagnosed using the air-fuel ratio feedback correction amount instead of the detection value (air-fuel ratio) of the sensor. Since the air-fuel ratio feedback correction amount is calculated based on the sensor detection value so that the air-fuel ratio detected by the sensor matches the target air-fuel ratio, there is a correlation between the sensor detection value and the air-fuel ratio feedback correction amount. Because there is.

In this case, an air-fuel ratio sensor (or an oxygen sensor) conventionally provided for air-fuel ratio feedback control can be used as a sensor used for abnormality diagnosis of the intake port closing valve. It is not necessary to provide a new switch or sensor for detecting the abnormality, and the abnormality diagnosis of the intake port closing valve can be performed while satisfying the demand for cost reduction.

Generally, when the intake port closing valve is driven from the closed position to the open position, the air-fuel ratio tends to change more than when the intake port is driven from the open position to the closed position.

Considering this characteristic, as in claim 2,
When the abnormality diagnosis execution condition is satisfied, the intake port closing valve is driven to the closed position, and after a lapse of a predetermined time, the intake port closing valve is driven to the open position, and a change in the detection value of the sensor immediately thereafter or the air-fuel ratio feedback is performed. It is preferable to diagnose whether there is an abnormality in the intake port closing valve based on a change in the correction amount. With this configuration, the abnormality diagnosis of the intake port closing valve can be performed more accurately.

Further, another control for causing a change in the air-fuel ratio during the execution of the abnormality diagnosis may be prohibited. Here, other controls that cause a change in the air-fuel ratio include, for example, EGR control (exhaust gas recirculation control), evaporative purge control (purge of fuel evaporative gas from the canister to the intake system), fuel injection amount correction, throttle opening There is a degree control. Temporarily prohibit these controls (fixed)
If the abnormality diagnosis of the intake port closing valve is performed, a change in the air-fuel ratio due to a factor other than the opening and closing of the intake port closing valve (change in the air-fuel ratio feedback correction amount) during the execution of the abnormality diagnosis
Does not occur, the change in the air-fuel ratio (change in the air-fuel ratio feedback correction amount) due to the opening and closing of the intake port closing valve can be accurately determined without being affected by other controls, and the abnormality diagnosis accuracy is improved. be able to. When an abnormality diagnosis of the intake port closing valve is performed based on a change in the detection value (air-fuel ratio) of the sensor, the air-fuel ratio feedback correction is prohibited and the air-fuel ratio feedback correction amount is fixed during the execution of the abnormality diagnosis. You may do it.

Further, in the system provided with ignition timing control means for stabilizing the engine speed during idle operation by feedback control of the ignition timing, the intake port closing valve is closed during idle operation. The abnormality of the intake port closing valve may be diagnosed based on a change in the ignition timing immediately after driving from the position to the valve opening position or from the valve opening position to the valve closing position. As described above, when the air-fuel ratio changes with the opening and closing of the intake port closing valve, the engine generated torque changes, and accordingly,
Since the idling rotational speed changes, the ignition timing feedback control works to correct the ignition timing. Therefore, the ignition timing changes according to the presence or absence of the abnormality of the intake port closing valve, similarly to the air-fuel ratio or the air-fuel ratio feedback correction amount, and the abnormality of the intake port closing valve can be diagnosed from the change of the ignition timing. .

In this case, a change in the detection value of the sensor (or a change in the air-fuel ratio feedback correction amount) is provided.
In addition, if the change in ignition timing is used as diagnostic data,
The reliability of the abnormality diagnosis of the intake port closing valve can be further improved.

Of course, the abnormality diagnosis of the intake port closing valve may be performed only from the change of the ignition timing as in the fifth embodiment. In this case, the same effect as in the first embodiment can be obtained.

According to a sixth aspect of the present invention, based on a change in the intake air amount or a change in the intake pipe pressure immediately after the intake port closing valve is driven from the closed position to the open position or from the open position to the closed position. The abnormality of the intake port closing valve may be diagnosed. That is, since the intake air amount and the intake pipe pressure change with the opening and closing of the intake port closing valve, the abnormality of the intake port closing valve can be diagnosed from the change of these detected values. Also in this case, the same effect as the first aspect can be obtained.

It is preferable to diagnose whether the intake port closing valve is stuck at the valve closing position or the valve opening position and does not operate normally. An abnormality diagnosis parameter (air-fuel ratio, ignition timing, intake air amount, etc.) due to the opening and closing of the intake port closing valve is greater when the intake port blocking valve is fixed at the valve closing position or at the valve opening position than when it is fixed at the intermediate position. ) Significantly appears, and abnormality diagnosis can be performed with high accuracy.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment (1)] An embodiment (1) in which the present invention is applied to a lean burn engine will be described below with reference to FIGS. First, a schematic configuration of the entire engine control system will be described with reference to FIGS. An air cleaner 13 is provided at the most upstream portion of an intake pipe 12 of an engine 11 which is an internal combustion engine, and an air flow meter 14 for detecting an intake air amount is provided downstream of the air cleaner 13. This air flow meter 1
Downstream of 4, a throttle valve 15 and a throttle opening sensor 16 for detecting the throttle opening are provided.

Further, on the downstream side of the throttle valve 15, a surge tank 17 is provided.
7, an intake pipe pressure sensor 18 for detecting an intake pipe pressure is provided. The surge tank 17 is provided with an intake manifold 19 for introducing air to each cylinder of the engine 11, and a fuel injection valve 20 for injecting fuel is attached to the intake manifold 19 of each cylinder.

As shown in FIG. 2, the intake passage of the intake manifold 19 of each cylinder downstream of the fuel injection valve 20 is branched into two intake passages 21 and 22.
1 and 22 are two intake ports 23 formed in each cylinder.
Respectively. One intake passage 22 for each cylinder
Inside, an intake port closing valve 24 such as a swirl control valve or a tumble control valve is arranged. The intake port closing valve 24 of each cylinder is connected via a common shaft 25 to an actuator 26 such as a solenoid or a step motor, and the actuator 26 drives the intake port closing valve 24 to open and close, so that the inside of each cylinder is The swirl or tumble flow intensity is controlled. An ignition plug 27 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in each cylinder is ignited by the ignition of each ignition plug 27.

The exhaust gas discharged from the exhaust port 28 of each cylinder passes through the exhaust manifold 29 and joins into one exhaust pipe 30. A catalyst 31 (see FIG. 1) such as a three-way catalyst for reducing CO, HC, NOx and the like in the exhaust gas is provided in the middle of the exhaust pipe 30, and an air-fuel ratio of the exhaust gas is provided upstream of the catalyst 31. An air-fuel ratio sensor 32 (or oxygen sensor) for detecting (or oxygen concentration) is provided.
Note that an air-fuel ratio sensor or an oxygen sensor may be provided downstream of the catalyst 31. Further, a water temperature sensor 33 for detecting a cooling water temperature and a crank angle sensor 34 for detecting an engine rotation speed are attached to a cylinder block of the engine 11.

These various sensor outputs are input to an engine control circuit (hereinafter referred to as "ECU") 35.
The ECU 35 is mainly composed of a microcomputer, executes various programs for engine control stored in a built-in ROM (storage medium), thereby executing fuel injection control and ignition control, and controlling the engine operating state. The swirl flow intensity or tumble flow intensity in each cylinder is controlled by controlling the operation of the actuator 26 in response to the opening and closing of the intake port closing valve 24.

Generally, as shown in FIGS. 1 and 2, the intake port closing valve 24 is provided downstream of the fuel injection valve 20, so that when the intake port closing valve 24 is in the closed state, the injection port is closed. Part of the fuel adheres to the surface of the intake port closing valve 24 as wet, and then, when the intake port closing valve 24 is opened, the wet fuel attached to the intake port closing valve 24 rides on the flow of intake air. Since it is sucked into the cylinder, the intake port closing valve 2
Immediately after opening the valve of No. 4, the air-fuel ratio temporarily shifts to the rich side.

Focusing on such characteristics, the ECU 35
3 drives the intake port closing valve 24 to the valve closing position when a predetermined abnormality diagnosis execution condition is satisfied during the operation of the engine by executing the abnormality diagnosis program of FIG. The closing valve 24 is driven to the open position, and the intake port closing valve 2 is determined based on the amount of change in the detection value (air-fuel ratio) of the air-fuel ratio sensor 32 immediately after that.
Diagnose 4 for abnormalities. The abnormality diagnosis function of the ECU 35 plays a role as abnormality diagnosis means referred to in the claims.

At the time of abnormality diagnosis, the intake port closing valve 24
If the intake port closing valve 24 operates normally when the valve is driven from the valve closing position to the valve opening position, the wet fuel adhering to the intake port closing valve 24 is drawn into the cylinder. The value (air-fuel ratio) temporarily changes to the rich side. If the intake port closing valve 24 is stuck at the closed position and does not move, the intake port closing valve 24 is actually opened even if the intake port closing valve 24 is driven to the open position during abnormality diagnosis. Therefore, the wet fuel adhering to the intake port closing valve 24 is not drawn into the cylinder, and the detection value (air-fuel ratio) of the air-fuel ratio sensor 32 does not shift to the rich side. Further, if the intake port closing valve 24 is stuck at the open position and cannot move, even if the intake port closing valve 24 is driven to the closed position, the intake port closing valve 24 is not actually closed. Therefore, no wet fuel is stored in the intake port closing valve 24, and no rich deviation of the air-fuel ratio due to the wet fuel occurs at the time of abnormality diagnosis. Therefore, the intake port closing valve 24
If the detected value (air-fuel ratio) of the air-fuel ratio sensor 32 does not change to the rich side immediately after the valve is driven from the valve closing position to the valve opening position, it can be determined that the intake port closing valve 24 is abnormal.

The ECU 35 executes the abnormality diagnosis program shown in FIG. 3 at a predetermined cycle in order to perform the abnormality diagnosis of the intake port closing valve 24 during the operation of the engine by the method described above. When this program is started, first, in step 101
It is determined whether or not the abnormality diagnosis execution condition is satisfied. Here, the abnormality diagnosis execution condition is determined based on, for example, the engine rotation speed, the vehicle speed, the cooling water temperature, and the like. The abnormality diagnosis execution condition is satisfied when the air-fuel ratio is stable in a steady operation state. If the abnormality diagnosis execution condition is not satisfied, the program ends without performing the subsequent processing.

On the other hand, if the abnormality diagnosis execution condition is satisfied, the routine proceeds to step 102, where the execution time counter is incremented, and the ECU 35 changes the intake port closing valve 24 from the ECU 35 until the value of the execution time counter reaches a predetermined value A. A valve closing signal is output to the actuator 26 to drive the intake port closing valve 24 to the valve closing position (Step 103,
104).

Thereafter, the value of the execution time counter becomes a predetermined value A.
Is reached, the ECU 35 outputs a valve-opening signal to the actuator 26 of the intake port closing valve 24 to drive the intake port closing valve 24 from the valve closing position to the valve opening position (steps 105 and 106), and the air-fuel ratio Sensor 32
Of the air-fuel ratio after the start of the valve-opening drive of the intake port closing valve 24 based on the output of step (10).
7). This accumulation of the change amount of the air-fuel ratio is continued until the value of the execution time counter reaches a predetermined value B (step 10).
8). As a result, the predetermined time after the start of the valve opening drive of the intake port closing valve 24 (the value of the execution time counter becomes the predetermined value A)
(A period until the predetermined value B is reached) is calculated.

Then, the value of the execution time counter becomes a predetermined value B
Is reached, the control of the intake port closing valve 24 is returned to the normal control (step 109), and the value of the execution time counter is cleared (step 110). In the next step 111, the change amount of the air-fuel ratio is compared with a judgment value C. If the change amount of the air-fuel ratio is larger than the judgment value C, the routine proceeds to step 112, where the intake port closing valve 24
Is determined to be normal, and the normal flag is set to ON.

On the other hand, if the change amount of the air-fuel ratio is equal to or less than the determination value C, the routine proceeds to step 113, where the intake port closing valve 2
It is determined that the operation 4 is abnormal, and the abnormality flag is set to ON. In this case, for example, a warning lamp (not shown)
Lights or flashes to warn the driver, and the ECU 3
The abnormality information is stored in a backup memory (not shown) in the storage unit 5.

It should be noted that the above-described abnormality diagnosis processing may be repeatedly executed during the operation of the engine, and when the determination of the presence of an abnormality is repeated a predetermined number of times, it may be finally determined that there is an abnormality.

An execution example of the abnormality diagnosis processing of the embodiment (1) described above will be described with reference to FIGS. FIG.
Shows the behavior at the time of normal operation, and FIG. 5 shows the behavior at the time of abnormal operation.

When the abnormality diagnosis execution condition is satisfied, the execution time counter is incremented, and the intake port closing valve 24 is driven to the closed position. Thereafter, when the value of the execution time counter reaches a predetermined value A, the intake port closing valve 24 is driven from the valve closing position to the valve opening position, and the accumulation of the change amount of the air-fuel ratio is started. The change amount of the air-fuel ratio during a predetermined time (a period from when the value of the execution time counter reaches the predetermined value A to the predetermined value B) after the start of the valve-opening drive is calculated. Then, when the value of the execution time counter reaches the predetermined value B, the change amount of the air-fuel ratio integrated so far is compared with the determination value C.

When the intake port closing valve 24 operates normally, when the intake port closing valve 24 is driven to the closed position, a part of the injected fuel is supplied to the intake port closing valve 2.
4, the wet fuel attached to the intake port closing valve 24 is drawn into the cylinder along with the flow of intake air when the intake port closing valve 24 is driven to the open position. Therefore, as shown in FIG. 4, immediately after the intake port closing valve 24 is opened, the air-fuel ratio temporarily changes to the rich side, and a rich peak occurs. For this reason, when the intake port closing valve 24 operates normally, the change amount of the air-fuel ratio for a predetermined time after the start of the valve opening drive of the intake port closing valve 24 becomes larger than the determination value C, and it is determined that the air-fuel ratio is normal. The normal flag is set to ON.

On the other hand, when the intake port closing valve 24 is stuck at the valve closing position or the valve opening position and does not move,
Since the opening degree of the intake port closing valve 24 does not change before and after the intake port closing valve 24 is driven to open, even if the intake port closing valve 24 is driven to open, as shown in FIG. No rich displacement occurs. For this reason, when the operation of the intake port closing valve 24 is abnormal, the change amount of the air-fuel ratio for a predetermined time after the start of the valve opening drive of the intake port closing valve 24 becomes smaller than the determination value C, and it is determined that there is an abnormality. The abnormality flag is set to ON.

In this case, since the air-fuel ratio sensor 32 conventionally provided for the air-fuel ratio feedback control can be used as a sensor used for abnormality diagnosis of the intake port closing valve 24, the opening / closing of the intake port closing valve 24 is detected. There is no need to provide a new switch or sensor for
An abnormality diagnosis of the intake port closing valve 24 can be performed while satisfying the demand for cost reduction.

In the embodiment (1) described above, the presence or absence of the abnormality of the intake port closing valve 24 is determined based on the change of the air-fuel ratio after the start of the valve opening drive of the intake port closing valve 24. Instead of the change in the air-fuel ratio, the presence or absence of the abnormality of the intake port closing valve 24 may be determined based on the change in the air-fuel ratio feedback correction amount. The air-fuel ratio feedback correction amount is calculated based on the detection value of the air-fuel ratio sensor 32 so that the air-fuel ratio detected by the air-fuel ratio sensor 32 matches the target air-fuel ratio. ) And the air-fuel ratio feedback correction amount.

In this embodiment (1), the intake port closing valve 24 is changed based on the change in the air-fuel ratio (or the change in the air-fuel ratio feedback correction amount) due to the wet fuel immediately after the opening operation of the intake port closing valve 24. To perform the abnormality diagnosis, if the air-fuel ratio changes due to a factor other than the opening and closing of the intake port closing valve 24 during the execution of the abnormality diagnosis, the accuracy of the abnormality diagnosis may be reduced due to the influence.

Therefore, another control that causes a change in the air-fuel ratio during the execution of the abnormality diagnosis may be prohibited. Here, other controls that cause a change in the air-fuel ratio include, for example, EGR control (exhaust gas recirculation control), evaporative purge control (purge of fuel evaporative gas from the canister to the intake system), fuel injection amount correction, throttle opening There is a degree control.
If these controls are temporarily prohibited (fixed) and the abnormality diagnosis of the intake port closing valve 24 is performed, a change in the air-fuel ratio due to factors other than the opening / closing of the intake port closing valve 24 during the abnormality diagnosis (the air-fuel ratio feedback correction amount) Change), the change in the air-fuel ratio (change in the air-fuel ratio feedback correction amount) due to the opening and closing of the intake port closing valve 24 can be accurately determined without being affected by other controls, and abnormality diagnosis is performed. Accuracy can be improved.

When the abnormality diagnosis of the intake port closing valve 24 is performed based on a change in the detection value (air-fuel ratio) of the air-fuel ratio sensor 32 as in the embodiment (1), the air-fuel ratio may be reduced during the execution of the abnormality diagnosis. It is also possible to prohibit the fuel ratio feedback correction and fix the air-fuel ratio feedback correction amount.

In this embodiment (1), the intake port closing valve 24 is driven from the valve closing position to the valve opening position immediately after driving the intake port closing valve 24 based on the change in the air-fuel ratio (or the air-fuel ratio feedback correction amount). Although the abnormality diagnosis of the closing valve 24 is performed, on the contrary, the change of the air-fuel ratio (or the air-fuel ratio feedback correction amount) immediately after the intake port closing valve 24 is driven from the open position to the closed position is determined. The abnormality diagnosis of the intake port closing valve 24 may be performed based on the change. Immediately after the intake port closing valve 24 is driven from the open position to the closed position, only a part of the injected fuel adheres to the intake port closing valve 24 as wet,
The air-fuel ratio changes to the lean side. Therefore, immediately after driving the intake port closing valve 24 from the open position to the closed position,
If the detection value (air-fuel ratio) of the air-fuel ratio sensor 32 does not change to the lean side, it can be determined that the intake port closing valve 24 is abnormal.

[Embodiment (2)] In the embodiment (2) shown in FIG. 6, the present invention is applied to a system provided with ignition timing control means for stabilizing the engine speed during idling by feedback control of the ignition timing. This is an embodiment of the present invention. When performing an abnormality diagnosis of the intake port closing valve 24 during the idling operation, if the air-fuel ratio changes with the opening and closing of the intake port closing valve 24, the engine generated torque changes and the idle rotation speed changes accordingly. Then, the ignition timing feedback control works to correct the ignition timing. Therefore, the ignition timing is controlled by the intake port closing valve 24 in the same manner as the air-fuel ratio and the air-fuel ratio feedback correction amount.
The ignition timing changes depending on the presence or absence of the abnormality, and the abnormality of the intake port closing valve can be diagnosed from the change in the ignition timing.

The abnormality diagnosis program of FIG. 6 executed in the embodiment (2) is the same as the abnormality diagnosis program of FIG.
a, 107a and 111a.
The processing of the other steps is the same as each step in FIG.

In the abnormality diagnosis program shown in FIG. 6, first, in step 101a, it is determined whether or not an abnormality diagnosis execution condition is satisfied, based on whether or not ignition timing feedback control during idling is being performed. During the execution of the ignition timing feedback control during operation, the abnormality diagnosis of the intake port closing valve 24 is performed.

When the abnormality diagnosis execution condition is satisfied, the intake port closing valve 24 is driven to the valve closing position, and after a predetermined time has elapsed, the intake port closing valve 24 is driven to the valve opening position as in the first embodiment (1). Steps 102 to 10
6). Then, the variation of the ignition timing for a predetermined time after the start of the valve opening drive of the intake port closing valve 24 (a period until the value of the execution time counter reaches the predetermined value B from the predetermined value A) is calculated (steps 107a and 108). ). The variation in the ignition timing may be calculated from the ignition timing control value calculated by the ECU 35.

Thereafter, the variation of the ignition timing is determined by a determination value D.
(Step 111a). If the variation in the ignition timing is larger than the determination value D, the process proceeds to step 112,
It is determined that the operation of the intake port closing valve 24 is normal, and the normal flag is set to ON.

On the other hand, if the variation of the ignition timing is equal to or less than the determination value D, the routine proceeds to step 113, where it is determined that the operation of the intake port closing valve 24 is abnormal, and the abnormality flag is set to ON.

In this case, the variation of the ignition timing used as the abnormality diagnosis data of the intake port closing valve 24 is determined by the ECU.
Since it can be calculated from the ignition timing control value calculated in 35, the intake port closing valve 24
The abnormality diagnosis of the intake port closing valve 24 can be performed without providing a new switch or sensor for detecting opening and closing of the intake port.

In this embodiment (2), the intake port closing valve 24 is controlled based on the variation of the ignition timing immediately after the intake port closing valve 24 is driven from the closed position to the open position.
However, conversely, the abnormality diagnosis of the intake port closing valve 24 is performed based on the variation of the ignition timing immediately after the intake port closing valve 24 is driven from the open position to the closed position. May be performed.

Further, the abnormality diagnosis method of the embodiment (2) may be combined with the abnormality diagnosis method of the embodiment (1). For example, during execution of the ignition timing feedback control during idling operation, the intake port closing valve 24
Is opened and closed, and both the variation of the ignition timing and the variation of the air-fuel ratio (or the air-fuel ratio feedback correction amount) for a predetermined time immediately after that are calculated, and the variation of the ignition timing and the air-fuel ratio (or the air-fuel ratio feedback correction) are calculated. Of the intake port closing valve 24 may be determined based on whether or not the amount of change in the amount is equal to or less than the determination values D and C. Alternatively, an abnormality diagnosis of the intake port closing valve 24 is performed by one of the abnormality diagnosis methods of the embodiments (1) and (2), and as a result, when it is determined that there is an abnormality, the other abnormality diagnosis method. An abnormality diagnosis may be performed, and as a result, when it is determined that there is an abnormality again, the abnormality may be finally diagnosed.

[Embodiment (3)] In the embodiment (3) shown in FIG. 7, focusing on the fact that the intake air amount changes with the opening and closing of the intake port closing valve 24, the opening of the intake port closing valve 24 is performed. It is determined whether or not the intake port closing valve 24 is abnormal based on the amount of change in the intake air amount immediately after the valve is driven.

The abnormality diagnosis program of FIG. 7 executed in the embodiment (3) is the same as the abnormality diagnosis program of FIG.
b, 107b, and 111b.
The processing of the other steps is the same as each step in FIG.

In the abnormality diagnosis program shown in FIG. 7, first, in step 101b, it is determined whether or not an abnormality diagnosis execution condition is satisfied, based on whether or not the operation state is such that the intake air amount is stable. When the operation amount is stable, the abnormality diagnosis of the intake port closing valve 24 is executed.

When the abnormality diagnosis execution condition is satisfied, the intake port closing valve 24 is driven to the valve closing position and the intake port closing valve 24 is driven to the valve opening position after a lapse of a predetermined time as in the first embodiment (1). Steps 101 to 10
6). Then, a change amount of the intake air amount for a predetermined time (a period until the value of the execution time counter reaches the predetermined value B from the predetermined value A) after the start of the valve opening drive of the intake port closing valve 24 is calculated (step 107b, 108). The amount of change in the amount of intake air may be calculated from the amount of intake air detected by the air flow meter 14.

Thereafter, the amount of change in the amount of intake air is compared with a judgment value E (step 111b). If the amount of change in the amount of intake air is larger than the judgment value E, the routine proceeds to step 112, where the intake port closing valve 24 Is determined to be normal, and the normal flag is set to ON.

On the other hand, if the variation of the intake air amount is equal to or smaller than the determination value E, the routine proceeds to step 113, where it is determined that the operation of the intake port closing valve 24 is abnormal, and the abnormality flag is turned on.
Set to.

In this case, the amount of change in the amount of intake air used as abnormality diagnosis data for the intake port closing valve 24 can be calculated from the detection value of the air flow meter 14 mounted for engine control. Similarly to the above, abnormality diagnosis of the intake port closing valve 24 can be performed without providing a new switch or sensor for detecting opening / closing of the intake port closing valve 24.

In this embodiment (3), the intake port closing valve 2 is determined based on the amount of change in the amount of intake air immediately after the intake port closing valve 24 is driven from the closed position to the open position.
The abnormality diagnosis of the intake port closing valve 24 is performed based on the change amount of the intake air amount immediately after the intake port closing valve 24 is driven from the open position to the closed position. Abnormality diagnosis may be performed.

Since the intake pipe pressure changes with the opening / closing of the intake port closing valve 24, the abnormality of the intake port closing valve 24 is detected by the intake pipe pressure sensor 18 instead of the change in the intake air amount. The detected change amount of the intake pipe pressure may be used.

The embodiment (3) described above may be implemented in combination with the embodiments (1) and (2).
Further, the abnormality diagnosis method of the present embodiment (3) may be applied to an engine (in-cylinder injection engine or the like) in which the fuel injection valve 20 is provided downstream of the intake port closing valve 24.

Each of the above-described embodiments (1) to (3)
In the above, when the predetermined abnormality diagnosis execution condition is satisfied, the intake port closing valve 24 is forcibly opened and closed to perform the abnormality diagnosis of the intake port closing valve 24. Intake port closing valve 24
When the opening and closing of the valve are switched, the intake port closing valve 2
4 may be performed.

Each of the above-described embodiments (1) to (3)
Now, the intake port closing valve 2
However, the present invention may be applied to a system in which an intake port closing valve is provided in an engine that controls the air-fuel ratio to stoichiometric (stoichiometric air-fuel ratio).

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire engine control system showing an embodiment (1) of the present invention.

FIG. 2 is a plan view of a main part of the engine.

FIG. 3 is a flowchart showing a flow of processing of an abnormality diagnosis program according to the embodiment (1).

FIG. 4 is a time chart showing the behavior of the abnormality diagnosis processing when the intake port closing valve operates normally.

FIG. 5 is a time chart showing the behavior of the abnormality diagnosis processing when the operation of the intake port closing valve is abnormal;

FIG. 6 is a flowchart showing a flow of processing of an abnormality diagnosis program according to the embodiment (2).

FIG. 7 is a flowchart showing a flow of processing of an abnormality diagnosis program according to the embodiment (3).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 14 ... Air flow meter, 15 ... Throttle valve, 17 ... Surge tank, 18 ... Intake pipe pressure sensor, 19 ... Intake manifold, 20 ... Fuel injection valve, 23 ... Intake port , 24 ...
Intake port closing valve, 26 ... actuator, 27 ...
Spark plug, 28 exhaust port, 30 exhaust pipe, 32 ...
Air-fuel ratio sensor, 35... ECU (abnormality diagnosis means).

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02D 41/14 310 F02D 41/14 310K 310D 310P 310B 41/16 41/16 Q 43/00 301 43/00 301B 301E 301U F02P 5/15 F02P 5/15 K F term (reference) 3G022 AA06 CA03 EA07 EA08 FA04 GA00 GA01 GA05 GA06 GA07 GA08 GA09 3G084 AA04 BA09 BA17 BA21 CA03 DA13 DA27 DA31 EB12 EB16 FA07 FA10 FA11 FA20 FA30 FA33 FA38 HA301 HA30 JA20 JB02 JB09 KA07 LA05 LB02 LC01 LC04 MA01 MA12 NA07 NB11 ND02 ND15 ND17 PA01Z PA07Z PA11Z PB03A PD09Z PE01Z PE03Z PE08Z PE09A

Claims (7)

[Claims] 1. An abnormality diagnosis device for an internal combustion engine for diagnosing an abnormality of an intake port closing valve provided in an intake passage of the internal combustion engine, comprising: a sensor for detecting an air-fuel ratio or an oxygen concentration of exhaust gas of the internal combustion engine; Based on a change in the detection value of the sensor or a change in the air-fuel ratio feedback correction amount immediately after driving the intake port closing valve from the valve closing position to the valve opening position or from the valve opening position to the valve closing position, An abnormality diagnosis device for an internal combustion engine, comprising: abnormality diagnosis means for diagnosing the presence or absence of an abnormality. 2. The abnormality diagnosis means drives the intake port closing valve to a valve closing position when an abnormality diagnosis execution condition is satisfied, and drives the intake port closing valve to a valve opening position after a lapse of a predetermined time. 2. The abnormality diagnosis device for an internal combustion engine according to claim 1, wherein the abnormality of the intake port closing valve is diagnosed based on a change in the detection value of the sensor or a change in the air-fuel ratio feedback correction amount immediately thereafter. 3. 3. The abnormality diagnosis device for an internal combustion engine according to claim 1, wherein the abnormality diagnosis unit prohibits another control that causes a change in the air-fuel ratio during the execution of the abnormality diagnosis. 4. An ignition timing control means for stabilizing an engine rotation speed during idle operation by feedback control of an ignition timing, wherein the abnormality diagnosis means changes a detection value of the sensor or an air-fuel ratio feedback correction amount at the time of abnormality diagnosis. In addition to changes in
4. The abnormality diagnosis apparatus for an internal combustion engine according to claim 1, wherein the abnormality of the intake port closing valve is diagnosed by using the change of the ignition timing as diagnostic data. 5. An abnormality diagnosis device for an internal combustion engine for diagnosing the presence or absence of an abnormality in an intake port closing valve provided in an intake passage of the internal combustion engine, wherein the engine speed during idling is stabilized by feedback control of ignition timing. A timing control means, based on a change in the ignition timing immediately after driving the intake port closing valve from the valve closing position to the valve opening position or from the valve opening position to the valve closing position during idling operation, whether or not the intake port valve closing valve is abnormal; An abnormality diagnosis device for an internal combustion engine, comprising: abnormality diagnosis means for diagnosing the abnormality. 6. An abnormality diagnosis device for an internal combustion engine for diagnosing an abnormality of an intake port closing valve provided in an intake passage of the internal combustion engine, comprising: a sensor for detecting an intake air amount or an intake pipe pressure; Abnormality diagnostic means for diagnosing the presence or absence of an abnormality in the intake port closing valve based on a change in the detection value of the sensor immediately after driving the valve from the closed position to the open position or from the open position to the closed position. An abnormality diagnosis device for an internal combustion engine. 7. The abnormality diagnosis unit according to claim 1, wherein the abnormality diagnosis unit diagnoses whether or not the intake port closing valve is stuck at a valve closing position or a valve opening position and does not operate normally.
An abnormality diagnosis device for an internal combustion engine according to any one of claims 6 to 6.