JP2000110594A - Abnormality diagnostic device of variable valve system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve abnormality diagnostic precision of a variable valve timing mechanism and prevent deterioration of drivability and emission with compatibility. SOLUTION: For example, whether an engine driving state is in the midway of deceleration or not is judged (step 101) as an abnormality diagnosis practice condition by taking notice of a fact that there is little influence on drivability and emission even when valve timing is forcibly changed at the time (during deceleration and acceleration) except for the time when an engine driving state is a steady state. Existence of abnormality of a variable valve timing mechanism is judged (steps 102-111) in accordance with whether variation of inlet pipe pressure at the time is higher than a judgement value or not by forcibly actuating the valve timing from the extreme delay angle position to a target spark- advance angle value for abnormality diagnosis when in the middle of deceleration. Consequently, it is possible to increase variation of inlet pipe pressure to use for abnormality judgement by setting the target spark-advance angle value for abnormality diagnosis without causing deterioration of drivability and emission at the time of abnormality diagnosis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality diagnosis apparatus for a variable valve system for diagnosing an abnormality in a variable valve mechanism for variably controlling at least one of a valve timing and a valve lift of an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, the number of internal combustion engines mounted on vehicles that employ a variable valve timing mechanism for the purpose of improving output, reducing fuel consumption, and reducing exhaust emissions has been increasing. In order to diagnose the abnormality of the variable valve timing mechanism, as shown in Japanese Patent Application Laid-Open No. 6-317118, the engine operating state is changed to a low rotation (1500 to 1500).
(2000 rpm) and in a steady state where the load is almost constant at a low load, the valve timing is forcibly changed, the change in the intake air amount at that time is detected, and the change in the intake air is compared with a determination value. There is one that diagnoses whether there is an abnormality in the variable valve timing mechanism.

[0003]

In the above publication, the valve timing is forcibly changed when the operating state of the engine is almost constant and the abnormality is diagnosed from the amount of change in the amount of intake air. , Forcibly changing the intake air amount in the steady state means forcibly changing the engine operating state that had been stable until then to a transient state, leading to deterioration in drivability and emission. become. On the other hand, if the amount of change in valve timing (change in intake air amount) is reduced to reduce the deterioration of drivability and emission during abnormality diagnosis, the difference between normal and abnormal times becomes smaller, and abnormality diagnosis is performed. Cannot be performed accurately. Therefore, in order to improve the abnormality diagnosis accuracy, it is necessary to increase the amount of change in valve timing (change in intake air amount) to some extent.

In recent years, some vehicles have adopted a variable valve lift mechanism for varying a valve lift amount. However, the situation of the variable valve lift mechanism has not changed. If the change in the intake air amount is reduced in order to reduce the influence on the abnormality, the abnormality diagnosis cannot be performed accurately. In the following description, the variable valve timing mechanism and the variable valve lift mechanism are collectively referred to as a “variable valve mechanism”.

Recently, an engine having a variable valve timing mechanism on both the intake side and the exhaust side, and an engine having both a variable valve timing mechanism and a variable valve lift mechanism have been considered. In these engines, it is conceivable that abnormality diagnosis is performed based on a change in the intake air amount. However, when abnormality diagnosis of one variable valve mechanism is performed and the other variable valve mechanism is operating, the other diagnosis is performed. The operation of the variable valve mechanism changes the intake air amount, making it impossible to perform accurate abnormality diagnosis.

The present invention has been made in view of these circumstances, and a first object of the present invention is to provide a system for diagnosing an abnormality in a variable valve mechanism based on a change in an intake parameter such as an intake air amount. The second object of the present invention is to provide a variable valve system abnormality diagnosis apparatus capable of performing abnormality diagnosis with high accuracy while reducing the influence on the engine and emission. It is an object of the present invention to provide an abnormality diagnosis device for a variable valve system that can accurately diagnose an abnormality of a variable valve mechanism based on a change in an intake parameter such as an intake air amount in an engine.

[0007]

According to a first aspect of the present invention, there is provided a variable valve system abnormality diagnosing apparatus for variably controlling a valve timing or a valve lift of an internal combustion engine. A detection value of the intake parameter detecting means when the intake air amount or the intake pipe pressure of the internal combustion engine is detected by the intake parameter detecting means, and the variable valve mechanism is forcibly operated using a control value for abnormality diagnosis. Based on a change in (intake air amount or intake pipe pressure), the abnormality diagnosis means diagnoses whether or not the variable valve mechanism is abnormal. At this time, the abnormality diagnosis means executes the abnormality diagnosis when the operation state of the internal combustion engine is other than the steady state.

When the operating state is other than the steady state, for example,
In a transient state such as an acceleration state or a deceleration state, intake parameters (intake air amount, intake pipe pressure) according to the operation state.
Therefore, during this period, even if the intake parameters are further changed for abnormality diagnosis, the influence on drivability and emissions is less than in the conventional case where the intake parameters are changed from the steady state. . Therefore,
If the abnormality diagnosis is performed when the operating state is other than the steady state, the change in the valve timing or the valve lift amount at the time of the abnormality diagnosis is increased to some extent while reducing the influence on the drivability and the emission and used for the abnormality diagnosis. The change in the intake parameter can be increased, and both the improvement of the abnormality diagnosis accuracy and the prevention of deterioration of drivability and emission can be achieved.

In an internal combustion engine having both a variable valve timing mechanism and a variable valve lift mechanism, when performing an abnormality diagnosis on the basis of a change in an intake parameter, the variable valve timing mechanism is used. An abnormality diagnosis is performed on one of the variable valve lift mechanisms based on a change in an intake parameter when one of the variable valve lift mechanisms is fixed and the other mechanism is forcibly operated using a diagnostic control value. It is good to With this configuration, in an internal combustion engine having both the variable valve timing mechanism and the variable valve lift mechanism, the change in the intake parameter due to the operation of the variable valve mechanism that does not perform the abnormality diagnosis is eliminated, and the variable valve that performs the abnormality diagnosis is used. Only the change of the intake parameter due to the operation of the mechanism can be taken out, and the abnormality diagnosis can be performed with high accuracy without being affected by the variable valve mechanism that does not perform the abnormality diagnosis at all.

According to a third aspect of the present invention, in an internal combustion engine having a variable valve mechanism (a variable valve timing mechanism and / or a variable valve lift mechanism) in both an intake valve and an exhaust valve, based on a change in an intake parameter. When performing the abnormality diagnosis, one of the intake-side variable valve mechanism and the exhaust-side variable valve mechanism was fixed, and the other variable valve mechanism was forcibly operated using the diagnostic control value. The abnormality of the other valve mechanism may be diagnosed based on the change of the intake parameter at that time. With this configuration, in an internal combustion engine having a variable valve mechanism for both the intake valve and the exhaust valve, a change in the intake parameter due to the operation of the variable valve mechanism on the valve side that does not perform the abnormality diagnosis is eliminated, and the abnormality is diagnosed on the valve side. Only the change of the intake parameter due to the operation of the variable valve mechanism can be taken out, and the abnormality diagnosis can be performed accurately without being affected by the variable valve mechanism on the valve side that does not perform the abnormality diagnosis.

Further, in an internal combustion engine equipped with a plurality of variable valve mechanisms according to the second and third aspects of the invention, the variable valve mechanism is operated when the operation state of the internal combustion engine is other than a steady state. It is preferable to perform abnormality diagnosis.
This makes it possible to achieve both prevention of deterioration of drivability and emission at the time of abnormality diagnosis and improvement of abnormality diagnosis accuracy, as in the first aspect.

In a variable valve system in which a variable valve mechanism is provided in each of the left and right banks of a V-type internal combustion engine, the variable valve mechanism of one of the left and right banks is fixed and the other is fixed. The abnormality diagnosis of the variable valve mechanism of the other bank is performed based on a change in the detection value of the intake parameter detection means when the variable valve mechanism of the other bank is forcibly operated using the control value for abnormality diagnosis. It is good to do. According to this configuration, in the variable valve system in which the variable valve mechanisms are provided in the left and right banks of the V-type internal combustion engine, the change in the intake parameter due to the operation of the variable valve mechanism on the bank that does not diagnose the abnormality is eliminated, and the abnormality diagnosis is performed by the bank. Only the change of the intake parameter due to the operation of the variable valve mechanism on the side can be taken out, and the abnormality diagnosis can be performed accurately without any influence from the variable valve mechanism on the bank side that does not diagnose the abnormality.

[0013]

[Embodiment (1)] An embodiment (1) of the present invention will be described below with reference to FIGS.
First, a schematic configuration of the entire system will be described with reference to FIG. The engine 11, which is an internal combustion engine, is a DOHC engine, and supplies power of a crankshaft 12 to an intake camshaft 13 and an exhaust camshaft 14 via a timing chain (not shown).
To the intake valve 1 by the respective camshafts 13 and 14.
5 and the exhaust valve 16 are driven to open and close.
The intake camshaft 13 is provided with a hydraulically driven variable valve timing mechanism 17 that adjusts the amount of advance of the intake camshaft 13 with respect to the crankshaft 12. Also, the intake camshaft 1
A camshaft sensor 23 is installed near 3 and a crankshaft sensor 24 is installed near the crankshaft 12.

In this case, the crankshaft sensor 24 generates N crankshaft phase detection pulse signals per rotation of the crankshaft 12, while the camshaft sensor 23 generates 2N crankshaft phase pulses per rotation of the intake camshaft 13. The camshaft phase detection pulse signals are generated. When the maximum advance amount of the intake camshaft 13 is θmax ° C. A, the number N of crankshaft phase detection pulse signals is set so that N <360 / θmax. Thereby, the actual valve of the intake valve 15 is determined by the relative rotation angle between the crankshaft phase detection pulse signal from the crankshaft sensor 24 and the camshaft phase detection pulse signal from the intake camshaft sensor 23 that is generated subsequently. The timing (actual advance angle of the intake camshaft 13) is calculated.

The cylinder block 1 of the engine 11
A cooling water temperature sensor 25 for detecting a cooling water temperature is attached to 1a, and an ignition plug 26 is attached to each cylinder to the cylinder head 11b.

On the other hand, an air cleaner 28 is provided at the most upstream portion of the intake pipe 27, and an air flow meter 29 for detecting an intake air amount is provided downstream thereof. A throttle valve 30 is provided downstream of the air flow meter 29, and the opening of the throttle valve 30 (throttle opening) is detected by a throttle sensor 31. An intake pipe pressure sensor 32 for detecting an intake pipe pressure is provided downstream of the throttle valve 30. Further, a fuel injection valve 34 is attached near the intake port 33 of each cylinder.

The outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as "ECU") 36. The ECU 36 is mainly composed of a microcomputer, and includes the crankshaft sensor 24 and the camshaft sensor 2.
The actual valve timing of the intake valve 15 is calculated based on the detection pulse signal from the engine 3 and the target valve timing of the intake valve 15 (the target advance amount of the intake camshaft 13) is calculated based on the output of various sensors for detecting the engine operating state. )
Is calculated.

The ECU 36 controls a hydraulic control valve (not shown) so that the actual valve timing of the intake valve 15 matches the target valve timing, and performs variable valve timing control (feedback control of the variable valve timing mechanism 17). Hereinafter, it is referred to as “VVT control”).

Further, the ECU 36 executes the abnormality diagnosis program shown in FIG. 2 at predetermined time intervals, so that the variable valve timing mechanism 17 can be operated in a state other than the steady state, for example, during deceleration.
Function as abnormality diagnosis means for performing abnormality diagnosis. Less than,
The processing contents of the abnormality diagnosis program of FIG. 2 will be described. When this program is started, first, in step 101, it is determined whether or not the vehicle is decelerating as an abnormality diagnosis execution condition. This determination is made based on, for example, whether or not fuel cut during deceleration is being performed. If it is determined in step 101 that the vehicle is not decelerating, the abnormality diagnosis execution condition is not satisfied, and the program ends without performing the subsequent abnormality diagnosis processing (steps 102 to 111).

On the other hand, if it is determined in step 101 that the vehicle is decelerating, the abnormality diagnosis execution condition is satisfied, and it is determined that even if the valve timing is forcibly changed, the influence on drivability and emission is small. Step 10
The second and subsequent abnormality diagnosis processes are performed as follows.

First, at step 102, the intake valve 15
Is forcibly returned to the most retarded position, and in the next step 103, the intake pipe pressure Pa when the valve timing of the intake valve 15 is at the most retarded position is read from the detection signal of the intake pipe pressure sensor 32. . In this case, the intake pipe pressure sensor 32 functions as intake parameter detection means described in the claims.

Thereafter, at step 104, the intake valve 1
The valve timing of No. 5 is forcibly advanced to a target advance value for abnormality diagnosis to change the intake pipe pressure. Thereafter, in step 105, the intake pipe pressure Pb detected by the intake pipe pressure sensor 32 is read, and in the next step 106,
It is determined whether or not the change amount (Pa-Pb) of the intake pipe pressure is equal to or greater than a determination value KP. At this time, a predetermined fixed value may be used as the determination value KP, or the determination value KP may be set by a map or a functional expression according to the engine operating state.

If the change in the intake pipe pressure (Pa-Pb)
Is smaller than the determination value KP, the routine proceeds to step 107, where it is determined whether or not a predetermined time T has elapsed. here,
The predetermined time T corresponds to the normal variable valve timing mechanism 17.
In order to take into account the operation delay of the valve, the change in the intake pipe pressure (P
The time is set slightly longer than the normal maximum time until a-Pb) becomes equal to or greater than the determination value KP. Therefore, if the variable valve timing mechanism 17 is normal, the change amount (Pa−Pb) of the intake pipe pressure within the predetermined time T is equal to the determination value K.
P or more.

Prior to the lapse of the predetermined time T, the above-described steps 105 and 106 are repeatedly executed each time it is determined that the change amount (Pa-Pb) of the intake pipe pressure is smaller than the determination value KP. If it is determined in step 106 that the change amount (Pa−Pb) of the intake pipe pressure has become equal to or greater than the determination value KP before the predetermined time T elapses, step 10 is performed.
The program proceeds to step 8, where it is determined that the variable valve timing mechanism 17 is normal, and the procedure proceeds to step 111 to return to the normal VVT control, and the program ends.

On the other hand, if the predetermined time T has elapsed without determining that the change amount (Pa-Pb) of the intake pipe pressure is equal to or more than the predetermined value KP in step 106, the variable valve timing mechanism 17 operates normally. If not, the process proceeds to step 109, where it is determined that the variable valve timing mechanism 17 is abnormal. In this case, in the next step 110, a warning lamp (not shown) is turned on or blinked to notify the driver of the abnormality of the variable valve timing mechanism 17, and then the process proceeds to step 111 to return to the normal VVT control. To end this program.

According to the embodiment (1) described above, during deceleration, attention is paid to the point that even if the valve timing is forcibly changed, the influence on drivability and emission is small, and the abnormality diagnosis is performed during deceleration. Because it is performed, it is possible to set the target advance angle value for abnormality diagnosis to be somewhat large without causing deterioration of drivability and emission at the time of abnormality diagnosis, and to increase the change amount of the intake pipe pressure used for abnormality diagnosis. It is possible to increase the difference between the amount of change in the intake pipe pressure between the normal state and the abnormal state. This allows
It is possible to improve abnormality diagnosis accuracy while preventing deterioration of drivability and emission during abnormality diagnosis.

In this embodiment (1), during deceleration,
Focusing on the fact that the intake pipe pressure is more susceptible to the valve timing change than the intake air amount and the change is large, the change in the intake pipe pressure is used as an intake parameter for abnormality diagnosis. And the difference in the amount of change in the intake pipe pressure at the time of abnormality can be made larger, and abnormality diagnosis can be performed more accurately.

However, according to the present invention, the amount of change in the intake air amount may be used as an intake parameter for abnormality diagnosis instead of the intake pipe pressure. Even in this case, if abnormality diagnosis is performed during deceleration, Since the target advance value for abnormality diagnosis can be set to some extent without deteriorating drivability and emission, it is possible to obtain a change amount of the intake air amount necessary for performing abnormality diagnosis.

In this embodiment (1), the determination during deceleration is made based on whether or not the fuel is cut during deceleration. However, the decrease in the accelerator opening, the decrease in the throttle opening, the fuel The determination may be made based on the decrease amount of the injection amount or the like.

[Embodiment (2)] In the embodiment (1), the abnormality diagnosis is performed during deceleration. However, in the embodiment (2) of the present invention shown in FIG. 3, the valve timing is adjusted during acceleration. Focusing on the fact that even a forced change has little effect on drivability and emission, abnormality diagnosis is performed during acceleration. Furthermore, in the present embodiment (2), during acceleration, attention is paid to the fact that the intake air amount is more susceptible to the valve timing change than the intake pipe pressure and the change amount is larger, and the intake air amount for abnormality diagnosis is taken. The amount of change in the amount of intake air is used as a parameter.

In the abnormality diagnosis program of FIG. 3 executed in the embodiment (2), first, at step 101a, it is determined whether or not acceleration is being performed as an abnormality diagnosis execution condition. This determination is made based on, for example, an increase in the accelerator opening, an increase in the throttle opening, an increase in the fuel injection amount, and the like.

If it is determined in step 101a that the vehicle is accelerating (the abnormality diagnosis execution condition is satisfied), it is determined that even if the valve timing is forcibly changed, the influence on the drivability and the emission is small, and in step 102, 1
In step 03a, the intake air amount Ga when the valve timing of the intake valve 15 is returned to the most retarded position is read from the detection signal of the air flow meter 29. In this case, the air flow meter 29 functions as an intake parameter detection unit described in the claims.

Thereafter, at step 104, the intake valve 1
The valve timing of No. 5 is forcibly advanced to the target advance value for abnormality diagnosis to change the intake air amount, and the intake air amount Gb detected by the air flow meter 29 is read in the next step 105a. Thereafter, in step 106a,
It is determined whether or not the amount of change in the intake air amount (Ga-Gb) is equal to or greater than a determination value KG.

If the change amount (Ga-Gb) of the intake air amount becomes equal to or larger than the determination value KG before the predetermined time T elapses, it is determined that the variable valve timing mechanism 17 is normal and the normal VVT control is performed. And the amount of change in the intake air amount (G
If the predetermined time T has elapsed without a-Gb) being equal to or greater than the determination value KG, it is determined that the variable valve timing mechanism 17 is abnormal, a warning is displayed, and the normal VVT control is returned (steps 107 to 111). .

In the embodiment (2) described above, the same effect as in the embodiment (1) can be obtained. In the above embodiment (2), the change amount of the intake air amount is used as the intake parameter for abnormality diagnosis, but the change amount of the intake pipe pressure may be used.

In each of the embodiments (1) and (2),
Variable valve timing mechanism 1 for intake valve 15
Although the present invention is applied to the abnormality diagnosis of No. 7, the present invention may be applied to abnormality diagnosis of a variable valve timing mechanism for an exhaust valve or a variable valve lift mechanism for changing a lift amount of an intake valve or an exhaust valve.

[Embodiment (3)] Next, an embodiment (3) of the present invention will be described with reference to FIG. In the present embodiment (3), a variable valve lift mechanism (not shown) for adjusting the lift amount of the intake valve 15 is provided in addition to the system configuration of the above-described embodiment (1).

As described above, in a system provided with both the variable valve timing mechanism 17 and the variable valve lift mechanism for one intake valve 15, when an abnormality diagnosis is performed based on a change in the intake air amount or the intake pipe pressure. For example, even if the variable valve lift mechanism is forcibly controlled to the target lift value for abnormality diagnosis, the variable valve timing mechanism 1
7 operates, the intake air amount and the intake pipe pressure fluctuate due to the influence, and accurate abnormality diagnosis cannot be performed.

Therefore, in this embodiment (3), the abnormality diagnosis program shown in FIG.
An abnormality diagnosis of the variable valve lift mechanism in the system including the variable valve timing mechanism 17 and the variable valve lift mechanism is performed as follows.

First, in step 201, it is determined whether or not there is a request for abnormality diagnosis of the variable valve lift mechanism. If there is no request for abnormality diagnosis of the variable valve lift mechanism, this program is terminated. Thereafter, when an abnormality diagnosis request of the variable valve lift mechanism is issued, the process proceeds to step 202, in which the variable valve timing mechanism 17 for which abnormality is not diagnosed is fixed at the current advance value, and the intake air amount by the operation of the variable valve timing mechanism 17 is set. And fluctuations in the intake pipe pressure.

Thereafter, the routine proceeds to step 203, where abnormality diagnosis of the variable valve lift mechanism is executed. This abnormality diagnosis is
For example, the presence or absence of an abnormality is determined by forcibly changing the lift amount of the intake valve 15 to a target lift value for abnormality diagnosis and comparing the amount of change in the intake air amount or intake pipe pressure at that time with the abnormality determination value. I do. After abnormality determination, step 20
Then, the procedure proceeds to step 4, where the abnormality diagnosis is terminated and the variable valve lift mechanism is returned to the normal control. In the next step 205, the variable valve timing mechanism 17 is released to return to the normal VVT control, and this program is terminated.

In this manner, fluctuations in the amount of intake air and the intake pipe pressure caused by the operation of the variable valve timing mechanism 17 that does not diagnose an abnormality are eliminated, and the amount of intake air or the amount of air that reflects only the operation of the variable valve lift mechanism that diagnoses an abnormality is eliminated. An abnormality diagnosis can be made based on the amount of change in the intake pipe pressure. As a result, in a system having both the variable valve timing mechanism 17 and the variable valve lift mechanism, it is possible to perform accurate abnormality diagnosis.

When performing an abnormality diagnosis of the variable valve timing mechanism 17, the variable valve lift mechanism may be fixed. In the above embodiment (3), the present invention is applied to a system in which the intake valve 15 has both the variable valve timing mechanism 17 and the variable valve lift mechanism. However, the exhaust valve 16 has the variable valve timing mechanism and the variable valve lift mechanism. It is also applicable to systems with both mechanisms.

[Embodiment (4)] Next, an embodiment (4) of the present invention will be described with reference to FIG. In the present embodiment (4), an exhaust-side variable valve timing mechanism (not shown) for changing the valve timing of the exhaust valve 16 is provided in addition to the system configuration of the embodiment (1).

Even in a system in which both the intake valve 15 and the exhaust valve 16 are provided with a variable valve timing mechanism, when the abnormality is diagnosed based on a change in the intake air amount or the intake pipe pressure, the variable valve on the valve side which does not perform the abnormality diagnosis If the timing mechanism is operating, the intake air amount and the intake pipe pressure fluctuate due to the effect, and accurate abnormality diagnosis cannot be performed.

Therefore, in this embodiment (4), the abnormality diagnosis program shown in FIG.
An abnormality diagnosis in a system having a variable valve timing mechanism in both the intake valve 15 and the exhaust valve 16 is performed as follows.

First, at step 301, it is determined whether or not there is an abnormality diagnosis request for the intake side variable valve timing mechanism 17, and if there is an abnormality diagnosis request for the intake side variable valve timing mechanism 17, the process proceeds to step 302. The exhaust-side variable valve timing mechanism that does not diagnose abnormalities is fixed to eliminate fluctuations in the amount of intake air and the intake pipe pressure due to the operation of the exhaust-side variable valve timing mechanism. Perform diagnostics.
This abnormality diagnosis is performed when the intake side variable valve timing mechanism 17 is forcibly advanced from the most retarded position to the target advance value for abnormality diagnosis, as in the embodiment (1) or (2). An abnormality diagnosis is performed based on a change in the air amount or a change in the intake pipe pressure. After the abnormality is determined, the routine proceeds to step 304, where the abnormality diagnosis is terminated and the intake-side variable valve timing mechanism 17
Is returned to the normal VVT control, and in the next step 305, the fixing of the exhaust side variable valve timing mechanism is released to return to the normal VVT control, and this program ends.

On the other hand, if there is no request for abnormality diagnosis of the intake-side variable valve lift mechanism 17 in step 301, the process proceeds to step 306, and it is determined whether or not there is a request for abnormality diagnosis of the exhaust-side variable valve timing mechanism. If there is a request for abnormality diagnosis of the exhaust-side variable valve timing mechanism, the intake-side variable valve timing mechanism 17 that does not perform abnormality diagnosis is fixed, and fluctuations of the intake air amount and the intake pipe pressure due to the operation of the intake-side variable valve timing mechanism 17 are reduced. It is lost (step 307). Thereafter, an abnormality diagnosis of the exhaust-side variable valve timing mechanism is performed in the same manner as the intake side (step 308). After the abnormality is determined, the abnormality diagnosis is terminated and the exhaust-side variable valve timing mechanism is returned to the normal VVT control (step 308). 309), the fixing of the intake side variable valve timing mechanism 17 is released, and the control returns to the normal VVT control (step 310), and this program ends.

In this way, the operation of the variable valve timing mechanism on the valve side that does not diagnose the abnormality does not cause a change in the intake air amount or the intake pipe pressure, and only the operation of the variable valve timing mechanism on the valve side that diagnoses the abnormality is reflected. Anomaly diagnosis can be performed based on the amount of change in the intake air amount or the amount of change in the intake pipe pressure, and accurate abnormality diagnosis can be performed even in a system having a variable valve mechanism for both the intake valve and the exhaust valve. It becomes possible.

In the above embodiment (4), the present invention is applied to a system in which the intake valve 15 and the exhaust valve 16 are provided with a variable valve timing mechanism. The present invention is also applicable to a system having a variable valve lift mechanism.

Further, the abnormality diagnosis of the above-mentioned embodiments (3) and (4) is performed at a time other than the steady state (during acceleration or deceleration), similarly to the above-mentioned embodiments (1) and (2). May be. In this way, drivability and emission during abnormality diagnosis can be improved.

[Embodiment (5)] Next, an embodiment (5) of the present invention will be described with reference to FIG. This embodiment (5)
The present invention is applied to a variable valve system in which a variable valve mechanism (variable valve timing mechanism and / or variable valve lift mechanism) is provided in each of the left and right banks of a V-type internal combustion engine. That is, in a system in which variable valve mechanisms are provided in the left and right banks of a V-type internal combustion engine, when an abnormality diagnosis is performed based on a change in the intake air amount or the intake pipe pressure, the variable valve mechanism on the bank that does not perform the abnormality diagnosis operates. In this case, due to the influence, the intake air amount and the intake pipe pressure on the other bank side fluctuate, and accurate abnormality diagnosis cannot be performed.

Therefore, in the present embodiment (4), the abnormality diagnosis program shown in FIG.
An abnormality diagnosis in a system in which variable valve mechanisms are provided in the left and right banks of a V-type internal combustion engine is performed as follows.

First, at step 401, it is determined whether or not there is a request for abnormality diagnosis of the variable valve mechanism of the left bank. If there is a request for abnormality diagnosis of the variable valve mechanism of the left bank, the routine proceeds to step 402, where abnormality diagnosis is performed. The variable valve mechanism of the right bank is not fixed, and the fluctuation of the intake air amount and the intake pipe pressure due to the operation of the variable valve mechanism of the right bank is eliminated. In the next step 403, the abnormality diagnosis of the variable valve mechanism of the left bank is performed. This is executed in the same manner as in the embodiment. Thereafter, the routine proceeds to step 404, where the abnormality diagnosis is terminated, and the variable valve mechanism of the left bank is returned to the normal control. At the next step 405, the variable valve mechanism of the right bank is released and returned to the normal control. , End this program.

On the other hand, if there is no request for abnormality diagnosis of the variable valve mechanism in the left bank in step 401, step 406
To determine whether there is a request for abnormality diagnosis of the variable valve mechanism in the right bank. If there is a request for abnormality diagnosis of the variable valve mechanism of the right bank, the variable valve mechanism of the left bank that does not perform abnormality diagnosis is fixed to eliminate fluctuations in the intake air amount and the intake pipe pressure due to the operation of the variable valve mechanism of the left bank ( Step 407). Thereafter, abnormality diagnosis of the variable valve mechanism in the right bank is executed in the same manner as in the left bank (step 40).
8). Thereafter, the abnormality diagnosis is terminated, and the variable valve mechanism in the right bank is returned to normal control (step 409). The variable valve mechanism in the left bank is unlocked and returned to normal control (step 410). finish.

In this manner, in the variable valve system in which the variable valve mechanisms are provided in the left and right banks of the V-type internal combustion engine, the change in the intake parameter due to the operation of the variable valve mechanism on the bank side where the abnormality is not diagnosed is eliminated. Only the change of the intake parameter due to the operation of the variable valve mechanism of the bank to be diagnosed can be taken out, without being affected by the variable valve mechanism of the bank which does not diagnose abnormally at all,
Abnormality diagnosis can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an entire system according to an embodiment (1) of the present invention;

FIG. 2 is a flowchart showing a flow of processing of an abnormality diagnosis program according to the embodiment (1).

FIG. 3 is a flowchart showing a process flow of an abnormality diagnosis program according to the embodiment (2) of the present invention.

FIG. 4 is a flowchart showing a flow of processing of an abnormality diagnosis program according to the embodiment (3) of the present invention;

FIG. 5 is a flowchart showing a flow of processing of an abnormality diagnosis program according to the embodiment (4) of the present invention.

FIG. 6 is a flowchart showing the flow of processing of an abnormality diagnosis program according to the embodiment (5) of the present invention.

[Explanation of symbols]

11 ... engine (internal combustion engine), 12 ... crankshaft, 13
... intake camshaft, 14 ... exhaust camshaft, 15 ... intake valve,
16: Exhaust valve, 17: Variable valve timing mechanism (variable valve mechanism), 23: Cam shaft sensor, 24: Crank shaft sensor, 29: Air flow meter (intake parameter detection means), 32: Intake pipe pressure sensor (intake parameter detection) Means), 36... ECU (abnormality diagnosis means).

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02D 45/00366 F02D 45/00 366H F term (reference) 3G084 BA23 DA10 DA27 EB11 FA07 FA10 FA11 FA13 FA20 3G092 AA05 AA11 DA01 DA02 DA03 EA03 EA08 EA13 EA15 EA17 EB09 EC01 FA03 FA15 FA44 FB03 FB06 GA12 GA13 HA02Z HA05Z HA07Z HA13X HA13Z HB01Z HE08Z 3G301 HA19 JA03 JA21 JB02 JB09 JB10 KA12 KA16 LA03 LA07 LB02 PE10 PE03 PA08

Claims (5)

[Claims] A variable valve mechanism for variably controlling a valve timing or a valve lift amount of the internal combustion engine; an intake parameter detecting means for detecting an intake air amount or an intake pipe pressure of the internal combustion engine; and an abnormal diagnosis of the variable valve mechanism. Abnormality diagnosis means for performing abnormality diagnosis of the variable valve mechanism based on a change in the detection value of the intake parameter detection means when forcibly operated using the control value for An abnormality diagnosis device for a variable valve system, wherein the abnormality diagnosis is performed when an operation state of the internal combustion engine is other than a steady state. A variable valve timing mechanism for variably controlling a valve timing of the internal combustion engine; a variable valve lift mechanism for variably controlling a valve lift amount of the internal combustion engine; and detecting an intake air amount or an intake pipe pressure of the internal combustion engine. Intake parameter detection means to perform, when one of the variable valve timing mechanism and the variable valve lift mechanism is fixed and the other mechanism is forcibly activated using a control value for abnormality diagnosis. Abnormality diagnosis means for performing abnormality diagnosis of the other mechanism based on a change in a detection value of the intake parameter detection means. 3. An intake side variable valve mechanism for variably controlling at least one of a valve timing and a valve lift amount of an intake valve of an internal combustion engine, and variably controlling at least one of a valve timing and a valve lift amount of an exhaust valve of the internal combustion engine. An exhaust-side variable valve mechanism, an intake-parameter detecting means for detecting an intake air amount or an intake pipe pressure of the internal combustion engine, and one of the intake-side variable valve mechanism and the exhaust-side variable valve mechanism. The abnormality diagnosis of the other variable valve mechanism is performed based on a change in the detection value of the intake parameter detecting means when the other variable valve mechanism is fixed and forcibly activated using the control value for abnormality diagnosis. An abnormality diagnosis device for a variable valve system, comprising: 4. The abnormality diagnosis device according to claim 2, wherein the abnormality diagnosis unit performs the abnormality diagnosis when the operation state of the internal combustion engine is other than a steady state. 5. A variable valve mechanism provided in each of left and right banks of a V-type internal combustion engine, intake parameter detection means for detecting an intake air amount or an intake pipe pressure of the internal combustion engine, and one of the left and right banks The variable valve mechanism of the other bank is fixed, and the variable valve mechanism of the other bank is forcibly operated using the control value for abnormality diagnosis based on a change in the detected value of the intake parameter detecting means when the other variable valve mechanism is used. An abnormality diagnosis means for executing an abnormality diagnosis of a variable valve mechanism of a bank.