JPH0586939A - Controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To keep stable engine driving by detecting malfunction of an opening variable mechanism in an assured manner, in an internal combustion engine having a resonance chamber provided with a variable mechanism in an intake and system, and by switching a calculation of the amount of operational control of the engine (for example, the amount of fuel injection or ignition timing) into a calculation of emergency, when the malfunction is detected. CONSTITUTION:Under a condition where a RC control valve 11 is ON, when an air fuel ratio correction coefficient KLAF is not more than a predetermined value KRCL1 (step S64) and when predetermined time is counted by a RC fail detection timer TFRC, or, under a condition where the RC control valve is OFF, when the KLAF is not more than a predetermined value KRCL2 (step S68), and when a predetermined time is counted by the timer TFRC, it is judged as fail No.1 and fail No.2, respectively, and a Ti map as well as a thetaig map are replaced with maps for fail time (steps S66, S70).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for an internal combustion engine, and more particularly to a control system for an internal combustion engine having a resonance chamber for producing a resonance intake effect in an intake system.

[0002]

2. Description of the Related Art Conventionally, there is known an internal combustion engine having a resonance chamber for producing a resonance intake effect in an intake system. This resonance chamber is intended to reduce the noise caused by the pulsation by originally canceling the pulsation of the pressure in the intake passage by resonance.
It is also known that the intake efficiency of the engine is increased in a predetermined operating range by the resonance intake effect. in this way,
In a predetermined engine rotation range where the resonance chamber can generate the resonance intake effect, an opening / closing valve (a variable opening mechanism) that connects the resonance chamber and the intake passage is opened to increase the engine output (torque) by the resonance intake effect. Is being controlled.

[0003]

However, in the internal combustion engine in the above-mentioned conventional example, when malfunction of the on-off valve, which is a mechanism for changing the opening of the resonance chamber, etc. occurs, the on-off valve is fixed in a closed state by sticking or the like. If it is done,
Despite the fact that the intended intake efficiency of the engine cannot be increased, the fuel supply amount is calculated on the assumption that the resonance chamber is operating. Therefore, a predetermined engine in which the resonance intake effect of the resonance chamber can occur. Since the air-fuel ratio correction value set according to the output of the exhaust gas concentration detector in the rotation range largely deviates from the value during normal operation, the learning value of the air-fuel ratio correction value also deviates from the value during normal operation. There is a problem that proper air-fuel ratio control is not performed. Further, when the open / close valve is fixed in the closed state during the high load operation (WOT) of the engine, the actual ignition timing becomes excessively retarded due to the same reason as described above, and the exhaust system catalyst is overheated. May occur.

Further, even when the on-off valve is fixed in the open state, the air-fuel ratio correction value largely deviates in the opposite direction to the above-mentioned case with respect to the value at the time of normal operation. There is a problem that is not performed, and W
There is a possibility that the actual ignition timing may be excessively advanced at the time of OT.

The present invention has been made in view of the above circumstances, and reliably detects a malfunction of the variable opening mechanism of the resonance chamber,
An object of the present invention is to provide a control device for an internal combustion engine, which is capable of continuing stable operation of the engine when malfunction occurs.

[0006]

In order to achieve the above object, the present invention provides a detection method for detecting an output value of an exhaust gas concentration detector in an internal combustion engine having a resonance chamber provided with an opening variable mechanism in the middle of an intake passage. Means, feedback control means for feedback controlling the output value to a target value, comparing means for comparing the output value of the feedback control means with a predetermined value, and the opening variable when the output value exceeds the predetermined value. An operation determination means for determining a failure of the mechanism, and switching the operation control amount calculation of the engine operation control means from the normal operation calculation to the emergency calculation according to the output of the operation determination means. It is a feature.

[0007]

According to the structure of the present invention, it is determined whether or not the operation time of the output value of the exhaust gas concentration detector exceeds the predetermined value due to the malfunction of the variable opening mechanism of the resonance chamber provided in the intake passage. When it is judged that the operation is defective, the operation control amount calculation is switched to the emergency operation control amount calculation.
A malfunction of the variable aperture mechanism can be reliably detected, and stable operation of the engine can be ensured when the malfunction occurs.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an overall configuration of a control device for an internal combustion engine according to an embodiment of the present invention.

In FIG. 1, 1 is a DOHC series 4 in which each cylinder is provided with an intake valve and an exhaust valve (not shown).
Cylinder internal combustion engine (hereinafter simply referred to as "engine")
Is. In this engine 1, the valve timings of the intake valve and the exhaust valve are a high speed valve timing (high speed V / T) suitable for a high speed rotation range of the engine and a low speed valve timing (low speed V / T) suitable for a low speed rotation range. It can be switched to two stages.

An air cleaner 3 is provided at the upstream end of the intake pipe 2 of the engine 1, and a throttle body 4 is provided in the middle of the intake pipe 2 between the cylinder block of the engine 1 and the air cleaner 3, and the inside thereof. Is provided with a throttle valve 4 '. A throttle valve opening sensor (not shown) is connected to the throttle valve 4 ', which outputs an electric signal corresponding to the opening of the throttle valve 4'to an electronic control unit (hereinafter referred to as "ECU") 5. Supply.

Resonance chamber (resonance chamber, hereinafter referred to as "R
6) is provided in the middle of the intake pipe 2 between the throttle body 4 and the air cleaner 3, and an RC on-off valve 7 is arranged in a communication passage 6'that connects the RC 6 and the intake pipe 2. Has been done.

Diaphragm type actuator 8 for RC6
Is connected to the RC on-off valve 7 via a link mechanism 9. The actuator 8 is in communication with the RC control valve 11 by a pipe 10. By opening / closing the RC control valve 11, negative pressure applied to a diaphragm (not shown) of the actuator 8 is controlled, and the RC opening / closing is performed via the link mechanism 9. The valve 7 is opened and closed.

The RC control valve 11 is a solenoid type switching valve, and its solenoid (not shown) is connected to the output side of the ECU 5. When energized, one end of the pipe 12 is opened, and the pipe 12 is opened. The negative pressure from the vacuum chamber 13 is supplied to the actuator 8 via the
At the same time one end of 2 is closed and the atmosphere is supplied to the actuator 8. Negative pressure in the intake pipe 2 is introduced into the vacuum chamber 13 via the one-way valve 14 and the pipe 15.

The fuel injection valve 16 is connected between the engine 1 and the throttle valve 4 ', is connected to a fuel pump (not shown) of the intake pipe 2, and is electrically connected to the ECU 5.
The valve opening time of fuel injection is controlled by the signal from CU5.

A branch pipe 2'is provided downstream of the throttle valve 4'of the intake pipe 2, and an absolute pressure (PBA) sensor 17 is attached to the tip of the branch pipe 2 '. The P
The BA sensor 17 is electrically connected to the ECU 5,
The absolute pressure PBA in the intake pipe 2 is converted into an electric signal by the PBA sensor 17 and supplied to the ECU 5.

An intake air temperature (TA) sensor 18 is mounted on the wall of the intake pipe 2 downstream of the branch pipe 2 ', and the intake air temperature TA detected by the TA sensor 18 is converted into an electric signal. It is supplied to the ECU 5.

An engine water temperature (TW) sensor 19 composed of a thermistor or the like is attached to the cylinder peripheral wall filled with cooling water of the cylinder block of the engine 1, and the engine cooling water temperature TW detected by the TW sensor 19 is converted into an electric signal. It is converted and supplied to the ECU 5.

A TDC sensor 20 is provided at a predetermined position around the cam shaft or crank shaft (not shown) of the engine 1.
A crank angle (CRK) sensor 21 is attached to each.

The TDC sensor 20 outputs a signal pulse (hereinafter referred to as "TDC signal pulse") at a predetermined crank angle position every 180 ° rotation of the crankshaft of the engine 1.
The TDC signal pulse is supplied to the ECU 5. ECU5
Calculates the ME value that is the reciprocal of the engine speed NE by measuring the generation interval of the TDC signal pulse.

The CRK sensor 21 has a pulse signal (hereinafter referred to as "CRK") at a cycle of the TDC signal pulse, that is, at a constant crank angle cycle shorter than 180 ° (for example, 45 ° cycle).
Signal pulse ") to supply the CRK signal pulse to the ECU 5.

The spark plug 22 of each cylinder of the engine 1 is
It is electrically connected to the ECU 5, and the ECU 5 controls the ignition timing.

A three-way catalyst 24 is arranged in the exhaust pipe 23 of the engine 1 and purifies harmful components such as HC, CO and NOX in the exhaust gas. A proportional output type wide-range oxygen concentration sensor (hereinafter referred to as "LAF sensor") as an exhaust concentration detector is provided on the exhaust pipe 23 upstream of the three-way catalyst 24.
25 is provided, and the LAF sensor 25 outputs an electric signal of a level substantially proportional to the oxygen concentration in the exhaust gas,
Supply to the ECU 5.

On the output side of the ECU 5, a VT control solenoid valve 26 for controlling the switching of the valve timing is provided.
Is connected, and the opening / closing operation of the VT control solenoid valve 26 is performed by the ECU.
Controlled by 5. The VT control solenoid valve 26 switches the hydraulic pressure of a switching mechanism (not shown) for switching the valve timing between high and low, and the valve timing is a high speed V / T corresponding to the high / low of the hydraulic pressure. It is switched to the low speed V / T. The hydraulic pressure of the switching mechanism is detected by a hydraulic pressure (POIL) sensor 27, and the detection signal is supplied to the ECU 5. At the ECU 5, the atmospheric pressure (P
A) The sensor 28 is connected and a signal indicating the atmospheric pressure PA is supplied.

The ECU 5 shapes the input signal waveforms from the various sensors described above, corrects the voltage level to a predetermined level, converts an analog signal value into a digital signal value, and the like, and a central processing unit. Circuit (hereinafter “CP
U ”), a storage means 5c including ROM and RAM for storing various calculation programs executed by the CPU 5b, various maps to be described later, calculation results, etc., the RC control valve 11, the fuel injection valve 16, and the ignition. Output circuit 5 for supplying a drive signal to the plug 22 and the VT control solenoid valve 26
and d.

The CPU 5b determines various engine operating states such as a feedback control operating region and an open loop control operating region according to the oxygen concentration in the exhaust gas based on various engine parameter signals from the above-mentioned sensors. The fuel injection time TOUT of the fuel injection valve 16 is calculated according to the determined engine operating state by the following formula.

[0027]

[Formula 1] TOUT = Ti × KLAF × K₁+ K₂  Here, Ti is the engine speed NE and the engine load.
Depending on the parameter, for example, the absolute pressure PBA in the intake pipe,
This is the basic fuel injection time determined by
The Ti map to be set is stored in the storage means 5c of the ECU 5.
It is remembered.

KLAF is an air-fuel ratio correction coefficient, which is set according to the output of the LAF sensor 25 so that the air-fuel ratio detected by the LAF sensor 25 matches the target air-fuel ratio during air-fuel ratio feedback control, and during open-loop control. Is a predetermined value according to each open-loop control operation region of the engine, or the learning value KR of the correction coefficient with or without the predetermined value.
Set to EF.

K ₁ and K ₂ are other correction coefficients and correction variables calculated according to various engine parameter signals, respectively, and indicate various characteristics of the engine such as fuel consumption characteristics and engine acceleration characteristics according to engine operating conditions. The value is determined so that optimization can be achieved.

Further, the CPU 5b calculates the ignition advance value θig, the ignition coil energization time DUTY and the like based on the various engine parameter signals described above. Ignition advance value θ
ig is calculated by the following formula.

[0031]

[Mathematical formula-see original document] θig = θigMAP + θigK where θigMAP is a parameter representing engine speed NE and engine load, for example, intake pipe absolute pressure PBA.
Is the basic ignition advance angle determined by
A θig map for determining the AP value is stored in the storage means 5c of the ECU 5.

ΘigK is a correction value calculated according to various engine parameter signals.

The CPU 5b further determines a drive signal to the VT control solenoid valve 26 for controlling the switching of the valve timing between the low speed V / T and the high speed V / T according to the engine operating condition such as the engine speed. To do.

Further, the CPU 5b determines a drive signal to the RC control valve 11 in order to control the opening / closing of the RC open / close valve 7 according to the engine operating state.

The CPU 5b calculates the RC control valve 11, the fuel injection valve 16, and the
A drive signal is output to the spark plug 22 and the VT control solenoid valve 26 via the output circuit 5d.

FIG. 2 shows an example of the on-off operating range of the RC control valve 11 of FIG. 1 at the engine speed NE. In this example, the on-operating engine speed range is the engine speed increasing. 2500-3600 rpm
In the meantime, when the engine speed is decreasing, it is between 3500 and 2400 rpm, and a hysteresis is provided when the engine speed is increasing and when the engine speed is decreasing. In the above ON operation range, the RC control valve 11 is turned ON, the RC opening / closing valve 7 is opened, and the resonance intake effect by the RC (resonance chamber) 6 is obtained.

Specifically, when the engine speed NE increases in FIG. 2, the RC control valve 11
Is on when the engine speed NE rises to 2500 rpm and is off when the engine speed NE exceeds 3600 rpm, while it is on when the engine speed NE drops to 3500 rpm as shown by the solid line. And becomes off when the speed drops below 2400 rpm.

FIG. 3 is an engine speed (NE) vs. engine output (PS) curve diagram for explaining the resonance intake effect (hereinafter referred to as RC effect) by the RC on-off valve 7.

In FIG. 3, the solid line A shows the engine output curve at low speed V / T when the RC control valve 11 is off, and the broken line B shows the same curve when the RC control valve 11 is on.

Normally, higher output can be obtained at low engine speed at low speed V / T and at high engine speed range at high speed V / T, but switching from low speed V / T to high speed V / T is achieved. At times, as indicated by solid lines A and C in FIG. 3, the engine output suddenly rises, causing an engine shock.

Therefore, in this embodiment, a region including the V / T switching rotational speed is selected as the engine rotational region in which the RC effect due to the resonance chamber 5 is to be obtained, and the shock at the V / T switching is caused by the increase in the engine output due to the RC effect. I try to relax.

That is, the RC effect region (2500 rpm to 3600 rpm, 350) of the engine speed indicated by the diagonal lines in the figure.
At 0 to 2400 rpm, the output curve when the RC control valve 11 is on (broken line B) exceeds the output curve when it is off (solid line A). Therefore, the RC control valve 11 is turned on only in the engine speed range of FIG.
By increasing the engine output by the C effect, the low speed V / without the RC effect shown by the solid lines A and C in FIG.
It is possible to eliminate the step difference between the output curves of T and the high speed V / T and reduce the engine shock due to the V / T switching. still,
In the RC effect range, the engine output (torque) increases by about 10% due to the resonance intake effect.

4 and 5 show flow charts of a program executed by the CPU 5b of FIG. 1 for obtaining a learning value KREF of the air-fuel ratio correction coefficient KLAF. This program is executed in synchronization with each generation of the TDC signal pulse.

First, in steps S1 to S7, the operating state of the engine is suitable for learning the correction coefficient KLAF, that is, the calculated learning value can accurately reflect variations in engine characteristics and changes with time. It is determined whether or not a stable state or a state where normal control of the air-fuel ratio or the like is possible.
That is, in step S1, it is determined whether or not the engine operating state is fail-safe operation. During fail-safe operation, that is, when the air-fuel ratio is held at a fixed value due to a failure of various sensors or control valves for controlling the engine, an appropriate learning value calculation cannot be performed.
This program ends. If it is not during fail-safe operation, the process proceeds to step S2 and thereafter.

Similarly, in step S2, the atmospheric pressure PA detected by the PA sensor 28 is the predetermined value PAREF.
Whether or not it is larger than the battery voltage V in step S3.
Whether or not B is larger than the predetermined value VBREF, step S4
Then, whether the engine water temperature TW from the TW sensor 15 is larger than a predetermined value TWREF, TA is determined in step S5.
Whether the intake air temperature TA from the sensor 14 is higher than a predetermined value TAREF, whether the engine is in a fuel cut or has passed a predetermined time immediately after the fuel cut in step S6, and in step S7, for example, the CRK sensor 21 is used. Change amount ΔPBA of the intake pipe absolute pressure PBA obtained for each CRK signal pulse sequentially input from
It is determined whether or not it is smaller than PBREF.

When the answer to the above steps S2-S5 and S7 is negative (NO), and when the answer to step S6 is affirmative (YES), this program is immediately terminated.

On the other hand, when the answer to any of the steps S2-S5 and S7 is affirmative (YES), and when the answer to the step S6 is negative (NO), that is, the engine operating state etc. is the learning value KREF calculated. Is suitable for step S8
Then, it is determined whether or not the engine is in the idle operation state. If it is during the idle operation, the procedure proceeds to step S9, and if not, the procedure proceeds to step S10.

In step S9, the learning value KREF0 of the air-fuel ratio correction coefficient KLAF during idle operation is calculated by the following equation, and this program is terminated.

[0049]

[Equation 3] Here, KREF0n- ₁ is the value of KREF0 during the idle operation obtained up to the previous time, a variable that is set to an appropriate value among CREF01 to 256, and KLAFn is the value of KLAF obtained this time.

In step S10, it is determined whether the valve timing is low speed V / T (high speed V / T), and the low speed V / T is determined.
In case of / T, the process proceeds to step S11, and in case of high speed V / T, the process proceeds to step S14.

In step S11, the engine speed NE is equal to the predetermined value NREFL1 (eg 100 rpm) and NR.
It is determined whether or not it is in the range between EFH1 (for example, 2350 rpm), and if it is, step S12
Proceed to step 3. If it is not entered, exit this program.
NREFL1 and NREFH1 are K at low speed V / T
It is set as a lower limit value and an upper limit value of the engine speed NE suitable for the calculation of REF.

In step S12, it is determined whether or not the intake pipe absolute pressure PBA is within a range between a predetermined value PBREFL1 (for example, 260 mmHg) and PBREFH1 (for example, 560 mmHg).
If it does not enter, the program ends. PBREFL1 and PBREFH1 are low speed V / T
It is set as the lower limit value and the upper limit value of the intake pipe absolute pressure PBA suitable for the calculation of KREF at the time.

In step S13, the learning value KREF1 of the air-fuel ratio correction coefficient KLAF during low speed V / T operation is calculated by the following equation, and this program is terminated.

[0054]

[Equation 4] Here, KREF1n- ₁ is the low speed V / obtained by the previous time.
The value of KREF1 during T operation, CREF1 is a variable set to an appropriate value from 1 to 256, and KLAFn is the value of KLAF obtained this time.

In step S14, the engine speed NE is equal to the predetermined value NREFL2 (for example, 2800 rpm) and N.
It is determined whether or not it is in the range between REFH2 (for example, 3800 rpm), and if it is, step S1
Proceed to step 5, and if not entered, end this program. NREFL2 and NREFH2 are set as the lower and upper limit values of the engine speed NE suitable for the calculation of KREF at the time of high speed V / T.

In step S15, it is determined whether or not the intake pipe absolute pressure PBA is within a range between a predetermined value PBREFL2 (eg 260 mmHg) and PBREFH2 (eg 960 mmHg).
Proceed to 16, and if not entered, terminate this program. PBREFL2 and PBREFH2 are high-speed V / T
It is set as the lower limit value and the upper limit value of the intake pipe absolute pressure PBA suitable for the calculation of KREF at the time.

In step S16, the learning value KREF2 of the air-fuel ratio correction coefficient KLAF during the high speed V / T operation is calculated by the following equation, and this program is terminated.

[0058]

[Equation 5] Here, KREF2n- ₁ is the low speed V /
The value of KREF2 during T operation, CREF2 is a variable set to an appropriate value from 1 to 256, and KLAFn is the value of KLAF obtained this time.

In this way, the learning of KLAF obtained by the programs in FIGS. 4 and 5 was obtained this time.
It is the value of F.

In this way, the learning values KREF0, K of KLAF obtained by the programs in FIGS.
REF1 and KREF2 are low speed V /
Used as the initial value of KLAF during air-fuel ratio feedback control during T operation and high speed V / T operation, and during open loop control during idle, low speed V / T operation, and high speed V / T operation. It is used as a set value in place of KLAF.

FIG. 6 is a flow chart of a program for executing the failure detection of the RC on-off valve mechanism 7-11 (hereinafter referred to as "RC fail detection") executed by the CPU 5b of FIG.

First, in step S61, it is determined whether or not the RC failure has been detected. If the RC failure has been detected, another RC failure is detected.
Since fail detection is unnecessary, this program is terminated, and if not detected, the process proceeds to step S62.

In step S62, the intake pipe absolute pressure P
It is determined whether or not BA is equal to or less than a predetermined value PBARC (for example, 660 mmHg). When PBA is equal to or less than PBARC, the engine is in a low load operation state and it is not necessary to increase the engine output, and therefore the RC opening / closing mechanism is in the inoperative state. Since it should be, it is not necessary to execute the subsequent steps S63 and thereafter.
This program ends. When PBA is larger than PBARC, the process proceeds to step S63.

In step S63, the RC control valve 11
Is ON, that is, whether or not the valve opening instruction signal (drive signal) is supplied from the CPU 5b to the RC control valve 11, the process proceeds to step S64 if it is on, and to step S68 if it is off. move on.

In step S64, it is determined whether or not the value of the air-fuel ratio correction coefficient KLAF is less than or equal to a predetermined value KRCL1,
If KLAF is not less than KRCL1, step S71
And if KLAF is less than KRCL1, step S
Proceed to 65. The predetermined value KRCL1 is set to the lower limit value of the range that the value of the air-fuel ratio correction coefficient KLAF can take if the RC on-off valve 7 is opened when the RC on-off valve mechanism is operating normally.

In step S65, it is determined whether or not the RC fail detection timer TFRC has counted a predetermined time (for example, 5 seconds). If the timer TFRC has not counted the predetermined time, the process proceeds to step S71 and the failure occurs. On the other hand, if the determination of occurrence has been suspended, while the timer TFRC has counted the predetermined time, the process proceeds to step S66.

In step S66, it is determined that the RC open / close valve 7 is fixed in the closed state (failure No. 1), and the failsafe process described later is performed, and the learning value KREF of KLAF is set to 1 in step S67. Set to 0 and exit this program.

On the other hand, if it is determined in step S63 that the RC control valve 11 is off, then in step S68 it is determined whether or not the air-fuel ratio correction coefficient KLAF is less than or equal to a predetermined value KRCL2, and if KLAF is not less than KRCL2, step The process proceeds to step S71, and if KLAF is KRCL2 or less, the process proceeds to step S69. The predetermined value KRCL2 is set to the lower limit value of the range that the value of the air-fuel ratio correction coefficient KLAF can take if the RC on-off valve 7 is closed when the RC on-off valve mechanism operates normally.

In step S69, if the RC fail detection timer TFRC has not counted the predetermined time (for example, 5 seconds), the process proceeds to step S71 to suspend the determination of the failure occurrence, while the timer TFRC counts the predetermined time. If so, the process proceeds to step S70.

In step S70, it is determined that the RC open / close valve 7 is in a failure state (failure No. 2) fixed in the open state, and the failsafe process described later is performed, and after executing step S67, this program is executed. To finish.

If the process proceeds to step S71, it is determined that the RC on-off valve mechanism is operating normally without fail,
It proceeds to step S72.

In step S72, the RC fail detection timer TFRC is set and restarted to end this program.

FIG. 7 shows the ignition advance value θ depending on the result of the failure detection of the RC on-off valve mechanism by the program of FIG. 6 described above.
6 is a flowchart showing a program for selecting an ig map and a fuel injection time Ti map.

In the flowchart of FIG. 7, first, in step S81, the fail N is executed by the program of FIG.
o. It is determined whether or not 1 is detected, and if it is detected, the process proceeds to step S82, the fail map 1 applicable when the RC on-off valve 7 is fixed in the closed state is selected, and this program is terminated.

Fail No. If No. 1 is not detected, in step S83, the fail no. It is determined whether or not 2 is detected, and if it is detected, the process proceeds to step S84, the fail map 2 applicable when the RC on-off valve 7 is fixed in the open state is selected, and this program ends. ..

Fail No. If 2 is not detected, the process proceeds to step S85 to select the normal map for normal operation and end the program.

The fail map 1 indicates that the ECU 5 detects when the RC open / close valve 7 is fixed in the closed state.
2 is an ignition advance value θig map and a fuel injection time Ti map read from the storage means 5c of the ignition timing and fuel injection time when the RC on-off valve 7 is fixed in the closed state using the θig map and the Ti map. By calculating, the stable engine operation can be continued.

The fail map 2 is a θig map and a Ti map which are used when a failure in which the RC on-off valve 7 is fixed in the open state is detected.
By calculating the ignition timing and the fuel injection time when the RC on-off valve 7 is fixed in the open state using the g map and the Ti map, stable engine operation can be continued.

The normal map is a θig map and Ti used during normal operation in which the RC on-off valve mechanism is normal.
It is a map.

As described above, according to the present embodiment, the malfunction of the on-off valve mechanism of the resonance chamber 6 is detected by the output of the exhaust gas concentration detector by the processing shown in FIGS. There is an advantage that a simple configuration that only requires processing on a program can be used without using a sensor or the like.

In the above embodiment, the map is switched when a failure is detected. However, the present invention is not limited to this, and the basic injection amount and the basic ignition timing may be corrected by a correction coefficient.

Furthermore, step S6 of the program shown in FIG.
4, in S68, the air-fuel ratio correction coefficient KLAF is compared with the lower limit value that can be taken during normal operation, respectively, but instead of this or together therewith, it may be compared with the upper limit value.

The control whose calculation is to be switched is not limited to the fuel injection amount control and the ignition timing control described above, but may be applied to the intake air amount control, for example.

[0084]

As described above in detail, according to the control device for an internal combustion engine of the present invention, the malfunction of the on-off valve mechanism of the resonance chamber provided in the intake system is detected by the output of the exhaust gas concentration detector, When the malfunction is detected, the calculation is switched to the fuel injection amount or the ignition timing for emergency, so that the stable engine operation can be continued.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a control device for an internal combustion engine of the present invention.

FIG. 2 is a diagram showing the relationship between the operation of the RC control valve of the present invention and the engine speed.

FIG. 3 is a diagram showing a resonance intake effect by the resonance chamber of the present invention.

FIG. 4 is a flowchart showing a learning value calculation program for an air-fuel ratio correction coefficient KLAF according to the present invention.

FIG. 5 is a flowchart showing a learning value calculation program for an air-fuel ratio correction coefficient KLAF according to the present invention.

FIG. 6 is a flowchart showing an RC fail detection program of the present invention.

FIG. 7 is a flowchart showing a program for obtaining a Ti map and a θig map of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 engine 5 ECU (detection means, comparison means, counting means, operation determination means, switching means) 7 RC on-off valve (variable opening mechanism) 11 RC control valve 16 fuel injection valve 22 spark plug 25 LAF sensor (exhaust gas concentration detector)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area F02P 5/15 L 9150-3G

Claims (5)

[Claims] 1. An internal combustion engine having a resonance chamber having an opening variable mechanism in the middle of an intake passage, detecting means for detecting an output value of an exhaust gas concentration detector, and feedback control for feedback controlling the output value to a target value. Means, a comparing means for comparing an output value of the feedback control means with a predetermined value, and an operation judging means for judging a failure of the opening variable mechanism when the output value exceeds the predetermined value. A control device for an internal combustion engine, wherein the calculation of the operation control amount of the operation control means of the engine is switched from the calculation for normal time to the calculation for emergency in accordance with the output of the determination means. 2. The internal combustion engine according to claim 1, wherein the operation determining means determines a failure of the opening variable mechanism when the output value exceeds the predetermined value for a predetermined time or more. Control device. 3. The control device for an internal combustion engine according to claim 1, wherein the operation control amount of the engine operation control means is a fuel injection amount. 4. The control device for an internal combustion engine according to claim 1, wherein the operation control amount of the operation control means of the engine is ignition timing. 5. The control of the internal combustion engine according to claim 1, wherein the calculation of the operation control amount of the operation control means is switched by switching a map according to the load and the rotation speed of the internal combustion engine. apparatus.