JP2001132526A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of minimizing lowering of an exhaust characteristic, by early diagnosing defect of a temperature rise promoting control, in the case where the temperature rise promoting control of the catalyst is carried out by combining an increase in an intake air amount and spark delay control of an ignition timing. SOLUTION: An engine speed NE and ignition timing IGLOG are monitored at a time point where a predetermined delay time TMFIREDLY has passed since the temperature ride promoting control is started (S143, S144). When a state where the engine speed NE is not more than a determination threshold value (MOBJ-DNEFIRE) and/or a state where the ignition timing IGLOG is not less than a determination threshold value DIGJUD is continued on a determination time TMFIRE or more, failure is determined (S147-S151).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine which executes a catalyst temperature increase promotion control for accelerating the temperature increase of an exhaust gas purification catalyst, and more particularly to a failure in which the catalyst temperature increase promotion control is not normally executed. It relates to a device having a function of diagnosing.

[0002]

2. Description of the Related Art An exhaust gas purifying catalyst provided in an exhaust system of an internal combustion engine is inactive at a low temperature and does not exhibit a purifying action. Therefore, immediately after the engine is started, its temperature is raised and activated immediately. It is desirable. Therefore, immediately after the engine is started, the intake air amount of the internal combustion engine is increased from that at the time of normal idling, and the ignition timing is feedback-controlled in the retard direction so that the engine speed (rotation speed) matches the target speed. Is conventionally known (Japanese Patent Application Laid-Open No. H10-299631). According to this technique,
As the intake air amount increases, the fuel supply amount also increases, and the calorific value increases as compared with the normal idling time, thereby facilitating the temperature rise of the catalyst.

[0003]

However, in the above-mentioned conventional apparatus, consideration is given to a failure in which the increase of the intake air amount or the change of the ignition timing in the retard direction is not executed as instructed by the control device. Not. Therefore, when such a failure occurs, the driver may be late to notice and deteriorate the exhaust characteristics immediately after the start.

The present invention has been made with a focus on this point. In the case of executing the catalyst temperature increase promotion control in which the increase of the intake air amount and the ignition timing retard control are combined,
It is an object of the present invention to provide a control device for an internal combustion engine that can diagnose a problem of the temperature increase promotion control at an early stage and can suppress deterioration of exhaust characteristics to a minimum.

[0005]

According to one aspect of the present invention, there is provided an intake air amount control means for controlling an intake air amount of an internal combustion engine provided with a catalyst in an exhaust system;
An internal combustion engine comprising: an ignition timing control means for controlling an ignition timing of the engine; and a catalyst temperature raising means for increasing an intake air amount after starting the engine and delaying the ignition timing in accordance with the engine speed. The control device according to the above, further comprising a failure diagnosis means for diagnosing a failure of the catalyst temperature raising means based on at least one of the engine speed and the ignition timing retard amount during operation of the catalyst temperature raising means. Features.

According to this structure, the failure of the catalyst temperature raising means is diagnosed based on at least one of the engine speed and the ignition timing retard amount during the operation of the catalyst temperature raising means.
The malfunction of the catalyst temperature raising means can be diagnosed at an early stage, and the deterioration of the exhaust characteristics can be suppressed to a minimum.

According to a second aspect of the present invention, in the control apparatus for an internal combustion engine according to the first aspect, the failure diagnosis means includes:
A failure of the catalyst temperature raising means is diagnosed based on a crank angle position at which the engine rotation speed becomes maximum during operation of the catalyst temperature raising means.

According to this configuration, the failure of the catalyst temperature raising means is diagnosed based on the crank angle position at which the engine rotation speed becomes maximum during the operation of the catalyst temperature raising means. It is possible to determine whether or not the ignition timing is accurately retarded from the angular position, and determine a failure from the result. Therefore, it is possible to determine a failure in which the actual ignition timing is different from the generation timing of the ignition timing control signal.

According to a third aspect of the present invention, in the control apparatus for an internal combustion engine according to the first aspect, the failure diagnosis means includes:
A failure of the catalyst temperature raising means is diagnosed based on a variation amount of the ignition timing during operation of the catalyst temperature raising means. According to this configuration, the failure of the catalyst temperature raising means is diagnosed based on the variation of the ignition timing during the operation of the catalyst temperature raising means, so that the ignition timing is shifted in the advance direction or the retard direction as a whole. In such a case, an accurate determination can be made.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an internal combustion engine (hereinafter referred to as an “engine”) and a control device thereof according to an embodiment of the present invention. For example, a throttle valve 3 is provided in the intake pipe 2 of a four-cylinder engine 1. Is arranged. The throttle valve 3 has a throttle valve opening (θTH) sensor 4
And outputs an electric signal corresponding to the degree of opening of the throttle valve 3 and supplies it to an electronic control unit (hereinafter referred to as “ECU”) 5.

An auxiliary air passage 17 that bypasses the throttle valve 3 is connected to the intake pipe 2.
7, an auxiliary air control valve 18 for controlling the amount of auxiliary air.
Is provided. The auxiliary air control valve 18 is connected to the ECU 5, and the ECU 5 controls the valve opening amount.

A fuel injection valve 6 is provided for each cylinder so as to inject fuel into the intake pipe 2. Each injection valve is connected to a fuel pump (not shown) and electrically connected to the ECU 5. The fuel injection valve 6 is operated by a signal from the ECU 5.
Is controlled. On the other hand, an intake pipe absolute pressure (PBA) sensor 7 is provided immediately downstream of the throttle valve 3, and the absolute pressure signal converted into an electric signal by the absolute pressure sensor 7 is supplied to the ECU 5. Further, an intake air temperature (TA) sensor 8 is attached downstream of the ECU 5 and detects the intake air temperature TA to output a corresponding electric signal to the ECU 5.
To supply.

The engine water temperature (TW) sensor 9 mounted on the main body of the engine 1 is composed of a thermistor or the like, detects the engine water temperature (cooling water temperature) TW, outputs a corresponding temperature signal, and supplies it to the ECU 5. The ECU 5 includes the engine 1
A crank angle position sensor 10 for detecting the rotation angle of a crankshaft (not shown) is connected, and a signal corresponding to the rotation angle of the crankshaft is supplied to the ECU 5. The crank angle position sensor 10 outputs a signal pulse (hereinafter referred to as a “CYL signal pulse”) at a predetermined crank angle position of a specific cylinder of the engine 1, and a top dead center (TDC) at the start of an intake stroke of each cylinder. TDC that outputs a TDC signal pulse at a crank angle position before a predetermined crank angle (for every 180 degrees of crank angle in a four-cylinder engine)
A CRK sensor that generates one pulse (hereinafter referred to as a “CRK signal pulse”) at a constant crank angle cycle (for example, a 30-degree cycle) shorter than the TDC signal pulse,
The YL signal pulse, the TDC signal pulse, and the CRK signal pulse are supplied to the ECU 5. These signal pulses are used for various timing controls such as fuel injection timing, ignition timing, etc., and detection of an engine speed (engine speed) NE.

An ignition plug 11 provided for each cylinder of the engine 1 is connected to the ECU 5,
The first drive signal, that is, the ignition signal is supplied from the ECU 5. The three-way catalyst 16 is disposed in the exhaust pipe 12 of the engine 1 and purifies components such as HC, CO, and NOx in the exhaust gas. On the upstream side of the three-way catalyst 16 of the exhaust pipe 12,
A proportional air-fuel ratio sensor 14 (hereinafter, referred to as a “LAF sensor 14”) is mounted, and the LAF sensor 14 outputs a detection signal that is substantially proportional to the oxygen concentration (air-fuel ratio) in the exhaust gas and supplies it to the ECU 5.

The ECU 5 includes a vehicle speed sensor 21 for detecting a traveling speed (vehicle speed) VP of a vehicle driven by the engine 1, an atmospheric pressure sensor 22 for detecting an atmospheric pressure PA, and a shift position of an automatic transmission of the vehicle. The shift position sensors 23 are connected to each other, and detection signals from these sensors are supplied to the ECU 5.

The ECU 5 has a function of shaping input signal waveforms from various sensors, correcting a voltage level to a predetermined level, converting an analog signal value to a digital signal value, and the like, and a central processing circuit ( The CPU 5b includes a storage unit 5c for storing various calculation programs executed by the CPU 5b, calculation results, and the like, an output circuit 5d for supplying a drive signal to the fuel injection valve 6, the ignition plug 11, and the like. Is done.

The CPU 5b determines various engine operating states based on the various engine parameter signals described above, and according to the determined engine operating states,
Based on the following equation (1), a fuel injection time TOUT by the fuel injection valve 6 that operates to open in synchronization with the TDC signal pulse is calculated. TOUT = TI × KCMD × KLAF × K1 + K2 (1) Here, TI is a basic fuel injection time of the fuel injection valve 6, and a TI map set according to the engine speed NE and the intake pipe absolute pressure PBA is searched. Is determined. TI
The map indicates that the engine 1 is in an operating state corresponding to the engine speed NE and the intake pipe absolute pressure PBA on the map.
Is set such that the air-fuel ratio of the air-fuel mixture supplied to the air-fuel mixture becomes substantially the stoichiometric air-fuel ratio.

KCMD is a target air-fuel ratio coefficient. The engine speed NE, the intake pipe absolute pressure PBA, and the engine coolant temperature T
It is set according to the engine operating parameters such as W. The target air-fuel ratio coefficient KCMD is proportional to the reciprocal of the air-fuel ratio A / F, that is, the fuel-air ratio F / A, and takes a value of 1.0 at the stoichiometric air-fuel ratio. KLAF is an air-fuel ratio correction coefficient calculated by PID control such that the detected equivalent ratio KACT calculated from the detection value of the LAF sensor 14 matches the target equivalent ratio KCMD.

The CPU 5b further calculates the ignition timing IGLOG according to the following equation (2). IGLOG = IGMAP + IGCR + IGGFPI (2) Here, IGMAP is a basic value of the ignition timing obtained by searching an IG map set according to the engine speed NE and the absolute pressure PBA in the intake pipe, that is, the advance angle from the top dead center. It is the ignition timing indicated by the quantity. IGFPI is a retardation correction term that is set to a negative value so that the engine speed NE matches the target speed NEFIR during the rapid warm-up retard control during the warm-up operation of the engine 1 as described later. Yes, IGCR is a correction term other than the retardation correction term IGFPI. (IGMAP + IGCR) corresponds to the ignition timing at the time of the normal control in which the rapid warm-up retard control is not performed. In the following description, the operation mode in which the rapid warm-up retard control is executed is referred to as “FIRE mode”.

The CPU 5b supplies a signal for driving the fuel injection valve 6 to the fuel injection valve 6 based on the fuel injection time TOUT obtained as described above, and sets the ignition timing IG
A signal for driving the spark plug 11 based on the LOG is supplied to the spark plug 11. Further, the CPU 5b calculates a valve opening control amount ICMD for controlling the valve opening amount of the auxiliary air control valve 18 according to the engine operating state, and calculates the valve opening control amount IC
A drive signal corresponding to the MD is supplied to the auxiliary air control valve 18. In the FIRE mode (and in a transient state immediately after the end of the FIRE mode), the CPU 5b calculates the valve opening control amount ICMD by the following equation (3). Auxiliary air control valve 18
Is configured to be proportional to the valve opening control amount ICMD. ICMD = (IFIR + ILOAD) × KIPA + IPA (3)

Here, IFIR is a FIRE mode control term used in the FIRE mode (and in a transient state immediately after the end of the FIRE mode), and ILOAD is an electric load applied to the engine 1, a compressor load of the air conditioner, and a power steering load. A load correction term set according to whether the automatic transmission is in-gear or not, such as KIP
A and IPA are an atmospheric pressure correction coefficient and an atmospheric pressure correction term set according to the atmospheric pressure PA.

FIGS. 2 and 3 show the FIRE mode and the FIR mode.
Immediately after E mode ends, FIRE mode control term IFI
9 is a flowchart of a main routine for calculating R. This routine is executed by the CPU 5b in synchronization with the generation of the TDC signal pulse.

In step S11, a FIRE mode determination process shown in FIG. 5 is executed. In the FIRE mode determination process, the FIRE mode flag F indicated by “1” indicates that the transition to the FIRE mode or the continuation of the FIRE mode is permitted.
Processing such as setting of FIREON is performed. Step S
In step S12, it is determined whether or not the FIRE mode flag FFIREON is "1". If FFIREON = 0 and the transition to the FIRE mode or the continuation of the FIRE mode is not permitted, step S26 (FIG. 3)
When FFIREON = 1 and the transition to the FIRE mode or the continuation of the FIRE mode is permitted, the transient control flag FFIRQUIT indicating "1" indicating that the transient control is being performed immediately after the end of the FIRE mode is set. It is set to "0" (step S13), and the IFI shown in FIG.
An R calculation subroutine is executed (step S14). Then, the FIRE mode control term IFIR calculated in step S14 is compared with the engine water temperature control term ITW (the engine water temperature control term ITW
Is a control term used for controlling the auxiliary air control valve 18 during an idle operation other than the FIRE mode.)
From the predetermined value DIFIRL for setting the lower limit (for example, air amount 1
It is determined whether or not the lower limit (ITW-DIFIRL) is equal to or less than the lower limit (ITW-DIFIRL) obtained by subtracting the value of (00 liter / min) (step S15). If there is, the FIRE mode control term IFIR is set to its lower limit (ITW-DIFIRL) (step S1).
6), end this processing.

In step S26 of FIG. 3, it is determined whether or not the engine coolant temperature control term ITW is smaller than an upper limit initial value IFIRINIH (for example, a value corresponding to an intake air amount of 600 liters / min). If ITW <IFIRINIH, it is determined. , The initial value IFIR used in step S64 of FIG.
While INI is set to the engine coolant temperature TW control term ITW (step S27), if ITW ≧ IFIRINIH, the initial value IFIRINI is set to the upper limit initial value IFIRI.
NIH is set (step S28).

In the following step S29, the subtraction correction value IFIRDEC updated in step S63 of FIG. 7 and used in step S65 is set to "0", and then it is determined whether or not the transient control flag FFIRQUIT is "1". (Step S31) If FFIRQUIT = 1 and the transient control is being performed, the process immediately proceeds to step S35. Also FFIRQU
When IT = 0 and the transient control is not in progress, the previous FIR
It is determined whether or not the E mode flag FFIREON was "1" (step S32), and the previous FFIREON = 1.
If it is immediately after the end of the FIRE mode, the transient control flag FFIRQUIT is set to "1" (step S33), and the process proceeds to step S35.

In step S32, the last time FFIREON = 0
Is incremented in step S50 of FIG. 5, and the FI counts the number of continuations of the FIRE mode.
The RE mode on counter CFIRON is set to "0" (step S34), and the transient control flag FFIR is set.
QUIT is set to “0” (step S39), and this processing ends.

In step S35, the ignition timing IGLOG
Is determined to be larger than a threshold value IGFPIQU (for example, −3 degrees) for determining the end of the transient control, and if IGFPI> IGGFPIQH, the absolute value of the retardation correction term IGFPI is small (retardation angle). If the amount is small, the process proceeds to step S39 to end the transient control.

In step S35, IGFPI ≦ IGFPI
If QH, the DFIRQU table shown in FIG. 4 is searched according to the engine coolant temperature TW, and the transient control subtraction value DF is searched.
Calculate IRCU (step S36). DFIRQUA
The table is set such that the transient control subtraction value DFIRQU decreases as the engine coolant temperature TW increases.
DFIRQUmax, DFIRQUmin and TWDF0, TWDF1 in the figure are set to, for example, a value corresponding to an intake air amount of 5 liter / min, a value corresponding to 2 liter / min, and 28 ° C. and 62 ° C., respectively.

In the following step S37, the FIRE mode control term IFIR is decremented by the transient control subtraction value DFIRQU, and then the FIRE mode control term IFIR is decremented from the engine coolant temperature control term ITW by the predetermined value DIF for lower limit value setting.
It is determined whether or not it is equal to or less than a lower limit obtained by subtracting IRL (step S38), and IFIR> ITW-DIFIRL
Immediately, and IFIR ≦ ITW-DIFI
If it is RL, the above step S39 is executed, and this processing ends.

As described above, in the processing shown in FIG.
The setting of the initial value IFIRINI of the E mode control term IFIR (steps S26 to S28), the transient control immediately after the end of the FIRE mode (steps S31 to S38), and the initialization of the parameters used in the control described later (step S29,
S34) is executed. By the transient control, the intake air amount increased in the FIRE mode is gradually returned to the value of the normal control.

FIG. 5 is a flowchart of the FIRE mode determination process executed in step S11 of FIG. 3. In step S41, it is determined whether or not the designated failure has already been detected. It is determined whether or not the engine 1 is starting (cranking) (step S42). If the answer to step S41 or S42 is affirmative (YES), the flow chart shown in FIG.
A TFIREND table shown in (a) is searched, and a FIRE mode end time TFIREND referred to in step S46 described later is calculated (step S43). TFI
The REND table is set so that the FIRE mode end time TFIREND becomes shorter as the engine coolant temperature TW becomes higher, and TFIRENDmax and T
FIRENDmin is set to, for example, 50 seconds and 2 seconds, respectively, and TW0 and TW1 are each set to, for example, -10.
C and 75C are set.

In the following step S44, an end flag FFIRE indicating that the FIRE mode should be ended is indicated by "1".
ND is set to “0” and then the FIRE mode flag F
FIREON is set to "0" (step S56), and this process ends. If the answers of steps S41 and S42 are both negative (NO), the end flag FFIREND
Is determined to be "1" (step S45), and F
If FIREND = 1, the above step S
On the other hand, when FFIREND = 0, the value of the up-count timer TM20TCR for measuring the elapsed time from the start completion time (cranking end time) is determined by the FIRE mode end time TFI calculated in step S43.
REND is determined (step S4)
6). When TM20TCR> TFIREND, the end flag F is set to end the FIRE mode.
FIREND is set to "1" (step S48),
Proceed to step S56.

At step S46, TM20TCR≤TFI
If it is REND, the end flag FFIREND is set to "0" (step S47), and the engine speed N
E is a predetermined lower limit rotational speed NEFIRL (for example, 700 rpm
m) or not (step S49). NE <
If NEFIRL, the process proceeds to step S56, and if NE ≧ NEFIRL, the FIRE mode on counter CFIRON is incremented by “1” (step S50), and according to the value of the counter CFIRON, as shown in FIG. The KMFIR table shown is searched to calculate a duration correction coefficient KMFIR used in the processing of FIG. 7 (step S51). The KMFIR table is set so that the correction coefficient KMFIR increases as the value of the counter CFIRON increases, and the correction coefficient KMFIR decreases as the value of the counter CFIRON further increases. KMFIRmax, KMFIRmi in the figure.
n and n1 are set to, for example, 2.625, 1.0, and 2000, respectively.

In the following step S52, the KTAFIR table shown in FIG. 6C is searched according to the intake air temperature TA.
The intake temperature correction coefficient KTAFIR used in the processing of FIG. 7 is calculated. The KTAFIR table is set so that the correction coefficient KTAFIR increases as the intake air temperature TA increases, and KTAFIRmax, KTAFIRmin, and TA0 and TA1 in the figure are, for example, 2.0, 1.0 and −10 ° C., 80, respectively. Set to ° C.

In the following step S53, it is determined whether or not the vehicle speed VP is equal to or higher than a predetermined vehicle speed VFIRH (for example, 5 km / h). When VP <VFIRH, it is indicated by "1" that the engine 1 is in an idle state. Idle flag FI
It is determined whether or not DLE is "1" (step S5).
4). When VP ≧ VFIRH and the vehicle is running, or when FIDLE = 0 and the vehicle is not in an idle state, the process proceeds to step S56, and the FIRE mode flag FFIREON is set to “0”. on the other hand,
If VP <VFIRH and the engine 1 is in the idle state, the FIRE mode flag FFIREON is set to "1" (step S55), and this processing ends.

FIG. 7 is a flowchart showing the operation of I in step S14 of FIG.
It is a flowchart of an FIR calculation subroutine. In a step S61, it is determined whether or not a misfire has been detected. Misfire occurs every 30 degrees of crank angle.
It is detected by a known method based on a change in the generation interval of the K signal pulse. When the occurrence of misfire is not detected, the ignition timing IGLOG is set to the lower limit value IGLGG (for example, -20d
eg), a sticking determination value IGIRDEC (for example, 1
(Step S6).
2). And no misfire has occurred and IGLOG ≧
Immediately when IGLGG + IGIRDEC, or when misfire is detected or when IGLOG <IGLGG + IG
FIRDEC and ignition timing IGLOG is lower limit value IG
When it is stuck near LGG, the subtraction correction value IFIRDEC (<0) used in step S65 described later.
Is decremented by a predetermined amount DIFIRDEC (step S63), and the process proceeds to step S64.

In step S64, the basic value IFIRB of the FIRE mode control term IFIR is calculated by the following equation (4).
Calculate S. IFIRBS = IFIRINI × (1+ (KMFIR-1) × KTAFIR) (4) Here, KMFIR and KTAFIR are the duration correction coefficients calculated in steps S51 and S52 of FIG. 5, and IFIRINI is the step of FIG. S27 or S
This is the initial value set at 28. Duration correction coefficient KM
FIR is the elapsed time (increase in count value CFIRON)
6 (b), the intake air amount basically increases gradually from the start of the FIRE mode, then gradually decreases, and then changes to a substantially constant value. It is controlled to be maintained (see FIG. 15A).

In the following step S65, step S64
The FIRE mode control term IFIR is calculated by adding the subtraction correction value IFIRDEC updated in step S63 to the basic value IFIRBS calculated in step S63. By adding the subtraction correction value IFIRDEC (<0), when misfire is detected or when the lower limit of the ignition timing IGLOG is stuck, the intake air amount is corrected in a decreasing direction, and the unburned fuel emission increases. Alternatively, it is possible to avoid a situation in which the retard correction of the ignition timing IGLOG becomes impossible (the engine speed NE cannot be made equal to the target speed NEFIR).

FIG. 8 is a flowchart of the ignition timing control process. This process is executed by the CPU 5b in synchronization with the generation of the TDC signal pulse. In step S71, the basic ignition timing IGMAP is calculated according to the engine speed NE and the intake pipe absolute pressure PBA, and then the retard correction term IGF
A correction term IGCR other than PI is calculated (step S7)
2). In step S73, a feedback (FB) control execution condition determination process shown in FIG. 9 is executed. In this process, the condition for performing feedback control for controlling the ignition timing is determined so that the detected engine speed NE matches the FIRE mode target speed NEFIR, and the feedback control flag FFIRENEF is set when the condition is satisfied.
Set B to “1”.

In step S74, it is determined whether or not the feedback control flag FFIRENEFB is "1". When FFIRENEFB = 0, the retard correction term IGFPI is set to "0" (step S7).
5), when FFIRENEFB = 1 and the execution condition is satisfied, the retard correction term I according to the engine speed NE.
Feedback control for setting the GFPI is executed (step S76). In step S77, the ignition timing IGLOG is calculated by the above equation (2), and this processing ends.

FIG. 9 is a flowchart of the FB control execution condition determining process executed in step S73 of FIG. In step S91, the FIRE mode flag FF
It is determined whether or not IREON is “1”, and FFIRE is determined.
If ON = 0 and the mode is not the FIRE mode, it is determined whether or not the transient control flag FFIRQUIT is “1” (step S103). And FFIRQUIT
= 0 and during the transient control, both the feedback control flag FFIRENEFB and the target rotational speed flag FNOENEFIR (see FIG. 12, step S131) indicating "1" indicating that the target rotational speed in the feedback control is not increased are set to "1". 0 ”(step S
105), and end this process.

In step S103, FFIRQUIT = 1
And during the transient control, the throttle valve opening θ
TH is a predetermined opening θTHFIR (for example, 0.88 deg)
It is determined whether or not this is the case (step S104). θTH <
If θTHFIR and the throttle valve is almost fully closed, this process is immediately terminated and θTH ≧ θTHFI
If R, the process proceeds to step S105. If this processing is to be terminated immediately from step S104, the FI
FFI even if RE mode flag FFIREON = 0
RENEFB = 1 is maintained, and the feedback control is continued.

If FFIREON = 1 in step S91, it is determined whether or not the transient control flag FFIRQUIT is "1" (step S92).
When IT = 1, the feedback control flag FF
IRENEFB is set to "0" (step S9).
4) Go to step S95. Also, FFIRQUIT =
When it is 0, the feedback control flag FFIRE
It is determined whether or not NEFB is already set to "1" (step S93). If FFIRENEFB = 1, this process is immediately terminated. If FFIRENEFB = 0, the process proceeds to step S95.

In step S95, it is determined whether or not the value of an up-count timer TM01ACR for measuring the elapsed time after the start is completed (cranking is completed) is equal to or less than a predetermined time T1STFIR (for example, 1 msec).
When T1STFIR is just after starting, the feedback control start determination addition value NEFPIST, the target rotation speed correction addition value DNEFIR, and the feedback control start determination count value CFNEFBST are each set to a first value NEFPI1 (for example, 200 rpm). , DNE
F1 (eg, 1 rpm) and CFNEFB1 (eg, 2 rpm)
00) (step S96), while TM01A
When CR> T1STFIR, the feedback control start determination addition value NEFPIST, the target rotation speed correction addition value DNEFIR, and the feedback control start determination count value CFNEFBST are each converted into a second value N
EFPI2 (for example, 200 rpm), DNEF2 (for example, 12 rpm) and CFNEFB2 (for example, 2) are set (step S97).

In the following step S98, it is determined whether or not the engine speed NE is equal to or greater than a value obtained by adding the feedback control start determination additional value NEFPIST to the target speed NOBJ in the normal control. If NE <NOBJ + NEFPIST, then FIRE mode on counter CFIRON
Is the count value CFN for determining the start of feedback control.
It is determined whether it is equal to or more than EFBST (step S99).
As a result, the answers of steps S98 and S99 are both negative (NO), the engine speed NE is low and the FIR
If the E-mode duration is short, this processing is immediately terminated, assuming that the feedback control is not executed.

In step S98, NE ≧ NOBJ +
If NEFPIST, the target rotational speed flag FNO
ENEFIR is set to "1" (step S101),
If CFIRON ≧ CFNEFBST in step S99, the target rotation speed flag FNOENEFIR is set to “0” (step S100), and step S1 is performed.
Go to 02. Thus, when the engine speed NE at the start of the feedback control is high (NE ≧ NOBJ + NE)
FPIST) is the FIRE mode target rotation speed NEFIR
Is set to "0" (step S1 in FIGS. 12 and 10).
17, S118)). In step S102, the feedback control flag FFIRENEFB is set to "1" and the FIRE mode on-counter CFIR
The value of ON is stored as a storage value CFRPIST.

FIG. 10 is a flowchart of the feedback control process executed in step S76 of FIG.
In step S111, the target rotation speed addition value ENEFIR
Is performed (FIG. 12), and the added value ENEF is set.
Make IR settings. In step S112, it is determined whether or not the shift position SFT of the automatic transmission has changed from neutral N or parking P to drive D or reverse R (in-gear state) or vice versa. A predetermined time TINGGFIR (for example, 3 seconds) is set in the down count timer tmINGGFIR to be started (step S113),
Both the I term IIGFIR of the feedback control and the retard correction term IGFPI are held as the previous value (step S11).
4), end this processing.

If there is no change in the shift position in step S112, the timer tm started in step S113
It is determined whether the value of INGFIR is “0” (step S
115), while tmINGFIR> 0, the process proceeds to step S114. When tmINGFIR = 0,
It is determined whether the shift position SFT is the drive D or the reverse R (in-gear state) (step S116). If the shift position SFT is not in the in-gear state, the FIRE mode target rotational speed NEFIR is calculated by the following equation (5) (step S11).
7), and proceed to step S121. NEFIR = NOBJ + ENEFIR (5) Here, NOBJ is a target rotational speed in a normal idle state (other than the FIRE mode), and ENENFIR
Is a target rotation speed addition value calculated in step S111.

When the shift position SFT is the drive D or the reverse R in step S116, that is, when the vehicle is in the in-gear state, the FIRE mode target rotational speed NEFIR is calculated by the following equation (6) (step S118). NEFIR = NOBJ + ENEFIR−DNEFIDR (6) Here, DNEFIRDR is an in-gear correction value set to, for example, 300 rpm.

In the following step S119, it is determined whether or not the FIRE mode target rotational speed NEFIR is equal to or lower than a lower limit value NEIGFIRL (for example, 730 rpm).
As soon as NEIGFIRL and NEFIIR
If ≤ NEIGFIRL, the target rotational speed NEFIR
Is set to its lower limit value NEIGFIRL (step S
120), and proceed to step S121.

In step S121, the ignition timing IGLO
The KIIGFIR table shown in FIG. 11 is searched according to G, and the integral term gain KIIGFIR is calculated. KIIG
The FIR table is set so that the integral term gain KIIGFIR increases as the ignition timing IGLOG increases (advances). In FIG. 11, KIIGFIRm
ax, KIIGFIRmin and IGLOG1, IGL
OG2 is set to, for example, 0.063, 0.016, -10 degrees, and 12 degrees, respectively.

In the following step S122, the addition value IIGFTMP is calculated by applying the engine speed NE, the FIRE mode target speed NEFIR, and the integral term gain KIIGFIR to the following equation (7). IIGFTMP = KIIGFIR × (NEFIR-NE) (7) In the following step S123, the previous value of the integral term IIGFI
The integral term (current value) IIGFIR is calculated by adding the addition value IIGFTMP to R (n-1), and then the proportional term PIGFIR is calculated by the following equation (8) (step S124). PIGFIR = KPIGFIR × (NEFIR−NE) (8)

Next, the integral term IIGFIR and the proportional term PI
The GFIR is added to calculate the retardation correction term IGFPI (step S125), and the process ends. As described above, the retardation correction term I so that the engine speed NE matches the FIRE mode target speed NEFIR by the processing of FIG.
Feedback control for calculating GFIR is executed.

FIG. 12 is a flowchart of the ENEFIR setting process executed in step S111 of FIG. In step S131, the target rotation speed flag FNOE
It is determined whether or not NEFIR is “1”, and FNOEN
If EFIR = 1 and the target rotation speed is not to be increased, the target rotation speed addition value ENEFIR is set to “0” (step S134), and the process ends.

If FNOENEFIR = 0, an addition value ENEFIR is calculated by the following equation (9) (step S132). ENEFIR = NEFPIST−DNEFIR × (CFIRON−CFIRPIST) (9) Here, NEFPIST and DNEFIR are the additional value for determining the feedback control start and the additional value for correcting the target rotational speed set in step S96 or S97 in FIG. CFIRON is the value of the FIRE mode on counter,
CFIRPIST is the stored value stored in step S102 of FIG. That is, (CFIRON-CFIR
PIST) is a count value corresponding to the elapsed time from the start of the feedback control. Therefore, the FIRE mode target rotational speed NEFIR is equal to (NOBJ + NEFPIST) at the beginning of the feedback control according to the formula (9) and the formula (5) or (6). Rotation speed NOBJ
(See FIG. 15C).

In the following step S133, the added value ENE
It is determined whether or not the FIR is equal to or less than 0, and if ENEFIR ≦ 0, the process proceeds to step S134, where ENEFIR>
If it is 0, the present process is immediately terminated.

FIGS. 15 (a), 15 (b) and 15 (c) are time charts for explaining the above-described intake air amount control and ignition timing control.
8 shows changes in the valve opening control amount ICMD, the ignition timing IGLOG, and the engine speed NE.

In the illustrated example, starting (cranking) is started at time t0, and when the self-sustaining operation is started at time t1, the mode immediately shifts to the FIRE mode. As the engine speed NE increases, the execution condition of the feedback control of the ignition timing is satisfied at time t2, and the feedback control is started. The FIRE mode target rotational speed NEFIR is initially equal to (NEOBJ + NEFPIST) as described above, and is thereafter gradually reduced to the target rotational speed NOBJ of the normal control.

The valve opening control amount ICMD is controlled so as to gradually increase and then decrease when the mode shifts to the FIRE mode. Immediately after ending the FIRE mode at time t4,
It is controlled so as to be gradually reduced by the transient control. The retardation correction term IGFPI changes as shown by a broken line in FIG. 4B, and the ignition timing IGLOG is set to the normal control value (IGMA
(P + IGCR). When the shift position SFT shifts from the neutral N to the in-gear state at the time t3, the engine load increases, so that the retard correction term IGFPI increases (the retard amount decreases) and the engine output torque increases while the engine rotation increases. The number NE is controlled to be maintained at the target rotational speed NEFIR (= NOBJ). After time t4, control is performed so as to gradually shift to the normal control value.

During the period from time t2 to t4, the engine speed NE is set to the target engine speed NEFIR by feedback control.
Is controlled to match. The illustrated example shows a case where the vehicle starts immediately after time t4, and the vehicle speed VP
Gradually increase.

FIG. 13 is a flowchart of a failure determination process for determining a failure in which the operation in the FIRE mode is not performed normally.
The processing is executed by the CPU 5b in synchronization with the generation of the signal pulse.
In step S141, the determination permission flag FGOFIRE indicating that the condition for executing the failure determination is satisfied is indicated by "1".
Is determined to be “1” or not, and if FGOFIRE = 0 and the execution condition is not satisfied, the delay down count timer tmFILEDLY is set to a predetermined delay time TMFI.
REDLY (for example, 2 seconds) is set and started (step S143), and a determination time TMFIRE (for example, 15) is set in a down-count timer tmFIRE for failure determination.
Second) and start (step S145),
The ignition timing IGLOG is stored as the storage value IGLOGST (step S146), and the process ends. here,
The predetermined delay time TMFIREDLY is set so that step S147 and the subsequent steps are executed after the ignition timing IGLOG shifts to the retard side (negative value) by the feedback control of the ignition timing (see FIG. 15B). .

If FGOFIRE = 1 in step S141, it is determined whether or not the FIRE mode flag FFIREON is "1" (step S142).
If FIREON = 0 and the mode is not the FIRE mode, the process proceeds to step S143. FFIREON = 1
If it is determined that the value of the timer tmFIREDLY started at step S143 is "0" (step S144), the process proceeds to step S145 while tmFIREDLY> 0.

When tmFIREDLY = 0, it is determined whether the value of the failure determination timer tmFIRE is "0" (step S147). At first, tmFIRE>
0, the engine speed NE becomes the target engine speed NOB.
J, a predetermined deviation amount DNEFIRE (for example, 200 rpm
It is determined whether the value is higher than the value obtained by subtracting p) (step S).
148), when NE> NOBJ−DNEFIRE, the ignition timing IGLOG is further reduced to the determination threshold DIGJUD.
It is determined whether or not it is smaller (on the retard side) (step S)
150). If the answers of steps S148 and S149 are both affirmative (YES) and the engine speed NE and the ignition timing IGLOG are within the normal ranges, the failure determination timer tmFIRE is held so as not to count down ( Step S150).

Therefore, if the FIRE mode ends in this state, the process proceeds from step S142 to step S143 without determining that a failure has occurred. On the other hand, if the answer to step S148 or S149 is negative (NO), the failure determination timer tmFIR
When the countdown of E advances and tmFIRE = 0, it is determined that a failure has occurred, and steps S147 to S151 are performed.
And a failure flag FFI indicating "1" indicating that a failure in which the operation of the FIRE mode is not performed normally occurs.
RENG is set to "1" (step S151), and the process ends.

FIG. 14 is a flowchart of a process for judging the execution condition of the fault judgment. This process is executed at predetermined time intervals or in synchronism with the generation of the TDC signal pulse.
5b. In step S161, it is determined whether or not the engine is in the start mode, that is, whether or not cranking is being performed.
It is stored as an IT (step S162), and this processing ends.

After the start is completed, the initial intake air temperature TAIN
Both the IT and the initial water temperature TWINIT are predetermined upper and lower limit values TAFIREH and TAFIREL (for example, 4.5 ° C.,
It is determined whether they are within the range of −6.7 ° C.) and TWFIREH, TWFIREL (for example, 4.5 ° C., −6.7 ° C.) (step S163). And TAFIREL
<TAINIT <TAFIREH and TWFIREL <
When TWINIT <TWFIREH, the deviation (==) between the initial water temperature TWINIT and the initial intake air temperature TAINIT.
TWINIT-TAINIT) is the predetermined deviation DFIRET
(For example, 7 deg) is determined (step S164), and TWINIT-TAINIT <DFIR
When ET, the absolute pressure PBA in the intake pipe is equal to the predetermined pressure PB
It is determined whether it is equal to or more than FIRE (for example, 34.7 kPa) (step S165). As a result, step S163
When all of the answers from S165 to S165 are affirmative (YES), it is determined that the execution condition is satisfied, and the determination permission flag FGOFIRE is set to "1" (step S166), while any of the answers from steps S163 to S165 is negative. (NO), that is, when the initial intake air temperature TAINIT or the initial water temperature TWINIT is not within the range of the predetermined upper and lower limit values, when the deviation between the initial water temperature TWINIT and the initial intake air temperature TAINIT is large, or when PBA <PBFIRE. If the vehicle is in the extremely low load operation state, it is determined that the execution condition is not satisfied, and the determination permission flag FGOFIRE is set to “0” (step S167).

Initial water temperature TWINIT and initial intake air temperature TAI
When the deviation from the NIT is large, the engine temperature is not yet sufficiently lowered and the engine is not started in a cold state, so that the failure determination is prohibited. In addition, during low load operation where PBA <PBIRE is satisfied, the friction of the engine is estimated to be extremely small as compared with normal cold start.
The ignition timing set by the feedback control after shifting to the mode greatly changes in the retard direction, and there is a possibility that it may be erroneously determined to be normal despite the failure, so that the failure determination is prohibited. I have.

FIG. 16 is a time chart showing the transition of the values of the ignition timing IGLOG, the engine speed NE, and the failure determination timer tmFIRE when a failure has occurred. The auxiliary air control valve shown in FIG. 18 valve opening control amount IC
The MD changes in the same manner as in the case shown in FIG. Even if the valve opening control amount ICMD is controlled in this way, if the actual intake air amount does not increase and a failure occurs in which the engine speed NE gradually decreases, the retard correction term IGFPI becomes 0.
In this case, the ignition timing IGLOG is not corrected to the retard side. Therefore, the countdown of the failure determination timer tmFIRE starts at time t11 when the predetermined delay time TMFIREDLY has elapsed. And the judgment time TMFIR
At time t12 when E has elapsed, it is determined that the FIRE mode control has not been executed normally, and the failure flag FF
IRENG is set to "1".

As described above, in the present embodiment, the control in the FIRE mode is correctly executed based on the engine speed NE and the ignition timing IGLOG during the execution of the FIRE mode control (the temperature increase promotion control of the three-way catalyst 16). Is determined, it is possible to quickly detect a failure, for example, the auxiliary air control valve 18 does not perform the valve opening operation corresponding to the valve opening control amount ICMD. Failures can be diagnosed at an early stage, and deterioration of exhaust characteristics can be minimized.

In this embodiment, the auxiliary air passage 17 and the auxiliary air control valve 18 constitute a part of the intake air amount control means, and the ECU 5 comprises a part of the intake air amount control means, the ignition timing control means, and the temperature rise of the catalyst. Means and fault diagnosis means. More specifically, the processing of FIGS. 2, 3, 5, and 7 corresponds to intake air amount control means, the processing of FIGS. 8, 9, 10, and 12 corresponds to ignition timing control means, and the processing of FIG. The processing in FIG. 10 corresponds to the catalyst temperature raising means, and the processing in FIGS. 13 and 14 corresponds to the failure diagnosis means.

The present invention is not limited to the above-described embodiment, and various modifications are possible as follows. (Modification 1) Step S149 of FIG.
Step S149a shown in FIG. In step S149a, the piston of the specific cylinder is moved to the top dead center (T
DC) and a CRK signal pulse generated when
CR generated when TDC (after top dead center) reaches 30 degrees
The time interval MEBURN of the K signal pulse is equal to the determination threshold value BR.
It is determined whether or not it is larger than NFJUD, and MEBURN>
If BRNFJUD, it is determined that the ignition timing has been correctly retarded, and the process proceeds to step S150, while the MEB
If URN ≦ BRNFJUD, it is determined that the retard has not been correctly made, and the process of FIG. 13 is immediately terminated.

This determination is made that if the ignition timing is executed on the advanced side of the top dead center, the engine speed increases during the period of 30 degrees ATDC from the top dead center, whereas the ignition timing is delayed from the top dead center. When executed on the corner side, the timing at which the rotation speed increases is shifted in the retard direction along with this, so that point is checked. That is, when the CRK signal pulse interval MEBURN is large, it indicates that the rotation speed in that period is low, and thus it is determined that the ignition timing is correctly retarded.

Note that this determination is made from A 30 degrees ATDC.
CBU signal pulse interval MEBU corresponding to TDC60 degrees
When the RNA is smaller than the determination threshold, it may be determined that the ignition timing is correctly retarded. In the first modification, the actual ignition timing is determined based on the crank angle position at which the engine rotation speed becomes maximum, and corresponds to the feature described in claim 2.

(Modification 2) Step S149 of FIG.
May be replaced with step S149b shown in FIG. In step S149b, step S1 in FIG.
The stored value IGLOGST stored at 46 and the ignition timing IG
LOG (current value) (= IGLOGST-IGLO)
G) is greater than the determination threshold value DIGJUD2, and if IGLOGST-IGLOG> DIGJUD2, it is determined that the ignition timing has been correctly retarded and the process proceeds to step S150, while IGLOGST-IGL is performed.
When OG ≦ DIGJUD2, it is determined that the retard has not been correctly made, and the process of FIG. 13 is immediately terminated. In this modification, failure determination is performed not based on the ignition timing IGLOG itself but on the amount of change (= IGLOGST-IGLOG), and corresponds to the feature described in claim 3.

[0075]

As described in detail above, according to the first aspect of the present invention, the catalyst temperature raising means is based on at least one of the engine speed and the ignition timing retard amount during the operation of the catalyst temperature raising means. Is diagnosed, it is possible to diagnose the malfunction of the temperature increase accelerating means at an early stage and to suppress deterioration of the exhaust characteristics to a minimum.

According to the second aspect of the present invention, the failure of the catalyst temperature raising means is diagnosed based on the crank angle position at which the engine speed becomes maximum during the operation of the catalyst temperature raising means. It can be determined from the crank angle position at which the ignition timing has been executed whether or not the ignition timing has been accurately executed, and a failure can be determined from the result. Therefore, it is possible to determine a failure in which the actual ignition timing is different from the generation timing of the ignition timing control signal.

According to the third aspect of the present invention, the failure of the catalyst temperature raising means is diagnosed based on the amount of change of the ignition timing during the operation of the catalyst temperature raising means, so that the ignition timing is entirely advanced. Accurate determination can be made even when shifting in the direction or the retard direction.

[Brief description of the drawings]

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

FIG. 2 is a flowchart of a main routine for calculating a control amount (IFIR) of an auxiliary air control valve.

FIG. 3 is a flowchart of a main routine for calculating a control amount (IFIR) of an auxiliary air control valve.

FIG. 4 is a diagram showing a table used in the processing of FIG. 3;

FIG. 5 is a flowchart of a process for determining whether to execute catalyst temperature increase promotion control.

FIG. 6 is a diagram showing a table used in the processing of FIG. 5;

FIG. 7 is a flowchart of a subroutine for calculating a control amount (IFIR) of an auxiliary air control valve.

FIG. 8 is a flowchart of a main routine for executing ignition timing control.

FIG. 9 is a flowchart of a process of determining an execution condition of feedback control of ignition timing.

FIG. 10 is a flowchart of a process for executing feedback control of ignition timing.

FIG. 11 is a diagram showing a table used in the processing of FIG. 10;

FIG. 12 is a flowchart of a process for setting an addition value (ENEFIR) of a target engine speed in catalyst temperature increase promotion control.

FIG. 13 is a flowchart of a process for performing a failure determination.

FIG. 14 is a flowchart of a process of determining an execution condition of a failure determination.

FIG. 15 is a time chart for explaining an operation during execution of catalyst temperature increase promotion control.

FIG. 16 is a time chart for explaining an operation example when catalyst temperature increase promotion control is not executed normally.

FIG. 17 is a view for explaining a modification of the processing in FIG. 13;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake pipe 5 Electronic control unit (intake air amount control means,
Ignition timing control means, catalyst temperature raising means, failure diagnosis means) 11 spark plug 17 auxiliary air passage (intake air amount control means) 18 auxiliary air control valve (intake air amount control means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 43/00 301 F02D 43/00 301L 301B 301K F02P 5/15 F02P 5/15 ECL (72) Invention Person Manabu Niki 1-4-1 Chuo, Wako-shi, Saitama Pref. In Honda R & D Co., Ltd. (72) Inventor Hiroyuki Ando 1-4-1 Chuo in Wako-shi, Saitama F-term in Honda R & D Co., Ltd. ) 3G022 BA01 CA01 CA02 CA03 DA02 EA08 EA09 FA02 FA03 GA01 GA02 GA05 GA07 GA09 GA11 GA12 GA19 GA20 3G084 BA05 BA06 BA17 CA01 CA02 CA03 DA10 DA27 EA07 EA11 EB22 FA01 FA02 FA05 FA06 FA10 FA11 FA20 FA29 FA33 FA01 KA01 KA03 LA00 LA03 LA04 MA01 NA08 ND01 ND21 NE03 NE12 NE17 NE19 NE23 PA07Z PA09Z PA10Z PA11A PA11Z PA15A PA15Z PD02A PD02Z PE0 1A PE01B PE01Z PE03A PE03B PE03Z PE04Z PE05Z PE08Z PF01Z PF08Z

Claims (3)

[Claims] 1. An intake air amount control means for controlling an intake air amount of an internal combustion engine provided with a catalyst in an exhaust system, an ignition timing control means for controlling an ignition timing of the engine, and an intake air after starting the engine. A controller for increasing the amount of fuel and retarding the ignition timing in accordance with the engine speed, wherein the engine speed and the ignition are controlled during the operation of the catalyst temperature increasing means. A control device for an internal combustion engine, comprising: a failure diagnosis unit that diagnoses a failure of the catalyst temperature raising unit based on at least one of a timing retard amount. 2. The failure diagnosis means diagnoses a failure of the catalyst temperature raising means based on a crank angle position at which the engine rotation speed becomes maximum during operation of the catalyst temperature raising means. Item 2. The control device for an internal combustion engine according to Item 1. 3. The apparatus according to claim 1, wherein the failure diagnosis unit diagnoses a failure of the catalyst temperature raising unit based on a variation amount of the ignition timing during operation of the catalyst temperature raising unit. Control device for internal combustion engine.