JP2001132519A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine that can diagnose the malfunction in temperature rising promotion control quickly and control the deterioration in exhaust characteristic in minimum when the temperature rising promotion control of a catalyst combining the increase of intake air quantity and the delay angle control of ignition time is being executed. SOLUTION: The open valve control quantity ICMD of an auxiliary air control valve 18 is decreased to reduce intake air quantity (t11-t12) during executing the temperature rising control of the catalyst. At t12 when the decreasing is finished, if the number of engine revolutions NE and/or the ignition time IGLOG are not within the normal operating scope, it is decided to be a fault.

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. In the control device, the failure diagnosis means for diagnosing failure of the catalyst temperature raising means based on at least one of the ignition timing and the engine speed when the intake air amount is reduced during operation of the catalyst temperature raising means. It is characterized by having.

According to this structure, the failure of the catalyst temperature raising means is diagnosed based on at least one of the ignition timing and the engine speed when the intake air amount is reduced during the operation of the catalyst temperature raising means. Diagnose problems with the heating means early and
Deterioration of exhaust characteristics can be minimized.

[0007]

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.

An engine water temperature (TW) sensor 9 mounted on the main body of the engine 1 is composed of a thermistor or the like, detects an 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 detects 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 shapes input signal waveforms from various sensors, corrects a voltage level to a predetermined level, and converts an analog signal value into a digital signal value. 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 S1, a FIRE mode determination process shown in FIG. 5 is executed. In the FIRE mode determination process,
Permitting transition to FIRE mode or continuation of FIRE mode FIRE mode flag FFI indicated by "1"
Processing such as setting of REON is performed. In step S2, it is determined whether or not the FIRE mode flag FFIREON is "1".
If the shift to the E mode or the continuation of the FIRE mode is not permitted, the process proceeds to step S26 (FIG. 3),
When FIREON = 1 and the transition to the FIRE mode or the continuation of the FIRE mode is permitted,
A transient control flag FFIRQUIT indicating "1" indicating that transient control is being performed immediately after the end of the RE mode is set to "0".
Is set (step S3), and it is determined whether or not a failure determination execution flag FDET indicating "1" to instruct the execution of the failure determination is "1" (step S4). This failure determination execution flag FDET is set in a failure determination process of FIG. 13 described later, and is set to “1” when a predetermined delay time TMFIREDLY has elapsed from the start of the FIRE mode.

Since FDET = 0 at the beginning of the FIRE mode, the counter k incremented in step S9 to be described later is set to "0" (step S5), and FIG.
Is executed (step S6). Then, the FIRE mode control term IFIR calculated in step S6 is set to the engine water temperature control term ITW set according to the engine water temperature TW (the engine water temperature control term ITW is the auxiliary air control valve during idle operation other than the FIRE mode). It is determined whether or not the difference is equal to or less than a lower limit value (ITW-DIFIRL) obtained by subtracting a lower limit value setting predetermined value DIFIRL (for example, a value corresponding to an air flow rate of 100 liters / min) from the control term used in the control of No. 18. (Step S7) If IFIR> ITW-DIFIRL, immediately and IFIR ≦ ITW-DIFI
If it is RL, the FIRE mode control term IFIR is set to its lower limit (ITW-DIFIRL) (step S8), and this processing ends.

When FDET = 1 in step S4, the process proceeds to step S9 and the following steps. First, a process of gradually reducing the FIRE mode control term IFIR of the valve opening control amount ICMD to reduce the intake air quantity is performed, and then the FIRE mode control term IF
A gradual increase process for returning the IR to almost the original value is performed. FIG. 1 to be described later
In the failure determination process of No. 3, a failure determination step is performed when the gradual decrease process ends.

First, in step S9, the counter k is incremented by "1", and then it is determined whether or not the value of the counter k is equal to or greater than a decrease end determination value kDEND (step S10). While k <kDEND, the FIRE mode control term IFIR is decremented by a predetermined decrease value DADEC (step S11), and a decrease end flag FADECEND indicating “1” indicating the end of the decrease processing is set to “0”.
Is set (step S12), and this processing ends. k
If ≧ kDEND, step S10 to step S
13 and the value of the counter k is determined to be the decrease end determination value kDE.
It is determined whether or not ND is larger. If k = kDEND, a decrease end flag FADECEND is set to "1" (step S14), and the process ends. When the flag FADECEND becomes “1”, a failure determination step is executed in the processing of FIG.

From the next time, the answer at step S13 is affirmative (Y
ES), the process proceeds to step S15, and FIRE
The mode control term IFIR is incremented by a predetermined increase value DAINC, and then it is determined whether or not the value of the counter k has reached the increase end determination value kIEND (step S1).
6). This process is immediately terminated while k <kIEND, and when k = kIEND, the failure determination execution flag FD
ET is returned to "0" (step S17), and this processing ends. When FDET = 0, the process returns from step S4 to step S5 and subsequent steps, and is repeated until the FIRE mode ends.

In step S26 of FIG. 3, it is determined whether or not the engine water 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, then , 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, FFIREON = 0 last time
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 IGFPI> IGGFPIQH, and the absolute value of the retardation correction amount IGFPI is small (retarded 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 DFIRQUA, and then the FIRE mode control term IFIR is reduced from the engine coolant temperature control term ITW by the predetermined value DIF for lower limit 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 a succeeding 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) to the adhesion 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)
6B, 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. 14A).
However, in the failure determination mode (time t11 to t13), a gradual decrease process and a gradual increase process of the FIRE mode control term IFIR are executed.

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 determination 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 a value of an up-count timer TM01ACR for measuring an 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, it is determined that NE <NOBJ + NEFPIST. 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 added 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. 14C).

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.

FIG. 14 is a time chart for explaining the above-described intake air amount control and ignition timing control. FIGS. 14A, 14B and 14C show the auxiliary air control valve 1 respectively.
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. At time t11, the failure determination execution flag FDE
T is set to “1”, the mode shifts to the failure determination mode, and the gradual reduction processing of the intake air amount is started. When the gradual reduction processing ends at time t12, the determination steps (S149, S150) of the failure determination processing (FIG. 13) Is executed. Thereafter, the intake air amount is gradually increased, and at time t13, the intake air amount returns to almost the original level, and the failure determination mode ends (the failure determination execution flag FDET is returned to "0"). Time t
Immediately after the end of the FIRE mode in step 4, the intake air amount is controlled to be gradually reduced by the transient control.

The retardation correction term IGFPI changes as shown by the broken line in FIG. 4B, and the ignition timing IGLOG is controlled to be more retarded than the normal control value (IGMAP + IGCR). When the mode shifts to the failure determination mode at time t11, the delay correction term IGFPI increases (decreases the retard amount) with a decrease in the intake air amount, and after time t12, the retard correction term IGFPI increases with the increase in the intake air amount. The angle correction term IGFPRI decreases (the retard amount increases). Thus, the ignition timing IGLOG also changes. At time t13, the failure determination mode ends, and the retard correction term IGFPI almost returns to the original level. Thereafter, 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 output torque increases. The engine speed NE is controlled to be maintained at the target engine speed NEFIR (= NOBJ). After time t4, control is performed so as to gradually shift to the normal control value. Engine speed N
E is controlled by feedback control so as to be equal to the target rotational speed NEFIR from time t2 to t4.
The illustrated example shows a case in which the vehicle starts immediately after time t4, and the vehicle speed VP gradually increases.

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, it is determined whether or not the engine is in the starting mode, that is, whether or not cranking is being performed.
A predetermined delay time TMFIREDLY (for example, 2 seconds) is set in Y and started (step S143), and a failure determination execution flag FDET is set to “0” (step S1).
45), the ignition timing IGLOG is stored as the storage value IGLOGST (step S146), and this processing ends. Here, the predetermined delay time TMFIREDLY is determined, for example, in step S147 after the time when the FIRE mode target rotational speed NEFIR coincides with the normal target rotational speed NOBJ in order to execute the determination during a period in which the change in the engine rotational speed NE is small. It is set to be executed (FIG. 14
(See (a) and (c)).

If the start mode is not set in step S141, that is, if the start is completed, it is determined whether or not the FIRE mode flag is "1" (step S142).
If FFIREON = 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 or not the decrease end flag FADECEND set in step S12 or S14 of FIG. 2 is "1".
As long as ADECEND = 0, this processing is immediately terminated. When FADECEND = 1, step S
149 and S150 are executed. That is, the engine speed NE and the target speed N for normal control
It is determined whether or not the absolute value of the deviation from OBJ is greater than a determination threshold value DNEACT (for example, 100 rpm) (step S149). If | NE-NOBJ |> DNEAACT, the engine speed NE is equal to the target engine speed NOBJ. It is determined that a failure has occurred in which feedback control for controlling the ignition timing is not performed normally so as to match,
A failure flag FFIRENG indicating "1" indicating that a failure in which the operation of the FIRE mode is not performed normally is set to "1" (step S152).

In step S149, | NE-NOBJ | ≤
If it is DNEACT, this ignition timing IGLOG
Of the ignition timing IGLOGST immediately before entering the failure determination mode stored in step S146 (= IGLOGST).
-IGLOGST) is determined to be smaller than the determination threshold value DIGACT (step S150). If the control system is normal, as shown in FIG. 14, the ignition timing IGLOG changes in the advance direction with the decrease in the intake air amount.
The answer to step S150 is negative (NO), and the failure flag FFIRENG is set to "0" (step S15).
1) While ending this processing, IGLOG-IGLOG
When ST <DIGACT, the ignition timing IGLOG
Does not normally change in the advance direction, it is determined that a failure has occurred, and the routine proceeds to step S152.

FIG. 15 is a time chart showing changes in the values of the ignition timing IGLOG, the engine speed NE, and the failure determination timer tmFIRE when a failure has occurred.
The valve opening control amount ICMD of the auxiliary air control valve 18 in FIG.
Are changing in the same manner as in the case shown in FIG. FIG.
Even when the valve opening control amount ICMD is controlled as shown in FIG.
If the actual intake air amount does not increase and the engine speed NE gradually decreases, the valve opening control amount I
In the failure determination mode (time t11 to t12), the ignition timing IGLOG is obtained even if the process for gradually reducing the CMD is executed.
Is maintained at a substantially constant value, and since the engine speed NE is out of the normal range of the target engine speed NOBJ ± DNEACT, it is determined that a failure has occurred.

As described above, in the present embodiment, the valve opening control amount ICMD of the auxiliary air control valve 18 is gradually reduced during the execution of the FIRE mode control (temperature increase promotion control of the three-way catalyst 16) to reduce the intake air amount. Since it is determined whether the control in the FIRE mode is correctly executed based on the engine speed NE and / or the ignition timing IGLOG at that time, for example, the auxiliary air control valve 18 sets the valve opening control amount ICMD. Thus, it is possible to quickly detect a failure such as not performing the valve opening operation corresponding to the above, to diagnose a problem in the catalyst temperature increase promotion control at an early stage, and to suppress deterioration of the exhaust characteristics to a minimum.

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 catalyst temperature increase. 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 corresponds to steps SS4 and S5 in FIG.
And S9 to S17 and the processing of FIG. 13 correspond to the failure diagnosis means.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above-described embodiment, the time t12 when the reduction of the intake air amount is completed.
Immediately in the failure determination step (FIG. 13, step S
149, S150), but it is also possible to wait for a time for the control system to stabilize from the time when the weight reduction is completed, and then to execute the failure determination step.

[0070]

As described above in detail, according to the present invention, when the amount of intake air is reduced during the operation of the catalyst temperature raising means, the temperature of the catalyst temperature raising means is determined based on at least one of the ignition timing and the engine speed. Since the failure is diagnosed, it is possible to diagnose the malfunction of the catalyst temperature raising means at an early stage and to suppress deterioration of the exhaust characteristics to a minimum.

[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 time chart for explaining an operation during execution of catalyst temperature increase promotion control.

FIG. 15 is a time chart for explaining an operation example when catalyst temperature increase promotion control is not executed normally.

[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)

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02D 43/00 301 F02D 43/00 301B 301K F02P 5/15 F02P 5/15 ELK (72) Inventor Manabu Niki Saitama 1-4-1, Chuo, Wako-shi, Pref. Inside Honda R & D Co., Ltd. (72) Inventor Hiroyuki Ando 1-4-1, Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. 3G022 BA01 CA01 CA02 CA03 DA02 EA01 EA09 FA04 FA06 GA01 GA02 GA05 GA07 GA09 GA19 GA20 3G065 AA04 AA11 CA34 CA38 DA04 EA02 GA01 GA09 GA10 GA11 GA26 GA27 GA31 GA41 3G084 BA04 BA06 BA17 CA01 DA27 EA11 EB22 FA33 FA35 3G301 KA01 JA21 KA01 MA18 NA03 NA04 NA05 NC02 ND04 ND05 ND12 ND15 NE03 NE08 NE12 NE20 NE22 PA01A PA07Z PA09Z PA10Z PA11Z PA15A PB03A PB05A PC09Z PD04Z PD12A PE01A PE04Z PE05Z PE08Z PE09A PF01Z PF07Z

Claims (1)

[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. An internal combustion engine having a catalyst temperature increasing means for increasing the amount and retarding the ignition timing in accordance with the engine speed, wherein the intake air amount is reduced during operation of the catalyst temperature increasing means. A controller for diagnosing a failure of the catalyst temperature-raising means based on at least one of the ignition timing and the engine speed at the time of operation.