JP2691489B2 - Internal combustion engine abnormality detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a catalyst device for an internal combustion engine,
The present invention relates to an abnormality detection device including a plurality of detection means for detecting abnormalities such as deterioration and failure of the evaporated fuel purging device and the fuel supply device.

[0002]

2. Description of the Related Art Under an exhaust gas regulation of an internal combustion engine, a catalyst device for detoxifying exhaust gas, an evaporated fuel purging device, and other abnormality detecting means for monitoring each device so that the fuel supply device always functions normally are provided. There is. Each abnormality detecting means detects the state of deterioration and the presence / absence of a failure based on information from various sensors.

Regarding a three-way catalytic converter installed in the exhaust passage of an internal combustion engine to purify exhaust gas by a chemical reaction,
The applicant of the present application has proposed a method for detecting deterioration of a three-way catalyst based on detection values of oxygen concentration sensors (O ₂ sensors) provided on the upstream side and the downstream side of the three-way catalyst (Japanese Patent Application No. 117890). That is, the catalyst deterioration detecting means detects the deterioration of the three-way catalyst based on the detected values of the upstream and downstream O ₂ sensors and the catalyst temperature when the amount of fuel supplied to the internal combustion engine is increased and when it is stopped. I have to.

Further, the abnormality detecting means of the fuel supply device detects the abnormality by monitoring the fluctuation of the air-fuel ratio correction coefficient Ko _{2 in} the feedback control operation state by the normal O ₂ sensor (Japanese Patent Application No. 22229/1990).

Further, the abnormality detecting means of the evaporative fuel purging device for purging the evaporative fuel generated in the fuel tank to the intake system of the internal combustion engine through the canister is in a leak state by performing depressurization processing of the fuel tank in a normal cruise traveling state. Is monitored by the detection value of the tank internal pressure sensor to detect an abnormality.

[0006]

As described above, each abnormality detecting means has an engine operating state suitable for the detection, and it may not be possible to detect two or more abnormality at the same time. Further, if abnormality detection is performed at the same time, one abnormality detection work affects the other abnormality detection, and accurate abnormality detection cannot be performed, resulting in erroneous detection.

The present invention has been made in view of the above point, and an object thereof is to provide an abnormality detecting device for an internal combustion engine in which each abnormality detecting means operates normally.

[0008]

In order to achieve the above object, the present invention provides a catalyst deterioration detecting means and a purge system.
Decompression process and the leak down check after the decompression process.
And fuel for purging evaporative fuel purge system
Engines that supply system abnormality detection means are suitable for detection
An abnormality detection device for an internal combustion engine that detects an abnormality during operation.
And only one of the detection means is detected.
First detection permission means for outputting a permission signal, and the evaporated fuel
When the purge system abnormality detection means is detecting, decompression processing is completed and
Leaker that determines whether or not a breakdown check is in progress
Check check execution determining means and the leak down check.
When the leak down is detected by the execution determination means
The number of catalyst deterioration detection means or fuel system abnormality detection means is small.
The second detection permission hand that outputs the detection permission signal to at least one side
An abnormality detection device for an internal combustion engine including a step .

Each of the first detection permission means is suitable for detection.
Catalyst deterioration detecting means for detecting abnormality in the engine operating state,
Evaporative fuel purge system abnormality detection means and fuel supply system abnormality detection
One of the detection means of the intelligence means
Output only the detection permission signal to two or more detection means at the same time.
Does not give detection permission , the detection work can be performed under the engine operating conditions that are optimal for abnormality detection, and the abnormality can be accurately detected. Especially the introduction of purge system
-It is possible to prevent false detection due to non-introduction.

Then, the evaporative fuel purge system abnormality detecting means is detected.
In the know, the leak down check execution determination means is a decompression process.
Has been completed and it is determined that the leak down check is in progress
In this case, the forced purge cut state may prevent other abnormalities from being detected.
The second detection permission means detects catalyst deterioration because there is no influence
Means or fuel system abnormality detection means to allow detection to improve efficiency
It is possible to detect abnormalities well, except for this case, the first inspection
The knowledge permission means always sends a detection permission signal to only one detection means.
It is possible to output and accurately detect abnormalities. Here, the leak down check is to inspect the leak down because the depressurized state cannot be maintained for a long time if there is a leak in the depressurized purge system.

[0011]

[Embodiment] One embodiment of the present invention shown in FIGS. 1 to 8 will be described below.

FIG. 1 is an overall configuration diagram of a fuel supply control device for an internal combustion engine of this embodiment. In the figure, an engine 1 is an internal combustion engine in which a mixture of fuel and air is sucked from an intake pipe 2 to obtain power by combustion, and exhaust gas after combustion is guided and exhausted by an exhaust pipe 3.

A throttle body 4 is formed in the middle of the intake pipe 2, and a throttle valve 5 is disposed inside the throttle body 4, which is downstream of the throttle valve 5 and slightly upstream of an intake valve (not shown) of the engine 1. A fuel injection valve 6 is provided, and the fuel injection valve 6 is connected to a fuel pump 8 via a fuel supply pipe 7 to supply the fuel in the fuel tank 9 to the intake system.

In such an intake system, the throttle valve opening sensor 11 detects the valve opening θ _TH of the throttle valve 5,
An absolute pressure sensor 13 provided in a branch pipe 12 branched from the intake pipe 2 detects an absolute pressure P _BA in the intake pipe 2, and an intake temperature sensor 14 provided downstream of the intake pipe 2 detects an intake temperature T _A. Is detected.

On the other hand, in the exhaust system, a three-way catalytic converter 15 is provided in the middle of the exhaust pipe 3, and the engine 1
The exhaust gas from the three-way catalyst is redox-reduced to be purified and discharged, and an O ₂ sensor 16 for detecting the oxygen concentration in the exhaust gas on the upstream side and the downstream side of the three-way catalytic converter 15, respectively. 17 are provided.

In addition, the engine 1 is provided with an engine water temperature sensor 18 composed of a thermistor on the cylinder peripheral wall filled with the cooling water of the cylinder block to detect the cooling water temperature T _W , and also around the camshaft (not shown) or crank of the engine 1 An engine speed sensor 19 is attached around the shaft to detect the engine speed Ne.

The vehicle speed sensor 20 detects the vehicle speed V, and the ignition switch sensor 21 detects the ON state of the ignition switch I _G , which indicates that the engine 1 is in the operating state. Further, the fuel tank 9 is provided with a tank internal pressure sensor 22 for detecting the tank internal pressure P _T , a fuel amount sensor 23 for detecting the fuel amount F _V , and a fuel temperature sensor 24 for detecting the fuel temperature T _F.

Each of the above sensors 11, 13, 14, 16-
The detection signal from 24 is input to the electronic control unit ECU 25 and used for various controls.

Next, the evaporative fuel purging device will be described. A vapor pipe 33 communicates the inside of the canister 31 filled with the activated carbon 32 inside the container with the upper space of the fuel tank 9, and the upper space of the canister 31. A purge pipe 34 communicates with the intake pipe 2 downstream of the throttle valve 5.

The vapor pipe 33 is provided with a first control valve 3
5, the first control valve 35 is a two-way valve 38 including a positive pressure valve 36 and a negative pressure valve 37, and a first one-way valve integrally attached to the two-way valve 38. It is composed of a solenoid valve 39. That is, the tip of the rod 39a of the first solenoid valve 39 is attached to the diaphragm 36a of the positive pressure valve 36.

Therefore, the first control valve 35 is connected to the ECU 2
5, when the first solenoid valve 39 is excited, the rod 36a forcibly pushes and opens the diaphragm 36a to open the valve, and the vapor pipe 33 enters the communication state.
When the first solenoid valve 39 is demagnetized, the two-way valve 38
The opening / closing operation is controlled by.

On the other hand, a purge cut valve 40, which is a second control valve, is provided in the conduit of the purge pipe 34. The purge cut valve 40 is an electromagnetic valve, and its opening / closing is controlled by the ECU 25. A hot-wire type flow meter 41 is disposed upstream of the purge cut valve 40 in the purge pipe 34, and the mass flow rate Q _{HW of the} air-fuel mixture containing the evaporated fuel flowing in the purge pipe 34.
Is detected.

Further, a drain pipe 42 extends from a drain port opened at the upper part of the canister 31, and an air introduction port 44
A drain shutoff valve 43 is interposed between and.
The drain shutoff valve 43 is a solenoid valve, and the ECU 25
When the solenoid valve is demagnetized, the drain shut valve 43 is opened and the atmosphere is supplied to the upper space of the canister 31 from the atmosphere introduction port 44. When the solenoid valve is excited, the drain shut valve 43 is opened. The drain shut valve 43 is closed to shut off the communication between the upper space of the canister 31 and the atmosphere.

In the fuel supply control device for the engine 1 as described above, the ECU 25 inputs detection signals from various sensors, and operates in a feedback control operation region or fuel supply cutoff (fuel cut) according to the oxygen concentration in the exhaust gas. Various engine operating states such as an open loop control operating region at the time of high load are determined, and the fuel injection time T _OUT of the fuel injection valve 6 synchronized with the TDC signal pulse from the engine speed sensor 19 is calculated by the following equation. By calculating and controlling the fuel supply amount, the air-fuel ratio is kept optimal.

T _OUT = T _i · K ₁ · K _WOT · Ko ₂ + K ₂ (1) where T _i is a reference value of the injection time of the fuel injection valve 6,
It is searched from the T _i map set according to the engine speed Ne and the intake pipe absolute pressure P _BA . Ko ₂ is an O ₂ feedback correction coefficient and is set according to the oxygen concentration in the exhaust gas detected by the upstream O ₂ sensor 16 during feedback control, and in the open loop control operation region, according to each operation region. It is a coefficient to be set.

In K _WOT , engine 1 has a high load (WOT)
This is a fuel increase coefficient that is set to a value greater than 1.0 when in the operating region. K ₁ and K ₂ are other correction coefficients and correction variables calculated according to various engine parameter signals, respectively, so that various characteristics such as fuel consumption characteristics and engine acceleration characteristics according to the engine operating state can be optimized. It is determined to a predetermined value.

The ECU 25 controls the opening of the fuel injection valve 6 based on the fuel injection time T _OUT obtained as described above.

In the fuel supply control device for controlling the amount of fuel supplied to the engine 1 as described above, the applicant of the present application has already proposed a method of detecting an abnormality in the fuel supply system (Japanese Patent Application No. No. 49080) will be described below with reference to FIGS. 2 and 3. Figure 2 shows the control procedure of the abnormality detection of the fuel supply system (fuel system monitor) Furochi
A chart, and FIG. 3 is a diagram.

First, it is determined whether or not the engine is in an operating state suitable for detecting an abnormality in the fuel supply system (step S1). That is, whether or not the air-fuel ratio feedback (F / B) control is being performed, and whether or not the engine speed Ne is within a predetermined range (for example, 1200 rpm <Ne <40
00 rpm), whether the absolute pressure P _{BA in the} intake pipe is within a predetermined range (for example, 150 mmHg <P _BA <510 mm
Hg), whether the intake air temperature _{T A} is within a predetermined range (e.g., _{0 ℃ <T A <100 ℃} ), whether or not the engine coolant temperature Tw is within a predetermined range (e.g., 70 ℃ <Tw <100 ℃) It is determined whether or not the discharge (purge) of the evaporated fuel from the canister 31 to the intake pipe 2 is stopped (cut) by the purge cut valve 40.

If any of the answers to the determinations in step S1 is negative (No), this program is terminated because the engine is not in an operating state suitable for executing the fuel system monitor, while the answers to the determinations in step S1 are reached. If any of the above is affirmative (Yes), the process proceeds to step S2, and abnormality detection of the fuel supply system is performed by monitoring the change in the value of the air-fuel ratio correction coefficient Ko ₂ .

Hereinafter, description will be made also with reference to FIG. First, when the engine has entered a specific operation area for a predetermined time T
_{When MCHKAVE} has elapsed, an integrated value K _AV that is a learning average value of the correction coefficient Ko ₂ is calculated, and the calculated integrated value K
_AV is (Ko _2AVE + ΔKo _2AVE ) and (Ko
_2AVE- ΔKo _2AVE ) is monitored over a predetermined time period T _EFM to see if it exceeds the range defined by _2AVE- ΔKo _2AVE ).

As shown in FIG. 3A, the integrated value K _AV is, for example, (Ko 2 _AVE + ΔKo) within a predetermined time T _EFM.
2AVE ), the abnormal discriminant coefficient Ko _2AVE having the average value of the correction coefficient Ko ₂ as an initial value is (Ko _2AVE +
αΔKo _2AVE ) is updated (step S2). After that, the coefficient Ko _2AVE is not updated as long as the engine continuously stays in the specific operation range, but once the specific operation range is changed to another range and then the specific operation range is entered again, the result shown in FIG. As shown, the integrated value K _AV is calculated based on the updated value of Ko _2AVE in FIG. 3A, and the integrated value K _AV is calculated based on the updated value of Ko _2AVE (Ko
_2AVE + ΔKo _2AVE ). Then, for example, if the integrated value K _AV exceeds (Ko _2AVE + ΔKo _2AVE ), the coefficient Ko _2AVE becomes the updated Ko.
_{Based on} the value of _2AVE (Ko _2AVE + αΔKo
_2AVE ).

The abnormal discriminant coefficient K thus obtained
o _2AVE is the upper / lower limit discriminant value Ko _{2AVE FSH} ,
Compared with Ko _2AVESL (step S3) Fig. 3
As shown in (c), if the state in which the coefficient Ko _2AVE exceeds the upper limit judgment value Ko _2AVEFSH occurs, and the state continues for a time twice as long as the predetermined time T _EK o _2AVE (the answer in step S3 is affirmative). ) It is determined that an abnormality has occurred in the fuel supply system (step S4).

Next, a method of detecting deterioration of the catalyst of the three-way catalytic converter 15 for purifying exhaust gas by a chemical reaction in the exhaust pipe 3 will be described with reference to the flowchart of FIG. 4 and the explanatory view of FIG.

This catalyst monitor is a three-way catalytic converter 1.
5, the deterioration of the catalyst is judged by observing the change in the output value Vo ₂ of the O ₂ sensor 17 in the O ₂ feedback control state by only the downstream O ₂ sensor 17. FIG. 5 shows the changes in the air-fuel ratio correction coefficient Ko ₂ during the catalyst monitoring and the changes in the output value Vo ₂ of the O ₂ sensor 17 in association with each other.

By increasing / decreasing the correction coefficient Ko ₂ by a predetermined method, the output value Vo ₂ of the O ₂ sensor 17 becomes lean (upper side) and rich side (lower side) with a constant reference value V _REF as a boundary. ) Are alternately inverted.

The correction coefficient Ko ₂ is greatly changed when a predetermined delay time tRD, tLD elapses after the inversion of the output value Vo ₂ of the O ₂ sensor 17, and from this change time to the next inversion time. The time TL and TR are measured.

In the flowchart of FIG. 4, first, it is judged whether or not the engine is in an operating state suitable for detecting deterioration of the three-way catalyst (catalyst monitor) (step S11).
That is, whether the upstream O ₂ sensor 16 and the downstream O ₂ sensor 17 are in the active state, whether the intake air temperature T _A is within a predetermined range (for example, 0 ° C. <T _A <100 ° C.) ,
Whether the engine water temperature Tw is within a predetermined range (for example, 8
0 ° C. <Tw <100 ° C.), whether the engine speed Ne is within a predetermined range (for example, 1650 rpm <Ne <20
50 rpm), whether or not the absolute pressure P _{BA in the} intake pipe is within a predetermined range (for example, 410 mmHg <P _BA <530 mm
Hg), whether or not the traveling speed V of the vehicle is within a predetermined range (for example, 50 km / h <V <60 km / h), and the change ΔV of the traveling speed V of the vehicle for 2 seconds is smaller than 0.8 km / h, for example. Or not.

If any of the answers to the determinations in step S11 is negative (No), it is determined that the engine is not in an operating state suitable for detecting the deterioration, and the process proceeds to step S12, where O
₂ Number of inversions of the output value Vo ₂ of the sensor 17 to the lean side n
TL, the number of reversals nTR to the rich side, the total TLSSUM of the lean side measurement times TL, and the total TRSUM of the rich side measurement times TR are all initialized to "0", and normal fuel control is continued ( Step S13).

In this normal fuel control, the O ₂ feedback control using both the O ₂ sensors 16 and 17 on the upstream side and the downstream side of the three-way catalytic converter 15 is performed, and the condition of step S11 is deviated during the monitoring. If so, the initial learning value is used as Ko ₂ .

When all the conditions are satisfied in step S11, the process proceeds to step S14, it is determined whether or not the number nTR of inversions to the rich side has become a predetermined number or more, and the process proceeds to step S15 until the predetermined number is reached. Determine whether the catalyst monitor has started, and if it has not started,
In step S16, the monitor start process is performed.

In the monitor start processing, the rear O is detected only by the O ₂ sensor 17 on the downstream side of the three-way catalytic converter 15.
_The control is switched to the _two- feedback control. When Vo ₂ is on the rich side, _PRSP is added to the correction coefficient Ko ₂ , and when it is on the lean side, P _LSP is subtracted (time a in FIG. 5).

When the catalyst monitor is started in this way,
Next, from step S15, the process proceeds to step S17, where O ₂
Whether or not the output value Vo ₂ of the sensor 17 has been inverted is determined. If there is inversion, the process proceeds to step S18 to perform the Vo ₂ inversion process, but until there is inversion, the process proceeds to step S19 and the first
The deterioration determination process is performed.

This first deterioration determination process is performed in step S1.
In step 6, add P _RSP to correction coefficient Ko ₂ or P _LSP
After subtracting, it is determined whether or not a predetermined time has passed without the next inversion, and when the predetermined time has passed, that is, when Vo ₂ does not reverse for a predetermined time or more, it is determined to be normal.

Then, it is judged to be normal, and the next step S20
If determined in step S25, the process jumps to step S25 to end the present catalyst monitor and shift to normal fuel control. This is the case where it is judged that the three-way catalytic converter 15 is normal without taking the average of the measured times TL and TR several times.

If Vo ₂ is reversed before the elapse of a predetermined time in step S19, the catalyst system is not determined to be normal (step S20), and the process proceeds to step S21. _It is determined whether or not there is a reversal of ₂ , and if there is no reversal, the process proceeds to step S22 and a reversal waiting process after the start is performed.

That is, as long as there is no inversion of Vo ₂ even before the predetermined time of step S19 has elapsed since the catalyst monitoring started, steps S17, S19, S20 and S2 are performed.
1 and S22 are repeated, and in step S22, the correction coefficient K
I _RSP is added (or I _LSP is subtracted) to o ₂ and the correction coefficient Ko ₂ is gradually increased (or decreased) (FIG. 2).
Point b)).

Then, within the predetermined time of step S19, Vo
_If there is an inversion of ₂ , then steps S17 to S18
Then, the process at Vo ₂ inversion is performed.

In step S18, if the TL or TR is being measured, this inversion determines the current TL or TR, adds it to the previous total TLSUM or TRSUM, and starts the delay time tRD or tLD. Is not being measured (g, k, o in FIG. 5), the delay time tRD or tLD is simply started (c in FIG. 5). Step S18
Then, the number of times of inversion nTL, nTR is incremented.

After the inversion of Vo _2, the process proceeds from step S17 to steps S19, S20 and S21 and then to step S23, where the Vo ₂ inversion waiting process is performed. That is, until the delay times tRD and tLD elapse, I _RSP continues to add or subtract I _LSP to Ko ₂ (at d, h, l and p in FIG. 5), and at the same time as the delay time elapses, T
L, starts the measurement of TR, _{P LSP} to Ko ₂
Is subtracted (e, m in FIG. 5) or _PRSP is added (i, q in FIG. 5) to make a large change, and I _LSP is subtracted from Ko ₂ during TL and TR measurement thereafter (f, n in FIG. 5). ) Or I
_RSP is added (j, r in FIG. 5) and gradually changed.

After that, Ko ₂ is gradually increased or decreased in step S23, and if Vo ₂ is inverted, TL and TR are determined in step S18, TLSUM and TRSUM are calculated, and delay times tRD and tLD are started. Next, step S23 is executed again, and the delay time tR
The measurement of TL and TR is started at the same time as the passage of D and tLD.

By repeating this, when the number nTR of inversions of Vo _{2 to} the rich side reaches a predetermined number, step S14
From step S24, the second deterioration determination process is performed. In this step S24, the average value TL of TL and TR
SUM / nTL and TRSUM / nTR are added and divided by 2 to calculate an average time T _CHK, which is compared with a determination value. When the average time T _CHK is greater than the determination value, the catalyst system is determined to be normal, and when the average time T _CHK is less than the determination value. It is judged to be abnormal. That is, it is determined that the catalyst has deteriorated.

The reference value for this comparison is determined by a table search based on the catalyst temperature of the three-way catalytic converter 15.

After step S24, step S
Proceeding to 25, the catalyst monitor ends and the normal fuel control is resumed. This normal fuel control is O ₂ feedback control using both the upstream and downstream O ₂ sensors 16 and 17 of the three-way catalytic converter 15, and the initial value of the correction coefficient Ko ₂ is the learned value of Ko _2. To use.

Next, a method of detecting an abnormality in the evaporated fuel purge device (purging system monitor) will be described with reference to the flowchart of FIG. 6 and the explanatory view of FIG.

First, it is determined whether or not the engine is in an operating state suitable for executing the purge system monitor (step S31).

[0057] That is whether the intake air temperature _{T A} is within a predetermined range (e.g., _{50 ℃ <T A <90 ℃} ), to determine the engine coolant temperature Tw is within a predetermined range (e.g., 70 ℃ <Tw <90 ℃) It is determined whether the engine is warmed up, and then the engine speed Ne is within a predetermined range (for example, 200
0 rpm <Ne <4000 rpm), absolute pressure P in the intake pipe
Is _BA within a predetermined range (for example, -410 mmHg <
P _BA <-150 mmHg), throttle valve opening θ _TH
Is within a predetermined range (for example, 1 ° <θ _TH <5 °),
Is the vehicle speed V within a predetermined range (for example, 53 km / h <V
<61 km / h) and whether the vehicle is in the cruise traveling state or not and determines whether the operating state is the stable cruise traveling state. For example, it is ±
It is determined whether or not the vehicle speed fluctuation within 0.8 km / sec continues for 2 seconds.

Next, it is determined whether the tank internal pressure sensor 22 and various valves operate normally and whether the mass flow rate Q _HW passing through the purge pipe 34 is sufficiently secured by the hot wire type flow meter 41.

If any answer to each of the determinations in step S31 is negative (No), it is determined that the engine is not in an operating state suitable for detecting an abnormality in the purge system, and the process proceeds to step S32, and all the answers to the determinations are positive. If (Yes), it means that the engine is in an operating state in which the abnormality of the purge system is detected, and the process proceeds to step S34.

The flow chart of FIG. 6 will be described below with reference to FIG. 7 shows the first solenoid valve 3
FIG. 9 is a diagram showing operation patterns of the drain shut valve 43 and the purge cut valve 40 and a change state of the tank internal pressure P _T , which shows changes in the tank internal pressure during normal operation, during atmospheric release, during decompression processing, and during leak down check. Four stages are shown.

Immediately after the engine is started, the engine is not in the operating state for detecting the abnormality of the purge system, so the routine proceeds from step S31 to step S32, and the first timer tmPTO is set to the predetermined time T1. The predetermined time T1 is a tank internal pressure P _T when the tank internal pressure P _T is opened to the atmosphere is set to a sufficient time to stabilize (e.g., 30 seconds).

Then, after the first timer tmPTO is started, the routine proceeds to step S33, where the evaporated fuel purge system is set to the normal purge mode. That is, the first electromagnetic valve 39 is turned off so that the vapor pipe 33 is automatically controlled to be opened and closed by the two-way valve 38, the drain shut valve 43 is opened, and air can be taken in through the drain pipe 42. The purge cut valve 40 is opened to enable purging.

In the normal purge mode, the evaporated fuel generated in the fuel tank 9 is introduced into the canister 31 through the vapor pipe 33 by opening the positive pressure valve 36 of the two-way valve 38 due to the increase in tank internal pressure and adsorbed to the activated carbon 32. The evaporated fuel thus adsorbed is separated from the activated carbon 32 together with the air taken in from the drain pipe 42 by the negative pressure in the intake pipe 2, and is purged into the intake pipe 2 via the purge pipe 34. The above is the normal purge state in step S33, which corresponds to the stage of normal operation in FIG.

When the condition in step S31 is satisfied, the process proceeds to step S34, and the first timer t
It is determined whether or not the mPTO has become "0". Since it is not "0" at the beginning, the routine proceeds to step S35, where the tank internal pressure is released to the atmosphere.

That is, the first solenoid valve 39 is turned on to forcibly open the first control valve 35 to make the inside of the fuel tank 9 in communication with the atmosphere via the canister 31 to bring the tank internal pressure to atmospheric pressure. Enter the stage of opening to the atmosphere in.

Then, the second timer tmPTD is set to the predetermined time T2 (step S36). This predetermined time T2
Is a time sufficient to determine that there is a leak in the purge system when the tank internal pressure P _T is not reduced to the predetermined reference value P _{TLVL within a} certain time after the depressurization process is started.

Steps S31 and S34 to S36 are repeated to sufficiently open the atmosphere, and the first timer tmPTO
Becomes 0, the process proceeds from step S34 to step S37. In step S37, it is determined whether or not the pressure reducing process is completed, and until the pressure reducing process is completed, step S3
Proceed to 8.

[0068] At step S38, the it is determined whether or not the tank internal pressure _{P T} is equal to or less than a predetermined reference value _{P TLVL} (eg -20 mmHg) is because initially the tank internal pressure _{P T} is open to the atmosphere, the process proceeds to step S39 The tank internal pressure is reduced.

That is, when the drain shutoff valve 43 is closed by turning on the second solenoid valve 52, the drain pipe 4
Since the communication with the atmosphere via 2 is cut off, the canister 31 and the fuel tank 9 are decompressed by the negative pressure in the intake pipe 2 via the purge pipe 34. Enter the stage.

Then, it is judged whether or not the second timer tmPTD has become "0" (step S40), the tank internal pressure P _T has not _decreased to the predetermined reference value P _TLVL, and the predetermined time T2 has elapsed and "0". If it is, there is a risk of leakage in the purge system, so jump to step S45 and make an abnormality determination. In this case, it is immediately determined to be abnormal.

Step 4 is performed while the predetermined time T2 has not elapsed.
1 and proceeds to the third timer tm for leak down check
PTDC is set to a predetermined time T3. The predetermined time T3 is set to the time required for the leak down check, for example, 30 seconds.

When the tank internal pressure P _T falls to the predetermined reference value P _TLVL , the process proceeds from step S38 to step S42, the pressure reducing process is set to end, and the process proceeds to step S43. After the decompression process is set to end, the process directly proceeds from step S37 to step S43. In step S43, the third
It is determined whether or not the timer tmPTDC has become “0”, and whether or not the time T3 required for the leak down check has elapsed.

Initially, the third timer tmPTDC is "0".
Therefore, the flow advances to step S44 to enter the leak down check state. That is, the purge cut valve 40 is turned off to close the purge pipe 34 that connects the intake pipe 2 and the canister 31, thereby closing the purge cut valve 40 of the fuel tank 9, the vapor pipe 33, the canister 31, and the drain pipe 42. The upstream portion and the portion of the drain pipe 42 on the canister 31 side of the Dorn shut valve 43 form one sealed space, and the inside is depressurized to a predetermined pressure.

Therefore, if there is a gap in the sealed pipe connection portion of the purge system, valves, or the seal portion (for example, filler cap) of the fuel tank 9, there is a large change in the tank internal pressure P _T. In the normal state where there is no leak from the purge system as shown in the leak down check of No. 7, there is almost no change in the tank internal pressure P _T as shown by the chain double-dashed line, but when there is a leak, as shown by the solid line Since the change in the internal pressure P _T is large, it is possible to determine the abnormality of the purge system.

At the time of this leak down check, if the third timer tmPTDC becomes "0" after the time T3 required for the leak down check has passed, step S
It progresses from 43 to step S45.

At this point, the abnormality determination is performed. The abnormality judgment is
The tank internal pressure P _T is the abnormality determination value P _TJDG value (for example, −1.
0 mmHg) to determine whether the determination value P
If it is larger than the _TJDG value, it is determined that a large amount of fuel vapor will leak, and the purge system is determined to be abnormal, and the determination value P _TJDG
If smaller than the value, it is determined to be normal.

After this abnormality determination, the normal purge state is restored (step S33), and the abnormality detection of the evaporated fuel purge system is completed.

As described above, the abnormality detection of the fuel supply system (fuel system monitor), the deterioration detection of the three-way catalyst (catalyst monitor), and the abnormality detection of the evaporated fuel purge system (purge system monitor) are normally performed. Since the engine operating states for performing the above are different, it is impossible to perform them at the same time, or even if they can be performed, the execution of one monitor affects the other monitor, and accurate abnormality detection cannot be expected.

Therefore, in the present embodiment, the first detection permission means and the second detection permission means perform the adjustments during the detection of each abnormality in accordance with the flowchart of FIG.

In the judgment of steps 61, 62, 63 and 65
Then, one of the monitors is detected by the first detection permission means.
Implementation of one monitor is permitted. First, it is determined whether or not the purge control for the fuel system monitor is being executed (step S61), and if it is being executed, the process jumps to step S70 to permit only the fuel system monitor to be executed, and the other catalyst monitors and Implementation of purge system monitor and O ₂ sensor monitor is not allowed.

If the purge control for fuel system monitoring is not being executed in step S61, the process proceeds to step S62.
O on the downstream side of the three-way catalytic converter 15 for monitoring the catalyst
₂ It is determined whether the feedback fuel control by the sensor 17 is being performed, and if it is being performed, step S
Jumping to 69, only the catalyst monitor is allowed to be executed, and the other monitors are not allowed to be executed.

In step S62, the downstream O ₂ sensor 17
If feedback control is not being performed by step S63
Then, it is determined whether or not the depressurization process has already been performed for the abnormality detection of the purge system in the current traveling, and if the depressurization process has already been performed, the process proceeds to step S64 and it is determined whether or not the leak down check is being performed.

When the purge system is being monitored for the first time in this running, the pressure reducing process is performed (step S
63), or not it is in the leak down check leakage
Enter the judgment of the down-check judgment means (step S6
4) Next, if leak down check is in progress, step S
Proceeding to 67 , the execution of all monitors is permitted by the second detection permitting means .

That is, during the leak down check, the purge cut valve 40 is closed and the evaporative fuel purge does not affect the execution of the catalyst monitor, the fuel system monitor and the O ₂ sensor monitor. I permit it.

Then, once the leak down check is finished, it is judged whether or not there is an abnormality in the purge system, and when the abnormality detection of the purge system is finished, the routine proceeds to step S68, and execution of the purge system monitor is not permitted and other Anomaly detection is permitted. That is, the abnormality detection of the purge system is carried out only once in one traveling.

If it is determined in step S63 that the purge system abnormality detection has not been performed, or if the purge system abnormality detection has been performed but the pressure reduction process has not yet been completed, step S6 is performed.
In step 5, it is determined whether or not the pressure reducing process is being performed. If the pressure reducing process is being performed, the process proceeds to step S66, in which only execution of the purge system monitor is permitted and continued, and other monitors are not permitted.

If the pressure reduction processing is not being performed, the purge system monitor has not been executed yet, and other monitors can be executed. Therefore, the process proceeds to step S67, and execution of all monitors is permitted.

As described above, among the abnormality detection of the evaporative fuel purge system, all the monitoring may be permitted during the leak down check, and the abnormality detection can be performed efficiently.

[0089] In the case of non-leak down check is carried out of the other monitor when one of the monitors is being carried out is not permitted, affected by implementation of the other monitor
Therefore, the abnormality can be detected accurately.

[0090]

According to the present invention, the first detection permitting means causes a leak.
When one of the detection means is operating except during the down check, the execution of the other detection means is not permitted, so that the optimum operating state of each detection means,
Moreover, the abnormality can be accurately detected without being affected by other detecting means.

During the leak down check, the purge
By the second detection permitting means for being Tsu bets, to allow operation of the other abnormality detection, and more abnormality detection can be efficiently performed.

[Brief description of the drawings]

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

FIG. 2 is a flowchart showing a control procedure for detecting an abnormality in a fuel supply system.

FIG. 3 is a schematic explanatory diagram of the control of FIG.

FIG. 4 is a flowchart showing a control procedure for detecting catalyst deterioration.

5 is a schematic explanatory diagram of the control of FIG.

FIG. 6 is a flowchart showing a control procedure for detecting an abnormality in an evaporated fuel purge system.

FIG. 7 is a schematic explanatory diagram of the control of FIG.

FIG. 8 is a flowchart showing a control procedure for performing execution adjustment of various abnormality detections.

[Explanation of symbols]

1 ... Engine, 2 ... Intake pipe, 3 ... Exhaust pipe, 4 ... Throttle body, 5 ... Throttle valve, 6 ... Fuel injection valve, 7 ... Fuel supply pipe, 8 ... Fuel pump, 9 ... Fuel tank, 11 ... Throttle valve Position sensor, 12 ... Branch pipe, 13 ... Absolute pressure sensor,
14 ... Intake air temperature sensor, 15 ... Three-way catalytic converter, 16, 17 ...
O ₂ sensor, 18 ... Engine water temperature sensor, 19 ... Engine speed sensor, 20 ... Vehicle speed sensor, 21 ... Ignition switch sensor, 22 ... Tank internal pressure sensor, 23 ... Fuel amount sensor, 24 ... Fuel temperature sensor, 25 ... ECU, 31 ... Canister, 32 ... Activated carbon, 33 ... Vapor pipe, 34 ... Purge pipe, 35 ... First control valve, 36 ... Positive pressure valve, 37 ... Negative pressure valve, 38 ... 2
Directional valve, 39 ... First solenoid valve, 40 ... Purge cut valve, 41 ...
Heat wire type flow meter, 42 ... Drain pipe, 43 ... Drain shut valve, 44 ... Atmosphere inlet.

Front Page Continuation (72) Inventor Masayoshi Yamanaka 1-4-1 Chuo, Wako-shi, Saitama Inside of Honda R & D Co., Ltd. (56) Reference JP-A-63-29050 (JP, A) JP-A-3- 3958 (JP, A) JP 4-17758 (JP, A) JP 4-112950 (JP, A) JP 3-194145 (JP, A) JP 3-107562 (JP, A) JP-A-2-105072 (JP, A) JP-A-3-57862 (JP, A) JP-A-1-106948 (JP, A) JP-A-2-33446 (JP, A)

Claims (1)

(57) [Claims] 1. A catalyst deterioration detecting means and a depressurizing process of a purge system.
And its decompression process followed by a leakdown check
Evaporative fuel purge system abnormality detecting means and the fuel supply system abnormality detection means that is, the engine operating state suitable for detection respectively
In an abnormality detection device for an internal combustion engine that detects an abnormality , only one of the detection means has a detection permission signal.
Detection permission means for outputting a signal and the evaporative fuel purge system abnormality detection means are detecting,
And whether or not the leak down check is in progress
And leak down check execution determination means for, Rikuda by the leak down check execution determination means
When detecting that the catalyst is
A detection permission signal is sent to at least one of the fuel system abnormality detection means.
An abnormality detection device for an internal combustion engine, comprising: a second detection permission means for outputting .