JPH05180093A - Vaporized fuel processing device for internal combustion engine - Google Patents

Abstract

PURPOSE:To accurately and correctly detect abnormality by leaving a fluctuation amount (vapor generation amount) as detected of tank internal pressure before performing a pressure reducing process, and deciding the abnormality of a vapor fuel discharge suppressing system based on the vapor generation amount and the pressure fluctuation amount after the pressure reducing process. CONSTITUTION:A device is provided with a vapor fuel discharge suppressing system 11 comprising the first control valve 28 interposed in a fuel vapor circulating path 27 and the second control valve 36 interposed in a purge passage 10. The device comprises the third control valve 40 for opening/closing an air suction port 25 of a canister 26 and a pressure reduction processing means 5 for controlling the first to third control valves 28, 36, 40 to plate the vapor fuel discharge suppressing system 11 in a predetermined negative pressure condition. Further, an abnormality deciding means 5 or the like for deciding abnormality of the vapor fuel discharge suppressing system 11 is provided. A fluctuation amount of tank internal pressure is detected before performing a pressure reducing process, to decide whether the abnormality is provided or not by a discriminating value determined in accordance with a pressure reduction processing time. In this way, the abnormality of the vapor fuel discharge suppressing system 11 can be accurately and correctly detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporative fuel treatment apparatus for an internal combustion engine, and more particularly, to an abnormal evaporative fuel discharge inhibiting system for releasing (purging) evaporative fuel generated in a fuel tank of an internal combustion engine to an intake system. The present invention relates to an evaporated fuel processing device for an internal combustion engine that can be diagnosed.

[0002]

2. Description of the Related Art Conventionally, a fuel tank, a canister having an intake port, a first control valve interposed in a fuel vapor flow passage connecting the canister and the fuel tank, and the canister. An evaporative fuel treatment apparatus for an internal combustion engine is widely used, which includes an evaporative emission control system that includes a second control valve interposed in a purge passage that connects an intake system of the internal combustion engine.

In this type of device, the evaporated fuel is temporarily stored in the canister, and the stored evaporated fuel is discharged (purged) to the intake system of the engine.

Further, as a method for determining an abnormality in the evaporated fuel processing apparatus of this type, the evaporated fuel discharge restraint system is forcibly set to a predetermined negative pressure state, and the tank internal pressure after the negative pressure state is set. The applicant of the present application has already proposed a method for determining whether or not there is an abnormality by measuring a change with time (Japanese Patent Application No. 3-262857).

[0005]

However, in the abnormality determining method in the above-described evaporative fuel treatment apparatus, the fuel vapor leaks due to the fluctuation of the internal pressure after the evaporative fuel discharge inhibiting system is brought to a predetermined negative pressure state. Whether or not there is a large amount of fuel vapor in the fuel tank, the pressure fluctuation during leak down check is large and the system is normal because the system determines whether the system is abnormal. Nevertheless, a new problem has arisen that abnormalities are detected.

The present invention has been made in view of the above problems, and it is possible to accurately and accurately detect an abnormality in the vapor fuel discharge suppression system even when a large amount of fuel vapor is generated in the fuel tank. It is an object of the present invention to provide a vapor fuel processing apparatus for an internal combustion engine that can detect the above.

[0007]

In order to achieve the above object, the present invention provides a fuel tank, a canister having an intake port, and a fuel vapor flow passage connecting the canister and the fuel tank. Evaporative fuel for an internal combustion engine having an evaporative emission control system including a mounted first control valve and a second control valve installed in a purge passage connecting the canister and an intake system of the internal combustion engine In the processing device,
An operating state detecting means for detecting an operating state of the engine; a third control valve for opening and closing the intake port of the canister;
The tank internal pressure detecting means for detecting the internal pressure of the fuel tank, the first variation amount detecting means for detecting the variation amount of the tank internal pressure by controlling the opening and closing of the first control valve, and the engine by the operating state detecting means. Pressure reducing means for controlling the first to third control valves to bring the evaporative emission control system into a predetermined negative pressure state when the operation is detected,
Of the first and second fluctuation amount detecting means for detecting the fluctuation amount of the internal pressure from the negative pressure state of the evaporated fuel discharge system by closing the control valve of An abnormality determination processing system including an abnormality determination means for determining an abnormality of the evaporated fuel emission suppression system based on a detection result, and a determination for determining an abnormality of the evaporated fuel emission suppression system by the abnormality determination means. The value is determined according to the pressure reduction processing time in the pressure reduction processing means.

Further, according to the present invention, an operating condition detecting means for detecting an operating condition of the engine, a third control valve for opening and closing the intake port of the canister, and a tank internal pressure detecting device for detecting an internal pressure of the fuel tank. Means, first variation amount detection means for controlling the opening and closing of the first control valve to detect the variation amount of the tank internal pressure, and the first operation amount detection means when the operation of the engine is detected. To a pressure reducing means for controlling the third control valve to bring the vaporized fuel emission restraining system into a predetermined negative pressure state, and the second control valve to close the negative pressure of the vaporized fuel emission restraining system. Second variation amount detecting means for detecting the variation amount of the internal pressure from the pressure state, fuel amount detecting means for detecting the fuel amount in the fuel tank, the first and second variation amount detecting means, and the above Based on the detection result of the fuel amount detection means May be characterized by having an abnormality determination means that an abnormality determination processing system consisting of determining an abnormality of the serial evaporative emission control system.

In the fuel vapor processing apparatus for an internal combustion engine, the first fluctuation amount detecting means controls the opening / closing of the first control valve to detect the fluctuation amount of the tank internal pressure.

Further, the present invention is characterized in that purging is performed for a predetermined time before starting the processing by the abnormality judging processing system.

[0011]

According to the above-mentioned structure, the fluctuation amount of the tank internal pressure can be detected before the depressurization process is performed, and the steam fuel discharge inhibiting system can change the fluctuation amount (steam generation amount) and the tank internal pressure after the depressurization process. Based on the amount, it is determined whether or not there is an abnormality based on the discriminant value determined according to the pressure reduction processing time.

Further, according to the second aspect of the present invention, the abnormality of the evaporative fuel discharge system is determined based on the amount of fuel in the fuel tank, the amount of steam generated, and the amount of pressure fluctuation after pressure reduction processing.

Further, by carrying out purging for a predetermined time before starting the processing by the abnormality determination processing system, the abnormality determination processing is executed after the fuel vapor adsorbed and stored in the canister is reduced.

[0014]

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

FIG. 1 is an overall configuration diagram showing an embodiment of an evaporated fuel processing apparatus for an internal combustion engine according to the present invention.

In the figure, reference numeral 1 is an internal combustion engine having, for example, four cylinders (hereinafter simply referred to as "engine"), in which an intake pipe 2 of the engine 1 is provided with a throttle body 3 inside thereof. A throttle valve 3'is provided. Further, the throttle valve 3 ′ has a throttle valve opening (θ
TH) sensor 4 is connected and outputs an electric signal according to the opening degree of the throttle valve 3 ′ and supplies it to an electronic control unit (hereinafter referred to as “ECU”) 5.

The fuel injection valve 6 is provided for each cylinder in the middle of the intake pipe 2 and slightly upstream of an intake valve (not shown) between the engine 1 and the throttle valve 3 '. Further, each fuel injection valve 6 is connected to a fuel pump 8 via a fuel supply pipe 7 and electrically connected to the ECU 5,
A signal from 5 controls the valve opening timing of fuel injection.

A negative pressure communication passage 9 and a purge pipe 10 are provided branching from the intake pipe 2 downstream of the throttle valve 3 ', and the negative pressure communication passage 9 and the purge pipe 10 are connected to a fuel vapor discharge inhibiting system 11 described later. It is connected to the.

Further, a branch pipe 12 is provided downstream of the purge pipe 10 of the intake pipe 2, and an absolute pressure (PBA) sensor 13 is arranged at the tip of the branch pipe 12. Also,
The PBA sensor 13 is electrically connected to the ECU 5,
Absolute pressure PB in the intake pipe 2 detected by the A sensor 13
A is converted into an electric signal and supplied to the ECU 5.

An intake air temperature (TA) sensor 14 is mounted on the intake pipe 2 downstream of the branch pipe 12, and the TA sensor 1
The intake air temperature TA detected by 4 is converted into an electric signal,
It is supplied to the ECU 5.

An engine water temperature (TW) sensor 15 composed of a thermistor or the like is attached to the cylinder peripheral wall filled with cooling water of the cylinder block of the engine 1, and the engine cooling water temperature TW detected by the TW sensor 15 is converted into an electric signal. It is converted and supplied to the ECU 5.

An engine speed (NE) sensor 16 is provided around a cam shaft or crank shaft (not shown) of the engine 1.
Is attached.

The NE sensor 16 outputs a signal pulse (hereinafter referred to as a "TDC signal pulse") at a predetermined crank angle position every 180 ° rotation of the crankshaft of the engine 1, and the TDC signal pulse is supplied to the ECU 5. ..

The transmission 17 is interposed between wheels (not shown) and the engine 1, and the wheels are driven by the engine 1 via the transmission 17.

A vehicle speed (VSP) sensor 18 is attached to the wheel, and the vehicle speed VSP detected by the VSP sensor 18 is converted into an electric signal and supplied to the ECU 5.

An oxygen concentration sensor (hereinafter referred to as "O ₂ sensor") 20 is provided in the exhaust pipe 19 of the engine 1.
Is provided, the oxygen concentration in the exhaust gas detected by the O ₂ sensor 20 is converted into an electric signal, and the ECU 5
Is supplied to.

An ignition switch (IGSW) sensor 21 is an IG indicating that the engine 1 is operating.
The ON state of the SW is detected and its electric signal is supplied to the ECU 5.

Therefore, the fuel vapor discharge restraint system 11 (hereinafter referred to as "discharge restraint system") has a fuel tank 23 having a filler cap 22 which is opened at the time of refueling the fuel and an activated carbon 24 as an adsorbent. And a canister 26 provided with an intake port (outside air intake) 25 at the top,
A fuel vapor flow passage 27 connecting the canister 26 and the fuel tank 23, and a first control valve 28 interposed in the fuel vapor flow passage 27 are provided.

The fuel tank 23 is connected to the fuel injection valve 6 via a fuel pump 8 and a fuel supply pipe 7, and a tank internal pressure (PT) sensor 29 and a fuel amount (FV) sensor are provided above the fuel tank 23. 30 is provided, and a fuel temperature (TF) sensor 31 is provided on the side thereof.
In addition, these PT sensor 29, FV sensor 30 and TF
All the sensors 31 are electrically connected to the ECU 5. The PT sensor 29 detects the internal pressure (PT) of the fuel tank 23 and supplies the electric signal to the ECU 5,
The FV sensor 30 detects the amount of fuel (FV) in the fuel tank 23, supplies the electric signal to the ECU 5, and further outputs TF.
The sensor 31 detects the fuel temperature (TF) in the fuel tank 23 and supplies the electric signal to the ECU 5.

The first control valve 28 includes a two-way valve 34 consisting of a positive pressure valve 32 and a negative pressure valve 33, and the two-way valve 3
4 and a first electromagnetic valve 35 integrally attached to the No. 4 unit.
That is, the tip of the rod 35a of the first solenoid valve 35 is abutted on the diaphragm 32a of the positive pressure valve 32, and the first control valve 28 is the two-way valve 34 and the first solenoid valve 35.
And are integrated. Further, the first electromagnetic valve 35 is electrically connected to the ECU 5, and the operating state of the first electromagnetic valve 35 is controlled by a signal from the ECU 5. And
When the first solenoid valve 35 is excited (turned on), the two-way valve 34
Positive pressure valve 32 is forcibly pushed open to open the first control valve 28, while the first solenoid valve 35 is demagnetized (OFF).
During this time, the opening / closing operation of the first control valve 28 is controlled by the two-way valve 34.

Purge pipe 10 connected to canister 26
A purge control valve 36 (second control valve) is provided in the conduit of the ECU 5, and the solenoid of the purge control valve 36 is the ECU 5
It is connected to the. The purge control valve 36 is the ECU
The valve opening amount is controlled linearly according to the signal from the control unit 5. That is, the ECU 5 outputs a desired control amount to control the opening amount of the purge control valve 36.

Further, the canister 26 and the purge control valve 36
A hot-wire type flow meter (mass flow meter) 37 is provided between and. This hot-wire type flowmeter 37 utilizes the fact that when a platinum wire heated by passing an electric current is exposed to an air stream, its temperature decreases and its electric resistance decreases, and its output characteristic is the concentration of fuel vapor, It changes according to the flow rate and the purge flow rate, and supplies to the ECU 5 output signals according to these changes.

A drain shut valve 38 is provided in the negative pressure communication passage 9 connected to the intake port 25 of the canister 26, and a second solenoid valve 39 is provided downstream of the drain shut valve 38. The drain shut valve 38 and the second solenoid valve 39 constitute a third control valve 40.

The drain shut valve 38 is connected to the diaphragm 4
1 to define an atmospheric chamber 42 and a negative pressure chamber 43. Further, the atmosphere chamber 42 includes a first chamber 44 having a valve body 44a therein and a second chamber 45 having an atmosphere introducing port 45a.
And a narrowed portion 47 connecting the second chamber 45 and the first chamber 44, and the valve body 44a is connected to the diaphragm 41 via a rod 48. Further, the negative pressure chamber 43 is
A spring 49 that is in communication with the second solenoid valve 39 and that elastically urges in the direction of arrow A is seated.

In the second solenoid valve 39, when the solenoid is demagnetized (OFF), the atmosphere can be introduced into the negative pressure chamber 43 through the atmosphere supply port 50, and when the solenoid is excited (ON). Intake pipe 2 through negative pressure communication passage 9
It is possible to communicate with. Incidentally, 51 is a check valve.

Thus, the ECU 5 shapes the input signal waveforms from the various sensors described above, corrects the voltage level to a predetermined level, and converts the analog signal value into a digital signal value. A central processing circuit (hereinafter referred to as "CPU"), storage means for storing a calculation program executed by the CPU, calculation results, etc., the fuel injection valve 6, the first and second solenoid valves 35, 39, and the purge. And an output circuit for supplying a drive signal to the control valve 36.

FIG. 2 is a diagram showing the operating patterns of the first and second solenoid valves 35, 39, the drain shut valve 38, and the second control valve 36 in this embodiment, and the changing state of the tank internal pressure PT at that time. So, this operation pattern is ECU5
It is executed by a signal from (CPU).

First, during normal operation (normal purge mode) (shown in FIG. 2), the first solenoid valve 35 is turned on, while the second solenoid valve 39 is turned off and the IGSW is turned on. Is turned on and the operation of the engine is detected by the IGSW sensor 18, the purge control valve 36 is turned on and opened. Then, the evaporated fuel generated in the fuel tank 23 flows into the canister 26 through the fuel vapor flow passage 27, and is temporarily adsorbed and stored by the adsorbent 24 of the canister 26. Then, as described above, during normal operation, the second electromagnetic valve 39 is off, so the drain shut valve 38 is in an open state, the outside air is supplied to the canister 26 from the air inlet 45a, and the fuel vapor flowing into the canister 26 is supplied. Is purged into the purge pipe 10 through the second control valve 36 together with the outside air. When the fuel tank 23 is cooled due to the influence of the outside air and the negative pressure in the fuel tank 23 increases,
The negative pressure valve 33 of the two-way valve 34 opens and the canister 2
The fuel vapor stored in 6 is returned to the fuel tank 23.

However, when the engine 1 satisfies a predetermined monitor permission condition, which will be described later, the first and second electromagnetic valves 35 and 39 and the purge control valve 36 operate as follows, and the emission restraint system 11 Diagnose abnormalities.

First, the tank internal pressure PT is opened to the atmosphere (shown by FIG. 2). That is, the first solenoid valve 35 is kept in the ON state to bring the fuel tank 23 and the canister 26 into communication with each other, and the second solenoid valve 39 is kept in the OFF state to open the drain shut valve 38. Is maintained, and the purge control valve 36 is maintained in the open state (on state) to open the tank internal pressure PT to the atmosphere.

Next, the fluctuation amount of the tank internal pressure is measured (shown by FIG. 2).

That is, the second solenoid valve 39 is maintained in the off state to maintain the drain shut valve 38 in the open state and the purge control valve 36 in the open state, while the first solenoid valve 35 is maintained. Is turned off to measure the fluctuation amount of the tank internal pressure from the time of opening to the atmosphere, and check the steam generation amount in the fuel tank 23.

Next, the pressure of the emission control system 11 is reduced (see FIG. 2,
). That is, the first solenoid valve 35 and the purge control valve 36 are maintained in the open state, while the second solenoid valve 39 is turned on and the drain shut valve 38 is closed to close the purge pipe 10.
Due to the suction force from the intake pipe 2 generated via the, the exhaust suppression system 11 is brought into a negative pressure state. In the figure, TR indicates the pressure reduction processing time.

Next, a leak down check is performed (shown in FIG. 2).

That is, when the discharge suppression system 11 becomes a predetermined negative pressure state, the purge control valve 36 is closed and the PT sensor 29
Check the change status of the tank pressure PT. When there is no leak from the emission suppression system 11, the change in the tank internal pressure PT hardly occurs as shown by the chain double-dashed line and the emission suppression system 1
While 1 is determined to be normal, when the evaporated fuel is leaking from the emission suppressing system 11, the tank internal pressure approaches the atmospheric pressure as shown by the solid line, so the fuel vapor leaks from the emission suppressing system 11, It is determined that the emission suppression system 11 has an abnormality. If the discharge suppression system 11 does not reach the predetermined negative pressure state within the predetermined time, the leak down check is not performed as described later.

After the abnormality determination is completed, the process proceeds to the normal purge (shown by FIG. 2).

That is, the second solenoid valve 39 is turned off while the first solenoid valve 35 is kept on, and the purge control valve 36 is opened so that normal purging is performed.
At this time, the tank internal pressure PT is open to the atmosphere and becomes substantially equal to the atmospheric pressure.

The abnormality diagnosis method for the emission control system 11 will be described in detail below with reference to the flowchart shown in the figure.

FIG. 3 is a flow chart showing a control procedure of the abnormality diagnosis processing of the emission suppressing system 11, and the ECU 5 (CPU) executes the control procedure.

First, in a step S1, a monitor permission judging routine, which will be described later, is executed. Then, in a step S2, whether or not the monitor for abnormality diagnosis is permitted, that is, the flag FMO
It is determined whether N is set to "1". When the answer is negative (NO), the first to third control valves 28, 36, 40 are set to the normal purge mode and the process ends, while when the answer is affirmative (YES), the atmosphere is released. The tank internal pressure at the time of opening is checked (step S3), and it is determined whether the check is completed (step S3).
4). When the answer is negative (NO), the process is ended as it is, while when the answer is affirmative (YES), that is, when the check of the tank internal pressure is completed, the first solenoid valve 35 is next. Is turned off to check the fluctuation of the tank internal pressure (step S5), and it is judged whether or not the check is completed (step S6). Then, when the answer is negative (NO), the processing is ended, while when the answer is affirmative (YES), the first to third control valves 28, 3 are provided.
Emission control system 1 including fuel tank 23 by operating 6, 40
1 is pressure-reduced (step S7).

On the other hand, at the same time when the pressure reducing process is started, the ECU
The first timer tmPRG built in 5 is started, and it is determined whether the timer value has passed a predetermined time T1 (step S8). Here, the predetermined time T1 is set to a time sufficient to bring the emission suppression system 11 into a predetermined negative pressure state in the normal state. Then, when the answer to step S8 is affirmative (YES), there is "perforation" or the like in the fuel tank 23 or the like, so that the discharge suppression system 11 cannot be set to a predetermined negative pressure state. Then, the process proceeds to step S12. On the other hand, when the answer to step S8 is negative (NO), it is determined whether or not the pressure reducing process is completed (step S9). And the answer is negative (N
If it is O), the processing is ended, but the answer is affirmative (YE
In the case of S), it is checked based on a leak down check routine to be described later whether or not fuel vapor has leaked from the emission suppression system 11 (step S10), and then it is determined whether or not the check is completed (step S10). Step S1
1).

If the answer is negative (NO), the process is terminated, while if the answer is affirmative (YES), the process proceeds to step S12.

In step S12, therefore, the system state of the emission control system 11 is determined, and then it is determined whether or not the determination process is completed (step S13). Then, when the answer is negative (NO), the processing is ended, while when the answer is affirmative (YES), the discharge suppressing system 11 is set to the normal purge mode (step S14) and the processing is ended.

Next, the above-mentioned processing steps will be sequentially described.

(1) Monitor permission judgment (step S in FIG. 3)
1) FIG. 4 is a flow chart of a monitor permission judgment routine for judging whether monitoring of abnormality diagnosis is permitted. This program is executed during background processing.

In step S21, it is determined whether the engine cooling water temperature TWI at the time of starting is lower than the predetermined temperature TWX. That is, the abnormality diagnosis of the present embodiment is sufficient to be executed when the engine is left unoperated for a long time (for example, once a day). First, when the IGSW is turned on, the engine cooling water temperature at the time of starting is first. The TWI is read and it is determined whether or not the engine cooling water temperature TWI is a predetermined temperature TWX, for example, 20 ° C. or lower.

When the answer is affirmative (YES), that is, when the engine cooling water temperature TWI at the time of starting is not higher than the predetermined temperature TWX, the current cooling water temperature TW detected by the TW sensor 15 is the predetermined lower limit value TWL (for example, 50 ° C.) and a predetermined upper limit value TWH (for example, 90 ° C.) are discriminated (step S22), and the answer is affirmative (YE
When S), the intake air temperature detected by the TA sensor 14 is equal to a predetermined lower limit value TAL (for example, 70 ° C.) and a predetermined upper limit value TA.
It is determined whether it is within the range of H (for example, 90 ° C.) (step S23). When the answer is affirmative (YES), it is determined that the engine is in the loose state, and the step S2 is performed.
Go to 4.

In step S24, the engine speed NE detected by the NE sensor 16 has a predetermined lower limit value NEL (eg, 2000 rpm) and a predetermined upper limit value NEH (eg, 40 rpm).
(00 rpm) is determined. When the answer is affirmative (YES), the PBA sensor 13
The absolute pressure PBA in the intake pipe detected by
It is determined whether or not it is within the range of BAL (for example, 350 mmHg) and the predetermined upper limit value PBAH (for example, -150 mmHg) (step S25). And the answer is affirmative (YES)
At this time, it is determined whether or not the throttle valve opening degree θTH detected by the θTH sensor 4 is within a range between a predetermined lower limit value θTH (for example, 1 °) and a predetermined upper limit value θTHH (for example, 5 °) (step S26). .. And the answer is affirmative (Y
When it is ES, it is determined whether the vehicle speed VSP detected by the VSP sensor 21 is in a range between a predetermined lower limit value VSPL (for example, 53 km / hr) and a predetermined upper limit value VSPH (for example, 61 km / hr) (step). S27). When the answer is affirmative (YES), the engine is in a slowdown,
Moreover, it is determined that the operating condition is stable, and the process proceeds to step S28.

In step S28, it is determined whether or not the vehicle is in a cruise traveling state. Whether or not the vehicle is in the cruise traveling state is determined by whether or not the vehicle speed variation within ± 0.8 km / sec continues for 2 seconds. Then, when the answer is affirmative (YES), it is determined whether or not purging has been performed for a certain period of time (step S2).
9). That is, when a large amount of vapor is stored in the canister 26, when the pressure of the emission control system 11 is decompressed to a predetermined negative pressure state, the decompression processing time increases due to the increase of the ventilation resistance, or during decompression processing. Thick vapor may be purged into the intake system. Therefore, in this embodiment, the fuel vapor adsorbed and stored in the canister 26 is reduced by performing purging for a certain period of time.

When the answer is affirmative (YES), the flag FMON is set to "1" to allow monitoring of abnormality diagnosis.
Is set (step S30), and this program ends. On the other hand, when at least one of the answers of the determination steps of S21 to S29 is negative (NO), the condition for permitting monitoring is not satisfied, so the flag FMON is set to "0" (step S31). This program ends.

(2) Tank internal pressure check when opening to the atmosphere (FIG. 3, step S3) FIG. 5 is a flowchart showing a tank internal pressure check routine when opening to the atmosphere. This program is executed during background processing.

First, in step S41, the emission control system 11
Is set to the tank internal pressure release mode, and the timer value of the second timer tmATMP is set to "0".
The timer tmATMP of is started. That is, the first electromagnetic valve 35 is turned on, the second electromagnetic valve 39 is turned off, the drain shut valve 38 is opened, and the purge control valve 36 is opened to reduce the tank internal pressure. Open to the atmosphere (see Figure 2).

Then, in step S42, it is determined whether or not the timer value of the second timer tmATMP has passed the predetermined time T2. Here, the predetermined time T2 is set to a time during which the internal pressure of the discharge suppression system 11 can be stabilized, for example, 4 seconds. Then, when the answer is negative (NO), the program is terminated, while when the answer is affirmative (YES), the process proceeds to step S43, and the PT sensor 29 measures the tank internal pressure PATM at the time of opening to the atmosphere. Then ECU5
Then, the check completion flag is set (step S44) and the program is terminated.

(3) Tank Internal Pressure Fluctuation Check (FIG. 3, Step S5) FIG. 6 is a flowchart showing a tank internal pressure fluctuation check routine. This program is executed during background processing.

First, in step S51, the emission control system 11
Is set to the tank pressure fluctuation check mode and the third
Timer tmTP is set to "0" to start the second timer tmTP. That is, the purge control valve 3
6 and the drain shut-off valve 38 are kept open, the first solenoid valve 35 is switched to the off state, and the discharge suppression system 1
1 to the tank pressure fluctuation check mode (Fig. 2,
reference).

Then, in step S52, it is determined whether or not the third timer tmTP has passed a predetermined time T3 (for example, 10 sec). When the answer is negative (NO), the program is terminated as it is, while when the answer is affirmative (YES), the tank pressure PCLS at the elapse of the predetermined time T3 is measured and stored in the ECU 5 (step S5
3), the first tank internal pressure change rate PV based on Equation (1)
The ARIA is calculated (step S54).

[0067]

[Equation 1] Then, the first tank internal pressure change rate PVARIA calculated as described above is stored in the ECU 5, a check end flag is set (step S55), and this program is ended.

(4) Tank internal pressure reduction processing (FIG. 3, step S7) FIG. 7 is a flowchart showing a tank internal pressure reduction processing routine. This program is executed during background processing.

First, in step S61, the emission control system 11
Is set to the tank internal pressure reduction processing mode (step S6).
1). That is, the purge control valve 36 is maintained in the open state, the first solenoid valve 35 is turned on, and the second solenoid valve is turned on to switch the drain shut valve 38 to the closed state (FIG. 2, ), The exhaust suppression system 11 is set to a predetermined negative pressure state by the suction force generated by the operation of the engine 1.
Next, it is determined whether or not the tank pressure PCHK at this time is equal to or higher than a predetermined negative pressure P1 (for example, -20 mmHg) (step S62). If the answer is negative (NO), the program is terminated, while the answer is affirmative (YE
When S) is reached, a processing end flag is set (step S63), and this program is ended.

(5) Leakdown Check (FIG. 3, Step S10) FIG. 8 is a flowchart showing a leakdown check routine, and this program is executed during background processing.

First, in step S71, the emission control system 11
To the leakdown check mode. That is,
The exhaust control system 11 and the intake pipe 2 of the engine 1 are shut off by closing the purge control valve 36 while maintaining the first solenoid valve 35 in the ON state and the drain shut valve 38 in the closed state (FIG. 2, see).

Next, in step S72, it is determined whether or not the tank internal pressure PST during the leak down check is measured. In the first loop, the answer to step S72 is negative (NO), so the routine proceeds to step S73, where the tank internal pressure PST is measured and the fourth timer tmLEAK is set to “0” and started.

Next, it is determined whether or not the fourth timer tmLEAK has passed a predetermined time T4 (for example, 10 seconds) (step S74). Then, in the first loop, the answer is negative (NO), so this program is terminated as it is.

On the other hand, in the next loop, the answer at step S72 is affirmative (YES), so the routine proceeds to step S74, where the fourth timer tmLEAK sets the predetermined time T.
It is determined whether 4 has passed. When the answer is negative (NO), the program is terminated as it is, while when the answer is affirmative (YES), the current tank internal pressure PEND for the leak down check is measured and stored in the ECU 5 ( In step S75), the second tank internal pressure change rate PVARIB is calculated based on equation (2) (step S76).

[0075]

[Equation 2] Then, the second tank internal pressure change rate PVARIB calculated as described above is stored in the ECU 5, a check end flag is set (step S77), and this program is ended.

(6) System State Determination Process (FIG. 3, Step S12) FIG. 9 is a flowchart showing an abnormality determination process routine, and this program is executed during background processing.

First, in step S81, it is determined whether or not the first timer tmPGR has passed the predetermined time T1 during the pressure reducing process. When the answer is affirmative (YES), it is determined that a large amount of fuel vapor has leaked from the emission suppression system 11 due to "piercing" of the fuel tank 23 or the like, and the routine proceeds to step S82, where the first Tank pressure change rate PVARI
It is determined whether A is larger than a predetermined value. When the answer is negative (NO), it means that the increase in the tank internal pressure at the time of checking the tank internal pressure fluctuation is low, and it is determined that a large amount of fuel vapor is leaking from the fuel tank 23, the pipe connection portion, or the like. An abnormality in the emission control system 11 is detected (step S83), and a processing end flag is set (step S86).
This program ends. Further, if the answer to step S82 is negative (NO), a large amount of fuel vapor is generated and the tank internal pressure rises (fluctuations) during the tank internal pressure variation check, so that the exhaust suppression system 11 is brought into a predetermined negative pressure state. In this case, the judgment is suspended (step S8).
4) A process end flag is set (step S86), and this program ends.

On the other hand, the answer to step S81 is negative (NO).
At this time, that is, when the discharge suppression system 11 can be brought to a predetermined negative pressure state, after executing a predetermined determination processing routine after completion of the depressurization processing (step S85), a processing completion flag is set (step S86). ) Exit this program.

The determination processing routine executed in step S85 is specifically executed according to the flowchart shown in FIG.

First, the second tank pressure change rate PVARI
It is determined whether the deviation between B and the first tank internal pressure change rate PVARIA is larger than a predetermined value P3.

That is, the tank pressure change rate PVARIB
Is caused by the leak from the emission control system 11,
Alternatively, in order to determine whether it is caused by the amount of steam generated in the fuel tank 23, the second tank internal pressure change rate PVARI
It is determined whether the deviation between B and the first tank internal pressure change rate PVARIA is larger than a predetermined value P3. That is, when the second tank internal pressure change rate PVARIB is large because the amount of steam generated in the fuel tank 23 is large, the answer to step S91 is negative (NO), and there is a large amount of leakage from the emission suppression system 11 to the outside. 2nd tank pressure change rate PVARI
If B is large, the answer to step S91 is affirmative (YES).
Becomes Here, the predetermined value P3 is set as shown in FIG. 11 according to the pressure reduction processing time TR. That is, the predetermined value P3
Is set to "P31" when the pressure reduction processing time TR is longer than the predetermined time TR1, and is set to "P32"(> P31) when the pressure reduction processing time TR1 is shorter than the predetermined time TR. Then, the answer in step S91 is affirmative (YE
S), that is, the second tank internal pressure change rate PVARIB
When the deviation between the first tank internal pressure change rate PVARIA and the first tank internal pressure change rate PVARIA is larger than the predetermined value P3, an abnormality in the emission suppression system 11 is detected (step S92), and the answer to step S91 is negative (N.
When it is O), it is judged that the emission suppression system 11 is normal (step S93), and the process is ended.

FIG. 12 is a flow chart showing another embodiment of the abnormality determination processing routine.

First, in step S101, the FV sensor 3
It is determined whether or not the fuel amount FV in the fuel tank 23 detected at 0 is equal to or larger than the first predetermined fuel amount FV1, that is, whether or not the fuel amount in the fuel tank 23 is equal to or larger than a predetermined fuel amount. To do. When the answer is affirmative (YES), the map [I] is selected, and when the answer is negative (NO), it is determined whether or not the fuel amount FV is equal to or more than the second predetermined fuel amount FV2, that is, for example, fuel. It is determined whether or not the fuel in the tank 23 is 1/2 or more of the full state (step S1).
03). Then, when the answer is affirmative (YES), the map [II] is selected (step S104), and when the answer is negative (NO), the map [III] is selected (step S105).

Next, in step S106, an abnormality determination is made based on each of the selected maps [I] to [III], and the process is terminated.

Specifically, the maps [I] to [III] are
As shown in FIG. 13, the first tank internal pressure change rate PVAR
It is divided into an abnormality determination region and a normal determination region based on the correlation between the IA and the second tank internal pressure change rate PVARIB, and it is determined by this map search whether or not the emission suppression system 11 is abnormal. (In the figure, the shaded area indicates the abnormality determination region.) (7) Normal Purge (FIG. 3, Step S14) FIG. 14 is a flowchart showing the setting conditions of each valve in the normal purge mode.

That is, the first solenoid valve 35 is turned on, and the drain shut valve 39 and the purge control valve 36 are opened to set the normal purge mode so that the engine 1 can suck air (step S111) This program ends.

[0087]

As described above in detail, according to the present invention, the fuel tank, the canister having the intake port, and the first fuel vapor passage connecting the canister and the fuel tank are provided. And a second control valve interposed in a purge passage that connects the canister and an intake system of the internal combustion engine to the internal combustion engine. The operating state detecting means for detecting the operating state of the fuel tank, the third control valve for opening and closing the intake port of the canister, the tank internal pressure detecting means for detecting the internal pressure of the fuel tank, and the first control valve. First variation amount detection means for controlling the opening / closing to detect the variation amount of the tank internal pressure, and controlling the first to third control valves when the operation of the engine is detected by the operation state detection means. The above Decompression processing means for bringing the generated fuel discharge inhibiting system into a predetermined negative pressure state, and closing the second control valve to detect the fluctuation amount of the internal pressure of the evaporated fuel discharge inhibiting system from the negative pressure state. And an abnormality determination processing system for determining abnormality of the evaporated fuel emission suppression system based on the detection results of the first and second variation amount detection means. Therefore, the fluctuation amount of the tank internal pressure can be detected before the depressurization process is performed, and the evaporative emission control system is based on the fluctuation amount (steam generation amount) and the fluctuation amount of the tank internal pressure after the depressurization process. Abnormalities are determined.

Further, since the determination value for determining the abnormality of the evaporated fuel discharge inhibiting system by the abnormality determining means is determined according to the pressure reducing processing time in the pressure reducing processing means, the abnormality determination of the fuel evaporation inhibiting system is performed. Is appropriately performed according to the pressure reduction processing time.

Further, an operating state detecting means for detecting an operating state of the engine, a third control valve for opening / closing the intake port of the canister, a tank internal pressure detecting means for detecting an internal pressure of the fuel tank, First variation amount detection means for detecting the variation amount of the tank internal pressure by controlling the opening / closing of the first control valve, and the first to third characteristics when the operation of the engine is detected by the operation state detection means. A pressure reducing means for controlling the control valve to bring the vaporized fuel emission restraining system into a predetermined negative pressure state; and a second control valve being closed to bring the vaporized fuel emission restraining system from the negative pressure state. Second fluctuation amount detecting means for detecting a fluctuation amount of the internal pressure, fuel amount detecting means for detecting a fuel amount in the fuel tank, and the first and second
In the case where an abnormality determination processing system including an abnormality determination processing unit configured to determine the abnormality of the evaporated fuel emission suppression system based on the detection result of the fluctuation amount detection unit and the fuel amount detection unit The abnormality of the evaporative fuel discharge system is determined based on the fuel amount, the steam generation amount, and the pressure fluctuation amount after the pressure reduction process.

Further, according to the present invention, since the processing time purge is performed before the processing by the abnormality determination processing system is started, the fuel vapor adsorbed and stored in the canister is reduced and the depressurization processing time is extremely increased. It is possible to prevent the rich vapor from being purged into the intake system.

As described above, according to the present invention, even if a large amount of fuel vapor is generated in the fuel tank, the pressure fluctuation amount after the depressurization process is corrected by the fuel amount and the vapor generation amount in the tank. It is possible to detect an abnormality of the system with high accuracy and accuracy.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an evaporated fuel processing apparatus for an internal combustion engine according to the present invention.

FIG. 2 is a diagram showing operation patterns of first and second solenoid valves, a drain shut valve, and a purge control valve.

FIG. 3 is a flowchart showing a main routine of the present invention.

FIG. 4 is a flowchart of a monitor permission determination routine.

FIG. 5 is a flow chart of a tank internal pressure check routine when opening to the atmosphere.

FIG. 6 is a flowchart of a tank internal pressure fluctuation check routine.

FIG. 7 is a flowchart of a tank internal pressure reduction processing routine.

FIG. 8 is a flowchart of a leak down check routine.

FIG. 9 is a flowchart of a system state determination processing routine.

FIG. 10 is a flowchart of an abnormality determination processing routine.

FIG. 11 is an abnormality determination value map diagram.

FIG. 12 is a flowchart showing another embodiment of an abnormality determination processing routine.

FIG. 13 is another example of the abnormality determination value map diagram.

FIG. 14 is a flowchart showing a procedure for setting a normal purge.

[Explanation of symbols]

1 Internal Combustion Engine 5 ECU (Decompression Processing Means, Abnormality Judgment Means, Variation Amount Detection Means, Steam Generation Amount Detection Means) 10 Purge Passage 11 Evaporative Emission Control System 21 IGSW Sensor (Operating State Detection Means) 23 Fuel Tank 25 Intake Port 26 Canister 27 Fuel vapor flow passage 28 First control valve 29 PA sensor (tank internal pressure detection means) 30 FV sensor (fuel amount detection means) 36 Purge control valve (second control valve) 40 Third control valve

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[Procedure amendment]

[Submission date] January 28, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

[0005]

However, in the abnormality determining method in the above-described evaporative fuel treatment apparatus, the fuel vapor leaks due to the fluctuation of the internal pressure after the evaporative fuel discharge inhibiting system is brought to a predetermined negative pressure state. detects whether dolphins not, because a abnormality determination system, when a large amount of fuel vapor in the fuel tank is occurring, pressure fluctuations during the leak down check is increased, the system is normal Nevertheless, a new problem has arisen that abnormalities are detected.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0057

[Correction method] Change

[Correction content]

When the answer is affirmative (YES), that is, when the engine cooling water temperature TWI at the time of starting is not higher than the predetermined temperature TWX, the current cooling water temperature TW detected by the TW sensor 15 is the predetermined lower limit value TWL (for example, 50 ° C.) and a predetermined upper limit value TWH (for example, 90 ° C.) are discriminated (step S22), and the answer is affirmative (YE
When S), the intake air temperature detected by the TA sensor 14 is equal to a predetermined lower limit value TAL (for example, 70 ° C.) and a predetermined upper limit value TA.
It is determined whether it is within the range of H (for example, 90 ° C.) (step S23). Then, if the answer is affirmative (YES), it is determined that the engine is in a warm-up state, and step S2 is performed.
Go to 4.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0058

[Correction method] Change

[Correction content]

In step S24, the engine speed NE detected by the NE sensor 16 has a predetermined lower limit value NEL (eg, 2000 rpm) and a predetermined upper limit value NEH (eg, 40 rpm).
(00 rpm) is determined. When the answer is affirmative (YES), the PBA sensor 13
The absolute pressure PBA in the intake pipe detected by
It is determined whether or not it is within the range of BAL (for example, 350 mmHg) and the predetermined upper limit value PBAH (for example, -150 mmHg) (step S25). And the answer is affirmative (YES)
At this time, it is determined whether or not the throttle valve opening degree θTH detected by the θTH sensor 4 is within a range between a predetermined lower limit value θTH (for example, 1 °) and a predetermined upper limit value θTHH (for example, 5 °) (step S26). .. And the answer is affirmative (Y
When it is ES, it is determined whether the vehicle speed VSP detected by the VSP sensor 21 is in a range between a predetermined lower limit value VSPL (for example, 53 km / hr) and a predetermined upper limit value VSPH (for example, 61 km / hr) (step). S27). If the answer is affirmative (YES), the engine is warming up ,
Moreover, it is determined that the operating condition is stable, and the process proceeds to step S28.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0067

[Correction method] Change

[Correction content]

[0067]

[Equation 1] Then, the first tank internal pressure change rate PVARIA calculated as described above is stored in the ECU 5, a check end flag is set (step S55), and this program is ended.

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

[Procedure correction 6]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

[Procedure Amendment 7]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

[Procedure Amendment 8]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 14

[Correction method] Change

[Correction content]

FIG. 14

Continued Front Page (72) Inventor Hiroshi Maruyama 1-4-1 Chuo, Wako-shi, Saitama Stock Research Institute Honda Technical Research Institute

Claims (5)

[Claims] 1. A fuel tank, a canister having an intake port, a first control valve interposed in a fuel vapor flow passage connecting the canister and the fuel tank, the canister and an internal combustion engine. In an evaporative fuel treatment apparatus for an internal combustion engine having an evaporative emission control system including a second control valve interposed in a purge passage connecting with an intake system, an operating state detecting means for detecting an operating state of the engine, A third control valve for opening and closing the intake port of the canister,
The tank internal pressure detecting means for detecting the internal pressure of the fuel tank, the first variation amount detecting means for detecting the variation amount of the tank internal pressure by controlling the opening and closing of the first control valve, and the engine by the operating state detecting means. Pressure reducing means for controlling the first to third control valves to bring the evaporative emission control system into a predetermined negative pressure state when the operation is detected,
Second variation amount detection means for detecting the variation amount of the internal pressure from the negative pressure state of the evaporative emission control system by closing the control valve of the above-mentioned control valve, and the first and second variation amount detection means. An evaporative fuel treatment system for an internal combustion engine, comprising: an abnormality determination processing system including abnormality determination means for determining an abnormality of the evaporative emission control system on the basis of the detection result. 2. The discriminant value for determining the abnormality of the evaporative emission control system by the abnormality determining means is determined according to the pressure reducing processing time in the pressure reducing processing means. Evaporative fuel treatment system for internal combustion engine. 3. A fuel tank, a canister provided with an intake port, a first control valve interposed in a fuel vapor flow passage connecting the canister and the fuel tank, the canister and an internal combustion engine. In an evaporative fuel treatment apparatus for an internal combustion engine having an evaporative emission control system including a second control valve interposed in a purge passage connecting with an intake system, an operating state detecting means for detecting an operating state of the engine, A third control valve for opening and closing the intake port of the canister,
The tank internal pressure detecting means for detecting the internal pressure of the fuel tank, the first variation amount detecting means for detecting the variation amount of the tank internal pressure by controlling the opening and closing of the first control valve, and the engine by the operating state detecting means. Pressure reducing means for controlling the first to third control valves to bring the evaporative emission control system into a predetermined negative pressure state when the operation is detected,
Second variation amount detecting means for detecting the variation amount of the internal pressure of the evaporated fuel discharge system from the negative pressure state by closing the control valve of No. 3, and the fuel amount for detecting the fuel amount in the fuel tank. An abnormality determination processing system including a detection unit, and an abnormality determination unit configured to determine an abnormality of the evaporated fuel emission suppression system based on the detection results of the first and second fluctuation amount detection units and the fuel amount detection unit. An evaporative fuel treatment system for an internal combustion engine, comprising: 4. The first variation amount detecting means is the first variation amount detecting means.
4. The evaporated fuel processing apparatus for an internal combustion engine according to claim 1, wherein the control valve is controlled to be opened and closed to detect the amount of fluctuation of the tank internal pressure. 5. The purging is performed for a predetermined time before the processing by the abnormality determination processing system is started.
An evaporated fuel processing apparatus for an internal combustion engine according to claim 4.