JPH02130256A - Self diagnosing device of evaporated fuel gas diffusion preventing device - Google Patents

Abstract

PURPOSE:To surely diagnose the device by opening and closing a discharge passage by controlling an opening/closing means when a prescribed time lapses after the supply of oil into a fuel tank is detected and by judging the existence of anomaly from the variation of the air-fuel ratio at that time. CONSTITUTION:The supply of oil into a fuel tank 7 is detected by a fuel level sensor 11, and when a prescribed time lapses after the detection of the supply of oil into the tank 7, it is judged that a sufficient quantity of evaporated fuel gas is adsorbed onto the activated charcoal in a canister 14, and a discharge passage 13a is opened and closed by controlling a purge valve 15, and the existence of anomaly is judged from the fact that the difference of the air-fuel ratio detected by an O2 sensor 6 is within a prescribed value or not. When anomaly is judged, an alarm lamp 17 comes ON. Therefore, when the low boiling point component of fuel are evaporated and adsorbed onto the activated charcoal of the canister 14, the canister 14 and a suction pipe 2 are allowed to communicate, and the erroneous judgement is prevented, and the evaporated fuel gas diffusion preventing device is surely diagnosed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a self-diagnosis device for a fuel evaporative gas diffusion prevention device.

[Prior Art] In recent years, many failure detection devices for devices such as sensors and actuators used in engine control systems have been proposed and put into practical use. However, regarding the fuel evaporative gas diffusion prevention device, the evaporative gas purge control device was developed in Japanese Patent Laid-Open No. 57-5
No. 2663, Japanese Unexamined Patent Publication No. 57-129247, etc., have proposed such methods, but there is no failure detection device yet. In order to check the operation of the fuel evaporative gas diffusion prevention device, if the canister containing activated carbon that adsorbs fuel evaporative gas is communicated with the intake system downstream of the throttle valve, evaporative gas will flow into the intake pipe. It is better to detect that it has been purged.

[Problem to be Solved by the Invention] However, when checking the operation of the fuel evaporative gas diffusion prevention device, it is found that the canister and the intake pipe are not connected to each other because evaporative gas is not generated from fuel whose low boiling point components have completely evaporated. However, the fuel evaporative gas may not be purged, and there is a risk of misjudgment.

That is, instead of determining that the fuel evaporative gas is not purged, it is determined that an abnormality has occurred in the fuel evaporative gas diffusion prevention device.

An object of the present invention is to provide a self-diagnosis device that can reliably diagnose a fuel evaporative gas diffusion prevention device while preventing erroneous determinations.

[Means for Solving the Problems] The present invention provides a canister that communicates with a fuel tank and houses activated carbon that adsorbs fuel evaporation gas from the fuel tank;
a discharge passage communicating the canister with an intake passage of the internal combustion engine; an opening/closing means provided in the discharge passage for opening and closing the discharge passage; and an air-fuel ratio detection means for detecting the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine. a refueling detection means for detecting refueling to the fuel tank; and a refueling detection means for controlling the opening and closing means to open and close the discharge passage when a predetermined time has elapsed after the refueling detection means detects refueling to the fuel tank. A fuel evaporative gas diffusion device comprising: a determining means for determining the presence or absence of an abnormality based on a change in the air-fuel ratio by the air-fuel ratio detecting means; and a warning means for issuing a warning when the determining means determines that there is an abnormality. The gist is a self-diagnosis device for a prevention device.

[Operation] When a predetermined period of time has elapsed after the refueling detection means detects refueling in the fuel tank, the determination means determines that the fuel vapor gas has been sufficiently adsorbed by the activated carbon of the canister, and controls the opening/closing means to open the discharge passage. The opening and closing operations are performed, and the presence or absence of an abnormality is determined based on the change in the air-fuel ratio by the air-fuel ratio detection means at that time. The warning means issues a warning when the determining means determines that there is an abnormality.

[Example] An example embodying the present invention will be described below with reference to the drawings.

The vehicle is equipped with a multi-cylinder engine 1 as an internal combustion engine shown in FIG.
and the exhaust pipe 3 are connected. An electromagnetic fuel injection valve 4 is provided in each cylinder intake part of the intake pipe 2, and
A throttle valve 5 is provided in the intake pipe 2 . Roughly speaking, the exhaust pipe 3 has 021? as an air-fuel ratio detection means. A sensor 6 is provided, and the sensor 6 outputs a voltage signal according to the oxygen concentration in the exhaust gas.

The fuel supply system that supplies fuel to the fuel injection valves 4 includes a fuel pump 8 that pumps fuel from a fuel tank 7 to each injection valve 4 via a fuel filter 9, and a pressure regulating valve 10.
The fuel supplied to each injection valve 4 is adjusted to a predetermined pressure. The fuel tank 7 is provided with a float type fuel level sensor 11 as a fuel supply detection means. This Renly 11 detects the amount of fuel by detecting the level of a float 11a provided in the tank 7 using a potentiometer 11b.

The ceiling of the fuel tank 7 and the surge tank 12 of the intake system
and is communicated with through a purge pipe 13, and a canister 14 containing activated carbon is disposed in the middle of the purge pipe 13. Then, the fuel evaporative gas in the fuel tank 7 is adsorbed by the activated carbon in the canister 14. The purge pipe 13 has a discharge passage 13a on the side closer to the surge tank 12 than the canister 14, and a purge electromagnetic valve (hereinafter referred to as a purge valve) 15 is provided in the middle of the discharge passage 13a.

This verge valve 15 is normally biased by a spring (path shown) in a direction in which the valve body 15a opens the seat portion 15b, but by energizing the coil 15c, the valve body 15a closes the seats 1 to 15b. It looks like this. Therefore, demagnetization of the purge valve 15 opens the discharge passage 13a, and excitation of the purge valve 15 closes the discharge passage 13a.

A control circuit 16 as a determination means having a built-in microcomputer receives a throttle opening signal from a throttle sensor 1 (the path shown) that detects the opening of the throttle valve 5, and a rotation speed sensor that detects the rotation speed of the engine 1. The engine speed signal from the intake air amount sensor (shown path) that detects the intake air amount, and the intake air amount signal from the water temperature sensor +j (shown path) that detects the temperature of the engine cooling water. The cooling water temperature signal and the intake air mixture signal q from the intake air temperature sensor (shown in the figure) that detects the intake air temperature are input.Then, the control circuit 16 determines the opening degree of the throttle valve 5 from these signals.
Detects engine speed, intake air volume, engine coolant temperature, and intake air temperature.

Moreover, the control circuit 16 is operated by the 02t? The signal from the fuel tank 6 is input to determine whether the air-fuel mixture is rich or lean. and,
The control circuit 16 changes (skips) the feedback correction coefficient FAF stepwise as shown in FIG. 6 in order to increase or decrease the fuel injection amount when the change is from rich to lean or from lean to rich. Alternatively, when the engine is lean, the feedback correction coefficient FAF is gradually increased or decreased. Further, the control circuit 16 determines the basic injection interval 04 based on the engine speed and the intake air amount, corrects the basic injection time using a feedback correction coefficient FAF, etc. to determine the final injection time, and determines the predetermined injection timing by the fuel injection valve 4. to perform fuel injection.

The control circuit 16 also receives a signal from the fuel level sensor 1/11. In general, the control circuit 16 is connected to the purge valve 15 and controls opening and closing of the purge valve 15. Further, a warning lamp 17 as a warning means is provided on the instrument panel of the vehicle and is connected to a control circuit 16.

Next, the operation of the control circuit 16 configured as described above will be explained.

2, 3, and 4 show flowcharts for explaining the operation, and flags Fl, F2, . The operation timings of the flag F3 and the counters C1, C2, and C3 are shown in FIGS. 5 and 6. The counter C1 measures the time h after refueling, and the counter C2 measures the time when the purge valve 15 is opened for self-diagnosis when a predetermined time t1 has elapsed after refueling.
3 takes the time when the purge valve 15 is closed for self-diagnosis. Also, the flag F1 indicates that the fuel in the fuel tank 7 is 201
(litre) or less, it becomes “0” and 50
．． As soon as it becomes 0 or more, it becomes 11. The flag F2 remains "1" from the predetermined time t1 after refueling until the counter C3's run 1 to the 1st shift reaches N33, and the flag F3 remains "1" until the counter C2's run 1 to the 1st shift reaches N22, and then the counter C3's run I starts. ~(It becomes "1" until the direct reaches N33.

First, based on FIG. 2 and FIG. 5, the detection of the refueling operation to the fuel tank 7 and the detection of the predetermined time t1 after refueling will be explained.

The control circuit 16 controls the fuel level sensor 11 in step 100.
It is determined whether the amount of fuel in the fuel tank 7 is 20g (liter) or more, and if it is less than 20p, step 101,
At 102, flag F1=O and counter C1 count (
Set direct to “O”. Roughly speaking, the control circuit 16 performs step 1.
At step 03, it is determined whether the flag F1=1.

When the amount of fuel in the fuel tank 7 exceeds 201, the control circuit 16 determines that the amount of fuel in the fuel tank 7 is 5O in step 104.
If the fuel amount exceeds 50fl, it is determined in step 105 whether flag F1=O or not, and if flag F1=0, in step 106 flag F1=0 is determined.
Set 1.

Then, in step 103, the control circuit 16 sets the flag F1=
If it is 1, the counting operation of the force 1 counter C1 is started in step 107. The control circuit 16 performs step 10
At step B, the count of the counter C1 is compared with a predetermined value N2, and if the count value is less than N2, it is compared with a predetermined value Nl (<N2) in step 109.

When the count value of the counter C1 exceeds the predetermined value N1 in step 109, the control circuit 16 sets the flag F2=1 in step 110. The time when the count value of the counter C1 exceeds the predetermined value N1 is when the predetermined time t1 has elapsed after refueling. More specifically, this predetermined time t1 is 1 to 5 hours. Further, the control circuit 16 determines in step 108 that the count value of the counter C1 is a predetermined value N2.
If the value exceeds 1, the counter C1's number 1~
Set the value to N2. That is, this step 111 provides a limiter function so that the value of the counter C1 does not exceed N2.

Next, regarding the control operation of the purge valve 15, FIGS.
This will be explained based on the diagram.

Control circuit 16 determines in step 200 whether operating conditions are met. This means that the opening degree of the throttle valve 5 is 5°.
and 40 degrees, and the engine speed is 110
If it is 0 Orp or more, it is determined that the operating conditions have been met. If the operating conditions are not satisfied, the control circuit 16 turns off (closes) the purge valve 15 in step 201, and sets the count of the counter C2 (direct to "O", counter C3
The count value of is set to rOJ.

When the operating condition is established in step 200, the control circuit 16 determines whether the flag F2-1 is set in step 202, and if the flag F2 is not set to 1, the control circuit 16 performs step 2.
At 03, the purge valve 15 is turned on (opened), and the counter C2's run 1-1 direct is set to "O", and the counter C3's run 1 (direct is set to rOJ).

If the flag F2 is set to 1 in step 202, that is, if the predetermined time t1 after refueling has elapsed, the control circuit 16 determines whether the engine is in steady operation and under air-fuel ratio feedback control in step 204. to judge. The judgment that this engine is in steady operation is that the opening of the throttle valve 5 is not operated suddenly and the opening speed of the throttle valves 1 to 2 is 2°.
/second or less.

If the condition of step 204 is satisfied, the control circuit 16 determines whether the flag "3=O" is set in step 205, and if the flag F3=0, turns on (opens) the purge valve 15 in step 206. At the same time, in step 207, the count 1 of the counter C2 + 1 is set as the new count 1 of the counter C2.The control circuit 16 determines in step 208 whether or not the count value of the count C2 has reached a predetermined value N22. Then, when it becomes N22, step 209
The feedback correction coefficient FAF@FAF1 at that time is
In step 210, the count value of the counter C3 is set to O and the flag F3 is set to 1.

Through the processing of steps 206 to 210, as shown in FIG. 6, when the count value of the counter C2 after the purge valve 15 is opened reaches N22 (time t2 = several seconds), the feedback correction coefficient FAF is set as FAFl. Ru.

Here, the feedback correction coefficient FAF is updated by 63FAF+FAF AF- in step 300, which is executed every predetermined time, as shown in FIG.

Further, the control circuit 16 sets the flag F3- in step 205.
1, the purge valve 15 is turned off (closed) in step 211, and in step 212, the count 1 to (direct+1) of the counter C3 is set as the count 1 of the new counter C3.The control circuit 16 turns off the purge valve 15 in step 211. It is determined whether or not the count value reaches a predetermined value of N33, and when the count value reaches N33, the feedback correction coefficient FAF at that time is changed to F in step 214.
AF2 is set, and in step 215, the count value of counter C2 = O, flag F2 = 0. Set flag F3=O.

In the processing of steps 211 to 215, as shown in FIG. 6, after the purge valve 15 is opened, the counter C3 value becomes N33 (feedback correction coefficient 11) (time t3 = several seconds). T A F @ F A F2
Set to .

Roughly, in step 216, the control circuit 16 calculates the FAFl obtained in steps 209 and 214.

The difference in FAF2 (=FAF2-FΔF1) is determined, and it is determined whether the difference is larger than a predetermined value α. If it is smaller, it is determined that there is an abnormality and the warning lamp 17 is turned on to notify the occupant.

That is, if the device is functioning normally, by opening the barge valve 15, the fuel vapor adsorbed by the activated carbon in the canister 14 is supplied into the intake pipe 2, and the air-fuel ratio becomes rich. By closing the purge valve 15, the air-fuel ratio becomes lean, and in step 216 F
There is a difference between AFI and FAF2 that is larger than the predetermined value α. However, in step 216, the fact that FΔ[1 and FAF2 cannot have a difference larger than the predetermined value α means that the purge pipe 1
3. It is determined that there is an abnormality such as clogging.

As described above, according to the self-diagnosis device of this embodiment, the fuel level sensor 11 detects the refueling of the fuel tank 7, and when the predetermined time t1 has elapsed after the refueling of the fuel tank 7 is detected, the fuel evaporation is detected. When it is determined that the gas has been sufficiently adsorbed by the activated carbon in the canister 14, the barge valve 15 is controlled to open and close the discharge passage 13a, and the air-fuel ratio (feedback correction coefficient FAF1.F) determined by the 02 sensor 6 at that time is
The presence or absence of an abnormality is determined based on whether the difference in AF2> is greater than or equal to a predetermined value (α) or less than a predetermined value (α), and when it is determined that an abnormality exists, a warning lamp 17 is turned on to issue a warning. Therefore, when determining whether or not there is an abnormality in the fuel evaporative gas diffusion prevention device, when the low boiling point components of the fuel evaporate and are adsorbed by the activated carbon in the canister 14, the canister 14 and the intake pipe 2 are communicated with each other, resulting in an erroneous determination. This allows the fuel evaporative gas diffusion prevention device to be reliably diagnosed.

It should be noted that the present invention is not limited to the above-mentioned embodiment. For example, as shown in FIG. , it may also be possible to perform self-diagnosis when this condition (1) is also satisfied.

[Effects of the Invention] As described in detail above, the present invention provides an excellent effect of preventing erroneous judgments and reliably diagnosing the fuel evaporative gas diffusion prevention device.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration around the engine of the embodiment, Fig. 2 is a flowchart 1 for explaining the operation of the embodiment, Fig. 3 is a flowchart for explaining the operation of the embodiment,
FIG. 4 is a flowchart 1 for explaining the operation of the embodiment.
~, Fig. 5 is a time chart showing various processes associated with changes in fuel amount, Fig. 6 is a time chart showing various processes associated with self-diagnosis operations, and Fig. 7 is for explaining the effects of separate embodiments. This is a flowchart. 2 is an intake pipe, 6 is an air-fuel ratio detection means (NO), 7 is a fuel tank, 11 is a fuel level sensor as a refueling detection means, 13a is a discharge passage, 14 is a canister,
15 is a purge valve as an opening/closing means, 16 is a control circuit as a determining means, and 17 is a warning lamp as a warning means. Patent applicant Nippondenso Co., Ltd. Agent
Patent Attorney On 1) Hiroki Refueling ↓

Claims (1)

[Claims] 1. A canister that communicates with a fuel tank and stores activated carbon that adsorbs fuel vapor from the fuel tank; a discharge passage that communicates the canister with an intake passage of an internal combustion engine; and the discharge passage. an opening/closing means provided therein for opening and closing the discharge passage; an air-fuel ratio detection means for detecting the air-fuel ratio of the air-fuel mixture to the internal combustion engine; a refueling detection means for detecting refueling to the fuel tank; and the refueling detection When a predetermined period of time has elapsed after the detection of refueling of the fuel tank by the means, the opening/closing means is controlled to open and close the discharge passage, and the change in the air-fuel ratio detected by the air-fuel ratio detecting means at that time detects an abnormality. A self-diagnosis device for a fuel evaporative gas diffusion prevention device, comprising a determining means for determining the presence or absence of an abnormality, and a warning means for issuing a warning when the determining means determines that there is an abnormality. 2. The determining operation of the determining means is to determine the presence or absence of an abnormality based on whether the difference in air-fuel ratio detected by the air-fuel ratio detecting means when the discharge passage is opened and closed is greater than or equal to a predetermined value or less than a predetermined value. Self-diagnosis device for fuel evaporative gas diffusion prevention device.