JPH02136558A - Self diagnosing device in evaporated fuel gas diffusion preventing device - Google Patents

Abstract

PURPOSE:To self-diagnose the correctness of operation by opening and closing a discharge passage for the communication between a canister and a suction passage when the pressure in a fuel tank is over a prescribed value and judging anomaly on the basis of the variation of the air-fuel ratio and generating alarm. CONSTITUTION:A fuel tank 7 and a surge tank 12 communicate each other through a purge pipe 13, and a canister 14 is arranged in the purge pipe 13. As for the purge pipe 13, the surge tank 12 side in comparison with the canister 14 is set in a discharge passage 13a, and a purge valve 15 is arranged in the discharge passage 13a. The purge valve 15 is opened and closed by a control circuit 16, on the basis of each detection signal of an air-fuel ratio sensor 6 installed in the exhaust pipe 3 and a pressure sensor 11 installed onto a fuel tank 7. Further, in the control circuit 16, the existence of anomaly is judged by the variation of the air-fuel ratio, and if the existence of anomaly is judged, an alarm means 17 is operated.

Description

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

[Prior art] Fuel vapor diffusion prevention devices have been widely known in the past, which guide volatile fuel (fuel evaporative gas) in a fuel tank to a canister, adsorb it to activated carbon in a canister, and roughly guide it to an intake pipe where it is combusted. It is being Further, in this fuel evaporative gas diffusion prevention device, a method for controlling the amount of fuel introduced from the starter to the intake pipe is disclosed in, for example, Japanese Patent Laid-Open No. 63-85237.

[Problems to be Solved by the Invention] However, these devices cannot detect whether the fuel has been properly inhaled and combusted. There is a risk that the pressure inside the fuel tank will become abnormally high or that a large amount of fuel may evaporate into the atmosphere through the safety valve installed in the canister.

An object of the present invention is to provide a self-diagnosis device capable of determining abnormality of a fuel evaporative gas diffusion prevention device and detecting whether fuel evaporative gas is properly inhaled and combusted.

[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. and an in-tank pressure detection means for detecting the in-tank pressure in the fuel tank, and when the in-tank pressure detected by the in-tank pressure detection means is equal to or higher than a predetermined pressure,
a determining means for controlling the opening/closing means to open and close the discharge passage, and determining the presence or absence of an abnormality based on a change in the air-fuel ratio by the air-fuel ratio detecting means at that time; and determining that there is an abnormality by the determining means. The gist of this is a self-diagnosis device in the Fuel Evaporative Gas Diffusion Prevention 'IA@, which is equipped with a warning means that warns when a problem occurs.

[Operation] The determining means controls the opening/closing means to open and close the discharge passage when the internal pressure in the fuel tank determined by the tank internal pressure detecting means is equal to or higher than a predetermined pressure, and the air-fuel ratio detecting means at that time opens and closes the discharge passage. The presence or absence of an abnormality is determined based on changes in the air-fuel ratio. When the determining means determines that there is an abnormality, the warning means issues a warning.

[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 as 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
The intake pipe 2 is provided with throat valves 1 to 5. moreover,
The exhaust pipe 3 has 02't? as an air-fuel ratio detection means. Nri 6
The sensor 6 outputs a voltage corresponding 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. A pressure 7J sensor 11 is provided on the ceiling surface of the fuel tank 7 as means for detecting pressure inside the tank. This pressure sensor 11 detects the evaporation pressure of the fuel in the tank 7.

The ceiling of the fuel tank 7 and the 4-noge tank 1 of the intake system
2 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. Further, the canister 14 is provided with a safety valve 1B, and when the fuel evaporative gas reaches a predetermined pressure or higher, the safety valve 1B opens and the fuel evaporative gas is discharged.

The purge pipe 13 is larger than the large tank 12 than the KiP nister 14.
The side thereof is a discharge passage 13a, and a purge electromagnetic valve (hereinafter referred to as a purge valve) 15 is provided in the middle of this discharge passage 13a.

This purge valve 15 is normally biased by a spring (not shown) in a direction in which the valve body 15a listens to the seats 1 to 15b, but by energizing the coil 15c, the valve body 15a closes the seat part 15b. It looks like this. Therefore, the discharge passage 13a is opened by the magnetization of the purge valve 15, and the discharge passage 13a is closed by the excitation of the purge valve 15.

A control circuit 16 as a determination means having a built-in microcomputer receives a throttle signal from a throttle sensor (not shown) that detects the opening degree of the throttle valve 5 and a rotation speed that detects the rotation speed of the engine 1. An engine rotation speed signal from a sensor (not shown), an intake air amount signal from an intake air amount sensor (not shown) that detects the intake air level, and a water temperature sensor (not shown) that detects the temperature of engine cooling water. The intake temperature sensor (which detects the cooling water temperature signal from the
(not shown) is input. From these signals, the control circuit 16 detects the opening degrees of the throttle valves 1 to 5, engine speed, intake air amount, engine cooling water temperature, and intake air temperature.

Also, the fl,+ control circuit 16 is connected to the 02't? The signal from the connector 6 is input (see Fig. 2). Further, the control circuit 16 determines the basic distance between the injection ports 4 based on the engine speed and the intake air temperature,
The basic injection time is corrected using a feedback correction coefficient FAF, etc. to obtain the final injection time, and the fuel injection valve 4
This causes fuel injection to be performed at a predetermined injection timing.

The control circuit 16 also receives a signal from the pressure sensor 11. Further, a 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 vehicle's input panel and is connected to a control circuit 16.

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

First, the feedback control of the air-fuel ratio will be explained based on FIG. 3. As shown in FIG.
The output voltage of sensor 'v6 and comparison voltage Vref are compared to determine whether the air-fuel mixture is rich or 1-nor. Then, in step 100, the control circuit 16 determines 11fi whether the conditions for feedback control are satisfied. It is determined that the conditions are met when the engine water temperature is 40°C or higher and the throttle opening is 70' or lower. If the condition is not satisfied, the control circuit 16 sets the feedback correction coefficient FΔF=1.0 in step 101.

Then, the control circuit 16 outputs 02't? Based on the signal from the engine 6, it is determined in step 102 whether the air-fuel ratio is rich or not, and if it is rich, it is compared with the previous detection result in step 103 to determine whether the ratio has changed from lean to rich. When the control circuit 16 is inverted from low to rich, the feedback correction coefficient FAF-α (α
skip m) to new feedback correction coefficient FΔF
At the same time, if there is no reversal from lean to rich, in step 105, the feedback correction coefficient FΔF-β (β is the integral amount, α)β) is changed to a new feedback correction coefficient FA.
Let it be h.

Further, in step 102, if the control circuit 16 is lean, the control circuit 16 compares it with the previous detection result in step 106 to determine whether or not there has been a reversal from rich to lean. When the control circuit 16 reverses from rich to lean, step 10
Step 7 sets the feedback correction coefficient FAF ten α (α is the skip maximum) as a new feedback correction coefficient FAF, and if there is no reversal from rich to lean, step 108
The feedback correction coefficient FΔF+β (β is the integral amount) is set as a new feedback correction coefficient FAF.

Therefore, if there is a reversal between rich and lean in the processing of steps 102 to 108, the feedback correction coefficient FAF is changed in a stepwise manner (skip) to increase or decrease the fuel injection amount, and when the fuel injection amount is rich or lean, the feedback correction coefficient FAF is avoided. Gradually increase or decrease the coefficient FAF.

Further, the control circuit 16 is connected to step 109C pressure bottle +111.
It is determined whether the internal pressure in the fuel tank 7 is higher than a predetermined pressure and the purge valve 15 is opened. Then, if the condition is not satisfied, the control circuit 16 controls the feedback correction coefficient F in step 110.
The AF is guarded so that it falls within the range of 0.8≦FAF≦1.2, and when the conditions in step 109 are met, the air-fuel ratio becomes rich during purge, so the lower limit value is set in skip 111. Change the feedback correction coefficient FA
Guard so that F falls within the range of 0.7≦F∆F≦1.2.

As shown in FIG. 4, the control circuit 16 performs step 3 in step 200 when the time set by the built-in timer is 0 to 4 seconds.
The abnormality determination routine is executed at step 00, and when the timer is 4 to 30 seconds, the purge valve 15 is opened at step 400, and the canister 14 and the intake system of the engine 1 are brought into communication. That is, the abnormality determination routine is executed for 0 to 4 seconds after 30 seconds, and the operation of bringing the V-yield metal 14 and the intake system of the engine 1 into communication is repeatedly performed for 4 to 30 seconds.

The abnormality determination routine will be explained in detail based on FIG. 5. In step 301, the control circuit 16 uses the pressure sensor 11 to determine whether the internal pressure in the fuel tank 7 is higher than a predetermined pressure. 302 purge valve 1
5 to stop exhausting fuel evaporative gas to the intake system. Then, in step 303, the control circuit 16 determines whether the determination condition is satisfied. This means that it is determined that the determination conditions are met when the feedback correction coefficient FAF at that time is within a predetermined range.

In step 304, the control circuit 16 determines whether or not the 02 Renly-6 is operating normally. This is 02'l? as shown in Figure 2. The voltage value of the output signal of the switch 6 is the boundary voltage V1. trr to see that it is changing by crossing V2
= 'y-koto (koyori (understood).

After confirming that the 02 sensor 6 is operating at positive tn' in step 304, the control circuit 16 checks the past value of the feedback correction coefficient "to" immediately before the skip process when the purge valve 15 is opened in step 305. Average value F for 6 times
A F 1 and the past 6 values of the feedback correction coefficient FΔF immediately before the skip process when the purge valve 15 is closed.
Compare the average value of batches with “λ” (difference between the two (F A F
2-Whether F A F 1 ) is greater than or equal to a predetermined value or less than a predetermined value>, it is determined whether the air-fuel ratio has become lean due to the purge valve 15 being closed from the open state of the purge valve 15.

That is, from the state where the fuel vapor adsorbed on the activated carbon of the canister 14 is being supplied into the intake pipe 2 by listening to the purge valve 15, the purge valve 15 is opened and the fuel vapor gas is supplied into the intake pipe 2. If the fuel evaporative gas diffusion prevention device is normal when the engine is stopped, the air-fuel ratio (FAF) will be lean as shown in FIG. However, if there is an abnormality in the fuel evaporative gas diffusion prevention device due to clogging of the purge pipe 13, as shown in FIG. The fuel ratio (FAF) is not lean.

If the control circuit 16 determines in step 305 that the lean condition is not present and that the condition is abnormal, the warning lamp 17 is turned on in step 306 to notify the U passenger. Further, when the cause of the abnormality in the fuel evaporative gas diffusion prevention device, such as the clogging of the purge pipe 13, is removed by the abnormality warning, the control circuit 16 determines that the system is lean in step 305, and turns off the warning lamp 17 in step 307. . Note that an appropriate delay may be provided for the start and end of the warning by the warning lamp 17.

As described above, according to this embodiment, the pressure sensor 1-11 detects the pressure inside the fuel tank 7, and when the pressure is equal to or higher than a predetermined pressure, it is determined that a sufficient amount of fuel has evaporated, and the purge is performed. The valve 15 is controlled to open and close the discharge passage 13a, and the air-fuel ratio (FAF) according to the 02'E' sensor 6 is adjusted at that time.
The presence or absence of an abnormality is determined based on the change in . Therefore, abnormalities such as clogging of the discharge passage 13a can be reliably detected and it can be confirmed that the fuel has been properly sucked and burned. In other words, it is possible to prevent the pressure inside the fuel tank 7 from becoming abnormally high or from evaporating a large amount of fuel through the safety valve 18 provided in the canister 14 during a popular event.

[Effects of the Invention] As described in detail above, according to the present invention, an abnormality in the fuel evaporative gas diffusion prevention device is determined and the fuel evaporative gas is properly inhaled and
It has an excellent effect of detecting combustion.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration around the engine of the embodiment, Fig. 2 is a time table showing various processes, Fig. 3 is a flowchart 1 to 1 to explain the operation of the embodiment, and Fig. 4 is a diagram of the embodiment. FIG. 5 is a flowchart for explaining the operation of the embodiment, and FIG. 6 is a time chart 1 to 6 showing various processes. 2 is an intake pipe, and 6 is an O? as an air-fuel ratio detection means. sensor,
7 is a fuel tank, 11 is a pressure sensor 1 as means for measuring pressure inside the tank, 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) Hironobu Diagram Diagram

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 in the fuel tank 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; and an in-tank pressure detection means for detecting the in-tank pressure in the fuel tank. , when the tank internal pressure detected by the tank internal pressure detection means is equal to or higher than a predetermined pressure, the opening/closing means is controlled to open and close the discharge passage, and the air-fuel ratio changes at that time by the air-fuel ratio detection means. 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.