JPH06159159A - Abnormality detecting device for vaporized fuel diffusion preventing device - Google Patents

Abstract

PURPOSE:To surely detect the leak abnormality by comparing the detected pressure between a control valve and a fuel tank with the preset value according to the vaporized fuel amount to be detected by a vaporized fuel amount detecting means. CONSTITUTION:A supply passage is communicated with a suction tube 2 from a fuel tank 13 through a canister 18 and a purge control valve 23. Abnormalities of a device are detected at every specified interval. When a vehicle is stopped in the idling condition, and the air fuel ratio correction factor (FAF) is smaller than 0.8, a judgement is made that the vaporized fuel amount to be supplied to the suction tube 2 is much, and the opening (thetai) of the purge control valve and the pressure in the fuel tank (PTANK) are read. On the other hand, when the FAF is larger than 0.8 and thetai is 90% or over, a judgement is made that the vaporized fuel amount to be supplied to the suction tube is small, and a judgement is made whether or not PTANK is equal to the set pressure 22.7mmHg or over, and the leak abnormality of the device is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detecting device for an evaporated fuel diffusion prevention device for detecting an abnormality in an evaporated fuel diffusion prevention device for preventing diffusion of evaporated fuel generated in a fuel supply system of an automobile.

[0002]

2. Description of the Related Art Conventionally, as an abnormality detecting device for an evaporated fuel diffusion preventing device of this type, for example, "an abnormality detecting device for a fuel evaporation preventing device" disclosed in Japanese Patent Application Laid-Open No. 2-130255.
It has been known. This device detects an abnormal supply of evaporated fuel to the intake pipe due to an abnormality in at least one of the canister, the supply passage, and the control valve based on the detected pressure between the control valve and the canister, and the evaporated fuel is released to the atmosphere. Is being detected.

[0003]

The above-described abnormality detecting device for the evaporated fuel diffusion preventing device compares the pressure in the supply passage at the time of executing the purge with a set value which is a constant value, and the detected pressure exceeds the set value. At this time, the supply abnormality of the evaporated fuel to the intake pipe is detected.

However, depending on the amount of evaporated fuel generated from the fuel tank or the amount of evaporated fuel adsorbed to the canister, the pressure in the supply passage may change even when the purge control valve is the same. Therefore, if the set value is set to a low value, when the detected pressure exceeds this set value, it will evaporate from the device to the atmosphere due to holes in the piping or fuel tank, or disconnection of the piping. There is a possibility that it may not be possible to clearly determine whether it is due to a leakage abnormality such as fuel leakage, or whether it is due to fuel vapor generated from the fuel tank or adsorbed in the canister. For this reason, a set value may be set at a pressure at which an abnormal leakage of the device is surely occurring (slightly lower than the atmospheric pressure in the prior art), but this detects that a minute abnormal leakage occurs. You may not be able to.

In view of the above problems of the prior art, it is an object of the present invention to provide an abnormality detecting device for an evaporated fuel diffusion preventing device for surely detecting an abnormality of the evaporated fuel diffusion preventing device.

[0006]

In order to achieve the above object, the present invention, as shown in FIG. 1, includes a canister having an adsorbent for adsorbing evaporated fuel generated in a fuel tank containing liquid fuel. A supply which communicates with the intake pipe of the internal combustion engine from the fuel tank through the canister and guides the evaporated fuel adsorbed by the adsorbent of the canister into the intake pipe by negative pressure generated in the intake pipe of the internal combustion engine A passage, a control valve that is provided in the supply passage between the fuel tank and the canister, and opens and closes the supply passage according to an operating state of the internal combustion engine, and between the fuel tank and the control valve. Pressure detecting means for detecting a pressure, and evaporative fuel amount detecting means for detecting at least one of the amount of evaporated fuel introduced into the intake pipe or the amount of evaporated fuel generated in the fuel tank. Abnormality detection means for comparing the pressure detected by the pressure detection means with a set value to detect an abnormality in at least one of the control valve, the canister, the fuel tank, and the supply passage, and the evaporated fuel amount detection And a changing means for changing the set value according to the amount of evaporated fuel detected by the means.

[0007]

According to the configuration of the abnormality detecting device for the evaporated fuel diffusion preventing device of the present invention described above, the supply passage is communicated from the fuel tank to the intake pipe via the canister and the control valve. The adsorbent provided in this canister adsorbs the evaporated fuel from the fuel tank, and the control valve opens and closes the supply passage according to the operating state of the internal combustion engine. Then, when the control valve is opened, the evaporated fuel adsorbed by the adsorbent by the negative pressure in the intake pipe is guided to the intake pipe. Further, the pressure detecting means detects the pressure between the fuel tank and the control valve, and the evaporated fuel amount detecting means detects at least one of the evaporated fuel amount introduced to the intake pipe and the evaporated fuel amount generated in the fuel tank. . Further, the abnormality detection means, the pressure detected by the pressure detection means,
By comparing the set value with the set value, any abnormality in at least one of the control valve, the canister, the fuel tank, and the supply passage is detected.

Here, the setting value is changed by the changing means according to the evaporated fuel amount detected by the evaporated fuel amount detecting means. For this reason, the detected pressure is compared by the set value changed according to the amount of evaporated fuel, so whether the pressure at this time is abnormal or the evaporated fuel from the fuel tank or the evaporated fuel adsorbed by the canister is compared. It is clearly discriminated whether it is due to. As a result, the abnormality of the device is surely detected.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a block diagram around the engine mounted on the automobile. An intake pipe 2 and an exhaust pipe 3 are connected to the engine 1. An air cleaner 4 that filters air is arranged upstream of the intake pipe 2, and the air is drawn into the intake pipe 2 via the air cleaner 4. Inside the intake pipe 2, a throttle valve 6 that opens and closes in conjunction with an accelerator pedal 5 is provided. A rotation speed control valve 8 is arranged so as to bypass the throttle valve 6. By adjusting the opening degree of the rotation speed control valve 8, the engine rotation speed can be changed by adjusting the intake air amount when the engine 1 is idling.

Air from the intake pipe 2 is supplied to the fuel chamber 10 via the intake valve 9. Exhaust gas in the fuel chamber 10 is exhausted to the exhaust pipe 3 via the exhaust valve 11. The exhaust pipe 3 is provided with an O ₂ sensor 12 as an air ratio detecting means.

On the other hand, a fuel tank 13 containing liquid fuel
Is connected to a fuel pump 14, and the fuel in the fuel tank 13 is conveyed by the fuel pump 14 under pressure. The fuel from the fuel pump 14 is supplied to a fuel injection valve 15 provided in the intake pipe 2, and the fuel is injected by opening and closing the fuel injection valve 15. Further, the fuel tank 13 is the communication pipe 1
6 is connected to the canister 17, and an adsorbent 19 for adsorbing the evaporated fuel, for example, activated carbon, is housed in the canister body 18. As a result, the fuel tank 1
Evaporated fuel generated in 3 is adsorbed by the adsorbent 19 of the canister 17 via the communication pipe 16.
Further, the canister body 18 is formed with an atmosphere opening hole 20 which is open to the atmosphere, so that air can be sucked into the inside. A pressure sensor 7 for detecting the pressure inside the fuel gas supply device is attached to the fuel tank 13.

Further, the fuel tank 13 has a built-in positive and negative pressure relief valve attached to a filler cap (not shown), which prevents the tank 13 from being crushed or expanded.

The canister body 18 has a hose connecting portion 21.
Is formed, and one end of the supply pipe 22 is inserted into the hose connection portion 21. The other end of the supply pipe 22 is connected to the purge control valve 23. One end of the supply pipe 24 is connected to the purge control valve 23, and the other end of the supply pipe 24 is connected to the intake pipe 2
It is connected to the. Therefore, the purge control valve 23 is interposed between the two supply pipes 22 and 24 so that the intake pipe 2 and the canister 17 can communicate with each other via the supply pipe 22, the purge control valve 23, and the supply pipe 24. . Then, in this communication state, the evaporated fuel adsorbed by the adsorbent 19 of the canister 17 can be guided into the intake pipe 2 by the negative pressure generated in the intake pipe 2 of the engine 1. The opening degree of the purge control valve 23 can be adjusted, and the purge flow rate passing through both supply pipes 22 and 24 is changed according to the opening degree. The supply pipes 22 and 24 are generally formed of a flexible material such as a rubber hose or a nylon hose.

The fuel tank 13, canister 17, purge control valve 23, communication pipe 16 and supply pipe 2 shown above.
The evaporative fuel diffusion preventing device 50 configured to supply the evaporative fuel generated in the fuel tank 13 to the intake pipe 2 and prevent the evaporative fuel from diffusing into the atmosphere is constituted by 2, 24 and the like.

Purge flow rate control, idle speed control, empty
Performs fuel ratio control, calculation of throttle opening variation, etc.
The electronic control circuit 25 acting as an abnormality detecting means is
U26, ROM27, RAM28, input / output circuit 29
And are connected to each other via the common bus 30.
There is. The ROM 27 has a control program for the CPU 26 and
The data is stored in advance, and the RAM 28 can be read and written.
Has become. The CPU 26 receives various data via the input / output circuit 29.
The signal of is input. That is, O ₂Sensor
Water from the signal from 12 and the temperature of the engine cooling water
The signal from the temperature sensor 31 and the opening degree of the throttle valve 6
Signal from the throttle opening sensor 39 for detecting
Id that turns on when the accelerator pedal 5 is not depressed
Signal from the vehicle switch 35 and the signal from the vehicle speed sensor 36.
And a rotation speed sensor 37 for detecting the engine rotation speed,
From the air flow meter 32 that detects the engine intake air amount
Input the signal.

The CPU 26 then sends these signals, R
The fuel injection valve 15, the purge control valve 23, and the rotation control valve 8 are drive-controlled via the input / output circuit 29 based on programs and data in the OM 27 and RAM 28.

That is, the CPU 26 adjusts the opening degree of the purge control valve 23 according to the operating state of the engine 1 to adjust the opening of the purge control valve 23.
Control the purge flow rate of 2,24. That is, the purge control valve opening is calculated and controlled by the CPU 26 so that the purge flow rate becomes a predetermined ratio with respect to the intake amount by the air flow meter 32. Further, the CPU 26 controls the intake air amount by adjusting the opening degree of the rotation speed control valve 8 so as to reach the target rotation speed during the idle operation of the engine 1, and further controls the intake air amount detected by the O ₂ sensor 12 to the engine 1. The air-fuel ratio of the air-fuel mixture is controlled to be constant. That is, CPU2
6 is a basic injection time obtained from the engine speed by the rotation speed sensor 37 and the intake amount by the air flow meter 32.
The basic injection time is corrected by the feedback correction coefficient FAF or the like to obtain the final injection time, and the fuel injection is performed at the injection timing of the range by the fuel injection valve 15.

A warning lamp 38 as warning means is provided on the instrument panel of the vehicle and is connected to the CPU 26 via the input / output circuit 29. Next, the operation of the self-diagnosis device in the evaporated fuel diffusion prevention device thus constructed will be described.

First, the feedback control of the air-fuel ratio is shown in FIG.
A description will be given based on the flowchart. This process is executed every predetermined time. As shown in FIG. 3, the CPU 26 compares the output voltage of the O ₂ sensor 12 with the comparison voltage to determine whether the mixture is rich or lean. And the CPU 26
In step 100, it is determined whether or not the condition for the field back control is satisfied. It is determined that the conditions are met when the engine water temperature by the water temperature sensor 31 is 40 ° C. or higher and the throttle opening by the throttle opening sensor 39 is 70 ° or less. CPU26
If the condition is not satisfied, the feedback correction coefficient FAF = 1.0 is set in step 101.

When the feedback control condition is satisfied, the CPU 26 determines from the signal from the O ₂ sensor 12 whether or not the air-fuel ratio is rich in step 102. If it is rich, the previous detection result is obtained in step 103. It is determined whether or not the lean is reversed to the rich by comparing with.
When the lean-to-rich inversion is performed, the CPU 26 sets the feedback correction coefficient FAF-α (α is a skip amount) as a new feedback-correction coefficient FAF in step 104, and if there is no lean-to-rich inversion, the CPU 26 proceeds to step 1
At 05, the feedback correction coefficient FAF-β (β is an integral amount, α> β) is set as a new feedback correction coefficient.

In the case of lean in step 102, the CPU 26 compares in step 106 with the previous detection result to determine whether the state is reversed from rich to lean. When the CPU 26 reverses from rich to lean, the feedback correction coefficient FAF + α (α is a skip amount) is set as a new feedback correction coefficient FAF in step 107, and when there is no inversion from rich to lean, the feedback correction coefficient FAF + β (β Is a new feedback correction coefficient FAF.

Accordingly, if there is a reversal between rich and lean by the processing of steps 102 to 108, the feedback correction coefficient FAF is changed stepwise (skip) to increase or decrease the fuel injection amount, and at the same time, rich or lean Sometimes, the feedback correction coefficient FAF is gradually increased or decreased.

FIG. 4 shows an abnormality detection process for the evaporated fuel diffusion preventing device 50, which is executed every required time. This process
Abnormality is detected, such as when a hole is opened somewhere in the device 50 for some reason or when the piping is disconnected and the evaporated fuel leaks into the atmosphere, or when the atmosphere opening hole 20 of the canister 17 is clogged. To do.

First, in step 201, | PTANK
It is determined whether or not | <40 (mmHg). This determines whether the fuel tank internal pressure PTANK is within the set pressure of the positive and negative pressure relief valves built in the filler cap of the fuel tank 13. If it is within the set pressure, the process proceeds to step 202, and if it is outside the set pressure, the process proceeds to step 250 to set the abnormal mode.

In step 202, the vehicle speed is 2 (k
m / h), it is determined whether the vehicle is stopped or not. Further, in step 203, it is determined whether or not the idle switch is turned on. By these steps 202 and 203, it is determined whether or not the vehicle is in a stable state such as stopped and idling. Then, if the vehicle is in a stable state, the routine proceeds to step 204, and if not, this routine is ended.

Next, at step 204, the current feedback correction coefficient FAF calculated in FIG. 3 is read. Then, at step 205, it is judged if this FAF is larger than 0.8. If FAF is larger than 0.8, the routine proceeds to step 206, where the opening degree θi of the purge control valve 23 is 90.
(%) Or more, and it is determined whether the control valve 23 is almost fully opened. The opening θi is 90
If it is above (%), the routine proceeds to step 207, where it is judged if the fuel tank internal pressure PTANK is below the set value -22 (mmHg). And PTANK is -22 (mmH
If g) or less, the routine proceeds to step 208, where it is judged that the evaporated fuel diffusion preventing device 50 is normal, and the normal mode is set.

On the other hand, at step 206, the opening θi is set to 90.
If it is less than (%), the routine proceeds to step 209, where the opening θi of the control valve 23 is set to θi + α (%) (α is a predetermined value), the opening is increased, and this routine is ended.

On the other hand, in step 205, FAF is 0.8.
If smaller, proceed to step 210 and FAF is 0.8
If it is determined that FAF is 0.8, the process proceeds to step 220. And step 2
At 20, the opening θi of the control valve 23 at this time is read,
In step 230, PTANK at this time is read. Next, in step 230, steps 210, 220
In step 250, it is determined whether or not the value at this time is in the abnormal region by searching the abnormality detection map shown in FIG. If the current value is in the abnormal region, the abnormal mode is set in step 260, and if the current value is outside the abnormal region, the normal mode is set in step 208, and the routine ends.

In step 210, FAF is set to 0.8.
If not, the routine proceeds to step 270, where the opening degree θi of the control valve 23 is set to θi-β (%) (β is a predetermined value), the opening degree is decreased, and this routine is ended.

When the purge control valve 23 is opened when the vehicle is in a stable state, the evaporated fuel is supplied to the intake pipe 2, and the evaporated fuel and the fuel injected from the fuel injection valve 15 are in the combustion chamber. Inhaled to 10. On the other hand, air cleaner 4
The air sucked through the air is sucked into the combustion chamber 10 together with the air supplied from the purge control valve 23. As a result, the value of the feedback correction coefficient FAF changes.
For example, when the amount of evaporated fuel in the gas from the device 50 to the intake pipe 2 is small, the value of FAF increases, and when the amount of evaporated fuel in the gas is large, the value of FAF decreases.

In this embodiment, since the intake air amount is detected by the air flow meter 32, the control valve 23
The amount of air flowing into the intake pipe 2 from is not taken into consideration. Therefore, when the gas sucked into the intake pipe 2 from the device 50 is mostly air, the value of FAF becomes larger than 1.0 which shows the theoretical air-fuel ratio, and the gas contains a large amount of evaporated fuel. In this case, the FAF value may be smaller than 1.0. On the other hand, instead of detecting the intake air amount with the air flow meter, the pressure of the intake pipe 2 is detected, and the basic injection time is calculated based on this pressure value and the number of revolutions. The air from the control valve 23 is also taken into consideration because the intake pipe pressure changes depending on the gas that flows. Therefore, unlike the above embodiment, the value of FAF increases or decreases with a value smaller than 1.0.

Here, in step 210 of the above processing, F
When AF becomes 0.8, the routine proceeds to step 220, where the opening degree θi of the purge control valve 23 is read. At this time,
The amount of evaporative fuel generated in the device 50 can be estimated from the current θi read in step 220.

That is, when the vehicle is in a stable state and FAF
It can be estimated that the amount of evaporated fuel supplied from the device 50 to the intake pipe 2 when is about 0.8 is a predetermined amount. At this time, if the opening degree θi of the purge control valve 23 is small, the purge flow rate is small. Therefore, it can be determined that the amount of evaporated fuel with respect to the gas from the device 50 is large and the amount of evaporated fuel generated in the device 50 is large. On the other hand, if the opening degree θi of the control valve 23 is large, the purge flow rate is large, so that it can be determined that the amount of evaporated fuel with respect to the gas from the device 50 is small and the amount of evaporated fuel generated in the device 50 is small. Accordingly, when the feedback correction coefficient FAF is around 0.8, the device 5
The amount of evaporated fuel generated within 0 can be detected according to the opening degree θi.

Then, as shown in the abnormality detection map of FIG. 5, the set pressure is set according to the opening degree θi, and step 2
The abnormality detection is executed by comparing PTANK read in 30 with this set value.

According to the map search of FIG. 5, PTANK at θi detected this time is the evaporated fuel generated in the fuel tank 13 due to the negative pressure introduced into the device 50 from the intake pipe 2 and the evaporation absorbed in the canister 17. The pressure rise caused by the fuel, or the device 50
It can be clearly discriminated whether or not the pressure increase caused by the leakage abnormality inside is added. Then, the former of this pressure value can be discriminated as the normal region, and the latter of the latter can be discriminated as the abnormal region 1, and the leakage abnormality of the device 50 can be surely detected.

When the inside of the device 50 becomes too negative, such as when the atmosphere opening hole 20 of the canister 17 is clogged, the values read by the sleeves 210 and 220 are as shown in the abnormal area 2 in FIG. Become. Thereby, the abnormality can be detected.

On the other hand, when the FAF is larger than 0.8 and the opening degree of the control valve 23 is near the fully open state, the amount of evaporated fuel in the gas supplied from the device 50 to the intake pipe 2 is small, and the inside of the device 50 is small. It is determined that the amount of evaporated fuel generated in step 2 is considerably small, and in step 207, PTANK at this time is compared with the set value (-22 (mmHg) in this embodiment). If PTANK is less than or equal to this set value, it is normal, and if PTANK is greater than or equal to the set value, it can be detected that the device 50 has a leakage abnormality.

When the engine speed, the intake air amount, the vehicle speed, and the like are constant for a predetermined time while the vehicle is traveling, the vehicle may be detected as being in a stable state and the above processing may be executed.

Here, in the above processing, step 209
The opening θi is gradually increased by the
When it is determined that the amount of evaporated fuel generated in the inside is small, the purge flow rate supplied from the device 50 to the intake pipe 2 is increasing, so that PTANK during normal operation and leakage abnormality in the device 50 occur. The difference from PTANK when the player is on Therefore, the abnormality detection determination can be easily performed.

Further, although the pressure sensor 7 is provided in the fuel tank 13 in this embodiment,
It may be provided up to the control valve 23. In the above embodiment, when the FAF is around 0.8, the amount of evaporated fuel generated in the device 50 is detected, but the set value of this FAF is not limited to 0.8. However, fuel injection valve 1
The FAF value which is less than the minimum injection time of 5 is not reached.

Further, an abnormality detection map for the opening θi of each FAF is created, and the calculated FAF is detected,
The abnormality may be detected by a map according to this FAF. Further, as in the above embodiment, the amount of evaporated fuel generated in the device 50 is detected by FAF and θi. However, the supply pipe 24 between the control valve 23 and the intake pipe 2 is provided with means for detecting the concentration of the evaporated fuel, and the device 5 is provided by this means.
The amount of evaporated fuel supplied to the intake pipe 2 from 0 may be detected, and the amount of evaporated fuel generated in the device 50 may be detected by this evaporated fuel amount and θi. Further, if this concentration detecting means is provided in the supply pipe 22, it is possible to directly detect the amount of evaporated fuel generated in the device 50.

Further, it can be judged that the amount of evaporated fuel generated in the tank 13 is large when the sensor detection value of the pressure sensor 7 is large, and the amount of evaporated fuel is small when the detection value is small. Therefore, the pressure sensor 7 may detect the amount of evaporated fuel generated in the fuel tank 13. Further, a means for detecting the fuel concentration may be provided in the fuel tank 13 or the communication pipe 16 to detect the amount of evaporated fuel generated in the fuel tank 13.

[0043]

According to the configuration and operation of the abnormality detecting device for an evaporated fuel diffusion preventing device of the present invention described above, the detected pressure between the control valve and the fuel tank is detected by the evaporated fuel amount detecting means. Since the comparison is made based on the set value according to the amount of evaporated fuel, it is possible to clearly determine whether the pressure at this time is due to an abnormality in the device leakage, evaporated fuel from the fuel tank, or evaporated fuel adsorbed in the canister. it can. Therefore, it is possible to reliably detect the leakage abnormality of the device and further detect that the evaporated fuel is released to the atmosphere.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of the present invention.

FIG. 2 is a configuration diagram around an engine according to an embodiment of the present invention.

FIG. 3 is a flowchart showing air-fuel ratio feedback.

FIG. 4 is a flowchart showing an abnormality detection routine.

FIG. 5 is an abnormality detection map.

[Explanation of symbols]

 2 Intake pipe 7 Pressure sensor 12 O2 sensor 13 Fuel tank 15 Fuel injection valve 16 Communication pipe 17 Canister 22 Supply pipe 23 Purge control valve 24 Supply pipe 25 Electronic control circuit

Claims (1)

[Claims] 1. A canister having an adsorbent for adsorbing evaporated fuel generated in a fuel tank containing a liquid fuel, and a canister communicating with the intake pipe of the internal combustion engine from the fuel tank via the canister. Is provided in the supply passage between the fuel tank and the canister, the supply passage introducing the evaporated fuel adsorbed by the adsorbent into the intake pipe of the internal combustion engine by the negative pressure generated in the intake pipe of the internal combustion engine. A control valve that opens and closes the supply passage according to an operating state of the engine, a pressure detection unit that detects a pressure between the fuel tank and the control valve, an amount of evaporated fuel introduced into the intake pipe, or the fuel. The evaporated fuel amount detecting means for detecting at least one of the evaporated fuel amount generated in the tank, the pressure detected by the pressure detecting means and a set value are compared, and the control valve Abnormality detecting means for detecting an abnormality in at least one of the canister, the fuel tank, and the supply passage; and a changing means for changing the set value according to the amount of evaporated fuel detected by the amount of evaporated fuel detecting means. An abnormality detection device for an evaporated fuel diffusion prevention device, comprising: