JPH09151812A - Abnormality detecting device for fuel transpiration preventing mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve precision of detection of abnormality, such as leakage of fuel gas by absorbing the influence of an operation state and unevenness of an actuator itself. SOLUTION: Fuel gas generated in a fuel tank 22 and adsorbed by an adsorbent 34 of a canister 30 is properly discharged in an intake pipe 2 according to control of opening and closing of a purge control valve 40. When abnormality of a fuel transpiration preventing mechanism is detected, when a negative pressure is introduced to a fuel transpiration preverzting mechanism through given control of opening and closing of the purge control valve 40 and a canister closing valve 37, an integrating value of respective pressure changes when a negative pressure is held is calculated, and based on the integrating value, decision of the abnormality is executed. This constitution prevents an influence from being exercised by a change in an operation state and unevenness of the purge control valve 40 and the canister closing valve 37 itself, resulting in improvement of detection precison.

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 a fuel evaporation preventing mechanism for detecting an abnormality such as a fuel gas leak in a fuel evaporation preventing mechanism for preventing evaporation of fuel gas generated in a fuel tank. .

[0002]

2. Description of the Related Art Conventionally, in automobiles and the like, a fuel evaporation prevention mechanism is obliged to be installed in order to prevent the fuel gas generated in a fuel tank from being released into the atmosphere. This fuel evaporation prevention mechanism adsorbs fuel gas at any time by an adsorbent of a canister arranged in the middle of a purge passage that connects a fuel tank and an intake pipe, and a purge control valve is activated according to the operating state of an internal combustion engine. By opening and closing,
This is a mechanism for preventing the evaporation of fuel by appropriately introducing the adsorbed fuel gas into the intake pipe and mixing it in the fuel mixture.

In such a fuel evaporation prevention mechanism, a purge passage is usually formed by connecting a canister and an intake pipe with a rubber hose. When this rubber hose is bent and crushed, the fuel gas is not introduced into the intake pipe, exceeds the fuel gas adsorption capacity of the adsorbent in the canister, and the fuel gas is released from the air holes.
Further, since the rubber hose is in contact with the alcohol component, it may be damaged due to corrosion or the like, and if the atmospheric hole of the canister is clogged with dust or the like, it may be removed due to pressure increase. In this case as well, the fuel gas will be released to the atmosphere.

Therefore, as a prior art document relating to an abnormality detecting device for a fuel evaporation prevention mechanism for detecting the occurrence of such a situation, one disclosed in Japanese Patent Laid-Open No. 5-125997 is known.

In this system, the atmospheric hole of the canister is closed by a canister closing valve, the purge control valve is opened to introduce a negative pressure from the intake pipe into the fuel evaporation prevention mechanism, and then the purge control valve is closed and closed. A technique is disclosed in which the amount of change in pressure is monitored to detect an abnormality such as a fuel gas leak in a fuel evaporation prevention mechanism.

[0006]

By the way, the amount of change in negative pressure is greatly affected by the amount of fuel remaining in the fuel evaporation prevention mechanism, that is, the space volume. If the space volume is small, the amount of change in negative pressure is large even with a small amount of leakage, and conversely, if the space volume is large, it is indistinguishable from a large amount of leakage. Therefore, it is necessary to provide a fuel gauge or the like in the fuel tank to newly take in the signal to obtain the remaining fuel amount and correct the determination value in the abnormality detection. However, there is a problem that the increase in the number of parts causes a cost increase.

As a prior art document for dealing with this, the one disclosed in Japanese Patent Publication No. 6-506751 is known. By using the ratio of the pressure change when the negative pressure is introduced and the pressure change when the negative pressure is held, the fuel gas is not affected by the space volume without providing a fuel gauge in the fuel tank. Techniques are disclosed that enable detection of abnormalities such as leakage.

However, when the negative pressure is introduced into the fuel evaporation prevention mechanism, the negative pressure change is easily affected by the change of the intake pressure and the variation of the purge control valve, and the division is frequently used during the calculation, so that the abnormality detection accuracy is high. There was a problem that the reliability of the was decreased.

Therefore, the present invention has been made to solve such a problem, and absorbs the influence of the change in the operating state and the variation of the actuator itself when the abnormality such as the fuel gas leakage of the fuel evaporation prevention mechanism is detected. An object of the present invention is to provide an abnormality detection device for a fuel evaporation prevention mechanism, which can improve detection accuracy by simplifying calculation.

[0010]

According to the abnormality detecting apparatus for a fuel evaporation prevention mechanism of the first aspect, the intake pipe accompanying the predetermined opening / closing control of the purge control valve and the air hole closing means by the first integrated value calculating means. The integrated value of the pressure change when the negative pressure is introduced into the fuel evaporation prevention mechanism is calculated from the second integrated value calculation means, and the negative value of the fuel evaporation prevention mechanism associated with the predetermined opening / closing control of the purge control valve and the air hole closing means is calculated by the second integrated value calculation means. An integrated value of the pressure change at the time of maintaining the pressure is calculated, and the abnormality detecting means detects the abnormality of the fuel evaporation prevention mechanism based on the integrated value. As a result, when an abnormality such as a fuel gas leak of the fuel evaporation prevention mechanism is detected, it is not affected by the change of the operating state and the variation of the purge control valve and the air hole closing means itself, so that the detection accuracy is improved. can get.

According to the abnormality detecting apparatus for the fuel evaporation preventing mechanism of the second aspect, the first time measuring means transfers the intake pipe to the fuel evaporation preventing mechanism by the predetermined opening / closing control of the purge control valve and the air hole closing means. The time of pressure change at the time of introducing the negative pressure is measured, and the time of pressure change at the time of maintaining the negative pressure of the fuel evaporation prevention mechanism accompanying the predetermined opening / closing control of the purge control valve and the atmospheric hole closing means by the second time measuring means Measured,
The abnormality detecting means detects an abnormality in the fuel evaporation prevention mechanism based on the times. As a result, when an abnormality such as a fuel gas leak of the fuel evaporation prevention mechanism is detected, it is not affected by changes in the operating state and variations in the purge control valve and the air hole closing means itself, and the calculation is simplified. The effect of improving the detection accuracy can be obtained.

In the fuel vaporization prevention mechanism abnormality detection device of the third aspect, the abnormality detection means of the first or second aspect uses the ratio or the quotient in the calculation for detecting the abnormality of the fuel vaporization prevention mechanism, and thus the space Since the influence of the size of the volume is eliminated, the detection accuracy is improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples.

<Embodiment 1> FIG. 1 is a schematic configuration diagram showing an abnormality detecting device for a fuel evaporation preventing mechanism according to a first embodiment of the present invention.

In FIG. 1, air sucked through an air cleaner 1 for filtering air is supplied to an intake pipe 2 connected to the air cleaner 1. Inside the intake pipe 2, a throttle valve 8 that is opened and closed in conjunction with an accelerator pedal 6 is provided. The intake pipe 2 includes a piston 12 and a cylinder head 14 of the internal combustion engine 3 via an intake valve 10.
It is connected to the combustion chamber 16 formed by Further, the combustion chamber 16 is connected to an exhaust pipe 20 via an exhaust valve 18.

On the other hand, a fuel pump 24 for pressurizing and supplying the liquid fuel contained in the fuel tank 22 and an injector (fuel injection valve) 26 arranged in the intake pipe 2 are connected,
It is configured to control the opening and closing of the injector 26 to inject fuel. Further, the communication pipe 28 connected to the fuel tank 22 is connected to the canister 30. Activated carbon, for example, is contained in the canister body 32 as an adsorbent 34 that adsorbs fuel gas. As a result, the canister 30 can adsorb the fuel gas generated in the fuel tank 22 via the communication pipe 28. Further, an air hole 36 for opening to the atmosphere is formed in the canister body 32 so that air can be sucked into the inside. A canister closing valve 37 for closing the atmosphere hole 36 is provided in the atmosphere hole 36 as needed.

The canister closing valve 37 closes the atmosphere hole 36 of the canister body 32 when a predetermined voltage is applied, and introduces the atmosphere from the atmosphere hole 36 of the canister body 32 when the predetermined voltage is not applied. It is a solenoid valve.

Further, one end of the supply pipe 38 is inserted into the hose connecting portion 32a of the canister body 32 and connected to the canister 30, and the other end of the supply pipe 38 is connected to the purge control valve 40. One end of a supply pipe 42 is connected to the purge control valve 40, and the other end of the supply pipe 42 is connected to the intake pipe 2. Supply pipe 3 used here
Reference numerals 8 and 42 are flexible hoses such as rubber hoses and nylon hoses, and are entirely formed. Also, the fuel tank 2
The communication pipe 28 connecting the 2 and the canister 30 is also partially formed of a rubber hose or the like.

The fuel tank 22 is connected by the supply pipes 38, 42 and the communication pipe 28 connected to the purge control valve 40.
To the intake pipe 2 constitute a purge passage. The purge control valve 40 is interposed between the two supply pipes 38 and 42 to switch the intake pipe 2 and the canister 30 between communication and non-communication. It is configured to connect and disconnect 42.

The purge control valve 40 is in a purged state in the opening direction when a predetermined pulse signal is applied to the passage between the canister 30 side to which the supply pipe 38 is connected and the intake pipe 2 side to which the supply pipe 42 is connected. It is a solenoid valve. The purge flow rate of the fuel gas from the canister 30 to the intake pipe 2 can be controlled by continuously changing the ratio (duty ratio) of the pulse width to the cycle of the pulse signal.

The fuel tank 22 has a fuel tank internal pressure PTNK.
A pressure sensor 44 for detecting is detected. Further, the fuel tank 22 has a relief valve 22 for releasing pressure when the internal pressure exceeds -40 mmHg to 150 mmHg.
a is provided. Therefore, the section from the fuel tank 22 to the canister 30 is always suppressed to be equal to or less than the pressure fluctuation within this relief pressure range. Therefore, as the pressure sensor 44, it is sufficient to adopt a structure that can withstand the relief pressure range.

These injector 26, canister closing valve 37, purge control valve 40 and pressure sensor 4
4 is connected to an ECU (Electronic Control Unit) 50. The ECU 50 is configured as a logical operation circuit including a CPU 52 as a well-known central processing unit, a ROM 54 in which control programs and maps are stored in advance, a RAM 56 for storing various data, an input / output circuit 58, a common bus 60 connecting them, and the like. Has been done. A throttle opening sensor 62, an idle switch 64, a vehicle speed sensor 66, etc. are connected to the input / output circuit 58. The CPU 52 in the ECU 50 uses the injector 26, the canister closing valve 37, and the purge control valve based on the signals input from the various sensors through the input / output circuit 58 and the control programs and various data stored in the ROM 54 and the RAM 56. Each drive signal is output to 40 or the like via the input / output circuit 58. Thus,
The ECU 50 executes fuel injection control, canister purge control, fuel evaporation prevention mechanism abnormality detection control, and the like.

Next, the ECU 50 used in the abnormality detecting device for the fuel evaporation preventing mechanism according to the first embodiment of the present invention.
An abnormality detection processing procedure in the CPU 52 will be described based on the flowchart of FIG. 2 and with reference to the time chart of FIG.

First, in step S101, it is determined whether or not the condition for executing the abnormality detection for the present system as the fuel evaporation prevention mechanism is satisfied. This execution condition is
For example, it is not determined, the vehicle is stopped, idling, and other failure diagnosis affecting the system is not being performed.
When the execution condition of step S101 is not satisfied, this routine is ended. On the other hand, when the execution condition of step S101 is satisfied, the process proceeds to step S102, the canister closing valve 37 is closed, and then step S
At 103, the counter S1 for obtaining the integrated value of the negative pressure change ratio is initialized to 0, and at step S104, the counter CNT1 for counting the integrated time is initialized to the initial value T1.

Next, at step S105, the purge control valve 40 is opened at a predetermined duty ratio, and the introduction of the negative pressure in the intake pipe 2 into this system is started (time in FIG. 3). t0). Next, the routine proceeds to step S106, where the measured fuel tank internal pressure PTNK is added to the counter S1. Next, the process proceeds to step S107, and the counter CNT1 is decremented. Next, step S10
8, the counter CNT1 becomes 0, and it is determined in step S105 whether the predetermined time T1 has elapsed since the purge control valve 40 was opened.

When the determination condition of step S108 is not satisfied, the processes of steps S106 to S108 are repeated, and when CNT1 = 0 in step S108 (time t1 in FIG. 3), the process proceeds to step S109. In step S109, the purge control valve 40 is closed and the introduction of negative pressure is stopped (time t2 in FIG. 3).

Next, as the integration processing of the negative pressure change rate at the time of holding the negative pressure, first, the process proceeds to step S110, and the counter S2 for obtaining the integrated value of the negative pressure change rate has the initial value 0,
In step S111, the counter CNT2 for counting the integrated time is initialized to the initial value T2. Next, the routine proceeds to step S112, where the fuel tank internal pressure PTNK at this time is stored as its initial value PTNKO. This initial value PTNKO is necessary as the first value at the start of change in order to calculate the change rate.

Next, in step S113, the amount of change (deviation) between the initial value PTNKO stored in step S112 and the current fuel tank internal pressure PTNK is added to the counter S2. Next, the process proceeds to step S114, and the counter C
NT2 is decremented. Next, the process proceeds to step S115, the counter CNT2 becomes 0, and step S1
At 09, it is determined whether the predetermined time T2 has elapsed since the purge control valve 40 was closed.

When the determination condition of step S115 is not satisfied, the processes of steps S113 to S115 are repeated, and when CNT2 = 0 in step S115 (time t3 in FIG. 3), the process proceeds to step S116. In step S116, the canister closing valve 37 is opened, and the canister 30 of the present system is brought into the atmosphere-introducable state (time t4 in FIG. 3).

Next, in order to detect whether or not there is an abnormality such as fuel gas leakage using the integrated values S1 and S2 of the fuel tank internal pressure PTNK measured as described above, step S
Moving to 117, the area ratio SCHK is calculated by the following equation (1). At this time, since the value changes depending on the difference in sampling time (number of times), standardization is performed at T1 and T2, respectively. Normally, T1 and T2 are sufficient, but since the ratio is calculated based on the area in this embodiment, (T1) ² , (T
2) Standardized in ² .

[0031]

## EQU1 ## SCHK = {S2 / (T2) ² } / {S1 / (T1) ² } (1) Then, the process proceeds to step S118, where the area ratio SCHK calculated in step S117 is the fuel gas. It is judged whether or not the judgment value SREF for detecting an abnormality such as leakage is exceeded. When the determination condition of step S118 is satisfied, the process proceeds to step S119, it is determined that there is an abnormality such as fuel gas leakage, the abnormality flag is turned on (set), and this routine is ended. On the other hand, the determination condition of step S118 is not satisfied,
When the area ratio SCHK is less than or equal to the determination value SREF, the process proceeds to step S120, it is determined that there is no abnormality such as fuel gas leakage, the abnormality flag is turned off (cleared), and this routine ends.

Incidentally, step S in the above-mentioned routine.
The relationship between the denominator and the numerator in the calculation of the area ratio SCHK 117 may be reversed. However, in that case, step S
It goes without saying that the judgment value SREF of 118 and the direction of the inequality sign need to be changed.

FIG. 4 shows the area ratio SCHK and the judgment value S used in the abnormality detection device for the fuel evaporation prevention mechanism according to this embodiment.
FIG. 6 is a characteristic diagram showing the relationship with REF using the fuel amount [%] in the fuel tank 22 as a parameter.

As shown in FIG. 4, when there is no fuel gas leakage in the fuel evaporation prevention mechanism, the area ratio SCHK is 0 and increases as the leakage diameter changes from φ1.0 to φ2.0, but the fuel amount increases. The value is almost the same regardless of. Therefore, in order to detect an abnormal fuel gas leakage with a diameter of φ1.0 or more, the judgment value SREF should be set to a value slightly smaller than the area ratio SCHK for a leakage diameter of φ1.0 (a value that takes into consideration the influence of variations). You can see that you should set it.

As described above, the abnormality detecting apparatus for the fuel evaporation prevention mechanism of this embodiment is provided with the purge passage formed by the communication pipe 28 and the supply pipes 38, 42 which communicate the fuel tank 22 with the intake pipe 2 of the internal combustion engine 3. The adsorbent 34 of the canister 30 provided midway adsorbs the fuel gas generated in the fuel tank 22 at any time, and the purge control valve 40 is opened / closed according to the operating state of the internal combustion engine 3 to adsorb the adsorbed fuel. The fuel vaporization preventing mechanism for appropriately introducing gas into the intake pipe 2 to prevent fuel vaporization, the pressure detecting means including the pressure sensor 44 for detecting the pressure state in the fuel vaporization preventing mechanism, and the canister 30 are provided. Atmosphere hole closing means including a canister closing valve 37 capable of closing the air hole 36, and a predetermined opening / closing control for the purge control valve 40 and the atmosphere hole closing means. A first integrated value calculation means that is achieved by the CPU 52 in the ECU 50 that calculates an integrated value S1 of the pressure change detected by the pressure detection means when the negative pressure is introduced from the trachea 2 to the fuel evaporation prevention mechanism, and purging. An EC for calculating an integrated value S2 of pressure changes detected by the pressure detection unit when the fuel vaporization prevention mechanism holds a negative pressure due to a predetermined opening / closing control of the control valve 40 and the air hole closing unit.
The fuel based on the second integrated value computing means achieved by the CPU 52 in the U50, and the respective integrated values S1 and S2 calculated by the first integrated value computing means and the second integrated value computing means. ECU 5 for detecting abnormality of evaporation prevention mechanism
And an abnormality detecting means achieved by the CPU 52 in 0.

Therefore, the adsorbent 34 of the canister 30 to which the fuel gas generated in the fuel tank 22 is adsorbed at any time
From the purge control valve 4 depending on the operating state of the internal combustion engine 3.
A fuel transpiration prevention mechanism that is appropriately introduced into the intake pipe 2 via 0 to prevent fuel transpiration, and the CPU 52 in the ECU 50 as the first integrated value calculation means uses the purge control valve 40 and the air hole blocking means. The integrated value S1 of the pressure change when the negative pressure is introduced from the intake pipe 2 to the fuel evaporation prevention mechanism according to the predetermined opening / closing control of the canister closing valve 37 is calculated, and the integrated value S1 in the ECU 50 as the second integrated value calculating means is calculated. The CPU 52 calculates the integrated value S2 of the pressure change when the negative pressure of the fuel evaporation prevention mechanism is maintained in accordance with the predetermined opening / closing control of the purge control valve 40 and the canister closing valve 37, and the CPU 52 in the ECU 50 as the abnormality detecting means integrates them. An abnormality of the fuel evaporation prevention mechanism is detected based on the values S1 and S2. As a result, when an abnormality such as a fuel gas leakage of the fuel evaporation prevention mechanism is detected, the detection accuracy is improved because it is not affected by the change of the operating state and the variation of the purge control valve 40 and the canister closing valve 37 itself.

Further, in the abnormality detecting apparatus for the fuel evaporation prevention mechanism of this embodiment, the abnormality detecting means achieved by the CPU 52 in the ECU 50 uses the ratio or the quotient in the calculation of the abnormality detection of the fuel evaporation preventing mechanism. is there. Therefore, since the CPU 52 in the ECU 50 as the abnormality detecting means is not affected by the size of the space volume by using the ratio or the quotient for the calculation, the accuracy of the abnormality detection of the fuel evaporation prevention mechanism is improved.

<Embodiment 2> FIG. 5 is a flow chart showing the procedure of abnormality detection in the CPU 52 in the ECU 50 used in the abnormality detection device for the fuel evaporation prevention mechanism according to the second embodiment of the present invention. 6 is a time chart corresponding to the flowchart of FIG.
The configuration of the abnormality detection device for a fuel evaporation prevention mechanism according to the present embodiment is the same as the schematic diagram of FIG. 1 in the above-described first embodiment, and therefore detailed description thereof will be omitted.

Below, based on the abnormality detection routine of FIG.
This will be described with reference to the time chart of FIG.

First, in step S201, it is determined whether the condition for executing the abnormality detection for the present system as the fuel evaporation preventing mechanism is satisfied. This execution condition is
Similar to the first embodiment described above, for example, it is undetermined, the vehicle is stopped, the engine is idling, and other failure diagnosis affecting the system is not being performed. When the execution condition of step S201 is not satisfied, this routine is ended. On the other hand, when the execution condition of step S201 is satisfied,
The process proceeds to step S202, and the canister closing valve 37
Is closed, the counter T1 for measuring time is initialized to an initial value 0 in step S203.

Next, in step S204, the purge control valve 40 is opened at a predetermined duty ratio, and the introduction of the negative pressure in the intake pipe 2 into this system is started (time in FIG. 6). t00). Next, the process proceeds to step S205, and the counter T1 is incremented. Next, the routine proceeds to step S206, where the measured fuel tank internal pressure PTN
It is determined whether K has reached less than a predetermined negative pressure PREF1. As the predetermined negative pressure PREF1, for example, a value of about −10 mmHg is set. Steps S205 and S206 are repeated until the fuel tank internal pressure PTNK becomes less than the predetermined negative pressure PREF1, and the time until the pressure reaches less than the predetermined negative pressure PREF1 is counted by the counter T1. When the determination condition of step S206 is satisfied, the counting of the counter T1 is stopped and the counter value T1 is stored (time t01 in FIG. 6).

Next, in step S207, for example, as the negative pressure PBOOST necessary for the abnormality detection when the negative pressure is held,
Negative pressure is further introduced until it becomes less than -20 mmHg. When the determination condition of step S207 is satisfied and the fuel tank internal pressure PTNK becomes less than the negative pressure PBOOST, step S2
Then, the purge control valve 40 is closed and the introduction of the negative pressure is stopped (time t02 in FIG. 6). Next, step S2
At 09, the counter T2 for measuring the time for carrying out the detection when the negative pressure is held is initialized to the initial value 0.

Next, the process proceeds to step S210, and the counter T2 is incremented. Next, step S211.
Then, it is determined whether the measured fuel tank internal pressure PTNK exceeds a predetermined negative pressure PREF2. This predetermined negative pressure P
For example, a value of about -10 mmHg is set as REF2. Steps S210 and S211 are repeated until the fuel tank internal pressure PTNK exceeds the predetermined negative pressure PREF2, and the time until the negative pressure PREF2 exceeds the predetermined negative pressure PREF2 is counted by the counter T.
Counted as 2. When the determination condition of step S211 is satisfied, the counting of the counter T2 is stopped and the counter value T2 is stored (time t03 in FIG. 6).

Next, in step S212, the canister closing valve 37 is opened and the canister 30 of the present system is brought into the atmosphere-introducable state (time t04 in FIG. 6).

Next, in order to detect whether or not an abnormality such as a fuel gas leak has occurred using the counter values T1 and T2 of the fuel tank internal pressure PTNK measured as described above, the process proceeds to step S213, and the negative pressure is applied. The time ratio TCHK between the time T1 until reaching a predetermined negative pressure at the time of introduction and the time T2 until reaching a predetermined negative pressure at the time of holding the negative pressure is calculated by the following equation (2).

[0046]

## EQU00002 ## TCHK = T2 / T1 (2) Then, the process proceeds to step S214, where the time ratio TCHK calculated in step S213 exceeds the determination value TREF for detecting an abnormality such as fuel gas leakage. Is determined. When the determination condition of step S214 is satisfied, the process proceeds to step S215, it is determined that there is an abnormality such as fuel gas leakage, the abnormality flag is turned on (set), and this routine is ended. On the other hand, the determination condition of step S214 is not satisfied,
When the time ratio TCHK is less than or equal to the determination value TREF, the process proceeds to step S216, it is determined that there is no abnormality such as fuel gas leakage, the abnormality flag is turned off (cleared), and this routine ends.

Incidentally, step S in the above-mentioned routine.
The relationship between the denominator and the numerator in the calculation of the time ratio TCHK of 213 may be reversed. However, in that case, step S
It goes without saying that the judgment value TREF of 214 and the direction of the inequality sign need to be changed.

FIG. 4 shows the time ratio TCHK and the judgment value T used in the abnormality detecting device for the fuel evaporation prevention mechanism according to this embodiment.
FIG. 6 is a characteristic diagram showing the relationship with REF using the fuel amount [%] in the fuel tank 22 as a parameter.

As shown in FIG. 4, the time ratio TCHK is 0 when there is no fuel gas leakage in the fuel transpiration prevention mechanism, and increases as the leakage diameter changes from φ1.0 to φ2.0, but the fuel amount increases. The value is almost the same regardless of. Therefore, in order to detect the abnormality of the fuel gas leakage of the diameter φ1.0 or more, the judgment value TREF is set to a value slightly smaller than the time ratio TCHK for the leakage diameter φ1.0 (in consideration of the influence of variations).
It turns out that you should set.

As described above, the abnormality detecting apparatus for the fuel evaporation prevention mechanism of the present embodiment includes the communication pipe 28 that connects the fuel tank 22 and the intake pipe 2 of the internal combustion engine 3 and the purge passage formed of the supply pipes 38 and 42. The adsorbent 34 of the canister 30 provided midway adsorbs the fuel gas generated in the fuel tank 22 at any time, and the purge control valve 40 is opened / closed according to the operating state of the internal combustion engine 3 to adsorb the adsorbed fuel. The fuel vaporization preventing mechanism for appropriately introducing gas into the intake pipe 2 to prevent fuel vaporization, the pressure detecting means including the pressure sensor 44 for detecting the pressure state in the fuel vaporization preventing mechanism, and the canister 30 are provided. Atmosphere hole closing means including a canister closing valve 37 capable of closing the air hole 36, and a predetermined opening / closing control for the purge control valve 40 and the atmosphere hole closing means. First time measuring means achieved by the CPU 52 in the ECU 50 for measuring the time T1 of the pressure change detected by the pressure detecting means when the negative pressure is introduced from the trachea 2 to the fuel evaporation preventing mechanism, and the purge control valve. 40
Also, the ECU 50 that measures the time T2 of the pressure change detected by the pressure detecting means when the negative pressure of the fuel vaporization prevention mechanism is maintained in association with the predetermined opening / closing control of the atmosphere hole closing means.
Second time measuring means achieved by the CPU 52 in the
CPU5 in ECU50 which detects abnormality of the fuel evaporation prevention mechanism based on each time T1, T2 measured by the 1st time measurement means and the 2nd time measurement means.
2 is provided with the abnormality detecting means.

Therefore, the adsorbent 34 of the canister 30 to which the fuel gas generated in the fuel tank 22 is adsorbed at any time
From the purge control valve 4 depending on the operating state of the internal combustion engine 3.
A fuel transpiration prevention mechanism which is appropriately introduced into the intake pipe 2 via 0 to prevent fuel transpiration, and is a purge control valve 40 and an atmosphere hole closing means in the CPU 52 in the ECU 50 as the first time measuring means. The time T1 of the pressure change when the negative pressure is introduced from the intake pipe 2 to the fuel vaporization prevention mechanism by the predetermined opening / closing control of the canister closing valve 37 is measured, and the CP in the ECU 50 as the second time measuring means is measured.
At U52, the time T2 of pressure change when the negative pressure of the fuel evaporation prevention mechanism is maintained due to the predetermined opening / closing control of the purge control valve 40 and the canister closing valve 37 is measured, and the CPU 52 in the ECU 50 as the abnormality detecting means measures the time T1. , T2, the abnormality of the fuel evaporation prevention mechanism is detected. As a result, when an abnormality such as a fuel gas leak of the fuel evaporation prevention mechanism is detected, a change in the operating state and the purge control valve 4
0 and the canister closing valve 37 itself are not affected by variations and the calculation is simplified, so that the detection accuracy is improved.

Further, in the abnormality detecting apparatus for the fuel evaporation preventing mechanism of the present embodiment, the abnormality detecting means achieved by the CPU 52 in the ECU 50 uses the ratio or the quotient in the calculation of the abnormality detecting of the fuel evaporation preventing mechanism. is there. Therefore, since the CPU 52 in the ECU 50 as the abnormality detecting means is not affected by the size of the space volume by using the ratio or the quotient for the calculation, the accuracy of the abnormality detection of the fuel evaporation prevention mechanism is improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an abnormality detection device for a fuel evaporation prevention mechanism according to a first example of an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure of abnormality detection in a CPU in the ECU used in the abnormality detection device for a fuel evaporation prevention mechanism according to the first example of the embodiment of the present invention.

FIG. 3 is a time chart corresponding to the abnormality detection routine of FIG.

FIG. 4 shows the relationship between the area ratio (time ratio) and the determination value used in the abnormality detection device for a fuel evaporation prevention mechanism according to the first example and the second example of the embodiment of the present invention. It is a characteristic view which shows quantity as a parameter.

FIG. 5 is a flowchart showing a procedure of abnormality detection in the CPU in the ECU used in the abnormality detection device for the fuel evaporation prevention mechanism according to the second example of the embodiment of the present invention.

FIG. 6 is a time chart corresponding to the abnormality detection routine of FIG.

[Explanation of symbols]

 2 intake pipe 3 internal combustion engine 8 throttle valve 22 fuel tank 28 communication pipe 30 canister 34 adsorbent 36 atmosphere hole 37 canister closing valve 38, 42 supply pipe 40 purge control valve 44 pressure sensor 50 ECU (electronic control unit) 52 CPU

Claims (3)

[Claims] 1. A fuel gas generated in the fuel tank is adsorbed at any time by an adsorbent of a canister provided in the middle of a purge passage that connects a fuel tank and an intake pipe of the internal combustion engine, and the operating state of the internal combustion engine A purge control valve is opened / closed according to the above conditions to appropriately introduce the adsorbed fuel gas into the intake pipe to prevent fuel evaporation, and a pressure state in the fuel evaporation prevention mechanism is detected. Pressure detecting means, atmosphere hole closing means for closing the air hole provided in the canister, and the intake pipe to the fuel evaporation preventing mechanism associated with predetermined opening / closing control of the purge control valve and the air hole closing means. First integrated value calculation means for calculating an integrated value of the pressure change detected by the pressure detection means at the time of introducing the negative pressure of the purge control valve and the air hole closure Second integrated value calculation means for calculating an integrated value of the pressure change detected by the pressure detection means when the negative pressure of the fuel transpiration prevention mechanism is held in accordance with a predetermined opening / closing control for the means, and the first integrated value calculation Means and an abnormality detecting means for detecting an abnormality of the fuel evaporation prevention mechanism based on each integrated value calculated by the second integrated value calculating means. . 2. A fuel gas generated in the fuel tank is adsorbed at any time by an adsorbent of a canister provided in the middle of a purge passage that connects the fuel tank and an intake pipe of the internal combustion engine, and the operating state of the internal combustion engine A purge control valve is opened / closed according to the above conditions to appropriately introduce the adsorbed fuel gas into the intake pipe to prevent fuel evaporation, and a pressure state in the fuel evaporation prevention mechanism is detected. Pressure detecting means, atmosphere hole closing means for closing air holes provided in the canister, and from the intake pipe to the fuel evaporation prevention mechanism associated with predetermined opening / closing control of the purge control valve and the air hole closing means. First time measuring means for measuring the time of the pressure change detected by the pressure detecting means when the negative pressure is introduced, the purge control valve and the air hole closing hand Second time measuring means for measuring the time of the pressure change detected by the pressure detecting means when the negative pressure of the fuel evaporation preventing mechanism is held in accordance with the predetermined opening / closing control for the first time measuring means and the first time measuring means. 2. An abnormality detection device for a fuel evaporation prevention mechanism, comprising: an abnormality detection means for detecting an abnormality of the fuel evaporation prevention mechanism based on the respective times measured by the time measurement means. 3. The fuel transpiration prevention mechanism according to claim 1, wherein the abnormality detection means uses a ratio or a quotient in the calculation for detecting an abnormality of the fuel transpiration prevention mechanism. Anomaly detection device.