JP3627879B2 - Evaporative fuel supply device failure detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a failure detection device for an evaporated fuel supply device.
[0002]
[Prior art]
Conventionally, in order to prevent the evaporated fuel generated in the fuel tank or the like from being released into the atmosphere, the evaporated fuel is introduced into the intake system (hereinafter referred to as purging) and evaporated for combustion treatment in the combustion chamber. In an engine equipped with a fuel supply device, various failure detection devices have been proposed for early detection of problems such as clogging and leakage occurring in a purge passage for introducing evaporated fuel into an intake passage.
[0003]
As a conventional example related to the failure detection technique of the evaporated fuel supply apparatus, Japanese Patent Laid-Open No. 5-256214 discloses that a negative pressure in the intake passage is applied to the fuel tank, and the purge is performed according to the rate of decrease in the fuel tank internal pressure at this time. In response to failure detection in which passage clogging is determined and fuel evaporated in the fuel tank is not released into the intake passage or the atmosphere, and the leak in the purge passage is determined by the rising speed of the fuel tank internal pressure. In addition, there is disclosed a failure detection device for an evaporative fuel supply device that can perform accurate failure determination even in a situation where a large amount of evaporated fuel is generated in the fuel tank by changing a threshold value such as failure determination time. .
[0004]
[Problems to be solved by the invention]
However, in the above-described prior art, the failure determination operation is started when the ignition switch is turned on, and thereafter, the determination operation is repeatedly executed until failure is always determined until the ignition switch is turned off. Therefore, the load required for calculating the fuel tank internal pressure drop speed, the rising speed, etc., or for determining whether or not it is in the determination region increases, and the failure determination operation may not be executed reliably.
[0005]
Further, during the failure determination operation, a constant negative pressure is always generated in the fuel tank. Due to the action of this negative pressure, a load is applied to the fuel tank from the inside, and there is a risk of deformation of the tank.
[0006]
The present invention has been made in view of such a problem, and an object of the present invention is to provide an evaporative fuel supply capable of reliably executing a failure determination operation by reducing the number of failure determination operations and reducing a load on the fuel tank. An apparatus for detecting a failure of an apparatus is provided.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the object, a failure detection apparatus for an evaporated fuel supply apparatus according to the present invention has the following features. That is,
Evaporated fuel generated from the fuel tank is collected and adsorbed by an adsorbing means, and this adsorbed evaporated fuel is put into the intake passage through a purge passage communicating the fuel tank and the intake passage of the engine during a predetermined operation. A failure detection device for detecting a failure of a fuel vapor supply device to be supplied,
A negative pressure generating means for applying a negative pressure in the intake passage to the evaporated fuel supply passage that communicates from the fuel tank to the intake passage through the purge passage when a predetermined failure diagnosis condition is satisfied;
Negative pressure detecting means for detecting negative pressure acting on the fuel tank;
An abnormality determining means for determining an abnormal state of the evaporated fuel supply passage based on the detection result of the negative pressure;
A prohibiting means for prohibiting determination by the abnormality determining means for a predetermined period after determining the abnormal state ;
The prohibiting unit prohibits the determination by the abnormality determining unit during the predetermined period after the abnormal state of the fuel vapor supply passage is determined and before the predetermined travel distance is reached .
[0008]
As described above, in the failure detection device for the evaporated fuel supply device of the present invention, when a predetermined failure diagnosis condition is satisfied, the evaporated fuel supply passage that leads from the fuel tank to the intake passage through the purge passage is connected to the intake passage. The negative pressure acting on the fuel tank is detected, and the abnormal state of the evaporated fuel supply passage is determined based on the detection result of the negative pressure. Further, after the abnormal state is determined , It acts to prohibit the determination of a predetermined period until it becomes longer than the travel distance .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0010]
<Configuration of evaporative fuel supply device>
First, the configuration of the evaporated fuel supply device according to the present embodiment will be described. FIG. 1 is a diagram showing an overall configuration of a fuel vapor supply apparatus according to an embodiment of the present invention.
[0011]
In FIG. 1, reference numeral 1 denotes an engine. The engine 1 includes a cylinder block 3 having a cylinder 2, a cylinder head 4 assembled on the upper surface of the cylinder block 3, and a cylinder head cover 5 assembled on the upper surface of the cylinder head 4. And a piston 6 that reciprocates in the cylinder 2, and a combustion chamber 7 defined by the lower surface of the cylinder head 4 and the top surface of the piston 6 is formed in the cylinder 2. The piston 6 is connected to the crankshaft 8 via a connecting rod (not shown). Further, the cylinder head 4 is formed with an intake port 4a and an exhaust port 4b. 1 is an intake passage for supplying intake air into the combustion chamber 7, and 10 is an intake valve for opening and closing the downstream end opening of the intake port 4a. 11 is an exhaust passage for exhausting exhaust gas in the combustion chamber 7, 12 is an exhaust valve for opening and closing the upstream end opening of the exhaust port 4 b, and 13 is a catalyst as an exhaust purification device disposed in the middle of the exhaust passage 11. It is a converter.
[0012]
An air flow meter 14 for detecting the intake air amount, a slot valve 15 for controlling the intake air amount, a surge tank 16 for absorbing intake pulsation and the like, and an injector 17 for injecting and supplying fuel to the intake passage 9 in order from the upstream side. The upstream end of the intake passage 9 is connected to an air cleaner 18. A part of the intake passage 9 on the downstream side of the surge tank 16 is branched into a primary passage 9a and a secondary passage 9b. The secondary passage 9b is opened and closed by an actuator 9c that operates according to the internal pressure of the surge tank 16. A secondary valve 9d is provided.
[0013]
Reference numeral 19 denotes a bypass passage that bypasses the throttle valve 15 and supplies air to the combustion chamber 7. In the middle of the bypass passage 19, the amount of air flowing through the bypass passage 19 is controlled when the engine 1 is idling to control the engine speed (idle rotation). An idle speed control valve (ISC valve) 20 comprising a proportional solenoid valve for adjusting the number) is provided.
[0014]
Reference numeral 21 denotes a fuel tank connected to the injector 17 via a fuel supply passage 22. A fuel pump 22 a is connected to the upstream end of the fuel supply passage 22, and a fuel filter 22 b is interposed in the fuel supply passage 22. The injector 17 is connected to a regulator passage 23 having a pressure regulator 23a for keeping the internal pressure of the injector 17 constant and performing stable fuel injection.
[0015]
The engine 1 includes an evaporated fuel supply device 25 that supplies evaporated fuel generated in the fuel tank 21 to the combustion chamber 7 side. Hereinafter, the evaporated fuel supply device 25 will be described. The evaporated fuel supply device 25 includes a purge passage 26, and the purge passage 26 has an upstream end opened at an upper portion in the fuel tank 21, and a downstream end opened at the intake passage 9 by the surge tank 16. In the middle of the purge passage 26, in order from the upstream side (fuel tank 21 side), a separator 26a for separating the liquid fuel from the evaporated fuel, a 2-way valve 26b, and an evaporated fuel adsorbing means for recovering and adsorbing the evaporated fuel. A purge control valve 28 is provided as a purge adjusting means including a canister 27 and a duty solenoid valve that opens and closes the purge passage 26 to adjust the supply (purge) of the evaporated fuel to the intake passage 9. The separator 26 a is connected to the fuel tank 21 via a fuel return passage 26 c for returning the separated liquid fuel to the fuel tank 21. An air release passage 29 is connected to the canister 27. The air release passage 29 is generally open into the internal space of the canister 27, and the other ends thereof are opened to the outside air. When the evaporated fuel is fed into the intake passage 9, the outside air is discharged along with the opening operation of the purge control valve 28. On the other hand, when the evaporated fuel overflows in the canister 27, a part of the evaporated fuel is released into the atmosphere. Further, an air release valve 29 a is disposed in the middle of the air release passage 29. The air release valve 29a is closed only when a later-described failure determination (determination of purge passage clogging or leakage) of the evaporated fuel supply device 25 is performed, and is always open in other states. ing. Thereby, the atmosphere release means is constituted by the atmosphere release passage 29 and the atmosphere release valve 29a.
[0016]
Further, reference numeral 30 in FIG. 1 denotes an EGR device which includes an EGR passage 31 and an EGR control valve 32 interposed in the EGR passage 31, and is a throttle valve detected by a booth and a pressure detection passage 32a. The supply amount of EGR gas is set according to the pressure difference between the negative pressure on the downstream side and the negative pressure on the upstream side of the throttle valve detected by the atmospheric pressure detection passage 32b.
[0017]
The injector 17, the idle speed control valve 20, the purge control valve 28, the air release valve 29a and the like are controlled by a control unit 40 having a built-in CPU. The control unit 40 includes a detection signal from a throttle sensor 33 for detecting the opening degree of the throttle valve 15, a detection signal from a crank angle sensor 34 for detecting a crank angle of the crankshaft 8, and a detection signal from a vehicle speed sensor 35 for detecting a vehicle speed. The detection signal of the tank pressure detection sensor 36 for detecting the pressure in the fuel tank 21, the detection signal of the alcohol sensor 37 for detecting a certain call concentration of the fuel stored in the fuel tank 21, etc. are input. ing. The alcohol sensor 37 is an optical alcohol sensor or the like. Further, a purge failure warning lamp (MIL) 38 is disposed in the vehicle interior, and the control unit 40 can output a signal to the purge failure warning lamp 38. The tank internal pressure detection sensor 36 and the alcohol sensor 37 constitute tank pressure detection means.
[0018]
<Configuration of failure detection device>
Next, the configuration of the failure detection apparatus for the evaporated fuel supply apparatus according to this embodiment will be described. FIG. 2 is a diagram showing the configuration of the failure detection apparatus for the evaporated fuel supply apparatus according to the embodiment of the present invention.
[0019]
In FIG. 2, the failure detection apparatus 100 of the present embodiment generates a negative pressure in the fuel tank 21 and the purge passage 26 by controlling opening and closing of the purge control valve 28 and the atmosphere release valve 29a, and also generates this negative pressure. In this state, the detection signal of the tank pressure detecting means 42 for detecting the negative pressure in the fuel tank 21 by the tank pressure detecting sensor 36 is received to detect clogging or leakage of the pressure purge passage 26 or failure of the purge control valve 28 or the like. The failure determination unit 41 that performs the determination of the failure of the evaporated fuel supply device 25 is performed. The outline of this failure determination will be described. First, the purge control valve 28 is opened and the atmosphere release valve 29a is closed to apply the negative pressure of the intake passage 9 to the fuel tank 21. In this state, when the engine 1 is in a predetermined running state, the change in the internal pressure of the fuel tank 21 is detected by the tank pressure detection sensor 36, and the purge passage 26 is clogged when the rate of decrease in the internal pressure of the fuel tank 21 is slow. I am trying to determine what I am doing. On the other hand, if the purge passage 26 is not clogged in this clogging determination operation, the purge control valve 28 and the air release valve 29a are both closed from the state in which the negative pressure is applied in the fuel tank 21. The fuel evaporated in the tank 21 is prevented from being released into the intake passage 9 and the atmosphere. Then, the change in the internal pressure of the fuel tank 21 at this time is detected by the tank pressure detection sensor 36, and the purge passage when the rising speed of the internal pressure of the fuel tank 21 is fast (when the tank internal pressure is fast and returns to the atmospheric pressure side). 26, it is determined that leakage or a failure has occurred in the purge control valve 28 or the like.
[0020]
<Failure judgment operation>
Next, the failure detection operation of the evaporated fuel supply apparatus according to this embodiment will be described.
(First embodiment)
3 to 5 are flowcharts showing a failure detection operation of the evaporated fuel supply apparatus according to the first embodiment of the present invention. FIG. 6A is a time chart showing operation timings of the purge control valve, the 2-way valve, and the air release valve of the evaporated fuel supply device, and FIG. 6B is the timing chart shown in FIG. It is a figure which shows the change of the fuel tank internal pressure in the operation timing of each valve | bulb. Below, the signal processing procedure by the control unit 40 which performs the failure determination operation | movement of the evaporative fuel supply apparatus 25 is demonstrated.
[0021]
In FIG. 3, first, in step S2, the process is started in response to the ON signal of the ignition switch, and the flag F is reset in step S4. This flag F indicates whether or not a predetermined negative pressure has been generated in the fuel tank at least once by a failure determination operation after turning on the ignition switch in a step described later. Thereafter, in step S6, it is determined whether or not the flag F is 1, that is, whether or not a predetermined negative pressure is generated in the fuel tank and the failure determination operation has been executed at least once. If executed once (Yes in step S6), this program is terminated, and the flag F is 0, that is, the failure determination operation has not been executed once after the ignition switch is turned on (No in step S6). Proceed to step S10.
[0022]
In step S10, it is determined whether or not the internal pressure FTP of the fuel tank is smaller than −400 mmAg. In step S10, if the internal pressure FTP of the fuel tank is smaller than -400 mmAg (Yes in step S10), the tank internal pressure FTP is too low, and it is determined that an abnormality such as clogging has occurred in the purge passage 26 and the process proceeds to step S44 described later. When the internal pressure FTP of the fuel tank is larger than −400 mmAg (No in step S10), the process proceeds to step S12.
[0023]
In step S12, after turning on the ignition switch, it is determined whether or not the engine 1 is in a predetermined travel region. In step S12, if the engine 1 is not in the predetermined travel area (No in step S12), the process returns to step S6 described above. If the engine 1 is in the predetermined travel area (Yes in step S12), the process proceeds to step S14. In step S14, in order to generate a negative pressure in the fuel tank, the air release valve 29a (hereinafter abbreviated as CDCV) is closed, the 2-way valve 26b (hereinafter abbreviated as TPCV), and the purge control valve 28. (Hereinafter abbreviated as PCV) is opened. Thereafter, in step S16, it is determined whether or not the internal pressure FTP of the fuel tank is smaller than -200 mmAg. In step S16, if the internal pressure FTP of the fuel tank is smaller than -200 mmAg (Yes in step S16), the process proceeds to step S20. If the internal pressure FTP of the fuel tank is larger than -200 mmAg (No in step S16), the process proceeds to step S18. In step S18, it is determined whether or not a predetermined time t1 (for example, t1 = 25 seconds) has elapsed in the state of step S14. If the predetermined time t1 has elapsed (Yes in step S18), the process proceeds to step S20, and the predetermined time t1 has elapsed. If not (No in step S18), the process returns to step S12, and the processes in steps S12 to S16 are executed again.
[0024]
In step S20, the flag F is set to 1 on the assumption that a predetermined negative pressure is generated in the fuel tank in steps S16 to S18. Thereafter, in step S22, the purge control by the evaporated fuel supply device 25 is stopped and the PCV is closed.
[0025]
As shown in FIG. 4, in step S24 subsequent to step S22, after waiting for a predetermined time t2 (for example, t2 = 1 second) with purge control stopped, in step S26, the internal pressure FTP of the fuel tank Is detected. Thereafter, in step S28, it is determined whether or not the internal pressure FTP of the fuel tank is smaller than -130 mmAg. In step S28, if the internal pressure FTP of the fuel tank is larger than -130 mmAg (No in step S28), the tank internal pressure FTP is too high even though a predetermined negative pressure is applied, so that the purge passage 26 is leaked or released to the atmosphere. If it is determined that an abnormality has occurred in the valve or the like, the process proceeds to step S44 described later. If the internal pressure FTP of the fuel tank is smaller than -130 mmAg (Yes in step S28), the process proceeds to step S30. In step S30, it is determined whether or not the absolute value of the difference between the internal pressure FTP of the fuel tank and the predetermined value FTP1 is smaller than 110 mmAg. In step S30, if the absolute value of the difference between the internal pressure FTP of the fuel tank and the predetermined value FTP1 is larger than 110 mmAg (No in step S30), the tank internal pressure FTP is too high, so that the purge passage 26 leaks and the air release valve is abnormal. When the absolute value of the difference between the internal pressure FTP of the fuel tank and the predetermined value FTP1 is smaller than 110 mmAg (Yes in step S30), the predetermined time t3 (for example, , T3 = 30 seconds), the process in step S30 is repeated, and after a predetermined time t3, the process proceeds to step S34.
[0026]
In step S34, in order to release the fuel tank internal pressure FTP to the atmosphere, CDCV and PCV are opened, and TPCV is closed. Thereafter, in step S36, after waiting for a predetermined time t4 (for example, t4 = 3 seconds) with the internal pressure of the fuel tank released to the atmosphere, in step S38, the internal pressure FTP of the fuel tank is detected.
[0027]
As shown in FIG. 5, in step S40 following step S38, it is determined whether or not the absolute value of the difference between the internal pressure FTP of the fuel tank and the predetermined value FTP2 is greater than 5 mmAg. In step S40, if the absolute value of the difference between the internal pressure FTP of the fuel tank and the predetermined value FTP2 is larger than 5 mmAg (Yes in step S40), it is determined that the tank internal pressure FTP is normal, and the process returns to the above-described step S6. When the absolute value of the difference between the internal pressure FTP and the predetermined value FTP2 is smaller than 5 mmAg (No in step S40), the process proceeds to step S44.
[0028]
In step S44, since the internal pressure FTP of the fuel tank does not return to the atmospheric release state even though the internal pressure of the fuel tank is released to the atmosphere, it is determined that the atmospheric release valve is abnormal or the purge passage 26 is clogged. The lamp 38 is turned on to warn the driver of the failure of the evaporated fuel supply device 25. Thereafter, in step S46, the failure code when it is determined to be abnormal is stored and used for maintenance or the like at the time of repair at a later date.
[0029]
Next, changes in the internal pressure of the fuel tank at the operation timing of each valve will be described with reference to FIGS.
[0030]
3 to 6, in step S14, in order to generate a negative pressure in the fuel tank, the CDCV is closed, the TPCV and the PCV are opened, and the purge control is performed after a predetermined negative pressure or a predetermined time has elapsed. By stopping and closing the PCV, the fuel tank internal pressure FTP is lowered to P1 during the elapse of the predetermined time t1 (P1 <−200 mmAg). After that, in step S24, it is determined how much the fuel tank internal pressure FTP changes from the state of the negative pressure P1 during the elapse of the predetermined time t2 (P1 → P2). It is determined that there is an abnormality such as leakage in CDCV or PCV. Further, after a predetermined time t3 has elapsed, the CDCV and PCV are opened, and the TPCV is closed to release the atmosphere, and then whether or not the fuel tank internal pressure FTP is changed from the negative pressure P2 state to the atmospheric release state P0. If it is not open to the atmosphere, it is determined that the purge passage 26 is clogged or that there is an abnormal operation in the CDCV or TPCV.
[0031]
In the above first embodiment described, after the ignition switch ON, by the failure detection count of the evaporative fuel supply apparatus Ru generate a negative pressure in the fuel tank was reduced as compared with the conventional reliably perform failure determination operation The load on the fuel tank can be reduced.
[0032]
(Second Embodiment)
Next, a failure detection operation of the evaporated fuel supply device according to the second embodiment will be described. FIG. 7 is a flowchart showing a failure detection operation of the evaporated fuel supply apparatus according to the second embodiment of the present invention.
[0033]
The failure detection of the evaporated fuel supply device according to the second embodiment is performed in step S2 with a predetermined travel distance (for example, after a predetermined negative pressure is applied to the fuel tank for failure detection in the state where the ignition switch is turned on. , 200 to 300 km) is an embodiment in which failure detection is prohibited. In the following, description of processing steps common to the above-described first embodiment will be omitted by assigning the same step numbers, and only different processing steps will be described.
[0034]
In FIG. 7, first, if the determination in step S40 is Yes, the process proceeds to step S50, and after the flag F is set to 1, that is, after a predetermined negative pressure is applied to the fuel tank for failure detection, It is determined whether or not a travel distance (for example, 200 to 300 km) has been reached. If the predetermined travel distance has not been reached in step S50 (No in step S50), the process returns to step S6. If the predetermined travel distance has been reached (Yes in step S50), the process returns to step S4. If the flag F is 1 in step S6, that is, if the failure determination operation is executed at least once after the ignition switch is turned on (Yes in step S6), the process proceeds to step S50. Furthermore, in step S12, when the engine 1 is not in the predetermined travel region (No in step S12), the process returns to step S6.
[0035]
In the failure detection operation of the evaporated fuel supply device in the second embodiment described above, in addition to the effects of the first embodiment, failure detection is performed after the predetermined travel distance, so failure detection after the ignition switch is turned on is detected. It is possible to improve the detection accuracy by securing the number of times.
[0036]
(Third embodiment)
Next, a failure detection operation of the evaporated fuel supply device according to the third embodiment will be described. FIG. 8 is a flowchart showing a failure detection operation of the evaporated fuel supply apparatus according to the third embodiment of the present invention.
[0037]
The failure detection of the evaporated fuel supply device according to the third embodiment is performed in a state in which a predetermined negative pressure is applied to the fuel tank for the failure detection in the state where the ignition switch is turned on in step S2 (for example, This is an embodiment in which failure detection is prohibited until it reaches 2 to 3 hours). In the following, description of processing steps common to the above-described first embodiment will be omitted by assigning the same step numbers, and only different processing steps will be described.
[0038]
In FIG. 8, first, if the determination in step S40 is Yes, the process proceeds to step S52, and after the flag F is set to 1, that is, after a predetermined negative pressure is applied to the fuel tank for failure detection, It is determined whether time t5 (for example, 2-3 hours) has elapsed. If the predetermined time t5 has not elapsed in step S52 (No in step S52), the process returns to step S6, and if the predetermined time t5 has elapsed (Yes in step S52), the process returns to step S4. If the flag F is 1 in step S6, that is, if the failure determination operation is executed at least once after the ignition switch is turned on (Yes in step S6), the process proceeds to step S52. Furthermore, in step S12, when the engine 1 is not in the predetermined travel region (No in step S12), the process returns to step S6.
[0039]
In the failure detection operation of the evaporated fuel supply device in the third embodiment described above, in addition to the effect of the first embodiment, failure detection is executed after the predetermined time t5 has elapsed, so failure after the ignition switch is turned on. The detection accuracy can be improved by securing the number of detections.
[0040]
Note that the present invention can be applied to a modified or changed embodiment without departing from the spirit of the present invention.
[0041]
For example, it goes without saying that the predetermined times t1 to t4 and the determination threshold value of the fuel tank internal pressure in the failure detection operation of the first embodiment can be arbitrarily set.
[0042]
Needless to say, the travel distance (for example, 200 to 300 km) and the predetermined time t5 (for example, 2 to 3 hours) after the ignition switch is turned on in the second and third embodiments can be arbitrarily set.
[0043]
In the present embodiment, the control procedure for executing the failure determination operation once after the ignition switch is turned on until it is turned off has been described. Of course, the failure determination operation may be executed a plurality of times.
[0044]
【The invention's effect】
As described above, in the failure detection device for the evaporated fuel supply device of the present invention, when a predetermined failure diagnosis condition is satisfied, the evaporated fuel supply passage that leads from the fuel tank to the intake passage through the purge passage is connected to the intake passage. The negative pressure acting on the fuel tank is detected, and the abnormal state of the evaporated fuel supply passage is determined based on the detection result of the negative pressure. Further, after the abnormal state is determined , Since determination for a predetermined period until the travel distance is exceeded is prohibited, the failure determination operation can be reliably executed by reducing the number of failure determination operations, and the load on the fuel tank can be reduced.
[0045]
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a fuel vapor supply apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of a failure detection device for an evaporated fuel supply device according to an embodiment of the present invention.
FIG. 3 is a diagram showing a failure detection operation of the evaporated fuel supply apparatus according to the first embodiment of the present invention.
FIG. 4 is a diagram showing a failure detection operation of the evaporated fuel supply apparatus according to the first embodiment of the present invention.
FIG. 5 is a diagram showing a failure detection operation of the evaporated fuel supply apparatus according to the first embodiment of the present invention.
6A is a time chart showing operation timings of a purge control valve, a 2-way valve, and an air release valve of the evaporated fuel supply device, and FIG. 6B is an operation of each valve shown in FIG. It is a figure which shows the change of the fuel tank internal pressure in timing.
FIG. 7 is a diagram illustrating a failure detection operation of the evaporated fuel supply device according to the second embodiment of the present invention.
FIG. 8 is a diagram showing a failure detection operation of the evaporated fuel supply device according to a third embodiment of the present invention.
[Explanation of symbols]
9 ... Intake passage 21 ... Fuel tank 26 ... Purge passage 27 ... Canister 28 ... Purge control valve 29 ... Air release passage 29a ... Air release valve 36 ... Tank pressure detection sensor

Claims (1)

Evaporated fuel generated from the fuel tank is collected and adsorbed by an adsorbing means, and this adsorbed evaporated fuel is put into the intake passage through a purge passage communicating the fuel tank and the intake passage of the engine during a predetermined operation. A failure detection device for detecting a failure of a fuel vapor supply device to be supplied,
A negative pressure generating means for applying a negative pressure in the intake passage to the evaporated fuel supply passage that communicates from the fuel tank to the intake passage through the purge passage when a predetermined failure diagnosis condition is satisfied;
Negative pressure detecting means for detecting negative pressure acting on the fuel tank;
An abnormality determining means for determining an abnormal state of the evaporated fuel supply passage based on the detection result of the negative pressure;
A prohibiting means for prohibiting determination by the abnormality determining means for a predetermined period after determining the abnormal state ;
The said prohibiting means prohibits the determination by the said abnormality determination means during the said predetermined period after determining the abnormal state of the said evaporative fuel supply passage until it becomes more than a predetermined travel distance. Failure detection device.

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