JP3204150B2 - Failure diagnosis device for fuel vapor processing unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor processing apparatus which collects and processes fuel vapor generated in a fuel tank without releasing it into the atmosphere. More specifically, the present invention relates to a fuel vapor processing apparatus including a canister for collecting fuel vapor and a means for appropriately purging the fuel collected by the canister into an intake passage of an engine. The present invention relates to a failure diagnostic device for diagnosing airtightness on the side.

[0002]

2. Description of the Related Art Conventionally, as one of devices mounted on a vehicle or the like, there is a fuel vapor processing device which collects and processes fuel vapor generated in a fuel tank without releasing it to the atmosphere. is there. As shown in FIG. 11, this type of device has a canister 73 for collecting fuel vapor generated in a fuel tank 71 through a vapor line 72. The canister 73 contains an adsorbent 74 made of activated carbon or the like, and a purge line 75 extending from the canister 73 communicates with an intake passage 77 of an engine 76. Canister 7
3 temporarily adsorbs the fuel vapor introduced from the vapor line 72 to the adsorbent 74. Further, the canister 73 collects only the fuel, and then discharges only the gas containing no fuel component, particularly, hydrocarbon (HC) from the communication hole 78 to the outside. Further, during operation of the engine 76, the canister 73 collects the once collected fuel through the purge line 75 to the intake passage 7.
Purge to 7. Then, a purge control valve 79 provided in the purge line 75 adjusts the amount of fuel passing through the purge line 75 according to the necessity of the engine 76.

In the case of this type of processing apparatus, if a failure such as the vapor line 72 is broken for some reason or the piping is disconnected, the airtightness inside the processing apparatus is reduced. There is a risk. As a result, the fuel vapor may not be properly treated as intended.

Therefore, in recent years, Japanese Patent Application Laid-Open No. 6-10893 discloses an apparatus for diagnosing the above-mentioned failure.
No. 0 is known. As shown in FIG. 12, the fuel vapor processing apparatus targeted by the failure diagnosis apparatus includes a fuel tank 81, a canister 82, a vapor line 83, a purge line 84, and the like. The purge line 84 connects the canister 82 and the intake passage 80. A purge VSV (purge control valve) 85 provided in the middle of the purge line 84 is controlled and opened by an electronic control unit (ECU) 86 during operation of the engine. Further, a vapor control valve (internal pressure control valve) 87 provided in the middle of the vapor line 83 regulates the flow of fuel vapor from the fuel tank 81 to the canister 82. This control valve 87 comprises a check valve including a check ball,
It is opened based on the difference between the internal pressure on the fuel tank 81 side and the internal pressure on the canister 82 side. When the control valve 87 is opened, the fuel tank 81 is moved from the canister 82.
The flow of fuel vapor into the fuel is allowed.

[0005] The vapor control valve 8 is connected to the vapor line 83.
Another control valve 90 provided in a passage bypassing the EC 7
Controlled by U86. When the control valve 90 is opened while the vapor control valve 87 is closed, the fuel vapor generated in the fuel tank 81 is released from the canister 8.
Flow to 2. The diagnostic device has a pressure sensor 88 that can individually detect the internal pressure on the tank side and the internal pressure on the canister side with the vapor control valve 87 as a boundary.
That is, the three-way switching valve 89 connected to the pressure sensor 88
The other two ports are connected to a vapor line 83 (in the direction of arrow A in the figure) on the side of the fuel tank 81 and a vapor line 83 (in the direction of arrow B in the figure) on the side of the canister 82 with the vapor control valve 87 as a boundary. ing. When the ECU 86 switches the three-way switching valve 89 as necessary, the pressure sensor 88 detects the tank-side internal pressure and the canister-side internal pressure, respectively. Then, the ECU 86
Is to individually diagnose the tank-side airtightness and the canister-side airtightness based on the detected tank-side internal pressure value and canister-side internal pressure value.

Here, the basic principle for diagnosing the airtightness of the tank will be described. When fuel vapor is generated in the fuel tank 81 with the control valve 90 closed, the tank side internal pressure becomes equal to or higher than a predetermined reference value. Here, the fuel tank 8
If there is a hole or the like in the vapor line 1 or the vapor line 83, the tank-side internal pressure will be maintained at about the atmospheric pressure,
It does not rise above the reference value. Accordingly, the ECU 86 determines whether the value of the tank-side internal pressure detected by the pressure sensor 88 is equal to or higher than the reference value or whether or not the tank-side internal pressure changes to a predetermined value or more. Sex can be diagnosed.

As described above, on the fuel tank side, basically, it is determined whether or not the pressure in the fuel tank detected by the pressure sensor is equal to or higher than a predetermined reference value or the pressure in the fuel tank is equal to or higher than a predetermined value. A diagnosis of the airtightness can be made based on whether or not the airtightness changes.

[0008]

However, the above-described failure diagnosis apparatus has the following problems. That is, the vapor line 83 from the fuel tank 81 to the vapor control valve 87 or the vapor line 83
If the communication path that communicates with the three-way switching valve 89 is blocked for some reason, it is not possible to accurately detect the tank-side internal pressure. As a result, despite the presence of holes and the like in the fuel tank 81 and the vapor line 83,
There is a possibility that a diagnosis (erroneous diagnosis) of normality may be made without being able to diagnose the abnormality.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a failure diagnosis apparatus for a fuel vapor processing apparatus for diagnosing airtightness on a fuel tank side.
If the vapor passage from the fuel tank to the internal pressure control valve or the communication passage connecting the vapor passage and the three-way switching valve is blocked, it is possible to reliably determine that the communication passage is closed, and further improve the fault diagnosis. It is an object of the present invention to provide a failure diagnosis device for a fuel vapor treatment device which can be realized.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, fuel vapor from a fuel tank is supplied to an engine intake passage via a vapor passage, a canister and a purge passage. An internal pressure that is provided between a purge device for purging and the vapor passage and the canister, and that opens when the internal pressure of the fuel tank becomes equal to or higher than a predetermined pressure higher than the atmospheric pressure to maintain the internal pressure of the fuel tank at or below a predetermined pressure; A control valve, a pressure sensor for detecting the fuel tank internal pressure and the purge passage side internal pressure with the internal pressure control valve as a boundary, the pressure detected by the pressure sensor, the fuel tank internal pressure and The communication state between the fuel tank and the pressure sensor and the communication state between the purge passage and the pressure sensor are switched to switch between the pressure in the purge passage and the pressure in the purge passage. A failure valve for monitoring the fuel tank pressure after the engine is started detected by the pressure sensor and diagnosing the presence or absence of a leakage abnormality on the fuel tank side. Switching control means for switching and controlling the three-way switching valve so that the pressure detected by the sensor is in the order of the fuel tank pressure, the purge passage side pressure, and the fuel tank pressure, and the pressure passage sensor by the pressure sensor. The pressure between the fuel tank internal pressure detected by the pressure sensor before the internal pressure is detected and the fuel tank internal pressure detected by the pressure sensor after the purge passage side internal pressure is detected by the pressure sensor A closing determining unit that determines whether or not the vapor passage or the communication passage communicating between the internal pressure control valve and the three-way switching valve is closed based on the difference. It has as its gist that there was example.

According to a second aspect of the present invention, in the failure diagnosis apparatus for a fuel vapor processing apparatus according to the first aspect,
The gist of the gist is that the blockage determining means determines that the blockage is made when the pressure difference is larger than a predetermined determination value.

Further, according to the third aspect of the present invention, in the failure diagnosis apparatus for a fuel vapor processing apparatus according to the first or second aspect, the determination by the blockage determining means is performed by the pressure sensor using the pressure inside the purge passage. The gist is that the pressure detection is performed when the pressure in the fuel tank detected by the pressure sensor before the pressure is detected exceeds a predetermined pressure greater than the atmospheric pressure.

According to a fourth aspect of the present invention, in the failure diagnosis apparatus for a fuel vapor processing apparatus according to any one of the first to third aspects, the determination by the blockage determining means is performed by the pressure sensor by the pressure sensor. The gist is that the control is performed when the fuel vapor purge control is being performed during the period in which the passage-side internal pressure is detected.

(Operation) According to the first aspect of the present invention, the fuel vapor from the fuel tank is purged to the engine intake passage through the vapor passage, the canister and the purge passage by the purge device. The internal pressure control valve provided between the vapor passage and the canister opens when the internal pressure of the fuel tank exceeds a predetermined pressure higher than the atmospheric pressure to maintain the internal pressure of the fuel tank at a predetermined pressure or less. Further, the three-way switching valve switches the communication state between the fuel tank and the pressure sensor and between the purge passage and the pressure sensor. By this switching, the pressure sensor detects the fuel tank internal pressure and the purge passage side internal pressure at the internal pressure control valve. Then, the pressure inside the fuel tank after the start of the engine, which is detected by the pressure sensor, is monitored, and the presence or absence of a leakage abnormality on the fuel tank side is diagnosed.

According to the present invention, the three-way switching valve is switched by the switching control means, so that the pressure detected by the pressure sensor changes in the order of the fuel tank pressure, the purge passage side pressure, and the fuel tank pressure. Becomes The fuel tank internal pressure detected by the pressure sensor before the pressure sensor detects the purge passage-side internal pressure, and the fuel pressure detected by the pressure sensor after the purge passage-side internal pressure is detected by the pressure sensor. On the basis of the pressure difference from the pressure in the tank, the blockage determination means determines whether the vapor passage or
It is determined whether or not a communication passage communicating between the internal pressure control valve and the three-way switching valve is closed. In particular, according to the second aspect of the present invention, the blockage determining means determines that the blockage is made when the pressure difference is larger than a predetermined determination value.

If the vapor passage or the communication passage is closed for some reason, the pressure in the fuel tank after the switching of the three-way switching valve is affected by the pressure in the purge passage. Therefore, a relatively large pressure difference between the pressure in the fuel tank and the pressure in the fuel tank before the switching can occur. According to the present invention, the presence or absence of blockage can be reliably determined based on the pressure difference.

Further, according to the third aspect of the present invention,
In addition to the operation of the invention described in claims 1 and 2, the determination by the blockage determination means is that the pressure in the fuel tank detected by the pressure sensor before the pressure in the purge passage is detected by the pressure sensor. This is performed when a predetermined pressure greater than the atmospheric pressure is exceeded. For this reason, when the vapor passage or the communication passage is closed, the pressure difference between the pressures in the fuel tank before and after the switching is large. Therefore, in this case, for example, the determination value can be set relatively large, and the determination of the occlusion can be made more reliable.

In addition, according to the invention described in claim 4,
In addition to the operation of the invention described in any one of claims 1 to 3, in the determination by the blockage determination means, the purge control of the fuel vapor is performed during a period in which the pressure inside the purge passage is detected by the pressure sensor. Done if done. Again, in this case,
When the vapor passage or the communication passage is closed, the pressure difference in the fuel tank pressure before and after the switching becomes large. Therefore, it is possible to more reliably determine the occlusion.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a failure diagnosis apparatus for a fuel vapor processing apparatus according to the present invention is embodied in an automobile will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a fuel vapor processing apparatus and a failure diagnosis apparatus according to the present embodiment. A gasoline engine system mounted on an automobile 40 as a vehicle includes a fuel tank 1 for storing fuel. The fuel tank 1 is for injecting fuel into the inside, that is,
It has an inlet pipe 2 for refueling, and this pipe 2 includes a refueling port 2a at a tip. When refueling the fuel tank 1, a refueling nozzle (not shown) is inserted into the refueling port 2a. In addition, the cap 3 that closes the filler port 2a
Is removable.

A main line 5 extending from a pump 4 built in the fuel tank 1 is connected to a delivery pipe 6. A plurality of injectors 7 provided on the pipe 6
Indicates a plurality of cylinders (not shown) provided in the engine 8
It is arranged corresponding to. A return line 9 extending from the delivery pipe 6 is connected to the fuel tank 1. When the pump 4 operates, the fuel discharged from the pump 4 passes through the main line 5 and the delivery pipe 6
And is distributed to each injector 7. Then, when each injector 7 operates, fuel is injected into the intake passage 10.

The intake passage 10 includes an air cleaner 11 and a surge tank 10a, through which purified air is introduced through the air cleaner 11. An air-fuel mixture of fuel and air injected from each injector 7 is supplied to each cylinder of the engine 8 for combustion. The remaining fuel in the delivery pipe 6 without being distributed to each injector 7 returns to the fuel tank 1 through the return line 9. The exhaust gas after combustion is discharged from each cylinder of the engine 8 to the outside through the exhaust passage 12.

The fuel vapor processing apparatus according to the present embodiment collects and processes the fuel vapor generated in the fuel tank 1 without releasing it to the atmosphere. This processing apparatus has a canister 14 for collecting fuel vapor generated in the fuel tank 1 through a vapor line (which constitutes a vapor passage) 13. The canister 14 has a built-in adsorbent 15 made of activated carbon or the like, and a portion occupied by the adsorbent 15 in the canister 14 and the adsorbent 15
And spaces 14a and 14b located above and below the space 14a.

The first atmospheric control valve 16 provided on the canister 14 is a diaphragm type check valve. The control valve 16 is opened when the internal pressure of the canister 14 is smaller than the atmospheric pressure to allow the introduction of outside air (atmospheric pressure) to the canister 14 and to prevent the gas flow in the opposite direction. An air pipe 17 extending from the control valve 16 is connected near the air cleaner 11. Therefore, outside air purified by the air cleaner 11 is introduced into the canister 14. The second atmospheric control valve 18 provided on the canister 14 is a diaphragm type check valve. This control valve 1
Numeral 8 is opened when the internal pressure of the canister 14 becomes higher than the atmospheric pressure, to allow the gas (internal pressure) to be led out from the canister 14 to the outlet pipe 19, and to prevent the gas flow in the opposite direction. ing.

A vapor control valve (constituting an internal pressure control valve) 20 provided in the canister 14 controls fuel vapor flowing from the fuel tank 1 to the canister 14. The control valve 20 is composed of a diaphragm check valve, and has a built-in diaphragm-type valve element that operates by receiving pressure. The control valve 20 is based on a difference between an internal pressure (hereinafter, referred to as “tank-side internal pressure”) PT on the side of the fuel tank 1 including the vapor line 13 and an internal pressure (hereinafter, referred to as “canister-side internal pressure”) PC on the canister 14 side. The valve is opened by operating the valve. When the control valve 20 is opened, the flow of fuel vapor into the canister 14 is allowed. That is, the vapor control valve 20 opens when the canister-side internal pressure PC becomes substantially equal to the atmospheric pressure and the internal pressure PC is smaller than the tank-side internal pressure PT to allow the fuel vapor to flow into the canister 14. In addition, the vapor control valve 20
Allows the flow of gas from the canister 14 to the fuel tank 1 when the canister-side internal pressure PC is higher than the tank-side internal pressure PT.

A purge line (constituting a purge passage) 21 extending from the canister 14 is connected to a surge tank 10a.
Is in communication with The canister 14 is a vapor line 13
Only the fuel component in the fuel vapor introduced through the fuel cell is collected, and only the gas not containing the fuel component is discharged to the outside through the outlet pipe 19 when the atmospheric control valve 18 is opened. When the engine 8 is operating, the intake negative pressure generated in the intake passage 10 acts on the purge line 21 and the canister 1
4 is purged into the intake passage 10 through the purge line 21. Also, the purge line 21
The purge control valve 22 provided in the controller adjusts the amount of fuel passing through the purge line 21 according to the necessity of the engine 8. The purge control valve 22 is a solenoid valve that includes a casing and a valve body (both are not shown), and receives an electric signal to move the valve body. The duty of the purge control valve 22 is controlled in response to the duty signal.

A failure diagnosis device for diagnosing a failure relating to airtightness of the processing device includes a pressure sensor 41. The pressure sensor 41 is configured to be able to individually detect the tank-side internal pressure PT and the canister-side internal pressure PC with the vapor control valve 20 as a boundary. That is, the three-way switching valve 23 provided in association with the pressure sensor 41 has three ports. The three-way switching valve 23 is an electromagnetic valve that switches the communication between ports in response to supply of an electric signal. One port of the three-way switching valve 23 is a pressure sensor 41
The other two ports can communicate with the vapor line 13 on the fuel tank 1 side and the canister 14 with the vapor control valve 20 as a boundary. This three-way switching valve 2
By switching 3 as needed, the pressure sensor 41 is selectively connected to the vapor line 13 or the canister 14. Then, in response to this switching, the pressure sensor 41 selectively detects the tank-side internal pressure PT and the canister-side internal pressure PC, respectively. In addition,
In the present embodiment, the pressure sensor 41 detects the tank-side internal pressure PT.
Is set to switch so that the pressure sensor 41 communicates with the vapor line 13 when the three-way switching valve 23 is not switched by an electric signal.

Various sensors 42, 43, 44, 45, 4
6, 47 and the like detect the operating state of the engine 8 and the automobile 40. An intake air temperature sensor 42 provided in the vicinity of the air cleaner 11 detects a temperature (intake air temperature) THA of the air taken into the intake passage 10 and outputs a signal corresponding to the magnitude. An intake air amount sensor 43 provided in the vicinity of the air cleaner 11 detects an amount of air (intake amount) Q taken into the intake passage 10 and outputs a signal corresponding to the amount. The water temperature sensor 44 provided on the engine 8 is connected to the engine block 8a.
The temperature (cooling water temperature) THW of the cooling water flowing through the inside is detected, and a signal corresponding to the magnitude is output. Engine 8
A rotation speed sensor 45 provided at the sensor 8 detects a rotation speed (engine rotation speed) NE of the crankshaft 8b of the engine 8, and outputs a signal corresponding to the magnitude. An oxygen sensor 46 provided in the exhaust passage 12 detects an oxygen concentration Ox in the exhaust gas passing through the exhaust passage 12, and outputs a signal corresponding to the magnitude. A vehicle speed sensor 47 provided in the automobile 40 detects a vehicle speed SPD and outputs a signal corresponding to the magnitude. Although not shown here, various sensors and the like for detecting the operation state are provided in addition to the above.

The electronic control unit (ECU) 51 is a means for totally controlling each part of the apparatus according to this embodiment. In addition to the diagnosis means for diagnosing the presence or absence of a leak abnormality according to the present invention, a switching control means, Blockage determination means and the like are configured.

The ECU 51 is provided with various sensors 41-47.
And the like. The ECU 51
The purge control valve 22 is used to purge an amount of fuel according to the operating state of the engine 8, that is, to control the purge control valve 22 with a required duty ratio DPG.
Output the necessary duty signal. Here, the fuel purged from the canister 14 to the intake passage 10 affects the air-fuel ratio of the engine 8. Therefore, the ECU 51 determines the opening of the purge control valve 22 according to the operating state of the engine 8. Generally, when the air-fuel ratio increases, the concentration of CO contained in the exhaust gas of the engine increases. Therefore, the ECU 51 determines the purge concentration FGPG based on the value of the oxygen concentration Ox in the exhaust gas detected by the oxygen sensor 46.
Is calculated. Further, the ECU 51 determines a duty ratio DPG corresponding to the opening of the purge control valve 22 based on the calculated value, and outputs a duty signal according to the magnitude of the duty ratio DPG. That is, the ECU 51
Is different between when the engine 8 is operating and when the automobile 40 is traveling and when it is stopped, and based on the duty ratio DPG which is relatively larger when traveling than when it is stopped, the purge control valve 2
2 is duty controlled.

On the other hand, the ECU 51 is provided with the various sensors 41
The three-way switching valve 23 is switched as required based on the detected values of -47 and the like, and the value of the tank-side internal pressure PT and the value of the canister-side internal pressure PC selectively detected by the pressure sensor 41 are selectively input. The ECU 51 individually diagnoses a failure related to airtightness on the tank side and a failure related to airtightness on the canister side based on the input values of the tank-side internal pressure PT and the canister-side internal pressure PC.

In addition, the ECU 51 is connected to the various sensors 41
Diagnosis of a failure relating to the function of the purge control valve 22 and the function of the three-way switching valve 23 is performed based on the detected values such as -47. The warning lamp 24 provided in the driver's seat of the automobile 40 operates to notify the driver of the diagnosis result by the ECU 51. ECU
Reference numeral 51 turns on the warning lamp 24 when it is diagnosed that a failure has occurred in the processing apparatus and the diagnostic apparatus, and turns off the warning lamp 24 in other cases. The ECU 51 is a vehicle 40
The power supply is supplied from a battery 25 mounted on the battery and the voltage of the battery 25 is monitored.

As shown in the block diagram of FIG.
1 is a central processing unit (CPU) 52, a read-only memory (ROM) 53, a random access memory (RAM) 5
4, a backup RAM 55, a timer counter 56, and the like. The ECU 51 constitutes a logical operation circuit in which these units 52 to 56, an external input circuit 57, an external output circuit 58 and the like are connected by a bus 59. Where RO
M53 stores in advance a predetermined control program related to fuel purge, failure diagnosis, and the like. The RAM 54 temporarily stores the calculation results of the CPU 52 and the like. The backup RAM 55 stores data stored in advance. In the present embodiment, the backup RAM 55 constitutes a diagnostic data storage unit for storing a diagnostic result regarding a failure as diagnostic data. Further, the timer counter 56 can simultaneously perform a plurality of time counting operations. The external input circuit 57 includes a buffer, a waveform shaping circuit, a hard filter (a circuit including an electric resistor and a capacitor), an A / D converter, and the like. The external output circuit 58 includes a drive circuit and the like. Various sensors 41
47 and the battery 25 are connected to the external input circuit 57. Further, a purge control valve 22, a three-way switching valve 23
The warning lamp 24 is connected to an external output circuit 58.

The CPU 52 reads, as input values, the detection signals of the various sensors 41 to 47 and the like, and the voltage value VAE of the battery 24, which are input via the external input circuit 57.
The CPU 52 performs a purge control valve 22 and a three-way switching valve 2 to execute fuel purging and failure diagnosis based on the input values.
3 and the warning lamp 24 are controlled.

Next, the specific contents of the processing executed by the ECU 51 will be described. First, the operation related to the airtightness diagnosis on the fuel tank 1 side will be described focusing on the processing executed by the ECU 51. In the fuel tank 1 of the in-vehicle engine, fuel may swell inside the fuel tank 1 depending on the running state of the automobile 40 or the state of the road surface. When such a swell or the like occurs, the detected tank-side internal pressure (fuel tank internal pressure) PT also fluctuates. Particularly, when the swell occurs frequently, the pressure PT also fluctuates. Become. If the pressure PT on the tank side fluctuates frequently as described above even if the pressure fluctuates somewhat, an accurate diagnosis of the airtightness is not clear.

Therefore, in the present embodiment, the following various processes are executed through the ECU 51. First, when diagnosing the airtightness of the fuel tank 1 side, the diagnosis is basically performed in the present embodiment based on the method illustrated in FIG. The outline is described below.

The tank side internal pressure (fuel tank internal pressure) P
When the engine 8 is started at a low temperature, as shown by a solid line in FIG. 3, T is temporarily reduced due to a decrease in the liquid level (fuel consumption) after the start, and becomes a negative pressure. Normally, the pressure becomes the lowest in about 5 minutes after starting. Then, as the fuel temperature rises due to the recirculation of surplus fuel, the pressure P
T gradually increases. Normally, the pressure rises to near the set value of the vapor control valve (internal pressure control valve) 20 about 20 minutes after the start.

On the other hand, when the engine 8 is started at a high temperature, such as when it is restarted in a short time after the engine 8 is stopped, as shown by a broken line in FIG. After the engine is started, the temperature rises to a value close to the set value of the vapor control valve 20 in a relatively short time after the start.

However, the fuel tank 1 and the vapor line 1
If a leak occurs due to a hole or a crack in 3, the pressure PT is communicated to the atmosphere through the leaked portion. Therefore, in this case, the pressure PT is maintained near the atmospheric pressure regardless of the fuel temperature, as shown by the dashed line in FIG.

In view of these characteristics of the tank-side internal pressure PT, the pressure PT is set within a predetermined time (for example, within about 20 minutes after the start) after the start of the engine 8 in FIG. Is diagnosed as "normal" when the pressure becomes equal to or less than the negative pressure PT2 or equal to or more than the predetermined positive pressure PT1, and as "abnormal" otherwise. Here, these determination values P
T1 and PT2 are set according to the size of the leak to be detected. Incidentally, when a hole having a diameter of about 1 mm is to be detected, the determination value PT1 is “atmospheric pressure + 0.3 KPa (30
mmAq) ", and the determination value PT2 is set to a negative pressure of" atmospheric pressure-0.3 KPa (30 mmAq) ".

In addition, the number of occurrences of the swell (the swell counter I, which is managed through a swell determination routine to be described later).
NTP count value), and when this number is equal to or greater than the predetermined determination value α, it is determined that frequent pressure fluctuations occur in the fuel tank 1 that hinder the accurate airtightness diagnosis described above. The diagnosis is interrupted.

FIG. 4 shows an example of a diagnosis routine for diagnosing the airtightness of the fuel tank 1 based on such an algorithm. This diagnostic routine is executed through the ECU 51 as a time interruption routine at regular intervals. In addition, this routine is a prerequisite for this. ・ No abnormality of the diagnostic system including the pressure sensor 41 has been detected. -The voltage of the battery 25 is within a normal value range. The intake air temperature THA and the cooling water temperature THW are within a predetermined temperature range. These conditions are confirmed in advance through the ECU 51, and are executed on condition that all of the preconditions are satisfied.

Now, in this diagnosis routine, the ECU
First, at step 100, it is determined whether or not the start of the engine 8 has been completed. The ECU 51 determines that the start of the engine 8 has been completed when the engine speed NE becomes equal to or higher than a predetermined value (for example, 400 rpm). If the start of the engine 8 has not been completed, the ECU 51
At step 101, the timer value T of the timer for measuring the time after the engine is started is reset (T ← 0), and at step 102, a flag K indicating whether or not the diagnosis has been completed.
D is set to “0” indicating that diagnosis has not been completed (KD ←
0), once exit this routine.

On the other hand, if the start of the engine 8 has been completed, the ECU 51 checks the state of the flag KD in step 110, and on condition that "1" indicating the end of the diagnosis is not set in this flag KD. That is, on condition that "KDＫ1", the timer value T is incremented (T ← T + 1) in step 111.

Next, the ECU 51 that has incremented the timer value T determines in step 112 whether the timer value T has reached a predetermined value T0 (for example, a value corresponding to 20 minutes after starting). If the timer value T has not reached the predetermined value T0, the value of the tank-side internal pressure (fuel tank internal pressure) PT is read in step 113.

When the pressure value PT is read, the ECU 51
In order to execute the airtightness diagnosis on the side of the fuel tank 1 in the mode illustrated in FIG. 3, in steps 114 and 115, it is determined whether or not the pressure value PT is equal to or less than the determination value PT2, and It is determined whether or not it is above.

Then, as a result, if it is confirmed that the pressure value PT is equal to or less than the determination value PT2, or that the pressure value PT is equal to or greater than the determination value PT1, the ECU 51 On the condition that it is determined in step 118 that the count value of the swell counter INTP, which is incremented through the swell determination routine (FIG. 5) described later, is smaller than the determination value α, the diagnosis flag is determined in step 119. FX is set to “0” indicating normal (FX
← 0). Then, in this case, after the flag KD is set to "1" indicating the end of the diagnosis in the next step 120 (KD ← 1), the routine once exits.

If it is determined in step 118 that the count value of the swell counter INTP is equal to or greater than the determination value α, the normality is not diagnosed, and the process proceeds to step 102. After the flag KD is set to “0” indicating that diagnosis has not been completed, (KD ←
0), once exit this routine.

This is a consideration for the concern that "when the swell or the like frequently occurs in the fuel tank 1, the tank-side internal pressure PT also fluctuates frequently, so that an accurate diagnosis of the airtightness cannot be obscure." As described above.

On the other hand, as a result of the diagnosis for the pressure value PT, the following are obtained: the pressure value PT is higher than the judgment value PT2; and the pressure value PT is lower than the judgment value PT1. If it is determined in step 117 that the diagnosis flag FX is abnormal, the ECU 51 determines in step 117 that the count value of the swell counter INTP is less than the determination value α. Is set (FX ← 1) to indicate that
Exit from the routine once. In this case as well, if it is determined in step 116 that the count value of the swell counter INTP is equal to or greater than the determination value α, the diagnosis in step 1 is performed without performing the abnormality diagnosis.
After setting the flag KD to "0" indicating that diagnosis has not been completed through 02 (KD ← 0), the routine once exits.

Similarly, this is a consideration for a concern such as "when swell occurs frequently in the fuel tank 1, the tank-side internal pressure PT also fluctuates frequently, so that accurate diagnosis of the airtightness is not obvious." .

Thereafter, if it is determined in step 112 that the timer value T has reached the predetermined value T0 by repeatedly executing the diagnostic routine, step 120 is executed.
The flag KD is set to "1" indicating the end of the diagnosis (KD ← 1), and the routine exits.

In step 110, "KD
If it is determined that “= 1”, the routine exits the routine. It should be noted that in the failure diagnosis device, the normal (FX = 0) or abnormal (FX =
The diagnosis result to the effect of 1) is stored in the backup RAM 5
5 is registered. If the registered diagnosis result indicates an abnormality (FX = 1), the EC
U51 controls the lighting of the warning lamp 24 to notify the driver of this.

As described above, in this diagnostic routine, FIG.
In the diagnosis of the airtightness of the fuel tank 1 illustrated in FIG. 1, the undulation of the fuel is determined in the above-described manner, and the diagnosis operation is interrupted.

Further, in the present embodiment, in parallel with the above-described airtightness diagnosis processing, the tank internal pressure extraction routine and the swell determination routine exemplified in FIGS. I have to.

The details of the tank internal pressure extraction routine and the swell determination routine will be described below with reference to FIGS. 5 and 6. The ECU 51 monitors the tank side internal pressure (fuel tank internal pressure) PT through a tank internal pressure extraction routine shown in FIG. This tank pressure extraction routine
For example, it is executed as a time interruption routine every 64 msec.

In this tank internal pressure extraction routine, E
The CU 51 first determines in step 200 whether or not the engine 8 has been started.
A / D for tank-side internal pressure PT detected above
The conversion value PTAD is registered in a predetermined area in the RAM 54 as a smoothed value (gradual change value) PTSMi for the same pressure PT.

On the other hand, if it is determined in step 200 that it is not at the time of starting, the ECU 51 determines in step 202 that A / A of the detected tank-side internal pressure PT.
Based on the D-converted value PTAD and the previous smoothed value (the value registered in the RAM 54) PTSMi-1 for the same pressure PT, the smoothed operation PTSMi = PTSMi-1 + (PTAD-PTSMi-1) / 4 (4) 1) is executed to obtain a new averaging value PTSMi, and the averaging value PTSMi-1 in the RAM 54 is updated with the obtained averaging value PTSMi.

In the tank internal pressure extraction routine, such processing is repeatedly executed, for example, every 64 msec.
The ECU 51 also manages the presence / absence of the above-mentioned undulation and the number of occurrences of the undulation through the undulation determination routine shown in FIG. This undulation determination routine is performed, for example, for 1 second.
It is executed as an interrupt routine every time.

In this undulation determination routine, the ECU
First, at step 300, it is determined whether or not the engine 8 has been started. If it is time to start the engine, in step 301, the ECU 51 calculates the smoothing value PTSM for the tank-side internal pressure PT registered in the RAM 54 to the same pressure P in order to start the swell determination.
The average value PTW for swell determination of T and the pressure reference value PTO for each determination are registered in other areas in the RAM 54. Then, the subsequent processing ends once.

On the other hand, if it is determined in step 300 that it is not at the time of starting, in step 302, the ECU 51 determines whether or not the tank side internal pressure PT registered in the RAM 54 at that time is 64 bytes.
An average value PTSM every msec and an average value every 1 sec for the same pressure PT (an average value for undulation determination) PTW
Based on i-1, the smoothing operation PTWi = PTWi-1 + (PTSM-PTWi-1) / 8 (2) is executed to newly obtain the swell judgment smoothing value PTWi.

The ECU 51 further proceeds to step 30
In 3, the swell determination smoothing value PTW obtained above is obtained.
And whether or not the absolute value of the difference between the pressure reference value PTO registered in the RAM 54 at that time is equal to or more than “0.275 mmHg”, that is, | PTW−PTO | ≧ 0.275 mmHg (3) Is determined. As a result, if the relationship of the equation (3) is satisfied, it is determined that swell has occurred, and in step 304, the swell counter INTP is incremented, and the obtained swell determination smoothing value is obtained. PTW to new pressure reference value PTO
Is updated and registered in a corresponding area in the RAM 54.

If the relationship of the above equation (3) is not satisfied, it is determined that no swell has occurred, and the swell counter INTP is not incremented and the pressure reference value PTO is not updated. Exit from the routine once.

In the waviness determination routine illustrated in FIG. 6, the predetermined pressure (in the above example, “0.275 mmH”) of the tank-side internal pressure (more precisely, the smoothed value PTW) is thus obtained.
g ", see equation (3)).
It is determined that swell has occurred, and the swell counter IN
Increment TP. Is 1s for example
This is repeatedly executed for each ec. For this reason, according to the failure diagnostic apparatus of the embodiment for performing the airtightness diagnosis on the fuel tank 1 side based on the above-described diagnosis routine (FIG. 4), the swelling frequently occurs, and If the airtight diagnosis is not performed, the diagnosis operation is prohibited. For this reason, erroneous diagnosis in the same situation is suitably suppressed.

When the vapor line 13 extending from the fuel tank 1 to the vapor control valve 20 or the communication passage connecting the vapor line 13 and the three-way switching valve 23 is closed for some reason, the above-mentioned condition is obtained. Such a blockage cannot be detected only by the diagnosis routine (FIG. 4). In addition, if an obstruction occurs,
The tank side internal pressure PT is also not accurate. As a result, despite the presence of holes or the like in the fuel tank 1, the vapor line 13, or the like, there is a possibility that the abnormality cannot be diagnosed and that the diagnosis is normal (erroneous diagnosis). is there.

On the other hand, in the present embodiment, it is determined whether or not the vapor line 13 or the communication passage has been closed. 7 to 9 show an example of the processing. That is, FIGS. 7 and 8 show a routine for determining whether or not there is a blockage, and FIG.
Example of behavior of tank side internal pressure PT (timing chart)
Is shown.

First, the blockage determination routine shown in FIGS. This blockage determination routine is executed as an interrupt routine at predetermined time intervals. In this blockage determination routine, the ECU 51 first determines in step 401 whether the tank-side internal pressure measurement flag XTPC is “1”. Here, the tank-side internal pressure measurement flag XT
PC is a flag indicating whether to measure the tank-side internal pressure PT or the canister-side internal pressure PC, and the ECU 51 controls the three-way switching valve 23 based on the flag. That is, the tank-side internal pressure measurement flag XTPC
Is "1", the pressure sensor 41 and the vapor line 1
Thus, the three-way switching valve 23 is controlled so that the tank 3 communicates with the tank 3, and the tank-side internal pressure PT can be measured. On the other hand, when the tank-side internal pressure measurement flag XTPC is “0”, the pressure sensor 41
The three-way switching valve 23 is controlled so that the canister 14 and the canister 14 communicate with each other, and the canister-side internal pressure PC can be measured.

Then, the tank side internal pressure measurement flag XTPC
Is “1”, that is, when the tank-side internal pressure PT can be measured, the process proceeds to step 402. In step 402, the ECU 51 determines whether or not the blockage determination has already been completed. Then, if the blockage determination has already been completed, the subsequent processing is temporarily terminated without performing any processing. On the other hand, if the occlusion determination has not been completed, it is determined in step 403 whether the second count value CXTPC2 of the determination time counter (which will be described later) is “0”. . Then, the second count value CXTPC2 is “0”.
In the case of, the process proceeds to step 404.

In step 404, an average value PTS of the current tank-side internal pressure PT every 64 msec.
It is determined whether M (see the above routine) is greater than a predetermined positive pressure PT1. If the smoothed value PTSM of the tank-side internal pressure PT is not larger than the positive pressure PT1, it is determined that it is not always appropriate to perform the determination, and the subsequent processing is temporarily terminated. If the smoothed value PTSM for the tank-side internal pressure PT is larger than the positive pressure PT1, the process proceeds to step 405.

In step 405, it is determined whether the current duty ratio DPG of the purge control valve 22 is equal to or greater than a predetermined value (for example, "20%"). Then, even when the duty ratio DPG is less than the predetermined value,
It is determined that it is not always appropriate to perform the determination, and the subsequent processing is temporarily terminated. If the duty ratio DPG is equal to or larger than the predetermined value, the process proceeds to step 406.

At step 406, the ECU 51
The smoothed value PTSM of the tank-side internal pressure PT at that time every 64 msec is changed to a reference value PTBS of the tank-side internal pressure.
Set as E. At the same time, the first count value CXTPC1 of the determination time counter is incremented. Further, thereafter, the tank-side internal pressure measurement flag XTPC is set to “0” in order to switch and control the three-way switching valve 23 so that the pressure sensor 41 and the canister 14 communicate with each other. This enables the canister-side internal pressure PC to be measured at the next transition to the present routine. Then, the subsequent processing ends once.

By setting the tank-side internal pressure measurement flag XTPC to "0", a negative determination is made in step 401 at the next shift to the present routine. In such a case, the process proceeds to step 407. In step 407, it is determined whether the first count value CXTPC1 of the determination time counter is "0". When the first count value CXTPC1 is “0”, the subsequent processing is temporarily terminated. On the other hand, if the first count value CXTPC1 has been incremented through the above step 406, the first count value CXTPC1 has not become “0”.
Move to 8.

In step 408, it is determined again whether the current duty ratio DPG of the purge control valve 22 is equal to or greater than a predetermined value (for example, "20%").
When the duty ratio DPG is less than the predetermined value, it is determined that it is not always appropriate to perform the determination.
Move to step 409.

In step 409, the ECU 51
The canister side pressure PC is not so negative,
Thereafter, the tank-side internal pressure measurement flag XTPC is forcibly set to "1" on the assumption that the tank-side internal pressure PT should be detected. At the same time, the first count value CXT
PC1 is cleared to "0". Then, the subsequent processing ends once.

On the other hand, if the duty ratio DPG is equal to or greater than the predetermined value, in step 410, the first count value CXTPC1 is further incremented. Also,
In the following step 411, the first count value CXT
It is determined whether or not PC1 has exceeded a predetermined time (for example, “3 seconds”). If the first count value CXTPC1 does not exceed the predetermined time, the canister-side internal pressure PC is determined not to be a calm value and the subsequent processing is temporarily terminated. On the other hand, if the first count value CXTPC1 exceeds the predetermined time, it is determined that the canister-side internal pressure PC has reached a calm value, and the routine proceeds to step 412.

In step 412, the tank-side internal pressure measurement flag XTPC is forcibly set to "1" in order to detect the tank-side internal pressure PT again. This allows
The pressure sensor 41 and the vapor passage 13 are communicated with each other, and the canister-side internal pressure PC can be measured at the next transition to this routine. At the same time, the second count value CXTPC2 of the determination time counter is incremented. Then, the subsequent processing ends once.

As described above, when the tank side internal pressure measurement flag XTPC is set to “1” again and the second count value CXTPC2 is incremented, at the next transition to the present routine, In step 401, an affirmative determination is made, a negative determination is made in step 402, and a negative determination is made in step 403. In such a case, the process proceeds to step 413 (FIG. 8). In step 413, the second count value CXTPC2 is further incremented, and in the next step 414, the second count value CXTPC1 is increased by a predetermined time (for example, “3”).
Seconds "). If the second count value CXTPC2 does not exceed the predetermined time, it is determined that the tank-side internal pressure PT has not become a calm value, and the subsequent processing is temporarily terminated. On the other hand, if the second count value CXTPC2 has exceeded the predetermined time, it is determined that the tank side internal pressure PT has become a calm value, and the routine proceeds to step 415.

In step 415, the reference value PTBSE of the tank-side internal pressure set in step 406 is used to calculate 64 msec for the tank-side internal pressure PT at that time.
The average value PTSM for each c is subtracted, and it is determined whether or not the value is greater than a predetermined determination value ε. And
If the subtraction value is not larger than the determination value ε, the process proceeds to step 416.

At step 416, it is determined that no blockage has occurred, and the blockage determination flag XD is set to "0". At the same time, the first and second count values CXTPC1 and CXTPC2 are both cleared to "0". After setting the end of the blockage determination, the subsequent processing is temporarily terminated.

On the other hand, when the subtraction value is larger than the judgment value ε, in step 417, the vapor line 1 from the fuel tank 1 to the vapor control valve 20 is
3, or it is determined that the communication path connecting the vapor line 13 and the three-way switching valve 23 has been closed for some reason, and the closing determination flag XD is set to “1”. At the same time, the first and second count values CX
Clear both TPC1 and CXTPC2 to “0”. After setting the end of the blockage determination, the subsequent processing is temporarily terminated. Even when the blockage determination flag XD is set to "1", the ECU 51 turns on the warning lamp 24 provided in the driver's seat of the automobile 40 to notify the driver of the blockage.

Next, the operation and effect of this embodiment will be described. (A) In the present embodiment, as shown in FIG.
1 controls the switching of the three-way switching valve 23, whereby the pressure detected by the pressure sensor 41 changes from (i) tank-side internal pressure PT to (ii) canister-side internal pressure PC to (iii).
The order is the tank side internal pressure PT. Then, (ii) the reference value PTBSE, which is the smoothing value PTSM based on the tank-side internal pressure PT detected by the pressure sensor 41 before the canister-side internal pressure PC is detected, and (ii) the canister-side internal pressure PC (Iii) smoothed value PTS of tank-side internal pressure PT detected by pressure sensor 41 after
Based on the difference from M (pressure difference ΔP), the presence or absence of blockage is determined. Specifically, when the pressure difference ΔP is larger than the determination value ε, the vapor line 13 extending from the fuel tank 1 to the vapor control valve 20 or the communication path communicating the vapor line 13 with the three-way switching valve 23 is It is determined that it has been blocked due to the cause.

Here, as shown by the solid line in the figure, the vapor line 13 or the vapor line 13 and the three-way switching valve 23
If the communication path that communicates with the valve has been closed for some reason, the three-way switching valve 23 is switched after the switching.
(iii) Since the tank-side internal pressure PT has a small internal volume, the tank-side internal pressure PT is susceptible to (ii) the canister-side internal pressure PC. May cause a relatively large pressure difference ΔP.
Therefore, according to the present embodiment, the pressure difference ΔP (PT
Based on the BSE-PTSM), it is possible to reliably determine the presence or absence of the blockage. As a result, if the vapor line 13 or the like is closed for some reason, it can be reliably determined, and at the time of abnormality diagnosis (FIG. 4), a hole or the like exists in the fuel tank 81 or the like. In spite of this, it is possible to avoid a situation in which the abnormality cannot be diagnosed and a normal diagnosis (erroneous diagnosis) is made. As a result, the failure diagnosis can be further optimized.

(B) In the present embodiment, (i) the smoothing value PT based on the tank-side internal pressure PT before switching is performed.
The above determination is made only when SM exceeds a predetermined pressure (positive pressure PT1) greater than the atmospheric pressure. For this reason,
If the vapor line 13 or the like is closed, the pressure difference ΔP of the tank-side internal pressure PT before and after the switching becomes large. Therefore, in this case, the detection of the blockage can be performed more easily, and for example, the determination value ε can be set relatively large, and the determination of the blockage can be made more reliable.

(C) Further, in the present embodiment, the duty ratio DPG of the purge control valve 22 during the period when (ii) the canister-side internal pressure PC is detected by the pressure sensor 41.
Is determined only when it is equal to or more than a predetermined value (for example, “20%”). As described above, the fact that the duty ratio DPG is equal to or greater than the predetermined value indicates that (ii) the canister-side internal pressure PC has a relatively small value (a large value on the negative pressure side) as shown in FIG. Accordingly, also in this case, if the vapor line 13 or the like is closed, the pressure difference ΔP of the tank-side internal pressure PT before and after the switching becomes large. Therefore, the detection of the blockage can be performed more easily, and the determination of the blockage can be made more reliable by setting the determination value ε relatively large.

The present invention is not limited to the above-described embodiments, but may be implemented as follows by appropriately changing a part of the configuration without departing from the spirit of the invention. (1) In the above embodiment, “(i)
The above determination is made only when the smoothing value PTSM based on the "tank-side internal pressure PT" exceeds a predetermined pressure (positive pressure PT1) larger than the atmospheric pressure. In contrast,
The above determination may be made even when “(i) tank-side internal pressure PT” or the smoothed value PTSM is not greater than the atmospheric pressure. Further, a value different from the positive pressure in FIG. 4 may be used as the positive pressure PT1.

Further, in this case, a blockage determination as described below may be performed. That is, as shown in FIG. 10, first, “(i) tank-side internal pressure PT”,
Even if the smoothed value PTSM does not exceed the atmospheric pressure, if the pressure difference ΔP of the tank-side internal pressure PT before and after the switching is larger than a predetermined determination value, a temporary blockage determination is performed, and the three-way switching valve is switched again. Switching control is performed in the same manner as described above. At this time, the duty ratio DPG of the purge control valve 22 is forcibly set to a large value while “(ii) canister side internal pressure PC” is detected by the pressure sensor 41. By such control, “(ii) canister-side internal pressure PC” becomes a relatively small value (a large value on the negative pressure side). Therefore, also in this case, if the vapor line 13 or the like is closed, the pressure difference ΔP of the tank side internal pressure PT before and after the switching becomes large, and the detection of the blockage can be reliably performed.

(2) In the above embodiment, the duty ratio DP of the purge control valve 22 during the period in which “(ii) canister side internal pressure PC” is detected by the pressure sensor 41.
The determination is made only when G is equal to or greater than a predetermined value (for example, “20%”). However, for the same purpose as in (1) above, the duty ratio DPG does not exceed the predetermined value. In such a case, the determination may be made.
This is particularly true when the smoothing value PTSM based on “(i) tank side internal pressure PT” before switching is large.

(3) In the above embodiment, the smoothed value PTSM of the tank-side internal pressure PT is used for the determination of the blockage or the like, but the tank-side internal pressure PT may be used as it is.

(4) In the above embodiment,
Although the airtightness of the fuel tank 1 is diagnosed in the mode illustrated in FIG. 4, another diagnostic method may be employed for the airtightness of the fuel tank 1.

For example, in the diagnostic method illustrated in FIG. 4, the presence or absence of the airtightness abnormality is diagnosed based on the absolute value of the tank side internal pressure (fuel tank internal pressure) PT. On the other hand, for example, the difference ΔPT between the lowest pressure PTmin reached by the tank-side internal pressure PT and the highest pressure PTmax within a predetermined time after starting the engine is determined by the determination value ΔPTO.
(For example, about 0.6 KPa) or more may be diagnosed as normal, and if less than the same determination value ΔPTO, it may be diagnosed as abnormal.

Further, for example, a method of diagnosing the airtightness of the fuel tank 1 based on the time integral value of the tank internal pressure (fuel tank internal pressure) PT can be appropriately adopted.

[0092]

As described above, according to the present invention,
In a failure diagnosis device of a fuel vapor processing device for diagnosing airtightness on a fuel tank side, a vapor passage from a fuel tank to an internal pressure control valve, or a communication passage connecting a vapor passage and a three-way switching valve is closed. In this case, it is possible to make a reliable determination, and furthermore, it is possible to achieve an excellent effect that the failure diagnosis can be further optimized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a failure diagnosis device according to the present invention.

FIG. 2 is an exemplary block diagram showing electrical connection centering on the ECU of the embodiment;

FIG. 3 is a graph showing an example of an airtightness diagnosis method on the tank side.

FIG. 4 is a flowchart showing a diagnostic routine executed by the ECU.

FIG. 5 is a flowchart showing a tank internal pressure extraction routine executed by the ECU.

FIG. 6 is a flowchart showing a swell determination routine executed by the ECU.

FIG. 7 is a flowchart showing a blockage determination routine executed by the ECU.

FIG. 8 is a flowchart showing a blockage determination routine continued from FIG. 7;

FIG. 9 is a timing chart showing an example of a pressure behavior when a vapor passage or the like is closed.

FIG. 10 is a timing chart showing an example of a pressure behavior in another embodiment.

FIG. 11 is a schematic configuration diagram showing a conventional fuel vapor processing device.

FIG. 12 is a schematic configuration diagram showing a failure diagnosis device of a conventional fuel vapor processing device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel tank, 8 ... Engine, 10 ... Intake passage, 13
... Vapor line, 14 ... Canister, 20 ... Vapor control valve (internal pressure control valve), 21 ... Purge line, 22 ... Purge control valve, 23 ... Three-way switching valve, 24 ... Warning lamp, 40 ...
An automobile as a vehicle, 41 a pressure sensor, 51 an electronic control unit (ECU).

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI G01M 15/00 G01M 15/00 Z (56) References JP-A-6-108930 (JP, A) JP-A 7-12014 (JP, A) JP-A-6-129244 (JP, A) JP-A-8-270480 (JP, A) JP-A-9-42076 (JP, A) JP-A-6-108932 (JP, A) 256214 (JP, A) JP-A-9-42074 (JP, A) JP-A-9-14059 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 25/08 301 F02M 25/08 F02B 77/08 G01M 15/00

Claims (4)

(57) [Claims] A purge device for purging fuel vapor from a fuel tank to an engine intake passage through a vapor passage, a canister, and a purge passage; and a purge device provided between the vapor passage and the canister; When the pressure becomes equal to or higher than a predetermined pressure higher than the atmospheric pressure, an internal pressure control valve that opens to maintain the internal pressure of the fuel tank at a predetermined pressure or less; A pressure sensor for detecting an internal pressure, and a pressure detected by the pressure sensor, for switching between the fuel tank internal pressure and the purge passage side internal pressure, between the fuel tank and the pressure sensor and the pressure sensor. A fuel tank having a three-way switching valve for switching a communication state between a purge passage and a pressure sensor, the fuel tank being detected by the pressure sensor after engine startup In the failure diagnosis device for a fuel vapor processing device, which monitors the internal pressure to determine whether or not there is a leakage abnormality on the fuel tank side, the pressure detected by the pressure sensor includes a fuel tank internal pressure, a purge passage side internal pressure, and a fuel tank. Switching control means for switching the three-way switching valve so as to be in the order of the internal pressure, and a fuel tank internal pressure detected by the pressure sensor before the purge passage side internal pressure is detected by the pressure sensor; Based on the pressure difference between the pressure in the fuel tank and the pressure in the fuel tank detected by the pressure sensor after the pressure in the purge passage is detected by the pressure sensor, the vapor passage, or between the internal pressure control valve and the three-way switching valve, A failure diagnosis device for a fuel vapor processing device, comprising: a blockage determination unit configured to determine whether a communicating communication path is blocked. 2. The fuel vapor processing apparatus according to claim 1, wherein the blockage determination unit determines that the blockage is made when the pressure difference is larger than a predetermined determination value. Fault diagnosis device. 3. The fuel cell system according to claim 1, wherein the pressure sensor detects the pressure in the fuel tank before the pressure sensor detects the pressure in the purge passage.
3. The failure diagnosis device for a fuel vapor processing device according to claim 1, wherein the failure diagnosis is performed when a predetermined pressure greater than the atmospheric pressure is exceeded. 4. The determination by the blockage determining means is performed when the purge control of the fuel vapor is executed during a period in which the pressure sensor detects the pressure in the purge passage. The failure diagnosis device for a fuel vapor processing device according to any one of claims 1 to 3, wherein: