JPH1026055A - Trouble diagnosing device for fuel steam treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of erroneous diagnosis stating that a fuel tank is normal before it is decided that the tank is full of fuel, in a trouble diagnosing device for a fuel steam treating device to decide it based on the number of slosh occurring times that a tank is full of fuel and suspend diagnosis thereof. SOLUTION: An electronic control device (ECU) 51 monitors a pressure in a fuel tank 1 through a pressure sensor 41 and diagnoses it based on whether a pressure indicates given behavior whether airtightness on the fuel tank 1 side is normal or abnormal. Further, the ECU 51 detects the occurrence of slosh, being leap of fuel in the fuel tank 1, based on a fact that a pressure to be monitored is changed by a given value or more, and counts the number of occurring times. When a count value attains a given value, it is decided that the tank is full of fuel and diagnosis is suspended. In this case, by lowering a threshold to a count value to allow diagnosis stating that the tank is normal, diagnosis stating that it is normal is hardly effected.

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 to 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 apparatus uses a fuel vapor generated in a fuel tank 71 for vapor line 72.
Has a canister 73 that collects through the canister. The canister 73 incorporates an adsorbent 74 made of activated carbon or the like. A purge line 75 extending from the canister 73 communicates with an intake passage 77 of the engine 76. The canister 73 causes the adsorbent 74 to once adsorb the fuel vapor introduced from the vapor line 72. The canister 73 collects only the fuel and discharges only the gas containing no fuel component, particularly, hydrocarbon (HC) from the communication hole 78 to the outside. Further, when the engine 76 is operating, the canister 73 purges the once collected fuel to the intake passage 77 through the purge line 75. 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 processed as intended.

Japanese Patent Laid-Open Publication No. Hei 6-108930 discloses an apparatus for diagnosing the above-described failure. As shown in FIG. 12, the fuel vapor processing apparatus targeted by the failure diagnosis apparatus has 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 to the intake passage 80. Purge VSV provided in the middle of purge line 84
(Purge control valve) 85 is controlled and opened by an electronic control unit (ECU) 86 during operation of the engine. 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. The control valve 87 is a check valve including a check ball, and 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 flow of fuel vapor from the fuel tank 81 to the canister 82 is permitted. Another control valve 90 provided in a passage bypassing the vapor control valve 87 with respect to the vapor line 83 is controlled by the ECU 86. When the control valve 90 is opened when the vapor control valve 87 is closed, fuel vapor generated in the fuel tank 81 flows to the canister 82. The diagnostic device has a pressure sensor 88 which 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 other two ports of the three-way switching valve 89 connected to the pressure sensor 88 are connected to the vapor line 83 on the fuel tank 81 side and the vapor line 83 on the canister 82 with the vapor control valve 87 as a boundary. The ECU 86 controls the three-way switching valve 89
Is switched as needed, so that the pressure sensor 88
Detects the tank-side internal pressure and the canister-side internal pressure, respectively. The ECU 86 individually diagnoses the airtightness on the tank side and the airtightness on the canister side based on the detected internal pressure value on the tank side and the detected internal pressure value on the canister side.

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, and will 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.

[0006]

As described above, on the fuel tank side, basically, it is determined whether the pressure in the fuel tank detected by the pressure sensor is higher than a predetermined reference value or not. Diagnosis of the airtightness can be performed based on whether or not the internal pressure changes more than a predetermined value.

By the way, in such a fuel tank of an on-vehicle engine, fuel splashing called slosh may occur inside the fuel tank depending on the running condition of the vehicle. When such a slosh occurs, the detected pressure in the fuel tank also fluctuates. In particular, when such a slosh occurs frequently when the fuel is full, the blockage / release of the vapor line is repeated due to the rough surface of the liquid. As a result, for example, a disturbance as shown in FIG. 13A is superimposed on the detected fuel tank pressure. And, of course, when such a disturbance is superimposed on the detected fuel tank pressure, the accurate diagnosis of the airtightness will not be obvious.

[0008] Conventionally, there has been proposed a failure diagnosis device or the like in which when such a slosh is detected based on a predetermined change in the detected fuel tank pressure, the same airtightness diagnosis is stopped. (See, for example, JP-A-6-159157).

However, in such a failure diagnosis device, it is originally desirable that the diagnosis state be maintained as long as possible unless an erroneous diagnosis is performed, and the diagnosis operation is stopped only when the occurrence of slosh is detected. The diagnostic structure of the device remains questionable.

On the other hand, in order to positively maintain the diagnostic operation even in the situation where the slosh is generated, for example, FIG.
In the mode shown in (b), the number of slosh occurrences after the engine is started is counted by a counter, and it is determined that the fuel is full only when the count value is equal to or more than a predetermined value (for example, “30”). A diagnostic structure in which the diagnostic operation is stopped and the diagnostic operation is stopped is also conceivable.

When a disturbance as shown in FIG. 13A is superimposed on the detected fuel tank pressure due to the full fuel, accurate diagnosis itself is difficult in the first place. It can be said that the diagnostic structure in which the diagnostic operation is stopped under such conditions is more preferable than the diagnostic structure of the above-described device in which the occurrence of the slosh is simply detected and the diagnostic operation is stopped.

However, when the fuel is full, even if there is an abnormality such as a hole in the fuel tank or the vapor line, a negative pressure is generated in the tank due to fuel consumption because the vapor volume in the tank is small in the first place. I do. For this reason, even though there is an abnormality such as the hole or the like, the count value is erroneously determined to be “normal” before the count value reaches a predetermined value (in this case, “30”), for example, in the mode shown in FIG. There is a concern that the diagnosis will be made.

The present invention has been made in view of such circumstances, and while employing a diagnostic structure for judging that the fuel is full based on the number of slosh occurrences and interrupting the diagnosis, the above-described unintended erroneous It is an object of the present invention to provide a failure diagnosis device for a fuel vapor treatment device that can suitably prevent the execution of a diagnosis.

[0014]

In order to achieve the above object, according to the first aspect of the present invention, a fuel tank is provided between a purge device for purging fuel vapor into an engine intake passage and a fuel tank. It has an internal pressure control valve that opens when the pressure becomes equal to or higher than a predetermined pressure higher than the atmospheric pressure and maintains the internal pressure of the fuel tank at a predetermined pressure or lower, and a pressure sensor that detects the internal pressure of the fuel tank. As a failure diagnosis device for a fuel vapor processing device that monitors the pressure in the fuel tank after starting the engine and diagnoses the airtightness of the fuel tank side, (a) detecting the occurrence of slosh, which is a jump of fuel in the fuel tank Slosh detection means. (B) A counter for counting the number of occurrences of the detected slosh. (C) first diagnostic means for diagnosing whether or not the airtightness on the fuel tank side is normal on condition that the count value of the counter is less than a first predetermined value. (D) a second diagnosis for diagnosing whether or not the airtightness on the fuel tank side is abnormal on condition that the count value of the counter is smaller than a second predetermined value larger than the first predetermined value. means. Respectively.

According to this configuration of the failure diagnosis device, the allowable value for the count value of the counter, which can diagnose that the airtightness on the fuel tank side is normal, that is, the first predetermined value and The allowable value for the count value of the counter capable of diagnosing that the airtightness on the fuel tank side is abnormal, that is, the second predetermined value, the first predetermined value <the second predetermined value. When the number of occurrences of the slosh becomes equal to or more than the first predetermined value, the diagnosis of at least “normal” is prohibited, and thereafter, the number of occurrences of the slosh becomes equal to or more than the second predetermined value. At that point, the diagnosis of “abnormal” is also prohibited.

For this reason, even if the diagnosis is interrupted when it is determined that the fuel is full based on the number of times of slosh occurrence, it is difficult to make at least a "normal" diagnosis, and, consequently, the "normal" state. It is also difficult to make an erroneous diagnosis of the fact.

In the same construction as the failure diagnosis device, the second predetermined value may be a value for determining that the fuel in the fuel tank is full. Set to a value corresponding to the number of slosh occurrences. According to such a configuration, the suppression effect on the above-described “normal” diagnosis is more remarkable, and the erroneous diagnosis is more reliably suppressed.

On the other hand, according to the third aspect of the present invention, the fuel tank is provided between the purge device for purging fuel vapor into the engine intake passage and the fuel tank, and is opened when the pressure in the fuel tank exceeds a predetermined pressure higher than the atmospheric pressure. An internal pressure control valve for maintaining the internal pressure of the fuel tank at a predetermined pressure or lower, and a pressure sensor for detecting the internal pressure of the fuel tank, and monitoring the detected internal pressure of the fuel tank after engine start. (A) slosh detecting means for detecting the occurrence of slosh, which is a jump of fuel in the fuel tank. (B) A counter for counting the number of occurrences of the detected slosh. (E) threshold value setting means for variably setting a threshold value for the count value of this counter according to the elapsed time after the engine is started. (F) Diagnosis prohibiting means for prohibiting diagnosis of whether the airtightness on the fuel tank side is normal or abnormal on condition that the count value of the counter is equal to or more than the variably set threshold value. Respectively.

Generally, the frequency of occurrence of the slosh changes according to the degree of fullness of the fuel in the fuel tank. The degree of fullness of the fuel also changes according to the elapsed time after starting the engine due to the consumption of the fuel.

Therefore, according to such a configuration as the failure diagnosis apparatus, it is possible to determine with a higher accuracy whether or not the fuel is full based on the above count value. Such misdiagnosis becomes difficult.

Further, according to the invention of claim 4,
(E1) a first threshold value that is referred to when diagnosing whether or not the airtightness of the fuel tank is normal; and a first threshold value that is larger than the first threshold value and that is larger than the first threshold value. The second threshold value, which is referred to when diagnosing whether the airtightness is abnormal or not, is variably set. With this configuration, it is difficult to diagnose at least "normal" as in the first or second aspect of the present invention, and it is also difficult to mistakenly diagnose "normal".

On the other hand, according to the present invention, the fuel tank is provided between the fuel tank and a purge device for purging fuel vapor into the engine intake passage, and when the pressure in the fuel tank exceeds 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 or below a predetermined pressure; and a pressure sensor that detects the internal pressure of the fuel tank, and monitors the detected internal pressure of the fuel tank after the engine is started. (A) slosh detecting means for detecting the occurrence of slosh, which is a jump of fuel in the fuel tank. (B) A counter for counting the number of occurrences of the detected slosh. (G) provisional diagnosis means for provisionally diagnosing that the airtightness on the fuel tank side is normal when the count value of the counter is less than a predetermined value and the detected fuel tank internal pressure after starting the engine shows a predetermined behavior. . (H) a diagnostic canceling means for canceling the diagnostic result of the provisional diagnosis of normality when the count value of the counter becomes equal to or more than the predetermined value. Respectively.

According to such a configuration as the failure diagnosis device, for example, before the count value reaches a predetermined value for determining whether the fuel is full, in the mode shown in FIG. Even if you make a misdiagnosis,
When the count value reaches the above-mentioned predetermined value, the erroneous diagnosis result can be suitably canceled. Therefore, even with the same configuration as the failure diagnosis device, the erroneous diagnosis described above can be suitably avoided.

In the above construction, according to the invention described in claim 6, (i) a predetermined value setting for variably setting a predetermined value to be compared with the count value of the counter according to an elapsed time after starting the engine. Means are further provided. According to this configuration, the provisional diagnosis or the cancellation of the provisionally diagnosed diagnosis is performed based on a more accurate determination of whether or not the fuel is full according to the invention of claim 3. Is performed, and the accuracy of the provisional diagnosis or the cancellation of the provisional diagnosis result naturally increases.

[0025]

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 has an inlet pipe 2 for injecting fuel into the inside, that is, for refueling. The pipe 2 includes an oil supply port 2a at the tip. When refueling the fuel tank 1, a refueling nozzle (not shown) is inserted into the refueling port 2a. 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 are provided corresponding to a plurality of cylinders (not shown) provided on the engine 8. A return line 9 extending from the delivery pipe 6 is connected to the fuel tank 1. By operating the pump 4, the fuel discharged from the pump 4 reaches the delivery pipe 6 through the main line 5 and is distributed to each injector 7. 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, and air purified through the air cleaner 11 is introduced therein. A mixture of fuel and air injected from each injector 7 is supplied to each cylinder of the engine 8 and used for combustion. Surplus fuel without being distributed to each injector 7 in the delivery pipe 6 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 through the exhaust passage 12 to the outside.

The fuel vapor processing apparatus according to this 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 13. The canister 14 contains an adsorbent 15 made of activated carbon or the like. The portion occupied by the adsorbent 15 in the canister 14 and the adsorbent 15
And the spaces 14a and 14b located above and below.

The first air control valve 16 provided on the canister 14 is a diaphragm type check valve. The control valve 16 opens when the internal pressure of the canister 14 is lower than the atmospheric pressure to allow the introduction of outside air (atmospheric pressure) to the canister 14 and prevents the flow of gas in the opposite direction. The air pipe 17 extending from the control valve 16 is connected to the air cleaner 1.
1 is connected in the vicinity. Therefore, outside air purified by the air cleaner 11 is introduced into the canister 14. Second atmospheric control valve 18 provided on canister 14
Consists of a diaphragm check valve. The control valve 18 is opened when the internal pressure of the canister 14 becomes higher than the atmospheric pressure, and allows the gas (internal pressure) to be led out from the canister 14 to the outlet pipe 19, and prevents the gas flow in the opposite direction.

A vapor 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 valve that operates under pressure. This 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. It opens when the above-mentioned valve element operates. 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 higher than the tank-side internal pressure PT to allow the flow of fuel vapor into the canister 14. In addition, the vapor control valve 20 allows gas flow 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.

Purge line 2 extending from canister 14
1 communicates with the surge tank 10a. The canister 14 collects only the fuel component in the fuel vapor introduced through the vapor line 13 and discharges only the gas not containing the fuel component 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 fuel collected by the canister 14 is purged to the intake passage 10 through the purge line 21. A purge control valve 22 provided in the purge line 21 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 element (both not shown), and is supplied with an electric signal to move the valve element.

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 receives a supply of an electric signal and switches communication between ports. One port of the three-way switching valve 23 is connected to the pressure sensor 41, and 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. The pressure sensor 41 is selectively connected to the vapor line 13 or the canister 14 by switching the three-way switching valve 23 as needed. In response to this switching, the pressure sensor 41 selectively detects the tank-side internal pressure PT and the canister-side internal pressure PC.
In this embodiment, when the three-way switching valve 23 is not switched by an electric signal so that the pressure sensor 41 preferentially detects the tank-side internal pressure PT, the three-way switching is performed so that the pressure sensor 41 communicates with the vapor line 13. Valve 2
Switching of 3 is set.

Various sensors 42, 43, 44, 45, 4
6, 47 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.

An electronic control unit (ECU) 51 is a means for controlling each part of the apparatus of this embodiment in a comprehensive manner, as well as a slosh detecting means, a diagnosing means, a counter threshold value (predetermined value) setting means, a diagnosis prohibiting means, Means, temporary diagnosis means, diagnosis cancellation means, etc.

The ECU 51 inputs signals output from the various sensors 41 to 47. In addition, the ECU 51 sets the purge control valve 22 to a required duty ratio D in order to purge an amount of fuel according to the operating state of the engine 8.
A duty signal required for the purge control valve 22 to be controlled by the PG is output. 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 controls the engine 8
The opening degree of the purge control valve 22 is determined according to the operating state of. Generally, when the air-fuel ratio increases, the concentration of CO contained in the exhaust gas of the engine increases. So EC
U51 calculates the value of the purge concentration FGPG based on the value of the oxygen concentration Ox in the exhaust gas detected by the oxygen sensor 46. The ECU 51 determines a duty ratio DPG corresponding to the opening of the purge control valve 22 based on the calculated value,
A duty signal corresponding to the magnitude of the duty ratio DPG is output. That is, the ECU 51 changes the opening degree of the purge control valve 22 based on the duty ratio DPG that is different during the operation of the engine 8 when the vehicle 40 is running and when the vehicle 40 is stopped, and is relatively larger during running than during stopping. Perform duty control.

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 the values .about.47, 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 inputted. The ECU 51 determines the input tank-side internal pressure P
Based on each value of T and the canister-side internal pressure PC, a failure relating to the airtightness of the tank and a failure relating to the airtightness of the canister are individually diagnosed.

In addition, the ECU 51 controls the various sensors 41
Based on the detection values of ~ 47, a failure relating to the functions of the purge control valve 22 and the three-way switching valve 23 is diagnosed. 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 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 receives power supply from the battery 25 mounted on the automobile 40,
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 this embodiment, the backup RAM 55 constitutes a diagnostic data storage unit for storing a diagnostic result regarding a failure as diagnostic data. The timer counter 56 can perform a plurality of timing operations simultaneously. 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 to 47
And the battery 25 is connected to the external input circuit 57. The purge control valve 22, the three-way switching valve 23, and the warning lamp 24 are 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 voltage value VAE of the battery 24, which are input via the external input circuit 57. C
Based on these input values, the PU 52 performs a purge control valve 22 and a three-way switching valve 23 to execute fuel purge and failure diagnosis.
And the warning lamp 24 is controlled.

Next, the specific contents of the processing executed by the ECU 51 will be described. However, in the following, for convenience, the processing executed by the ECU 51 will be described focusing on the operation relating to the airtightness diagnosis on the fuel tank 1 side, which is a main part of the present invention.

As described above, in the fuel tank 1 of the vehicle-mounted engine, a slosh, which is a jump of fuel, may be generated inside the fuel tank 1 depending on the running state of the automobile 40. When such a slosh occurs, the detected tank-side internal pressure (fuel tank internal pressure) PT also fluctuates. In particular, when such a slosh occurs frequently when the fuel is full, the liquid level becomes rough due to the rough surface of the liquid. 13 is repeated, and a disturbance as shown in FIG. 13A is superimposed on the detected tank-side internal pressure PT. If such a disturbance is superimposed on the detected tank-side internal pressure PT, an accurate diagnosis of the airtightness cannot be made.

In this embodiment, the following various processes are executed through the ECU 51. First, 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 internal pressure extraction routine is executed as a time interruption routine every 64 msec.

In this tank internal pressure extraction routine, E
The CU 51 determines in step S100 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 S100 that it is not the time of starting, the ECU 51 determines in step S102 that the detected tank-side internal pressure PT
A / D conversion value PTAD and the previous smoothed value (the value registered in the RAM 54) PTSMi for the same pressure PT
Based on −1, an averaging operation PTSMi = PTSMi−1 + (PTAD−PTSMi−1) / 4 (1) is executed to obtain a new averaging value PTSMi, and the obtained averaging value PTSMi is used in the RAM 54. The update value PTSMi-1 is updated.

In the tank internal pressure extraction routine, such processing is repeatedly executed every 64 msec. ECU
Reference numeral 51 also manages the presence / absence of the slosh and the number of times the slosh has occurred through the slosh determination routine shown in FIG. This slosh determination routine is executed as a time interruption routine every one second.

In this slosh determination routine, E
The CU 51 determines in step S200 whether or not the engine 8 has been started.
, The tank-side internal pressure PT registered in the RAM 54
Is registered in another area in the RAM 54 as a slosh-determined average value PTW for the same pressure PT.

On the other hand, if it is determined in step S200 that it is not the time of starting, the ECU 51 determines in step S202 that the smoothed values PTSM and PT
It is determined whether or not the absolute value of the difference between W is equal to or greater than “1.25 mmHg”, that is, whether or not | PTSM−PTW | ≧ 1.25 mmHg (2). Then, as a result, if the relationship of the expression (2) is satisfied, it is determined that slosh has occurred, the slosh counter CPMSK is incremented in step S203, and the process proceeds to step S204. If the relationship of the above expression (2) is not satisfied, it is determined that slosh has not occurred, and the process proceeds to step S204 without incrementing the slosh counter CPMSK.

In step S204, the RAM
54 and the same pressure P as the smoothing value PTSM for the tank side internal pressure PT registered in
A smoothing operation PTWi = PTWi-1 + (PTSM-PTWi-1) / 8 is executed based on the smoothed value (slosh-determined smoothed value) PTWi-1 of T every 1 second to obtain a new value. The slosh-determined average value PTWi is obtained from the RAM 54 based on the obtained average value PTWi.
The average value PTWi-1 is updated.

In the slosh determination routine, such a process is repeatedly executed every one second. ECU 51
Further, in parallel with these processes, a process related to the airtightness diagnosis on the fuel tank 1 side is executed.

In this embodiment, the airtightness of the fuel tank 1 is diagnosed in the manner illustrated in FIG. The outline is described below. When the engine 8 is started at a low temperature, the tank-side internal pressure (fuel tank internal pressure) PT is temporarily reduced to a negative pressure as shown by a solid line in FIG. Become. Normally, the pressure becomes the lowest in about 5 minutes after starting. Thereafter, the pressure PT gradually increases with the elapse of time as the fuel temperature rises due to the recirculation of surplus fuel and the like. 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 the 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 the above characteristics of the tank-side internal pressure PT, the pressure PT is set within a predetermined time after the engine 8 is started (for example, within about 20 minutes after the start), as shown in FIG. When the pressure is equal to or lower than the negative pressure PT2 or equal to or higher than the predetermined positive pressure PT1, it is diagnosed as “normal”, and otherwise, as “abnormal”. Here, these judgment values PT1
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 mm
Aq) ”and the determination value PT2 is“ atmospheric pressure−
A negative pressure of about 0.3 KPa (30 mmAq) is set.

At the same time, the number of slosh occurrences (count value of the slosh counter CPMSK) managed through the above-described slosh determination routine is monitored, and when this number exceeds a predetermined number (for example, “30”), the fuel tank 1 It is determined that the fuel is full and the diagnosis is interrupted.

Further, when the fuel is full, even if the fuel tank 1 or the vapor line 13 has a hole having a diameter of about 1 mm, a negative pressure is generated in the fuel tank 1 due to fuel consumption.
In view of the possibility of erroneous diagnosis as “normal” before the number of slosh occurrences reaches the predetermined number, in particular, (1) the number of slosh occurrences (the value of the counter CPMSK)
Is greater than or equal to a first predetermined value CR (for example, “10”), the diagnosis of “normal” is prohibited. (2) Thereafter, the number of slosh occurrences (counter CPMS
If the value of K is equal to or more than a second predetermined value CB (= full tank determination value, for example, “30”), the diagnosis of “abnormal” is also prohibited. (3) Even if the diagnosis of “normal” is made once, the slosh occurrence count (counter CPM
If the SK value is equal to or greater than the first predetermined value CR, the diagnosis result is canceled. Such an algorithm is also introduced.

FIG. 6 shows an example of a diagnostic routine for diagnosing the airtightness of the fuel tank 1 based on such an algorithm. This diagnosis routine is also executed through the ECU 51 as a time interruption routine at regular intervals, similarly to the tank internal pressure extraction routine and the slosh determination routine. Note that 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 S300, 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 is not completed, the ECU 51
Resets the timer value t of the timer for measuring the time after the engine is started in step S301 (t ← 0), and sets a flag KD indicating whether or not the diagnosis is completed in step S302 to indicate that the diagnosis is not completed. Set "0" to indicate (K
D ← 0), the routine is once exited.

On the other hand, if the start of the engine 8 has been completed, the ECU 51 determines in step S310 that the flag KD has been set.
In step S311 the timer value t is incremented (step S311) on condition that "1" indicating the end of the diagnosis is not set in this state, that is, on condition that "KDＫ1" is satisfied. t ← t + 1).

In step S312, the ECU 51 that has incremented the timer value t in step S312 determines that the timer value t
Is determined to have 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 S313.

When the pressure value PT is read, the ECU 51
In order to execute the airtightness diagnosis on the fuel tank 1 side in the mode illustrated in FIG. 5, steps S314 and S315
It is determined whether or not the pressure value PT is equal to or less than the determination value PT2 and whether or not the pressure value PT is equal to or greater than the determination value PT1.

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 S318 that the count value of the slosh counter CPMSK incremented through the above-described slosh determination routine (FIG. 4) is less than the first predetermined value CR ("10"). In step S319, “0” indicating normality is set in the diagnostic flag FX (FX ← 0). In this case, the flag KD is set in the next step S320.
Is set to “1” indicating the end of diagnosis (KD ←
1), once exit from the routine. Note that the above step S3
If it is determined in step 18 that the count value of the slosh counter CPMSK is equal to or greater than the first predetermined value CR ("10"), the normality is not diagnosed and the above-described step is performed. After the flag KD is set to “0” indicating the end of the diagnosis through S302, (KD ←
0), the routine is once exited. When the fuel is full, even if the fuel tank 1 or the vapor line 13 has a hole with a diameter of about 1 mm, a negative pressure is generated in the fuel tank 1 due to fuel consumption, and before the number of slosh occurrences reaches a predetermined number. There is a possibility of erroneous diagnosis as “normal”. It is as described above that consideration is given to such concerns.

On the other hand, as a result of the diagnosis of the pressure value PT, one of the following: the pressure value PT is higher than the determination value PT2; and the pressure value PT is lower than the determination value PT1. Is confirmed, the ECU 51 determines that the count value of the slosh counter CPMSK is equal to the second predetermined value C.
On the condition that it is determined in step S316 that it is less than B (“30”), in step S317,
The diagnostic flag FX is set to "1" indicating an abnormality (FX ← 1), and the routine is once exited. Also in this case, in step S316, the count value of the slosh counter CPMSK is changed to the second predetermined value CB.
("30") or more,
Without performing the diagnosis of the abnormality, the above-described step S30 is performed.
2, the flag KD indicates "0" indicating that diagnosis has not been completed.
Is set (KD ← 0), and the routine once exits. This is because the tank-side internal pressure P detected as described above when slosh occurs.
T also fluctuates, and particularly when such slosh occurs frequently when the fuel is full, the vapor line 13 is repeatedly closed and released due to the rough surface of the liquid, and the detected pressure value PT is changed to the above-described pressure value PT. The disturbance as shown in FIG. 13A is superimposed. If such a disturbance is superimposed on the detected tank-side internal pressure PT, an accurate diagnosis of the airtightness cannot be made. This is a consideration for such concerns.

Thereafter, if it is determined in step S312 that the timer value t has reached the predetermined value t0 by repeatedly executing the diagnostic routine, step S312 is executed.
At step 20, "1" indicating the end of the diagnosis is set in the flag KD (KD ← 1), and the routine exits.

In the diagnosis routine, even if it is determined in step S310 that "1" indicating the end of the diagnosis is set in the flag KD,
That is, even if the flag KD is set to "KD = 1" due to a normal diagnosis or the like, the count value of the slosh counter CPMSK is increased to the first predetermined value CR in step S330. When it is determined that the value is (“10”) or more, the ECU 51 cancels the diagnosis result. In this case as well, the flag KD is set to “0” indicating the end of the diagnosis through step S302, and then (KD) ← 0) Exit from this routine once. When the fuel is full, even if the fuel tank 1 or the vapor line 13 has a hole having a diameter of about 1 mm as described above, a negative pressure is generated in the fuel tank 1 due to fuel consumption, and the number of slosh occurrences becomes a predetermined number. May be erroneously diagnosed as “normal” before the threshold is reached. Such concerns will be appropriately eliminated.

Incidentally, in the failure diagnosis apparatus, the normal (FX = 0) or abnormal (FX =
The diagnosis result of 1) is stored in the backup RAM 55.
Registered for If the registered diagnosis result indicates that the diagnosis is abnormal (FX = 1), the ECU 51
Controls the lighting of the warning lamp 24 and informs the driver of this.

As described above, in this diagnostic routine, FIG.
When diagnosing the airtightness of the fuel tank 1 side exemplified in the above, it is determined in the above-described manner that the fuel is full, the diagnostic operation is interrupted, and the diagnosis that the fuel tank is normal when the fuel is full is limited. Even if a normal diagnosis is made, the result of the diagnosis is canceled when the number of occurrences of the slosh reaches the limited number.

For this reason, according to the failure diagnosis apparatus according to the embodiment, (a) In a situation in which proper airtightness diagnosis is not performed on the fuel tank 1 side, such as when the fuel is full, in which slosh occurs frequently. By prohibiting the diagnosis operation, erroneous diagnosis is suppressed. (B) In particular, the allowable value CR for the number of slosh occurrences that can be diagnosed as normal is set to a value smaller than the allowable value CB for the number of slosh occurrences that can be diagnosed as abnormal. As a result, it is difficult to at least make a diagnosis of “normal”. Therefore, when the tank is full, the possibility of erroneous diagnosis that the airtightness is normal in spite of the airtightness abnormality is also suitably suppressed. (C) Further, even if the number of occurrences of the slosh is erroneously diagnosed as "normal" before reaching the predetermined number for determining whether the fuel is full, the number of occurrences reaches the predetermined number thereafter. Thus, the erroneous diagnosis result is canceled. This also greatly suppresses the possibility that an erroneous diagnosis that the airtightness is normal when the tank is full despite abnormal airtightness is made. Excellent effects can be achieved.

In this embodiment, in the diagnosis routine, the normal diagnosis restriction process in step S318 and the diagnosis result cancellation process in step S330 are performed together.

However, if the above-described erroneous diagnosis of “normal” is sufficiently avoided by the normal diagnosis restriction process in step S318, the above-described step S330 is performed.
May be omitted.

Conversely, if the erroneous diagnosis of “normal” is sufficiently avoided by the cancellation processing of the diagnosis result in step S330, the normal diagnosis restriction processing in step S318 is omitted. It can also be a diagnostic structure.

In this embodiment, the allowable value (first predetermined value) CR for the number of occurrences of slosh at which the above-mentioned normal state can be diagnosed is set to "10", and the abnormality is judged to be abnormal. The allowable value (second predetermined value) CB for the number of occurrences of the slosh that can be diagnosed is set to "30" to monitor whether or not the fuel is full. However, these first and second predetermined values CR and CB
As long as the relationship such as the first predetermined value CR <the second predetermined value CB is maintained, the specific values are not limited to the above example and are arbitrary.

Incidentally, the frequency of occurrence of the slosh generally changes according to the degree of fullness of the fuel in the fuel tank 1. Then, the degree of fullness of the fuel also changes according to the elapsed time t after the engine is started due to the consumption of the fuel. The solid line shown in FIG. 7 is the slosh counter CPM.
The relationship between the number of slosh occurrences and the post-start time t is shown as the transition of the SK count value.

Therefore, as also shown by a dashed line in FIG. 7, a threshold value (the above-mentioned predetermined value CR) for the count value of the counter CPMSK in accordance with the elapsed time t after the engine is started.
Alternatively, the diagnostic structure may be configured such that CB) is variably set, and when the count value is equal to or greater than the variably set threshold value, it is determined that the fuel is full and the diagnostic operation is prohibited.

That is, in this case, the ECU 51 sets the threshold values CR and C with respect to the count value of the counter CPMSK.
For B, for example, maps such as those shown in FIGS. 8A and 8B are stored in the ROM 53 or the backup RAM 55, and as the time t after the start elapses, the values of the corresponding thresholds CR and CB respectively correspond to B. In step S318 and step S3 in the diagnosis routine (FIG. 6).
16, and used for comparison with the count value in step S330.

By adopting such a diagnostic structure as the failure diagnostic device, it is possible to determine with higher accuracy whether or not the fuel is full based on the count value, As a result, the above-described erroneous diagnosis is more difficult to be performed.

In this case, the threshold value for the count value may be any one of CR and CB, and the variable mode with the elapse of the time t after the start is linear with respect to the time t after the start. No need.

In the above-described embodiment, the airtightness of the fuel tank 1 is diagnosed in the mode illustrated in FIG. The diagnostic method illustrated in FIG. 9 may be employed.

That is, in the diagnostic method illustrated in FIG. 5, the presence or absence of airtightness is diagnosed based on the absolute value of the tank-side internal pressure (fuel tank internal pressure) PT, which is illustrated in FIG. In the diagnosis method, the lowest pressure PT at which the tank-side internal pressure PT has reached within a predetermined time after the engine is started.
When the difference ΔPT between min and the highest pressure PTmax is equal to or greater than the determination value ΔPTO (for example, about 0.6 KPa), it is diagnosed as normal, and when the difference ΔPT is less than the determination value ΔPTO, abnormality is determined.

FIG. 10 shows an example of a diagnostic routine for diagnosing the airtightness of the fuel tank 1 based on such a diagnostic method. In the diagnostic routine shown in FIG. 10, the number of slosh occurrences (the count value of the slosh counter CPMSK) managed through the slosh determination routine (FIG. 4) is monitored, and the number is monitored by a predetermined number (for example, "3").
0 ") or more, determine that the fuel in the fuel tank 1 is full and interrupt the diagnosis. When the fuel is full, even if the fuel tank 1 or the vapor line 13 has a hole with a diameter of about 1 mm, a negative pressure is generated in the fuel tank 1 due to fuel consumption, and before the slosh occurrence number reaches a predetermined number. (1) Slosh occurrence count (value of counter CPMSK)
Is greater than or equal to a first predetermined value CR (for example, “10”), the diagnosis of “normal” is prohibited. (2) Thereafter, the number of slosh occurrences (counter CPMS
If the value of K is equal to or more than a second predetermined value CB (= full tank determination value, for example, “30”), the diagnosis of “abnormal” is also prohibited. (3) Even if the diagnosis of “normal” is made once, the slosh occurrence count (counter CPM
If the SK value is equal to or greater than the first predetermined value CR, the diagnosis result is canceled. That the algorithm is also introduced. And so on are the same as in the case of the diagnostic routine illustrated in FIG.

The diagnostic routine shown in FIG. 10 is also a prerequisite thereof. The abnormality of the diagnostic system including the pressure sensor 41 is not 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. The processing is executed through the ECU 51 as a time interruption routine at predetermined time intervals on condition that all of the above conditions are satisfied.

The diagnostic routine shown in FIG. 10 will be described in detail below, although it partially overlaps with the diagnostic routine shown in FIG. In this diagnostic routine, the ECU
First, at step S400, it is determined whether or not the start of the engine 8 has been completed. Also here, the ECU 51 determines that the start of the engine 8 has been completed when the engine rotation speed NE becomes equal to or higher than a predetermined value (for example, 400 rpm). If the start of the engine 8 is not completed, EC
U51 resets the timer value t of the timer for measuring the time after engine start in step S401 (t ← 0),
In step S402, a flag KD indicating whether or not the diagnosis has been completed is set to "0" indicating that the diagnosis has not been completed (KD ← 0), and the routine once exits.

On the other hand, if the start of the engine 8 has been completed, the ECU 51 determines in step S410 that the flag KD
In step S411, the timer value t is incremented (step S411) on the condition that "1" indicating the end of the diagnosis is not set, that is, on condition that "KD「 1 ". t ← t + 1).

The ECU 51 that has thus incremented the timer value t then proceeds to step S412 where the timer value t is incremented.
Is determined to have 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 S413.

When the pressure value PT is read, the ECU 51
In order to execute the airtightness diagnosis on the fuel tank 1 side in the mode illustrated in FIG. 9, steps S414 and S415
In, the minimum value PTmin of the same pressure value PT is updated,
Further, in steps S416 and S417, the maximum value PTmax of the pressure value PT is updated, and the routine once exits.

Thereafter, when it is determined in step S412 that the timer value t has reached the predetermined value t0,
The ECU 51 determines in step S418 that the maximum value P
It is determined whether or not the difference (ΔPT) between Tmax and the minimum value PTmin is equal to or greater than the determination value ΔPTO, that is, whether or not the relationship of PTmax−PTmin ≧ ΔPTO (4) is satisfied.

When it is determined that the relationship of the expression (4) is satisfied, the ECU 51 determines whether the count value of the slosh counter CPMSK incremented through the slosh determination routine (FIG. 4) is equal to the aforementioned value. On condition that it is determined in step S419 that the value is less than the first predetermined value CR ("10"), "0" indicating normality is set in the diagnostic flag FX in step S420 ( FX ← 0). And
In the next step S421, "1" indicating the end of the diagnosis is set in the flag KD (KD ← 1), and then the routine exits once. If it is determined in step S419 that the count value of the slosh counter CPMSK is equal to or greater than the first predetermined value CR ("10"), the normal diagnosis is not performed. In step S402, the flag KD is set to "0" indicating that the diagnosis has not been completed (KD ← 0), and the process once exits. When the fuel is full, even if the fuel tank 1 or the vapor line 13 has a hole with a diameter of about 1 mm, a negative pressure is generated in the fuel tank 1 due to fuel consumption, and before the number of slosh occurrences reaches a predetermined number. There is a possibility of erroneous diagnosis as “normal”. This is the same as the diagnosis routine shown in FIG.

On the other hand, if it is determined that the relationship of the expression (4) is not satisfied, the ECU 51 determines that the relationship of the expression (4) is not satisfied.
Is determined in step S422 to be smaller than the second predetermined value CB ("30") in step S423, the diagnostic flag FX is determined in step S423.
Is set to "1" indicating that there is an abnormality (FX ←
1). Also in this case, after the flag KD is set to “1” indicating the end of the diagnosis in step S421 (K
D ← 1), the routine is temporarily exited. In this case, if it is determined in step S422 that the count value of the slosh counter CPMSK is equal to or greater than the second predetermined value CB (“30”), the diagnosis of the abnormality is made. Without performing the process, the flag KD is set to “0” indicating that the diagnosis is not completed through the step S402 (KD ← 0), and the process once exits. This is also due to the aforementioned tank-side internal pressure P detected when slosh occurs.
T also fluctuates, and particularly when such slosh occurs frequently when the fuel is full, the vapor line 13 is repeatedly closed and released due to the rough surface of the liquid, and the detected pressure value PT is changed to the above-described pressure value PT. The disturbance as shown in FIG. 13A is superimposed. If such a disturbance is superimposed on the detected tank-side internal pressure PT, an accurate diagnosis of the airtightness cannot be made. This is a consideration for such concerns.

On the other hand, even if it is determined in step S410 that "1" indicating the end of the diagnosis has been set in the flag KD, that is, the normal diagnosis is performed once. When the flag KD is "KD
= 1 ”, the count value of the slosh counter CPMSK is set to the first value in step S430.
Is determined to be equal to or greater than the predetermined value CR ("10"), the ECU 51 cancels the diagnosis result, and in this case also sets "0" to the flag KD through step S402 to indicate that the diagnosis has not been completed. Above (KD ← 0), the routine exits. When the fuel is full, even if the fuel tank 1 or the vapor line 13 has a hole having a diameter of about 1 mm as described above, a negative pressure is generated in the fuel tank 1 due to fuel consumption, and the number of slosh occurrences becomes a predetermined number. May be erroneously diagnosed as “normal” before the threshold is reached. Such a concern is suitably eliminated, as in the case of the diagnosis routine shown in FIG.

As described above, even in the diagnosis routine shown in FIG. 10, when the airtightness of the fuel tank 1 illustrated in FIG. 9 is diagnosed, the fullness of the fuel is determined in the above-described manner, and the diagnosis operation is performed. Suspended and also limits the normal diagnosis when the tank is full, and when the normal slosh frequency reaches the limited number of times even if the normal diagnosis is made, the same diagnostic result is obtained. I am trying to cancel it.

Therefore, according to such an embodiment, the excellent effects shown in the above (a) to (c) of the previous embodiment can be obtained. If the variable threshold value structure illustrated in FIG. 8 is also adopted, (d) the determination as to whether or not the fuel is full based on the count value can be performed with higher accuracy. The above-described erroneous diagnosis is more difficult to be performed. Such effects can also be achieved.

In the diagnosis routine illustrated in FIG. 10, the normal diagnosis restriction processing in step S419 and the diagnosis result cancellation processing in step S430 are performed together. If the erroneous diagnosis of “normal” described above is sufficiently avoided by the normal diagnosis restriction process, the process of canceling the diagnosis result in step S430 may be omitted. Conversely, if the erroneous diagnosis indicating “normal” is sufficiently avoided by the process of canceling the diagnosis result in step S430, the diagnosis structure is omitted from the restriction process of normal diagnosis in step S419. You can also.

The method of diagnosing the airtightness on the fuel tank 1 side is arbitrary other than the method illustrated in FIG. 5 or FIG. 9, and may be, for example, the time of the tank-side internal pressure (fuel tank internal pressure) PT. A method of diagnosing the airtightness of the fuel tank 1 on the basis of the integrated value may be appropriately adopted. Regardless of which diagnostic method is used, the point is that, as described above, the number of occurrences of slosh is monitored, and when this number exceeds a predetermined number, it is determined that the fuel in the fuel tank 1 is full and the same diagnosis is performed. Interrupt. At that time, when the number of times of slosh occurrence becomes equal to or more than the first predetermined value CR which is smaller, the diagnosis of "normal" is first prohibited. After that, if the number of slosh occurrences becomes equal to or more than a second predetermined value CB (for example, a full tank determination value), the diagnosis of “abnormal” is also prohibited. -Even if the diagnosis of "normal" is made once, the number of occurrences of the slosh is, for example, the first
When the predetermined value CR becomes equal to or more than the predetermined value CR, the diagnosis result is canceled. In some cases, the first and second predetermined values CR and CB, or one of them, is variably set according to the time t after the engine 8 is started. By introducing such an algorithm together, a desired effect according to the above embodiment can be obtained.

[0093]

As described above, according to the present invention, the allowable value for the number of occurrences of slosh that can be diagnosed as normal airtightness on the fuel tank side is abnormal when the airtightness on the fuel tank side is abnormal. The value is set to a value smaller than the allowable value for the number of occurrences of the slosh that can be diagnosed. Therefore, even if the diagnosis is interrupted when it is determined that the fuel is full based on the number of slosh occurrences, it is difficult to perform at least a "normal" diagnosis and, consequently, a "normal" diagnosis. Erroneous diagnosis is hardly performed.

Further, according to the present invention, the threshold value for interrupting the diagnosis for the number of occurrences of the slosh is variably set in accordance with the elapsed time after the engine is started, that is, in accordance with the degree of fuel fullness. For this reason, it is possible to determine with higher accuracy whether or not the fuel is full based on the number of occurrences of the slosh, and it is also difficult to make an erroneous diagnosis.

Further, according to the present invention, even if the number of occurrences of the slosh is erroneously diagnosed as "normal" before reaching the predetermined number for determining whether the fuel is full, the number of occurrences of the slosh is thereafter reduced to When the predetermined number of times is reached, the erroneous diagnosis result can be suitably canceled. Therefore, also in this case, erroneous diagnosis when the fuel is full can be suitably avoided.

[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 flowchart showing a tank internal pressure extraction routine of the embodiment.

FIG. 4 is a flowchart showing a slosh determination routine of the embodiment.

FIG. 5 is a graph showing an example of a method for diagnosing airtightness on the tank side.

FIG. 6 is an exemplary flowchart illustrating an example of a diagnostic routine according to the embodiment.

FIG. 7 is a time chart showing another example of the determination of the full fuel level.

FIG. 8 is a schematic diagram showing an example of a map of a counter threshold used for the full tank determination.

FIG. 9 is a graph showing another example of a method for diagnosing airtightness on the tank side.

FIG. 10 is an exemplary flowchart illustrating another example of the diagnosis routine of the 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.

FIG. 13 is a time chart showing a full tank determination mode based on the number of times of slosh.

[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, 47: a vehicle speed sensor, 51: an electronic control unit (ECU).

Claims (6)

[Claims] The fuel tank is provided between a purge device for purging fuel vapor into an engine intake passage and a fuel tank, and is opened when the pressure in the fuel tank exceeds a predetermined pressure higher than the atmospheric pressure. And a pressure sensor for detecting the fuel tank internal pressure, and monitors the detected fuel tank internal pressure after starting the engine to improve the airtightness of the fuel tank side. In the failure diagnosis device for a fuel vapor processing device to be diagnosed, slosh detection means for detecting the occurrence of slosh, which is a jump of fuel in the fuel tank, a counter for counting the number of occurrences of the detected slosh, First diagnosing means for diagnosing whether or not the airtightness on the fuel tank side is normal on condition that the count value is less than a first predetermined value; A second diagnosing means for diagnosing whether the airtightness on the fuel tank side is abnormal on condition that the count value of the fuel tank is less than a second predetermined value larger than the first predetermined value. A failure diagnosis device for a fuel vapor treatment device, comprising: 2. The failure diagnosis device for a fuel vapor processing device according to claim 1, wherein the second predetermined value corresponds to the number of slosh occurrences for determining that the fuel in the fuel tank is full. A failure diagnosis device for a fuel vapor processing device, wherein the failure diagnosis device is set to a value obtained by the following method. 3. The fuel tank is provided between a purge device for purging fuel vapor into an engine intake passage and a fuel tank. The valve is opened when the pressure in the fuel tank exceeds a predetermined pressure higher than the atmospheric pressure. And a pressure sensor for detecting the fuel tank internal pressure, and monitors the detected fuel tank internal pressure after starting the engine to improve the airtightness of the fuel tank side. In the failure diagnosis device for a fuel vapor processing device to be diagnosed, slosh detection means for detecting occurrence of slosh, which is a jump of fuel in the fuel tank, a counter for counting the number of times of the detected slosh, and after the engine is started. Threshold setting means for variably setting a threshold value for the count value of the counter according to the elapsed time of the counter; Diagnosis prohibition means for prohibiting the diagnosis of whether the airtightness on the fuel tank side is normal or abnormal on condition that the airtightness on the fuel tank side is equal to or greater than a threshold value. apparatus. 4. The fuel cell system according to claim 1, wherein said threshold value setting means includes a first threshold value which is referred to when diagnosing whether the airtightness on said fuel tank side is normal, and said first threshold value being larger than said first threshold value. 4. The failure diagnosis device for a fuel vapor processing device according to claim 3, wherein the second threshold value referred to when diagnosing whether the airtightness of the side is abnormal is set variably. 5. A fuel tank is provided between a purge device for purging fuel vapor into an engine intake passage and a fuel tank. The valve is opened when the pressure in the fuel tank exceeds a predetermined pressure higher than the atmospheric pressure. And a pressure sensor for detecting the fuel tank internal pressure, and monitors the detected fuel tank internal pressure after starting the engine to improve the airtightness of the fuel tank side. In the failure diagnosis device for a fuel vapor processing device to be diagnosed, slosh detection means for detecting the occurrence of slosh, which is a jump of fuel in the fuel tank, a counter for counting the number of occurrences of the detected slosh, When the count value is less than a predetermined value and the detected pressure in the fuel tank after starting the engine shows a predetermined behavior, the airtightness on the fuel tank side is correct. And a diagnosis canceling means for canceling the diagnosis result of the provisional diagnosis when the count value of the counter is equal to or more than the predetermined value. Diagnostic device for a fuel vapor treatment device. 6. A failure diagnosis apparatus for a fuel vapor processing apparatus according to claim 5, further comprising a predetermined value setting means for variably setting a predetermined value to be compared with a count value of said counter in accordance with an elapsed time after starting the engine. A failure diagnosis device for a fuel vapor treatment device, comprising: