JP5056580B2 - Leak diagnostic device and leak diagnostic method for evaporative fuel barge passage of internal combustion engine for vehicle - Google Patents

Description

  The present invention relates to a leakage diagnosis of an evaporated fuel barge passage for diagnosing whether or not there is a leak in an evaporated fuel purge passage evaporating from a fuel tank of a vehicle.

  Regarding the diagnosis of whether there is a leak in the purge passage of the evaporated fuel evaporating from the fuel tank of the vehicle, the legislation on volatile organic compounds (VOC) in California, USA, is the so-called 0.04 inch leak diagnosis, 0.02 inch leak diagnosis, And gross leak judgment. The 0.04 inch leak diagnosis is a diagnosis method for detecting a leak equivalent to the case where a hole corresponding to a 0.04 inch diameter is provided in the purge passage. The 0.02 inch leak diagnosis is also a hole corresponding to a 0.02 inch diameter. This is a diagnostic method for detecting a leak equivalent to the case where there is an error. Gross leak determination is a diagnostic method for determining the presence or absence of a large amount of leak from an aspect in which the pressure in the purge passage of evaporated fuel increases from zero as the fuel evaporates.

  Regarding the leak diagnosis method, a method of diagnosing the presence or absence of the above three types of leaks (hereinafter referred to as A) by depressurizing the fuel tank using the suction negative pressure of the internal combustion engine while the vehicle is running and recovering from the negative pressure of the fuel tank. And a method of performing 0.02 inch leak diagnosis (hereinafter abbreviated as B method diagnosis) by utilizing the negative pressure of the fuel tank accompanying a drop in fuel temperature after the vehicle stops. ing.

  Patent Document 1 discloses a method of A method diagnosis performed during driving of a vehicle and a method of B method diagnosis performed after the vehicle stops.

  Patent Document 2 and Patent Document 3 disclose a method of B-system diagnosis performed after the vehicle stops.

The above-mentioned laws and regulations require that the presence of a leak be determined and displayed on a warning light when a leak is detected on two consecutive trips of the vehicle, regardless of the diagnostic method.
JP 2007-092589 A JP 2005-344540 A JP 2005-344541 A

  According to the A method diagnosis method, it is possible to diagnose a leak including the leak level, that is, how much leak exists. The A method diagnosis method is a preferable diagnosis method in that respect, but the diagnosis condition is There is a problem that the probability of establishment is low.

  On the other hand, in the B method diagnosis method, the probability that the diagnosis condition is satisfied is high, but the leak level cannot be determined. In addition, it is necessary to make a determination while the vehicle is stopped, and battery power is consumed during the determination period, so the burden on the battery is large. Therefore, to increase the diagnosis frequency, the battery capacity must be increased.

  Accordingly, an object of the present invention is to increase the chance of determining a leak level in leak diagnosis of an evaporated fuel barge passage of an internal combustion engine for a vehicle.

In order to achieve the above object, according to the present invention, a leak diagnosis apparatus for an evaporative fuel barge passage of an internal combustion engine for a vehicle uses a first leak diagnosis for determining whether or not there is a leak including a leak level determination every time the vehicle travels. Means for executing the second leak diagnosis for determining whether or not there is a leak of a specific level or more for each stop of the vehicle, and continuously detecting the same level of leak twice in the first leak diagnosis In this case, the first determination means for determining the leak level according to the first leak diagnosis result detected twice in succession, and the leak immediately before or immediately after the leak is detected in the first leak diagnosis. If the leakage over a specific level in second leakage diagnosis is detected, a second probability to determine the leak level based on the level of the detected leak in the first leak diagnosis It is provided with a means, a.

According to another aspect of the present invention, in the method for diagnosing an evaporative fuel barge passage of an internal combustion engine for a vehicle, the first leak diagnosis for determining the presence or absence of a leak including the determination of a leak level for each travel of the vehicle is performed. only the presence or absence of a leak by executing the second leak diagnosis determines for each vehicle stop, when detecting twice consecutively leakage same level in the first leak diagnosis, the detected twice in succession The leak level is determined according to the result of the first leak diagnosis, and when a leak is detected in the first leak diagnosis and a leak of a specific level or more is detected in the second leak diagnosis immediately before or immediately after the first leak diagnosis, The leak level is determined based on the leak level detected in the leak diagnosis of 1 .

  Based on the established first leak diagnosis result and the result of the second leak diagnosis immediately before or immediately after the established first leak diagnosis, the second determining means determines the leak level. Compared with the case where the leak level is determined only by this, the determination frequency of the leak level can be increased.

  FIG. 1 shows the configuration of an evaporative fuel purge system for a vehicle to which the present invention is applied.

  The evaporative fuel purge system refers to a system that purges the evaporated gas generated in the fuel tank 2 of the vehicle to the intake pipe 22 of the internal combustion engine 21. Among these, the section subjected to the leak diagnosis is a section from the fuel tank 2 to the purge valve 7. This section is referred to as an evaporated fuel barge passage 1 as a leak diagnosis target.

  The evaporated fuel barge passage 1 includes a fuel tank 2, a vent line 3 connected to the fuel tank 2, and a canister 4 connected to the vent line 3. The canister 4 contains an adsorbent 4a such as activated carbon that adsorbs the evaporated fuel. The evaporated fuel gas flows in the canister 4 along a U-shaped path passing through the adsorbent 4a. The evaporated fuel gas is released into the air from the atmosphere opening passage 11 connected to the canister 4 after the adsorbent 4a has adsorbed the fuel.

  The atmosphere open passage 11 is provided with a vent cut valve 5 composed of a normally open type electromagnetic valve. The vent cut valve 5 has a function of selectively sealing the diagnosis target section 1 as described later.

  The fuel in the fuel tank 2 is injected from the fuel injection valve 23 provided in the internal combustion engine 21 toward the intake port. Fresh air corresponding to the opening degree of the throttle 27 is sucked into the intake pipe 22 and supplied to the combustion chamber 24 of the internal combustion engine 21 as an air-fuel mixture mixed with the fuel injected from the fuel injection valve 23. After the air-fuel mixture burns in the combustion chamber 24, it is discharged to the exhaust pipe 25 as exhaust gas. The exhaust gas is purified by the catalyst 26 provided in the middle of the exhaust pipe 25 and then released into the atmosphere.

  The canister 4 is connected to the intake pipe 22 by a purge passage 6 in order to purge the evaporated fuel adsorbed by the adsorbent 4 a into the intake pipe 22. The purge passage 6 is connected to the intake pipe 22 downstream of the throttle 27. The purge passage 6 is provided with a purge valve 7 constituted by a normally closed electromagnetic valve.

  The leak diagnostic apparatus according to the present invention detects a pressure sensor 8 for detecting the pressure in the evaporated fuel barge passage 1 from the fuel tank 2 to the purge valve 7, a temperature sensor 9 for detecting the temperature in the fuel tank 2, and an outside air temperature. An outside air temperature sensor 13.

  The leak diagnosis apparatus includes a controller 10 that performs a leak diagnosis of the evaporated fuel barge passage 1. The controller 10 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a nonvolatile memory, and an input / output interface (I / O interface). It is also possible to configure the controller with a plurality of microcomputers.

  The controller 10 controls the opening and closing of the vent cut valve 5 when the internal combustion engine 21 is stopped. Whether or not there is a leak from the evaporated fuel barge passage 1 based on the outputs of the pressure sensor 8, the temperature sensor 9, and the outside air temperature sensor 13. Diagnose whether or not.

  FIG. 2 shows an algorithm for leak diagnosis executed by the controller 10.

  First, the controller 10 executes the A method diagnosis in step S1 while the vehicle is traveling. As described above, the A method diagnosis includes 0.04 inch leak diagnosis, 0.02 inch leak diagnosis, and gross leak determination. Since each diagnosis method is well-known, the detailed description is abbreviate | omitted.

  When the vehicle stops driving, the controller 10 determines in step S2 whether the A method diagnosis has been completed. If the A method diagnosis is completed, the controller 10 ends the process as it is. If the A method diagnosis is not completed, the B method diagnosis is executed in step S3.

  By this basic process, the B method diagnosis is effective only when the A method diagnosis is not completed during traveling. In order to perform this basic process, the controller 10 stores the diagnosis results in the nonvolatile memory for the A diagnosis and the B diagnosis until the next diagnosis.

  When the A method diagnosis in step S1 is not completed, the controller 10 performs a leak level diagnosis by combining the result of the B method diagnosis with the result obtained in the A method diagnosis in the B method diagnosis executed in step S3. Do.

  FIG. 3 shows an example of a diagnostic result obtained by executing the above diagnostic routine by the controller 10.

  As shown in the figure, in the first trip in which the controller 10 cannot complete the A method diagnosis during traveling, the B method diagnosis is performed while the vehicle is stopped. In a second trip subsequent to the first trip, the controller 10 completes the A-type diagnosis while the vehicle is traveling. Therefore, the controller 10 does not perform leak diagnosis while the second trip is stopped. In the third trip subsequent to the second trip, the controller 10 cannot complete the A method diagnosis while the vehicle is traveling. Therefore, in the third trip, the B-type diagnosis is performed while the vehicle is stopped.

  In accordance with the above-mentioned laws and regulations, the leak diagnosis device displays a warning light when a leak is detected in two consecutive trips of the vehicle. Here, the diagnosis completion frequency of the A method diagnosis performed during traveling is set to 1/3. According to the algorithm of FIG. 2, when the A method diagnosis is not completed, the B method diagnosis is performed during the subsequent vehicle stop.

  In this case, a combination of diagnostic patterns over two trips is as follows.

(1) A-type diagnosis is completed in two trips in succession: 1/9
(2) Method A diagnosis is completed on one trip and not completed on the other trip: 4/9
(3) A method diagnosis is not completed in either of two trips: 4/9
In the case of (3), the B system diagnosis is performed. In the case (2), the B method diagnosis is also performed for trips for which the A method diagnosis is not completed.

When the A method diagnosis and the B method diagnosis are separately executed and the leak is individually determined, the A method diagnosis is continuously established by two trips (1) or after two trips . The leak diagnosis result can be determined only when the B method diagnosis is continuously established during the stop period (3) . On the other hand, according to the leak diagnosis algorithm executed by the controller 10, leak diagnosis results can be obtained for all cases (1) to (3) above. Here, “A method diagnosis is established continuously” means that the detection of the presence or absence of a leak and the leak level when there is a leak by the A method diagnosis are completed twice in succession. Further, “the A method diagnosis is completed with one trip” means that the detection of the presence or absence of a leak and the level of a leak when there is a leak are completed by the A method diagnosis with one trip. “The other trip does not complete” means that the detection of the presence or absence of a leak and the detection of the leak level when there is a leak in the other trip have not been completed in the other trip.

  In addition, when the A method diagnosis and the B method diagnosis are separately executed and the leak is individually determined, the diagnosis result including the leak level can be obtained only in the case of (1) above. On the other hand, according to the algorithm of FIG. 2, a diagnostic result including a leak level can be obtained for (1) and (2). In other words, the probability of obtaining a diagnosis result including a leak level is increased fivefold under the above assumption regarding the diagnosis completion frequency.

  4A and 4B show a leak level determination routine executed by the controller 10 based on this idea.

  The controller 10 executes this routine at a leak diagnosis timing for each trip of the vehicle. Here, a section from the start of travel of the vehicle to the start of the next travel is referred to as a trip. The trip includes a stop period from when the vehicle stops traveling until the next traveling starts.

  In step S11, the controller 10 executes a leak diagnosis for the current trip. This routine is common to the A method diagnosis and the B method diagnosis. In step S11, when the current leak diagnosis timing corresponds to the A method diagnosis, the A method diagnosis is executed, and when the current leak diagnosis timing corresponds to the B method diagnosis, the B method diagnosis is executed. .

  In the next step S12, the controller 10 determines whether or not the leak diagnosis executed in step S11 is the A method diagnosis. If it is not the A method diagnosis, the controller 10 executes the processing after step S25. On the other hand, in the case of the A method diagnosis, the controller 10 determines whether a gross leak is detected in step S13.

  If a gross leak is detected, the controller 10 determines in step S14 whether a gross leak has been detected even in the previous trip. For this determination, the A method diagnosis result stored in the nonvolatile memory as described above is used. If the determination in step S14 is affirmative, it means that a gross leak has been detected continuously in two trips. Therefore, the controller 10 displays on the warning light that a gross leak exists in step S15, and then ends the routine.

  If the determination in step S14 is negative, the controller 10 determines in step S16 whether or not a leak has been detected in the B trip diagnosis of the previous trip based on the diagnosis result stored in the nonvolatile memory. In addition, the leak detected in the B method diagnosis is a leak of 0.02 inches or more.

  If the determination in step S16 is affirmative, the controller 10 displays on the warning light that there is a gross leak in step S15, and then ends the routine. On the other hand, if the determination in step S16 is negative, the controller 10 does nothing and ends the routine.

  If the determination in step S16 is affirmative, gross leak is not detected in the previous trip A method diagnosis, 0.02 inch or more is detected in the B method diagnosis, and gross leak is detected in the current trip A method diagnosis. Is detected. In the conventional diagnosis method, in this case, it is not determined that a gross leak exists. On the other hand, in this case, the leak diagnosis apparatus increases the chance of obtaining the final diagnosis result by considering the diagnosis result of the B method diagnosis even in such a case. In other words, even if no gross leak was detected in the previous trip A method diagnosis, a leak of 0.02 inches or more was detected in the B method diagnosis, so that the gross leak detected in the current A method diagnosis is It is determined that the data is reliable.

  If the gross leak is not detected in the current leak diagnosis in step S13, the controller 10 determines in step S17 whether a 0.04 inch leak is detected in the current A-system diagnosis. If a 0.04 inch leak is detected, the controller 10 determines in step S18 whether a 0.04 inch leak has been detected even during the previous trip. For this determination, the A method diagnosis result stored in the nonvolatile memory as described above is used.

  If the determination in step S18 is affirmative, it means that 0.04 inch leak has been detected continuously in two trips. Accordingly, the controller 10 displays on the warning light that a 0.04 inch leak exists in step S19, and then ends the routine. On the other hand, if the determination in step S20 is negative, the controller 10 does nothing and ends the routine.

  If the determination in step S18 is negative, the controller 10 determines in step S20 whether or not a leak has been detected in the B trip diagnosis of the previous trip based on the diagnosis result stored in the nonvolatile memory. As described above, the leak detected in the B method diagnosis is a leak of 0.02 inches or more.

  If the determination in step S20 is affirmative, a 0.04 inch leak is not detected in the previous trip A method diagnosis, but a 0.02 inch or more leak is detected in the B method diagnosis. In this case, a 0.04 inch leak is detected. In the conventional diagnostic method, in this case, it was not determined that a 0.04 inch leak exists. On the other hand, in this case, the leak diagnosis apparatus increases the chance of obtaining the final diagnosis result by considering the diagnosis result of the B method diagnosis. In other words, even if a 0.04 inch leak was not detected in the previous trip A method diagnosis, a 0.02 inch or more leak was detected in the B method diagnosis. The determined 0.04 inch leak is determined to be reliable as data.

  If no 0.04 inch leak has been detected in step S17, the controller 10 determines in step S21 whether a 0.02 inch leak has been detected in the current A method diagnosis. If a 0.02 inch leak is detected, the controller 10 determines in step S22 whether a 0.02 inch leak has been detected even in the previous trip. For this determination, the A method diagnosis result stored in the nonvolatile memory as described above is used.

  If the determination in step S22 is affirmative, it means that 0.02 inch leak has been detected continuously in two trips. Therefore, the controller 10 displays on the warning light that a 0.02 inch leak exists in step S23, and then ends the routine. On the other hand, if the determination in step S22 is negative, the controller 10 determines in step S24 whether or not a leak has been detected in the B trip diagnosis of the previous trip based on the diagnosis result stored in the nonvolatile memory. As described above, the leak detected in the B method diagnosis is a leak of 0.02 inches or more.

  If the determination in step S24 is affirmative, a 0.02 inch leak is not detected in the previous trip A method diagnosis, but a 0.02 inch or more leak is detected in the B method diagnosis. This is a case where a 0.02 inch leak is detected. In the conventional diagnosis method, in this case, it was not determined that a 0.02 inch leak exists. On the other hand, in this case, the leak diagnosis apparatus increases the chance of obtaining the final diagnosis result by considering the diagnosis result of the B method diagnosis. In other words, even if a 0.02 inch leak was not detected in the previous trip A method diagnosis, a 0.02 inch or more leak was detected in the B method diagnosis. The determined 0.02 inch leak is determined to be reliable as data.

  The above is the case where the A method diagnosis is performed in step S11. When the B system diagnosis is performed in step S11, the determination in step S12 is negative, and the controller 10 performs the processing from step S25 onward as described above.

  In step S25, the controller 10 determines whether or not a leak of 0.02 inches or more has been detected in the B-type diagnosis of the current trip.

  If a leak of 0.02 inches or more is detected, the controller 10 determines whether or not any leak has been detected in the previous trip A method diagnosis from the A method diagnosis result stored in the nonvolatile memory in step S26. To do.

  If the determination in step S26 is affirmative, the controller 10 determines in step S27 whether the gross leak is detected in the A trip diagnosis of the previous trip. If the gross leak is detected in the A trip diagnosis of the previous trip, the controller 10 displays a warning light on the presence of the gross leak in step S28, and then ends the routine.

  Here, a gross leak is detected in the A trip diagnosis of the previous trip, and if a leak of 0.02 inches or more is detected in the B trip diagnosis of the current trip, a gross leak is detected in the A trip diagnosis of the current trip. Even if it is not performed, it is determined that the gross leak detected in the A method diagnosis of the previous trip is reliable as data from the B method diagnosis result of the current trip.

On the other hand, if the determination in step S27 is negative, the controller 10 determines in step S29 whether the leak detected in the previous trip A method diagnosis is a 0.04 inch leak. If a 0.04 inch leak was detected in the A trip diagnosis of the previous trip, the controller 10 displays on the warning light that a 0.04 inch leak exists in step S30, and then ends the routine. .

  Here, when a 0.04 inch leak is detected in the A trip diagnosis of the previous trip and a leak of 0.02 inches or more is detected in the B trip diagnosis of the current trip, 0 is detected in the A trip diagnosis of the current trip. Even if a .04 inch leak is not detected, it is determined that the 0.04 inch leak detected by the A method diagnosis of the previous trip is reliable as data from the B method diagnosis result of the current trip.

  On the other hand, if the determination in step S29 is negative, step S26 is positive, indicating that a 0.02 inch leak has been detected. From the determination result of step S25, since a leak of 0.02 inches or more is detected in the current B method diagnosis, it is determined that the A method diagnosis result of the previous trip is supported by the B method diagnosis result of the current trip, In step S32, the controller 10 displays on the warning light that a 0.02 inch leak exists, and then ends the routine.

  On the other hand, if it is determined in step S26 that no leak was detected in the previous trip A method diagnosis, the controller 10 stores in step S31 whether or not a leak was detected in the previous trip B method diagnosis in the nonvolatile memory. Judgment is made based on the diagnosis result. If a leak is detected in the B trip diagnosis of the previous trip, the leak is detected in the B trip diagnosis for two consecutive trips together with the result of the B trip diagnosis of the current trip. In this case, the controller 10 displays on the warning light that a 0.02 inch leak exists in step S32, and then ends the routine.

  On the other hand, if it is determined in step S31 that no leak was detected in the B trip diagnosis of the previous trip, a leak was detected in the B trip diagnosis of the previous trip, but the A trip diagnosis of the previous trip and the B trip of the current trip are detected. It means that no leak was detected in any of the diagnoses. In this case, the controller 10 ends the routine without doing anything.

  Even if a leak of 0.02 inches or more is not detected by the current B method diagnosis in step S25, the controller 10 similarly does nothing and ends the routine.

  As described above, according to the leak diagnosis apparatus of the present invention, the leak level is determined by cross-referencing the result of the A method diagnosis and the result of the B method diagnosis that have been conventionally performed individually. Opportunities for obtaining diagnostic results can be greatly increased.

  Further, since the B method diagnosis is executed only when the A method diagnosis is not completed, it is possible to obtain a ridge with a low execution frequency of the B method while maintaining a high frequency of obtaining the diagnosis result. Therefore, it is possible to minimize the consumption of the battery power consumed by the execution of the B method diagnosis while the vehicle is stopped.

  In the above embodiment, step S1 in FIG. 2 constitutes means for executing the first leak diagnosis, and step S3 constitutes means for executing the second leak diagnosis. Steps S14, S18, and S22 in FIG. 4A constitute a first determination unit, and steps S16, S20, and S24 in FIG. 4A and steps S26, S27, S29, and S31 in FIG. 4B constitute a second determination unit. Further, step S2 in FIG. 2 constitutes prohibiting means.

  As mentioned above, although this invention has been demonstrated through the specific Example, this invention is not limited to a specific embodiment. Those skilled in the art can make various modifications or changes to the above-described embodiments within the technical scope of the claims.

  In each of the above embodiments, parameters necessary for control are detected using sensors, but the present invention does not depend on the parameter acquisition method, and any parameter that executes the claimed control using parameters. It can also be applied to a leak diagnosis apparatus.

1 is a schematic configuration diagram of an evaporated fuel purge system for an internal combustion engine equipped with a leak diagnosis apparatus according to an embodiment of the present invention. It is a flowchart explaining the basic algorithm of the leak diagnosis which a leak diagnostic apparatus performs. It is a timing chart explaining the implementation conditions of B system diagnosis. It is a flowchart explaining the leak diagnostic routine which a leak diagnostic apparatus performs. It is a flowchart explaining the leak diagnostic routine which a leak diagnostic apparatus performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Evaporative fuel barge passage 3 Vent line 4 Canister 4a Adsorbent 5 Vent cut valve 6 Purge passage 7 Purge valve 8 Pressure sensor 9 Temperature sensor 10 Controller 11 Atmospheric release passage 13 Outside air temperature sensor 21 Internal combustion engine 22 Intake pipe 23 Fuel injection valve 24 Combustion Chamber 25 Exhaust pipe 26 Catalyst 27 Throttle

Claims (6)

In a leak diagnosis apparatus for an evaporated fuel barge passage of an internal combustion engine for a vehicle,
Means for executing a first leak diagnosis for determining the presence or absence of a leak including a leak level for each travel of the vehicle;
Means for executing a second leak diagnosis for determining only the presence or absence of a leak of a specific level or more for each stop of the vehicle;
A first determination unit that determines a leak level according to a first leak diagnosis result detected twice in succession when a leak of the same level is detected twice in succession in the first leak diagnosis;
When a leak level is detected in the first leak diagnosis and a leak of a specific level or more is detected in the second leak diagnosis immediately before or after that, the leak is detected based on the leak level detected in the first leak diagnosis. A second determining means for determining the level;
An apparatus for diagnosing a leak in an evaporated fuel barge passage of an internal combustion engine for a vehicle, comprising: 2. The apparatus according to claim 1, further comprising means for prohibiting a second leak diagnosis performed immediately after the first leak diagnosis when a leak level is determined by execution of the first leak diagnosis. Apparatus for diagnosing evaporative fuel barge passage of an internal combustion engine for vehicles. When the second determination means determines that there is a leak of a specific level or more in the second leak diagnosis immediately before or immediately after the first leak diagnosis in which the leak is detected , the second determination means leak diagnostic apparatus for evaporative fuel barge passage of a vehicle internal combustion engine according to claim 1 or 2, characterized in that to determine the leak level detected in the first leak diagnosis as leak level. The leak diagnosis apparatus for an evaporative fuel barge passage of an internal combustion engine for a vehicle according to any one of claims 1 to 3, wherein the leak level is 0.02 inch leak, 0.04 inch leak, and gross leak. . The leak diagnosis apparatus for an evaporative fuel barge passage of an internal combustion engine for a vehicle according to any one of claims 1 to 4, wherein the specific level is 0.02 inch leak. In a method for diagnosing a leak in an evaporated fuel barge passage of an internal combustion engine for a vehicle,
Performing a first leak diagnosis for determining the presence or absence of a leak including a leak level for each travel of the vehicle;
Performing a second leak diagnosis for determining whether or not there is a leak of a specific level or more for each stop of the vehicle;
When leaks of the same level are detected twice in succession in the first leak diagnosis, the leak level is determined according to the first leak diagnosis result detected twice in succession,
When a leak level is detected in the first leak diagnosis and a leak of a specific level or more is detected in the second leak diagnosis immediately before or after that, the leak is detected based on the leak level detected in the first leak diagnosis. Confirm the level,
A method for diagnosing a leak in an evaporated fuel barge passage of an internal combustion engine for a vehicle.

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