JP2004300997A - Leakage diagnostic device for evaporated gas purging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent erroneous diagnosis of leakage by detecting the presence of abnormality of a leak check module provided with a reference pressure detecting section, a passage-switching valve and a pump. <P>SOLUTION: A reference pressure detecting process for detecting a reference pressure by switching a pressure introducing path of a vacuum pump 23 by the passage-switching valve 19 and introducing a negative pressure into the reference pressure detecting section 37, and an in-evaporation system pressure detecting process for detecting a pressure in a evaporation system by introducing the negative pressure into the evaporation system, are performed and the pressure in the evaporation system is compared with the reference pressure, so that the leakage in the evaporation system is diagnosed. In this case, the presence of the leak check module 17 (the reference pressure detecting section 37, the passage-switching valve 19, the vacuum pump 23 and the like) is diagnosed by detecting whether the reference pressure detected by the reference pressure detecting process is within a normal range or not, and the presence of abnormality of the vacuum pump 23 is diagnosed by comparing an arrival time required for the pressure in the reference pressure detecting section 37 to be lowered to a prescribed value with an abnormality judging value while detecting the reference pressure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a leak diagnosis device for an evaporative gas purge system that performs a leak diagnosis of an evaporative gas purge system that purges (discharges) evaporative gas (fuel evaporative gas) generated by evaporating fuel in a fuel tank into an intake system of an internal combustion engine. It is.
[0002]
[Prior art]
Conventionally, in an evaporative gas purge system, in order to prevent evaporative gas generated from the fuel tank from leaking into the atmosphere, the evaporative gas generated from the fuel tank is adsorbed in the canister, and the canister and the intake air of the internal combustion engine are sucked. By opening a purge control valve provided in a purge passage communicating with the system, the negative pressure of the intake system is used to purge the evaporative gas adsorbed in the canister to the intake system. In order to prevent a state in which the evaporative gas leaks from the evaporative gas purge system into the atmosphere for a long time, it is necessary to detect the evaporative gas leak at an early stage.
[0003]
Therefore, for example, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 5-125997), the purge control valve is opened during operation of the internal combustion engine to introduce a negative pressure from the intake system into the fuel tank. Thereafter, while the purge control valve is closed and the evaporative system from the purge control valve to the fuel tank is closed, the amount of change in the pressure in the evaporative system (for example, the pressure in the fuel tank) is measured, and the negative pressure is introduced. In some cases, the presence / absence of a leak (leakage) in an evaporative system is determined by comparing a pressure change amount at the time with a leak determination value (for example, a pressure change amount when introducing atmospheric pressure).
However, the above-described conventional leak diagnosis has a disadvantage that it is not possible to accurately determine a minute leak or a leak degree (the size of a leak hole).
[0004]
Therefore, for example, as described in Patent Document 2 (Japanese Patent Laid-Open No. 2002-4959), an electric negative pressure pump and a reference hole (a hole having a predetermined diameter corresponding to a minute leak hole) are formed. A pressure detecting section, a path switching valve for switching between a path for introducing a negative pressure into the reference pressure detecting section by the negative pressure pump and a path for introducing the negative pressure into the evaporative system by the negative pressure pump are provided, and the reference pressure is supplied by the negative pressure pump. By introducing a negative pressure into the pressure detector and detecting the pressure in the reference pressure detector, the pressure regulated by the reference hole (reference pressure) is detected. By switching, the negative pressure is introduced into the evaporative system by the negative pressure pump under the same conditions as when detecting the reference pressure, the pressure in the evaporative system is detected, and the reference pressure and the pressure in the evaporative system are compared. Micro leak and leak degree can be determined There is a thing was.
[0005]
[Patent Document 1]
JP-A-5-125997 (page 2, etc.)
[Patent Document 2]
JP-A-2002-4959 (page 2, etc.)
[0006]
[Problems to be solved by the invention]
By the way, for example, when the reference hole of the reference pressure detecting unit is clogged with foreign matter such as a condensed evaporative component or dust, or when an abnormality such as an operation failure of the passage switching valve or an operation failure of the pump occurs, the reference pressure detection processing or the evaporative system. The pressure detection processing cannot be performed normally, and the detected values of the reference pressure and the pressure in the evaporation system become abnormal values. However, in the system of Patent Document 2, even if some abnormality occurs in the reference pressure detection unit, the passage switching valve, the pump, and the like, and the detection values of the reference pressure and the evaporative system pressure are abnormal values, Since there is no means for detecting the abnormality, the leak diagnosis is performed using the abnormal reference pressure or the evaporative system internal pressure, and there is a possibility that the leak diagnosis is erroneously determined.
[0007]
The present invention has been made in view of such circumstances, and therefore, its purpose is to perform a leak diagnosis using a pressure introduction detection device including a reference pressure detection unit, a passage switching valve, a pump, and the like. It is an object of the present invention to provide a leak diagnostic device for an evaporative gas purge system that can detect an abnormality of a pressure introduction detection device and prevent erroneous determination of a leak due to an abnormality of the pressure introduction detection device.
[0008]
[Means for Solving the Problems]
To achieve the above object, a leak diagnostic apparatus for an evaporative gas purge system according to claim 1 of the present invention determines whether or not a reference pressure detected by a reference pressure detection process is within a predetermined normal range, and performs pressure introduction. This is to determine the presence or absence of an abnormality in the detection device. If the pressure introduction detection device (the reference pressure detection unit, the passage switching valve, the pump, etc.) is normal, the fluctuation amount (variation width) of the reference pressure is relatively small within a relatively small fluctuation range due to a change in atmospheric pressure, temperature, etc. (Variation width). Therefore, if it is determined whether or not the reference pressure is within a predetermined normal range (a normal variation range set in consideration of a variation range due to a change in atmospheric pressure, temperature, and the like), the abnormality of the pressure introduction detection device is determined. Can be determined. This makes it possible to stop the leak diagnosis or to invalidate the leak diagnosis result when it is determined that there is an abnormality in the pressure introduction detection device. And erroneous determination of the degree of leak can be prevented beforehand.
[0009]
In addition, the pressure change speed in the reference pressure detection unit during the reference pressure detection process or information correlated therewith (hereinafter referred to as “pressure change speed information”) is detected, and the pressure change speed information is detected. May be compared with a predetermined abnormality determination value to determine whether there is an abnormality in the pump. If any abnormality occurs in the pump and the pump flow rate decreases, the rate of change of the pressure in the reference pressure detection unit during the reference pressure detection process becomes slow. Therefore, the information on the pressure change rate is compared with a predetermined abnormality determination value. Then, it is possible to determine whether there is an abnormality in the pump.
[0010]
Further, when it is determined that there is an abnormality in the pressure introduction detection device, a cleaning process for switching the passage switching valve is performed, and then abnormality diagnosis of the pressure introduction detection device is performed again. Is also good. For example, when the passage switching valve is caught by foreign matter such as dust and an operation failure of the passage switching valve occurs, and it is determined that the pressure introduction detection device is abnormal, the passage switching valve is switched. By executing the cleaning process, the passage switching valve may remove the stuck foreign matter and return to a normal state. Further, after performing the cleaning process, the abnormality diagnosis of the pressure introduction detection device is performed again, whereby it is possible to confirm whether the pressure introduction detection device (the passage switching valve) has returned to the normal state.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the configuration of the evaporation gas purge system will be described with reference to FIG. A canister 13 is connected to the fuel tank 11 via an evaporation passage 12. The canister 13 contains an adsorbent (not shown) such as activated carbon for adsorbing evaporative gas (fuel evaporative gas).
[0012]
On the other hand, between the canister 13 and the engine intake system, a purge passage 14 for purging (releasing) the evaporative gas adsorbed by the adsorbent in the canister 13 to the engine intake system is provided. A purge control valve 15 for controlling the purge flow rate is provided on the way. The purge control valve 15 is constituted by a normally-closed solenoid valve, and controls the purge flow rate of evaporative gas from the canister 13 to the engine intake system by duty control of energization.
[0013]
A leak check module 17 (pressure introduction detection device) is attached to the atmosphere communication passage 16 of the canister 13 in order to perform a leak diagnosis of the evaporation system from the fuel tank 11 to the purge control valve 15. As shown in FIG. 2, in the leak check module 17, an atmosphere communication path 20 and a negative pressure introduction path 21 are connected to a canister communication path 18 connected to the canister 13 via a path switching valve 19. The atmosphere communication path 20 is provided so as to directly communicate with the atmosphere side, and the negative pressure introduction path 21 is connected in the middle of the atmosphere communication path 20 via a check valve 22 and an electric negative pressure pump 23. . During operation of the negative pressure pump 23, the check valve 22 is opened to discharge gas from the negative pressure introduction passage 21 to the atmosphere communication passage 20. When the negative pressure pump 23 is stopped, the check valve 22 is closed and air communication is performed. The backflow of the atmosphere from the passage 20 to the negative pressure introduction passage 21 is prevented.
[0014]
The passage switching valve 19 performs a switching operation between an atmosphere opening position B connecting the canister communication passage 18 and the atmosphere communication passage 20 and a negative pressure introduction position A connecting the canister communication passage 18 and the negative pressure introduction passage 21. It consists of a possible solenoid valve.
[0015]
A bypass passage 24 that bypasses the passage switching valve 19 is connected between the canister communication passage 18 and the negative pressure introduction passage 21, and a reference orifice 25 (reference hole) is provided in the middle of the bypass passage 24. ing. The reference orifice 25 is formed so that the inside diameter of the passage is narrowed significantly from the inside diameter of the passage at the other part of the bypass passage 24 and becomes the reference leak hole diameter (for example, 0.5 mm in diameter). The reference orifice 25 and a passage 24a of the bypass passage 24 which is connected from the reference orifice 25 to the negative pressure introducing passage 21 constitute a reference pressure detecting unit 37, and the reference pressure detecting unit 37 is provided with a pressure sensor 26. I have.
[0016]
When the passage switching valve 19 is switched to the negative pressure introducing position A when the purge control valve 15 is closed, the evaporative system is closed and the peripheral portion of the pressure sensor 26 of the reference pressure detecting unit 37 is connected to the negative pressure introducing passage 21. Since the pressure sensor 26 communicates with the evaporative system via the canister communication passage 18, the pressure in the evaporative system can be detected by detecting the pressure in the reference pressure detector 37 by the pressure sensor 26.
[0017]
When the negative pressure pump 23 is driven in a state where the passage switching valve 19 is switched to the negative pressure introducing position A and the evaporative system is closed, the gas in the evaporative system is discharged to the atmosphere through the canister 13. Then, a negative pressure is introduced into the evaporation system.
[0018]
On the other hand, when the passage switching valve 19 is switched to the atmosphere opening position B when the purge control valve 15 is closed, the inside of the bypass passage 24 (the inside of the reference pressure detecting unit 37) is opened to the atmosphere via the atmosphere communication passage 20. Therefore, the atmospheric pressure can be detected by detecting the pressure in the reference pressure detector 37 by the pressure sensor 26.
[0019]
When the negative pressure pump 23 is driven in a state where the passage switching valve 19 is switched to the atmosphere opening position B and the inside of the evaporation system is opened to the atmosphere through the atmosphere communication passage 20, the reference orifice 25 exists. The inside of the reference pressure detector 37 becomes negative pressure. At this time, by detecting the pressure in the reference pressure detecting unit 37 by the pressure sensor 26, the reference pressure corresponding to the reference leak hole diameter of the reference orifice 25 can be detected.
[0020]
Further, as shown in FIG. 1, a fuel level sensor 27 for detecting the remaining fuel amount is provided in the fuel tank 11. In addition, various sensors such as a crank angle sensor 28 that outputs a crank angle signal for each predetermined crank angle, an intake pipe pressure sensor 29 that detects an intake pipe pressure, and a vehicle speed sensor 30 that detects a vehicle speed are provided.
[0021]
Outputs of these various sensors are input to a control circuit (hereinafter referred to as “ECU”) 31. A power supply terminal of the ECU 31 is supplied with a power supply voltage from a vehicle-mounted battery (not shown) via a main relay 32. In addition, a power supply voltage is also supplied to the purge control valve 15, the passage switching valve 19, the negative pressure pump 23, the pressure sensor 26, the fuel level sensor 27, and the like via the main relay 32. A relay drive coil 32b for driving a relay contact 32a of the main relay 32 is connected to a main relay control terminal of the ECU 31. When the relay drive coil 32b is energized, the relay contact 32a is turned on, and the ECU 31 and the like are turned on. Is supplied with a power supply voltage. Then, by turning off the power supply to the relay drive coil 32b, the relay contact 32a is turned off, and the power supply to the ECU 31 and the like is turned off.
[0022]
An ON / OFF signal of an ignition switch (hereinafter, referred to as an “IG switch”) 33 is input to a key SW terminal of the ECU 31. When the IG switch 33 is turned on, the main relay 32 is turned on and power supply to the ECU 31 and the like is started. When the IG switch 33 is turned off, the main relay 32 is turned off and the power supply to the ECU 31 and the like is turned off. .
[0023]
Further, the ECU 31 has a backup power supply 34 and a soak timer 35 that operates to measure time using the backup power supply 34 as a power supply. The soak timer 35 starts a timing operation after the engine stops (after the IG switch 33 is turned off) and measures the elapsed time after the engine stops. As described above, when the IG switch 33 is turned off, the main relay 32 is turned off and the power supply to the ECU 31 and the like is turned off. However, in order to perform a leak diagnosis while the engine is stopped, the measurement time of the soak timer 35 (engine When the elapsed time after the stop reaches a predetermined time (for example, 3 to 5 hours), the drive circuit of the main relay control terminal of the ECU 31 is operated by using the backup power supply 34 of the ECU 31 as a power source, and the main relay 32 is turned on. The power supply voltage is supplied to the purge control valve 15, the passage switching valve 19, the negative pressure pump 23, the pressure sensor 26, the fuel level sensor 27, and the like.
[0024]
The ECU 31 is mainly configured by a microcomputer, and performs fuel injection control, ignition control, and purge control by executing a fuel injection control program, an ignition control program, and a purge control program stored in its ROM (storage medium). .
[0025]
Further, the ECU 31 executes a leak diagnosis program shown in FIGS. 3 and 4 described later to control the leak check module 17 to detect the reference pressure and the pressure in the evaporative system. Diagnose for leaks.
[0026]
Here, the leak diagnosis of the evaporation system performed in the present embodiment will be described. As shown in FIG. 5, the reference pressure detection processing is started at a time point t1 when a predetermined time (for example, 3 to 5 hours) has elapsed since the engine operation was stopped (the IG switch 33 was turned off). In this reference pressure detection process, the negative pressure pump 23 is turned on while the purge control valve 15 is maintained in the closed state and the passage switching valve 19 is maintained at the atmosphere open position B, and the negative pressure It is assumed that the negative pressure in the reference pressure detector 37 has stabilized near the reference pressure corresponding to the reference orifice 25 at a time t2 when a predetermined time T0 has elapsed from the start of the introduction of the negative pressure into the reference pressure detector 37. After the determination, the pressure in the reference pressure detecting section 37 detected by the pressure sensor 26 is stored in the memory of the ECU 31 as the reference pressure P0.
[0027]
After detecting the reference pressure P0, the evaporative system pressure detection process is started. In the evaporative system pressure detection process, the passage switching valve 19 is switched to the negative pressure introducing position A while the negative pressure pump 23 is kept in the ON state, and the negative pressure pump 23 introduces a negative pressure into the evaporative system. At a time t3 when a predetermined time Tevp has elapsed from the start of introduction of the negative pressure into the evaporative system, the pressure Pevp in the evaporative system is detected by the pressure sensor 26 and stored in the memory of the ECU 31.
[0028]
Thereafter, the evaporative system internal pressure Pevp is compared with a leak determination value (for example, a reference pressure P0 or a value set to a pressure slightly lower than the reference pressure), and if the evaporative system internal pressure Pevp is equal to or less than the leak determination value, It is determined that there is no leak. On the other hand, if the evaporation system pressure Pevp is higher than the leak determination value, it is determined that there is a leak. At this time, if the evaporative system internal pressure Pevp converges to the vicinity of the reference pressure P0, it is determined that the evaporative system internal pressure Pevp is equal to the reference orifice 25 diameter (for example, 0.5 mm). If it is higher than P0, it is determined that the leak hole is larger than the reference leak hole diameter of the reference orifice 25.
[0029]
By the way, for example, the reference orifice 25 of the reference pressure detecting unit 37 is clogged with foreign matter such as a condensed evaporative component or dust, the operation failure of the passage switching valve 19 or the operation failure of the negative pressure pump 23, etc. When the abnormality occurs, the reference pressure detection process and the evaporative system pressure detection process cannot be performed properly, and the reference pressure and the evaporative system pressure are erroneously detected. If leak diagnosis is performed using the erroneously detected reference pressure or the evaporative system pressure, there is a problem that the presence or absence of a leak is erroneously determined or the degree of leak (the size of a leak hole) is erroneously determined.
[0030]
Therefore, when executing the leak diagnosis program shown in FIGS. 3 and 4, the ECU 31 performs the leak check module 17 (the reference pressure detecting unit 37, the passage switching valve 19, It is determined whether there is an abnormality in the negative pressure pump 23).
[0031]
In the first abnormality determination method, as shown in FIG. 6, whether the reference pressure P0 detected by the reference pressure detection processing is within a predetermined normal range (lower threshold TP2 <reference pressure P0 <upper threshold TP1). Is determined. This normal range is a normal variation range set in consideration of a variation range of the reference pressure due to a change in atmospheric pressure, temperature, and the like. If the reference pressure P0 is not within the normal range, there is some abnormality in the leak check module 17 (for example, clogging of the reference orifice 25 of the reference pressure detection unit 37, malfunction of the passage switching valve 19, malfunction of the negative pressure pump 23). Then, the negative pressure pump 23 is turned off to prohibit (cancel) the leak diagnosis.
[0032]
As shown in FIG. 7, the second abnormality determination method uses, as a substitute for the rate of change of the pressure in the reference pressure detection unit 37 during the reference pressure detection processing, the start of introduction of the negative pressure into the reference pressure detection unit 37. The arrival time T1 required for the pressure in the reference pressure detecting unit 37 to decrease to a predetermined value (for example, the upper limit threshold value TP1 of the normal range of the reference pressure or a pressure slightly higher than the upper threshold value TP1) is obtained. Is compared with the abnormality determination value. When the arrival time T1 is longer than the abnormality determination value (that is, when the pressure change speed is slow), it is determined that the negative pressure pump 23 is abnormal (for example, the flow rate of the negative pressure pump 23 is reduced), and the negative pressure pump 23 is turned off. To prohibit (cancel) leak diagnosis.
[0033]
Hereinafter, the processing contents of the leak diagnosis program shown in FIGS. 3 and 4 executed by the ECU 31 will be described.
The leak diagnosis program shown in FIGS. 3 and 4 is executed at predetermined time intervals (for example, every 20 msec) after the main relay 32 is turned on by the soak timer 35 after the IG switch 33 is turned off, for example. And plays a role as abnormality determination means. When the program is started, first, at step 101, it is determined whether or not the IG switch 33 is turned off and the leak diagnosis during engine stop has not been performed. If it is determined that the IG switch 33 is ON or that the leak diagnosis while the engine is stopped has been performed, the program is immediately terminated.
[0034]
On the other hand, if it is determined that the IG switch 33 is turned off and the leak diagnosis during engine stop has not been performed, the process proceeds to step 102, where the purge control valve 15 is kept closed and the passage switching valve 19 is turned off. The negative pressure pump 23 is maintained in the OFF state while maintaining the air release position B.
[0035]
Thereafter, the routine proceeds to step 103, where it is determined whether or not the leak diagnosis execution condition is satisfied. Here, the leak diagnosis execution condition is, for example, that all of the following conditions (1) to (3) are satisfied.
(1) The IG switch 33 is turned off (the engine is stopped)
(2) A predetermined time (for example, 3 to 5 hours) has elapsed since the IG switch 33 was turned off. (3) The remaining amount of fuel in the fuel tank 11 is within a predetermined range.
If all of the above conditions (1) to (3) are satisfied, the leak diagnosis execution condition is satisfied. However, if there is a condition that does not satisfy any one of the above conditions (1) to (3), the leak diagnosis is performed. The execution condition is not satisfied. If it is determined that the leak diagnosis execution condition is not satisfied, the program ends without executing the processes related to the leak diagnosis after step 104.
[0037]
On the other hand, when it is determined in step 103 that the leak diagnosis execution condition is satisfied, the processes related to the leak diagnosis from step 104 are executed as follows. First, at step 104, the negative pressure pump 23 is turned on to introduce a negative pressure into the reference pressure detecting section 37. Thereafter, the process proceeds to step 105, and when the pressure in the reference pressure detecting unit 37 detected by the pressure sensor 26 decreases to the upper threshold TP1 of the normal range of the reference pressure, the negative pressure to the reference pressure detecting unit 37 is reduced. The arrival time T1 required for the pressure in the reference pressure detecting section 37 to decrease to the upper threshold TP1 from the start of the introduction is stored in the memory of the ECU 31.
[0038]
Thereafter, the process proceeds to step 106, where it is determined whether or not a predetermined time T0 has elapsed from the start of the introduction of the negative pressure into the reference pressure detecting unit 37. If the predetermined time T0 has not elapsed, the process returns to step 103.
[0039]
Thereafter, at step 106, when it is determined that the predetermined time T0 has elapsed from the start of the introduction of the negative pressure into the reference pressure detection unit 37, the negative pressure in the reference pressure detection unit 37 is reduced to the reference leak hole diameter of the reference orifice 25. It is determined that the pressure is stable near the corresponding reference pressure, and the routine proceeds to step 107, where the pressure in the reference pressure detector 37 detected by the pressure sensor 26 is stored in the memory of the ECU 31 as the reference pressure P0.
[0040]
Thereafter, the process proceeds to step 108, where the arrival time T1 required for the pressure in the reference pressure detection unit 37 to decrease to the upper threshold TP1 from the start of the introduction of the negative pressure into the reference pressure detection unit 37 is larger than the abnormality determination value. Determine if it is long. As a result, when it is determined that the arrival time T1 is longer than the abnormality determination value (that is, the pressure change speed is slow), the process proceeds to step 109, and there is an abnormality in the negative pressure pump 23 (for example, the flow rate of the negative pressure pump 23 is insufficient). ), The warning lamp 36 provided on the instrument panel of the driver's seat is turned on, or a warning is displayed on a warning display section (not shown) of the instrument panel to warn the driver, The abnormality information (the abnormality code and the like) is stored in a backup RAM (not shown) of the ECU 31.
[0041]
On the other hand, if it is determined in step 108 that the arrival time T1 is less than or equal to the abnormality determination value, the process proceeds to step 110, where the reference pressure P0 is within the normal range (lower threshold TP2 <reference pressure P0 <upper threshold. TP1) is determined. As a result, if it is determined that the reference pressure P0 is not within the normal range, the routine proceeds to step 111, where there is some abnormality in the leak check module 17 (for example, clogging of the reference orifice 25 of the reference pressure detection unit 37, passage switching). It is determined that the valve 19 is malfunctioning or the negative pressure pump 23 malfunctions, and the warning lamp 36 provided on the instrument panel in the driver's seat is turned on, or a warning indicator (not shown) on the instrument panel. ) Is displayed to warn the driver, and the abnormality information (abnormality code and the like) is stored in the backup RAM of the ECU 31.
[0042]
After it is determined in step 109 or 111 that there is an abnormality, the process proceeds to step 112, where the negative pressure pump 23 is turned off, and the program ends. As a result, the processing after step 113 in FIG. 4 described later is not executed, and the leak diagnosis is prohibited (stopped).
[0043]
On the other hand, if it is determined in step 108 that the arrival time T1 is equal to or less than the abnormality determination value, and if it is determined in step 110 that the reference pressure P0 is within the normal range, a leak check is performed. It is determined that there is no abnormality (normal) in the module 17 (the reference pressure detecting unit 37, the passage switching valve 19, the negative pressure pump 23, etc.), and the processing after step 113 in FIG. And do it.
[0044]
First, in step 113, the path switching valve 19 is switched to the negative pressure introduction position A while the negative pressure pump 23 is maintained in the ON state, and a negative pressure is introduced into the evaporation system by the negative pressure pump 23. Thereafter, the routine proceeds to step 114, where it is determined whether or not a predetermined time Tevp (for example, 10 minutes) has elapsed from the start of introduction of the negative pressure into the evaporative system. When the predetermined time Tevp has elapsed, the routine proceeds to step 115, It is determined whether or not the evaporation system pressure Pevp detected by the pressure sensor 26 is lower than a leak determination value (for example, a reference pressure P0 or a value set to a pressure slightly lower than the reference pressure P0).
As a result, when it is determined that the evaporative system internal pressure Pevp is equal to or smaller than the leak determination value, the routine proceeds to step 117, where it is determined that the evaporative system is normal (no leak).
[0045]
On the other hand, if it is determined in step 116 that the evaporative system internal pressure Pevp is higher than the leak determination value, the process proceeds to step 118, where it is determined that the evaporative system is abnormal (leakage is present), and the driver's seat is installed. The warning lamp 36 provided on the instrument panel is turned on, or a warning is displayed on a warning display section (not shown) of the instrument panel to warn the driver, and the abnormality information (abnormal code, etc.) is transmitted to the ECU 31. In the backup RAM.
[0046]
Thereafter, in step 119, a leak diagnosis end process is executed, the passage switching valve 19 is switched to the atmosphere opening position B, the negative pressure pump 23 is turned off, and the program ends.
[0047]
In this program, if it is determined that there is an abnormality in the leak check module 17 (the reference pressure detector 37, the passage switching valve 19, the negative pressure pump 23, etc.), the leak diagnosis is stopped. May be made invalid.
[0048]
In the present embodiment described above, when performing a leak diagnosis, it is determined whether or not the leak check module 17 has an abnormality by determining whether or not the reference pressure P0 detected by the reference pressure detection processing is within a normal range. Therefore, it is possible to detect an abnormality of the leak check module 17 (for example, clogging of the reference orifice 25 of the reference pressure detection unit 37, malfunction of the passage switching valve 19, malfunction of the negative pressure pump 23). In addition, as the pressure change speed information during the reference pressure detection processing, an arrival time T1 required for the pressure in the reference pressure detection unit 37 to decrease to a predetermined value (upper threshold TP1) is obtained. Since the value is compared with the value to determine whether there is an abnormality in the negative pressure pump 23, an abnormality in the negative pressure pump 23 (for example, a decrease in the flow rate of the negative pressure pump 23) can be detected.
[0049]
Thereby, when it is determined that there is an abnormality in the leak check module 17 (the reference pressure detecting unit 37, the passage switching valve 19, the negative pressure pump 23, etc.), the leak diagnosis is stopped, or the current leak diagnosis is performed. It is possible to invalidate the result, it is possible to prevent the presence or absence of a leak due to the abnormality of the leak check module 17 and to erroneously determine the degree of the leak, thereby improving the reliability of the leak diagnosis.
[0050]
When it is determined that there is an abnormality in the leak check module 17, a cleaning process of switching the passage switching valve 19 once or a plurality of times is executed, and thereafter, an abnormality diagnosis of the leak check module 17 is executed again. Is also good. For example, when the passage switching valve 19 is caught by foreign matter such as dust and an operation failure of the passage switching valve 19 occurs, and it is determined that the leak check module 17 is abnormal, the passage switching valve 19 is By performing the cleaning process for performing the switching operation, the passage switching valve 19 may remove the stuck foreign matter and return to the normal state. Further, after performing the cleaning process, the abnormality check of the leak check module 17 is performed again, so that it is possible to confirm whether the leak check module 17 (the passage switching valve 19) has returned to a normal state.
[0051]
In the above-described embodiment, the arrival time T1 required for the pressure in the reference pressure detection unit 37 to decrease to a predetermined value is used as the pressure change speed information during the reference pressure detection process, but is not limited thereto. For example, the amount of pressure change from the start of the introduction of the negative pressure into the reference pressure detection unit 37 to the elapse of a predetermined time may be used as the pressure change speed information. The pressure change rate may be obtained by division.
[0052]
Further, in the above embodiment, both the abnormality determination for determining whether the reference pressure P0 is within the normal range and the abnormality determination for comparing the pressure change speed information with the abnormality determination value are executed. However, only one of them may be executed.
[0053]
Further, in the above-described embodiment, abnormality diagnosis of the leak check module 17 (the reference pressure detection unit 37, the passage switching valve 19, the negative pressure pump 23, and the like) is performed using the reference pressure detection process when performing the leak diagnosis. However, the abnormality check of the leak check module 17 may be performed by executing the reference pressure detection process at a different time from the reference pressure detection process when performing the leak diagnosis.
[0054]
Further, in the above embodiment, the negative pressure pump 23 is used for performing the leak diagnosis. However, a positive pressure pump for introducing a positive pressure into the evaporation system may be used.
Further, in the above embodiment, the present invention is applied to a system for performing a leak diagnosis while the engine is stopped, but the present invention may be applied to a system for performing a leak diagnosis while the engine is operating.
[0055]
In addition, the present invention may appropriately change the configuration of the leak diagnosis system such as the evaporative gas purge system and the leak check module 17, and may appropriately change the specific method of determining the leak diagnosis. The present invention can be applied to any system that performs a leak diagnosis using a pressure introduction detection device including a passage switching valve, a pump, and the like.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an evaporative gas purge system according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of a leak check module. FIG. 3 is a flowchart (1) showing a flow of processing of a leak diagnosis program.
FIG. 4 is a flowchart showing a flow of processing of a leak diagnosis program (part 2);
FIG. 5 is a time chart showing an example of execution of a leak diagnosis. FIG. 6 is a time chart for explaining a first abnormality judgment method. FIG. 7 is a time chart for explaining a second abnormality judgment method. Description】
DESCRIPTION OF SYMBOLS 11 ... fuel tank, 12 ... evaporation passage, 13 ... canister, 14 ... purge passage, 15 ... purge control valve, 17 ... leak check module (pressure introduction detection apparatus), 18 ... canister communication passage, 19 ... passage switching valve, 20 ... atmosphere communication path, 21 ... negative pressure introduction path, 22 ... check valve, 23 ... negative pressure pump, 24 ... bypass path, 25 ... reference orifice (reference hole), 26 ... pressure sensor, 31 ... ECU (leak diagnosis means, Abnormality determining means), 32: main relay, 33: IG switch, 35: soak timer, 37: reference pressure detector.

Claims (4)

Applied to an evaporative gas purge system for purging evaporative gas generated by evaporating fuel in a fuel tank into an intake system of an internal combustion engine,
A pump for introducing a predetermined pressure into an evaporative system including the fuel tank, a reference pressure detecting unit having a reference hole with a predetermined hole diameter formed therein, and the pump introducing a predetermined pressure into the reference pressure detecting unit. A pressure introduction detection device having a path and a path switching valve for switching a path for introducing a predetermined pressure into the evaporation system by the pump,
A reference pressure detection for switching a pressure introduction path of the pump by the passage switching valve to introduce a predetermined pressure into the reference pressure detection unit and detect a pressure regulated by the reference hole (hereinafter, referred to as a “reference pressure”). Process, a predetermined pressure is introduced into the evaporative system, an evaporative system pressure detecting process for detecting a pressure in the evaporative system is performed, and the reference pressure and the pressure in the evaporative system are compared. In a leak diagnostic apparatus for an evaporative gas purge system comprising a leak diagnostic means for performing a leak diagnostic of the evaporative system,
An abnormality determination unit that determines whether the reference pressure detected by the reference pressure detection process is within a predetermined normal range and determines whether or not the pressure introduction detection device is abnormal is provided. Leak diagnostic device for evaporative gas purge system. The abnormality determination unit detects a pressure change speed in the reference pressure detection unit during the reference pressure detection process or information correlated therewith (hereinafter, referred to as “pressure change speed information”), and compares the pressure change speed information with a predetermined value. 2. The leak diagnosis apparatus for an evaporative gas purge system according to claim 1, wherein the presence or absence of an abnormality in the pump is determined by comparing the abnormality with a determination value. When the abnormality determination unit determines that there is an abnormality in the pressure introduction detection device, after performing a cleaning process of switching the passage switching valve, the abnormality determination unit performs the abnormality diagnosis of the pressure introduction detection device again. The leak diagnostic device for an evaporative gas purge system according to claim 1 or 2. Applied to an evaporative gas purge system for purging evaporative gas generated by evaporating fuel in a fuel tank into an intake system of an internal combustion engine,
A pump for introducing a predetermined pressure into an evaporative system including the fuel tank, a reference pressure detecting unit having a reference hole with a predetermined hole diameter formed therein, and the pump introducing a predetermined pressure into the reference pressure detecting unit. A pressure introduction detection device having a path and a path switching valve for switching a path for introducing a predetermined pressure into the evaporation system by the pump,
A reference pressure detection for switching a pressure introduction path of the pump by the passage switching valve to introduce a predetermined pressure into the reference pressure detection unit and detect a pressure regulated by the reference hole (hereinafter, referred to as a “reference pressure”). Process, a predetermined pressure is introduced into the evaporative system, an evaporative system pressure detecting process for detecting a pressure in the evaporative system is performed, and the reference pressure and the pressure in the evaporative system are compared. In a leak diagnostic apparatus for an evaporative gas purge system comprising a leak diagnostic means for performing a leak diagnostic of the evaporative system,
A pressure change speed in the reference pressure detection unit during the reference pressure detection process or information correlated therewith (hereinafter referred to as “pressure change speed information”) is detected, and the pressure change speed information is compared with a predetermined abnormality determination value. And an abnormality determining means for determining whether the pump is abnormal.

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