JP2001248503A - Abnormality diagnostic device for valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality diagnostic device for a valve capable of making a failure diagnosis relatively frequently without requiring the satisfaction of strict preconditions for starting the diagnostic process of the valve. SOLUTION: A valve closing instruction is issued to the valve 80a provided on a passage 80 connecting a fuel tank 30 and a canister 40. The fuel tank 30 is made an isolated space, and negative pressure is applied to the canister 40 via a purge passage 71. The internal pressure of the canister is estimated based on a gas purge flow, and the internal pressure of the fuel tank is measured by a pressure sensor 32. When the internal pressure change of the fuel tank is recognized to follow the internal pressure change of the canister with high correlation, the valve is determined to have a malfunction (fixed opening).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve abnormality diagnosis apparatus. In particular, the present invention relates to an apparatus for diagnosing a malfunction of a valve used in a fuel vapor purge system.

[0002]

2. Description of the Related Art Generally, a vehicle provided with a tank for volatile liquid fuel employs a so-called fuel vapor purge system. According to a typical purge system, fuel vapor generated in a fuel tank is once collected in a canister, and the collected fuel vapor is appropriately purged (discharged) into an intake passage of an engine. In addition, in order to ensure the reliability of the fuel vapor purge system, the system often incorporates a failure diagnosis device for finding leaks due to holes, tears, and the like. This failure diagnosis device is provided with, for example, a pressure sensor for detecting the internal pressure of a fuel tank and a region communicating with the fuel tank, and an electromagnetic valve provided in a passage connecting the fuel tank and the canister. Further, a diagnostic program for finding an abnormality (malfunction) of each device component such as the pressure sensor and the valve is incorporated in such a failure diagnosis device, thereby further ensuring the reliability of the purge system. .

[0003] For example, Japanese Patent No. 274169 discloses a device and a judgment method for diagnosing whether or not the above-described pressure sensor and electromagnetic valve are operating normally.
No. 9 is cited. This patent publication discloses an example of a method of detecting an abnormality of an electromagnetic valve (first control valve 24) provided in a passage connecting a fuel tank and a canister. According to this method, a valve closing signal (valve closing command) is given to the electromagnetic valve in a situation where a negative pressure is applied to the canister from the engine intake passage. If the tank internal pressure continues to decrease for more than the predetermined allowable time even though the electromagnetic valve should have been closed, the electromagnetic valve is stuck in the open state for some reason. It is presumed that the valve has become abnormal, and it is determined that the valve is abnormal (open abnormality).

[0004]

However, there are prerequisites to be satisfied in order to use the above-mentioned determination method. In other words, when judging the abnormality of the valve, it is confirmed in advance that the state of the engine or the vehicle is in a certain stable state, and the reliability of the abnormality diagnosis is ensured only when the prerequisite (the abnormality diagnosis permission condition) is satisfied. Is done. This is because, for example, in a situation where the vehicle is traveling on a rough road (uneven road, etc.) and the liquid level and the liquid area in the fuel tank fluctuate drastically, the tank internal pressure (fuel Evaporation)
Also fluctuate greatly. Under such a turbulent situation, it is not possible to make a correct determination even if an attempt is made to determine the presence or absence of a valve malfunction simply by monitoring only the temporal change of the tank internal pressure, and the possibility of erroneous determination is rather large. Under such circumstances, in the above-described conventional technology, diagnosis of the electromagnetic valve or the like is performed only after confirming that the state of the engine or the vehicle satisfies the abnormality diagnosis permission condition based on information from various sensors. Had been programmed.

[0005] However, as long as such a determination method is used, valve abnormality diagnosis cannot be performed unless the engine or vehicle strictly meets the abnormality diagnosis permission condition. This has potentially reduced the opportunity for anomaly diagnosis.

The present invention has been made in view of the above circumstances, and has as its object not to require strict prerequisites to be entered into the diagnostic process and to be relatively free from the prerequisites. Diagnosis can be performed frequently,
It is another object of the present invention to provide a valve abnormality diagnostic device having excellent diagnostic accuracy.

[0007]

According to the first aspect of the present invention, there is provided the following:
A first internal pressure detecting means for directly or indirectly detecting the internal pressure of the first space, which is a device for diagnosing an abnormality of a valve disposed in a path communicating the space and the second space, Second
Second internal pressure detecting means for directly or indirectly detecting the internal pressure of the space,
And a diagnostic control means capable of obtaining internal pressure information from the second internal pressure detecting means, wherein the diagnostic control means responds to a change in the internal pressure of the first space under a situation in which a valve closing command is issued to the valve. When a change in the internal pressure in the correlated second space is recognized, it is determined that a malfunction has occurred in the valve.

[0008] This diagnostic method is based on the fact that a change in the internal pressure in the second space, which correlates with a change in the internal pressure in the first space, is recognized even though the valve should be in the closed state. It is determined that a failure has occurred in the state. In the present invention, the change in the internal pressure in the first space and the change in the internal pressure in the second space are compared, that is, based on the relative relationship between the internal pressures in the two spaces, the malfunction of the valve interposed in the communication path between the two spaces is determined. The presence or absence can be determined. As long as it is guaranteed that the first space and the second space are in the same system (same system) and are subject to external influence (disturbance) under the same conditions, either one of the spaces is absolute Stable state is not required as a prerequisite for entering the diagnostic process. Therefore, according to the present invention, it is not necessary to establish strict prerequisites for entering the diagnosis process, and the failure diagnosis can be performed relatively frequently. In addition, since it is a diagnostic method that is hardly affected by disturbance in principle, the possibility of erroneous diagnosis is low and the diagnostic accuracy is excellent even when the system is under bad conditions.

According to a second aspect of the present invention, in the valve abnormality diagnosing device according to the first aspect, the diagnostic control means includes a first diagnostic control unit.
The internal pressure of the space is monitored for a change equal to or more than a first predetermined amount and the internal pressure of the second space for a change equal to or more than a second predetermined amount, and a correlation rate that is the frequency of occurrence of the latter with respect to the former is monitored. When the value is equal to or larger than a threshold value, it is determined that an operation failure has occurred in the valve.

According to this configuration, it is possible to determine the presence or absence of a valve operation failure by evaluating the correlation between the internal pressure change in the first space and the internal pressure change in the second space by a statistical method. That is, the correlation rate is a quantitative measure indicating the degree of follow-up of the change in internal pressure in the second space with respect to the change in internal pressure in the first space. Thus, it is determined that a malfunction has occurred in the valve. Therefore, the reliability of the diagnosis result is excellent.

According to a third aspect of the present invention, in the abnormality diagnostic apparatus for a valve according to the second aspect, the correlation rate indicates an effective number of times that the internal pressure of the second space can be changed by a second predetermined amount or more.
The internal pressure of the first space is divided by the number of times that the internal pressure has changed by a first predetermined amount or more.

This limits a specific calculation method for the correlation rate. The technical significance will be clear in the section of “Embodiments of the Invention” described later. Claim 4
In the valve abnormality diagnosis apparatus according to any one of claims 1 to 3, the first space is constituted by a canister, and the second space is constituted by a fuel tank. And

The fourth aspect of the present invention limits the valve abnormality diagnosis apparatus of the present invention to be suitable for abnormality diagnosis of a valve disposed in a path connecting a canister and a fuel tank in a fuel vapor purge system. is there. With the fuel vapor purge system equipped with such an abnormality diagnosis device,
System reliability is improved.

According to a fifth aspect of the present invention, in the valve abnormality diagnosing apparatus according to the fourth aspect, the first internal pressure detecting means for indirectly detecting the internal pressure of the canister as the first space is provided from the canister to the engine. A purge flow rate calculating means for calculating a purge flow rate of gas to the intake passage, and a canister internal pressure calculating means for calculating a simulated canister internal pressure based on the purge flow rate and an operation characteristic of an atmospheric valve of the canister. I do.

According to this configuration, the atmospheric valve operating characteristics of the canister held by the canister internal pressure calculation means as internal data based on the gas purge flow rate calculated by the purge flow rate calculation means already existing in the fuel vapor purge system. , The simulated canister internal pressure can be calculated by calculation. Therefore, it is not necessary to dispose a pressure sensor or the like for directly detecting the internal pressure of the canister as the first space in the canister, and it is possible to avoid complication of the fuel vapor purge system.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific example of a fuel vapor purging system for a vehicle and a failure diagnosis apparatus therefor will be described below with reference to the drawings.

As shown in FIG. 1, the engine 10 includes a combustion chamber 11, an intake passage 12, and an exhaust passage 13. When the engine 10 is operated, the fuel (for example, gasoline) stored in the fuel tank 30 is pumped by the fuel pump 31 and delivered through the fuel supply passage.
After being sent to 2a, it is injected and supplied into the intake passage 12 by the fuel injection valve 12b. A throttle valve 12c is provided upstream of the intake passage 12 to change the flow passage area of the intake passage 12 based on a depression operation of an accelerator pedal (not shown). Further upstream, an air cleaner 12d for purifying intake air and an engine 1
Air flow meter 1 for detecting the amount of intake air to zero
2e is provided.

The fuel vapor purge system 20 includes a canister 40 for collecting fuel vapor generated from the fuel tank 30.
(First space) and a purge passage 71 for purging the collected fuel vapor into the intake passage 12 of the engine 10. In the purge system 20, a pressure sensor 32 as second internal pressure detecting means and a breather control valve 33 are provided on a ceiling portion of the fuel tank 30 (second space). The pressure sensor 32 detects or measures the pressure in the fuel tank 30 and a region communicating with the fuel tank 30. The breather control valve 33 is a diaphragm type differential pressure valve, and is opened only when the internal pressure of the fuel tank becomes higher than the pressure in the breather passage 34 by a predetermined pressure or more, such as during refueling, and the fuel vapor is passed through the breather passage 34 to the canister. Release to 40.

Further, the space in the fuel tank 30 can communicate with the canister 40 via a vapor passage 35 having a smaller passage inner diameter than the breather passage 34. The tank internal pressure control valve 60 provided between the vapor passage 35 and the canister 40 is a diaphragm type differential pressure valve having substantially the same function as the breather control valve 33 described above. The diaphragm 61 in the tank internal pressure control valve 60 opens the tank internal pressure control valve 60 only when the pressure in the fuel tank 30 becomes higher than the pressure in the canister 40 by a predetermined pressure or more.

The canister 40 is provided with an adsorbent (for example, activated carbon) therein, and temporarily stores fuel vapor by adsorbing the adsorbent on the adsorbent, and is then placed under a pressure lower than the atmospheric pressure. The fuel vapor adsorbed on the material is capable of being desorbed again. Hereinafter, in this specification, a pressure lower than the atmospheric pressure is referred to as negative pressure, and a pressure higher than the atmospheric pressure is referred to as positive pressure. The canister 40 communicates with the fuel tank 30 via a breather passage 34 and a vapor passage 35,
It can communicate with the intake passage 12 via the purge passage 71, and further communicates with the atmosphere introduction passage 72 and the atmosphere discharge passage 73 via the atmosphere valve 70. Note that the purge passage 71
Is provided with a purge control valve 71a composed of a solenoid valve. An air introduction valve 72a composed of a solenoid valve is provided in the middle of the air introduction passage 72 communicating with the air cleaner 12d.

In the atmosphere valve 70, two diaphragms 74 and 75 each having a different valve function are provided. The first diaphragm 74 has a space 74 on the rear side thereof.
a communicates with the purge passage 71, and when the purge passage 71 is in a negative pressure state below a predetermined pressure, the valve is opened to open the air introduction passage 7.
2 allows the outside air to flow into the canister 40. On the other hand, the second diaphragm 75 opens when the pressure inside the canister 40 reaches a positive pressure equal to or higher than a predetermined pressure, and discharges excess air from the canister 40 to the atmosphere discharge passage 73.

The interior of the canister 40 is divided by a partition plate 41 into a first adsorbent chamber 42 and a second adsorbent chamber 43. Although both the adsorbent chambers 42 and 43 are filled with an adsorbent (activated carbon), both chambers communicate with each other via a gas permeable filter 44 at the bottom of the canister. The fuel tank 30 is connected via a vapor passage 35 and a tank internal pressure control valve 60 on the one hand, and a breather control valve 33 and a breather passage 34 on the other hand.
Can be connected to the first adsorbent chamber 42 via the The atmosphere introduction passage 72 and the atmosphere discharge passage 73 are provided with the atmosphere valve 7.
0 can communicate with the second adsorbent chamber 43.
A purge passage 71 having a purge control valve 71a
The first adsorbent chamber 42 of the canister 40 and the intake passage 1
The first adsorbent chamber 42 communicates with the downstream position of the throttle valve 12c in accordance with the opening operation of the purge control valve 71a. That is, the fuel vapor introduced from the vapor passage 35 or the breather passage 34 is temporarily adsorbed by the first adsorbent chamber 42 and then carried to the purge passage 71. Further, even when the second diaphragm 75 provided in the atmosphere valve 70 is opened and excess air in the canister 40 is discharged from the atmosphere discharge passage 73, the fuel remaining in the gas in the canister 40 can be obtained. When the vapor passes through the first adsorbent chamber 42 and the second adsorbent chamber 43, it is adsorbed by the adsorbent therein and does not leak out.

In addition, the fuel vapor purge system 20 includes
A negative pressure introducing passage 80 is provided so as to communicate between the tank internal pressure control valve 60 and the second adsorbent chamber 43 side of the canister 40. In the middle of the negative pressure introducing passage 80, a negative pressure introducing control valve 80a (valve to be diagnosed in this example) composed of an electromagnetic valve is provided. This negative pressure introduction control valve 80a
Is opened, the inside of the tank internal pressure control valve 60 and the second adsorbent chamber 43 are directly communicated via the negative pressure introducing passage 80. In particular, when the negative pressure introduction control valve 80a is opened in a state where the purge control valve 71a is in the open state and a negative pressure is introduced into the canister 40, the space in the purge passage 71 becomes the first space. The adsorbent chamber 42 → the air permeable filter 44 → the second adsorbent chamber 43 → the negative pressure introducing passage 80 → the tank internal pressure control valve 60 → communicate with the fuel tank 30 via the vapor passage 35 Further, since the space in the breather passage 34 is also in communication with the first adsorbent chamber 42, the same space as the purge passage 71 is shared.

As described above, by opening the negative pressure introduction control valve 80a while the negative pressure is being introduced into the canister 40, the shared space in the fuel vapor purge system 20 which communicates with each other is established in the same system 20. It will be the evaporative route.
The failure diagnosis device for the fuel vapor purge system according to the present embodiment determines whether or not there is a failure by determining whether or not there is a leak in the evaporation path. At the same time, the failure or malfunction of the negative pressure introduction control valve 80a is also diagnosed.

Further, the engine 10 and the fuel vapor purge system 20 include an electronic control unit (ECU) 50 which plays a role as a control system and a diagnostic system of the engine. As shown in FIGS. 1 and 2, outputs from various sensors including the pressure sensor 32 and the air flow meter 12e are input to the ECU 50. The ECU 50 drives and controls the fuel injection valve 12b, the fuel pump 31, the purge control valve 71a, the atmosphere introduction valve 72a, the negative pressure introduction control valve 80a, etc., and performs a diagnosis process regarding the presence or absence of leakage in the evaporation path and the negative pressure introduction control. A failure diagnosis process for the valve 80a is executed.

As shown in FIG. 2, the ECU 50 includes a CPU 51a for executing various processes related to the control and diagnosis, a ROM 51b as a read-only memory storing various programs related to the control and diagnosis, and a volatile memory that can be freely read and written. The microcomputer 51 mainly includes a RAM 51c which is a memory and a backup RAM 51d which is a non-volatile memory in which reading and writing are free and the contents of the battery are stored even after the engine 10 is stopped by being backed up by a battery. I have. The microcomputer 51 further includes a first counter 5
2, a second counter 53 and an internal timer 54 are incorporated. However, when the internal register of the CPU 51a is to serve as a counter, the first and second counters 5 are used.
There is no need to dare provide 2,53. On the input side of the microcomputer 51, in addition to the pressure sensor 32 and the air flow meter 12e, various sensors necessary for operation control of the engine 10, such as a rotation speed sensor and a cylinder discrimination sensor, are directly or indirectly connected. . Microcomputer 5
1, the fuel injection valve 12b, the fuel pump 31,
The purge control valve 71a, the atmosphere introduction valve 72a, and the negative pressure introduction control valve 80a are connected via respective drive circuits. The ECU 50 executes engine control such as fuel injection control and air-fuel ratio control based on various information provided from each sensor. In addition, the ECU 50 recognizes the output signal from the pressure sensor 32 and appropriately performs opening / closing control of the purge control valve 71a, the atmosphere introduction valve 72a, and the negative pressure introduction control valve 80a to execute a failure diagnosis of the purge system. In order to accurately perform a failure diagnosis of the purge system, a failure diagnosis of the negative pressure introduction control valve 80a is particularly performed. In this sense, the ECU 50 is positioned as “diagnosis control means”.

(Outline of Fuel Purge by Fuel Vapor Purge System 20) When the fuel in the fuel tank 30 vaporizes and its vapor pressure reaches a predetermined pressure or more, the tank internal pressure control valve 60
Is opened to allow fuel vapor to flow from the fuel tank 30 into the canister 40. Further, for example, when the vapor pressure of the fuel vapor suddenly increases in the fuel tank 30, such as during fueling, the breather control valve 33 is opened,
A larger flow of fuel vapor from the fuel tank 30 into the canister 40 is allowed. The fuel vapor flowing into the canister 40 is temporarily adsorbed by the adsorbent in the canister 40. Thereafter, for example, as shown in FIG.
Is equal to the predetermined purge start water temperature (8 in this embodiment).
When the temperature reaches 0 ° C.), the purge control valve 71a and the atmosphere introduction valve 72a are appropriately opened based on a control signal from the ECU 50. Then, through the purge passage 71, the intake passage 1
2, the intake negative pressure is introduced into the canister 40,
Fresh air is introduced into the canister 40 from the air cleaner 12d through the atmosphere introduction passage 72. The fuel vapor is released from the adsorbent by the introduction of the negative pressure and the fresh air, and is purged to the intake passage 12 through the purge passage 71.

(Outline of Leakage Diagnosis of Evaporative Path of Fuel Vapor Purge System 20) In performing leakage diagnosis of the evaporative path, the cooling water temperature of the engine 10 reaches the purge start water temperature and the purge is started. A precondition is that the internal pressure is stable. For example, as shown in FIG. 3, based on the pressure detected by the pressure sensor 32, the pressure change amount ΔP1 of the tank internal pressure for a predetermined time (for example, 15 seconds).
Is calculated, and if it is confirmed three consecutive times that the pressure change amount ΔP1 is equal to or less than the predetermined value, it is determined that the tank internal pressure is stable. At the point in time when the preconditions for the leak diagnosis are satisfied (time t0), the air introduction valve 72a is closed and the purge control valve 71 is closed by a command from the ECU 50.
a and the negative pressure introduction control valve 80a are opened. As a result, the canister 40 is shut off from the atmosphere, and a negative pressure is led from the intake passage 12 to the canister 40 via the purge passage 71. In addition, by opening the negative pressure introduction control valve 80a, the fuel tank 30, the canister 40, the breather passage 34, the vapor passage 35, and the purge passage 71 (that is, the entire inside of the evaporation passage) are brought into a negative pressure state. The internal pressure of the evaporative passage is measured by a pressure sensor 3 on the ceiling of the fuel tank 30.
2 detected.

If the purge control valve 71a is once closed at time t1 under a condition where the pressure in the entire evaporation path is reduced to some extent, the inside of the evaporation path is closed in a negative pressure state. At this time, if there is no abnormality such as a hole in the evaporation path, the fuel tank 3
As the fuel in the evaporator evaporates, the internal pressure of the evaporative passage should gradually approach (slowly increase) the equilibrium pressure of the air and fuel vapor remaining in the evaporative passage. On the other hand, if there is a leak in the evaporative path, the internal pressure in the evaporative path rapidly approaches the external pressure (atmospheric pressure). In any case, the evaporative path internal pressure increases after time t1,
The degree of internal pressure rise differs depending on the presence or absence of leakage. In the present embodiment, the internal pressure of the evaporation path is again reduced to the predetermined negative pressure (−2.00
(kPa = −15 mmHg), at time t2,
Pressure change rate ΔP (−15) as pressure change degree
(KPa / sec or mmHg / sec). Then, based on the pressure change rate ΔP (−15), it is determined whether or not there is an abnormality such as a hole in the evaporation path.

(Failure Diagnosis of Valves Constituting Fuel Vapor Purging System 20) In order for the leakage diagnosis of the evaporative path to be reliable, the sensors and valves constituting the system operate normally. You need to make sure that it is always. Hereinafter, a method of diagnosing a malfunction of the negative pressure introduction control valve 80a provided in the negative pressure introduction passage 80 will be particularly described. In an actual system, abnormality diagnosis is performed for other valves and the pressure sensor 32, but the description thereof is omitted.

FIGS. 4 and 5 are flowcharts showing the outline of a valve failure diagnosis routine for diagnosing or judging the presence or absence of a malfunction of the negative pressure introduction control valve 80a. This routine is executed by the ECU 50 for a predetermined time (for example, several tens to
This is executed as a periodic interrupt process every several hundred milliseconds). The diagnosis process is particularly for detecting a defect (open fixation) in which the negative pressure introduction control valve 80a is fixed in the open state. Therefore, before entering the failure diagnosis routine, the ECU 50 sends a valve closing drive signal (valve closing) to the negative pressure introduction control valve 80a under the condition that the purge control valve 71a is open and the atmosphere introduction valve 72a is closed. Order) is issued.

When there is the interrupt processing request, the ECU 50
First, in step 101, the purge flow rate PQ is calculated. “Purge flow rate” means the flow rate of gas discharged to the exhaust passage 13 via the purge passage 71. The purge flow rate PQ depends on the valve opening of the purge control valve 71 a and the purge passage 7.
If the degree of the negative pressure of 1 is known, it can be calculated based on these, by calculation, or by referring to a characteristic map obtained by experiment or computer simulation. Here, the purge control valve 71a is connected to the ECU 5
Since the opening is controlled by 0, the ECU 50 holds information on the valve opening of the purge control valve 71a as internal data. On the other hand, the degree of the negative pressure in the purge passage 71 is correlated with the engine load, and the relationship between the two is formed into a characteristic map through experiments and computer simulations for each vehicle. The engine load can be calculated based on the rotation speed data from the engine rotation speed sensor and the intake air amount data from the air flow meter 12e. That is, the degree of the negative pressure in the purge passage 71 can also be grasped based on data from various sensors, and the purge flow rate PQ can be calculated based on the external data and the internal data. In this sense, the engine speed sensor and the air flow meter 12e
And the ECU 50 constitute "purge flow rate calculating means".

In step 102, the ECU 50 calculates a simulated canister internal pressure Pc. In this step, since the pressure sensor for directly detecting the internal pressure is not attached to the canister 40, the internal pressure of the canister is estimated based on other obtainable information. The estimated value is the simulated canister internal pressure Pc. There is a close correlation between the internal pressure of the canister and the purge flow rate PQ according to the characteristics of the atmospheric valve 70 of the canister, and the relationship between the two is mapped into characteristics through experiments and computer simulations for each vehicle. . The characteristic map is ECU5
0 is held as internal data, and by referring to it, the simulated canister internal pressure Pc can be calculated from the purge flow rate PQ obtained in the previous step. In this sense, the ECU 50 constitutes “canister internal pressure calculation means”. Then, the purge flow rate calculating means and the canister internal pressure calculating means constitute first internal pressure detecting means for indirectly detecting the internal pressure of the canister as the first space.

In step 103, it is determined whether or not the elapsed time from the previous zero clear of the internal timer 54 has reached a predetermined time TM (for example, 15 seconds). If the predetermined time TM has elapsed at that time, the processing of step 104 is executed, but if the predetermined time TM has not been reached, the processing of step 104 is skipped. That is, the process of step 104 is performed every predetermined time TM (for example, 15 seconds).

Step 104 is a reset operation every predetermined time TM. Here, first, the internal timer 54 is cleared to zero. Further, the simulated canister internal pressure Pc obtained in step 102 is set as the provisional canister reference internal pressure Pcs, and the detection pressure (tank internal pressure Pt) of the pressure sensor 32 at that time is set as the provisional tank reference internal pressure Pts. That is, the simulated canister internal pressure Pc after the lapse of the predetermined time TM is compared with the provisional comparison reference value (or reference point).
In addition to storing as Pcs, the tank internal pressure Pt at the elapse of the predetermined time TM is compared with a reference value (or reference point) P for provisional comparison.
This is stored as ts (see FIG. 6). That is, in step 104, the provisional canister reference internal pressure Pcs and the provisional tank reference internal pressure Pts are updated every predetermined time TM.

Steps 105 to 107 are a series of processes for counting the number of times the simulated canister internal pressure Pc has changed from the provisional canister reference internal pressure Pcs by a predetermined pressure value α or more. Specifically, in step 105, the absolute value of the difference ΔPc between the simulated canister internal pressure Pc and the provisional canister reference internal pressure Pcs at that time, that is, the absolute value of the amount of change in the canister internal pressure from the reference point is determined by the predetermined pressure value α ( For example, it is determined whether or not 0.67 kPa = 5.0 mmHg) or more. If the determination at step 105 is YES (Yes), at step 106, the value C1 of the first counter 52 assigned for counting the number of canister internal pressure changes is incremented (addition of 1). Similarly to the above, zero clear of the internal timer 54 and resetting of the provisional canister reference internal pressure Pcs are performed (see FIG. 6). The predetermined pressure value α is set to such a value that a change in the simulated canister internal pressure Pc, which is only a slight fluctuation, can be excluded from the count target.

If the determination in step 105 is NO (No), the simulated canister internal pressure Pc and the tank internal pressure Pc
without checking the amount of change in t at all (that is, without performing any addition or subtraction of the first and second counters 52 and 53),
Skip to step 113. This is because if the change in the simulated canister internal pressure Pc is too small, it is not appropriate to rely on the valve operation failure determination method of the present invention.

After step 107, the process proceeds to step 108 in FIG. In step 108, the absolute value of the difference ΔPt between the tank pressure Pt at that time and the provisional tank reference pressure Pts, that is, the absolute value of the amount of change in the tank pressure from the reference point is determined by a predetermined pressure value β (for example, 0.47 kPa = 3). 0.5mm
Hg) is determined. If the determination in step 108 is YES, in step 109, the second counter 53 assigned for counting the number of changes in the tank internal pressure is used.
Is incremented (1 added). In other words, if the determination in step 105 is YES and the determination in step 108 is YES, it is determined that the followability corresponding to the change in Pt with respect to the change in Pc is recognized (positive affirmation of the followability), and the counter values C1, C2 Is the result of adding 1 to both. The predetermined pressure value β is set to a value smaller than the value α (β <α).

On the other hand, if the determination in step 108 is NO, in step 110, the absolute value of the difference ΔPt between the tank internal pressure Pt and the provisional tank reference internal pressure Pts, that is, the absolute value of the amount of change in the tank internal pressure from the reference point is determined. , Predetermined pressure value γ
(For example, 0.11 kPa = 0.8 mmHg). If the determination in step 110 is YES, in step 111, the value C of the second counter 53 is set.
Decrement 2 (subtract 1). That is, step 1
If the determination at step 05 is YES and the determination at step 110 is YES, it is determined that a clear change in Pt is not recognized despite a sufficient change in Pc (aggressive denial of change in tracking), and the counter value C1 is determined. The result is that the counter value C2 is minus one despite the increase of The predetermined pressure value γ is set to a value smaller than the value β (γ <
β).

When the determination in step 110 is NO, that is, when γ ≦ ΔPt <β, the addition / subtraction of the second counter 53 is not performed at all. In other words, in this case, the change in Pt is halfway despite a sufficient change in Pc, and it is not possible to positively affirm or deny the followability of the change in Pt to the change in Pc. Therefore, the counter value C1
The result is that the counter value C2 is maintained as it is despite the increase of the counter value.

After the processing in step 109, 110 or 111, in step 112, the ECU 50 resets the provisional tank reference internal pressure Pts in the same manner as in step 104, and prepares for the determination in the next cycle. Step 11
After 2 or after the determination of step 105 is NO, the process proceeds to a final determination procedure of step 113 and subsequent steps.

In step 113, the value C of the first counter
It is determined whether 1 is equal to a predetermined determination value DA (for example, 10 times). If the first counter value C1 is less than the determination value DA, it is considered that the number of changes of the simulated canister internal pressure Pc has not reached the specified number and it is not in a state where proper failure diagnosis can be performed, and a malfunction occurs in the valve. The interruption process of FIG. 4 and FIG. That is, the determination value DA is equal to Pt with respect to the change in Pc.
Is a value that can be called the minimum specified number of times for ensuring statistical reliability in determining the follow-up performance of the change of the data. Of course,
Increasing the determination value DA statistically increases the reliability of the determination, but on the other hand, it takes a long time to reach a conclusion.

If the determination in step 113 is YES (C1
= DA), it is determined that the number of changes in the simulated canister internal pressure Pc has reached the specified number of times for performing proper failure diagnosis, and the determination in step 114 is performed. That is, in step 114,
The value C2 of the second counter is equal to a predetermined determination value DB (for example, 7
Times) or not. The determination value DB is set to a value equal to (DB = DA) or a value close to the determination value DA (DB <DA).

If the determination in step 114 is YES, it is determined that the negative pressure introduction control valve 80a is open and has a failure (open failure) (step 115). Satisfaction of the determination condition of step 114 means that the number of changes C2 in the tank internal pressure is equal to or very close to the number of changes C1 in the canister internal pressure, and the change in the simulated canister internal pressure Pc and the change in the tank internal pressure Pt are satisfied. This is because there is a high correlation with the trend, that is, it is possible to rationally determine the ability of the Pt change to follow the Pc change. Then, a negative pressure introduction control valve 8 provided in a passage connecting the fuel tank 30 and the canister 40 is provided.
If there is a close correlation between the changes in the two internal pressures Pc and Pt even though the valve closing command is issued at 0a, it means that the two regions are clearly in communication with each other. It can be determined that there is a high possibility that the pressure introduction control valve 80a is out of order and malfunctioning. In this case, the processing of steps 113 and 114 is
/ DA is calculated, and the correlation rate R is equal to or greater than a predetermined threshold value (7/10 = 70 in this example).
% Or more), it can be understood that the process determines that the negative pressure introduction control valve 80a is in the open failure state. When an open failure is determined, a warning display (for example, installed in an instrument panel of a vehicle) for notifying a person of the failure of the fuel vapor purge system is turned on.

On the other hand, if the determination in step 114 is NO,
It is determined that the negative pressure introduction control valve 80a has no failure in the open state (normal) (step 116). This is so regarded as a flip in case of an open fault. That is, the fact that the determination condition of step 114 is not satisfied means that the change in the simulated canister internal pressure Pc and the tank internal pressure Pc are not satisfied.
This is because there is no significant correlation with the change trend of t, that is, it cannot be asserted that the followability of the Pt change to the Pc change is reasonably recognized. In terms of the scale of the correlation rate R, the ratio R has not reached a predetermined threshold value (70% in this example). Therefore, it cannot be said that the negative pressure introduction control valve 80a is in the open failure state and the fuel tank 30 and the canister 40 are in communication with each other.
It is passively determined that the valve is normally closed according to the valve closing command from 0. Incidentally, when the negative pressure introduction control valve 80a is normally closed, the fuel tank 30 should be an isolated space, in which case the tank internal pressure Pt
Should maintain a substantially constant value as shown by the dashed line in FIG.

The predetermined time TM in step 103
Can be understood as the time limit until zero clearing of the timer and resetting of the provisional reference internal pressures Pcs and Pts in step 104 when the determination in step 105 does not easily become YES. 4 and 5
In the diagnosis procedure, if the variation ΔPc of the simulated canister internal pressure is not equal to or greater than the predetermined pressure value α within the time limit, it is determined that a meaningful (or suitable for diagnosis) change in the simulated canister internal pressure cannot be obtained, and the counting is performed. Repeat the diagnosis without changing the value. In other words, it is meaningless if it takes a long time for the determination of step 105 to become YES. A preferable range of the predetermined time TM as the time limit is:
Empirically in the range of 10-20 seconds (preferably around 15 seconds)
It is.

(Effects) According to the present embodiment, the following effects can be obtained. In the present embodiment, the valve to be diagnosed (negative) is determined based on the presence or absence of the tank internal pressure Pt following the change in the simulated canister internal pressure Pc or the close correlation between the Pc change and the Pt change. The presence or absence of an open failure of the pressure introduction control valve 80a) is diagnosed. That is, regardless of the absolute value of Pt, it is possible to diagnose the presence or absence of a valve opening failure by focusing only on the relative relationship between Pc and Pt. Therefore, unlike the prior art, the fact that the vehicle, engine or tank internal pressure Pt is in a predetermined stable state is not required as a precondition for entering the diagnostic process. In other words, valve failure diagnosis can be performed even when the vehicle is traveling on a rough road.
Therefore, according to the present embodiment, the failure diagnosis can be performed at any time (or frequently) without being restricted by the establishment of the strict precondition.

Even if it is determined that the valve to be diagnosed is in the open failure state, the correlation between the change in the simulated canister internal pressure Pc and the change in the tank internal pressure Pt is statistically reasonable. Is determined as a condition for judgment. That is, the valve open failure is determined only when the correlation rate R is large enough to be statistically certain. Therefore, the accuracy and reliability of the valve failure diagnosis are excellent.

In this embodiment, since the simulated canister internal pressure is calculated based on the purge flow rate, it is not necessary to provide another pressure sensor for measuring the pressure in the canister 40, and the airtightness thereof is ensured. Can be suppressed from increasing due to an increase in the number of assembling man-hours required.

(Another Example) The above embodiment may be modified as follows. In the above embodiment, the simulated canister internal pressure is calculated based on the purge flow rate in a state where the valve closing command has been issued to the negative pressure introduction control valve 80a in advance, and the change in the simulated canister internal pressure and the change in the actually measured tank internal pressure are calculated. Negative pressure introduction control valve 8 based on
0a, the negative pressure introduction control valve 8
0a is opened to calculate the simulated tank internal pressure based on the purge flow rate assuming a state in which the canister 40 and the fuel tank 30 are connected to each other, and a negative pressure is calculated based on the change in the simulated tank internal pressure and the change in the actually measured tank internal pressure. An abnormality diagnosis of the pressure introduction control valve 80a may be performed.

A second pressure sensor is provided in the canister 40 without actually relying on the simulated canister internal pressure Pc which is an estimated value of the internal pressure based on indirect data, and the canister internal pressure is measured (directly detected). You may do so. In this case, the second pressure sensor serves as first internal pressure detecting means.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fuel vapor purge system and a failure diagnosis device thereof.

FIG. 2 is a block diagram showing an outline of an electrical configuration related to failure diagnosis.

FIG. 3 is a timing chart showing an outline of a leak diagnosis of the purge system.

FIG. 4 is a flowchart of a valve failure diagnosis procedure according to one embodiment.

FIG. 5 is a flowchart of a valve failure diagnosis procedure according to one embodiment.

FIG. 6 is a timing chart showing several patterns relating to the correlation between the internal pressure of the canister and the internal pressure of the tank when the valve is abnormal.

[Explanation of symbols]

Reference Signs List 10: engine, 12: intake passage, 12e: air flow meter (first internal pressure detecting means), 20: fuel vapor purge system, 30: fuel tank (second space), 32: pressure sensor (second internal pressure detection) Means), 40 ... canister (first space), 50 ... ECU (first internal pressure detecting means and diagnostic control means), 51 ... microcomputer, 5
2, 53: first and second counters, 54: internal timer,
71: purge passage, 70: atmosphere valve, 71a: purge control valve, 80: negative pressure introduction passage, 80a: negative pressure introduction control valve (valve to be diagnosed).

Continuing from the front page (72) Inventor Shuichi Hanai 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. F-term (reference) 3G044 BA23 CA12 DA02 DA04 EA32 EA55 EA64 FA03 FA04 FA08 FA13 FA36 GA01 GA02 GA04 GA06 GA10 GA16 GA20 GA22 GA24 GA27 3G084 BA27 DA33 EA07 EA11 FA00 FA20 3G301 HA01 HA14 JB02 JB10 KB09 LB00 LC01 LC07 NA01 NC02 NE23 PA01Z PB00Z PB09A PB09Z PE01Z

Claims (5)

[Claims] An apparatus for diagnosing an abnormality of a valve disposed on a path connecting a first space and a second space, wherein the device diagnoses an internal pressure of the first space directly or indirectly. 1 internal pressure detecting means, 2nd internal pressure detecting means for directly or indirectly detecting the internal pressure in the second space, and internal pressure information from the first and second internal pressure detecting means while controlling the drive of the valve. Diagnostic control means that can obtain the internal pressure change in the second space that correlates with the internal pressure change in the first space under the condition that a valve closing command is issued to the valve. An abnormality diagnosis device for a valve, characterized in that when it is recognized, it is determined that a malfunction has occurred in the valve. 2. The diagnostic control means according to claim 1, wherein a change in the internal pressure of the first space by a first predetermined amount or more, a change in the internal pressure of the second space by a second predetermined amount or more, and a frequency of occurrence of the latter with respect to the former. The valve abnormality diagnosis apparatus according to claim 1, wherein a certain correlation rate is monitored, and when the correlation rate becomes equal to or more than a predetermined threshold value, it is determined that the valve is malfunctioning. 3. The correlation ratio is obtained by dividing the effective number of times that the internal pressure of the second space has changed by a second predetermined amount or more by the number of times that the internal pressure of the first space has changed by a first predetermined amount or more. The abnormality diagnostic device for a valve according to claim 2, wherein: 4. The first space is constituted by a canister,
The valve abnormality diagnostic device according to any one of claims 1 to 3, wherein the second space is configured by a fuel tank. 5. A purge flow rate calculating means for indirectly detecting an internal pressure of a canister as a first space, wherein said first internal pressure detecting means calculates a purge flow rate of gas from a canister to an intake passage of an engine; 5. The valve abnormality diagnostic device according to claim 4, further comprising: a canister internal pressure calculating means for calculating a simulated canister internal pressure based on a purge flow rate and an operation characteristic of an atmospheric valve of the canister.