JPH11210569A - Abnormal condition diagnostic device for evaporated gas purge system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration in drivability and to detect an abnormal condition in an early stage by finding evaporation gas concentration from a ratio between an air-fuel ratio feedback correction quantity deviation and a purge rate, comparing an evaporation gas concentration changing quantity and the evaporation gas concentration with determination values, and determining execution/stop of abnormal condition diagnosis. SOLUTION: In abnormal condition diagnosis for an evaporation gas purge system 21, it is determined whether an evaporation gas generation quantity (an evaporation gas adsorption quantity inside a canister 23) is low or not by determining whether an evaporation gas concentration changing quantity, which is found on the basis of a ratio between an air-fuel ratio feedback correction quantity deviation and a final purge rate, and the evaporation gas concentration are below the predetermined values or not when an execution condition is established while a prohibition condition is not established. According to the current cooling water temperature and the like, a determination value is set from a map, and if NO is determined, that is, if the evaporation gas generation quantity is high, abnormal condition diagnosis is prohibited. If the evaporation gas generation quantity is low, a purge control valve 31 and a canister closing valve 26 are operated when the absolute value of atmospheric pressure variation is a predetermined value or less, and processes in four steps are carried out while performing determination of the processing steps and abnormal condition diagnosis is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention diagnoses whether there is an abnormality in an evaporative gas purge system for purging (ejecting) evaporative gas (fuel evaporative gas) generated by evaporating fuel in a fuel tank into an intake pipe of an internal combustion engine. The present invention relates to an abnormality diagnosis device for an evaporative gas purge system.

[0002]

2. Description of the Related Art Conventionally, in an evaporative gas purge system, in order to prevent evaporative gas generated in a fuel tank from leaking into the atmosphere, the evaporative gas is adsorbed into a canister through an evaporative gas passage in the fuel tank. A purge control valve is provided in the middle of a purge passage for purging evaporative gas adsorbed to the intake pipe of the internal combustion engine, and the opening and closing of the purge control valve is controlled according to the operation state of the internal combustion engine, so that the canister can be connected to the intake pipe. The purge flow rate of the evaporative gas to be purged is controlled. It is necessary to detect the evaporative gas leakage early so as to prevent the evaporative gas purge system from leaking into the atmosphere abnormally for a long time.

Therefore, as shown in, for example, Japanese Patent Application Laid-Open No. 5-125997, the pressure of the evaporative gas purge system when the atmospheric pressure or the negative pressure of the intake pipe is introduced and sealed in the evaporative gas purge system or the amount of subsequent pressure change is reduced. In some cases, the presence or absence of an abnormality such as pressure leak of the evaporative gas purge system is diagnosed on the basis of this.

However, when the abnormality diagnosis is performed and the intake pipe negative pressure is introduced into the evaporative gas purge system when the amount of evaporative gas generated in the evaporative gas purge system is large, over-rich occurs due to the inflow of the evaporative gas into the intake pipe. And drivability and exhaust emission may be degraded.

As a countermeasure against this, Japanese Patent Application Laid-Open No. 9-177617
As described in the publication, when the cumulative execution time of purge or the integrated purge amount after engine start is equal to or less than a predetermined value, or when the air-fuel ratio feedback correction amount is equal to or more than a predetermined value, the abnormality diagnosis of the evaporative gas purge system is stopped. Has been proposed.

[0006]

However, even when the air-fuel ratio feedback correction amount is equal to or more than a predetermined value, if the amount of evaporative gas generated in the evaporative gas purge system is small, even if an abnormality diagnosis of the evaporative gas purge system is executed. , Not overrich. Further, since the evaporative gas generation amount estimated from the accumulated purge execution time and the accumulated purge amount has a large error, if the execution / stop of the abnormality diagnosis is determined on the basis of the judgment in consideration of the error, the abnormality diagnosis suspension period becomes long. For this reason, even when the abnormality diagnosis can be performed, the abnormality diagnosis may be stopped, and the frequency of performing the abnormality diagnosis may decrease, and the detection of the abnormality may be delayed.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and accordingly, has as its object to stop the abnormality diagnosis of the evaporative gas purge system when the amount of evaporative gas generated in the evaporative gas purge system is large. In order to provide an abnormality diagnosis device for an evaporative gas purge system that can prevent deterioration of drivability and exhaust emission and execute abnormality diagnosis at other times to detect an abnormality of an evaporative gas purge system at an early stage. is there.

[0008]

According to a first aspect of the present invention, an abnormality diagnosing device for an evaporative gas purge system comprises: an air-fuel ratio feedback correction amount deviation; Is determined from the ratio, and both the change amount of the evaporative gas concentration and the change amount of the evaporative gas concentration or the change amount of the evaporative gas concentration are compared with a determination value, and execution / stop of the abnormality diagnosis is determined by the execution condition determining means. Here, when the amount of evaporative gas generated increases, the amount of change in evaporative gas concentration increases. Therefore, if the execution / cancellation of the abnormality diagnosis is determined using the amount of change in evaporative gas concentration, the evaporative gas is generated when the amount of evaporative gas generated is large. Abnormality diagnosis of the gas purge system can be stopped to prevent deterioration of drivability and exhaust emission. At other times, abnormality diagnosis can be performed to detect abnormality of the evaporative gas purge system at an early stage. Since the evaporative gas concentration is also a parameter that reflects the amount of evaporative gas generated, like the amount of evaporative gas change, the execution of the abnormality diagnosis using both the evaporative gas concentration change and the evaporative gas concentration is performed.
If the cancellation is determined, the execution / stop of the abnormality diagnosis can be determined with higher accuracy.

In this case, the determination value is set as follows:
The determination value setting means may set the temperature based on at least one of the cooling water temperature, the elapsed time after starting, and the purge execution integrated time. With this configuration, an optimum determination value can be set according to the cooling water temperature, the elapsed time after the start, and the accumulated purge execution time, and the determination accuracy can be improved.

Further, when the execution / stop of the abnormality diagnosis is determined by comparing the evaporative gas concentration with the determination value, the determination value is determined based on the cooling water temperature, the elapsed time after starting, and the purge execution integrated time. May be set by the determination value setting means based on at least one of the following. If you do this,
Even when the execution / stop of the abnormality diagnosis is determined from the evaporative gas concentration, the execution / stop of the abnormality diagnosis can be accurately determined.

According to a fourth aspect of the present invention, the detected value of the pressure change amount of the evaporative gas purge system may be corrected by the detected value correcting means based on at least one of the evaporative gas concentration and the change amount of the evaporative gas concentration. . By doing so, the accuracy of the detection value of the pressure change amount can be improved,
Abnormality diagnosis accuracy can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
17 through FIG. First, a schematic configuration of the entire system will be described with reference to FIG. An air cleaner 13 is provided upstream of an intake pipe 12 of an engine 11 which is an internal combustion engine.
The air that has passed through the air cleaner 13 is sucked into each cylinder of the engine 11 through the throttle valve 14. The opening of the throttle valve 14 is adjusted by the amount of depression of an accelerator pedal 15. The intake pipe 12 is provided with a fuel injection valve 16 for each cylinder. Fuel (gasoline) in a fuel tank 17 is sent to each fuel injection valve 16 via a fuel pipe 19 by a fuel pump 18. The fuel tank 17 includes the fuel tank 1
Pressure sensor 2 such as a semiconductor pressure sensor for detecting the internal pressure of 7
0 is provided.

Next, the configuration of the evaporation gas purge system 21 will be described. A canister 23 is connected to the fuel tank 17 via a communication pipe 22. This canister 2
3, an adsorbent 24 such as activated carbon for adsorbing evaporative gas.
Is housed. At the bottom of the canister 23, an atmosphere communication pipe 25 communicating with the atmosphere is provided, and a canister closing valve 26 is attached to the atmosphere communication pipe 25.

The canister closing valve 26 is constituted by an electromagnetic valve, and when the power to the solenoid coil 27 is turned off as shown in FIG. 2, the valve body 28 is urged by a spring 29 to an open position. The atmosphere communication pipe 25 of the canister 23 is kept open to the atmosphere. When a predetermined voltage (for example, 6 V or more) is applied to the solenoid coil 27, the valve body 28 is moved to the closing position against the urging force of the spring 29, and the atmosphere communication pipe 25 is closed by the valve body 28 on the way. It will be in the state that was done.

On the other hand, as shown in FIG.
Purge passages 30 a and 30 b for purging (discharging) the evaporative gas adsorbed by the adsorbent 24 into the intake pipe 12 are provided between the purge passage 3 and the suction pipe 3.
Purge control valve 3 for adjusting the purge flow rate between 0a and 30b
1 is provided. As shown in FIG. 3, the purge control valve 31 has a port 32 connected to the purge passage 30a on the canister 23 side and a purge passage 30 on the intake pipe 12 side.
b, and both ports 32, 3
A valve body 35 that opens and closes the passage 34 between the three ports, a spring 36 that urges the valve body 35 in the valve closing direction, and moves the valve body 35 in the valve opening direction against the urging force of the spring 36. The solenoid valve is provided with a solenoid coil 37 to be operated.

A voltage is applied to the solenoid coil 37 of the purge control valve 31 in the form of a pulse signal. By changing the ratio of the pulse width to the cycle of the pulse signal (duty ratio), the opening / closing cycle of the valve element 35 is controlled. The purge flow rate of the evaporative gas from the canister 23 to the intake pipe 12 is controlled by changing the ratio of the valve opening time of the valve body 35. FIG. 4 shows a change characteristic between the drive duty of the purge control valve 31 and the purge flow rate.

Also, as shown in FIG.
Is provided with a lid 38 with a relief valve. When the internal pressure of the fuel tank exceeds -40 mmHg to 150 mmHg (relief pressure), the relief valve of the lid 38 is opened to release pressure. It has become. Therefore, the section from the fuel tank 17 to the canister 23 is always suppressed to a pressure fluctuation within the relief pressure range.

Next, the configuration of the control system will be described with reference to FIG. The control circuit 39 interconnects a CPU 40, a ROM 41 storing various control programs and data described later, a RAM 42 for temporarily storing input data and operation data, and an input / output circuit 43 via a common bus 44. It is configured. The input / output circuit 43 includes a throttle sensor 45, an idle switch 46, a vehicle speed sensor 4
7, various operating state detecting means such as an atmospheric pressure sensor 48, an intake pipe pressure sensor 49, a cooling water temperature sensor 50, an intake air temperature sensor 51, etc. are connected, and input from the operating state detecting means via the input / output circuit 43. Signal and ROM 41 or R
Based on the programs and data in the AM 42, the air-fuel ratio feedback control, the fuel injection control, the ignition control, the evaporative gas purge control, the abnormality diagnosis of the evaporative gas purge system 21 and the like are executed, and the fuel injection valve 16, the ignition plug 52, the canister closed A drive signal is output to the valve 26, the purge control valve 31, and the like via the input / output circuit 43, and a warning lamp 53 is turned on to notify the driver when the evaporative gas purge system 21 is abnormal. Hereinafter, various controls performed by the control circuit 39 will be described.

[Air-fuel ratio feedback control] The air-fuel ratio feedback (F / B) control routine is executed by interrupt processing every 4 msec, for example, according to the flowchart of FIG. When the process of this routine is started, first, in step 101, it is determined whether a feedback execution condition is satisfied. Here, the feedback execution conditions include (1) that the engine is not started,
(2) No fuel cut, (3) Cooling water temperature THW
≧ 40 ° C., (4) Fuel injection amount TAU> TAU
min (where TAUmin is the fuel injection valve 16
(5) The oxygen sensor (not shown) for detecting the oxygen concentration of the exhaust gas may be in an active state, etc., and when all of these conditions (1) to (5) are satisfied, If the feedback execution condition is satisfied and at least one condition is not satisfied, the feedback execution condition is not satisfied. If the feedback execution condition is not satisfied, the routine proceeds to step 102, where the air-fuel ratio correction coefficient FAF (corresponding to the air-fuel ratio feedback correction amount) is set to "1.0", and this routine ends.

On the other hand, if the feedback execution condition is satisfied, the routine proceeds to step 103, where the output of the oxygen sensor is compared with a predetermined determination level, and the air-fuel ratio is delayed by predetermined times H and I (msec), respectively. Flag XOXR
Operate. Specifically, XOXR = 0 after H (msec) after the oxygen sensor output is inverted from rich to lean.
(Meaning lean), and XOXR after I (msec) after the oxygen sensor output is inverted from lean to rich
= 1 (meaning rich).

In the next step 104, the value of the air-fuel ratio correction coefficient FAF is manipulated as follows based on the air-fuel ratio flag XOXR. That is, the air-fuel ratio flag XOXR changes from “0” to →
When it changes from “1” or “1” to “0”, the value of the air-fuel ratio correction coefficient FAF is skipped by a predetermined amount, and the air-fuel ratio XO
When XR is maintained at "1" or "0", the integral control of the air-fuel ratio correction coefficient FAF is performed. Thereafter, in step 105, upper and lower limits of the value of the air-fuel ratio correction coefficient FAF are checked (guard processing), and in step 106, smoothing is performed every skip or every predetermined time based on the air-fuel ratio correction coefficient FAF (average). ) Process to calculate an average value FAFAV of the air-fuel ratio correction coefficient, and terminates the present routine.

[Purge Rate Control] The purge rate control is executed by interrupt processing every 32 msec, for example, according to the flowchart of FIG. When the process is started, first, at step 201, it is determined whether or not the cooling water temperature THW is 80 ° C. or higher, and at step 202, it is determined whether or not the air-fuel ratio is being fed back. At this time, if the engine is warmed up (THW ≧ 80 ° C.) and the normal air-fuel ratio feedback is executed (when the condition of step 101 in FIG. 4 is satisfied), both steps 201 and 202 are “Yes”.
And the process proceeds to step 205.

At step 205, "1" is set to the purge execution flag XPRG, and then at steps 206-2.
At 09, the final purge rate PGR (the ratio of the purge flow rate to the intake air amount) is calculated as follows. First, in step 206, based on the intake pipe pressure PM and the engine speed NE, the fully open purge rate PGRM is obtained from the two-dimensional map of FIG.
Read X. In the next step 207, the target purge rate PGRO is calculated by dividing the target TAU correction amount KTPRG by the evaporative gas concentration average value FGPGAV (PGRO = K
TPRG / FGPGAV).

Here, the target TAU correction amount KTPRG corresponds to the maximum correction amount when the fuel injection amount TAU is reduced and corrected. In addition, the evaporative gas concentration average value FGPG
AV corresponds to the amount of evaporative gas adsorbed in the canister 23, is estimated by a process described later, and is written to the RAM 42 while being updated as needed. Therefore, the target purge rate PGRO corresponds to how much evaporative gas should be replenished by purging when it is assumed that the fuel injection amount is reduced to the target TAU correction amount KTPRG. In this case, if the operation state is the same, the target purge rate P
GRO becomes smaller as the average vapor gas concentration value FGPGAV becomes larger. In the present embodiment, the target TAU correction amount KTPRG is set to, for example, 30%.

After calculating the target purge rate PGRO, in step 208, the purge rate gradually changing value PGRD is read. Here, the purge rate gradual change value PGRD is a control value provided in order to avoid a situation in which if the purge rate is suddenly greatly changed, the correction cannot catch up and the optimum air-fuel ratio cannot be maintained. The method of setting the purge rate gradual change value PGRD will be described in the purge rate gradual change control described later.

Thus, the full open purge rate PGRMX,
When the target purge rate PGRO and the purge rate gradual change value PGRD are obtained, the process proceeds to step 209, and the minimum value among these is determined as the final purge rate PGR. Purge control is performed at the final purge rate PGR. In this case, the final purge rate PGR is normally controlled by the purge rate gradual change value PGRD. If the purge rate gradual change value PGRD continues to increase, the final purge rate PGR becomes the upper limit guard by the full open purge rate PGRMX or the target purge rate PGRO. Will be done.

On the other hand, in step 201, THW <80
When the temperature is ° C, or when the air-fuel ratio feedback is not being performed in step 202, the process proceeds to step 210, where the purge execution flag XPRF is cleared to “0”, and in the subsequent step 211, the final purge rate PGR is reset to “0”. Then, this routine ends. This final purge rate PG
When R is “0”, it means that the evaporative gas purge is not performed. That is, when the cooling water temperature is low (THW <80 ° C.), such as before the engine 11 is warmed up, the fuel increase other than the purge is performed by the water temperature correction, and the purge rate control is not executed.

[Purge rate gradual change control] The purge rate gradual change control is performed, for example, for 32 msec according to the flowchart of FIG.
It is executed by interrupt processing for each. When the process is started, first, in step 301, a purge execution flag XPRG
Is determined to be “1”, and if XPRG = 0,
That is, if the purge rate control is not executed, the process proceeds to step 306, where the purge rate gradual change value PGRD is set to “0”, and this routine ends.

On the other hand, if XPRG = 1, the routine proceeds to step 302, where the deviation amount | 1-F of the air-fuel ratio correction coefficient FAF is determined.
AFAV | is detected. At this time, | 1-FAFAV |
If ≤5%, the routine proceeds to step 303, where the value obtained by adding "0.1%" to the previous final purge rate PFR (i-1) is set as the current purge rate gradual change value PFRD. Also, 5% <| 1-F
If AFAV | ≤10%, the routine proceeds to step 304, where the last final purge rate PGR (i-1) is set to the current purge rate gradual change value PGRD. If | 1-FAFAV |> 10%, the routine proceeds to step 305, where a value obtained by subtracting "0.1%" from the last final purge rate PGR (i-1) is set as the current purge rate gradually changing value PGRD. . If the purge rate is largely changed, the correction cannot catch up and the optimum air-fuel ratio cannot be maintained, so that such a problem is avoided by the purge rate gradual change value PGRD as described above.

[Detection of Evaporation Gas Concentration] Evaporation gas concentration detection is performed, for example, for 4 msec according to the flowchart of FIG.
It is executed by interrupt processing for each. When the process is started, first, at step 401, it is determined whether or not the key switch is turned on. If the key switch is turned on, each data is initialized in steps 412 to 414, the evaporative gas concentration FGPG = 1.0, and the evaporative gas concentration average value FGPG.
AV = 1.0, initial density detection end flag XNFGPG =
Reset to zero. Here, the evaporation gas concentration FGPG =
1.0, average evapogas concentration value FGPGAV = 1.0
Means that the evaporative gas concentration is "0" (in other words, no evaporative gas is adsorbed on the canister 23). When the engine is started, the amount of adsorption is assumed to be “0” by initialization. Initial concentration detection end flag XN
FGPG = 0 means that the evaporative gas concentration has not been detected yet after the engine is started.

After the key switch is turned on, the routine proceeds to step 402, where it is determined whether or not the purge execution flag XPRG is "1", that is, whether or not purge control has been started. Here, if XPRG = 0 (before the start of the purge control), this routine is terminated as it is. On the other hand, XPRG
If = 1 (after the start of the purge control), step 403
To determine whether the vehicle is accelerating or decelerating. Here, the determination as to whether the vehicle is accelerating or decelerating is made based on the detection results of the turning off of the idle switch 46, the change in the valve opening of the throttle valve 14, the change in the intake pipe pressure, the change in the vehicle speed, and the like.
Then, when it is determined that the vehicle is accelerating / decelerating, the routine ends as it is. That is, during acceleration / deceleration (transient state of engine operation), the detection of the evaporative gas concentration is prohibited, and the erroneous detection is prevented.

If it is determined in step 403 that acceleration / deceleration is not being performed, the flow advances to step 404 to determine whether the initial concentration detection end flag XNFPG is "1", that is, the first detection of the evaporative gas concentration is completed. Is determined. If XNFGPG = 1 (after the initial concentration detection), the process proceeds to step 405. If XNFPG = 0 (before the initial concentration detection), the process skips step 405 and proceeds to step 406.

At first, since the evaporative gas concentration detection has not been completed (XNFGPG = 0), the process proceeds from step 404 to step 406, where the smoothed value FAF of the air-fuel ratio correction coefficient is obtained.
AV is a predetermined value ω (for example, 2%) with respect to a reference value (= 1)
It is determined whether or not there is the above deviation. That is, if the amount of deviation of the air-fuel ratio due to the evaporative gas purge is too small, the evaporative gas concentration cannot be correctly detected. Therefore, if the deviation amount of the air-fuel ratio is small (| 1−FAFAV | ≦ ω), this routine is terminated as it is. If the deviation of the air-fuel ratio is large (| 1-FAFAV |> ω), the routine proceeds to step 407, where the evaporation gas concentration FGPG is detected by the following equation (1).

FGPG = FGPG (i−1) + (FAFAV−1) / PGR (1) In the above equation, (FAFAV−1) corresponds to the air-fuel ratio feedback correction amount deviation, and PGR is calculated as shown in FIG. Step 2
09 is the final purge rate calculated.

As described above, the initial value of the evaporative gas concentration FGPG is "1", and according to the above equation, the evaporative gas concentration FGPG depends on whether the air-fuel ratio is lean or lean.
Is updated gradually. In this case, the value of the evaporative gas concentration FGPG is reduced based on "1" as the actual evaporative gas concentration is higher (the more the canister 23 is adsorbed). Further, the value of the evaporation gas concentration FGPG is increased in accordance with the actual decrease in the evaporation gas concentration (the purge amount of the canister 23). Specifically, if the air-fuel ratio is rich (FAFAV-1 <0), the evaporation gas concentration FGPG
Becomes smaller by a value obtained by dividing “FAFAV-1” by the final purge rate PGR. If the air-fuel ratio is lean (FAFAV-1> 0), the value of the evaporation gas concentration FGPG is increased by a value obtained by dividing "FAFAV-1" by the final purge rate PGR.

Thereafter, the process proceeds to step 408, where it is determined whether or not the initial density detection end flag XNFGPG is "1" which means the end of the initial density detection. Where XNFG
If PG = 0 (before the initial concentration detection), step 409
To determine whether the state in which the change between the previous detection value and the current detection value of the evaporation gas concentration FGPG is equal to or less than a predetermined value (for example, 3%) has been continued, for example, three times or more.
It is determined whether the GPG has stabilized. Evaporative gas concentration F
When the GPG is stabilized, the process proceeds to the next step 410, where "1" is set to the initial concentration detection end flag XNFGPG, and then the process proceeds to step 411.

On the other hand, in step 408, XNFGP
In the case of G = 1 or in step 409, the evaporation gas concentration F
If it is determined that the GPG is not stable, step 4
11 to execute a predetermined smoothing operation (for example, 1/64 smoothing operation) in order to average the current evaporative gas concentration FGPG, and evaporative gas concentration average value FGPGA.
Find V.

When the initial density detection is completed in this way (when XNFGPG = 1 is set), step 40 is executed.
4 is always determined as “Yes”, and the routine proceeds to step 405, where it is determined whether or not the final purge rate PGR exceeds a predetermined value β (for example, 0%). Then, only when PGR> β, the evaporative gas concentration detection after step 406 is executed. That is, even if the purge execution flag XPRG is set, the final purge rate PGR becomes “0”, and the evaporative purge may not be actually performed. for that reason,
Except during the initial concentration detection, the evaporative gas concentration is not detected when the final purge rate PGR = 0.

When the final purge rate PGR is small, that is, when the purge control valve 31 is controlled on the low flow rate side, the accuracy of the opening degree control is relatively low, and the reliability of evaporative gas concentration detection is low. Therefore, the predetermined value β in step 405 is set in the low opening range of the purge control valve 31 (for example, 0% <β <2
%), Except at the time of the first detection, the evaporation gas concentration detection may be performed only when accurate detection conditions are met.

[Fuel Injection Amount Control] The fuel injection amount control is executed by interruption processing at intervals of, for example, 4 msec in accordance with the flowchart of FIG. When the process is started, first, in step 501, it is determined whether or not the fuel cut flag XFC is “0” meaning that fuel cut is not executed.
If C = 1 (fuel cut execution), the routine proceeds to step 506, where the fuel injection amount TAU is set to "0", and this routine ends. Thereby, a fuel cut is performed.

On the other hand, if XFC = 0 (fuel cut is not executed), the routine proceeds to step 502, where the engine speed NE and the load (for example, the intake pipe pressure PM) are changed based on the data stored as a map in the ROM 41. The corresponding basic injection amount TP is calculated. Then, in the next step 503, various corrections regarding the operating state of the engine 11 (cooling water temperature correction, post-start correction, intake air temperature correction, etc.) are performed. Thereafter, in step 504, a purge correction coefficient FPG is calculated by the following equation (2) in accordance with the evaporative gas concentration average value FGPGAV calculated in the routine of FIG. 9 and the final purge rate PGR calculated in the routine of FIG.

FPG = (FGPGAV-1) · PGR (2) The purge correction coefficient FPG means a fuel amount to be replenished by performing a purge under the conditions determined by the purge rate control process. The corresponding amount of the coefficient is corrected to decrease from the basic injection amount TP.

Thereafter, at step 505, the air-fuel ratio correction coefficient FAF, the purge correction coefficient FPG and the air-fuel ratio learning value KG
j, a correction coefficient Km is obtained by the following equation (3), and the correction coefficient Km is multiplied by the basic injection amount TP to obtain a fuel injection amount TA.
Reflect on U. Km = 1 + (FAF-1) + (KGj-1) + FPG (3)

The air-fuel ratio learning value KGj is equal to the backup R
This is backup data stored and held in an AM (not shown), and is a coefficient set for each engine operation area. Then, the CPU 40 executes fuel injection by the fuel injection valve 16 based on the fuel injection amount TAU at a predetermined fuel injection timing.

[Control of Purge Control Valve] Purge control valve 31
Is controlled, for example, in accordance with the flowchart of FIG.
It is executed by interrupt processing every 0 msec. When the process is started, first, in step 601, it is determined whether or not the purge execution flag XPRG is “1” meaning that purge is executed. If XPRG = 0 (purge is not executed), the process proceeds to step 602. , The control value Duty for driving the purge control valve 31 is set to “0”. Also, XPRG = 1
If (purge is executed), the process proceeds to step 603, and the control value Duty is calculated by the following equation (4) based on the final purge rate PGR and the full-open purge rate PGRMX corresponding to the operation state at that time. Duty = (PGR / PGRMX) · (100−Pv) · Ppa + Pv (4)

In this equation, the drive cycle of the purge control valve 31 is set to 100 msec. Pv is a voltage correction value for the fluctuation of the battery voltage (equivalent amount of time for driving cycle correction), and Ppa is an atmospheric pressure correction value for the fluctuation of the atmospheric pressure. The control value Du calculated by the above equation (4)
The duty ratio of the drive pulse signal of the purge control valve 31 is set based on ty.

[Abnormality Diagnosis] Evaporative gas purge system 2
When the key switch (not shown) is turned on, the abnormality diagnosis 1 is repeatedly executed at predetermined time intervals (for example, at every 256 msec) according to the flowcharts of FIGS. This abnormality diagnosis routine plays a role as abnormality diagnosis means referred to in the claims.

When the processing of this routine is started, first, at step 701 in FIG. 12, it is determined whether or not the execution condition is satisfied. Here, the execution condition is satisfied when the engine operation state is stable. Specifically, the intake air amount =
5.0 to 40 g / s, intake air temperature = -10 to 70 ° C, starting cooling water temperature = -7.5 to 35 ° C, starting intake air temperature = -10
70 ° C, 700 seconds or more after starting, battery voltage 10V
As described above, the execution condition is that the air-fuel ratio feedback is being executed. When all of these conditions are satisfied, the execution condition is satisfied, and the process proceeds to step 702. When the execution condition is not satisfied, the abnormality diagnosis is prohibited, and FIG. Step 740 of
, The canister closing valve 26 is fully opened, and in a subsequent step 741, the purge control valve 31 is brought into a normal control state, and then the process proceeds to step 731 in which the first to fourth flags F
1, F2, F3 and F4 are reset to "0", and this routine ends.

On the other hand, if the execution condition is satisfied,
The process proceeds from step 701 in FIG. 12 to step 702 to determine whether the prohibition condition is not satisfied. Here, the prohibition conditions include, when a misfire occurs, when the operating state detecting means fails (for example, when the fuel level gauge fails, when the vehicle speed sensor 47 fails,
At the time of fuel tank internal pressure sensor failure, air flow sensor failure, intake pipe pressure sensor 50 failure, rotation sensor failure, throttle sensor 45 failure, atmospheric pressure sensor 48
, Oxygen sensor failure, intake air temperature sensor 51 failure, cooling water temperature sensor 50 failure), fuel supply system failure, ignition system failure, canister closing valve 26 failure, oxygen sensor heater failure The prohibition condition is satisfied if any one of the conditions is satisfied, and the prohibition condition is not satisfied if none of the conditions is satisfied. If the prohibition condition is satisfied, as in the case where the execution condition is not satisfied, the abnormality diagnosis is prohibited, the canister closing valve 26 is fully opened (step 740), and the purge control valve 31 is set to the normal control state (step 741). ), The first to fourth flags F1, F
2, F3 and F4 are reset to "0" (step 73)
1), end this routine.

On the other hand, if the prohibition condition is not satisfied, the routine proceeds to step 703, in which the evaporative gas concentration change amount ΔFGPG is equal to or smaller than the judgment value KFLGA and the evaporative gas concentration FGPG
Is smaller than or equal to the determination value KFLGB, it is determined whether the amount of evaporated gas (the amount of evaporated gas adsorbed in the canister 23) is small. Here, the evaporation gas concentration change amount ΔFGPG is measured during the execution of the purge before performing the abnormality diagnosis. Immediately after the purge is started, the evaporative gas generation state is unstable for a while, and the evaporative gas concentration fluctuates. For this reason, as shown in FIG. 14, after a predetermined time T1 required for the evaporative gas concentration to stabilize after the start of the purge, The measurement of the evaporative gas concentration is started, and the change amount ΔFGPG of the evaporative gas concentration changed during the predetermined time T2 is measured. In other words, the evaporation gas concentration FGPG (T
1), and after that, an evaporative gas concentration FGPG (T2) after a lapse of a predetermined time T2 is detected.
The difference between PG (T1) and FGPG (T2) is defined as a change amount ΔFGPG of the evaporative gas concentration. Alternatively, FGPG (T1) and FGPG (T1
The value obtained by dividing the difference in 2) by FGPG (T1) or FGPG (T2) (or the reciprocal thereof) is used as the evaporative gas concentration change amount ΔFGPG.
It is good.

The determination values KFLGA and KFLGB used in the determination in step 703 may be predetermined constant values. In the present embodiment, the determination values KFLGA and KFLGB are obtained by using the map (a) or (b) shown in FIG. Judgment values KFLGA, KF from the map according to the current cooling water temperature or the accumulated execution time of purge
Set LGB. This function corresponds to a set value setting unit described in the claims.

The determination values KFLGA, KFLGB may be set based on the elapsed time after starting, or the cooling water temperature,
The determination values KFLGA and KFLGB may be set using two or more data from the accumulated purge execution time and the elapsed time after the start. When the determination values KFLGA, KFLGB are set according to the cooling water temperature, the determination values KFLGA, KFLGB set according to the cooling water temperature at the time of starting are set.
May be used without change even after the start is completed. The processing of step 703 serves as an execution condition determining means referred to in the claims.

If the determination in step 703 is "No", that is, if it is estimated that the amount of evaporative gas generated is large, the abnormality diagnosis is prohibited, the canister closing valve 26 is fully opened (step 740), and the purge control is performed. The valve 31 is set to the normal control state (step 741), and the first to fourth flags F
1, F2, F3 and F4 are reset to "0" (step 731), and this routine ends.

On the other hand, the determination in step 703 is “Yes”
In other words, if the amount of evaporative gas generation is estimated to be small, the process proceeds to step 704, where it is determined whether the fourth flag F4 is "1". If F4 = 0, the process proceeds to step 705. , The atmospheric pressure Pa1 is read, and the following step 7
At 06, the fourth flag F4 is set to "1" and the routine proceeds to step 707.

In step 704, if F4 = 1, the first reading of the atmospheric pressure Pa1 has already been completed, so the flow jumps to step 707 to read the second atmospheric pressure Pa2. At the next step 708, the atmospheric pressure change Δ
After calculating Pa (= Pa2−Pa1), the routine proceeds to step 709, where the absolute value of the atmospheric pressure change ΔPa becomes a predetermined value (for example, 3 m).
mHg) or more. If | ΔPa
If | ≧ 3 mmHg, the abnormality diagnosis is prohibited, the canister closing valve 26 is fully opened (step 740), the purge control valve 31 is set to the normal control state (step 741), and the first to fourth flags F1 are set. , F2, F3, and F4 are reset to "0" (step 731), and this routine ends.

On the other hand, if | ΔPa | <3 mmHg, the process proceeds to steps 710 to 712, and branches to various steps while judging to what stage the current process has progressed. The processing is performed in four stages of first to fourth stages, and the processing stage can be determined from each set state of the first to third flags F1 to F3. All flags F1 to F3
Is set to "0", that is, Steps 710-710
The first stage is when all 712 are “No”, and the process proceeds to step 713.

In the first stage, first, in step 713, the purge control valve 31 is fully closed, and then, in step 714, the canister closing valve 26 is fully closed to seal the purge path from the fuel tank 17 to the intake pipe 12. State. That is, as shown in FIG. 16, first, when the canister closing valve 26 is in the open state, the purge control valve 31 is fully closed at time T1, so that the evaporative gas purge system from the fuel tank 17 to the purge control valve 31 is opened to the atmosphere. At the same pressure as the atmospheric pressure via the communication pipe 25, the canister closing valve 2 is slightly delayed at time T2.
By completely closing 6, an evaporative gas purge system maintained at atmospheric pressure is formed.

Then, in the next step 715, the fuel tank internal pressure P1a at time T2 in FIG.
After reset start, the process proceeds to step 716,
It is determined whether or not the count value of the timer T has reached 10 seconds or more. If 10 seconds have not elapsed, the routine proceeds to step 717, where the first flag F1 is set to "1", and this routine ends.

Thereafter, the process of the second stage is performed. In this second stage, "Yes" is determined in step 710, and steps 701 to 710 → step 716
→ Repeat the process. During this time, the detection value of the pressure sensor 20 is between time T2 and time T3 in FIG.
0 m according to the amount of evaporative gas generated in the fuel tank 17
rise from mHg.

Thereafter, when 10 seconds have elapsed from time T2 (the point of time when P1a is detected), the process proceeds to step 718 in FIG.
The input signal from the pressure sensor 20 is read, the fuel tank internal pressure P1b at this time is stored, and the subsequent step 719
After calculating the pressure change amount ΔP1 for 10 seconds, in step 720, the first flag F1 is reset. Thus, the processing in the second stage is completed, and the process proceeds to the third stage.

In the third stage, first, step 721
Then, the purge control valve 31 is switched from the fully closed state to the fully open state, and the timer T is reset and started. Here, when the purge control valve 31 is fully opened, the intake pipe negative pressure starts to be introduced into the evaporative gas purge system under the atmospheric pressure introduced before that (time T3 in FIG. 16). Therefore, if there is no abnormality due to pressure leak or the like in the evaporative gas purge system, the pressure sensor 2
The detected value of 0 starts to fall.

In the next step 722, the fuel tank internal pressure PT is reduced based on the input signal from the pressure sensor 20.
It is determined whether the pressure has become 20 mmHg or less, and PT> −2.
If it is 0 mmHg, the process proceeds to step 732, and it is determined whether 10 seconds have elapsed after the purge control valve 31 has been fully opened.
If 10 seconds have not elapsed, the process proceeds to step 737, where the second flag F2 is set to "1". After this, step 7
At 38, it is determined whether or not the air-fuel ratio correction coefficient FAF is within ± 20%. If the FAF is within ± 20%, the routine proceeds to step 739, where the pressure difference between the atmospheric pressure Pa and the intake pipe pressure PM is determined. Is greater than or equal to a predetermined value (for example, 150 mmHg).

When one of these steps 738 and 739 is determined to be “No”, that is, when the air-fuel ratio correction coefficient F
When the AF exceeds ± 20% or when the pressure difference from the intake pipe pressure PM is less than a predetermined value (for example, 150 mmHg), the abnormality diagnosis is prohibited, the canister closing valve 26 is fully opened (step 740), and the purge is performed. The control valve 31 is set to the normal control state (step 741), and the first to fourth flags F
1, F2, F3 and F4 are reset to "0" (step 731), and this routine ends. Step 7
If the determinations of 38 and 739 are both “Yes”, the present routine is terminated as it is.

In this case, the second flag F2 is set to “1” in step 737, so that the next time this routine is executed, “No” is determined in step 710, and “Yes” is determined in step 711. , And the process is repeated in steps 701 to 711 → step 722 →. This state corresponds to step 722 or step 73.
The process ends when 2 becomes “Yes”. If "Yes" is determined earlier in step 732, it means that there is a blockage somewhere in the purge path from the fuel tank 17 to the intake pipe 12, and in step 733, the purge system clogging flag Fclose Is set to "1", and in the following step 734,
The warning lamp 53 is turned on.

On the other hand, in step 722, “Ye
s ”, the process proceeds to step 723 and the second
After resetting the purge control valve 31 in step 724, the purge control valve 31 is fully closed again.
Then, the input signal from the pressure sensor 20 is read, the fuel tank internal pressure P2a immediately after the evaporative gas purge system is closed in the negative pressure state is stored, and the timer T is reset and started. Thereby, the process moves from the third stage to the fourth stage.

By performing the processing of the above steps 723 to 725, as shown in FIG. 16, at time T4, the inside of the closed purge path is adjusted to a negative pressure of -20 mmHg. Thereafter, the detection value of the pressure sensor 20 is
From time T4 to time T5, the pressure increases from -20 mmHg according to the amount of evaporative gas generated in the fuel tank 17.

Then, in the next step 726, it is determined whether or not 10 seconds have elapsed after the reading of P2a. Before 10 seconds have elapsed, the process proceeds to step 735, and the third flag F3 is set to "1". Then, this routine ends. This allows
At the time of execution of this routine from the next time, steps 710 and 7
11, “No” is determined, and “Yes” is determined in step 712, and steps 701 to 712 → step 7
The process is repeated in the order of 26 →...

Thereafter, when 10 seconds have elapsed from the reading of P2a, the routine proceeds to step 728, where the input signal from the pressure sensor 20 is read, and the fuel tank internal pressure P at time T6 is read.
2b, and the pressure change amount ΔP2 (= P
2b-P2a) is calculated. Thereafter, in step 730, it is determined whether or not there is a leak based on the leak determination condition shown by the following equation (5). ΔP2> α · ΔP1 · BA + β (5)

Here, α is a coefficient for correcting the difference in the amount of fuel evaporation due to the difference between the atmospheric pressure and the negative pressure, and β is a coefficient for correcting the detection accuracy of the pressure sensor 20, the pressure leak of the canister closing valve 26, and the like. BA is a correction coefficient for correcting the pressure change amount ΔP1 under the atmospheric pressure in accordance with the evaporative gas concentration. For example, BA is set according to the evaporative gas concentration from the map shown in FIG. This function corresponds to the detection value correcting means in the claims. In the above equation (5), the pressure change amount ΔP1 from the atmospheric pressure is corrected according to the evaporative gas concentration. However, the pressure change amount ΔP2 from the negative pressure may be corrected according to the evaporative gas concentration. good.

In place of the above equation (5), the following equation (6)
It may be determined whether or not there is a leak based on the leak determination condition shown by the equation. ΔP2> α · ΔP1 + β + BB (6) where BB is a correction coefficient for correcting the pressure change ΔP1 from the atmospheric pressure according to the evaporative gas concentration. For example, from the map shown in FIG. It is set according to the density.

In the map of FIG. 17, the correction coefficients BA and BB are set according to the evaporative gas concentration.
The correction coefficients BA and BB may be set according to the amount of change in the evaporative gas concentration, or the correction coefficients BA and B may be set based on both the evaporative gas concentration and the amount of change in the evaporative gas concentration.
B may be set. Further, a correction coefficient BA,
A correction based on the intake air temperature may be added to BB.

If it is determined in step 730 that the above equation (5) or (6) is satisfied, it is determined that "there is a leak". That is, if there is a leak cause in the evaporative gas purge system from the fuel tank 17 to the purge control valve 31, the outflow from the evaporative gas purge system to the atmosphere occurs under positive pressure, while the evaporative gas purge system flows from the atmosphere to the evaporative gas purge system under negative pressure. Air inflow occurs. Therefore, "(pressure change amount from atmospheric pressure ΔP1) = (amount of evaporative gas generated from fuel tank 17)-(amount of outflow from the evaporative gas purge system to the atmosphere)"
"(The amount of change in pressure from the negative pressure ΔP2) = (the amount of evaporative gas generated from the fuel tank 17) + (the amount of inflow from the atmosphere into the evaporative gas purge system)" is larger. From this relationship, the leak determination condition of the above equation (5) or (6) is derived.

If the leak determination condition of the above formula (5) or (6) is satisfied, that is, if it is determined that “there is a leak” in step 730, the purge path from the fuel tank 17 to the intake pipe 12 is changed. This means that there is a part causing a leak somewhere. In step 736, the purge path leak flag Fleak is set to “1”, and the subsequent step 73
At 4, the warning lamp 53 is turned on. On the other hand, step 73
If “0” is determined as “NO”, that is, if no leak has occurred, the process proceeds to step 731 and the first to fourth steps are performed.
Are forcibly reset, and this routine is terminated.

The modes of various abnormalities that can be detected by the above-described abnormality diagnosing process are as follows.

Case: Communication pipe 22 or purge passage 30
Damage and dropout at a Atmospheric pressure flows into the atmosphere under negative pressure due to damage and dropout under negative pressure, and outflow into the atmosphere under positive pressure. Therefore, it is determined that there is a leak at step 730, and an abnormality can be reported. .

Case: Communication pipe 22 or purge passage 30
Bending, crushing, etc. in a. The pressure does not decrease even if a negative pressure is introduced, or the pressure decreases slowly, so that “No” is determined in step 722 and “Yes” in step 732 to notify the abnormality. it can.

Case: The purge control valve 31 cannot be opened. Negative pressure cannot be introduced, and similarly to the case, "No" in step 722 and "Yes" in step 732, and an abnormality can be reported. When the purge control valve 31 cannot be opened, the adsorbent 2 in the canister 23 is opened.
4 cannot be introduced into the intake pipe 12, and thereafter exceeds the evaporation gas adsorption capacity of the adsorbent 24.
Evaporative gas is released from the atmosphere communication pipe 25.

Case: Dropping of the purge passage 30b Negative pressure cannot be introduced from the intake pipe 12, and as in the case, “No” in step 722 and “Yes” in step 732 to notify an abnormality. Can be. Since the case is not a blockage but a drop-off, the type of abnormality is wrong, but the purpose of abnormality diagnosis can be sufficiently achieved if the presence of abnormality can be accurately determined.

Case: Bending, collapsing, etc. in the purge passage 30b This is exactly the same as in the case, and “No” in step 722 and step 732 based on the state of introduction of the negative pressure.
To "Yes", and an abnormality can be notified. The state of this case is the same as that of the case.
There is a possibility that fuel gas is released from the fuel cell 5, which is an abnormality that needs to be detected.

Case: Atmospheric communication pipe 2 of canister 23
Blockage 5 This anomaly does not immediately cause a large pressure rise, such as a rubber hose collapse or bend. In the case where the purge passage 30 is crushed or the like, the evaporative gas cannot be purged even if the purge control valve 31 is opened. However, even if the atmosphere communication pipe 25 of the canister 23 is closed, when the purge control valve 31 is opened. This is because the evaporative gas is purged as such. Therefore, the abnormality diagnosis routine described above does not detect an abnormality in which the atmosphere communication pipe 25 of the canister 23 remains closed, but there is no major problem. If necessary, in step 728 of the abnormality diagnosis routine described above, the canister closing valve 26 is opened immediately after detecting the fuel tank internal pressure P2b, and if the pressure does not quickly return to the vicinity of the atmospheric pressure, the blocking abnormality of the atmosphere communication pipe 25 is detected. What is necessary is just to determine that there is.

Case: A state in which the purge control valve 31 cannot be closed.
It will be introduced into the inside, but it does not cause secondary release of evaporative gas from the atmosphere communication pipe 25 as in the case of being unable to open, and it is not abnormal from the viewpoint of preventing evaporation of evaporative gas. good. Therefore, in the above-described abnormality diagnosis routine, a method for specifically detecting this abnormality is not provided. If necessary, if ΔP1 calculated in step 719 becomes equal to or less than the predetermined negative pressure, it may be determined that the purge control valve 31 cannot be closed.

Case: A state in which the purge passage 30b is damaged such as a crack. The purge passage 30b is a portion through which the evaporative gas passes only when the purge control valve 31 is opened. Only acts in the same way as the atmosphere communication pipe 25 of the canister 23, and it is needless to say that there is no particular problem from the viewpoint of preventing evaporation of evaporation gas. Therefore, although the above-described abnormality diagnosis routine cannot detect this, there is no problem.

In the embodiment described above, step 70
3, the evaporative gas concentration change amount is equal to or less than the determination value KFLGA,
In addition, it is determined whether or not the amount of evaporative gas generation is small based on whether or not the evaporative gas concentration is equal to or less than the determination value KFLGB, and the execution / stop of the abnormality diagnosis is determined. When the abnormality diagnosis of the evaporative gas purge system is stopped, the drivability and the exhaust emission can be prevented from deteriorating. At other times, the abnormality diagnosis is performed and the abnormality of the evaporative gas purge system is detected at an early stage. Can be.

It should be noted that the determination in step 703 may be changed to only “evaporative gas concentration change amount ≦ KFLGA” and the execution / stop of the abnormality diagnosis may be determined based on whether or not the evaporative gas concentration change amount ≦ KFLGA. When the amount of evaporative gas generated increases, the amount of change in evaporative gas concentration increases. Therefore, it is possible to estimate the amount of evaporative gas generated from the amount of change in evaporative gas concentration and determine whether to execute / stop abnormality diagnosis.

The determination in step 703 may be changed to “evaporative gas concentration change amount ≦ KFLGC”, and the execution / stop of the abnormality diagnosis may be determined based on whether or not the evaporative gas concentration change amount ≦ KFLGC. In this case, the determination value KFLGC is set according to the cooling water temperature or the cumulative execution time of the purge according to the map (a) or (b) of FIG. Alternatively, the determination value KFLGC may be set based on the elapsed time after the start, or the determination value KFLC may be set using two or more data from the cooling water temperature, the accumulated execution time of the purge, and the elapsed time after the start.
FLGC may be set.

Further, the determination value KFLGC may be corrected by the following equation using a correction value KFLGK based on the intake air temperature. KFLGC = KFLGC-KFLGK The correction value KFLGK based on the intake air temperature is set according to the intake air temperature by using the map (c) in FIG.

In the abnormality diagnosis routine shown in FIGS. 12 and 13, the pressure change is corrected in step 730 in accordance with the evaporative gas concentration (or the change in the evaporative gas concentration). Whether or not there is a leak may be determined by an equation. ΔP2> α · ΔP1 + β

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire system showing an embodiment of the present invention.

FIG. 2 is a sectional view of a canister closing valve.

FIG. 3 is a sectional view of a purge control valve.

FIG. 4 is a characteristic diagram showing a relationship between a purge control valve drive duty and a purge flow rate.

FIG. 5 is a flowchart showing the flow of processing of an air-fuel ratio feedback control routine;

FIG. 6 is a flowchart showing a flow of processing of a purge rate control routine.

FIG. 7 is a diagram showing an example of a full open purge rate map.

FIG. 8 is a flowchart showing a processing flow of a purge rate gradual change control routine.

FIG. 9 is a flowchart showing the flow of processing of an evaporative gas concentration detection routine.

FIG. 10 is a flowchart showing the flow of processing of a fuel injection amount control routine;

FIG. 11 is a flowchart showing the flow of processing of a purge control valve control routine.

FIG. 12 is a flowchart showing the flow of processing of an abnormality diagnosis routine (part 1);

FIG. 13 is a flowchart (part 2) illustrating a flow of processing of an abnormality diagnosis routine;

FIG. 14 is a time chart for explaining a method for measuring the amount of change in evaporative gas concentration.

FIG. 15A is a diagram conceptually showing a map for setting a judgment value KFLGA based on a cooling water temperature, and FIG. 15B is a diagram conceptually showing a map for setting a judgment value KFLGA based on an accumulated purge execution time.

FIG. 16 is a time chart for explaining the relationship between the opening and closing of the purge control valve and the canister closing valve and the change in the fuel tank internal pressure at the time of abnormality diagnosis.

FIG. 17 is a diagram conceptually showing a map for setting correction coefficients BA and BB by evaporative gas concentration.

18A is a diagram conceptually showing a map for setting a determination value KFLGC based on a cooling water temperature, FIG. 18B is a diagram conceptually showing a map for setting a determination value KFLGC based on an accumulated purge execution time, and FIG. ) Is a diagram conceptually showing a map for setting the correction value KFLGK based on the intake air temperature.

[Explanation of symbols]

11 engine (internal combustion engine), 12 intake pipe, 14 throttle valve, 16 fuel injection valve, 17 fuel tank, 18 fuel pump, 20 pressure sensor, 21 evaporative gas purge system, 22 communication pipe, 23 canister, 24 adsorbent, 26 canister closing valve, 30a,
30b: purge passage, 31: purge control valve, 39: control circuit (abnormality diagnosis means, execution condition determination means, determination value setting means, detection value correction means), 45: throttle sensor, 46
... Idle switch, 47 ... Vehicle speed sensor, 48 ... Atmospheric pressure sensor, 49 ... Intake pipe pressure sensor, 50 ... Cooling water temperature sensor, 51 ... Intake air temperature sensor, 53 ... Warning lamp.

Claims (4)

[Claims] 1. A canister for adsorbing evaporative gas generated by evaporating fuel in the fuel tank into a passage communicating the fuel tank with an intake pipe of an internal combustion engine, and purging the evaporative gas from the canister to the intake pipe. And a purge control valve that controls the pressure of the evaporative gas purge system when a predetermined pressure is introduced into the evaporative gas purge system including at least the fuel tank and the canister at the time of abnormality diagnosis and sealed. An abnormality diagnosing means for detecting a subsequent pressure change amount and diagnosing the presence or absence of an abnormality in the evaporative gas purge system based on the detected value, wherein the abnormality diagnosing means includes an air-fuel ratio feedback correction amount deviation during purge execution and a purge. The evaporative gas concentration is obtained from the ratio with the rate, and the amount of change of the evaporative gas concentration and the evaporative gas concentration are both or Abnormality diagnosis apparatus for fuel vapor purge system, characterized in that it has a running condition determining means for determining the execution / stop of the abnormality diagnosis as compared with the determination value change amount of evaporated gas concentration. 2. The apparatus according to claim 1, wherein the abnormality diagnosis unit includes a determination value setting unit that sets the determination value based on at least one of a cooling water temperature, an elapsed time after starting, and a purge execution integrated time. Item 2. An abnormality diagnosis device for an evaporative gas purge system according to Item 1. 3. A canister for adsorbing evaporative gas generated by evaporating fuel in the fuel tank into a passage communicating the fuel tank with an intake pipe of the internal combustion engine, and purging the evaporative gas from the canister to the intake pipe. And a purge control valve that controls the pressure of the evaporative gas purge system when a predetermined pressure is introduced into the evaporative gas purge system including at least the fuel tank and the canister at the time of abnormality diagnosis and sealed. An abnormality diagnosing means for detecting a subsequent pressure change amount and diagnosing the presence or absence of an abnormality in the evaporative gas purge system based on the detected value, wherein the abnormality diagnosing means includes an air-fuel ratio feedback correction amount deviation during purge execution and a purge. Calculate the evaporative gas concentration from the ratio and compare the evaporative gas concentration with the judgment value to execute / stop the abnormality diagnosis An evaporative gas purge system comprising: an execution condition determining means for determining; and a determination value setting means for setting the determination value based on at least one of a cooling water temperature, an elapsed time after starting, and a purge execution integrated time. Abnormal diagnostic device. 4. The apparatus according to claim 1, wherein the abnormality diagnosis unit includes a detection value correction unit configured to correct a detected value of a pressure change amount of the evaporation gas purge system based on at least one of the evaporation gas concentration and the change amount of the evaporation gas concentration. The abnormality diagnosis device for an evaporative gas purge system according to any one of claims 1 to 3.