JP4161856B2 - Evaporative fuel processor diagnostic device - Google Patents

Description

The present invention relates to a diagnostic apparatus for evaporation fuel processor.

  In order to prevent the fuel vapor generated in the fuel tank from being released into the atmosphere, the fuel vapor is led to the canister together with the air through the first passage communicating the fuel tank and the canister (this fuel vapor and Gas mixed with air is called vapor.) Only the fuel particles are adsorbed on the activated carbon in the canister, and the remaining air is discharged from the atmosphere opening of the canister. The purge control valve provided in the intake pipe downstream of the throttle valve) is opened, and the intake pipe pressure that becomes lower than the atmospheric pressure downstream of the throttle valve (this pressure lower than the atmospheric pressure is hereinafter referred to as “negative pressure”). To remove the fuel particles from the activated carbon by the fresh air entering the canister from the atmosphere opening, and the intake pipe downstream of the throttle valve Led by is provided an evaporated fuel processing apparatus that is burned.

  In this case, if a leak hole is made in the middle of the purge passage from the fuel tank to the intake pipe, or if the seal at the joint of the pipe becomes poor, the fuel vapor is released into the atmosphere. Yes. That is, the presence or absence of leakage can be seen by looking at the pressure change after the purge passage from the fuel tank to the intake pipe is closed and the closed space has a pressure difference relative to atmospheric pressure. In order to make the purge passage from the fuel tank to the intake pipe a closed space, a drain cut valve that opens and closes the open port at the atmosphere opening of the canister, and a pressure sensor to observe the pressure change of the gas confined in the closed space A pull-down process is provided to reduce the purge passage from the fuel tank to the intake pipe to a constant pressure using the intake pipe pressure (negative pressure), and after that process, the purge passage from the fuel tank to the intake pipe is reduced as a closed space. The leak-down process is held in the state that is maintained, and the pressure in the purge passage from the fuel tank to the intake pipe is adjusted using a pressure sensor during the leak-down process. And sampling, so that a determination of whether there is a leak on the basis of the pressure sampling value.

When an engine equipped with such an evaporative fuel processing device is mounted on a vehicle, the fuel jumps and the liquid level fluctuates (this phenomenon is called “sloshing” or “slosh”) in the fuel tank due to slalom running or the like. Then, the vapor is suddenly generated, and the internal pressure of the purge passage from the fuel tank to the intake pipe increases. Since leak diagnosis using negative pressure was performed until this sloshing occurred, it may be erroneously determined that there is a leak, so determine whether sloshing has occurred by the pressure sensor, There is one that temporarily interrupts leak diagnosis when sloshing occurs (see Patent Document 1).
JP-A-6-159157

  By the way, the reason why sloshing reduces the accuracy of leak diagnosis is that the amount of pressure change due to sloshing occurs as an error. From this point of view, the inventor of the present invention conducted an experiment and examined the pressure waveform at the time of leak down in which sloshing occurred.If the amount of pressure change due to sloshing during the leak down period can be known, this amount is pressure sampled. For the first time, it was found that the pressure change during the true leak down period can be known by subtracting (correcting) from the value, that is, the error can be eliminated from the pressure sampling value.

This will be described with reference to FIG. 5. When sloshing occurs in the left half of the figure during the leak-down in which sloshing has not occurred (during normal leak-down), and in the right half during sleek-down. 1) Flow path pressure (pressure in the purge passage from the fuel tank to the intake pipe),
2) A change amount (pressure change speed) per predetermined time of the flow path pressure,
3) Pressure change rate for slosh (pressure change rate due to slosh only)
Each waveform is shown as a model.

  During the normal leak down shown on the left side, the pressure change rate always decreases (see the middle stage on the left side of FIG. 5), and this change rate does not increase even when there is a leak hole. Further, since no sloshing occurs, the slosh pressure change rate does not increase (see the lower left part of FIG. 5).

  On the other hand, when sloshing occurs during the leak down, the generation speed of the fuel vapor in the fuel tank becomes transiently high, and when sloshing is settled, it returns to the original state. With the temporary increase in the generation speed of fuel vapor in the fuel tank due to such sloshing, upward protrusions appear in the waveform of the pressure change speed (see the middle section on the right side of FIG. 5).

  In this case, the difference between the pressure change rate measured before the occurrence of sloshing and the pressure change rate exceeding that value is the result of the sloshing effect, that is, the pressure change rate is the difference. Can be considered to be the slosh pressure change rate (see the middle section on the right side of FIG. 5). Then, if this slosh pressure change rate is integrated, the integrated value represents the amount of pressure change due to sloshing (see the bottom row in FIG. 6).

  On the other hand, when the temperature of the fuel tank 1 rises, the amount of fuel evaporation increases, and the pressure in the purge passage from the fuel tank 1 to the purge control valve 11 rises. Performing leak diagnosis by leak-down processing in this state causes an error in the diagnosis result. Therefore, in order to eliminate the influence of the temperature rise from the pressure change at the time of leak down used for leak diagnosis, a vapor monitoring process as shown in FIG. 14 is performed after the leak down process is completed. Here, the vapor monitoring process means that the drain cut valve is opened with the barge control valve closed and the atmosphere is introduced into the purge passage from the fuel tank to the barge control valve, and then the drain cut valve is operated for a period of time t3 (vapor). (Monitoring period) This is a process of closing and closing the purge passage from the fuel tank to the barge control valve, and measuring the pressure change during the period t3 in this sealed state as the temperature rise correction amount (DVP8). Then, by subtracting this temperature increase correction amount (DVP8) from the measured pressure change amount (DVP4-DVP5), the pressure change amount due to the leak down is corrected.

  When sloshing occurs during such a vapor monitoring period t3, the pressure change during the measured vapor monitoring period becomes larger than when no sloshing occurs, resulting in misdiagnosis in the leak diagnosis.

  Therefore, the present invention provides an apparatus capable of obtaining a true pressure rise that is not affected by sloshing in a fuel vapor pressure monitoring apparatus in a sealed state such as a leak down period or a vapor monitoring period even when sloshing occurs. For the purpose.

  It is another object of the present invention to provide a device capable of performing leak diagnosis without extending the leak diagnosis period even if sloshing occurs by performing leak diagnosis based on the obtained true pressure increase.

  On the other hand, the above-mentioned conventional apparatus only takes measures when sloshing occurs during pull-down processing in which the flow path pressure decreases. Cannot be applied as is. In other words, when sloshing occurs during pull-down processing where the flow path pressure decreases, the flow path pressure increases, and when sloshing disappears, the flow path pressure decreases after taking a peak and returns to the value before the occurrence of sloshing. , It gets smaller from that value. Therefore, in the conventional apparatus, when the flow path pressure that has been reduced until then rises on the way, the period until the flow path pressure returns to the value before the occurrence of sloshing is the sloshing occurrence period. It is considered.

  However, when sloshing occurs during the leak down process, the flow path pressure only rises as shown in the right side of FIG. 5 and FIG. 6, and after sloshing ceases, it returns to the value before the occurrence of sloshing. Since there is no possibility, the sloshing judgment method by the conventional apparatus cannot judge the sloshing itself at the time of leak down processing.

  Further, the present invention makes it possible to perform a leak diagnosis without prolonging the leak diagnosis period by estimating the amount of pressure change due to the sloshing when the sloshing occurs. Since the pressure change amount is not estimated, the technical idea is different from the conventional apparatus in which the leak diagnosis period is extended only during the period in which the sloshing occurs.

The present invention relates to a purge passage (2, 4, 6) for evaporated fuel from the fuel tank (1) to the intake passage (8) of the engine, and the pressure in the sealed state of the purge passage (2, 4, 6) ( Pressure detection means (13) for detecting P), and based on this pressure (P), a second pressure (DVP5) temporally after the first pressure (DVP4) in the sealed state of the purge passage. ), The pressure change rate (DEVPRS2) in the sealed state of the purge passage is calculated from the pressure (P), and the pressure change rate (DEVPRS2) in the sealed state of the purge passage is calculated. Then, a pressure change amount (DVPIGL2) from the first pressure to the second pressure due to sloshing generated in the fuel tank (1) is estimated, and the pressure change amount (DVPIGL2) due to the sloshing is used as the first pressure change. A corrected pressure increase (DVP4-DVP5A) is obtained by correcting the measured value (DVP4-DVP5) of the pressure increase from the pressure (DVP4) to the second pressure (DVP5), and this corrected pressure increase (DVP4) -DVP5A) is configured to determine whether or not there is a leak , and means for estimating a pressure change amount (DVPIGL2) from the first pressure to the second pressure due to sloshing The pressure change rate calculating means for calculating the pressure change rate in the sealed state of the purge passage every predetermined period and the pressure change rate (DEVPRS2) in the closed state of the purge passage are used to determine the pressure in the sealed state of the purge passage. Pressure change speed minimum value update means for updating the minimum value of change speed (EVLKMN2), and the pressure change speed (DEVPRS2) for each predetermined period, A slosh pressure change rate calculating means for calculating a difference from the minimum value (EVLKMN2) of slosh as a slosh pressure change rate (DLTP2), and the slosh pressure change rate (DLTP2) from the timing of measuring the first pressure. It comprises a slosh pressure change rate integration means for calculating a value integrated until the timing of measuring the second pressure as the slosh pressure change amount (DVPIGL2) .

Furthermore, the present invention provides a purge passage (2, 4, 6) for the evaporated fuel from the fuel tank (1) to the intake pipe (8) of the engine, and the pressure in the sealed state of the purge passage (2, 4, 6). Pressure detection means (13) for detecting (P), and based on this pressure (P), a second pressure (DVP4) that is later in time from the first pressure (DVP4) in the sealed state of the purge passage. DVP5) is measured, and the pressure rises in time after the third pressure in the sealed state of the purge passage based on the pressure (P) in a section different from the measurement section of the pressure rise. 4 is measured as a temperature rise correction amount (DVP8), and the pressure change rate (DEVPRS2) when the purge passage is sealed is calculated from the pressure (P), and the purge passage is sealed. Pressure change rate (DEVPRS2 The pressure change amount (DVPIGL2) from the third pressure to the fourth pressure due to the sloshing generated in the fuel tank (1) is estimated on the basis of the pressure, and the temperature is calculated based on the pressure change amount (DVPIGL2) due to the sloshing. A correction temperature increase correction amount (DVP8A) is obtained by correcting the increase correction amount (DVP8), and from this first pressure (DVP4) to the second pressure (DVP5) with this correction temperature increase correction amount (DVP8A). The corrected pressure rise (DVP4-DVP5-DVP8A) is obtained by correcting the pressure rise measurement value (DVP4-DVP5), and whether there is a leak based on this corrected pressure rise (DVP4-DVP5-DVP8A). along with configured to perform determination, pressure change amount from the third pressure by sloshing to said fourth pressure (DVPI The means for estimating L2) uses the pressure change rate calculating means for calculating the pressure change rate in the sealed state of the purge passage every predetermined period, and the pressure change rate (DEVPRS2) in the closed state of the purge passage. The pressure change speed minimum value updating means for updating the minimum pressure change speed value (EVLKMN2) in the sealed state of the purge passage, and the difference between the pressure change speed (DEVPRS2) and its minimum value (EVLKMN2) for each predetermined period Is calculated as a slosh partial pressure change rate (DLTP2), and the slosh partial pressure change rate calculation unit (DLTP2) is measured from the timing at which the third pressure is measured to the fourth pressure. Slosh for calculating the value accumulated during the period as the amount of change in pressure of the slosh (DVPIGL2) Pressure change rate integrating means .

  According to the present invention, the pressure increase (DVP4-DVP5, DVP8) from the first pressure in the sealed state of the purge passage from the fuel tank to the engine intake pipe to the second pressure later in time is measured. On the other hand, the pressure change amount (DVPIGL2) from the first pressure to the second pressure due to the sloshing is estimated, and the pressure rise from the first pressure to the second pressure is estimated by the pressure change amount (DVPIGL2) due to the sloshing. Minute (DVP4-DVP5, DVP8) is corrected to obtain the corrected pressure increase (DVP4-DVP5A, DVP8A), so even if sloshing occurs during the leak-down process or the vapor monitoring process, the leak-down period or The amount of pressure increase during the vapor monitoring period can be obtained with high accuracy.

  Further, according to the present invention, it is possible to determine whether or not there is a leak by using the pressure increase (DVP4-DVP5A) that is not affected by the sloshing at the time of the leak down, so that the sloshing can be performed in the state where the leak does not exist. It is possible to avoid a misdiagnosis that a leak exists under the influence of. In addition, even when sloshing has occurred, it is possible to determine whether there is a leak, and the frequency of leak diagnosis can be improved.

  Furthermore, according to the present invention, a pressure increase that is not affected by sloshing at the time of vapor monitoring is obtained as a temperature increase correction amount (DVP8A), and a measured value (DVP4-DVP5) of the pressure increase at the time of leak down with this correction amount. By determining whether or not there is a leak using a value obtained by correcting the above, it is possible to avoid a misdiagnosis that a leak exists due to the influence of sloshing during the temperature rise of the fuel tank.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is an engine control system diagram, and the engine is mounted on a vehicle (not shown).

  In FIG. 1, 1 is a fuel tank, 4 is a canister, and the vapor in the upper part of the fuel tank 1 is guided to the canister 4 through a passage (first passage) 2, and only fuel particles are adsorbed on the activated carbon 4 a in the canister 4. Then, the remaining air is discharged to the outside from the atmosphere opening 5 provided in the vertical lower part of the canister 4 (shown in the upper part of the canister 4 in the figure).

  The canister 4 communicates with an intake pipe 8 downstream of the throttle valve 7 through a passage (second passage) 6, and a normally closed purge control valve 11 driven by a step motor is provided in the passage 6. When the purge control valve 11 is opened in response to a signal from the engine controller 21 under a certain condition (for example, a low load region after warm-up), the air release port of the canister 4 is caused by the negative pressure that develops greatly downstream of the throttle valve 7. From 5, fresh air is introduced into the canister 4. With this fresh air, fuel particles are introduced from the activated carbon 4a together with fresh air into the intake pipe 8 through the purge passage 6, and burned in the combustion chamber.

  On the other hand, a normally open drain cut valve 12 is provided at the atmosphere opening 5 of the canister 4. This drain cut valve 12 is closed at the time of leak diagnosis, which will be described later, and is necessary for making the flow path (purge passages 2, 4, 6) from the purge control valve 11 to the fuel tank 1 into a closed space.

  Further, a pressure sensor 13 is provided in the passage 6 between the canister 4 and the purge control valve 11, and this pressure sensor 13 generates a voltage proportional to the pressure (absolute pressure) of the flow path that is closed at the time of leak diagnosis as shown in FIG. Output as shown in.

  In the engine controller 21 composed of a microcomputer, whether or not there is a leak in the flow path from the fuel tank 1 to the purge control valve 11 is controlled by opening and closing the two valves (purge control valve 11 and drain cut valve 12). Diagnosis is performed while the engine is running. The frequency of leak diagnosis is about once in one operation.

  Here, an outline of the leak diagnosis from the pull-down process and the leak-down process will be described with reference to FIGS.

FIGS. 3 and 4 show how the flow path pressure changes during a leak diagnosis using negative pressure. FIG. 3 shows waveforms when there is no leak and FIG. 4 shows when there is a leak. .
<1> Pull-down process a) When the negative pressure in the intake pipe 8 is sufficiently high (for example, a value smaller than −39.9 kPa with reference to the atmospheric pressure), it is determined that the diagnosis condition is satisfied, and the purge control valve 11 Is closed to temporarily purge, and the passage from the fuel tank 1 to the purge control valve 11 is opened to the atmosphere via the atmosphere opening 5 of the canister 4, and the passage pressure P, that is, the atmospheric pressure at that time is the initial pressure. Store as P ₀ .

  b) Close the atmosphere opening 5 and open the purge control valve 11 to introduce a negative pressure in the intake pipe 8 downstream of the throttle valve 7 to reduce the flow path from the fuel tank 1 to the purge control valve 11.

c) When the difference between the initial pressure P ₀ and the flow path pressure P (this difference is hereinafter simply referred to as “pressure difference”) P ₀ -P is equal to or greater than a predetermined value p2 (for example, p2 is +2 to 3 kPa). Then, the purge control valve 11 is closed. This ends the pull-down process. During the pull-down process, there must be a negative pressure equal to or higher than a predetermined value in the intake pipe 8 downstream of the throttle valve 7.
<2> Leak-down processing a) Pressure difference P ₀ −P when a time (delay time) t5 (for example, 3 to 5 seconds) when the gas flow stops and the pressure loss disappears after the purge control valve 11 is closed. Is sampled (measured) as the pressure DVP4 [kPa] at the start of the leak-down process. DVP4 represents the pressure that was actually withdrawn.

b) When the pressure difference P ₀ -P decreases to a value obtained by subtracting a predetermined value p3 (for example, +0.5 to 2.0 kPa) from the pressure DVP4 at the start of the leak down process, the pressure difference P ₀ -P is ended at the end of the leak down process Sampling (measurement) as the pressure DVP5 [kPa], and the required period until the pressure difference P ₀ -P changes from the pressure DVP4 at the start of the leakdown process to the pressure DVP5 at the end of the leakdown process, as the leakdown period DTIME [sec] To do.

  c) The difference between the pressure DVP4 at the start of the leak-down process and the pressure DVP at the end of the leak-down process (pressure change during the leak-down period), that is, a value obtained by dividing p3 by the leak-down period DTIME is obtained as the leak diagnosis index DVBT. The leak diagnosis index DVBT is compared with the slice level SL2. If there is a leak if the leak diagnosis index DVBT exceeds the slice level SL2 (0.8 to 1.1 kPa), it is determined that there is no leak if the leak diagnosis index DVBT is equal to or less than the slice level SL2.

In the present invention, on the premise of such leak diagnosis, sloshing occurring at the time of leak down is further considered. This will be explained with reference to FIG. 5. The left side of the figure is a normal leak-down state, and the right side is when sloshing occurs during the leak-down.
2) A change amount (pressure change speed) per predetermined time of the flow path pressure,
3) Pressure change rate for slosh (pressure change rate due to slosh only)
Each waveform is shown as a model.

  Normally, at the time of leak down, the pressure change rate always decreases (see the middle stage on the left side of FIG. 5), and this change rate does not increase even when there is a leak hole. Further, since no sloshing occurs, the slosh pressure change rate does not increase (see the lower left part of FIG. 5).

  On the other hand, when sloshing occurs in the middle of leaking down, the generation speed of fuel vapor in the fuel tank becomes transiently high, and when sloshing is settled, it returns to its original state. As the generation rate of fuel vapor in the fuel tank is temporarily increased due to such sloshing, protrusions appear in the waveform of the pressure change rate (see the middle part on the right side of FIG. 5). For this reason, there is a temporary increase in the slosh pressure change rate (see the lower right side of FIG. 5).

  As a result, when the channel pressure waveform at the time of the normal leak down (see the alternate long and short dash line) is superimposed on the channel pressure waveform shown in the upper right side of FIG. 5, the channel pressure when sloshing occurs during the leak down ( (Refer to the solid line) is much larger than the flow path pressure at the time of normal leak down. Therefore, if the leak diagnosis is performed using the flow path pressure when sloshing occurs as it is, an error corresponding to the flow path pressure between the solid line and the alternate long and short dash line is generated in the sampling value of the flow path pressure and the leak diagnosis is performed. Accuracy is reduced.

  Therefore, in the present invention, the amount of pressure change due to sloshing during the leak-down process is estimated. That is, during the leak-down process, the amount of change in the channel pressure per predetermined period (for example, 2 seconds) is measured every predetermined period (for example, every 100 ms) as the pressure change speed DEPRS2, and the minimum value EVLKMN2 of this pressure change speed is determined in advance. It is updated every period, and the difference between the pressure change rate DEVPRS2 during the leak-down process and the minimum value EVLKMN2 of the pressure change rate is calculated as a slosh pressure change rate DLTP2 (see the second stage from the bottom in FIG. 6). The pressure change rate DLTP2 is integrated during the leak-down process to obtain a slosh correction value DVPIGL2 (= slosh pressure change). This is the value shown at the bottom of FIG. Then, as shown in the third row in FIG. 6, the value obtained by subtracting the slosh correction value DVPIGL2 from the pressure DVP5 at the end of the leak down process (shown by a circle) is the pressure DVP5A (at the end of the leak down process after the slosh correction). Calculate as indicated by ●.

  The subsequent processing is the same as in the prior art. That is, a pressure change amount obtained by subtracting the post-slosh corrected pressure DVP5A after the slosh correction from the pressure DVP4 at the start of the leak down process, that is, a value obtained by dividing p3 by the leak down period DTIME is obtained as the leak diagnosis index DVPBT. It is determined whether or not there is a leak based on the leak diagnosis index DVPBT.

  These contents performed by the engine controller 21 will be described in detail based on the following flowchart.

  FIG. 7 is for performing pull-down processing, and this routine is executed at regular intervals.

  In step 1, it is checked whether the leak diagnosis condition is satisfied. The leak diagnosis condition includes that the negative pressure in the intake pipe 8 satisfies the condition (1) a) described above, and that a leak diagnosis stop flag ≠ 1 and a leak diagnosis end flag ≠ 1 described later.

If the leak diagnosis condition is satisfied, the process proceeds to step 2 to check the state of the diagnosis permission flag. Since the diagnosis permission flag is initially set to zero, if the diagnosis permission flag = 0, it is determined that the leak diagnosis condition is satisfied for the first time this time. At this time, the process proceeds to Steps 3 and 4, the purge control valve 11 is closed and the drain cut valve 12 is opened to open the flow path from the purge control valve 11 to the fuel tank 1 to the atmosphere, and then the flow path detected by the pressure sensor 13. The pressure P (= atmospheric pressure) is stored in the memory (RAM) as the initial pressure P ₀ . In this way, by storing the flow path pressure immediately before the start of the pull-down process, even if the flow path pressure immediately before the start of the pull-down process is different for each diagnosis, the determination accuracy of the leak diagnosis is not affected. Can do.

  In step 5, the diagnosis permission flag = 1. In step 6, the purge control valve 11 is opened and the drain cut valve 12 is closed. As a result, the negative pressure in the intake pipe 8 downstream of the throttle valve 7 is guided to the passage 6 and the pressure reduction of the flow path from the fuel tank 1 to the purge control valve 11 is started.

Next time, since the diagnosis condition is satisfied and the diagnosis permission flag = 1, the process proceeds from Steps 1 and 2 to Step 7 to compare the pressure difference P ₀ -P with the predetermined value p2. The predetermined value p2 is set to about 2 to 3 kPa as described above. If the pressure difference P ₀ -P is less than the predetermined value p2, the operation of step 6 is repeated until the pressure difference P ₀ -P becomes equal to or greater than the predetermined value p2. When the pressure difference P ₀ −P becomes equal to or greater than the predetermined value p2, the routine proceeds to step 8 where the purge control valve 11 is also closed, and then the pull-down processing routine is terminated.

  FIGS. 8 and 9 are for performing a leak diagnosis using negative pressure following the pull-down process, and are executed at regular time intervals (for example, every 100 ms).

  In step 11, it is checked whether or not the pull-down process is completed. Since the leak diagnosis is performed after the pull-down process is completed, if the pull-down process is not completed, the routine is terminated without proceeding to the operation of other steps.

  If the pull-down process is completed, the process proceeds to the leak-down process. At this time, in step 12, the t5 elapsed flag (initially set to zero) is checked. The t5 elapsed flag is a flag indicating whether or not the delay time t5 has elapsed since the start of the leak-down period. If the t5 elapsed flag = 0, the process proceeds to step 13 to check whether or not a predetermined time t5 (for example, 3 to 5 seconds) has elapsed since the purge control valve 11 was closed at the pull-down process end timing. t5 gives a delay time from the timing when the purge control valve 11 is closed at the pull-down end timing until the gas flow stops and the pressure loss disappears (see FIGS. 3 and 4). If the predetermined time t5 has not elapsed, the routine ends without proceeding to the operation of other steps.

When t5 has elapsed, in step 14, the pressure difference P ₀ -P is stored in the memory (RAM) as the leak-down start pressure DVP4 [kPa]. At the same time, a timer built in the engine controller 21 is started to start counting up the timer value. In step 15, the t5 elapsed flag = 1 is set and the routine is terminated.

By setting the t5 elapsed flag = 1, at the next control, the process proceeds from step 12 to step 16 to compare the pressure difference P ₀ -P with DVP4-p3-DVPIGL2. The initial value of DVPIGL2 is zero. When the pressure difference P ₀ -P is equal to or less than DVP4-p3-DVPIGL2, it means that the leak-down period DTIME has elapsed. In this case, the operations in steps 20 to 27 in FIG. 9 are performed. When the pressure difference P ₀ -P exceeds DVP4-p3-DVPIGL2, it means that it is in the leak-down period DTIME. In this case, the operations of steps 17 to 19 are performed.

  In step 17, a slosh correction value DVPIGL2 is calculated. The calculation of the slosh correction value DVPIGL2 will be described with reference to the flowchart of FIG.

In FIG. 10 (subroutine of step 17 in FIG. 8), in step 31, the flow path pressure detected by the pressure sensor 13 is used.
DEVPRS2 = PP (2 seconds ago) (1)
However, P: Channel pressure at that timing,
P (2 seconds before): channel pressure 2 seconds before the timing,
The pressure change rate DEPRS2 [kPa / 2 seconds] is calculated by the following formula. 2 seconds is a pressure change rate measurement interval. The reason for increasing the measurement interval in this way is to eliminate the influence of quantization error.

  In step 32, the pressure change rate DEVPRS2 is compared with the minimum value EVLKMN2 of the pressure change rate. Here, the initial value of the minimum value EVLKN2 of the pressure change rate is equal to the pressure change rate DEPRS2. Accordingly, when step 32 is executed first, step 33 is skipped. However, when there is no sloshing, the pressure change rate DEPRS2 continues to decrease regardless of the presence or absence of a leak during the leak-down period as shown in the second stage on the left side of FIG. Accordingly, in the second and subsequent steps 32, unless the sloshing occurs, the process proceeds to step 33, and the minimum value EVLKN2 of the pressure change rate is updated with the latest pressure change rate DEVPRS2 calculated in step 31 of this time.

In step 34, from the pressure change rate DEVPRS2 and the minimum value EVLKMN2 of the pressure change rate,
DLTP2 = DEVPRS2-EVLKMN2 (2)
The slosh partial pressure change rate DLTP2 [kPa / 2 seconds] is calculated by the following formula. Using this slosh partial pressure change rate DLTP2, in step 35, SMDLTP2 = SMDLTP2 (previous value) + DLTP2 (3)
However, SMDLTP2 (previous value): previous value of SMDLTP2,
The integrated value SMDLTP2 [kPa / 2 seconds] of the slosh partial pressure change rate is calculated by the following equation. The expression (3) is an expression for accumulating the slosh pressure change rate DLTP2 every calculation cycle. The initial value of “SMDLTP2 (previous value)” in the first term on the right side of equation (3) is zero.

In step 36, a value obtained by dividing the integrated value of the slosh pressure change rate by 20 is set as the slosh correction value DVPIGL2, that is, DVPIGL2 = SMDLTP2 / 20 (4)
The slosh correction value DVPIGL2 [kPa] is calculated by the following formula.

  The expression (4) is required because the measurement cycle of the slosh partial pressure change rate DLTP2 and the calculation cycle of the slosh partial pressure change rate integrated value SMDLTP2 are different. That is, the slosh partial pressure change rate DLTP2 is measured at intervals of 2 seconds as shown in FIG. On the other hand, the integration interval of the equation (4) is 100 msec, which is equal to the calculation cycle of FIGS. If we look at the time interval of 2 seconds, the speed change speed of the slosh component actually changes only DLTP2 at this time interval, but according to the equation (4), 20 times per second (= 2 seconds ÷ 100 msec) The partial pressure change rate DLTP2 is integrated (see FIG. 11). That is, the integrated value SMDLTP2 on the left side of the equation (4) is a value obtained by integrating DLTP2 20 times in 2 seconds in the calculation. Therefore, a value obtained by dividing the integrated value SMDLTP2 by 20 is a true slosh pressure change integrated value for 2 seconds, that is, a slosh pressure change amount for 2 seconds, which is used as a slosh correction value. is there. Since this is an arithmetic problem, it can of course be configured not to divide by 20 (the measurement cycle of the slosh pressure change rate DLTP2 and the calculation cycle of the slosh pressure change rate integrated value SMDLTP2 may be made the same). ).

  The slosh 3-minute correction value DVPIGL2, which is the amount of change in the slosh pressure, increases every time slosh occurs (every time DLTP2 occurs with a positive value), and is as shown at the bottom of FIG.

  When the slosh correction value DVPIGL2 is calculated in this way, the processing returns to FIG. 8 and the slosh correction value DVPIGL2 and the slice level SL1 are compared in step 18 in step 18. Here, the slice level SL1 is set to the minimum value of the slope of the pressure change during the leak-down period when it is determined that there is a leak in the state where no sloshing occurs in the leak diagnosis according to the conventional technique. Here, the slice level SL1 is set to 0.04 kPa per second, for example. Since SL1 varies depending on engine specifications, it is desirable to determine experimentally.

  If the slosh correction value DVPIGL2 exceeds the slice level SL1, it is erroneously determined that there is a leak only by the amount of pressure change for the slosh even if there is no leak. Cancel flag (initially set to zero) = 1. The leak diagnosis stop flag 1 instructs to stop the leak diagnosis. For example, after a predetermined time elapses, the leak diagnosis can be restarted from the beginning.

On the other hand, when the pressure difference P ₀ -P becomes equal to or smaller than DVP4-p3-DVPIGL2 in step 16, it is the end timing of the leak-down process. At this time, the process proceeds to step 20 in FIG. 9, and the pressure difference P ₀ -P is stored in the memory (RAM) as the end-of-leak-down process pressure DVP5. Further, the timer value of the timer started in step 14 is stored in the memory (RAM) as the leak down period DTIME.

In step 21, a value obtained by subtracting the offset value OFST2 from the slosh correction value DVPIGL2, that is, DVPII = DVPIGL2-OFST2 (5)
The post-quantization error-corrected slosh correction value DVPII is calculated using the following equation.

  Here, the reason why the offset value OFST2 is subtracted from the slosh correction value DVPIGL2 is to remove a quantization error caused by handling the channel pressure as a digital value. OFST2 is a constant value and may be determined in advance through experiments.

In step 22, the post-quantization error corrected slosh correction value DVPII is subtracted from the leak-down process end pressure DVP5 obtained in step 20, that is, DVP5A = DVP5-DVPII (6)
After the slosh correction, the pressure DVP5A at the end of the leak-down process is calculated.

  In step 23, a value obtained by dividing the difference between the leak down process start pressure DVP4 and the slosh corrected leak down end pressure DVP5A by the leak down period DTIME is obtained as a leak diagnosis index DVPBT, that is, by the following equation.

DVPBT = (DVP4-DVP5A) / DTIME (7)
In step 24, the leak diagnosis index DVPBT is compared with the slice level SL2. If the leak diagnosis index DVPBT exceeds the slice level SL2, the routine proceeds to step 25, where it is determined that there is a leak in the flow path from the fuel tank 1 to the purge control valve 11, and the leak flag is set to 1.

  On the other hand, if DVPBT is equal to or less than SL2, the process proceeds from step 24 to step 26, where it is determined that there is no leak in the flow path from the fuel tank 1 to the purge control valve 11, and the leak flag is set to zero.

  Since this leak flag is necessary for failure diagnosis, it is transferred to a nonvolatile memory such as an EEPROM and stored. Alternatively, when the leak flag = 1, the driver may be informed of the information that there is a leak by a warning lamp or a warning buzzer.

  In step 27, the leak diagnosis end flag (initially set to zero when the engine is started) = 1 is set, and both the purge control valve 11 and the drain cut valve 12 are opened, and then the routine is ended. This leak diagnosis end flag = 1 prevents the second leak diagnosis from being performed until the engine is stopped.

  When leak diagnosis using negative pressure is performed in this way, leak diagnosis can be performed even when sufficient positive pressure (pressure higher than atmospheric pressure) does not rise in the fuel tank 1.

Here the operation of this embodiment (claim 1) will be described below with reference to FIG.

  In the present embodiment, DVPIGL2, which is a value obtained by integrating the slosh pressure change rate DLTP2 during the leak down process, is regarded as a pressure fluctuation due to the evaporated fuel generated by the slosh. That is, when the leak down process is performed in a state where no sloshing has occurred, the pressure change rate DEPRS2 during the leak down process decreases with the passage of time (see the middle stage on the left side of FIG. 5). On the other hand, when sloshing occurs, the pressure change rate DEPRS2 has a characteristic that it becomes larger than the previous pressure change rate (see the middle part on the right side of FIG. 5). For this reason, the difference between the minimum pressure change rate EVLKMN2 representing the pressure change rate measured before the occurrence of sloshing and the pressure change rate DEVPRS2 exceeding that value has increased due to the effect of sloshing. It is considered a thing. Then, when the slosh pressure change rate DLTP2, which is the pressure change rate that is the difference from the minimum value of the pressure change rate, is integrated, the pressure change amount due to the sloshing is obtained. In this way, the pressure changed due to the effect of sloshing can be obtained from the integrated value of the slosh pressure change rate.

  By subtracting DVPIGL2, which is a pressure changed due to the effect of sloshing, from the pressure DVP5 at the end of the leak down process (see the circle in FIG. 6), the pressure at the end of the leak down process when no sloshing occurs A certain DVP 5A (see the mark ● in FIG. 6) can be obtained. By determining whether or not there is a leak using this value DVP5A (see steps 23 to 26 in FIG. 9), the following effects can be obtained.

  (A) It is possible to avoid a misdiagnosis that a leak exists due to the effect of sloshing in the absence of a leak.

  (A) Even when sloshing has occurred, it is possible to determine whether there is a leak without extending the leak diagnosis period as in the conventional apparatus, thereby improving the frequency of leak diagnosis. .

If the amount of pressure change caused by sloshing increases before the end of the leak down process, the accuracy of the leak determination will be reduced even if the pressure at the end of the leak down process is corrected with this amount of pressure change. according to an embodiment (claim 7), the pressure variation due to sloshing referred to in the invention of sloshing partial correction value DVPIGL2 (claim 1 representative of the pressure variation caused by the sloshing before leak down processing is completed Since the leak determination is stopped when the estimated value) exceeds the slice level SL1 (see steps 18 and 19 in FIG. 8), it is possible to prevent the determination accuracy from being deteriorated by performing the leak determination in such a case. .

In the computer which is the main component of the engine controller 21, the flow path pressure cannot be handled as an analog value, so it is handled as a predetermined voltage value per bit, and the measured data has a quantization error. The digital value is used to measure the pressure change rate DEPRS2, and the difference between this and the minimum value of the pressure change rate EVLKMN2 is calculated as the slosh pressure change rate DLTP2, and this slosh pressure change rate DLTP2 is calculated during the leak down process. When integrated (see steps 31 to 36 in FIG. 10), a constant integrated value is calculated even when the pressure change rate DEVPRS2 does not actually change. This integrated value is not caused by the slosh but is generated because the output of the pressure sensor 13 is handled as a digital value by the computer. This integrated value, since the calculated regardless the slosh, according to the present embodiment (claim 17), the integrated value as a quantization error component OFST2, sloshing partial correction value DVPIGL2 (claim 1 (Refer to step 21 in FIG. 9), even if the channel pressure is handled as a digital value, the influence of the quantization error is eliminated and the slosh is detected. The calculation accuracy of the minute correction value DVPIGL2 can be improved.

  The flowcharts of FIGS. 12 and 13 are the second embodiment.

  When the temperature of the fuel tank 1 rises, the amount of fuel evaporation increases and the pressure in the flow path from the fuel tank 1 to the purge control valve 11 rises. Performing leak diagnosis by leak-down processing in this state causes an error in the diagnosis result.

  Therefore, in order to eliminate the influence of such a temperature rise, a vapor monitoring process is performed after the leak-down process as shown in FIG. That is, after the leak down process is completed, the drain cut valve 12 is opened while the purge control valve 11 is closed, and atmospheric pressure is introduced into the flow path from the fuel tank 1 to the barge control valve 11 for a certain period t4. Thereafter, the drain cut valve 12 is closed and the flow path from the fuel tank 1 to the barge control valve 11 is sealed, and the pressure change in the closed flow path is monitored (measured) for a certain period of time t3, and the temperature is measured. This is stored as a rise correction amount (DVP8). Here, the period t3 is a vapor monitoring period, and is set to 20 to 60 seconds according to the engine specifications.

  This completes the vapor monitoring process, and corrects the pressure DVP5 at the end of the leak-down process based on the temperature rise correction amount (DVP8) obtained by this vapor monitoring process, thereby increasing the vapor as the temperature of the combustion tank increases. Eliminate impact on leak diagnosis.

  Assuming that such vapor monitoring processing is performed, if sloshing occurs during the vapor monitoring period t3, the temperature rise correction amount (DVP8), which is the monitored pressure change, becomes larger than when sloshing does not occur, and leakage occurs. The correction accuracy of the pressure DVP5 at the end of the down process is lowered.

Therefore, on the premise of performing the vapor monitoring process, in the second embodiment,
In the same manner as in the first embodiment, the slosh correction value DVPIGL2 is calculated in the vapor monitoring period t3, and the slosh correction value DVPIGL2 is subtracted from the temperature increase correction value (DVP8), thereby performing sloshing in the vapor monitoring period t3. Even when this occurs, the temperature correction accuracy of the pressure DVP5 at the end of the leak-down process is increased.

  Further, when the slosh correction value DVPIGL2 in the vapor monitoring period t3 is excessive, the leak diagnosis is cancelled.

  As in the first embodiment, the engine controller 21 first executes a pull-down process routine shown in FIG. 7 when a leak diagnosis condition is satisfied during operation of the engine 10.

  On the other hand, the engine controller 21 executes the routines of the leak-down process and the vapor monitoring process shown in FIGS. 12 and 13 at intervals of 100 ms instead of the leak-down process routines of FIGS. 8 and 9 in the first embodiment.

  In FIG. 12, steps 11 to 15 are the same as steps 11 to 15 of FIG. 8 of the first embodiment. If the t5 elapsed flag is not 0 in step 12 of FIG. 12, the process proceeds to step 5l to check the t4 elapsed flag. The t4 elapsed flag is a flag indicating whether or not the introduction of the atmospheric pressure to the flow path from the fuel tank 1 to the barge control valve 11 performed after the leak-down process is completed, and the t5 elapsed flag = 1. Immediately after that, the t4 elapsed flag is of course zero.

  If the t4 progress flag = 0, the DTIME progress flag is checked in step 52. The DTIME progress flag is a flag indicating whether or not the leak-down process has been completed, and immediately after the t5 progress flag = 1, the DTIME flag = 0.

When the DTIME progress flag = 0, the process proceeds to step 53, and the pressure difference P ₀ −P is compared with DVP4-p3 as in step 16 of FIG. 8 of the first embodiment. Unlike step 16 of FIG. 8, in the second embodiment, DVPIGL2 is not further subtracted from DVP4-p3. If the pressure difference P ₀ -P is larger than DVP4-p3, the routine is immediately terminated without performing the operation in other steps.

When the pressure difference P ₀ -P is equal to or less than DVP4-p3, it is determined that the leak-down process has been completed, and the process proceeds from step 53 to step 54 where the pressure difference P ₀ -P is set as the pressure DVP5 at the end of the leak-down process. Store in memory (RAM). At the same time, the timer value of the timer started in step 14 is stored in the memory (RAM) as the leak down period DTIME.

In step 55, from DVP4-DVP5, which is the pressure increase during the leak-down period, and the leak-down period DTIME,
DVPBT = (DVP4-DVP5) / DTIME (8)
The leak diagnosis index DVPBT is calculated by the following equation, and the leak diagnosis index DVPBT is compared with the slice level SL3 in step 56 of FIG. If the leak diagnosis index DVPBT is not greater than the slice level SL3, the routine proceeds to step 71, where the leak flag = 0 is reset, then the leak diagnosis end flag = 1 is set at step 69, and the purge control valve 11, drain is set at step 70. The routine is ended by opening the cut valve 12 together.

  Here, when the leak diagnosis index DVPBT is not larger than the slice level SL3, the leak diagnosis is ended with the leak flag = 0 for the following reason. The leak diagnostic index DVPBT calculated in step 55 is a diagnostic index based on an apparent pressure change that has not been corrected by temperature rise or sloshing, that is, a diagnostic index obtained from the leak diagnostic algorithm of FIGS. It corresponds to. Comparing this value with the slice level SL3 has the following meaning. That is, as described above, when the temperature of the fuel tank 1 increases, the amount of vapor generated increases, and the flow path pressure P increases accordingly. As a result, the pressure DVP5 at the end of the leak-down process immediately before the vapor monitoring process should also decrease, thereby increasing the leak diagnosis index DVPBT. Even when the flow path pressure P is increased due to the temperature rise of the fuel tank 1, if the leak diagnosis index DVPBT still does not exceed the slice level SL3, it may be determined that no leak exists without performing vapor monitoring processing. it can. Therefore, in this case, the operations of steps 71 and 69 are performed without performing the vapor monitoring process.

  On the other hand, if the leak diagnosis index DVPBT is higher than the slice level SL3 in step 56, the operations after step 57 are performed. The operations in steps 57 to 64 correspond to the processing in the atmosphere introduction period t4 and the vapor monitoring period t3.

  In step 57, the drain cut valve 12 is opened. Further, the DTIME progress flag = 1 indicating that the leak down period DTIME has ended is set.

  In step 58, it is checked whether or not the elapsed time since opening the drain cut valve 12 has reached a predetermined time t4. If the elapsed time is less than t4, the routine is terminated without performing the subsequent steps.

  When the DTIME progress flag is not 0 in step 52 described above (that is, when the DTIME progress flag is 1), the operation of step 58 is skipped and the operation of step 58 is performed. As a result, after the leak down period DTIME ends, the drain cut valve 12 remains open until the atmosphere introduction period t4 elapses, and the introduction of the atmosphere into the flow path from the fuel tank 1 to the barge control valve 11 is continued. .

  When the elapsed time reaches t4 in step 58, the routine proceeds to step 59 where the drain cut valve 12 is closed. Also, the t4 elapsed flag = 1 is set. Thereby, the air introduction period t4 shown in the third row of FIG. 14 ends.

  In the above-described step 51, when the t4 elapsed flag is not 0 (that is, when the t4 elapsed flag is 1), the operations of steps 52 to 59 are skipped and the operation of step 60 is executed. As a result, after the atmosphere introduction period t4 ends, the operations of steps 60 and 61 are repeatedly executed.

  In step 60, the slosh correction value DVPIGL2 is calculated using the subroutine shown in FIG. 10 as in the first embodiment. The slosh correction value DVPIGL2 calculated here is the slosh correction value for the vapor monitoring period calculated from the slosh pressure change rate DLTP2 (see the fourth line in FIG. 14) during the vapor monitoring period (the fifth line in FIG. 14). This is not the slosh correction value during the leak-down period calculated in the first embodiment.

  In step 61, the elapsed time after the drain cut valve 12 is closed is compared with the vapor monitoring period t3. If the elapsed time does not reach t3, the routine is terminated without performing the subsequent steps. During the vapor monitoring period, the calculation of the slosh correction value DVPIGL2 is repeatedly executed.

Elapsed time in step 61 is stored in the memory (RAM) as [kPa] Temperature rise correction amount DVP8 the pressure difference P-P ₀ the process proceeds to step 62 when it reaches the t3.

  In step 63, the post-quantization error corrected slosh correction value DVPII is calculated in the same manner as in step 21 of FIG. The post-quantization-error-corrected slosh correction value DVPII calculated here is also the post-quantization-error-corrected slosh correction value for the vapor monitoring period, and the quantization error during the leak-down period calculated in the first embodiment. It is not the corrected value for the slosh after correction.

  In step 64, a temperature rise correction amount DVP8A (corrected temperature rise correction amount) after slosh correction is calculated from the temperature increase correction amount DVP8 and the post-quantization error corrected slosh correction value DVPII by the following equation.

DVP8A = DVP8-DVPII (9)
In the above formula (6) of the first embodiment, the post-quantization error corrected slosh correction value DVPII is subtracted from the negative value DVP5, whereas in the formula (9), the positive value DVP8 is quantized. The post-error correction post-slosh correction value DVPII is subtracted. This is because the first embodiment corrects the negative pressure, whereas in this embodiment, the positive pressure is corrected as shown in the third row of FIG. In this way, by calculating the post-slosh-corrected temperature rise correction amount DVP8A that eliminates the effect of sloshing, it is possible to accurately grasp the influence of the temperature rise of the fuel tank 1 on the pressure change during the vapor monitoring period. .

  In step 65, the slosh correction value DVPIGL2 calculated in step 60 is compared with the slice level SL4. When the slosh correction value DVPIGL2 exceeds the slice level SL4, the routine proceeds to step 72 where the leak diagnosis stop flag = 1 is set, and then the operation at step 70 is performed.

  If the slosh correction value DVPIGL2 does not exceed the slice level SL4 in step 65, the process proceeds to step 66 and subsequent steps.

  Steps 66 to 69 are parts for performing a leak diagnosis. First, at step 66, a leak diagnosis index DVPBT is calculated from the value obtained by subtracting the slosh corrected temperature increase correction amount DVP8A from the pressure increase at the time of leak down (DVP4-DVP5) and the leak down period DTIME by the following equation.

DVPBT = {DVP4-DVP5-DVP8A × (DTIME / t3)}
(10)
In equation (10), the temperature increase correction amount DVP8A after the slosh correction is multiplied by DTIME / t3 in order to convert the temperature increase correction amount in the vapor monitoring period into the temperature increase correction amount in the leak down period. It is.

  The leak diagnosis index DVPBT calculated in step 55 of FIG. 12 is a value that is not corrected by the temperature rise of the fuel tank 1, whereas the leak diagnosis index DVPBT calculated by the equation (10) is the fuel tank 1 This is a value obtained by adding correction due to pressure increase accompanying sloshing to correction due to temperature increase. Therefore, the leak diagnosis index DVPBT calculated in step 66 is a value that accurately reflects the leak state of the flow path from the fuel tank 1 to the purge control valve 11.

  In step 67, the leak diagnosis index DVPBT obtained in step 66 is compared with the slice level SL5. The slice level SL5 is, for example, 0.8 to 1.1 kPa per second. If the leak diagnosis index DVPBT does not exceed the slice level SL5, the leak flag is reset to 0 in step 71, and if the leak diagnosis index DVPBT exceeds the slice level SL5, the process proceeds from step 67 to step 68 and proceeds to step 68. = 1, and then the operations of steps 69 and 70 are performed, and the routine is terminated.

Thus, according to the second embodiment (claim 8), determine the pressure rise which is not affected by the sloshing during vapor monitoring the temperature rise correction amount DVP8A, during leak down in the correction amount DVP8A Since it is determined whether or not there is a leak using a value obtained by correcting the measured value of the pressure increase (DVP4-DVP5), there is a leak due to the influence of sloshing during the temperature rise of the fuel tank 1. Can be avoided.

In the second embodiment, the DVP8, which is the pressure increase during the vapor monitoring period, is corrected with the slosh correction value. However, in the second embodiment, the first embodiment replaces steps 53 to 55 in FIG. If steps 16 to 19 in FIG. 8 and steps 20 to 23 in FIG. 9 are applied, the influence of sloshing in the leak-down period and the influence of sloshing in the vapor monitoring period are both eliminated, and the leak diagnosis accuracy is further improved. be able to.

  In the second embodiment, the vapor monitoring period is set after the leak-down period, but can be set before the pull-down period.

  In each of the embodiments described above, the flow path pressure P is detected by the pressure sensor 13, but the present invention does not depend on the detection method of the flow path pressure P, and the leak diagnosis is claimed using the flow path pressure P. The present invention is applicable to any fuel vapor processing apparatus that performs the above.

  In each embodiment, the flow path pressure is sampled at the start of the leak down process and at the end of the leak down process, and it is described whether or not there is a leak based on two pressure sampling values at the time of the leak down process. However, it is not limited to this. For example, the present invention is also applied to the case where the leak hole area is obtained based on two pressure sampling values at the start of the leak down process and at the end of the leak down process, and it is determined whether there is a leak based on the leak hole area. can do. In this case, the slosh correction value (the value at the time of pressure sampling) of the present invention may be subtracted from the sampling value of the channel pressure at the end of the leak-down process.

The engine controller 21 is a pressure increase measuring unit according to claim 1 , a pressure change rate calculating unit, a slosh pressure change estimating unit, a pressure increase correcting unit, a leak determining unit, and the pressure according to claim 8. Each function includes an increase measurement unit, a temperature increase correction amount measurement unit, a pressure change rate calculation unit, a slosh pressure change estimation unit, a temperature increase correction amount correction unit, a pressure increase correction unit, and a leak determination unit.

1 is a system diagram of one embodiment. FIG. The output characteristic figure of the pressure sensor 13. FIG. The wave form diagram which shows a pressure change when it is diagnosed that there is no leak at the time of leak diagnosis using negative pressure. The wave form diagram which shows a pressure change when it is diagnosed that there exists a leak at the time of the leak diagnosis using a negative pressure. The wave form diagram which shows each change of the flow path pressure when a sloshing does not generate | occur | produce, a pressure change speed, and a slosh partial pressure change speed. The wave form diagram for demonstrating the effect | action of 1st Embodiment. The flowchart for demonstrating a pull-down process. The flowchart for demonstrating leak diagnosis. The flowchart for demonstrating leak diagnosis. The flowchart for demonstrating the calculation of a slosh part correction value. The characteristic view which shows the relationship between a measurement area and a calculation area. The flowchart for demonstrating the purge monitoring process and leak diagnosis of 2nd Embodiment. The flowchart for demonstrating the purge monitoring process and leak diagnosis of 2nd Embodiment. The wave form diagram for demonstrating correction | amendment of sloshing of 2nd Embodiment.

Explanation of symbols

1 fuel tank 2 passage (first passage)
4 Canister 6 Passage (Second Passage)
7 Throttle valve 8 Intake pipe 11 Purge control valve 12 Drain cut valve 13 Pressure sensor (pressure detection means)
21 Engine controller

Claims (17)

An evaporative fuel purge passage from the fuel tank to the engine intake passage;
Pressure detecting means for detecting the pressure in the sealed state of the purge passage;
A pressure increase measuring means for measuring a pressure increase from the first pressure in the sealed state of the purge passage to the second pressure later in time based on the pressure;
Pressure change rate calculating means for calculating a pressure change rate in the sealed state of the purge passage from the pressure;
A slosh pressure change amount estimating means for estimating a pressure change amount from the first pressure to the second pressure due to sloshing generated in the fuel tank based on a pressure change speed in a sealed state of the purge passage; ,
A pressure increase correction means for correcting the measured value of the pressure increase from the first pressure to the second pressure by the amount of pressure change due to the sloshing to obtain a corrected pressure increase ;
Leak determination means for determining whether there is a leak based on the correction pressure increase ,
The slosh partial pressure change estimating means is
A pressure change rate calculating means for calculating a pressure change rate in a sealed state of the purge passage every predetermined period;
A pressure change rate minimum value updating means for updating a minimum value of the pressure change rate in the sealed state of the purge passage by using the pressure change rate in the sealed state of the purge passage;
A slosh partial pressure change rate calculating means for calculating a difference between the pressure change rate for each predetermined period and its minimum value as a slosh partial pressure change rate;
A slosh partial pressure change rate integration means for calculating a value obtained by integrating the slosh partial pressure change rate from the timing of measuring the first pressure to the timing of measuring the second pressure as the slosh partial pressure change amount;
Diagnostic apparatus for an evaporated fuel treatment device characterized by consisting of. 2. The diagnostic apparatus for an evaporative fuel processing apparatus according to claim 1, wherein the pressure change rate in the sealed state of the purge passage decreases during a pressure increase from the first pressure to the second pressure . The purge passage includes a first passage for guiding the vapor of the fuel tank to the canister and a second passage communicating the canister and an intake pipe downstream of the throttle valve, and a purge control valve for opening and closing the second passage; and a drain cut valve for opening and closing the atmosphere opening port of the canister, these purge control valve, to claim 1 or 2, characterized in that said purging passage and a closed state by a drain cut valve fully closed The diagnostic apparatus of the evaporative fuel processing apparatus of description. The first pressure is a first negative pressure that is adjusted using a negative pressure downstream of the throttle valve in the purge passage, and the second pressure is a point when a predetermined pressure rises from the first negative pressure. the diagnostic device of a fuel vapor processing apparatus according to any one of the things the pressure of the purge passage from claim 1, wherein up to 3 at. The absolute value of the difference between the initial pressure and the pressure in the sealed state of the purge passage is equal to a value obtained by subtracting the amount of pressure change due to the sloshing and the predetermined pressure from the absolute value of the first negative pressure. The diagnostic apparatus for an evaporative fuel processing device according to claim 4 , wherein it is determined that the leak-down period has sometimes elapsed . The correction value obtained by dividing the pressure rise in the leak-down period was calculated as the leakage diagnosis coefficients, according to claim 5, the leak diagnostic coefficient, wherein the determining that there is a leakage is larger than a predetermined value Evaporative fuel processing device diagnostic device. The diagnosis of the evaporative fuel processing device according to any one of claims 1 to 6 , wherein when the amount of pressure change due to the sloshing exceeds a predetermined amount, the determination as to whether or not there is a leak is stopped. apparatus. An evaporative fuel purge passage from the fuel tank to the engine intake pipe;
Pressure detecting means for detecting the pressure in the sealed state of the purge passage;
A pressure increase measuring means for measuring a pressure increase from the first pressure in the sealed state of the purge passage to the second pressure later in time based on the pressure;
Based on the pressure in a section different from the measurement section for the pressure increase, the pressure increase from the third pressure in the sealed state of the purge passage to the fourth pressure later in time is used as the temperature increase correction amount. Temperature rise correction amount measuring means for measuring,
Pressure change rate calculating means for calculating a pressure change rate in the sealed state of the purge passage from the pressure;
A slosh pressure change amount estimating means for estimating a pressure change amount from the third pressure to the fourth pressure due to sloshing generated in the fuel tank based on a pressure change speed in a sealed state of the purge passage; ,
A temperature increase correction amount correcting means for correcting the temperature increase correction amount by the amount of pressure change due to the sloshing to obtain a corrected temperature increase correction amount;
Pressure increase correction means for correcting the measured value of the pressure increase from the first pressure to the second pressure with the corrected temperature increase correction amount to obtain a corrected pressure increase;
Leak determination means for determining whether there is a leak based on the correction pressure increase amount;
With
The slosh partial pressure change estimating means is
A pressure change rate calculating means for calculating a pressure change rate in a sealed state of the purge passage every predetermined period;
A pressure change rate minimum value updating means for updating a minimum value of the pressure change rate in the sealed state of the purge passage by using the pressure change rate in the sealed state of the purge passage;
A slosh partial pressure change rate calculating means for calculating a difference between the pressure change rate for each predetermined period and its minimum value as a slosh partial pressure change rate;
A slosh partial pressure change rate integration means for calculating a value obtained by integrating the slosh partial pressure change rate from the timing of measuring the third pressure to the timing of measuring the fourth pressure as the slosh partial pressure change amount;
It is made of the diagnostic device of the evaporation fuel processor you said. 9. The diagnostic apparatus for an evaporative fuel processing apparatus according to claim 8 , wherein the pressure change rate in the sealed state of the purge passage decreases during a pressure increase from the third pressure to the fourth pressure . The first pressure is a first negative pressure that is adjusted using a negative pressure downstream of the throttle valve in the purge passage, and the second pressure is a point when a predetermined pressure rises from the first negative pressure. 10. The evaporative fuel processing apparatus diagnosis apparatus according to claim 8 , wherein the pressure of the purge passage in the fuel tank is a pressure of the purge passage . The leak-down period has elapsed when the absolute value of the difference between the initial pressure and the pressure in the sealed state of the purge passage is equal to the absolute value of the first negative pressure minus the predetermined pressure. diagnostic apparatus for an evaporated fuel treatment device according to claim 10, characterized in that determining the. The correction value obtained by dividing the pressure rise in the leak-down period was calculated as the leakage diagnosis factor, of claim 11, the leak diagnostic coefficient, wherein the determining that there is a leakage is larger than a predetermined value Evaporative fuel processing device diagnostic device. The diagnosis of the evaporative fuel processing device according to any one of claims 8 to 12 , wherein when the amount of pressure change due to the sloshing exceeds a predetermined amount, the determination as to whether or not there is a leak is stopped. apparatus. The said 3rd pressure is atmospheric pressure, The said 4th pressure is the said purge passage pressure when the predetermined period passes from this 3rd pressure, The Claim 11 or 12 characterized by the above-mentioned. Diagnostic device for evaporative fuel treatment equipment. 15. The diagnostic apparatus for an evaporated fuel processing apparatus according to claim 14, wherein the predetermined period is provided after the leak-down period has elapsed . 16. The diagnostic apparatus for an evaporated fuel processing apparatus according to claim 14, wherein the corrected temperature increase correction amount is multiplied by a ratio between the leak-down period and the predetermined period . The evaporated fuel processing apparatus according to any one of claims 1 to 16, wherein when a flow path pressure is handled as a digital value, a quantization error is subtracted from an estimated value of a pressure change amount due to sloshing. Diagnostic equipment.

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