JP2000018104A - Abnormality diagnostic systems of pressure sensor and vapor fuel supply passage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow abnormality diagnosis of a pressure sensor disposed in a vapor fuel supply passage at high negative pressure where abnormality diagnosis of the passage cannot directly be performed. SOLUTION: If a sensor output value ftp at establishment of determination conditions is larger than a predetermined value, i.e., at high negative pressure, the pressure is adjusted for determining leakage after decreasing the negative pressure. After starting monitor of the leakage determination or during period a for decreasing the negative pressure, the sensor abnormality is determined. The abnormality diagnosis of the vapor fuel supply passage is performed together with the sensor abnormality diagnosis. The sensor abnormality determination may be performed during the period b from the start of monitoring leakage determination to the end of monitoring. The sensor abnormality determination may also be performed based on the monitor values in the periods a', b' starting immediately after engine start.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality diagnosis of a pressure sensor which is disposed in an evaporative fuel supply path for supplying evaporative fuel generated in a fuel tank to an intake passage of an engine and detects a pressure in the evaporative fuel supply path. The present invention relates to an apparatus and an apparatus for diagnosing an abnormality in a fuel supply path.

[0002]

2. Description of the Related Art An evaporative fuel supply path is provided for communicating an upper surface of a fuel tank of an engine mounted on a vehicle with an intake passage of the engine, and a canister is provided in the passage. A purge valve is provided between the canister and the intake passage. Is provided, the evaporated fuel generated in the fuel tank is once adsorbed to the canister, the purge valve is opened in a predetermined operation region, and the evaporated fuel in the canister is discharged to the intake passage together with the outside air from the atmosphere open passage at the intake negative pressure. 2. Description of the Related Art An evaporative fuel supply device adapted to supply the fuel is conventionally known.

As a method of diagnosing a failure of the fuel vapor supply apparatus, at the time of diagnosis, a purge bubble is opened, a suction negative pressure is drawn into a fuel vapor supply path, and evaporation is determined depending on whether the pressure in the path drops to a predetermined negative pressure. Diagnose severe leaks (large leaks) caused by poor connection of the fuel supply path or improper closing of the barge valve, and close the purge valve when the pressure in the path has decreased to a predetermined negative pressure to seal the evaporative fuel supply path. Diagnosis of small leaks (small leaks) due to cracks in the evaporative fuel supply path, etc., based on the degree of pressure return in the evaporative fuel supply path after sealing.

Further, as an apparatus for diagnosing whether or not a pressure sensor for detecting a pressure in a path (tank pressure) for such a failure diagnosis is functioning normally, Japanese Patent Laid-Open No. 5-1 is disclosed.
As described in Japanese Patent No. 95895, there has been proposed a device that determines that the pressure sensor is abnormal when a change in the sensor output value within a predetermined time after the engine is started is smaller than a predetermined value.

[0005]

In the failure diagnosis of the evaporative fuel supply device, an accurate diagnosis cannot be made unless the pressure sensor disposed in the evaporative fuel supply path is functioning properly.
Then, the pressure sensor may cause a sticking failure in which the sensor output value sticks to a substantially constant value and does not operate. Therefore, it is necessary to diagnose whether or not an abnormality such as a sticking failure has occurred in the pressure sensor. Therefore, when performing the diagnosis of the large leak and the small leak in the evaporative fuel supply path, it is conceivable to simultaneously perform the sensor abnormality diagnosis based on whether or not the degree of change in the output value of the pressure sensor is equal to or more than a predetermined value. In the above-described conventional method, when the change in the sensor output value within a predetermined time after starting the engine is smaller than the predetermined value, it is determined that the pressure sensor is abnormal. Is large, it is difficult to set a threshold value for determining that the sensor is abnormal. Eventually, it is impossible to accurately determine a sensor abnormality such as a sticking failure.

[0006] By the way, in the abnormality diagnosis of the fuel vapor supply path, in a predetermined operating state of the engine, first, the purge valve is further opened from the opening of the normal purge control to reduce the intake negative pressure into the fuel vapor supply path. A large leak is diagnosed based on the degree of decrease in the pressure in the passage at that time, and the purge valve is slightly opened by the purge control in a state where the intake negative pressure is high as in an idling state, and the inside of the evaporative fuel supply passage is diagnosed. If this is done while the pressure of the fuel tank is considerably reduced, the pressure in the passage will be too low, the negative pressure will be too high, and the fuel tank will be dented. Therefore,
The path abnormality diagnosis is not performed when the pressure in the fuel vapor supply path is low, but is performed when the pressure in the fuel vapor supply path becomes high to some extent. For this reason, when performing the abnormality diagnosis of the pressure sensor at the same time as the abnormality diagnosis of the evaporative fuel supply path, the abnormality diagnosis cannot be performed also for the pressure sensor until a normal execution condition for the path abnormality diagnosis is satisfied.

However, for the pressure sensor, it is essential that the pressure sensor be normal in order to accurately diagnose the path abnormality. Therefore, the pressure sensor should normally be diagnosed before the path abnormality diagnosis. Therefore, there is a demand to quickly execute the pressure sensor abnormality diagnosis without waiting for the path abnormality diagnosis.

Therefore, separately from the path abnormality diagnosis, the intake negative pressure is drawn into the evaporative fuel supply path to reduce the path pressure,
It is conceivable to make a sensor abnormality determination based on the degree of change in the pressure sensor output value at that time.In this case, too, the intake air pressure is high, the pressure in the evaporative fuel supply path is considerably reduced, and the intake air is further reduced. If the negative pressure was pulled in, the situation that the negative pressure would become too large and the fuel tank would dent would still occur.In the end, the path abnormality judgment was executed when the evaporative fuel supply path was in a high negative pressure state. If not, the sensor abnormality determination cannot be executed.

Accordingly, it is an object of the present invention to perform an abnormality diagnosis of the pressure sensor disposed in the evaporative fuel supply path even when the path abnormality diagnosis is not performed in a high negative pressure state in the evaporative fuel supply path. is there.

[0010]

According to the first aspect of the present invention, there is provided an apparatus comprising:
A pressure sensor disposed in an evaporative fuel supply path for supplying evaporative fuel generated in the fuel tank to an intake passage of the engine and detecting a pressure in the evaporative fuel supply path; and an evaporative fuel path when a predetermined determination condition is satisfied. Pressure adjusting means for adjusting the introduction of the intake negative pressure and the introduction of the atmospheric pressure into the evaporative fuel supply path so as to change the internal pressure for a predetermined period, and the pressure sensor output value of the predetermined period or after the passage of the period. An abnormality diagnosis device for a pressure sensor, comprising: a sensor abnormality determination unit configured to determine abnormality of the pressure sensor based on a degree of change, wherein a detection value of a pressure in the path when a predetermined condition is satisfied is greater than a predetermined value. Is adjusted in advance so that the in-path pressure changes in the negative pressure decreasing direction. If the detected value of the in-path pressure when the predetermined condition is satisfied is a negative pressure larger than the predetermined value, the There when the degree of change in the pressure sensor output value after between the adjustment time period or said period to change in the negative pressure decreasing direction is smaller than a predetermined degree, it is obtained so as to determine that the pressure sensor is abnormal.

According to this device, after the engine is started, the operating state of the engine (rotational speed, load, water temperature, etc.) corresponds to a state in which the degree of change in the pressure in the evaporative fuel supply path substantially corresponds to a change in the degree of opening of the purge valve. When this happens, it is determined that the condition for sensor abnormality determination has been satisfied. When the detected value of the pressure in the path (pressure sensor output value) at the time when the determination condition is satisfied is a negative pressure larger than a predetermined value, the intake negative pressure in the evaporative fuel supply path is decreased in a direction in which the negative pressure decreases. The introduction of the pressure and the introduction of the atmospheric pressure are adjusted, and when the degree of change in the output value of the pressure sensor after the adjustment period or after the adjustment period is smaller than a predetermined degree, it is determined that the pressure sensor is abnormal. In this case, if the intake negative pressure is further drawn in while the evaporative fuel supply path is in a high negative pressure state, the negative pressure becomes too large, causing a problem such as the fuel tank being dented. Since the adjustment of the pressure in the path for the pressure sensor abnormality determination is performed in the direction of decreasing the negative pressure, the pressure is quickly increased after the start without the problem that the negative pressure becomes too large and the fuel tank is dented. Diagnosis of sensor abnormality can be performed.

According to a second aspect of the present invention, in the pressure sensor abnormality diagnosing apparatus according to the first aspect, the pressure sensor output value is changed based on the degree of change in the pressure sensor output value during the period of adjusting the pressure in the path to change in the negative pressure decreasing direction. Thus, the sensor abnormality is determined. During the period in which the pressure in the path is adjusted to change in the negative pressure decreasing direction, the pressure in the evaporative fuel supply path is forcibly changed by adjusting a purge valve or the like. It is easy to set a threshold value for the degree of change in the output value, and accurate sensor abnormality determination can be performed promptly.

According to a third aspect of the present invention, in the pressure sensor abnormality diagnosis apparatus according to the first aspect, when the detected value of the pressure in the path when the predetermined condition is satisfied is a negative pressure equal to or less than a predetermined value, Alternatively, when the detected value of the pressure in the path when the predetermined condition is satisfied is a negative pressure larger than the predetermined value, the detected value of the pressure in the path is adjusted to the predetermined value by adjusting the pressure in the path to temporarily change in the negative pressure decreasing direction. When the negative pressure becomes less than or equal to the second predetermined value, the pressure in the path is adjusted to increase in the negative pressure increasing direction, and then the negative pressure is adjusted to be maintained for a predetermined period. When the detected value of the in-path pressure at the time when is established is a negative pressure equal to or less than a predetermined value, from the start of the adjusting operation of changing the in-path pressure in the negative pressure increasing direction,
Based on the degree of change in the pressure sensor output value during the period up to the end of the adjustment operation for maintaining the negative pressure of the path pressure for a predetermined period, a sensor abnormality determination is performed, and the detected value of the path pressure at the time when the predetermined condition is satisfied is determined. When the negative pressure is larger than the predetermined value, from the start of the adjusting operation of temporarily changing the pressure in the path in the negative pressure decreasing direction, the adjusting operation of changing the pressure in the path in the negative pressure increasing direction and then maintaining the negative pressure for a predetermined period of time. The sensor abnormality determination is performed based on the degree of change in the pressure sensor output value during the period up to the end.

According to this device, when the detected value (pressure sensor output value) of the pressure in the path when the predetermined condition is satisfied is a negative pressure equal to or less than the predetermined value, the pressure in the path is equal to or higher than the second predetermined value. Adjustment is performed so as to change in the negative pressure increasing direction up to the negative pressure, and then adjustment is performed so that the negative pressure is maintained for a predetermined period, and the adjusting operation is performed so that the pressure in the path changes in the negative pressure increasing direction. From the start to the end of the adjustment operation for adjusting the negative pressure to be maintained for a predetermined period, based on the degree of change in the pressure sensor output value, a sensor abnormality determination is performed, and the degree of change in the pressure sensor output value is determined by a predetermined value. When the degree is smaller than the degree, it is determined that the pressure sensor is abnormal. In this case, a pressure change for sensor abnormality diagnosis can be made in the evaporative fuel supply path within a range where the negative pressure is not high enough to cause a problem such as a depression of the fuel tank, and accurate sensor abnormality determination can be performed.

Further, when the detected value of the pressure in the passage when the predetermined condition is satisfied is a negative pressure larger than the predetermined value, the intake negative pressure is introduced into the evaporative fuel supply passage in a direction in which the negative pressure decreases. After the adjustment of the introduction of the atmospheric pressure is performed, the adjustment is performed so that the pressure in the path changes in the negative pressure increasing direction to a negative pressure equal to or more than the second predetermined value, and thereafter, the adjustment is performed so that the negative pressure is maintained for a predetermined period. Is performed, from the start of the adjusting operation for temporarily changing the pressure in the path in the negative pressure decreasing direction to the end of the adjusting operation for changing the pressure in the path in the negative pressure increasing direction and then maintaining the negative pressure for a predetermined period. A sensor abnormality determination is performed based on the degree of change in the pressure sensor output value during the period. When the degree of change in the pressure sensor output value is smaller than a predetermined degree, it is determined that the pressure sensor is abnormal. In this case, the adjustment is once made in the direction in which the negative pressure is reduced, so that the sensor is diagnosed within a range in which the inside of the evaporative fuel supply path is not in a high negative pressure state that causes a problem such as a depression of the fuel tank. The pressure change of (1) can be created to perform accurate sensor abnormality determination.

According to a fourth aspect of the present invention, in the pressure sensor abnormality diagnostic apparatus according to the third aspect, the pressure in the path is increased from the state in which the detected value of the pressure in the path is a negative pressure equal to or less than a predetermined value. Then, based on the degree of change of the output value of the pressure sensor during a period in which the pressure is changed to maintain the negative pressure, the abnormality determination of the evaporative fuel supply path is performed together with the determination of the sensor abnormality. During the period in which the pressure in the path is changed in the negative pressure increasing direction, a large leak in the evaporative fuel supply path can be diagnosed based on whether the pressure in the path falls to a predetermined negative pressure, and then the negative pressure is maintained. During the adjustment period, a small leak in the fuel vapor supply path can be diagnosed based on the degree of return of the pressure in the fuel vapor supply path.

According to a fifth aspect of the present invention, in the pressure sensor abnormality diagnosis apparatus according to the second or third aspect, the monitoring of the output value of the pressure sensor for determining the abnormality of the sensor is started immediately after the engine is started. Things. By starting sensor monitoring immediately after the engine is started, the monitoring range is expanded, and erroneous determination due to oversight can be prevented.

A pressure sensor disposed in an evaporative fuel supply path for supplying evaporative fuel generated in a fuel tank to an intake passage of an engine and detecting a pressure in the evaporative fuel supply path is provided. A pressure adjusting means for adjusting the introduction of intake negative pressure and the introduction of atmospheric pressure into the evaporative fuel supply path so as to change the pressure in the evaporative fuel path for a predetermined period when the operation state of the engine satisfies a predetermined condition; An evaporative fuel supply path abnormality diagnosis device, comprising: a path abnormality determining means for determining an abnormality of the evaporative fuel supply path based on the degree of change in the output value of the pressure sensor after the predetermined period or after the elapse of the predetermined period. When the detected value of the pressure in the path at the time when the condition is satisfied is a negative pressure larger than a predetermined value, the pressure in the path is adjusted to change in the negative pressure decreasing direction in advance, and when the predetermined condition is satisfied, When the detected value of the path in the pressure is a predetermined value greater than the negative pressure, after being adjusted to route the pressure is changed to a negative pressure decreasing direction, in which to perform the path abnormality determination in the predetermined period.

According to this device, when the operating condition of the engine satisfies a predetermined condition, and when the detected value of the pressure in the path when the predetermined condition is satisfied is a negative pressure larger than the predetermined value,
After the introduction of the intake negative pressure and the introduction of the atmospheric pressure are adjusted so that the pressure in the path changes in the negative pressure decreasing direction in advance, adjustment is made to change for a predetermined period for abnormality determination, and the path abnormality determination is performed during the adjustment period. Will be In this case, if the intake negative pressure is further drawn in while the evaporative fuel supply path is in a high negative pressure state, a problem such as the negative pressure becoming too large and the fuel tank being dented occurs. Since the adjustment is performed in the direction to decrease the negative pressure in advance, the abnormality diagnosis of the evaporative fuel supply path can be executed immediately after the start without the problem that the negative pressure becomes too large and the fuel tank is dented.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic system of an engine to which the present invention is applied. In this figure, reference numeral 1 denotes an engine body having a cylinder, and a combustion chamber 2 of the cylinder.
An intake port 3 opened and closed by an intake valve and an exhaust port 4 opened and closed by an exhaust valve are opened, and a spark plug 18 is arranged at the top of the combustion chamber 2.

An intake passage 5 is connected to the intake port 3, and an exhaust passage 13 is connected to the exhaust port 4.
The intake passage 5 is provided with an air cleaner 6, an air flow sensor 7, a throttle valve 8, and a surge tank 9 in this order from the upstream side, and an injector (fuel injection valve) 10 for injecting fuel near the intake port 5. Is provided. Further, an ISC passage 11 that bypasses the throttle valve 8 is provided.
Is provided with an ISC valve 12 for adjusting the air flow rate in the passage 11 for controlling the idle speed. On the other hand, an O ₂ sensor 14, a catalyst device 15, and the like are provided in the exhaust passage 13. The intake passage 5 is provided with a throttle opening sensor 16 for detecting the opening of the throttle valve 8, and the engine body 1 includes a crank angle sensor 17 for detecting a rotation angle of a crankshaft (not shown) of the engine. A water temperature sensor 19 for detecting the temperature of the cooling water of the engine is provided.

The fuel system for supplying fuel to the injector 10 includes a fuel tank 20, a fuel pump 21, a fuel supply passage 22, and a return passage 23. The fuel pump 21 passes through the fuel supply passage 22 from the fuel tank 20. Fuel is sent to the injector 10. The fuel filter 2 is provided in the fuel supply passage 22.
4 are interposed. The return passage 23 is provided with a pressure regulator 25 for adjusting the fuel pressure in accordance with the intake pressure. In the fuel tank 20, a float type remaining amount sensor (oil level sensor) 26 is disposed on the upper surface of the fuel tank 20 so as to detect the remaining amount of the fuel based on the position of the float floating on the liquid surface of the fuel. Have been.

Further, an evaporative fuel supply system for supplying the evaporative fuel generated in the fuel tank 20 to the intake side is provided. The evaporative fuel supply system includes a purge passage 30 that constitutes an evaporative fuel supply path.
Has an upstream end connected to the upper part of the fuel tank 20 and a downstream end connected to the surge tank 9 of the intake passage 5. A canister 31 for adsorbing the evaporated fuel is provided in the middle of the purge passage 30, and an atmosphere opening passage 32 is connected to the canister 31.

The purge passage 30 between the fuel tank 20 and the canister 31 is provided with a check valve 33 for releasing the tank internal pressure to the canister 31 when the pressure in the fuel tank 20 increases, and is provided in parallel with the check valve 33. An opening / closing valve (hereinafter, referred to as a TPCV valve) 34 composed of a solenoid valve is provided. The air release passage 32 is provided with an air filter 35 and a check valve 36, and an open / close valve (hereinafter, referred to as a CDCV valve) 37 composed of a solenoid valve.

The purge passage 30 between the canister 31 and the surge tank 9 is provided with a purge valve 38 composed of a duty solenoid valve for adjusting a supply amount (purge amount) of a purge gas containing evaporated fuel. The evaporative fuel supply system is provided with a fuel tank pressure sensor (hereinafter referred to as an FTP sensor) 39 for detecting the pressure in the fuel tank 20 as the pressure in the purge passage 30 on the fuel tank 20 side of the purge valve 38. I have.
These purge valve 38, TPCV valve 34 and C
The DCV valve 37 is connected to the engine control unit (E
CU) 40.

The ECU 40 includes an air flow meter 7, an O
₂ sensor 14, throttle opening sensor 16, crank angle sensor 17, water temperature sensor 19, remaining amount sensor 26,
FTP sensor 39, atmospheric pressure sensor 41 for detecting atmospheric pressure
And the like are input. The ECU 40 controls the injector 10, the ignition plug 18, the ISC valve 12, and the like based on the input information, and also controls the purge valve 38, the TPCV valve 34, the CDCV valve 37.
The purge control is performed to supply the fuel adsorbed to the canister 31 to the intake passage 5 in a specific motion region of the engine, and a process of diagnosing abnormality of the purge system such as the purge passage 30 is performed. The abnormality diagnosis process of the sensor 39 is performed.

In the abnormality diagnosis of the purge system, when predetermined conditions based on the engine speed, charging efficiency, water temperature and the like are satisfied after the engine is started, the intake passage 5 is inserted into the purge passage 30.
In the state where the negative pressure is introduced and the purge passage 30 is further sealed, the degree of pressure increase in the purge passage 30 within a preset diagnosis time, for example, 25 seconds, is measured by the FTP sensor 3.
9 based on the detection signal. That is, by opening the TPCV valve 34 and the purge valve 38 and closing the CDCV valve 37 as shown by the solid line in FIG. 2, the purge passage 30 is opened between the fuel tank 20 and the intake passage 5, and the atmosphere side is opened. The open passage 32 is shut off, the negative pressure of the intake passage 5 is introduced into the purge passage 30, and the internal pressure of the purge passage 30 (pressure in the passage) is reduced by -200 mmAq.
Then, the purge valve 38 is closed to close the purge passage 30 in a negative pressure state. Then, a detection pressure (first detection pressure) which is an output value of the FTP sensor 39 when a predetermined reference time (for example, 25 seconds) has elapsed since the purge valve 38 was opened, and then a predetermined diagnosis time has elapsed. Pressure at the time of detection (second detection pressure)
Are read, and the first detected pressure is subtracted from the second detected pressure to determine the degree of pressure increase in the purge passage 30 within the diagnosis time e. Then, the calculated value of the degree of pressure rise within the diagnosis time e is compared with a reference value set in accordance with the operating state, and when the degree of pressure rise is larger than the reference value, the negative pressure in the purge passage 30 is reduced. It is determined that there is a failure in which the pressure cannot be properly maintained, for example, a minor failure (small leak) such as formation of a crack in the purge passage 30.

However, the FTP when the above determination condition is satisfied
The internal pressure ftp (pressure sensor output value) of the purge passage 30 detected by the sensor 39 is, for example, a predetermined value (−19).
When the negative pressure is greater than 0 mmAq to -150 mmAq), as shown by the broken line in FIG.
While the TPCV valve 34 is kept open for a predetermined period of time.
Is opened, the purge valve 38 is fully closed, and the pressure in the purge passage 30 (pressure in the passage) is temporarily reduced to a negative pressure equal to or lower than the predetermined value. Then, after that, the purge valve 38 is opened again, the CDCV valve 37 is closed, and the pressure in the passage is reduced to −.
The pressure is reduced to a negative pressure of about 200 mmAq, the purge passage 30 is sealed, and the small leak is determined.

Further, the purge valve 38 is opened so that the pressure in the passage is reduced to a negative pressure of about -200 mmAq,
When the CV valve 37 is closed, the time required to bring the inside of the purge passage 30 into a predetermined negative pressure state is measured, and when this measurement time is longer than a preset reference time (for example, 30 seconds). Determines that there is a serious failure (large leak) due to poor connection of the purge passage 30 and the like, and the first detection pressure of the FTP sensor 39 at the time when the reference time has elapsed since the purge valve 38 was opened. When the first detected pressure is higher than the reference pressure, a large leak has occurred due to a failure of the purge valve 38 that cannot be fully closed. Is determined.

Also, at the time of failure diagnosis of the evaporative fuel supply system, a sampling time set to a time shorter than the above diagnosis time, for example, a control cycle at the time of failure diagnosis described later, or about 1 second irrespective of this control cycle. For each sampling performed, the amount of pressure change in the purge passage 30 is
Calculated based on the detection signal of the sensor 39, and by multiplying the degree of pressure rise in the purge passage 30 within a diagnosis time by a predetermined coefficient, or the like, the pressure rises to a larger value as the degree of pressure rise increases. A threshold value for judging the degree of shaking is set. Then, the maximum value of the pressure change amounts calculated for each sampling time in the diagnosis time is obtained, and the maximum value is compared with the threshold value for determining the degree of shaking. If the maximum value of the pressure change amount is large, it is determined that a large oil level sway has occurred in the fuel tank 20 and the vaporization of the fuel is easily promoted, and the failure determination of the evaporative fuel supply system is stopped. Further, it is determined whether or not the oil level swing is large based on the output signal of the remaining amount sensor 26, and when the oil level swing is large, it is determined that the fuel vaporization is easily promoted,
The failure determination of the evaporative fuel supply system is stopped.

The abnormality diagnosis of the FTP sensor 39 is for detecting a fixing failure in which the sensor output value of the FTP sensor 39 does not move.
Monitoring of the sensor output value of the P sensor 39 is started. Then, the above-described determination condition is satisfied, and at that time, the pressure sensor output value ftp is, for example, -190 mmAq to -150 mmAq.
After the TPCV valve 34 and the purge valve 38 are opened and the CDCV valve 37 is closed as shown by the solid line in FIG. 2 and immediately after the monitoring of the large leak determination is started, or The pressure sensor output value ftp when the above-mentioned determination condition is satisfied is lower than the above-mentioned predetermined value, for example, and the CDC
After the TPCV valve 34 is opened and the purge valve 38 is fully closed while the V valve 37 is kept open, the failure of the FTP sensor 39 to be fixed depends on whether the change in the pressure sensor output value ftp is equal to or greater than a predetermined degree. Is determined.

The determination of the sticking failure is based on the sensor output value ftp monitored during the period a 'after the start of the engine shown in FIG.
It is determined in the period a shown in FIG. 2 whether or not the difference between the maximum value ftpmax and the minimum value ftpmin is equal to or more than a predetermined value (predetermined degree) S. The maximum value ftpmax
When the difference between the FTP sensor 39 and the minimum value ftpmin is smaller than the predetermined value S, it is determined that the FTP sensor 39 is abnormal. In addition,
In this case, the monitor for determining the sticking failure is shown in FIG.
May be executed after the period a shown in FIG. At least the maximum value ftpma based on the monitor value during the period a
When the difference between x and the minimum value ftpmin is smaller than the predetermined value S, it can be determined that the FTP sensor 39 is abnormal.

The abnormality determination of the FTP sensor 39 is performed based on the monitored value of the sensor output value ftp during the period b 'shown in FIG. 2, that is, the period from the start of the engine to the end of the leak determination of the purge system. It may be.
In this case, after the engine is started, the monitoring of the sensor output value ftp of the FTP sensor 39 is started, and after the monitoring of the large leak determination is started, at least a period until the large leak determination ends in a period b shown in FIG. Monitoring, and then the maximum value ftpm of the sensor output value ftp
When the difference between ax and the minimum value ftpmin is smaller than a predetermined value S, it is determined that the FTP sensor 39 is abnormal. In this case, the monitor for determining the sticking failure is
It may be executed after entering the period b shown in FIG. At least the maximum value ftp based on the monitor value during the period b
When the difference between max and the minimum value ftpmin is smaller than the predetermined value S, it can be determined that the FTP sensor 39 is abnormal.

FIGS. 3 to 7 are flow charts for executing a process for diagnosing an abnormality in the fuel vapor supply system. When the process is started, it is determined in step S1 whether or not the engine is operating, and it is determined to be YES. When step S
In step 2, the count value of a pressure reduction timer Tpgon for counting a reference time d for keeping the inside of the purge passage 30 in a negative pressure state is reset to zero.

Next, in step S3, it is determined whether or not the detected value of the throttle opening tvo is smaller than a preset reference opening a. The reference opening a is set to a value corresponding to the light load operation of the engine with the throttle valve 8 opened by about 20 to 25%. If the determination in step S3 is NO, the engine is in a high load operation state, the intake air flow rate is large, and the inside of the purge passage 30 is set to a predetermined negative pressure state for failure diagnosis of the evaporative fuel supply system. Step S4
, The TPCV valve 34 is closed, and then the CDCV valve 37 is opened in step S5, and the process returns to step S2.

If the determination in step S3 is YES, it means that the engine is in a predetermined light-load operation state. In this case, in step S6, a detection value of each sensor for detecting the engine operation state is input, and , Step S
In step 7, a reference pressure b serving as a negative pressure determination reference for determining whether a serious failure (large leak) has occurred in the evaporative fuel supply system is set based on the detected values of the water temperature and the atmospheric pressure. The reference pressure b is set to a negative pressure of about -200 mmAq to prevent erroneous failure determination due to insufficient negative pressure in the purge passage due to a tendency of the engine speed to decrease during high altitude traveling. The negative pressure is set to a smaller absolute value, that is, a higher pressure, as the atmospheric pressure is lower.

Next, step S8 and step S9
It is determined whether or not the determination condition of the abnormality diagnosis is satisfied.
That is, the engine speed Ne is determined whether a predetermined range Ne ₁ ~Ne ₂ at step S8, if the engine speed Ne is within a prescribed range, then the charging efficiency Ce is predetermined range Ce ₁ ~ in step S9 determining whether a ce _2, when the determination both of YES in determination and step S9 in step S8, the determination condition is satisfied, that it starts monitoring for large leakage determination, flow proceeds to step S10 Sets the monitor flag Fmo to 1. If either the determination in step S8 or the determination in step S9 is No, the determination condition is not satisfied, and the process proceeds to step S4.

If the monitor flag Fmo is set to 1 in step S10 because the determination condition is satisfied, then, in step S11, the internal pressure ftp (pressure sensor output) of the purge passage 30 detected by the FTP sensor 39 is detected. Value is within a predetermined range P _{A to} P _B (P _A is -190 m
is the value of mAq~-150mmAq, P _B is 0mmA
q. ), That is, P _A (-190 mm)
It is determined whether the negative pressure is equal to or less than (Aq to -150 mmAq). Then, the determination in step S11 is YES,
When ftp is a negative pressure below a predetermined value P _A is that it can be directly abnormality diagnosis, the process proceeds to step S16 described later.

If the determination in step S11 is No, f
If tp is a negative pressure larger than the predetermined value P _A , it is a high negative pressure state where abnormality diagnosis cannot be performed as it is, and then, in step S12, it is determined whether the pressure sensor output value ftp is in a high negative pressure state within a predetermined range. predetermined range P _C ~P _A (P
_C is, for example, -400 mmAq. ). Then, when it is a higher negative pressure side than the predetermined range P _C to P _A is to return to step S4, when the high negative pressure state of the predetermined range P _C to P _A, as once lowering process a negative pressure, step In S13, the CDCV valve 37 is kept open for a predetermined period, the TPCV valve 34 is opened in Step S14, and the purge valve 38 is fully closed in Step S15. And step S
Return to 6. During this time, the CDCV valve 37 is kept open, the TPCV valve 34 is opened, and the purge valve 38 is fully closed, whereby the introduction of the intake negative pressure is stopped, the atmospheric pressure is introduced, and the negative pressure in the purge passage 30 is reduced. Pressure drops. Then, when the determination in step S11 becomes YES, the process proceeds to step S16.

In step S16, the CDCV valve 37 is closed, then the purge valve 38 is opened in step S17, and T
The PCV valve 34 is opened. When the CDCV valve 37 is closed and the purge valve 38 and the TPCV valve 34 are opened, the negative pressure in the intake passage 5 is introduced into the purge passage 30, and the internal pressure of the purge passage 30 gradually decreases.

Thereafter, in step S19, the count value of the pressure reducing timer Tpgon is incremented by one, and then, in step S20, it is determined again whether or not the detected value of the throttle opening tvo is smaller than the reference opening a.

If the determination in step S20 is NO,
When the throttle opening tvo is larger than the reference opening a, the throttle opening delay time is counted by the timer Ttvd in step S21, and the count value of the timer Ttvd is calculated in step S22.
The timer Ttvd is compared with a preset reference time c of about one second to determine whether or not the time has expired. If the determination is YES and the time has not expired, the process returns to step S6 and returns to step S6. Repeat the operation.

If the determination in step S22 is NO and the timer Ttvd has timed out, it means that the state where the throttle opening tvo is larger than the reference opening a has been continued for a predetermined time. In this case, in order to prevent erroneous determination due to insufficient negative pressure in the purge passage 30, the timer Ttvd is determined in step S23.
Then, the process returns to step S4.

The determination in step S20 is YE
S, that is, if the detected value of the throttle opening tvo is smaller than the reference opening a, or if the detected value of the throttle opening tvo becomes smaller than the reference opening a within the reference time c, step S24 is performed. In, it is determined whether or not the internal pressure (pressure sensor output value) ftp of the purge passage 30 detected by the FTP sensor 39 is lower than the reference pressure b set in step S7. If NO in step S24, that is, if it is determined that ftp is higher than the reference pressure b, it is determined in step S25 whether the count value of the pressure reduction timer Tpgon is equal to or longer than a preset reference time d of about 30 seconds. If the determination is NO in step S25, the process returns to step S6 to repeat the above control operation.

If the determination in step S25 is YES,
If ftp is not lower than the reference pressure b even after the lapse of the reference time d, it means that there is a serious failure (large leak) in the evaporative fuel supply system, and a failure has occurred in step S26. A signal indicating the fact is output, and the control operation ends.

Then, the determination in step S24 is YES.
If ftp becomes lower than the reference pressure b, the negative pressure holding timer Tpgof for counting the diagnostic time e for measuring the degree of pressure increase in the purge passage 30 is reset to 0 in step S27, and S28
The maximum value ft of the pressure change amount stored in the storage means
Reset the stored value of brmax to zero.

Next, in step S29, the purge valve 38 is closed to close the purge passage 30. And
At the time when the reference time d has elapsed, the purge passage 30 detected by the FTP sensor 39 in step S30.
The internal pressure (output value of the pressure sensor) of the first detection pressure ftp
After storing as 1, the reference pressure P1 for determining the failure of the purge valve 38 in step S31 is set based on the detected values of the water temperature and the atmospheric pressure. The reference pressure P1 is, for example, −130 mmA in a normal operation state.
It is set to a value of about q.

Then, in step S32, the first
It is determined whether the detected pressure ftp1 is greater than the reference pressure P1. If the determination in step S25 is YES,
Control is performed by outputting a signal indicating that a moderate failure (leak) has occurred in the evaporative fuel supply system in step S33 because the state is a state in which a moderate failure (leakage) has occurred in the evaporative fuel supply system. End the operation.

If the result of the determination in step S32 is "NO", then in step S34, after inputting the detection values of the sensors for detecting the operating state of the engine, the flow proceeds to step S34.
In step 35, a reference value Pr of the degree of pressure increase, which is a reference for determining whether or not a minor failure (small leak) has occurred in the evaporative fuel supply system, is set based on the detected values of the water temperature and the atmospheric pressure. In S36, it is determined again whether the failure determination condition of the evaporative fuel supply system is satisfied. If the determination in step S36 is NO,
Proceed to step S4.

If the determination in step S36 is YES and it is determined that the failure determination condition of the evaporative fuel supply system is satisfied,
After adding the count value of the pressure reduction timer Tpgon by 1 in step S37, it is determined in step S38 whether or not the oil level fluctuation is large based on the detection signal of the remaining amount sensor 26. Then, the determination in step S38 is Y
In ES, when the fluctuation of the oil level is large, it means that it is not in a state where the failure determination of the evaporative fuel supply system should be executed.
Proceed to step S4.

If the determination in step S38 is NO, in step S39, a deviation of the current internal pressure (pressure sensor output value) ftp of the purge passage 30 detected by the FTP sensor 39 from the previous value is obtained. Accordingly, the pressure change amount ftpr at the time of the current control is calculated, and then, in step S40, the pressure change amount ftpr is compared with a stored value, and the larger one is compared with the maximum value ftp.
It is stored in the storage means as rmax.

Next, in step S41, the count value of the timer Tpgof is compared with a predetermined diagnosis time e of about 25 seconds to determine whether or not the timer Tpgof has timed out. If not, the process returns to step S34 to repeat the above control operation. Then, the determination in step S41 is YE
If it is determined in S that the diagnosis time e has elapsed, the internal pressure (pressure sensor output value) ftp of the purge passage 30 detected by the FTP sensor 39 is determined in step S42.
Is stored as the second detected pressure ftp2, and then, in step S43, the first detected pressure ftp1 is subtracted from the second detected pressure ftp2 to thereby increase the pressure increase degree (ftp2-ftp) of the purge passage 30 within the diagnosis time e.
Find 1).

Next, at step S44, the degree of pressure increase (ftp2) in the purge passage 30 within the diagnosis time e.
A value (k × | ftp2−ftp1 |) obtained by multiplying the absolute value of (−ftp1) by a preset coefficient K is set as the threshold A for determining the degree of shaking.

Then, in step S45, the maximum value ftprma of the pressure change amount obtained in step S40.
It is determined whether or not x is smaller than the threshold value A for determining the degree of fluctuation. If the determination is NO, the fluctuation of the oil level of the fuel in the fuel tank 20 is large, and the vaporization of the fuel is promoted. Therefore, if the internal pressure of the purge passage 30 is in a state where it is likely to increase greatly in a short time, the process returns to step S4 without performing the failure determination.

If the determination in step S45 is YES,
When the fluctuation of the oil level of the fuel in the fuel tank 20 is small, it is determined in step S46 whether or not the absolute value | ftp2−ftp1 | of the degree of pressure increase is smaller than the second reference value Pr.

If the determination in step S46 is NO,
Absolute value of the degree of pressure increase in purge passage 30 | ftp2-f
If tp1 | is equal to or greater than the second reference value Pr, step S4
At 7, a signal indicating that a failure such as a crack formed in the purge passage 30 has occurred is output.

The determination in step S46 is YES.
Is the absolute value of the degree of pressure rise in the purge passage 30 | ftp2
If -ftp1 | is smaller than the second reference value Pr, it means that it is normal, and the CVD in step S48 is performed.
The V valve 37 is opened, and then, in step S49, TP
The CV valve 34 is closed. Then, in step S50, the monitor flag Fmo is reset to 0, and the control process ends.

FIGS. 8 and 9 are flowcharts for executing the process of diagnosing the abnormality of the FTP sensor 39 when the sensor abnormality is determined based on the monitor value during the period a 'shown in FIG. And step S101
In step S102, it is determined whether or not the engine has been operated. In step S102, the maximum value ftpmax and the minimum value ftpmin of the pressure sensor output value are reset to 0.

Then, in step S103, FT
The sensor output value ftp of the P sensor 39 is input. Then, in steps S104 to S107, the maximum value ftpmax and the minimum value ftpmin of the pressure sensor output value are obtained. That is, in step S103, the current pressure sensor output value ftp is stored in the maximum value f
It is determined whether or not it is larger than tpmax, and the determination is YES.
If the current pressure sensor output value ftp is larger than the previous maximum value ftpmax, the current pressure sensor output value ftp is set to the new maximum value ftp in step S105.
After storing as pmax, the process proceeds to step S106,
If the determination is NO and the current pressure sensor output value ftp is equal to or less than the maximum value ftpmax up to then, step S10
The process skips Step 5 and proceeds directly to Step S106. Then, in step S106, it is determined whether or not the current pressure sensor output value ftp is smaller than the previous minimum value ftpmin. If the determination is YES and the current pressure sensor output value ftp is smaller than the previous minimum value ftpmin, Is stored in step S107 as the new sensor output value ftp as a new minimum value ftpmin, and then proceeds to step S108. If the determination is NO and the current pressure sensor output value ftp is equal to or greater than the previous minimum value ftpmin, , Skips step S107 and proceeds directly to skip S108.

In step S108, it is determined whether the setting of the monitor flag Fmo set in steps S10 and S50 in the flowcharts of FIGS. 3 to 7 is 0 (zero). If the determination is YES and the setting of the monitor flag Fmo is 0, it means that the monitoring start point of the large leak determination has not been reached, and the process returns to step S103.

Then, the determination in step S108 is NO.
If it is determined that the monitor flag Fmo is 1, the process proceeds to step S109 where the previous monitor flag Fm
It is determined whether or not o is 0. If the determination is NO and the previous time is also 1, the process returns to step S103.

Then, the determination in step S109 is YES.
When the previous monitor flag Fmo was 0, it means that the monitoring start point of the large leak determination, that is, the start point of the period for changing the pressure in the path (for example, the period of a in FIG. 2) has been entered. In step S110, it is determined whether or not the degree of change of the pressure sensor output value, that is, the difference between the stored maximum value ftpmax and the minimum value ftpmin of the pressure sensor output value is equal to or greater than a predetermined value (predetermined degree) S. If the degree of change is equal to or greater than the predetermined degree S, the diagnosis is terminated because there is no sticking failure in the FTP sensor 39. If the degree of change is smaller than the predetermined degree S, step S11 is performed.
In step 1, it is determined that the FTP sensor 39 has an abnormality due to a sticking failure, and this is stored. Step S
At 110, the current ftp signal ftp1 and ftpma
x difference (ftp1−ftpmax) and ftpmin
It may be determined whether or not the difference (ftp1-ftpmin) is equal to or greater than a predetermined value, and if both are smaller than the predetermined value, the process may proceed to step S111 to determine a failure.

In the case where the sensor abnormality is determined based on the monitor value during the period b 'shown in FIG.
The flowchart for executing the process of diagnosing abnormality of the P sensor 39 corresponds to the flowchart shown in FIGS. 8 and 9 in which steps S108 to 111 are changed to steps S208 to 212 shown in FIG. . In this case, the maximum value ftpmax and the minimum value ftp of the pressure sensor output values are determined in steps S104 to S107.
After obtaining min, the monitor flag F is set in step S208.
It is determined whether or not the setting of mo is 1; if the determination is NO and the monitor flag Fmo is 0, it means that the monitoring start point of the large leak determination has not been reached, and step S
It returns to 103.

Then, the determination in step S208 is YES
When the monitor flag Fmo is 1, the monitoring start point of the large leak determination is entered, and the period indicated by b in FIG. 2 is entered. In step S209, the timer Tmo for measuring the time until the sensor abnormality determination is performed. Is started, and it is determined whether or not the timer Tmo has reached the predetermined value Tmoo in step S210. If the timer Tmo has not reached the predetermined value Tmoo, the process returns to step S103 to return to the maximum value ftpmax and the minimum value ftpmi.
The update of n and the addition of the timer Tmo are repeated. Then, when the timer Tmo reaches the predetermined value Tmoo, step S2
In step 10, it is determined whether the degree of change of the pressure sensor output value, that is, the difference between the stored maximum value ftpmax and the minimum value ftpmin of the pressure sensor output value is equal to or greater than a predetermined value (predetermined degree) S. If the degree of change is equal to or greater than the predetermined degree S, the diagnosis is terminated because there is no sticking failure in the FTP sensor 39. If the degree of change is smaller than the predetermined degree S, the failure in the FTP sensor 39 is determined in step S212. It is determined that an abnormality has occurred, and that is stored.

FIG. 11 is a flowchart of the purge control, which starts at predetermined time intervals and inputs various information in step S301. Then, in a step S302, it is determined whether or not a predetermined period has elapsed since the start of the engine.
When it is determined that the predetermined period has elapsed after the start, the process proceeds to step S303.
In step S309, the opening degree of the purge valve 38 is set to fully closed.
Drive.

In step S302, the determination is N.
If it is determined in O that a predetermined period has elapsed after the engine is started, the basic opening of the purge valve 38 is set in step S304, a correction value is set in step S305, and the final opening is set in step S306.

In step S307, it is determined whether the purge system is being monitored, that is, whether the monitor flag Fmo is 1. If the determination is YES and the purge system is being monitored, the purge valve by the purge system monitor is determined in step S308. After inputting the set opening of 38, the process proceeds to step S309, and the purge valve 38 is driven based on the set opening by the monitor. When the determination in step S308 is NO and the purge system is not being monitored,
Step S308 is skipped and the process proceeds to step S309, and the purge valve 3 is opened at the opening set in step S306.
8 is driven.

[0069]

According to the present invention, even when the path abnormality diagnosis is not executed as it is in a high negative pressure state in the evaporative fuel supply path, the abnormality diagnosis of the pressure sensor disposed in the evaporative fuel supply path is performed. Can be executed, and an abnormal state due to the sticking of the pressure sensor can be determined quickly and accurately.

[Brief description of the drawings]

FIG. 1 is a system diagram of an engine according to an embodiment of the present invention.

FIG. 2 is a time chart illustrating a process of diagnosing an abnormality in a fuel vapor supply path and a pressure sensor disposed in the path.

FIG. 3 is a part of a flowchart of a process of evaporative fuel supply system abnormality diagnosis.

FIG. 4 is a part of a flowchart of processing for evaporative fuel supply system abnormality diagnosis.

FIG. 5 is a part of a flowchart of a process of evaporative fuel supply system abnormality diagnosis.

FIG. 6 is a part of a flowchart of a process of evaporative fuel supply system abnormality diagnosis.

FIG. 7 is a part of a flowchart of processing for evaporative fuel supply system abnormality diagnosis.

FIG. 8 is a part of a flowchart of a sensor abnormality diagnosis process;

FIG. 9 is a part of a flowchart of a sensor abnormality diagnosis process;

FIG. 10 is a part of a flowchart of a sensor abnormality diagnosis process according to another example.

FIG. 11 is a flowchart of a purge control.

[Explanation of symbols]

 7 Air flow sensor 17 Crank angle sensor 19 Water temperature sensor 20 Fuel tank 34 PCTV valve 37 CDCV valve 38 Purge valve 39 FTP sensor (pressure sensor) 40 ECU (Engine control unit)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Haebaru 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda F-term (reference) 3G084 BA06 BA11 BA16 BA27 BA33 DA27 DA30 EA05 EA07 EA11 EB06 EB22 EC06 FA00 FA01 FA07 FA10 FA20 FA29 FA33 FA38

Claims (6)

[Claims] 1. A pressure sensor disposed in an evaporative fuel supply path for supplying evaporative fuel generated in a fuel tank to an intake passage of an engine and detecting a pressure in the evaporative fuel supply path, and a predetermined determination condition is satisfied. A pressure adjusting means for adjusting the introduction of the intake negative pressure and the introduction of the atmospheric pressure into the evaporative fuel supply passage so as to change the pressure in the evaporative fuel passage for a predetermined period of time; An abnormality diagnosis device for a pressure sensor, comprising: a sensor abnormality determination unit configured to determine abnormality of the pressure sensor based on a degree of change in a pressure sensor output value later. When the detected value of the pressure in the passage at the time of establishment is a negative pressure that is larger than a predetermined value, the introduction of the intake negative pressure and the atmospheric pressure so that the pressure in the passage changes in the negative pressure decreasing direction in advance. Adjusting the introduction of pressure, the sensor abnormality determination means, when the detected value of the pressure in the path when the predetermined condition is satisfied is a negative pressure larger than a predetermined value, by the pressure adjustment means in the path When the degree of change in the output value of the pressure sensor after the period in which the introduction of the intake negative pressure and the introduction of the atmospheric pressure are adjusted so that the pressure in the path changes in the negative pressure decreasing direction or after the period is smaller than a predetermined degree, An apparatus for diagnosing abnormality of a pressure sensor, wherein the apparatus determines that the pressure sensor is abnormal. 2. The apparatus according to claim 1, wherein the sensor abnormality determination unit is configured to adjust the introduction of the intake negative pressure and the introduction of the atmospheric pressure such that the pressure in the path changes in a negative pressure decreasing direction by the pressure adjustment means in the path. 2. The abnormality diagnostic device for a pressure sensor according to claim 1, wherein the abnormality determination of the sensor is performed based on the degree of change of the output value of the pressure sensor. 3. The in-path pressure adjusting means, when the detected value of the in-path pressure when the predetermined condition is satisfied is a negative pressure equal to or less than the predetermined value, or when the predetermined condition is satisfied. By adjusting the introduction of the intake negative pressure and the introduction of the atmospheric pressure such that the detected value of the pressure in the path is a negative pressure larger than the predetermined value, and the pressure in the path temporarily changes in the negative pressure decreasing direction, When the detected value of the pressure in the path becomes a negative pressure equal to or less than the predetermined value, the introduction and introduction of the intake negative pressure so that the pressure in the path changes in a negative pressure increasing direction to a negative pressure equal to or more than a second predetermined value. After adjusting the introduction of the atmospheric pressure, the introduction of the intake negative pressure and the introduction of the atmospheric pressure are adjusted so as to maintain the negative pressure of the pressure in the passage for a predetermined period. Of the pressure in the path when the predetermined condition is satisfied When the output value is a negative pressure equal to or less than the predetermined value, adjustment for adjusting the introduction of the intake negative pressure and the introduction of the atmospheric pressure by the in-path pressure adjusting means so that the in-path pressure changes in the negative pressure increasing direction. From the start of the operation,
Based on the degree of change of the output value of the pressure sensor during a period until the end of the adjustment operation for adjusting the introduction of the intake negative pressure and the introduction of the atmospheric pressure so as to maintain the negative pressure of the pressure in the path for a predetermined period, a sensor abnormality is detected. When the determination is made, and the detected value of the pressure in the path when the predetermined condition is satisfied is a negative pressure larger than the predetermined value, the pressure in the path temporarily changes in the negative pressure decreasing direction by the pressure control means in the path. From the start of the adjusting operation for adjusting the introduction of the intake negative pressure and the introduction of the atmospheric pressure, the pressure in the path is changed in a negative pressure increasing direction, and then the negative pressure of the path pressure is maintained for a predetermined period. 2. A sensor abnormality determination is performed based on a degree of change in the output value of the pressure sensor during a period until an adjustment operation for adjusting the introduction of the intake negative pressure and the introduction of the atmospheric pressure is completed. Abnormality diagnosis apparatus for a pressure sensor mounting. 4. The method according to claim 1, wherein the path pressure adjusting means changes the path pressure in a negative pressure increasing direction from a state in which the detected value of the path pressure is a negative pressure equal to or less than the predetermined value, and thereafter holds the pressure. 4. The pressure according to claim 3, wherein, based on a degree of change in the output value of the pressure sensor during a period of adjusting the introduction of the intake negative pressure and the introduction of the atmospheric pressure, the sensor abnormality determination and the abnormality determination of the evaporative fuel supply path are performed. Abnormal diagnostic device for sensors. 5. The pressure sensor abnormality diagnosis apparatus according to claim 2, wherein the monitoring of the output value of the pressure sensor for determining the abnormality of the sensor is started immediately after the engine is started. 6. A pressure sensor disposed in an evaporative fuel supply path for supplying evaporative fuel generated in the fuel tank to an intake passage of the engine and detecting a pressure in the evaporative fuel supply path; When the pressure in the evaporative fuel supply path is changed for a predetermined period when the pressure in the evaporative fuel path is changed, the pressure control means in the path adjusts the introduction of the intake negative pressure and the atmospheric pressure into the evaporative fuel supply path; A path abnormality determining unit that determines abnormality of the evaporative fuel supply path based on a degree of change in the output value of the pressure sensor after a period has elapsed. When the detected value of the pressure in the path at the time when the predetermined condition is satisfied is a negative pressure larger than a predetermined value, the intake air is preliminarily changed in the negative pressure decreasing direction. And adjusting the introduction of the negative pressure and the introduction of the atmospheric pressure, wherein the path abnormality determination means is configured to detect when the detected value of the pressure in the path when the predetermined condition is satisfied is a negative pressure larger than the predetermined value. After the introduction of the intake negative pressure and the introduction of the atmospheric pressure are adjusted so that the pressure in the path changes in the negative pressure decreasing direction by the pressure adjustment means in the path, a path abnormality determination is performed in the predetermined period. An abnormality diagnosis device for an evaporative fuel supply path characterized by the following.