JP3045892B2 - Pressure sensor abnormality detection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting an abnormality of a pressure sensor used in an internal combustion engine, and more particularly, to an abnormality judgment of a pressure sensor in a wide operating range and a disconnection of a communication pipe of the pressure sensor. The present invention relates to a pressure sensor abnormality detection device for an internal combustion engine that can be used.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Publication No.
In a fuel injection system of a speed density system called a D-jetro system as referred to in Japanese Patent Application Laid-Open Publication No. H07-115, a pressure sensor for detecting an intake pipe pressure, a rotational speed sensor for detecting an engine rotational speed, and the like are used. The fuel injection amount is determined by a map calculation based on the intake pipe pressure and the engine speed, and the air-fuel mixture in the intake pipe is controlled to the stoichiometric air-fuel ratio. Further, the pressure sensor is not limited to this, and the pressure sensor can be used for various other applications, and therefore, it is necessary to constantly monitor the operation state of the pressure sensor.

FIG. 2 is a block diagram showing a general internal combustion engine control device including a pressure sensor. In the figure, 1 is an internal combustion engine composed of, for example, a four-cycle engine, and 2 is an internal combustion engine
A throttle valve (hereinafter simply referred to as "throttle") for controlling the amount of intake air by opening and closing the intake pipe 2 in conjunction with an accelerator (not shown);
4 is a throttle opening sensor for detecting the opening α of the throttle 3 corresponding to the intake air amount, 5 is an air cleaner provided upstream of the intake pipe 2 to purify intake air, and 6 is an intake pipe 2
, An injector for injecting fuel, 7 a pressure sensor for detecting a pressure P in the intake pipe 2, a vehicle speed sensor 8 for detecting a running speed (vehicle speed) V of the vehicle, and 9 a rotation of the internal combustion engine 1. This is a rotation speed sensor that detects the number Ne.

The pressure sensor 7 has a positive terminal to which a voltage of 5 V is applied, a ground terminal to which a voltage of 0 V is applied,
An output terminal for generating a voltage signal in a range from 0 V (corresponding to vacuum pressure) to 4 V (corresponding to atmospheric pressure) as a pressure detection value P; It becomes 5V when short-circuited to the positive terminal, and becomes 0V when short-circuited to the ground terminal.

Reference numeral 10 denotes an electronic control unit (hereinafter, referred to as an ECU) including a microcomputer, which includes a throttle opening α, a pressure detection value P, and a vehicle speed V from the sensors 4 and 7 to 9.
And an operating state signal D from the rotation speed Ne and other various sensors (not shown) to generate a driving signal J and the like for the injector 6.

[0006] The ECU 10 includes a rotation determining means for determining whether or not the rotational speed Ne is equal to or less than a predetermined value, and a pressure sensor 7 when the detected pressure value P is equal to or less than the predetermined value when the rotational speed Ne is equal to or less than the predetermined value. Abnormality judgment means for judging abnormality of the above.
Further, another abnormality determining means for determining a short circuit failure of the pressure sensor 7 when the pressure detection value P indicates 5 V or 0 V is included. Even when the output terminal of the pressure sensor 7 is disconnected, the pressure detection value P is maintained at 5 V. Is determined as failure.

FIG. 3 is a characteristic diagram showing a detected pressure value P (corresponding to the absolute pressure in the intake pipe 2) that can be taken in accordance with the throttle opening α and the engine speed Ne. This corresponds to the lower limit that can normally be taken (intake pipe pressure of about 100 mmHg), and Pa (about 4 V) is the atmospheric pressure (760
mmHg).

The characteristic curve (α = 0%) of the detected pressure value P that can be obtained when the throttle opening α is 0% (fully closed) with respect to the change in the rotation speed Ne is that the accelerator is not depressed at all. Nevertheless, this is a curve obtained when the vehicle is forcibly accelerated on a downhill or the like. Also, the throttle opening α is 0%
Characteristic curve of pressure detection value P that can be taken in the case of (α = 0%)
And a characteristic curve (α = 100%) of the detected pressure value P that can be obtained when the throttle opening α is 100% (fully open). This is a region where the obtained pressure detection value P can be obtained.

As shown in FIG. 3, when the throttle opening α is small, the detected pressure value P sharply decreases with an increase in the rotation speed Ne due to the operation of the vacuum pump of the internal combustion engine 1, and the throttle opening α increases. For example, since the amount of intake air to the internal combustion engine 1 increases, the detected pressure value P indicates a voltage value substantially corresponding to the atmospheric pressure even if the rotation speed Ne increases.

Next, the operation of the conventional pressure sensor abnormality detecting device for an internal combustion engine will be described with reference to FIGS. During normal operation, the internal combustion engine 1 mounted on the automobile sucks in the air purified by the air cleaner 5 through the intake pipe 2. At this time, the injector 6 injects fuel in response to the drive signal J, and supplies a combustion air-fuel mixture to the internal combustion engine 1. The throttle 3 opens and closes the intake pipe 2 in response to an accelerator operated by the driver, and determines an intake air amount corresponding to the output torque of the internal combustion engine 1.

At this time, the pressure sensor 7 converts the absolute pressure in the intake pipe 2 into a voltage signal (about 0.5 V to 4 V),
The detected pressure value P is input to the ECU 10. The throttle opening sensor 4, the vehicle speed sensor 8 and the rotation sensor 9
The throttle opening α, the vehicle speed V, and the rotation speed Ne are respectively detected and input to the ECU 10, and various other sensors input various operating state signals D to the ECU 10.

When the rotational speed Ne is equal to or less than a predetermined value (for example, 400 rpm), the ECU 10 indicates that the detected pressure value P is equal to or less than a predetermined value (for example, about 1 V corresponding to an absolute pressure of 200 mmHg) in FIG. When this state continues for a predetermined time (for example, 2 seconds) or more, it is determined that the pressure sensor 7 is abnormal.

At this time, the rotational speed Ne and the detected pressure value P
Is set to a value that cannot be indicated simultaneously when the internal combustion engine 1 is normal, as described in the above-mentioned Japanese Patent Publication No. 1-41824. In the region, since the rotation speed Ne during normal idling is about 700 rpm, the rotation speed Ne during startup is Ne.
Exist only for a short time in the transitional period before rising to the idling speed.

In a system for detecting the pressure of the intake pipe by connecting the intake pipe 2 and the pressure sensor 7 with a communication pipe (rubber hose), when the rubber hose comes off from the intake pipe 2 or the pressure sensor 7, the pressure is detected. Although the value P indicates the voltage value Pa corresponding to the atmospheric pressure, the abnormality determination means and another abnormality determination means in the ECU 10 as described above cannot determine a failure.

[0015]

As described above, in the conventional internal combustion engine pressure sensor abnormality detection apparatus, the pressure detection value P continuously shows a value equal to or less than the predetermined value for a predetermined time in the operating region where the rotational speed Ne is low. Since the abnormality of the pressure sensor 7 is detected at the time, the operating speed N
There is a problem that there is only a few chances at the time of the rise transition of e, and it is not possible to detect a disconnection of the communication pipe between the intake pipe 2 and the pressure sensor 7 and the like.

The first to third aspects of the present invention have been made to solve the above-described problems, and a pressure sensor for an internal combustion engine capable of determining a failure of a pressure sensor in a wide operating range. An object is to obtain an abnormality detection device.

[0017] Claims 4 and 5 of the present invention are:
It is an object of the present invention to provide a pressure sensor abnormality detection device for an internal combustion engine capable of determining a failure of a pressure sensor in a wide operating range and determining a disconnection of a communication pipe between an intake pipe and a pressure sensor.

[0018]

According to a first aspect of the present invention, there is provided a pressure sensor abnormality detecting device for an internal combustion engine, comprising: a pressure sensor for detecting an intake pipe pressure of the internal combustion engine; a vehicle speed sensor for detecting a vehicle speed; determining a vehicle speed determining means determines whether a predetermined vehicle speed or less, when the vehicle speed is less than a predetermined vehicle speed, the detected pressure value from the pressure sensor, whether or lower than the lower limit which can not indicate a predetermined vehicle speed following speed The vehicle includes a lower limit value determining unit and an abnormality determining unit that determines that the pressure sensor is abnormal if the detected pressure value is equal to or lower than the lower limit value when the vehicle speed is equal to or lower than the predetermined vehicle speed.

[0019]

[0020]

[0021]

[0022]

[0023]

According to a first aspect of the present invention, a failure determination operation region is set over a wide range according to a vehicle speed condition equal to or lower than a predetermined vehicle speed.
An abnormality of the pressure sensor indicating a detected pressure value equal to or lower than the lower limit value is determined.

[0024]

[0025]

[0026]

[0027]

[0028]

【Example】

Embodiment 1 FIG. Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing the operation of the abnormality determining means and its related means in Embodiment 1 of the present invention.
This is a process executed by the ECU every predetermined crank angle or every predetermined time. The overall configuration of the internal combustion engine to which the first embodiment of the present invention is applied is as shown in FIG.
The only difference lies in the abnormality determination means in the ECU 10 and the means related thereto. The basic calculation control operation and the like of other units including another abnormality determination unit in the ECU 10 are the same as those described above.

In this case, the ECU 10 determines whether the vehicle speed V is equal to or lower than a predetermined vehicle speed Vo, and determines whether the throttle opening α is equal to or lower than a predetermined lower limit opening αo. Throttle opening determination means for determining whether or not the throttle opening α is equal to or greater than a predetermined opening αk;
Is equal to or lower than a predetermined vehicle speed Vo or the throttle opening α is a predetermined opening α
When more than k, the pressure detection value P from the pressure sensor, where
A lower limit pressure determining means for determining whether the vehicle speed is equal to or lower than a lower limit value PL which cannot be indicated at a vehicle speed lower than the constant vehicle speed Vo, and a pressure detection value when the vehicle speed V is lower than a predetermined vehicle speed Vo or the throttle opening α is higher than a predetermined opening αk. Abnormality determination means for determining that the pressure sensor 7 is abnormal if P is equal to or less than the lower limit value PL; rotation number determination means for determining whether the rotation number Ne is equal to or greater than a predetermined rotation number Neo; When α is equal to or less than the lower limit opening αo and the rotation speed Ne is equal to or greater than the predetermined rotation speed Neo, an upper limit value determination is performed to determine whether or not the pressure detection value P is equal to or greater than an upper limit PH which cannot be indicated at a vehicle speed equal to or less than the predetermined vehicle speed Vo. Means,
When the throttle opening α is equal to or less than the lower limit opening αo and the rotational speed Ne is equal to or greater than the predetermined rotational speed Neo, the pressure detection value P becomes equal to the upper limit value P.
An abnormality determination unit that determines that the pressure sensor 7 is abnormal if H or more, and a normality determination unit that determines that the pressure sensor 7 is normal if the detected pressure value P is larger than the lower limit value PL.

In FIG. 3, the lower limit value PL is a reference value for failure determination, and the detected pressure value P of the pressure sensor 7 is lower than the lower limit value PL.
If it is below, it is basically determined to be a failure. However, as described above, even if the pressure sensor 7 is normal, the pressure detection value P becomes equal to or less than the lower limit value PL (P shown in FIG. 3).
(A hatched area below L), and it is not possible to determine that the pressure sensor 7 is faulty only because P ≦ PL is satisfied.

Therefore, in the embodiment of the present invention, when the vehicle is almost stopped (for example, 5 km / h), the detected pressure value P is compared with the lower limit value PL to determine whether the pressure sensor 7 has failed. Has been determined. This is because the shaded area below PL in FIG. 3 indicates a case where the vehicle is forcibly accelerated on a downhill or the like, and if the vehicle is almost stopped, the pressure detection value P may exist in this area. Because there is no.

In the embodiment of the present invention, if the throttle opening α is equal to or more than a predetermined opening (for example, about 20%), the detected pressure value P is compared with the lower limit value PL to compare the pressure sensor value with the lower limit value PL. Failure has been determined. Because in Figure 3,
An infinite characteristic curve corresponding to each throttle opening α (0% to 100%) exists between the characteristic curve of α = 0% and the characteristic curve of α = 100%. This is because the characteristic curve does not fall below the lower limit value PL and a failure of the pressure sensor 7 is not erroneously detected.

Further, in the embodiment of the present invention, if the throttle opening α is substantially fully closed and the internal combustion engine 1 is not in the engine stall state, the detected pressure value P and the upper limit value (failure determination reference value) PH Are compared to determine the failure of the pressure sensor 7. The reason is that if the throttle opening α is almost fully closed and the internal combustion engine 1 is not in the engine stall state, a negative pressure is generated in the intake pipe 2 and the detected pressure value P becomes the upper limit value P
This is because it does not exceed H. By performing such a determination, it is also possible to detect a failure such as disconnection of the communication pipe.

Next, referring to FIGS. 2 and 3, FIG.
The operation of the first embodiment of the present invention shown in FIG.
First, the ECU 10 reads the throttle opening α, the vehicle speed V, and the rotation speed Ne, and outputs the output signal of the pressure sensor 7 to A.
The D-conversion is performed and the detected pressure value P is read (step S1).

Subsequently, the lower limit opening determination means in the ECU 10 determines whether or not the throttle opening α is equal to or less than a predetermined lower limit opening αo (about several% corresponding to a substantially fully closed state of the throttle 3) ( Step S2). If it is determined that the throttle 3 is not fully closed and α> αo (that is, NO),
Subsequently, the throttle opening determination unit determines whether the throttle opening α is equal to or greater than a predetermined opening αk (for example, about 20%) (step S3).

If it is determined in step S3 that α ≧ αk (that is, YES), the flow proceeds to step S8, and a failure determination is performed. If it is determined that α <αk (that is, NO), the vehicle speed V is subsequently set to the predetermined vehicle speed Vo (approximately 5 km / h corresponding to a vehicle stopped state) by the vehicle speed determination means.
It is determined whether or not it is below (step S4).

If it is determined in step S4 that V≤Vo (that is, YES), the flow proceeds to step S8, and a failure determination is performed. Also, when the vehicle is not stopped, V> Vo
If the determination is NO, the lower limit determining unit determines whether the detected pressure value P is equal to or less than a predetermined lower limit PL (step S5).

If it is determined in step S5 that P> PL (that is, NO), the normality determining means clears a failure detection flag indicating an abnormality of the pressure sensor 7 to 0 (step S6), and then resets the timer counter. A predetermined value M for down-counting is set in CT (step S7), and the routine of FIG. 1 ends.

On the other hand, if it is determined in step S5 that P.ltoreq.PL (that is, YES), the process proceeds to step S7 while keeping the failure detection flag at the previous time, and the timer counter C
T is set to a predetermined value M, and the process ends. Because, for example,
When the vehicle is accelerating on a downhill with a small throttle opening α, the detected pressure value P can be equal to or lower than the lower limit PL as shown by the characteristic curve of α = 0% in FIG.
This is because it is not possible to determine whether or not is a failure.

If the result of the determination in step S3 or S4 is YES, that is, if the throttle opening α is equal to the predetermined opening αk
(Α ≧ αk) or the vehicle is almost stopped (V ≦ V
If o), the lower limit pressure determining means determines that the pressure detection value P is at a vehicle speed equal to or lower than the predetermined vehicle speed Vo in this state.
Determines whether the following (0.5V corresponding to 100mmHg absolute pressure) the lower limit value PL which can not illustrated Te (step S
8).

If α ≧ αk, the detected pressure value P approaches the atmospheric pressure equivalent value Pa (about 4 V). Therefore, as can be understood from the characteristic curve of FIG. 3, the lower limit value PL (0.
5V) is a value that cannot be detected by the pressure detection value P.

Similarly, if V ≦ Vo (for example, in a state of waiting for a signal), the engine speed is close to the idling speed (about 700 rpm), so that the lower limit can be understood from the characteristic curve of FIG. The value PL (0.5 V) is a value that cannot be detected by the pressure detection value P.

Further, even if the rotational speed increases due to an air blow or the like in the state of waiting for a signal, the characteristic curve of FIG. 3 shifts upward in accordance with the throttle opening α. P does not fall below the lower limit PL.

In the failure determination step S8 when V ≦ Vo or α ≧ αk, P> PL (ie, N
If the determination is O), the normality determining means determines the pressure sensor 7
Is considered normal, the process proceeds to step S6, and the failure detection flag is cleared.

On the other hand, in step S8, P ≦ PL
(Ie, if YES), the timer counter CT
Is determined to be decremented to 0 (step S9). If CT = 0 (that is, YES), the abnormality determination means determines that the pressure sensor 7 is abnormal, and sets the failure detection flag to 1 Is set (step S10), and the routine of FIG. 1 ends.

If it is determined in step S9 that CT> 0 (that is, NO), the timer counter CT is decremented (step S11), the routine in FIG. 1 is terminated, and the lower limit is set until CT = 0. The determination step S8 is repeated. The predetermined value M set in the timer counter CT in step S7 reaches 0 when the abnormal state continues for about 4 seconds after the lower limit abnormal value of the pressure detection value P is first determined in step S8. It is determined to such a value.

On the other hand, if it is determined in step S2 that the throttle 3 is almost fully closed and α ≦ αo (that is, YES), the rotation speed Ne is then set to a predetermined rotation speed by the rotation speed determination means. It is determined whether or not the number is equal to or greater than several Neo (about 100 rpm indicating that the internal combustion engine 1 is not running) (step S12).

If the internal combustion engine 1 is in the engine stall state and it is determined that Ne <Neo (that is, NO), the process proceeds to step S3, and the above-described processing steps are executed.

The upper limit value PH serving as a criterion at this time is:
Since the throttle opening α is set to a value that can be taken by the pressure detection value P when the throttle is fully opened, and changes along a characteristic curve of α = 100% in FIG. 3, it is given by, for example, a map calculation corresponding to the rotation speed Ne. Can be

If it is determined in step S13 that the throttle opening α is fully closed and the internal combustion engine 1 is not stalled (α ≦ αo and Ne ≧ Neo), then it is determined that P <PH (that is, NO). , And proceeds to step S3 to execute the above-described processing steps.

In step S13, P ≧ PH
If the determination is YES (ie, YES), the process proceeds to step S9. As described above, when the abnormal state continues for about 4 seconds, the abnormality determination unit determines that the pressure sensor 7 is abnormal, and in step S10, a failure occurs. The detection flag is set.

As described above, if the pressure sensor 7 is normal, attention can be paid to the point that P ≦ PL does not hold under the following conditions (1) or (2), and an abnormality can be determined in step S8. . That is, (1) when the accelerator is depressed so that α ≧ αk, and the characteristic curve of the detected pressure value P shown in FIG. 3 becomes sufficiently larger than the lower limit value PL;
That is, when the vehicle is almost stopped.

If the pressure sensor 7 is normal, the detected pressure value P is equal to the atmospheric pressure equivalent value P under any environmental conditions.
It is noted that when the throttle is fully closed when a sufficient negative pressure is generated in the intake pipe 2, α = 1
By using the upper limit value PH matched to the value on the characteristic curve of 00%, not only the upper limit abnormality determination of the detected pressure value P but also a failure such as disconnection of a rubber hose pipe connecting the intake pipe 2 and the pressure sensor 7 is caused. Can be determined.

Embodiment 2 FIG. In the first embodiment, the timer processing steps S7, S9, and S10 are used. However, the timer processing may be omitted, and the process may immediately proceed from the lower limit determination step S8 or the upper limit determination step S13 to the abnormality determination step S10.

Embodiment 3 FIG. When the determination results in the determination steps S8 and S13 for the lower limit and the upper limit are YES, the process proceeds to the same abnormality determination step S10, in which the failure detection flag is set. May be set. In this case, for example, different alarms or the like can be driven according to the type of the failure detection flag, and prompt measures can be taken.

Embodiment 4 FIG. If the result of the determination in the throttle opening determination step S3 or the vehicle speed determination step S4 is YES
In the case of (1), the lower limit determination step S8 is performed, but the lower limit determination step S8 may be performed based on only the determination result of one of the determination steps S3 or S4, and the failure determination area is larger than that of the conventional device. Needless to say.

Embodiment 5 FIG. Also, the lower limit determination processing step S3
The upper limit determination processing steps S2, S12, and 13 when the throttle is fully closed are executed in parallel with S10 to S10. However, even when only the upper limit determination processing steps S2, S7, and S9 to S13 are performed, the same operation is performed for the upper limit determination. It is needless to say that not only the effect is obtained, but also the failure determination area is expanded as compared with the conventional device.

Embodiment 6 FIG. Further, an upper limit determination step S13
In FIG. 3, α = 10
Although the value on the characteristic curve of 0% is used, it may be set to a predetermined value of about 3.5 V that can be distinguished from the atmospheric pressure equivalent value.

[0059]

As described above, according to the first aspect of the present invention, a pressure sensor for detecting an intake pipe pressure of an internal combustion engine, a vehicle speed sensor for detecting a vehicle speed, and determining whether or not the vehicle speed is equal to or lower than a predetermined vehicle speed. a vehicle speed determining means for, when the vehicle speed is less than a predetermined vehicle speed, the detected pressure value from the pressure sensor, the predetermined vehicle speed following the car
Abnormality determining means for determining the lower limit value determining means for determining whether or lower than the lower limit which can not illustrated in gear, the vehicle speed is a pressure sensor abnormality is equal to or lower than the lower value pressure detection value when more than a predetermined vehicle speed The failure determination operation region is set according to a vehicle speed condition equal to or lower than a predetermined vehicle speed, so that there is no erroneous determination at the time of a fully closed downhill where the intake pipe negative pressure is large and the pressure detection value is small. This has the effect of providing a pressure sensor abnormality detection device for an internal combustion engine that can determine a failure of a pressure sensor having the following detected pressure value in a wide operating range.

[0060]

[0061]

[0062]

[0063]

[Brief description of the drawings]

FIG. 1 is a flowchart showing the operation of Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram showing a general internal combustion engine control device.

FIG. 3 is a characteristic diagram showing detected pressure values that can be taken according to a throttle opening and a rotation speed in a general internal combustion engine.

[Explanation of symbols]

 Reference Signs List 1 internal combustion engine 2 intake pipe 4 throttle opening sensor 7 pressure sensor 8 vehicle speed sensor 9 rotation speed sensor Ne rotation speed Neo predetermined rotation speed P pressure detection value PH upper limit value PL lower limit value V vehicle speed Vo predetermined vehicle speed α throttle opening αo lower limit opening Degree αk Predetermined opening S2 Lower limit opening determining step S3 Throttle opening determining step S4 Vehicle speed determining step S8 Lower limit determining step S10 Abnormality determining step S12 Revolution determining step S13 Upper limit determining step

Claims (1)

(57) [Claims] 1. A pressure sensor for detecting an intake pipe pressure of an internal combustion engine, a vehicle speed sensor for detecting a vehicle speed, a vehicle speed determining means for determining whether the vehicle speed is equal to or lower than a predetermined vehicle speed, and wherein the vehicle speed is equal to or lower than the predetermined vehicle speed. when the pressure detection value from the pressure sensor, in the predetermined vehicle speed following speed
A lower limit value determining unit that determines whether the pressure sensor is equal to or less than a lower limit value that cannot be indicated, and determines that the pressure sensor is abnormal if the pressure detection value is equal to or less than the lower limit value when the vehicle speed is equal to or less than the predetermined vehicle speed. An abnormality detection device for a pressure sensor of an internal combustion engine, comprising: abnormality determination means.