JPH0734946A - Fuel system abnormality diagnostic device for internal combustion engine - Google Patents

Abstract

PURPOSE:To judge abnormality in a total fuel system or in a fuel system of each cylinder regardless of a control system of an internal combustion engine in a multi-cylinder internal combustion engine provided with a learning control device for each cylinder by using each correction value set for each cylinder by a learning means of each cylinder. CONSTITUTION:In a multi-cylinder internal combustion engine 1, the quantity of intake air is adjusted by a throttle valve 3, and is detected by an air flowmeter 4. The engine speed is detected by a crank angle sensor 5. Further, an O2 sensor 9 for detecting the concentration of oxygen in exhaust gas, namely the air-fuel ratio, is installed on an exhaust pipe collective part of each cylinder. A control unit 6 controls the fuel injection quantity of a fuel injection valve 7 based on respective detection signals, and corrects dispersion of the air fuel ratio in each cylinder. In this case, the control unit 6 judges abnormality in the engine fuel system, according to each correction value set for each cylinder. That is, an average value of the respective correction values is determined, and when the average value deviates from a specified range, abnormality is judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION In a multi-cylinder internal combustion engine provided with at least a cylinder-by-cylinder learning control device, based on a correction value set for each cylinder by a cylinder-by-cylinder learning means, a fuel system for the internal combustion engine and a fuel system for each cylinder are provided. The present invention relates to an internal combustion engine fuel system diagnostic device for determining abnormality or failure of the internal combustion engine.

[0002]

2. Description of the Related Art In order to detect an abnormality of a fuel system of an internal combustion engine, an air-fuel ratio correction value or a learning value of an air-fuel ratio which is set based on an output signal of an exhaust gas concentration detector for detecting the exhaust gas concentration of the internal combustion engine is used. Used. It is known that an abnormality of the fuel system is determined by comparing the air-fuel ratio correction value or the learned value with a predetermined range (for example, Japanese Patent Laid-Open No. 3-249348).

Another conventional technique is a cylinder-by-cylinder diagnostic device in a fuel supply control device for an internal combustion engine (for example, Japanese Laid-Open Patent Publication No. 2-301644).

[0004]

However, in the prior art for diagnosing the fuel system abnormality of the internal combustion engine as described above,
Only the abnormality of the entire fuel system of the internal combustion engine can be diagnosed.
Also in the cylinder-by-cylinder diagnosis device, the abnormality diagnosis method depends on the control method of the internal combustion engine. In the present invention, by using the correction value set for each cylinder of the internal combustion engine including at least the cylinder-by-cylinder learning control device, the entire fuel system of the internal combustion engine and the fuel system of each cylinder are irrespective of the control system of the internal combustion engine. The problem is to be able to diagnose abnormalities.

[0005]

[Means for Solving the Problems] Comparing the absolute value of the average value of learning values (correction values) set in each cylinder of an internal combustion engine equipped with at least a cylinder-by-cylinder learning control device with a predetermined upper and lower limit value. This is accomplished by using both an average value and a cylinder-by-cylinder correction value comparison.

[0006]

By the above means, a simple diagnosis system can be provided, and it can be applied to any system equipped with a cylinder-by-cylinder learning control device to provide a versatile fuel system abnormality diagnosis system.

[0007]

FIG. 1 is an explanatory diagram of an internal combustion engine to which the present invention is applied. The intake air amount Qa of the internal combustion engine (1) is controlled by the throttle valve (3) and simultaneously measured by the air flow meter (4), and a signal of Qa is input to the control unit (6). On the other hand, the rotation speed of the internal combustion engine is detected by the crank angle sensor (5), and a signal as N is input to the control unit. The control unit calculates the pulse width Ti for driving the supply injection valve (7) with the fuel amount corresponding to these Qa and N. One injection valve is attached to each intake pipe (2) cylinder of the internal combustion engine (for example, four cylinders are attached to four). The fuel is pressurized by the fuel pump and guided to the injection valve. Oxygen concentration in the exhaust gas, that is, A / F
An O2 sensor (9) for detecting (air-fuel ratio) is attached and inputs an A / F signal to the control unit. Although not shown here, this internal combustion engine is provided with feedback control means, cylinder-specific learning means, and the like.

FIG. 2 shows a system block diagram of the present invention, in which the learning correction value set by the cylinder-based learning correction value setting means is based on the correction value set by the feedback correction value setting means in the internal combustion engine. Used for cylinder-by-cylinder learning control means. The average value of the cylinder-by-cylinder correction values is obtained by the correction value averaging processing means, and based on the average value, the fuel system abnormality determining means determines the abnormality or failure of the fuel system. Further, the deviation between the average value and the correction value for each cylinder is calculated by the correction value deviation processing means for each cylinder, and the abnormality or failure of the fuel system of each cylinder is detected by the fuel system abnormality determining means.

FIG. 3 shows a case in which the above-mentioned correction value averaging means obtains an average value of each cylinder and compares it with an allowable range for determining an abnormality to determine an abnormality. The upper limit value and the lower limit value here are set by an allowable value that the correction value of the entire cylinder can take or an allowable value that does not exceed the exhaust standard. When the entire cylinder exceeds this allowable range, it is determined that an abnormality has occurred in the fuel system of the internal combustion engine. here,
It can be inferred that there is an abnormality due to a failure of the intake air flow meter or an abnormal change in fuel pressure.

FIG. 4A shows a case in which an abnormality in the fuel system of the internal combustion engine is determined. Represents the magnitude of the correction value for each cylinder. As shown in the figure, the average value of each cylinder is obtained by the above correction value averaging processing means, the upper limit value and the lower limit value are provided by this average value, and each cylinder is corrected by the above correction value deviation processing means for each cylinder. Cylinder difference of the correction value set to
That is, the deviation values with respect to the average value are obtained, and it is judged whether or not these deviation values exceed the upper limit value or the lower limit value. If the correction value of a specific cylinder exceeds (see FIG.
(B)) It is determined that an abnormality has occurred in the fuel system of the cylinder. The upper limit value or the lower limit value described above is set according to the allowable value of the fuel supply characteristic variation of the fuel system that does not adversely affect the drivability of the internal combustion engine. For example, it is set to ± 5% of the average value of the correction values. With this abnormality determining means, it is possible to infer a failure due to deterioration or clogging of the fuel injection valve for each cylinder.

Further, as shown in FIG. 5, in the abnormality diagnosis based on the changing speed of the correction value set in each cylinder, the amount of change in the correction value set in each cylinder at a predetermined time is within a predetermined allowable value. When it exceeds, it is determined that an abnormality has occurred in the fuel system for each cylinder.

FIG. 6 shows a flow chart for detecting an abnormality in the fuel system of the present invention.

In step 1 (S1), it is judged whether or not the diagnostic condition is satisfied.

In step 2 (S2), the average value Kave of the correction values for each cylinder is calculated.

In step 3 (S3), it is judged whether or not the average value obtained in S2 exceeds the upper limit value / lower limit value, and if it exceeds, S4 is executed and an abnormality occurs in the fuel system of the internal combustion engine. Determine that If the upper and lower limits are not exceeded, the process proceeds to step 5 (S5) to calculate the deviation value Kdn of the correction value for each cylinder from the average value. In step 6 (S6), it is determined whether the deviation value for each cylinder calculated in S5 exceeds a predetermined value. If it exceeds, it is determined that an abnormality has occurred in the fuel system of the cylinder (S7). .

In step 8 (S8), the learning control of the cylinder determined to be abnormal in S7 is stopped, and the learning value is set based on the previous correction value that did not exceed the predetermined value.

Although not shown, by using a counter or a flag, when the abnormality is detected more than a certain number of times, the abnormality code is stored and the abnormality is notified to the driver.

Further, as another abnormality determining means, the pattern recognizing means recognizes the correction value for each cylinder and determines the abnormality by the pattern of the correction value for each cylinder.

[0019]

According to the present invention, in the internal combustion engine having at least the learning control device for each cylinder, the correction value set for each cylinder is used to cause abnormality or failure of the fuel system of the internal combustion engine and the fuel system of each cylinder. The effect of being able to determine

[Brief description of drawings]

FIG. 1 is a diagram showing a main configuration of the present invention.

FIG. 2 is a block diagram of the present invention.

FIG. 3 is a diagram showing an example of abnormality diagnosis.

FIG. 4 is a diagram showing an example of abnormality diagnosis.

FIG. 5 is a diagram showing an example of abnormality diagnosis.

FIG. 6 is a flowchart of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Intake pipe, 3 ... Throttle valve, 4 ... Intake air flow meter (air flow meter), 5 ... Crank angle sensor, 6 ... Control unit, 7 ... Fuel injection valve, 8
… Exhaust pipe, 9… O ₂ sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Ishii 2520 Takaba, Katsuta City, Ibaraki Prefecture Hitachi Ltd. Automotive Equipment Division

Claims (10)

[Claims] 1. A sensor group for detecting an operating state of a multi-cylinder internal combustion engine, an arithmetic processing unit for calculating at least the amount of fuel supplied to the internal combustion engine based on information from each sensor group, and an air-fuel ratio of each cylinder of the internal combustion engine. In a multi-cylinder internal combustion engine provided with a control device for an internal combustion engine having cylinder-by-cylinder learning means for correcting variations, it is possible to determine an abnormality of a fuel system of the internal combustion engine based on a correction value set for each cylinder. Characteristic,
Fuel system abnormality diagnosis device for internal combustion engine. 2. The fuel system according to claim 1, wherein an average value of the correction values set for each cylinder is obtained, and when the average value is out of a predetermined predetermined region, an abnormality has occurred in the fuel system. A fuel system abnormality diagnostic device for an internal combustion engine, characterized by: 3. The method according to claim 1, wherein when the difference between the cylinders in the correction value set for each cylinder exceeds a predetermined value, it is determined that an abnormality has occurred in the fuel system of the cylinder. A fuel system abnormality diagnostic device for an internal combustion engine. 4. The fuel system of the internal combustion engine according to claim 1, wherein when the average value of the correction values set for each cylinder and the inter-cylinder difference each exceed a predetermined value, an abnormality occurs in the fuel system of the internal combustion engine. A fuel system abnormality diagnostic device for an internal combustion engine, which is characterized in that it is determined that there is an abnormality. 5. The method according to claim 1, wherein when the rate of change of the correction value set for each cylinder exceeds a predetermined value, it is determined that an abnormality has occurred in the fuel system of the cylinder. Abnormality diagnosis system for internal combustion engine. 6. A fuel system abnormality of an internal combustion engine according to claim 1, 2, 3, 4 or 5, characterized in that when abnormality of the fuel system is determined, learning of a cylinder determined to be abnormal is stopped. Diagnostic device. 7. When the abnormality of the fuel system is judged in claim 1, 2, 3, 4, 5 or 6, it is possible to correct the amount of fuel supplied to cylinders other than the cylinder judged to be abnormal. A fuel system abnormality diagnostic device for an internal combustion engine, which is characterized. 8. The method according to claim 1, 2, 3, 4, 5, 6 or 7, wherein when the abnormality of the fuel system is judged at least twice or more, it is judged that the fuel system of the internal combustion engine is out of order. A fuel system abnormality diagnosis device for an internal combustion engine. 9. Claims 1, 2, 3, 4, 5, 6, 7 or 8
In the above, the fuel system abnormality diagnosis device for an internal combustion engine, which stores a failure code when it is determined that the fuel system is out of order. 10. Claims 1, 2, 3, 4, 5, 6, 7, 8
Alternatively, the fuel system abnormality diagnosis device for an internal combustion engine, characterized in that when the fuel system is determined to be faulty, the driver is notified of the fault.