KR100197142B1 - Misfire detectiing method if internal combustion engine - Google Patents

Abstract

The present invention relates to a misfire detection method of a vehicle engine, and in the explosion of a mixer, the ECU detects misfire due to damage of a crank angle sensor or the like as a signal of the crank angle sensor itself, As the misfire is not easy to detect and requires a separate means, there is a problem that it is difficult to warn the user of the deterioration of the engine due to the deterioration of the ignition ability or to promptly notify the mechanic.

The present invention is illustrated figures the third and the fifth is also the ECU exploded section 26, a fine period and the smile time immediately before the explosion just after the explosion, each of the micro-hour acceleration a _j a _i said to recognize, as in the calculation If the absolute value of the difference (| a _j -a _i |) is smaller than the reference value K set in the ECU, it is determined to be a misfire, and the signal is sent to the engine warning lamp and the self-diagnosis device. Without any additional means, it is possible to detect the engine misfire due to the ignition deterioration even with the existing device alone.

Description

Misfire detection method of vehicle engine

The present invention relates to a misfire detection method of a vehicle engine, and more particularly, in a misfire of an engine caused by a decrease in ignition capability, the misfire may be obtained from a crank angle sensor that is an existing device without a separate means or device for detecting such misfire. A misfire detection method of a vehicle engine that can be detected.

Gasoline engines, commonly referred to as spark ignition engines, are used as spark ignition engines, as opposed to diesel engines, which are compression and ignition engines.The spark plugs used in the combustion chamber are compressed and the pistons are located at the top dead center. The resulting explosion of the mixer is the power source.

Therefore, it is important that the spark plug is discharged at an appropriate position of the piston, and in a vehicle equipped with an electronically controlled fuel injection device, the discharge of the spark plug is controlled by an ECU (Electronic Control Unit) from the crank angle sensor and the advance device. have.

1 is a schematic view showing the principle of the crank angle sensor, Figure 1 (a) is a schematic diagram showing the representation principle of the crank angle by the target wheel, Figure 1 (b) is a configuration diagram of the crank angle sensor. 1C shows a signal input from the crank angle sensor to the ECU.

Permanent magnets are built into the crank angle sensor 10, whereby magnetic force lines are formed. In addition, a crank pulley or a fly wheel is provided with a target wheel 12, and the target wheel 12 is provided with teeth 14 of a gear at regular intervals.

Therefore, when the crankshaft of the engine is rotated, the target wheel 12 is rotated to interrupt the magnetic lines of the crank angle sensor 10, and the waveform of (c) is generated according to the angle θ where each tooth 14 is moved. Will be.

The AC waveform generated at this time, that is, the signal generates twice the cycle signal of the target wheel teeth when the crankshaft rotates once. Therefore, the ECU detects the rotational speed of the engine by dividing the number of signals input for one minute by twice the number of teeth 14 of the target wheel 12.

Therefore, the ECU adjusts the fuel injection amount according to the engine speed, and also, a part of the target wheel 12 has a portion where the teeth of the gear are omitted depending on the appropriate ignition timing, and the occurrence of the waveform is different at this point. This signal causes the spark plug to work.

On the other hand, the maximum explosive force in the engine occurs when the crank angle is about 10 degrees from the top dead center, and the omission point of the teeth described above is determined by the angle.

The point of occurrence of the maximum explosion force is the point of maximum explosion pressure of the mixer, which does not coincide with the point of ignition. That is, considering that the number of revolutions per minute of the target wheel 12 according to the engine speed is high, and the period of the waveform according to the angle θ of the tooth 14 is extremely minute time, the minute time between the ignition time and the maximum explosion pressure generation time There is a gap.

Exemplary drawing FIG. 2 is a schematic diagram illustrating this, and the normal combustion process may be divided into an ignition point 16, a combustion point 18, a maximum explosion pressure point 20, and a combustion end point 22. When the time point 20 is about 10 ° from the top dead center 24, the maximum output power of the engine is generated, and the dotted line shown from the combustion time point 18 represents the change of the diesel misfire.

In addition, since the viewpoints vary according to the engine speed, it is an advance device to adjust the ignition point 16 so that the viewpoint of the maximum explosion pressure 20 is about 10 °, and such an advance device is a crank angle sensor. In conjunction with (10), the ECU controls the ignition point.

Therefore, when an error signal is input to the ECU due to a breakage of the crank angle sensor 10, a failure in assembling the target wheel 12, or a broken tooth, the ECU malfunctions or does not operate the spark plug.

In this case, the ECU sends a signal to the warning lamp of an engine failure located on the instrument panel of the vehicle and sends a signal to the self-diagnosis device, and a maintenance worker may cause a spark plug malfunction or misfire due to damage of the crank angle sensor or the like from the signal of the ECU. You can judge.

Here, the meaning of the misfire is a small meaning of the operation stop of the spark plug, as well as the case that the explosion stroke does not occur due to the deterioration of the ignition ability also belongs to the category of misfire, in this case is not a phenomenon associated with damage to the crank angle sensor, etc. to be.

In more detail, as described above, in general, the spark of the spark ignition engine is caused by electric discharge, and when the spark is blown into the mixer by the electric discharge, a hot gas nucleus called a flame nucleus is formed.

It is the process of spark ignition until the gas nucleus grows and a flame plane capable of self-propagating is established, and when the flame energy is insufficient, the flame nucleus dies and dies.

This phenomenon affects the deterioration of the ignition ability generated, such as discharge type, discharge time, electrode shape, flame interval length, mixing ratio of the mixer, temperature, laminar flow, turbulent flow, and the like. It is irrelevant to damage or the defect of the target wheel 12.

Therefore, the misfire due to the deterioration of the ignition ability does not have a separate detection means directly in the vehicle body, and the measurement of the flame energy is performed by measuring voltage and current using a voltage divider and a current sensor having excellent frequency characteristics and calculating the time integration of the product. A separate detection means is required, such as obtaining or using a calorimetry method.

As described above, the spark plugs cause the ECU to discharge from the crank angle sensor at the optimum piston position to explode the mixer.

However, in the explosion of the mixer, the ECU detects misfire due to damage of the crank angle sensor or the like by means of the signal of the crank angle sensor itself, but misfire due to the lowering of the ignition ability is not easy to detect. Since a means is required, there is a problem that it is difficult to warn the user of the deterioration of the engine due to the deterioration of the ignition ability or to promptly inform the mechanic.

Therefore, the present invention has been devised to solve the above problems and can easily notify a user or a mechanic of a misfire due to a decrease in ignition capability from a signal of a crank angle sensor, which is an existing device, without a separate device. It is an object of the present invention to provide a misfire detection method for a vehicle engine.

The present invention for this purpose is focused on the difference between the angular velocity of the crankshaft per minute before the explosion and the angular velocity of the minute time immediately after the explosion due to the explosion, by comparing the angular velocity change of the minute time that is the period of the teeth of the crank angle sensor, that is, the angular acceleration of the target wheel When the absolute value of the difference of each acceleration is smaller than the reference value K set in the ECU, it is recognized as a misfire, the engine warning lamp is turned on, and the signal is sent to the self-diagnosis device.

Therefore, it is easy to detect misfire due to a decrease in ignition capability from a crank angle sensor, which is an existing apparatus, without any separate detection means such as a voltage divider, a current sensor or a calorimeter method as described above.

1 (a) is a schematic diagram showing the principle of the crank angle representation by the target wheel.

(b) is a schematic diagram which shows crank angle detection by a crank angle sensor.

(c) Schematic diagram showing signals input to the ECU from the crank angle sensor.

2 is a schematic diagram showing changes in the combustion chamber pressure from the ignition point in the micro section.

Figure 3 is a schematic diagram showing the pressure change of the combustion chamber for explaining the detection method according to the present invention.

Figure 4 (a) is a schematic diagram showing the use of the target wheel for the detection method according to the present invention.

(b) is a schematic diagram showing the use of a signal for the detection method according to the invention.

5 is a flowchart of a detection method according to the present invention.

* Explanation of symbols for main parts of the drawings

10 crank angle sensor 12 target wheel

14: tooth 16: ignition timing

18: combustion time 20: maximum explosion pressure

22: end of combustion 24: top dead center

26: explosion section

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

According to the present invention, the ECU has a signal period T _i , T _{i + 1} , T _j which is the signal period of the teeth 14 of the target wheel 12 around the explosion section 26 and the explosion section 26 from the signal of the crank angle sensor. , T _{j + 1} is recognized, and each acceleration a _j of the target wheel 12 in the minute section immediately after the explosion (ΔT _j = T to T _{j + 1} ) and the minute section just before the explosion (ΔT _i = T _i to T _{i + 1} ) calculates each acceleration a _i of the target wheel 12 and turns on the engine warning light when the absolute value (| a _j -a _i |) of the car is smaller than the reference value K previously set and stored in the ECU. It is a misfire detection method of a vehicle engine that sends a control signal informing the engine misfire to the self-diagnosis device.

Exemplary Drawings 3 and 4 are schematic diagrams illustrating the principle of the misfire detection method according to the present invention, and Fig. 5 is a flowchart illustrating the misfire detection method according to the present invention.

In the misfire detection method according to the present invention, the periods T _i , T _{i + 1} of the n target teeth 12 before the explosion 12 and n target teeth 12 immediately after the explosion centering on the explosion section 26. The ECU recognizes the periods T _j and T _{j + 1} of (14), detects the angular velocity and the target wheel angular acceleration from the period, compares the respective accelerations, and detects misfire of the engine.

Accordingly, the ECU sets a reference value K for comparing the difference between the T _i , T _{i + 1} , T _j , T _{j + 1} and the explosion section 26 and the acceleration a _j a _i and the difference between the acceleration a _j a _i . It should be natural.

The explosion section 26 is a section from the combustion time point 18 to the maximum explosion pressure time point 20, as shown in FIG. Check the periods T _i , T _{i + 1} , T _j , and T _{j + 1} , and find the angular velocity corresponding to each period.

Here, the meaning of n means that the period of the waveform generated in one tooth of the target wheel 12 as described above is extremely minute time, it is difficult to compare the angular velocity comparison according to the present invention in one waveform with a reference value k. Since n is an experimentally determined number n, these n numbers have the same value for T _i , T _{i + 1} , T _j , and T _{j + 1} .

The angular velocity is different for each period, which means that when an explosion occurs at the top dead center, the explosive force is transmitted to the piston, and the piston rotates the crankshaft through the connecting rod. T _j and T _{j + 1} are shorter than the periods T _i and T _{i + 1 of the} tooth just before the explosion.

In other words, the teeth 14 of the target wheel 12 are formed at regular intervals as described above, and the angle at which the n teeth set before and after the explosion section 26 are moved is the same, but due to the explosive force, Since T _j, T _{j + 1} cycle and T _j, different from each other, the period of T _{j + 1,} an angular velocity per hour angular displacement of the angular velocity corresponding to the T _i, T _{i + 1} and T _j, T _{j + 1} Will be different.

As a result, the acceleration a _{j which is the} amount of change in angular velocity in the minute section ΔT _j = T _j to T _{j + 1} immediately after the explosion and the angular velocity in the minute section ΔT _i = T _i to T _{i + 1} immediately before the explosion The amount of change a _i is different.

Therefore, the ignition is carried out correctly, the explosion was placed effectively difference absolute value of the acceleration _{(| a j - a i |} ) in the case of misfire ignition is not performed properly, the absolute value of the difference of the acceleration (| a _j - a _i |) Obviously has a different value.

On the other hand, the absolute value (| a _j -a _i |) of the difference of the acceleration that the explosion was properly performed will have a reference value K value considering the structure of the combustion chamber, the engine displacement or fuel, and the surrounding conditions, the K in advance to the ECU It is set to compare the difference of acceleration with the K.

The K does not necessarily mean a standardized value, and since the K may vary according to various situations of the engine being driven, it is also possible to set the minimum value K in the ECU, and table K according to the situation. It is also possible to set.

If the absolute value (| a _j -a _i |) of the difference in acceleration is smaller than K, this means that the piston is not subjected to the force due to the explosion of the mixer, so that the dotted line after the combustion point 18 in FIG. ECU determines this to be a misfire.

In this case, the ECU turns on the engine warning lamp described above, and sends out the control signal of the misfire to the self-diagnosis apparatus.

Therefore, in the case of misfire due to the lowering of the ignition capability, the present invention can detect the signal from the crank angle sensor, which is an existing device, and the operation process of the ECU without the above-described means.

As described above, according to the present invention, the ECU recognizes the micro-period immediately after the explosion and the micro-time immediately before the explosion in the explosion section 26, and calculates the accelerations a _j a _i for each micro-hour and calculates the absolute value of the difference (| a _{If j} -a _i |) is smaller than the reference value K set in the ECU, it is determined to be a misfire, and the signal is sent to the engine warning lamp and the self-diagnosis device, so that the existing device alone without any voltage divider, current sensor or calorimeter method. The engine misfire due to the deterioration of the ignition ability can be detected.

Claims (1)

The ECU the signal cycle of the tooth profile 14 of the target around the blast zone (26) and the blast zone 26 from the signal of the crank angle sensor wheel _{(12) T i, T i} + 1, T j, T j Recognizing ₊₁ , each acceleration a _j of the target wheel 12 in the microsection immediately after the explosion (ΔT _j = T _j to T _{j + 1} ) and the microsection immediately before the explosion (ΔT _i = T _i to T _i Calculate the angular acceleration a _i of the target wheel 12 at ₊₁ ) and if the absolute value (| a _j -a _i |) of the car is smaller than the reference value K previously set and stored in the ECU, the engine warning lamp is turned on and the magnetic A misfire detection method for a vehicle engine that transmits a control signal for notifying engine misfire to a diagnostic device.