KR950013547B1 - Misfiring abolding method for an internal combustion engine - Google Patents

Abstract

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Description

Misfire control device and misfire control method of internal combustion engine

1 is a flowchart showing one embodiment of this invention.

2 is a flowchart showing an example of the myth determination information calculation routine of FIG.

3 is a configuration diagram showing a general internal combustion engine misfire determination device.

* Explanation of symbols for main parts of the drawings

10: ECU 20: ion current detector

21: diode 22: load resistor

23: DC power supply 24, 25: voltage divider (voltage generating means)

26 condenser 27 comparator

28, 29: voltage divider (threshold generating means)

V: Ion Ammeter

Q: Misfire rate (misfire determination information) α ₁ : 1st reference value

α ₂ : second reference value S 30: step of calculating misfire determination information

S31: comparing the misfire determination information with the first reference value

S32: comparing the misfire determination information with the second reference value

S33: step prohibiting the supply of fuel

S36, S27: Steps for performing the control titration process, and the same or corresponding parts are indicated by the same reference numerals in the drawings.

The present invention relates to a method of controlling the misfire state of an internal combustion engine on the basis of misfire information of a cylinder after an ignition stroke, and in particular, a misfire control apparatus and a misfire control method of an internal combustion engine which improves misfire controllability by judging the misfire state step by step. It is about.

In general, an internal combustion engine used for automobile gasoline engines or the like is driven by four cycles of intake, compression, explosion, and exhaust by a plurality of cylinders (for example, four cylinders).

In such an internal combustion engine, calculation is performed electronically by a microcomputer in order to optimally control the ignition timing, fuel injection sequence, and the like for each cylinder.

For this reason, the microcomputer inputs the reference position signal for each cylinder synchronized with the rotation of the internal combustion engine and the cylinder identification signal corresponding to the specific cylinder in addition to the various operating conditions, thereby identifying the operating position for each cylinder and controlling it at the optimum timing. .

As a means for generating the reference position signal and the cylinder identification signal, a rotation signal generator for detecting the rotation of the cam shaft or the crank shaft of the internal combustion engine and generating a synchronization signal is used.

For example, in the ignition control of each cylinder, the mixer compressed by the piston needs to be burned by the spark of the spark plug, but depending on the state of the fuel or the spark plug, the ignition controlled cylinder may not be burned.

If such a condition occurs, abnormal load is applied to other cylinders, which may cause damage to the engine and cause various obstacles due to leakage of unburned gas.

Therefore, in order to ensure the safety of the engine, it is necessary to detect whether the combustion is sure for each cylinder every ignition stroke cycle.

For this reason, the apparatus which detects the ion current which generate | occur | produces between the gaps of a spark plug as a misfire information, and discriminates combustion or a misfire state is proposed conventionally.

3 is a block diagram showing a general internal combustion engine misfire determination apparatus using ion current as misfire information.

In the figure, 1 is a crankshaft serving as a drive shaft of the internal combustion engine, and is connected to a piston of a plurality of cylinders (not shown) so as to be driven in rotation.

2 is a cam shaft which rotates in synchronism with the crank shaft 1, and 3 is a timing belt which connects the crank shaft 1 and the cam shaft 2 to each other.

In the case of a general four-cycle engine, suction, compression, explosion, and exhaust are performed for two revolutions of the crankshaft 1, and the camshaft 2 rotates once for two revolutions of the crankshaft 1, and the camshaft (2) One rotation is made in synchronization with one cycle of the four-cycle operation of each cylinder.

Therefore, in the case of the four-cylinder engine, there is a phase difference in the rotational position of each cylinder by 1/2 cycle (180 °) of one revolution with respect to the crankshaft 1, and a phase difference by 1/4 cycle with respect to the camshaft.

4 is a rotating shaft of the rotation signal generator connected to the cam shaft 2, 5 is a rotating disc for detecting the reference position provided at one end of the rotating shaft (4).

6 is a slit-shaped window formed in the rotating disk 5, and is provided so as to correspond to the reference position (predetermined rotation angle) for each cylinder.

The rotating disc 5 is provided with a window (not shown) for cylinder identification corresponding to the specific cylinder, as necessary.

8 is a stationary plate which is disposed to face a part of the rotating disc 5.

The fixed plate 8 is provided with a photocoupler sensor (not shown) facing the window 6, and generates a reference position signal L for each cylinder.

Here, one end of the front side in the rotational direction of the window 6 corresponds to the first reference position of each cylinder, one end of the rear side of the window 6 corresponds to the second reference position of each cylinder, and the reference position signal L is the first. The pulse waveform rises from the reference position and falls from the second reference position.

Numeral 10 denotes a microcomputer constituting an electronic control device (hereinafter, abbreviated as ECU), and performs fuel control and ignition control of each cylinder based on the reference position signal L and operation status signals from various sensors not shown. .

The ECU 10 is provided with distribution means for ignition control of each cylinder in accordance with the determined cylinder sequence.

11 is a power transistor of the emitter ground driven by the ignition signal D from the ECU 10, 12 is an ignition coil whose primary coil side is connected to the power transistor 11, and 13 is a secondary of the ignition coil 12. Spark plugs 14, which are focused on the coil side, are reverse flow prevention diodes inserted between the ignition coil 12 and the spark plug 13.

In addition, although the ignition part for one cylinder is represented here typically, such an ignition part is installed in each cylinder.

20 is a reverse flow prevention diode 21 connected to one end of the spark plug 13 as an ion flow detector between one end of the spark plug 13 and the ECU 10, and a load resistor connected to the cathode of the diode 21. Positive voltage DC power supply 23 connected in series to 22 and load resistor 22, and voltage divider resistors 24 and 25 connected in parallel to a series circuit consisting of cupping resistor 22 and DC power supply 23. ), The capacitor 26 inserted into the connection point of the load resistor 22 and the voltage divider 24, and the connection point of the voltage divider 24 and 25 are connected to the comparison input terminal (-) of the comparator, Voltage divider 28 and 29 for connecting the comparator 27 connected to the self-contained ECU 10 and the threshold TH from the intermediate connection point to the reference input terminal (+) of the comparator 27 connected in series. Equipped with.

The voltage divider resistors 24 and 25 constitute a voltage generating means for generating a voltage (ion current value) V corresponding to the ion current I, and the voltage divider resistors 28 and 29 generate threshold values TH, which are the combustion determination criteria. The threshold generation means is configured.

The ion current value V is input to the comparator 27 as misfire information. The ion current detector 20 having the above-described configuration is provided only to the spark plug 13 of a specific cylinder or to the spark plug 13 for each cylinder as necessary.

The following describes the conventional internal combustion engine misfire determination method and the misfire avoidance method using the internal combustion engine misfire determination device of FIG.

When the rotating disc 5 rotates like the cam shaft 2 which cooperates with the crankshaft 1, the reference position signal L corresponding to the window 6 is output from the photocoupler sensor on the fixed plate 8.

The reference position signal L becomes, for example, a waveform rising from the first reference position B75 ° of each cylinder and falling from the second reference position B5 °.

The first reference position B75 ° is the position of the crank just before 75 ° from the TDC (top dead center), and corresponds to the control reference and initial conduction angle.

The second reference position B5 ° is the crank angle position just before 5 ° from the TDC, and corresponds to the initial ignition position at the time of cranking.

Another cylinder identification signal (which can be included in the reference position L) is output when the reference position signal L corresponding to the specific cylinder (for example, one cylinder) is generated.

The reference position signal L thus obtained is input to the ECU 10 together with the operation state signal.

As the operation state signal, for example, the engine (crank) rotation speed and the load state (accelerator opening) are input.

The ECU 10 distributes the ignition signal D for each cylinder identified by the reference position signal L, and turns on the power transistor 11 in the order of # 1 cylinder, # 3 cylinder, # 4 cylinder and # 2 cylinder. "I will.

Then, after energizing the primary coil current of the ignition coil 12 only for the required time, the power transistor 11 is cut off and the secondary coil side of the ignition coil 12 is driven to generate sparks in the ignition plug 13. At this time, the power supply voltage applied to the ignition coil 12 is cut off after being discharged from the negative high voltage or the ignition plug 13.

When an explosion (combustion) occurs in the vicinity of the spark plug 13 by this discharge, a large amount of cations are generated immediately between the gaps of the spark plug 13.

This cation becomes the ion current I and flows through the diode 21 and the load resistor 22 by being attracted to the negative voltage of the current power source 23 between the gaps of the spark plug 13.

The ion current I is converted into a voltage between both ends of the load resistor 22, and then a DC component is removed by the capacitor 26, and is converted into an ion current value V by the voltage dividers 24 and 25, so that the comparator 27 Is input to the comparison input terminal (-).

The ion current value V is usually high when an explosion occurs and becomes low when an explosion does not occur.

On the other hand, the threshold value TH appropriately set in advance by the voltage divider 28 and 29 is input to the reference input terminal + of the comparator 27.

Therefore, the comparator 27 sets the output signal to " off " when the ion current value V is smaller than the threshold TH, and turns the output signal to " on " above the threshold TH. The current detection value C is input to the ECU 10.

The ECU 10 confirms that the combustion is normally performed in the ignition controlled cylinder based on the cylinder identified in each reference position signal and the ion current detection value C.

If the ignition-controlled cylinder is normal, an explosion occurs due to the discharge of the ignition plug 13, and a lot of cations are generated between the ignition plugs 13, but if there is any problem, the cations are hardly generated.

Accordingly, the misfire state of the cylinder can be determined.

When the misfire state is determined, the supply of fuel to the cylinder is prohibited and the outflow of unburned gas due to misfire is avoided.

However, in many ignition administrations, accidents may occur accidentally even without any abnormality, and it is not practical to judge misfires by detecting only one misfire.

In a light misfire state, misfires may be avoided by a control-optimization process such as an increase in ignition energy, and the fact that fuel supply prohibition is always performed at the time of misfire determination is not an efficient misfire control process.

In the conventional internal combustion engine misfire control method, the misfire state is determined only when the ion current value (firewall information) V is lower than the threshold TH as described above. Therefore, even in the case of accidental misfire, misfire determination is not possible and reliable misfire detection cannot be performed. there was.

In addition, when the misfire state is determined, the fuel supply prohibition process is performed irrespective of the degree of misfire, there is a problem that the misfire avoidance control is not efficient.

The present invention has been devised to solve the above problems, and a reliable misfire determination using the misfire determination information by statistical processing and the misfire determination information are processed step by step to improve the misfire avoidance control. The purpose is to obtain a control method.

The internal combustion engine misfire control method according to the present invention comprises the steps of calculating the misfire determination information by statistically processing the misfire information of the cylinder after the ignition stroke, comparing the misfire determination information with the first reference value, and the misfire determination information with the first reference value. In this case, the step of comparing the misfire determination information with the second reference value larger than the first reference value, the step of prohibiting supply of fuel to the cylinder when the misfire determination information is equal to or greater than the second reference value, and the misfire determination information are the first reference value. And a step of performing a control-optimization process on the cylinder when it is between the second reference value and the second reference value.

In the present invention, when the misfire state based on the statistically corrected misfire determination information is at a high level, misfire control by fuel supply prohibition is performed, and when it is light, misfire control by control adequacy processing is performed.

Hereinafter, one embodiment of this invention will be described with reference to the drawings.

1 is a flowchart showing one embodiment of the present invention, and FIG. 2 is a flowchart showing an example of the misfire determination information calculation routine in FIG.

As the apparatus to which the present invention is applied, for example, as shown in FIG. 3, 10 is a microcomputer constituting an electronic control apparatus (hereinafter, abbreviated as ECU). Operation from a reference position signal L and various sensors not shown. Fuel control and ignition control for each cylinder are performed based on the status signal, and the ECU 10 is provided with distribution means for ignition control of each cylinder in accordance with the determined cylinder sequence.

20 is a reverse current prevention diode 21 connected to one end of the spark plug 13 as an ion current detector between one end of the spark plug 13 and the ECU 10, and a load resistor connected to the cathode of the diode 21. (22), a positive voltage grounded DC power supply 23 connected in series to the load resistor 22, and a voltage divider resistor 24 connected in parallel to a series circuit of the load resistor 22 and the DC power supply 23; 25, the capacitor 26 inserted into the connection point of the load resistor 22 and the voltage divider 24, and the connection point of the voltage divider 24 and 25 are connected to the comparison input electron (-) of the comparator 27. And a voltage divider 28 in which the output terminal is connected in series with the comparator 27 connected to the ECU 10, and the threshold TH is input from the intermediate connection point to the reference input terminal (+) of the comparator 27 from the intermediate connection point. And (29).

The voltage divider resistors 24 and 25 constitute voltage generation means for generating a voltage (ion current value) V corresponding to the ion current I, and the voltage divider resistors 28 and 29 set the threshold value TH, which is a combustion determination criterion. The threshold value generating means is generated.

The ion current value V is input to the comparator 27 as misfire information. Here, the ECU 10 only needs to include misfire determination means for statistical processing and misfire control means for controlling misfire based on the misfire determination information.

The function of the threshold generating means and the comparator may be included in the ECU 10, and if necessary, the ion current value may be converted by AD conversion after peak hold or integration, or the threshold TH may be corrected in accordance with the operating state.

Thus, the peak hold or integrated misfire information can be used to prevent false detection even when noise pulses overlap the misfire information.

In this case, the ECU 10 includes an AD converter for converting misfire information corresponding to the level of the ion current value V into a digital signal, a threshold calculator for calculating a threshold TH based on the reference position signal L and an operation state signal, and the AD conversion. And a comparison section for outputting the misfire detection signal by comparing the misfire information with the threshold TH.

As the misfire information, not only the ion current I in the cylinder after lactation but also the pressure in the cylinder may be used.

In this case, misfire is detected when the pressure in the cylinder after the ignition stroke is lower than the reference value.

The reference value is a combustion determination reference value, which is set in advance by the threshold value setting means. In other words, it is a reference value determined according to rotation speed, load, fuel injection amount, water temperature and intake temperature, and the first reference value and second reference value based on fuel injection amount are searched by searching the threshold map (MAP) according to the rotation speed and load of the internal combustion engine. It is set to a value satisfying the relationship of.

In addition, the reference value is corrected according to the rotational speed, load, fuel injection amount, water temperature and intake temperature.

Here, a case where the ion current value V is the misfire information as described above will be described.

First, the ion current value (misfire information) V is statistically processed to calculate the misfire rate (misfire determination information) Q (step S30).

Next, the misfire rate Q is compared with the 1st reference value (alpha) ₁ (step S31), and when it is 1st reference value (alpha) ₁ or more, it compares again with the 2nd reference value (alpha) ₂ larger than 1st reference value (alpha) ₁ (step S32).

If the misfire rate Q is equal to or higher than the second reference value α _2, it is regarded as a high-level misfire state, and the fuel supply to the cylinder is prohibited (step S33).

The misfire rate Q that is the first reference value α at least _one addition, and is less than a second reference value that is just between the first reference value α ₁ and the second reference value α ₂ is set to control optimization flag for that cylinder (step S34) After confirming that the control titration flag is set (step S35), the misfire control is performed by the control titration process (steps S36 and S37), and then the process is returned. In this case, at least one of the ignition energy increasing process (step S36) and the optimization of the air-fuel ratio A / F (step S37) are performed as the control titration process.

In general, the proper air-fuel ratio varies depending on the driving conditions, but is about 14.7 by weight.

In step 36, the voltage applied to the spark plug is increased or a continuous ignition process is performed. In step S37, the air-fuel ratio is set to an optimum value.

This avoids light misfire and achieves normal combustion.

On the other hand, when it is determined in step S31 that the misfire rate Q is smaller than the first reference value α ₁ , it is not an abnormal misfire, but a misfire within the allowable range. Proceed to S35.

When it is determined in step S35 that the control optimization flag is not set, the process returns to that state.

When it is determined in step S31 that the misfire rate Q is smaller than the first reference value, the misfire determination flag (not shown) for the cylinder is reset, and in step S32, the misfire rate Q is the second reference value α _2. In the case of the above determination, a misfire determination flag may be set.

When the misfire determination flag is set in this way, for example, information or indicators indicating abnormal misfire can be driven.

Next, an example of the misfire determination information calculation routine in step S30 will be described with reference to FIG. First, the ignition counter CNT1 for counting the ignition count, the misfire counter CNT for counting the misfire detection count, the misfire determination flag, and the counting start flag XFC are reset.

In addition, N1 of a predetermined number of times for determining the calculation timing of the misfire rate Q is set in advance. The ECU 10 discharges the spark plug 13 at a predetermined timing based on the reference position signal L corresponding to the crank angle of each cylinder.

At this time, the ion current I generated between the gaps of the ignition plug 13 is converted to the ion current value V by the ion current detector 20, and then peak hold or integrated, for example.

The ECU 10 converts the peak hold or integrated ion current value at a predetermined timing based on the reference position signal L and inputs it as misfire information (step S31).

Next, the ignition counter CNT1 is incremented (step S11), and the misfire information is compared with the threshold TH, and if the misfire information V is less than or equal to the threshold TH, it is determined whether the counting start flag XFC displays the counting start (XFC = 1). (Step S12).

If the count starts (XFC = 1), the misfire counter CNT is incremented (step S3), and the misfire detection count is counted.

If the counting start flag (XFC = 0) is set, the counting start flag is set to 1, and the increments of the counters CNT1 and CNT are started with the values of the ignition counter CNT1 and the misfire counter CNT as 1 (step S13).

Then, it is determined whether the ignition counter CNT1 reaches the predetermined number of times N1 (step S14).

On the other hand, if it is determined in step S2 that the misfire information V is larger than the threshold TH, the process proceeds directly to step S14.

In step S14, when it is determined that the ignition counter CNT1 has not reached the predetermined number of times N1, the process immediately returns to step S1, and when the ignition counter CNT1 reaches the predetermined number of times N1, it is determined whether the counting start flag XFC is set (step S15). ).

If the counting start flag XFC is set, the thread counter CNT and the predetermined rotation speed N1 are used.

Q = CNT / N1

The misfire rate Q is calculated from (step S16), and the counting start flag XFC and the misfire counter CNT are reset (step S17) to return.

On the other hand, when it is determined in step S15 that the counting start flag XFC is not set, the ignition counter CNT1 is reset (step S7) and then returned.

Accordingly, the ratio of the ignition detection rotation speed CNT in the predetermined ignition frequency N1, that is, the misfire rate Q, is calculated as the misfire determination information.

In this case, since the count start flag XFC is set at the time of the first misfire detection, the count of each counter CNT1 is started (step S13). Therefore, when no misfire occurs, the misfire rate Q is unnecessarily calculated. There is no work.

Since counters CNT1 and CNT are incremented at the time of misfire, the safety axis is calculated so that the misfire rate Q is increased.

Here, the predetermined number of times for misfire determination and the first reference value α ₁ and the second reference value α ₂ are set to predetermined values, but may be corrected according to the operating state.

It is preferable that the threshold TH used in the misfire detection step S2 is corrected in misfire information or an operation state.

This is because, for example, when the number of revolutions or the load of the internal combustion engine is large, the level of the misfire information increases, so it is necessary to set a high threshold TH.

In general, the operation state signal D includes the rotation speed, load, water temperature, intake temperature, and fuel injection amount of the internal combustion engine, and the threshold calculation unit in the ECU 10 searches for a threshold map based on, for example, the rotation speed and the load, and then fuels the fuel. The threshold TH may be corrected based on the injection amount or the like.

In this case, when the fuel injection amount is large, the level of the misfire information V increases, so that the threshold TH is corrected to increase.

The threshold TH may be calculated on the basis of the operating state and misunderstanding without using the threshold selling lights.

In this case, for example, based on true information

TH = VJ

The threshold TH can be calculated from.

J is the correction factor according to the operating state.

Leveling one threshold TH

TH _n = K ₁ TH _n-1 + K ₂ V _n + K

The threshold TH _n can be found at.

TH _n-1 is the previous threshold, V _n is the actual misfire information, and K is the correction term according to the operating condition.

In addition, K ₁ and K ₂ are the averaging coefficients,

1〉 K ₁ 〉 K ₂ 〉 0

Is the range of.

In the above embodiment, the misfire determination information obtained by performing statistical processing on the misfire information V is used as the misfire rate Q. However, the number of persistent misfire detections may be used as the misfire determination information.

In this case, the misfire counter CNT is used to count the number of consecutive misfire detections, and an abnormal misfire is determined when the number of consecutive misfire detections reaches a reference value (predetermined number of times). In other words,

N ₁ <N ₂

When the first reference value N ₁ and the second reference value N ₂ are satisfied and the number of continuous misfire detections reaches the second reference value N ₂ , fuel supply is prohibited, and the first reference value N ₁ and the second reference value N are satisfied. _The control titration process is performed when it is between _two .

The reference values α ₁ and α ₂ for determining the misfire state may be corrected in response to the operating state of the internal combustion engine, that is, the number of revolutions, the load, the fuel injection amount, the water temperature, and the intake air temperature, thereby enabling a more reliable misfire determination. .

For example, when the accelerator pedal is released during high-speed driving, the amount of fuel injection is suppressed and the system becomes a continuous misfire state. However, when the reference values α ₁ and α ₂ are largely explained by driving state signals from various sensors indicating the accelerator opening degree, abnormal misfire There is no misdetection of the state.

In addition, although the case where the ion current is used as the misfire information has been described, it is needless to say that other misfire information, for example, a cylinder internal pressure or the like, has the same effect.

As described above, according to the present invention, a step of statistically processing the misfire information of the cylinder after the ignition stroke to calculate the misfire determination information, a step of comparing the misfire determination information with the first reference value, and the misfire determination information more than the first reference value Comparing the misfire determination information with the second reference value larger than the first reference value, the step of prohibiting the supply of fuel to the cylinder when the misfire determination information is equal to or greater than the second reference value, and the misfire determination information between the first reference value and the second reference value. If there is a control, it is provided with a step for performing a control-optimization process for the cylinder. If the misfire state based on the misfire determination information is at a high level, the misfire control by prohibiting fuel supply is performed; Therefore, it is possible to improve the misfire controllability by processing the misfire determination information step by step while making reliable misfire determination. It is effective to obtain a combustion engine misfire determination method.

Claims (2)

Misfire rate calculation means (S1 to S17) for calculating the misfire detection count within a predetermined ignition number as the misfire rate based on the misfire information of the cylinder after the ignition stroke, and corresponding to the misfire state of the misfire rate and hardness A first comparison means S31 for comparing with a first reference value, and a second comparison value for comparing with the second reference value corresponding to the misfire rate and the moderate misfire state when the misfire rate is equal to or greater than the first reference value. Fuel supply prohibiting means (S33) for prohibiting fuel supply to the cylinder when the comparison means (S32) and the misfire rate are equal to or greater than the second criterion; and the misfire rate is equal to or greater than the first reference value. 2. A misfire control apparatus for an internal combustion engine, characterized by comprising control-optimization processing means (S36 or S37) for performing control-optimization processing on the cylinder when less than 2 reference values. A step (S1 to S17) of calculating the misfire detection count within a predetermined ignition number as the misfire rate based on the misfire information of the cylinder after the ignition stroke, and the first criterion corresponding to the misfire state of the misfire rate and hardness Comparing with the step (S31), when the misfire rate is equal to or greater than the first reference value, the step (S32) and the misfire rate for comparing the misfire rate with a second reference value corresponding to a moderate misfire state Step S33 of prohibiting fuel supply to the cylinder when the second reference value is equal to or greater than the second reference value, and when the misfire rate is equal to or greater than the first reference value and smaller than the second reference value, the control titration process is performed on the cylinder. The misfire control method of an internal combustion engine, characterized by having a step (S36 or S37).