JP2008069692A - Internal combustion engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an internal combustion engine control device preventing its misfire detection performance from being reduced because of manufacturing dispersion, etc., of a crank cycle measuring rotor for detecting misfire especially in an odd number cylinder engine. <P>SOLUTION: The device comprises a crank angle detection means 101 for generating a crank angle signal SGT, a cycle measuring means 103 for obtaining combustion stroke cycles TCcyc(i) and intake stroke cycles TIcyc(i) suitable for the respective cylinders based on the crank angle signal, and a misfire detection means 108 for detecting misfire from a cycle change based on a ratio of each stroke cycle. The cycle measuring means 103 measures each stroke time by using the same position of the crank angle signal SGT. The misfire detection means 108 detects the misfire without being affected by arrangement dispersion of crank angle signal plate teeth with high precision. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control device provided with a misfire detection means, and more particularly to an internal combustion engine control device with improved detection performance when detecting misfire using rotational fluctuations of the internal combustion engine.

  As a conventional internal combustion engine control device, there has been proposed a device that calculates a rotation fluctuation rate based on a cycle deviation of the same segment of a rotation detection rotor in the case of continuous misfire and detects misfire by a rotation cycle for each ignition cycle. (For example, see Patent Document 1).

  Further, as another conventional device, a first time difference between the rotation time of the explosion stroke of the current control cylinder by the rotation angle of the current control cylinder and the rotation time of the explosion stroke of the next control cylinder is obtained, and the current explosion stroke is obtained. To obtain a second time difference between a rotation time of a position having a phase difference of 360 degrees from a rotation angle and a rotation time of a rotation angle of a position having a phase difference of 360 degrees from the next explosion stroke. One that detects misfire based on a time deviation from the second time difference has been proposed (see, for example, Patent Document 2).

As in Patent Documents 1 and 2, misfire detection based on the difference in the rotation cycle is effective for an internal combustion engine (engine) having an even number of cylinders.
That is, in an internal combustion engine with an even number of cylinders, the same segment of the rotation detection rotor is in the same stroke of the other cylinders, so that the misfire cylinder can be detected by directly comparing with other cylinders that have not misfired. Become.

On the other hand, in an internal combustion engine having an odd number of cylinders, the same segment of the rotation detection rotor is different from the stroke position of the other cylinder, and when misfire detection is performed in comparison with the same stroke of the other cylinder, Since the same segment cannot be used, a different part of the rotor for rotation detection is used.
Therefore, since the measurement cycle includes a variation error due to manufacturing tolerances, misfire detection may be reduced.

  In addition, in an internal combustion engine with an odd number of cylinders, when misfire detection is performed using the same segment of the rotation detection rotor, the other cylinders compared with the misfire cylinder are not in the same stroke as the misfire cylinder, and therefore the cycle May be different, and although there is no decrease in misfire detectability due to variations in the rotation detection rotor, misfire detectability may be deteriorated due to the different periods.

  Further, for example, when the misfire detection value is calculated based on the difference between the combustion stroke time and the intake stroke time, if the rotation detection rotor is disposed at different positions, the rotation detection rotor is disposed at different positions. Compared to the case where there is no rotation, the calculation result is different, and the compensation for the variation in the arrangement of the rotation detection rotor is insufficient.

Next, the difference in the difference calculation result with respect to the presence or absence of variation in the three-cylinder (# 1 to # 3) internal combustion engine will be specifically described with reference to the timing chart of FIG.
In FIG. 12, the upper side shows processing for the crank angle signal when there is no variation in the rotation detection rotor, and the lower side shows processing for the crank angle signal when there is variation in the rotation detection rotor. Yes.

In FIG. 12, each measurement time is based on the top dead center TDC of each cylinder, and specific numerical values of the crank angle [degCA] and the time [ms] are examples.
For example, on the lower side in FIG. 12, the arrangement position of the teeth used for the stroke time calculation of the rotation detection rotor varies by 10% (= 18 degrees) with respect to 180 degrees (180 [degCA]). Show.

The stroke of # 1 TDC shown at the left end in FIG. 12 is a misfire stroke, and the pulse interval of the crank angle signal is longer than in other strokes, and it takes time to rotate by the same crank angle.
First, when there is no variation in the rotation detection rotor (see the upper stage in FIG. 12), the current combustion stroke time Ta1 and the next combustion stroke time Ta2, the current intake stroke time Tb1 and the next intake stroke time. If the equation of Patent Document 2 is applied using Tb2, the time deviation ΔTA between the first time difference and the second time difference can be obtained from the following equation (1).

ΔTA = (Ta1-Ta2)-(Tb1-Tb2)
= (15 [ms] -10 [ms])-(10 [ms] -10 [ms])
= 5 [ms] (1)

The time deviation ΔTA obtained by the equation (1) is compared with a misfire determination value, and when the time deviation ΔTA is greater than or equal to the misfire determination value, it is determined that a misfire has occurred.
On the other hand, when there is a variation in the rotation detection rotor (see the lower stage in FIG. 12), the time deviation ΔTB is calculated based on the current combustion stroke time Ta1 ′, the next combustion stroke time Ta2, and the current intake stroke time Tb1. 'And the next intake stroke time Tb2 are obtained from the following equation (2).

ΔTB = (Ta1′−Ta2) − (Tb1′−Tb2)
= (12 [ms] -10 [ms])-(8 [ms] -10 [ms])
= 4 [ms] (2)

  As described above, the calculation results of the time deviations ΔTA and ΔTB differ depending on whether or not there is variation in the rotation detecting rotor, and there is a concern that misfire detection performance may be reduced due to the occurrence of variation.

JP-A-6-2609 JP 7-217488 A

As described above, since the conventional internal combustion engine control device detects misfire based on the period deviation, when the number of cylinders of the internal combustion engine is an odd number, the rotation detection rotor or the like includes a variation error. There was a problem that misfire detectability was lowered.
In addition, when the number of cylinders of the internal combustion engine is an odd number and misfire detection is performed using the same segment of the rotation detection rotor, the other cylinders to be compared with the misfire cylinder are not in the same stroke as the misfire cylinder. However, there is a problem that misfire detection is deteriorated due to different periods.
Further, when the difference between the combustion stroke time and the intake stroke time is calculated, the calculation result differs due to the variation in the arrangement position of the rotation detection rotor. There was a problem that it became insufficient and the misfire could not be detected accurately.

  The present invention has been made to solve the above-described problems, and is capable of detecting misfires with high accuracy without being affected by the variation even if there is a variation in the manufacture of the rotor for detecting rotation. An object is to obtain an engine control device.

  An internal combustion engine control apparatus according to the present invention includes a crank angle detection unit that is provided on a crankshaft of an internal combustion engine and generates a crank angle signal, and a crank corresponding to a combustion stroke corresponding to each cylinder of the internal combustion engine based on the crank angle signal. Combustion stroke time measuring means for determining the combustion stroke time required for the angular section, and intake stroke time measuring means for determining the intake stroke time required for the crank angle section corresponding to the intake stroke corresponding to each cylinder of the internal combustion engine based on the crank angle signal And misfire detection means for detecting misfire of the internal combustion engine based on the ratio of the combustion stroke time to the intake stroke time. The combustion stroke time measurement means and the intake stroke time measurement means use the same part of the crank angle signal. The combustion stroke time and the intake stroke time are measured.

  According to the present invention, even in an engine with an odd number of cylinders, misfire can be detected based on the ratio of the combustion stroke time and the intake stroke time, and without being affected by the manufacturing variation of the rotation detection rotor. Misfire can be detected with high accuracy.

Embodiment 1 FIG.
Hereinafter, the first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram conceptually showing the basic functional structure of the internal combustion engine control apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a block diagram showing the entire system of the internal combustion engine control apparatus according to the present invention.

In FIG. 1, a control unit (hereinafter referred to as “ECU”) 100, together with a crank angle detection means 101 and a load detection means 102 provided in an internal combustion engine (described later), constitutes a main part of the internal combustion engine control device. Yes.
The crank angle detection means 101 is provided on a crankshaft (not shown) of the internal combustion engine and generates a crank angle signal SGT. Moreover, the load detection means 102 produces | generates the intake pipe pressure Pb, for example as load information of an internal combustion engine.

  The ECU 100 includes a period measurement unit 103, a detection value calculation unit 104, a rotation speed calculation unit 105, a determination value calculation unit 106, a comparison unit 107, and a misfire detection unit 108, and includes a crank angle detection unit 101 and a load. Arithmetic processing using the detection signal from the detection means 102 as input information is executed.

Within the ECU 100, the cycle measuring means 103 includes a combustion stroke cycle (time) measuring means and an intake stroke cycle (time) measuring means based on the crank angle signal SGT, and the combustion stroke cycle using the same portion of the crank angle signal SGT. TCcyc (i) and the intake stroke period TIcyc (i) are measured.
The combustion stroke cycle TCcyc (i) indicates the combustion stroke time required for the crank angle section corresponding to the combustion stroke corresponding to each cylinder of the internal combustion engine, and the intake stroke cycle TIcyc (i) corresponds to each cylinder of the internal combustion engine. The intake stroke time required for the crank angle section corresponding to the intake stroke is shown. Hereinafter, the concept of various times will be described in terms of cycles.

The detection value calculation unit 104 calculates the time ratio of each stroke cycle calculated by the cycle measurement unit 103 as the cycle ratio K (i), and calculates the deviation of the cycle ratio deviation ΔK (i) as the misfire detection value Kkan (i). (I is a cycle number).
The rotational speed calculation means 105 calculates the engine rotational speed Ne based on the pulse period of the crank angle signal SGT.

Determination value calculation means 106 calculates misfire determination value Jkan by map calculation based on engine rotation speed Ne and intake pipe pressure Pb (engine load).
The comparison means 107 compares the misfire detection value Kkan (i) with the misfire determination value Jkan.
When the comparison result of the comparison unit 107 indicates Kkan (i)> Jkan, the misfire detection unit 108 detects a misfire state and outputs a detection result indicating the occurrence of misfire to an alarm unit or the like.

That is, the misfire detection means 108 in the ECU 100 measures the cycle variation of the internal combustion engine and detects misfire based on the cycle ratio K (i) between the combustion stroke cycle TCcyc (i) and the intake stroke cycle TIcyc (i). It is supposed to be.
The misfire detection means 108 may include the functions of the detection value calculation means 104 and the comparison means 107.

In FIG. 2, the internal combustion engine 200 is composed of, for example, a three-cylinder engine having an odd number of cylinders.
An intake pipe 203 of the internal combustion engine 200 includes an air cleaner 201 that purifies the air taken in by the internal combustion engine 200, an air flow sensor 202 that detects the intake air amount Qa of the internal combustion engine 200, and a throttle valve 204 that adjusts the intake air amount Qa. And a pressure sensor 205 for detecting the intake pipe pressure Pb, and an injector 206 for supplying fuel to the intake air of the internal combustion engine 200 to form an air-fuel mixture.

The pressure sensor 205 constitutes the load detection means 102 in FIG.
Although not shown in FIG. 2, the throttle valve 204 may be provided with a throttle opening sensor that detects the throttle opening.
Further, the load detecting means 102 is not limited to the pressure sensor 205, and for example, an air flow sensor 202 or a throttle opening sensor may be used.

On the other hand, in the exhaust pipe 207 of the internal combustion engine 200, an O2 sensor 208 that measures the amount of residual oxygen in the exhaust gas discharged from the internal combustion engine 200, and HC, CO, and NOx, which are harmful components of the exhaust gas, are harmless CO2 and A three-way catalyst 209 that converts to H2O is provided.
The internal combustion engine 200 is also provided with an ignition coil 210 that generates a high voltage at the secondary coil by energizing and shutting off the current through the primary coil, and generates a spark in the combustion chamber of the internal combustion engine 200 by the high voltage. A spark plug 211 is provided.

Further, the internal combustion engine 200 includes a cam angle sensor 212 that generates a cam angle signal SGC, a cam angle sensor plate 213 in which a protrusion or a depression for generating the cam angle signal SGC from the cam angle sensor 212 is formed, a crank A crank angle sensor 214 for generating an angle signal SGT, a crank angle sensor plate 215 formed with a protrusion or a recess for generating the crank angle signal SGT from the crank angle sensor 214, and a cooling water 216 for cooling the internal combustion engine 200, A water temperature sensor 217 for detecting the water temperature Wt of the cooling water 216 is provided.
The crank angle sensor 214 and the crank angle sensor plate (rotation detection rotor) 215 constitute the crank angle detection means 101 in FIG.

  ECU 100 detects detection signals (intake air amount Qa, intake pipe pressure Pb, residual oxygen) from various sensors (air flow sensor 202, pressure sensor 205, O2 sensor 208, cam angle sensor 212, crank angle sensor 214, water temperature sensor 217, etc.). The control amount (fuel injection amount, ignition timing, etc.) for various actuators (injector 206, ignition coil 210, etc.) of the internal combustion engine 200 is calculated using the amount, cam angle signal SGC, crank angle signal SGT, water temperature Wt, etc.) as input information. And output a control signal.

Next, a period measurement process using the crank angle sensor signal SGT and the cam angle sensor signal SGC according to Embodiment 1 of the present invention will be described with reference to the timing chart of FIG.
FIG. 3 shows a cycle measurement process when the number of cylinders of the internal combustion engine 200 is an odd number. The stroke of each cylinder (# 1 to # 3) of the three-cylinder engine and the output timing of the crank angle signal SGT and the cam angle signal SGC. Shows the relationship.

In FIG. 3, the crank angle signal SGT outputs a pulse signal every 10 degrees (10 [degCA]) in the crank angle.
Further, the crank angle sensor plate 215 is provided with a missing tooth portion so as not to output a pulse signal at a predetermined angular position (dotted line portion of SGT in FIG. 3).

In the missing tooth portion (predetermined angle position), the pulse signal of the crank angle signal SGT is missing in one tooth or two teeth continuously, so that the pulse signal interval of the missing tooth portion is one tooth missing. In the case of 20 degrees and 2 missing teeth, it is 30 degrees.
For example, the missing tooth position when one tooth is missing can be detected from satisfying the condition of the following expression (3).

{T (n-1) / T (n) + T (n-1) / T (n-2)} / 2 ≧ 1.5, and
{T (n-1) / T (n) + T (n-1) / T (n-2)} / 2 <2.5 (3)

  Further, the missing tooth position in the case of missing two teeth can be detected from satisfying the condition of the following expression (4).

  {T (n-1) / T (n) + T (n-1) / T (n-2)} / 2 ≧ 2.5 (4)

In Equations (3) and (4), T (n) is the time interval (current value) of the current crank angle signal SGT, and T (n-1) is the time interval of the previous crank angle signal SGT. (Previous value), and T (n−2) is the time interval (previous value) of the crank angle signal SGT of the previous time.
The crank angle position at the time of missing tooth detection is BTDC 75 degrees or ATDC 45 degrees of each cylinder.

  Here, if the number of pulses of the cam angle signal SGC between the missing teeth from the previous missing tooth detection to the current missing tooth detection is counted, the number of missing teeth (one or two teeth) this time and the missing teeth Based on the combination with the number of pulses of the cam angle signal SGC in the meantime, the current cylinder to be controlled and the crank angle position can be determined as follows.

That is, if the number of missing teeth is “2” and the number of pulses of the cam angle signal SGC between the missing teeth is “1”, it can be seen that the cylinder is B75 degrees of # 1 cylinder.
Further, if the number of missing teeth is “1” and the number of pulses of the cam angle signal SGC between missing teeth is “2”, it can be seen that the B3 degree of the # 3 cylinder is B75 degrees.
Further, if the number of missing teeth is “1” and the number of pulses of the cam angle signal SGC between missing teeth is “1”, it is understood that the B2 degree of the # 2 cylinder is B75 degrees.
Furthermore, when the number of pulses of the cam angle signal SGC between the missing teeth is “0”, it is understood that the angle is 45 degrees for each cylinder.

As described above, if the cylinder and the crank angle position can be specified, the crank number CRKno can be added to each crank angle signal SGT, and the crank angle signal SGT can be specified.
FIG. 3 shows a case where the crank number CRKno is incremented sequentially to “71” with the B5 degree of the # 1 cylinder being “0”, and returns to “0” again. Can be identified.

  In the case of missing one tooth at the time of missing tooth detection, for example, as shown in the transition from “CRKno = 51” to “CRKno = 53” in FIG. In the case of two missing teeth, for example, as shown in the transition from “CRKno = 62” to “CRKno = 65” in FIG. 3, an extra “2” is added.

Next, the intake stroke time TIcyc (i) and the combustion stroke time TCcyc (i) according to the first embodiment of the present invention are calculated with reference to the flowcharts of FIGS. 4 and 5 together with FIG. 3 and the explanatory view of FIG. The operation will be described.
The processing routines of FIGS. 4 and 5 are executed each time the crank angle signal SGT is input.
4 and 5, a timer counter for measuring the period and a cylinder counter for determining the cylinder are provided, the timer value TM is up-counted as time elapses, and the cylinder counter value N is processed as shown in FIG. Is counted up each time.

In FIG. 4, first, the cylinder counter value N is initially set to “1” (step 401), and the reading process of the timer value TM is executed (step 402).
Details of the timer value TM reading process (step 402) will be described later with reference to FIG.
Next, the cylinder counter value N is incremented by “1” (step 403), and it is determined whether or not the cylinder counter value N is “3” or less (step 404).

If it is determined in step 404 that N ≦ 3 (that is, YES), the process returns to step 402 and the timer value TM reading process is repeatedly executed.
On the other hand, if it is determined in step 404 that N> 3 (that is, NO), the processing routine of FIG. 4 is terminated.

The comparison reference value “3” at step 404 corresponds to the number of cylinders of the internal combustion engine 200.
Here, since a three-cylinder engine is taken as an example, the comparison reference value (= the number of cylinders) in step 404 is set to “3”, but is set to a value corresponding to the number of cylinders and is a five-cylinder engine. The comparison reference value is “5”.

FIG. 5 shows the timer value reading process (step 402) in FIG. 4 in detail.
Note that the counting process of the crank number CRKno is executed by a separate routine (not shown), and it is assumed that the crank number CRKno is specified when the process of FIG. 5 is executed.
In FIG. 5, first, the ECU 100 compares the crank number CRKno with the start point COM_S (N) of the combustion stroke cycle TCcyc (i), and determines whether or not CRKno = COM_S (N) (step 405). ).

Note that the start point COM_S (N) of the combustion stroke cycle TCcyc (i) is represented by an array according to the cylinder counter value N, and is the cycle measurement crank angle section (hereinafter referred to as “cycle measurement section”) shown in FIG. Taking the case as an example, the table is defined as shown in FIG.
The crank number CRKno of the start point COM_S of the combustion stroke cycle TCcyc (i) of each cylinder (cylinder counter value N = 1, 2, 3) is preset as shown in FIG. 6, for example.

If it is determined in step 405 that CRKno = COM_S (N) (that is, YES), the timer value TM is acquired as the combustion stroke start time TCS (N) (step 406), and the next determination process (step 407) is performed. move on.
The timer value TM is a free-run counter value, and is a value holding the time when the processing of FIG. 4 is started (that is, when the crank angle signal SGT is input).

On the other hand, if it is determined in step 405 that CRKno ≠ COM_S (N) (that is, NO), the process proceeds to step 407 without executing step 406.
In step 407, the crank number CRKno is compared with the end point COM_E (N) of the combustion stroke cycle TCcyc (i), and it is determined whether or not CRKno = COM_E (N).
The end point COM_E (N) of the combustion stroke cycle TCcyc (i) is represented by the same arrangement as the start point COM_S (N). Taking the case of the cycle measurement section of FIG. 3 as an example, The crank number CRKno of the end point COM_E of the combustion stroke cycle TCcyc (i) of each cylinder is set in advance.

If it is determined in step 407 that CRKno = COM_E (N) (that is, YES), the timer value TM is acquired as the combustion stroke end time TCE (N) (step 408), and the next determination process (step 409) is performed. move on.
The timer value TM is a free-run counter value as described above, and represents the time when the processing of FIG. 4 is started (that is, when the crank angle signal SGT is input).

On the other hand, if it is determined in step 407 that CRKno ≠ COM_E (N) (that is, NO), the process proceeds to step 409 without executing step 408.
In step 409, the crank number CRKno is compared with the starting point INT_S (N) of the intake stroke period TIcyc (i), and it is determined whether or not CRKno = INT_S (N).
The starting point INT_S (N) of the intake stroke cycle TIcyc (i) is arranged in the same manner as described above. In the case of the cycle measurement section of FIG. 3, the intake stroke cycle TIcyc of each cylinder defined as shown in FIG. The crank number CRKno of the starting point INT_S of (i) is set in advance.

If it is determined in step 409 that CRKno = INT_S (N) (that is, YES), the timer value TM is acquired as the intake stroke start time TIS (N) (step 410), and the next determination process (step 411) is performed. move on.
On the other hand, if it is determined in step 409 that CRKno ≠ INT_S (N) (that is, NO), the process proceeds to step 411 without executing step 410.

In step 411, the crank number CRKno is compared with the end point INT_E (N) of the intake stroke period TIcyc (i) to determine whether CRKno = INT_E (N).
The end point INT_E (N) of the intake stroke cycle TIcyc (i) has the same arrangement as described above. In the case of the cycle measurement section of FIG. 3, the intake stroke cycle TIcyc ( The crank number CRKno of the end point INT_E of i) is set in advance.

If it is determined in step 411 that CRKno = INT_E (N) (that is, YES), the timer value TM is acquired as the intake stroke end time TCE (N) (step 412), and the processing routine of FIG.
On the other hand, if it is determined in step 411 that CRKno ≠ INT_E (N) (that is, NO), the processing routine of FIG. 5 is terminated without executing step 411.

Next, specific misfire determination processing of ECU 100 according to Embodiment 1 of the present invention will be described with reference to the flowchart of FIG. 7 together with FIGS.
In the processing routine of FIG. 7, every time a crank angle signal SGT of B5 degrees [degCA] corresponding to the crank angle position immediately before TDC of each cylinder # 1 to # 3 (cylinder numbers n = 1, 2, 3) is input. To be executed.

In FIG. 7, first, the cycle measuring means 103 subtracts the combustion stroke start time TCS (n) from the combustion stroke end time TCE (n) to obtain a combustion stroke cycle TCcyc (i) (= TCE (n) −TCS ( n)) is calculated (step 501).
In the period measurement section shown in FIG. 3, in order to calculate the combustion stroke cycle TCcyc (2) and the intake stroke cycle TIcyc (2) of the # 2 cylinder at B5 degree of the # 1 cylinder, “n = 2” is set. Set.
In addition, in order to calculate the combustion stroke cycle TCcyc (3) and the intake stroke cycle TIcyc (3) of the # 3 cylinder at the B5 degree of the # 2 cylinder, “n = 3” is set. Is set to “n = 1” in order to calculate the combustion stroke cycle TCcyc (1) and the intake stroke cycle TIcyc (1) of the # 1 cylinder.

  When the end point COM_E (n) of the combustion stroke cycle TCcyc (i) is set to be retarded from the next B5 degrees (for example, the # 1 cylinder in FIG. 3 and the crank number CRKno = 25), each cylinder The crank number CRKno (cylinder number n) is delayed by one stroke from the above, “n = 3” when the cylinder # 1 is B5 degrees, “n = 1” when the cylinder # 2 is B5 degrees, # “N = 2” at B5 of 3 cylinders.

3 is set in advance, and the cylinder number n is also specified.
In addition, as will be described later, even if the cycle measurement section is changed according to the operating state, the cylinder number n is appropriately set according to the set measurement cycle.
Further, regarding the cycle number i, regardless of the cylinder, the current value is “i”, the previous value (if the ignition order is # 1 → # 3 → # 2, if the current is the # 1 cylinder, the # 2 cylinder ) Becomes “i−1”.

Subsequently, the cycle measuring means 103 subtracts the intake stroke start time TIS (n) from the intake stroke end time TIE (n) to obtain the intake stroke cycle TIcyc (i) (= TIE (n) −TIS (n)). Is calculated (step 502).
Next, the detected value calculation means 104 divides the combustion stroke cycle TCcyc (i) by the intake stroke cycle TIcyc (i) to calculate a cycle ratio K (i) (= TCcyc (i) / TIcyc (i)). (Step 503).

  At this time, the use of the cycle ratio K (i) between the combustion stroke cycle TCcyc (i) and the intake stroke cycle TIcyc (i) causes variations in the arrangement positions of the teeth of the crank angle signal plate 215, so that each cylinder Even if each stroke cycle is different, the influence of variation can be eliminated.

Subsequently, the detected value calculation means 104 subtracts the previous cycle ratio K (i−1) from the current cycle ratio K (i) to obtain a cycle ratio deviation ΔK (i) (= K (i) −K (i−1). )) Is calculated (step 504).
Further, the detection value calculation means 104 subtracts the current cycle ratio deviation ΔK (i) from the previous cycle ratio deviation ΔK (i−1), and detects the misfire detection value Kkan (i) consisting of the deviation of the cycle ratio deviation ΔK (i). (= ΔK (i−1) −ΔK (i)) is calculated (step 505).

On the other hand, the determination value calculation means 106 calculates the misfire determination value Jkan by interpolating the misfire determination map MAP from the engine speed Ne and the intake pipe pressure Pb (step 506).
The misfire determination map MAP is adapted in advance by experiments.
Next, the comparison means 107 compares the misfire detection value Kkan (i) with the misfire determination value Jkan, and determines whether or not the relationship of Kkan (i)> Jkan is satisfied (step 507).

If it is determined in step 507 that Kkan (i)> Jkan (that is, YES), the misfire determination flag MISF (m) for cylinder number m is set to “1” (step 508), and the processing routine of FIG. Exit.
On the other hand, if it is determined in step 507 that Kkan (i) ≦ Jkan (that is, NO), the misfire determination flag MISF (m) is cleared to “0” (step 509), and the processing routine of FIG. To do.

In step 505 by the detection value calculation means 104, the misfire detection value Kkan (i) is obtained by subtracting the current cycle ratio deviation ΔK (i) from the previous cycle ratio deviation ΔK (i−1). The increase timing of the misfire detection value Kkan (i) at that time is delayed by one ignition from the cylinder number n.
Therefore, the cylinder number m in the misfire determination flag MISF (m) is “m = 2” when n = 1, “m = 3” when n = 2, and n = When m is 3, “m = 1”.

For example, when the # 1 cylinder misfires, as shown by the solid line waveform in FIG. 3, the cycle time of the # 1 cylinder becomes longer than when the misfire does not occur (see the broken line waveform), and the combustion stroke cycle TCcyc. (1) is longer than the intake stroke period TIcyc (1).
Therefore, the misfire of the # 1 cylinder can be detected by executing the flowchart of FIG. 7 (misfire determination process).

Next, a specific operation when the control processing of FIGS. 4, 5, and 7 is executed will be described with reference to the timing chart of FIG.
In FIG. 8, the horizontal axis indicates the number of ignitions (the number of ignition cycles), and the vertical axis indicates, from the upper side, the period time [s], the period ratio K (i), the period ratio deviation ΔK (i), and misfire detection. The change of the value Kkan (i) for each ignition cycle is shown.

In the cycle time in FIG. 8, the value indicated by “black diamond dots” corresponds to the combustion stroke cycle TCcyc (i), and the value indicated by “black square dots” corresponds to the intake stroke cycle TIcyc (i).
In FIG. 8, the combustion stroke cycle TCcyc (i) of the ignition cycle “22nd cycle” in which misfire has occurred becomes longer than the intake stroke cycle TIcyc (i).
Thereby, the period ratio K (i) and the period ratio deviation ΔK (i) in the “22nd cycle” increase.

On the other hand, the misfire detection value Kkan (i) (see the lowest stage in FIG. 8) increases at the “23rd cycle” delayed by one ignition cycle.
Therefore, by comparing the misfire detection value Kkan (i) at the “23rd cycle” with the misfire determination value Jkan, misfire can be detected from Kkan (i)> Jkan.

  Thereafter, the number of times that the misfire determination flag MISF (m) is set to “1” for each predetermined number of times of ignition is counted, and when the number of times the flag is set exceeds a predetermined value, for example, an indicator lamp is turned on to generate misfire. Inform the driver of the condition.

  Thus, in the internal combustion engine control apparatus that measures each stroke cycle based on the crank angle signal SGT and detects the occurrence of misfire based on the cycle variation, the cycle measuring unit 103 including the combustion stroke cycle measuring unit and the intake stroke cycle measuring unit. And misfire detecting means 108 for detecting misfire of the internal combustion engine 200 based on the cycle ratio K (i), and the cycle measuring means 103 uses the same portion of the crank angle signal SGT to perform the combustion stroke cycle TCcyc (i). And the intake stroke cycle TIcyc (i) is measured, and the detected value calculation means 104 is based on a cycle ratio K (i) between the combustion stroke cycle TCcyc (i) and the intake stroke cycle TIcyc (i) one rotation before. The misfire detection value Kkan (i) is calculated.

  Thereby, in misfire detection based on the cycle ratio K (i), even if the arrangement positions of the teeth of the crank angle signal plate 215 (rotation detection rotor) for measuring each stroke cycle vary, a stable cycle Since the ratio calculation result is obtained, misfire can be detected without impairing misfire detectability.

Here, in order to clarify the difference between the first embodiment of the present invention and the conventional apparatus, the above effect will be described with reference to FIG.
For example, in FIG. 12, when calculating the detection value based only on the deviation as in the conventional apparatus, a difference occurs depending on the presence or absence of variation as in the above-described formulas (1) and (2). When the misfire detection value Kkan (i) based on the ratio is calculated as in the invention, there is no difference depending on the presence or absence of variation.

  That is, in FIG. 12, the cycle ratio KA (i) between the combustion stroke time Ta1 and the intake stroke time Tb1 when there is no variation is expressed as the following equation (5).

KA (i) = Ta1 / Tb1
= 15 [ms] / 10 [ms]
= 1.5 (5)

  In addition, the period ratio KA (i) ′ between the combustion stroke time Ta1 ′ and the intake stroke time Tb1 ′ when there is a variation is expressed by the following equation (6).

KA (i) ′ = Ta1 ′ / Tb1 ′
= 12 [ms] / 8 [ms]
= 1.5 (6)

  Therefore, it can be seen that the misfire detection value Kkan (i) based on the cycle ratio K (i) is not affected by variations in the crank angle signal plate 215 (rotation detection rotor).

Further, even when the number of cylinders of the internal combustion engine 200 is an odd number, misfire can be detected based on the cycle ratio K (i) between the combustion stroke cycle TCcyc (i) and the intake stroke cycle TIcyc (i). It is possible to detect misfire with high accuracy without being affected by the above.
Therefore, the misfire occurrence state can be accurately communicated to the driver, and the driver can be encouraged to take measures to prevent the exhaust gas deterioration of the internal combustion engine 200 and the three-way catalyst 209 from deteriorating due to the misfire occurrence.

  Even if there is a variation in the crank angle signal plate 215, the calculated value of the cycle ratio K (i) is stable with almost no change, so that misfire detection can be ensured and no misfire has occurred. Since the misfire determination value Jkan having a margin can be set, it is possible to avoid and reduce false detection caused by periodic fluctuations caused by disturbances when traveling on rough roads and improve false detection resistance.

Further, since the calculation value of the cycle ratio K (i) is stable with respect to the variation of the crank angle signal plate 215, the standard crank angle signal plate is used when the calculation map for the misfire determination value Jkan is applied. It only needs to be adapted using 215.
In addition, in the conventional apparatus, it was necessary to check and review the variation product after conforming with the standard crank angle signal plate 215. According to the present invention, the manufacturing variation of the crank angle signal plate 215 is required. However, since the misfire detection value Kkan (i) does not change, the work of adapting the misfire determination value Jkan becomes unnecessary, and the number of adaptation man-hours can be reduced as compared with the conventional apparatus.

  Further, the detection value calculation means 104, the comparison means 107, and the misfire detection means 108 calculate the difference of the cycle ratio K (i) as the cycle ratio deviation ΔK (i) (time ratio deviation) and the cycle ratio deviation ΔK (i ) As a misfire detection value Kkan (i), and the misfire detection value Kkan (i) is compared with a preset misfire determination value Jkan to detect misfire of the internal combustion engine 200. Therefore, the period ratio deviation ΔK (i The misfire detection value Kkan (i) based on the difference of) makes it possible to clarify the difference between when a misfire occurs and when it does not occur, and further improve the misfire detection performance.

Embodiment 2. FIG.
In the first embodiment (see FIG. 7), the correction process in the calculation (steps 501 and 502) of the combustion stroke cycle TCcyc (i) and the intake stroke cycle TIcyc (i) has not been mentioned. It may be corrected so that each stroke cycle in a state where no misfire has occurred has substantially the same value.
FIG. 9 is a flowchart showing misfire determination processing according to Embodiment 2 of the present invention in which correction processing (step 502A) is provided.

9, the same processes as those described above (see FIG. 7) are denoted by the same reference numerals as those described above, and detailed description thereof is omitted.
Further, the functional configuration of the ECU 100 and the overall configuration of the apparatus are as shown in FIGS. 1 and 2, and the basic processing operation is as shown in FIGS.

In this case, the cycle measuring means 103 calculates the intake stroke cycle TIcyc (i) (step 502A) following the calculation of the combustion stroke cycle TCcyc (i) (step 501). At this time, the intake stroke cycle TIcyc ( A correction operation is added to i).
That is, the difference between the intake stroke end time TIE (n) and the intake stroke start time TIS (n) is multiplied by the coefficient K, and the intake stroke cycle TIcyc (i) is calculated as shown in Equation (7) below.

  TIcyc (i) = {TIE (n) −TIS (n)} × K (7)

For example, in the state where no misfire has occurred in FIG. 3, the intake stroke cycle TIcyc (i) is longer than the combustion stroke cycle TCcyc (i) (as indicated by the one-dot chain line in FIG. 3). The average value of the cycle time is large).
Therefore, in order to cope with such a case, the coefficient K by which the intake stroke period TIcyc (i) is multiplied is set to a value smaller than “1.0”.

However, depending on the setting of the measurement cycle interval, the combustion stroke cycle TCcyc (i) may be larger than the intake stroke cycle TIcyc (i), contrary to the case of FIG. K is set to a value of “1.0” or more.
That is, the coefficient K is set so that the combustion stroke cycle TCcyc (i) and the intake stroke cycle TIcyc (i) in a state where no misfire has occurred are substantially the same value.

Further, in FIG. 9, correction processing by multiplication of the coefficient K is added in the calculation of the intake stroke cycle TIcyc (i) (step 502A), but the correction processing is performed in the calculation of the combustion stroke cycle TCcyc (i) (step 501). May be added.
Further, correction processing may be added in calculating both the combustion stroke cycle TCcyc (i) and the intake stroke cycle TIcyc (i).
That is, the combustion stroke cycle TCcyc (i) or the intake stroke cycle TIcyc (i) is a deviation between the combustion stroke cycle TCcyc (i) and the intake stroke cycle TIcyc (i) in a state where no misfire has occurred in the internal combustion engine 200. It suffices to correct so as to be eliminated.

  In this way, when there is a deviation in each value of the combustion stroke cycle TCcyc (i) and the intake stroke cycle TIcyc (i) in a state where no misfire has occurred, the coefficient K is used so that the values are substantially equal. Since the value of the period ratio K (i) in a state where no misfire has occurred can be maintained at substantially “1”, the misfire detection performance is improved by clarifying the difference from the occurrence of misfire. be able to.

That is, a state in which no misfire has occurred by correcting each cycle time of the combustion stroke cycle TCcyc (i) and the intake stroke cycle TIcyc (i) in a state where no misfire has occurred, so as to be excluded from being different from each other. Since the difference in the engine cycle position of each stroke cycle in can be compensated, misfire detection can be further improved.
The coefficient K may be set to a predetermined value in advance, but may be set to a value learned for each operation point in a state where no misfire has occurred. Further improvement can be achieved.

Embodiment 3 FIG.
In the first and second embodiments, the optimum cycle measurement position is not mentioned, but as shown in FIG. 10, depending on the operating state of the internal combustion engine 200 (engine rotational speed Ne, intake pipe pressure Pb). The measurement position of each stroke cycle for misfire detection may be variably set.
FIG. 10 is an explanatory diagram showing the setting process of the periodic measurement position according to the third embodiment of the present invention, and shows map data of the optimal periodic measurement position according to the operating state of the internal combustion engine 200.

  In this case, the cycle measuring means 103 in the ECU 100 has the map data shown in FIG. 10, and a crank angle section (cycle measuring position) measured by the combustion stroke cycle measuring means and the intake stroke cycle measuring means in the cycle measuring means 103 is used. ) Is changed according to the operating state of the internal combustion engine 200.

Each numerical value shown in FIG. 10 indicates the amount of retardation of the measurement start point in each stroke cycle when the crank angle position B5 degrees is used as the reference position.
Therefore, for example, in the case of 70 degrees [degCA], the angle position is delayed by 70 degrees from B5 degrees, and the measurement start point by the period measuring unit 103 is the crank angle position A65 degrees.

In FIG. 10, the crank angle section measured by the period measuring means 103 is changed to the advance side as the engine speed Ne is lower (the internal combustion engine 200 is rotating at a lower speed), and the delay amount of the period measurement start point is 130. [DegCA] → 110 [degCA] → 90 [degCA] → 70 [degCA].
Conversely, the higher the engine speed Ne (the higher the internal combustion engine 200 is), the more the measured crank angle section is changed to the retard side, and the retard amount at the period measurement start point is 70 [degCA] → 90 [ degCA] → 110 [degCA] → 130 [degCA].

  Further, the crank angle section measured by the period measuring means 103 is changed to an advanced side as the intake pipe pressure Pb is high (close to atmospheric pressure) and the internal combustion engine 200 is heavily loaded. When the internal combustion engine 200 is under a low load in a negative pressure state where Pb is low (close to vacuum), the retarded angle is changed.

Further, the amount of change in the crank angle position per time increases as the internal combustion engine 200 rotates at a higher speed.
On the other hand, since the combustion speed of the internal combustion engine 200 is the same as long as the intake air amount Qa is the same, the influence of misfire of the internal combustion engine 200 appears on the retard side of the crank angle position as the engine speed Ne increases. Therefore, it can be seen that the misfire detection performance is improved by setting the period measurement section to the retard side as the internal combustion engine 200 rotates at a higher speed.

  Therefore, as shown in FIG. 10, the misfire detection value at the time of misfiring occurs compared with the non-firing occurrence by changing the cycle measurement start point by the cycle measuring means 103 to the retard side as the engine rotational speed Ne is higher. Since Kkan (i) has a large value, misfire detection can be further improved.

On the other hand, regarding the load of the internal combustion engine 200, the combustion speed increases as the intake air amount Qa increases, and the combustion speed decreases as the intake air amount Qa decreases. Therefore, periodic measurement starts as the intake pipe pressure Pb (load) decreases. It can be seen that if the point is retarded, the misfire detection performance is improved.
Therefore, as shown in FIG. 10, the misfire detection performance can be improved by changing and setting the cycle measurement start point to the retard side as the intake pipe pressure Pb (load of the internal combustion engine 200) is lower.

  In FIG. 10, the cycle measurement start point is changed and set according to the operating state of the internal combustion engine 200, but not only the cycle measurement start point is advanced or retarded, but the cycle measurement range (section) is expanded or It may be reduced.

In this way, by changing the crank angle cycle measurement interval for misfire detection according to the operating state of the internal combustion engine 200, an appropriate cycle measurement interval in each operating state can be set, and misfire detectability can be improved. Can be improved.
In addition, the occurrence of cycle fluctuations when a misfire occurs changes depending on the operating state, and by setting an appropriate timing, the misfire detection performance is further improved and the operating state in which misfire detection is possible is expanded. be able to.

Specifically, the measured crank angle section of each stroke cycle is advanced as the internal combustion engine 200 is rotated at a low speed and retarded as the engine is rotated at a high speed, thereby changing the cycle at the time of occurrence of misfire that varies depending on each operation state. It is possible to accurately select the location where the fluctuation occurs.
In addition, by delaying the measured crank angle section of each stroke cycle as the internal combustion engine 200 is lightly loaded and advancing as the load is high, the cycle fluctuation occurrence portion at the time of occurrence of misfire that changes depending on each operation state Can be selected accurately.

Embodiment 4 FIG.
In the first to third embodiments, the case where the period ratio deviation ΔK (i) has a negative value is not considered. However, when the period ratio deviation ΔK (i) has a negative value, It may be fixedly set to “0”.
FIG. 11 is a flowchart showing a misfire determination process according to the fourth embodiment of the present invention in which a process (step 504A) for setting the period ratio deviation ΔK (i) to a value of 0 or more is provided.

In FIG. 11, the same processes as those described above (see FIG. 7) are denoted by the same reference numerals as those described above, and detailed description thereof is omitted.
Further, the functional configuration of the ECU 100 and the overall configuration of the apparatus are as shown in FIGS. 1 and 2, and the basic processing operation is as shown in FIGS.

In this case, the detection value calculation unit 104 calculates the cycle ratio based on the difference between the current cycle ratio K (i) and the previous cycle ratio K (i−1) following the calculation of the cycle ratio K (i) (step 503). Deviation ΔK (i) is calculated (step 504A). At this time, the difference between the current cycle ratio K (i) and the previous cycle ratio K (i−1) is compared with “0”, and the larger value is calculated. The period ratio deviation ΔK (i) is assumed.
That is, if the difference between the current cycle ratio K (i) and the previous cycle ratio K (i−1) is less than 0 (negative value), the cycle ratio deviation ΔK (i) is fixedly set to “0”.

In this way, by setting the cycle ratio deviation ΔK (i) to a value of 0 or more, it is possible to prevent the cycle variation due to the backlash after the misfire has occurred from being erroneously determined as misfire, and the misfire detectability can be improved. Further improvement can be achieved.
That is, in the process of calculating the period ratio deviation ΔK (i), the value on the shortening side of the period ratio deviation ΔK (i) is limited to 0 or more, and the period ratio deviation ΔK (i) increases from the state where the period ratio deviation ΔK (i) increases when a misfire occurs. By limiting the side where the cycle ratio deviation ΔK (i) during normal combustion in the stroke becomes small, misfires are caused due to rotational fluctuations caused by rolling back after the occurrence of misfiring, particularly in the low speed operation region of the internal combustion engine 200. It is possible to prevent a misfire misdetection by calculating a calculation value close to the misfire state despite not being.

It should be noted that whether or not the restriction process (step 504A) on the shortening side of the period ratio deviation ΔK (i) added when calculating the period ratio deviation ΔK (i) is switched according to the operating state of the internal combustion engine 200 is switched. You may do it.
For example, the control based on the above limit process (step 504A) is performed only at the operation point where the influence of turning back due to misfire becomes large in an operation state (such as a low rotation region or a low load region) in which the rotation fluctuation after occurrence of misfire increases. It is conceivable that the control based on the restriction process is not executed at the other operation points by executing the difference between the ratio K (i) and “0”, whichever is greater.

In this way, by switching whether or not to execute the restriction processing on the shortening side of the cycle ratio deviation ΔK (i) when calculating the cycle ratio deviation ΔK (i) according to the operating state of the internal combustion engine, it is caused by the backlash due to misfire. It can be limited only to the operation region where the rotational fluctuation occurs.
That is, in other operation regions where no rebound occurs, if the restriction processing on the shortening side of the cycle ratio deviation ΔK (i) is executed, the misfire detection performance is lowered, so that the restriction process is performed in the operation region where no rebound occurs. By not executing the above, it is possible to prevent a decrease in the misfire detection rate.
Therefore, the calculation of the cycle ratio deviation ΔK (i) suitable for each operation point can be executed, and the misfire detection performance can be further improved.

  In the first to fourth embodiments described above, the case where the number of cylinders of the internal combustion engine 200 is an odd number has been described. However, the present invention can be applied even when the number of cylinders of the internal combustion engine 200 is an even number, and the same effect can be obtained. It goes without saying that it can be played.

It is a block diagram which shows roughly the function of the principal part of the internal combustion engine control apparatus which concerns on Embodiment 1 of this invention. 1 is a configuration diagram illustrating an entire system of an internal combustion engine control apparatus according to Embodiment 1 of the present invention. FIG. It is a timing chart which shows the period measurement process by Embodiment 1 of this invention. It is a flowchart which shows the period measurement process by Embodiment 1 of this invention. It is a flowchart which shows the period measurement process by Embodiment 1 of this invention. It is explanatory drawing which shows the period measurement process by Embodiment 1 of this invention. It is a flowchart which shows the misfire determination process by Embodiment 1 of this invention. It is explanatory drawing which shows concretely the misfire determination process by Embodiment 1 of this invention. It is a flowchart which shows the misfire determination process by Embodiment 2 of this invention. It is explanatory drawing which shows the period measurement timing by Embodiment 3 of this invention. It is a flowchart which shows the misfire determination process by Embodiment 4 of this invention. It is a timing chart for demonstrating the subject in a conventional apparatus.

Explanation of symbols

  100 ECU (control unit) 101 Crank angle detection means 102 Load detection means 103 Period measurement means 104 Detection value calculation means 105 Rotational speed calculation means 106 Determination value calculation means 107 Comparison means 108 Misfire detection means 200 internal combustion engine (engine), 201 air cleaner, 202 air flow sensor, 203 intake pipe, 204 throttle valve, 205 pressure sensor, 206 injector, 207 exhaust pipe, 208 O2 sensor, 209 three-way catalyst, 210 ignition coil, 211 spark plug, 212 Cam angle sensor, 213 Cam angle sensor plate, 214 Crank angle sensor, 215 Crank angle sensor plate, 216 Cooling water, 217 Water temperature sensor, Jkan misfire judgment value, Kkan (i) Misfire detection value, Ne Engine rotational speed, Pb intake pipe pressure (load), Qa intake air amount, SGT crank angle signal, TCcyc (i) combustion stroke cycle (combustion stroke time), TIcyc (i) the intake stroke period (intake stroke time).

Claims (9)

Crank angle detection means provided on the crankshaft of the internal combustion engine for generating a crank angle signal;
A combustion stroke time measuring means for obtaining a combustion stroke time required for a crank angle section corresponding to a combustion stroke corresponding to each cylinder of the internal combustion engine based on the crank angle signal;
An intake stroke time measuring means for obtaining an intake stroke time required for a crank angle section corresponding to an intake stroke corresponding to each cylinder of the internal combustion engine based on the crank angle signal;
Misfire detection means for detecting misfire of the internal combustion engine based on a ratio of the combustion stroke time to the intake stroke time;
The internal combustion engine control apparatus, wherein the combustion stroke time measuring means and the intake stroke time measuring means measure the combustion stroke time and the intake stroke time using the same portion of the crank angle signal.   The misfire detection means calculates the difference of the ratio as a time ratio deviation, further determines the difference of the time ratio deviation, and compares the difference of the time ratio deviation with a predetermined determination value, thereby The internal combustion engine control device according to claim 1, wherein misfire is detected.   The combustion stroke time or the intake stroke time is corrected so that a deviation between the combustion stroke time and the intake stroke time is eliminated in a state where no misfire has occurred in the internal combustion engine. The internal combustion engine control device according to claim 1.   2. The internal combustion engine controller according to claim 1, wherein the crank angle section measured by the combustion stroke time measuring unit and the intake stroke time measuring unit is changed according to an operating state of the internal combustion engine.   The crank angle section measured by the combustion stroke time measuring means and the intake stroke time measuring means is changed to the advanced angle side as the internal combustion engine is rotated at a low speed, and is changed to the retarded angle side as the internal combustion engine is operated at a high speed. The internal combustion engine control device according to claim 4, wherein the control device is an internal combustion engine control device.   The crank angle section measured by the combustion stroke time measuring means and the intake stroke time measuring means is changed to the retard side as the internal combustion engine is at a low load, and is changed to the advance side as the internal combustion engine is at a high load. The internal combustion engine control device according to claim 4, wherein the control device is an internal combustion engine control device.   The internal combustion engine control device according to claim 2, wherein, in the process of calculating the time ratio deviation, a value on the shortening side of the time ratio deviation is limited.   8. The internal combustion engine control device according to claim 7, wherein whether or not execution of the restriction processing on the shortening side of the time ratio deviation at the time of calculating the time ratio deviation is switched according to an operating state of the internal combustion engine. .   The internal combustion engine control device according to any one of claims 1 to 8, wherein the number of cylinders of the internal combustion engine is an odd number.

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