JPS6255464A - Controlling device for internal combustion engine - Google Patents

Abstract

PURPOSE:To avoid the reduction of a generated torque while restraining occurrence of knocking by controlling the ignition timing based on representative output values of a cylinder and knocking, both of which are detected by combustion pressure oscillations, and also on judgements being made whether abnormalities are occurred or not therein. CONSTITUTION:Combustion pressure oscillations of an engine are detected by a detecting means A, then based on this result, both a representative output value of a cylinder and a representative output value of knocking are detected. And said representative output values of the cylinder and knocking are judged whether abnormalities are occurred or not by a first judging means C and second judging means D respectively. And then an ignition timing is controlled by an ignition timing control means E based on both the judgement and the result detected by the detecting means B. Accordingly, at the occurrence of abnormality in detecting the representative output value of the cylinder, the ignition timing is controlled only by the representative output value of knocking, while, at the occurrence of abnormality in detecting the representative output value of knocking, the ignition timing is controlled in the same way as the control of the other normal cylinders. Thus, it is possible to avoid such troubles as a reduction of generated torque, a deterioration of fuel consumption, and an increase in exhaust gas temperature while restaining the occurrence of knocking.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for controlling ignition timing.

[Conventional technology]

Conventionally, as an ignition timing control device that controls the ignition timing of an internal combustion engine, for example, a cylinder pressure sensor (combustion pressure vibration sensor) that detects the cylinder pressure of the engine is provided for each cylinder, and the knocking vibration frequency is detected from the detection signal of this cylinder pressure sensor. The signal components in the band are separated and extracted, and the value obtained by integrating this extracted signal over the compression stroke of the internal combustion engine is taken as the cylinder's representative output value (B), and the value integrated over the explosion stroke is taken as the knock representative output value (K). So that their ratio (K/B) becomes a predetermined target value.

There is a system that corrects and controls the ignition timing for each cylinder (Japanese Patent Laid-Open No. 5
9-116030).

In other words, in an engine, the vibration component in the knocking vibration frequency band during the compression stroke does not change even if knocking occurs, whereas the vibration component in the knocking vibration frequency band during the explosion stroke increases due to the occurrence of knocking, and the knocking intensity increases. There is strong vibration.

Therefore, the components in the knocking vibration frequency band are separated and extracted from the engine cylinder pressure, integrated in the compression stroke and the explosion stroke, respectively, and the representative output value of the cylinder in the section unrelated to knocking (
B) and a representative knock output value (K) corresponding to the knocking intensity are detected, and the ignition timing is controlled for each cylinder so that the frequency of this ratio (K/B) exceeding a predetermined target value is constant. The engine is designed to avoid non-king without reducing the output of the internal combustion engine.

[Problem that the invention is trying to solve] However,
In such an internal combustion engine control device, a representative output value (B) of a cylinder, which is an integral value of a compression stroke, is used to control the ignition timing.

Therefore, when the integrator malfunctions or when abnormal vibration occurs in the compression stroke portion of the detection result of the cylinder pressure sensor, the cylinder representative output value CB) becomes an abnormal value.

The ignition timing of the cylinder for which ignition timing control is performed based on this may become inappropriate.

In addition, in such an internal combustion engine control device, the correspondence between a specific cylinder and a cylinder pressure sensor is uniquely fixed, and ignition timing control for that specific cylinder is performed based on the detection of one cylinder pressure sensor. It is designed to be based only on output.

Therefore, when the cylinder pressure sensor malfunctions or the integrator malfunctions, or when abnormal vibration occurs in the cylinder pressure sensor detection result f) uA stroke, the typical knock output value (K) becomes an abnormal value. , the ignition timing of the cylinder on which ignition timing control is performed based on the ignition timing may become inappropriate.

For example, if the ignition timing is retarded than the normal ignition timing, the generated torque may decrease, fuel efficiency may decrease, exhaust temperature may rise excessively, and if the ignition timing is advanced from the normal ignition timing, knocking may occur. arise. In particular, heavy knock caused by advancing the ignition timing too much can lead to engine destruction in the worst case scenario.

[Means for solving problems]

Therefore, in the internal combustion engine control device according to the present invention, the first
As shown in the figure, there is a combustion pressure vibration means A that detects the combustion pressure vibration of one engine, and a representative output that detects the representative output value of the cylinder and the representative output value of knock based on the detection results of the combustion pressure vibration detection means A. a detection means B; and a first determination means C that determines whether or not an abnormality has occurred in the detection result of the representative output value of the cylinder based on the detection result of the representative output detection means B.

A second determining means for determining whether or not an abnormality has occurred in the detection of the representative output value of knocking based on the detection result of the representative output detecting means B; and the first determining means C; Also provided is ignition timing control means E for controlling the ignition timing based on the respective determination results of the second determination means.

[For production]

When an abnormality occurs in the detection of the representative output value of a cylinder, ignition timing control is performed only based on the representative output value of knock, and when an abnormality occurs in the detection of the representative output value of knock, the detection of the representative output value of knock is normal. It becomes possible to control the ignition timing to be the same as that of the cylinder or group of cylinders.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a block diagram showing the configuration of a control device for a four-cylinder internal combustion engine embodying the present invention.

The cylinder pressure sensor 1A of the first cylinder is a piezoelectric conversion type pressure sensor, and is installed as a washer for the spark plug 22A installed in the cylinder head 21A as shown in FIGS. A charge signal Sl+ is output according to the cylinder pressure (cylinder pressure).

Note that the cylinder pressure sensors 1B to 1D for the second to fourth cylinders are also installed in the same way as the cylinder pressure sensor 1A, and
Charge signals SI2 to S corresponding to the respective in-cylinder pressures of the cylinders to the fourth cylinder
Outputs 14.

The charge amplifier 2Δ converts the charge signal S11 from the first cylinder in-cylinder pressure sensor 1A into a voltage signal, and then amplifies it.
It is output as a detection signal S21.

The same applies to charge amplifiers 2B to 2D.

Similarly to the charge amplifier 2A, each cylinder pressure sensor 1B to 1
The charge signals SI2 to S14 from D are converted into voltage signals, amplified, and output as detection signals S22 to S24.

In other words, these cylinder pressure sensors 1A to 1D and charge amplifiers 2A to 2D constitute the combustion pressure vibration detection means A in FIG. 1.

In addition, the crank angle sensor 3 detects the position before the compression top dead center of each cylinder (
BTDC) At the same time as outputting the reference signal S2 at 70 degrees, the position signal S3 is output every 1 or 2 degrees of the crank angle.

Note that, of the reference signal S2, the reference signal corresponding to the first cylinder has a wider pulse width than the reference signals corresponding to the other cylinders.

The idle switch 4 detects whether the engine is in an idle state and outputs an idle state detection signal SI.

On the other hand, the control unit 5 is a circuit that also serves as the representative output means B, the first determination means C2, the second determination means, and the ignition timing control means E in FIG.
)6. It consists of a signal processing circuit 7, a main control circuit 8, etc.

The multiplexer 6 selects the detection signals S21 to S24 inputted from the charge amplifiers 2A to 2D in accordance with a selection signal from the main control circuit 8, and outputs the selected detection signals as a detection signal S2n.

The signal processing circuit 7 receives the detection signal S from the multiplexer 6.
2n is subjected to predetermined signal processing to convert it into a correlation value that correlates with combustion pressure vibration energy during non-knocking, a correlation value that correlates with combustion pressure vibration energy during knocking, etc.

This signal processing circuit 7, as shown in FIG.
The detection signal S2n from the multiplexer 6, which is one of the detection signals 321 to S24 from
17KHz) signal components are extracted.

Then, the detection signal (extraction signal) S4 output from the charge amplifier 7A is amplified by the amplifier circuit 7B, and the amplified detection signal S5 is half-wave rectified by the rectifier circuit 7C.

Thereafter, the half-wave rectified detection signal S6 output from the rectifier circuit 7C is integrated by the integrator 7D whose integral operation is controlled by the set/reset signal SSR from the main control circuit 8, and converted into combustion pressure vibration energy. It is output as an integral signal S7 indicating an integral value as a correlated correlation value.

Returning to FIG. 2, the main control circuit 8 is a CPU IQ.

It is composed of a microcomputer such as 11013 with built-in ROMI 1, RAMI 2, A/D converter, etc.

The main control circuit 8 receives the reference signal S2 and position signal S3 from the crank angle sensor 3, the idle state detection signal S from the idle switch 4, the integral signal 87 from the signal processing circuit 7, and the like.

Then, based on the reference signal S2 and position signal S3 from the crank angle sensor 3, a set/reset signal SSR is output to the integrator 7D of the signal processing circuit 7 to control its integration operation.

In addition, here, the main control circuit 8 is 40 degrees before compression top dead center (
Start the integration operation of integrator 7D at BTDC40°),
The integral operation is stopped at compression top dead center (TDC),
The integral operation is started again at 5 degrees after compression top dead center (ATDC), and is stopped at 45 degrees ATDC.

The main control circuit 8 also performs detection abnormality determination of the representative output value based on various input signals such as an intake air amount signal (not shown).
Determination regarding knocking 2 Determination of the amount of correction of ignition timing 1 Processing related to ignition timing control such as determination of ignition timing.

Then, the power transistor 16 of the ignition device 15 is controlled on/off based on the determined ignition timing to control the ignition timing.

The ignition timing control (on/off control of the power transistor 16) is controlled by an advance value (ADV) register (not shown) provided inside the l1013, and a dwell angle (DWELL) register (not shown).
) The value corresponding to the determined ignition timing (advance value,
The dwell angle) is set, and the values of these registers are compared with the value of the counter that counts the position signal S3, and when they match, the power transistor 16 is turned on or off.

In addition, in the ignition device 15, the power transistor 16 is controlled on and off, so that the primary current of the ignition coil 18, which is supplied with power from the battery 17, is interrupted and a high voltage is generated on its secondary side. A high voltage is selectively distributed and applied to the spark plugs 20A to 20D of the first to fourth cylinders by a distributor IS to generate spark discharge and ignite at °C.

Note that this main control circuit 8 also performs control other than control related to ignition timing, but a detailed explanation thereof will be omitted.

Next, the operation of this embodiment configured as described above will be explained with reference to FIG. 5 and subsequent figures.

First, the knocking detection principle in this embodiment will be explained.

It is generally believed that the knock level is determined by human auditory sense based on the relative intensity difference between the sound pressure level due to constantly occurring background noise and the sound pressure level due to knocking vibration.

Therefore, by directly comparing the vibration energy of the cylinder pressure during non-knocking (combustion pressure vibration energy) with the vibration energy of the cylinder pressure during knocking, it is possible to detect the knocking level that closely matches human sensory evaluation. .

By the way, it can be said from experience that knocking does not occur before top dead center, so the cylinder pressure vibration before top dead center (
The integral value obtained by integrating the detected value (combustion pressure vibration) (for 11 flows) is the vibration energy of the cylinder pressure in the expansion stroke after top dead center in the non-knocking state, regardless of whether knocking occurs after top dead center. It can be said that this is the predicted value.

Therefore, the (rectified) integral value of cylinder pressure vibration within a specified crank angle range before top dead center, and the cylinder pressure within a specified crank angle range after top dead center or within a specified range including the range before top dead center. By comparing the (rectified) integral value of the vibration, the vibration energy of the cylinder pressure during non-knocking is directly compared with the vibration energy of the cylinder pressure during the combustion stroke.

In this case, the integration interval must be selected so as not to be affected by the vibration of the spark plug caused by the vibration of the seating and unseating of the intake and exhaust valves. ATDC5'~ATD
C45@ is selected.

Next, the principle of detecting knocking using only the representative knock output value, that is, the rectified integral value of cylinder pressure vibration during the expansion stroke, will be explained.

As mentioned above, the (rectification) integral value of cylinder pressure vibration before top dead center is a predicted value of the (rectification) integral value of cylinder pressure vibration in the expansion stroke after top dead center in the non-knocking state.

Here, as an alternative to the (rectification) integral value before top dead center, consider the average value of the (rectification) integral value of cylinder pressure vibration in the expansion stroke after top dead center, that is, the average value of the representative knock output value. .

When the frequency of occurrence of knock is low, the average value of the representative knock output values corresponds to the (1!flow) integral value of the cylinder pressure vibration during the expansion stroke after top dead center during the non-knocking time.

As long as the ignition timing is controlled normally, the frequency of occurrence of knocking will not increase, and the average value of the representative output values of knocking substantially corresponds to the representative output value during non-knocking.

Therefore, by comparing the average value of the (rectified) integral value of cylinder pressure vibration in the expansion stroke after top dead center with the (rectified) integral value of cylinder pressure vibration in the expansion stroke after top dead center, it is possible to By directly comparing the cylinder pressure vibration energy during the combustion stroke with the cylinder pressure vibration energy during the combustion stroke, it is possible to detect a knocking level that closely matches human sensory evaluation.

In addition, when strong knocking is detected, the (rectification) integral of the cylinder pressure vibration in the expansion stroke after top dead center is calculated from the average value of the C1Ii flow) integral value of the cylinder pressure vibration in the expansion stroke after top dead center. By excluding the value, the knocking level can be detected more accurately.

Next, the control of the integration operation of the integrator 7D of the signal processing circuit 7 by the main control circuit 8 for performing such processing will be explained with reference to FIG.

First, in a four-cylinder internal combustion engine, the first cylinder #1 to the fourth cylinder
The ignition of cylinder #4 is controlled in the order of #1→#3→#4→#2→#1.

At this time, the crank angle sensor 3 outputs the reference signal S2 at 70 degrees before the top dead center (TDC) of each cylinder as shown in FIG. The position signal S3 is output every 1° (or 2°) of crank angle. Note that, as mentioned above, the pulse width of the reference signal S2 for the first cylinder is different from the reference signal S2 for the other cylinders.
The pulse width is wider than .

On the other hand, cylinder pressure sensors 1A to 1D and charge amplifier 2A
~When 2D is normal, from charge amplifier 2A,
A detection signal SΣ as shown in FIG.
~S24 is output, so from the multiplexer 6,
A detection signal S2n as shown in FIG. 4(d) is output.

Thereby, the detection signal S from this multiplexer 6
When only a signal of a predetermined frequency is extracted from 2n by the bandpass filter 7A of the signal processing circuit 7 and amplified by the amplifier circuit 7B, a detection signal S5 as shown in FIG. By rectifying this signal in a rectifier circuit 7C, a detection signal S6 as shown in FIG.

Therefore, the main control circuit 8 activates an internal counter and starts counting the position signal S3 from the time when the reference signal S2 from the crank angle sensor 6 is input.

Then, as shown in FIG. Then, set/reset signal SSR is set to H'' and integrator 7D
The integration operation is started, and at time t2 when TDC is reached, the set/reset signal SSR is set to L" to stop the integration operation.

Thereafter, the integrator 7D similarly starts the integration operation at time t3 when ATDC 5°, and stops the integration operation at time t4 when ATDC 45'.

Thereby, the integral signal S7 output from the integrator 7D
between time points t1 and t4, for example, as shown in FIG. The integral operation between t3 and t4 provides a correlation value (integral value) that correlates with the vibration energy at the time of knocking.

Since the main control circuit 8 controls the integration operation of the integrator 7D at the same timing for the second to fourth cylinders, the integral signal S7 outputted from the integrator 7D as a whole is shown in FIG. It becomes as shown in .

Therefore, in a process not shown, the main control circuit 8 A/D converts the integral signal S7 at each TDC, and converts the integrated signal S7 at each TDC into a
The /D conversion value is stored at a predetermined address in the RAM 12 as an amount B correlated to the vibration energy during non-knocking, which is the representative output value of the cylinder.

In addition, the integral signal S7 at each ATDC 45° is A/D
This A/D conversion value is converted into an amount correlated to the vibration energy at the time of knocking, which is the representative output value of knocking, and is stored in the RAM.
12 predetermined addresses.

Regarding knocking control, the ratio between this amount B and the amount (K/B) or the ratio between the average value of the amount and the amount (K/B)
K) is calculated and used.

Next, a description will be given of the principle of determining an abnormality in the detection of an amount that is a representative knock output value (K).

Generally, the amount corresponding to the vibration energy of the cylinder pressure during the combustion stroke has a minimum value when the internal combustion engine is running at idle;
Under no other operating conditions will the amount be less than the amount at idle.

FIG. 6 shows the results of measuring the quantity K for each operating condition of a four-cylinder internal combustion engine under conditions where knock does not occur by the present applicant.According to various experiments, the relationship shown in the figure is can be considered to hold true for most engines.

Therefore, the value of the amount during idling operation, that is, the minimum value of the amount, is stored in advance at a predetermined address in the RAM 12 as the minimum knocking representative value KM, and the amount under operating conditions other than idling is stored in advance as the minimum knock representative value KM. By comparing KMIN with the knock minimum representative value KMIN, it can be determined that an abnormality has occurred in the detection of the knock representative output value (K) for that cylinder when K<KMIN.

Here, to explain how to obtain the minimum representative knock value KM-N, the amount K during idling may be used as the minimum representative knock value KM-N, or a more stable minimum representative knock value KM-N may be used. In order to obtain the moving average value of the amount during idle operation, KMIN=(1-α)KMIN+αK However,
The value calculated by (iL calculation) of (0 × α<1) is the knock minimum representative value KMI
It may be set to N.

Furthermore, instead of the quantity that is the vibration energy correlation value during knocking, the quantity B that is the representative output value of the cylinder described above as the vibration energy correlation value during non-knocking can also be used.

That is, the value of quantity B during idling operation, that is, the minimum value of quantity B, is set as the cylinder minimum representative value BMIN.

By storing the amount B in advance at a predetermined address in the RAM 12 and comparing the cylinder minimum representative value BMIN under operating conditions other than idling, when B (BM Typical cylinder output value (B
) can be determined to have detected an abnormality.

Also, to explain how to obtain the cylinder minimum representative value BMIN, fiB during idling operation may be used as the cylinder minimum representative value BMIN, and in order to obtain a more stable cylinder minimum representative value BMIN, The moving average value of quantity B during idling operation is BMIN=(1-α')BMIN+α
'B However, the value calculated by calculating (0 x α' x 1) may be used as the cylinder minimum representative value BMIN.

Next, details of abnormality determination and ignition timing control executed by the main control circuit 8 will be explained with reference to FIG. 7 and subsequent figures.

Referring to FIG. 7, cylinder discrimination processing is performed in 5TEP 1. This is done by starting an internal counter to count the position signal S3 from the crank angle sensor 3 when the reference signal S2 from the crank angle sensor 3 is input (when it rises), and when the reference signal S2 falls. It is determined whether or not it is the first cylinder based on the count value when the cylinder is turned on, and other cylinders are determined based on the result of this determination.

In other words, as mentioned above, the pulse width of the reference signal S2 outputted at 70° before the top dead center of the first cylinder is wider than the pulse width of the reference signal S2 outputted at 70° before the top dead center of the other cylinders. wide. For example, the pulse width of the reference signal S2 for the first cylinder is about 14 degrees, while the pulse width of the reference signal S2 for the second to fourth cylinders is 4'' to 5''.

Therefore, by measuring the pulse width of the input reference signal S2, for example, if the count value is 10 degrees or more, it can be determined that the cylinder is the first cylinder. 4 cylinders.

Since the order is the second cylinder, each cylinder can be identified.

Then, drive the multiplexer 6 with 5TEP2, and
Detection signals S21 to S24 from charge amplifiers 2A to 2D corresponding to the cylinders according to the cylinder discrimination results in TEP 1
Select one of them and output it as the detection signal S2n.

After that, as described above in 5TEP 3, the signal processing circuit 7
Set the integration timing of integrator 7D.

Between BTDC40' and TD, C and ATDC,5' to 4
5", the integrator 7D performs an integration operation.

Then, in 5TEP 4 to 10, the cylinder is discriminated in 5TEP 1, and the ignition timing control system is judged to be abnormal according to the result, and the ignition timing correction amount is determined.
Performs cylinder correction amount determination processing.

FIG. 8 is a flowchart showing in detail the i-th cylinder correction amount determination process in FIG.

First, the meanings of the abbreviations used in the figure (excluding those already explained) will be explained.

FLG: A 4-bit abnormal cylinder flag stored in the RAM 12 in advance, where bit BO is the first cylinder.

Bit b is the second cylinder, and bit b2 is the third cylinder.

Bit b3 indicates whether the fourth cylinder is normal or abnormal.

dci: Ignition timing correction amount, the first cylinder is dc,...
The second cylinder is dc2. 3rd cylinder is dc3° 4th cylinder is dc
Represented by 4.

Note that if dci is positive, it represents an advance angle correction amount, and if it is negative, it represents a retard angle correction amount. In other words, it is assumed that the larger the correction amount is, the more the ignition timing advances.

Min (dci): The most retarded ignition timing correction amount among the ignition timing correction amounts for other cylinders other than the relevant cylinder (for example, if it is the 1st cylinder, the other 2nd to 4th cylinders) means.

KMINl: Quantity K during idling operation, that is, the minimum knocking representative value, and the first cylinder is KMINl.

The second cylinder is KMIN2. The third cylinder is expressed as KMIN3°, and the fourth cylinder is expressed as KMIN4.

α: Means the correction coefficient of the minimum knock representative value KM engineering N, 0
α<1.

BpAINi: Quantity B during idling operation, that is, the cylinder minimum representative value, the first cylinder is B M I N 1 + the second
The cylinder is BMIN2. The third cylinder is represented by BMIN3°, and the fourth cylinder is represented by BMI, N4.

α′ means the correction coefficient of the two-cylinder minimum representative value BM engineering N,
This value is 0<α′<1.

Next, the correction amount determination process for the i-th cylinder (i=1 to 4) will be explained with reference to FIG.

In this case, the detection signal of the i-th cylinder among the detection signals 321 to S24 from the charge amplifiers 2A to 2D is selected from the multiplexer 6 through the process of 5TEP 2 described above, and is sent to the signal processing circuit as the detection signal S2n. has been entered.

Therefore, the rectified integral signal S7 of the detection signal S2n in a predetermined angle range is A/D converted at TDC at 5TEPII to obtain the quantity B, and A/D converted at ATDC 45° to obtain the quantity K.

Then, at 5TEP 12, the state of the idle switch 4 is checked to determine whether or not it is in the idle state.

At this time, if the engine is in the idle state, in 5TEP 13, the minimum knock representative value KMINi corresponding to the JIK of the i-th cylinder at idle is rewritten.

In other words, the moving average value of the idle amount is (1-α
)・KMINi+α, and the calculated moving average value is stored at a predetermined address in the RAM 12 as a new minimum knock representative value KM-Ni.

Then, at 5TEP14, the cylinder minimum representative value BMINi corresponding to the idle amount B of the i-th cylinder is rewritten.

In other words, the moving average value of the amount B during idling is expressed as (1-α
')・BMINi+α'B is calculated, and the calculated moving average value is stored at a predetermined address in the RAM 12 as a new cylinder minimum representative value BMINi.

Then, at 5TEP15, the ignition timing correction amount dc of the i-th cylinder
i is set to rOJ (dci←0), that is, in this embodiment, control is performed using the basic ignition timing during idle.

On the other hand, if it is not idle at 5TEP12,
5TEP16 compares iK with the minimum representative knock value KM engineering Ni corresponding to the amount K of the i-th cylinder at idle, and determines that K≧
Determine whether it is KMINi or not.

At this time, if K≧KM-Ni, that is, if the detection of the knock representative output value (K) of the i-th cylinder is normal, then 5
At TEP 17, the bit bi of the flag FLG indicating whether the i-th cylinder is normal or abnormal is set to "0", and this result is stored at a predetermined address in the RAM 12.

That is, if it is the first cylinder, the read flag FLG
The least significant bit bo is set to "0" by taking the AND (FLG·1110) of the value of (bits b3 to bo) and rl 110J.

If it is the second cylinder, the read flag FLG (bit b
3~bo) and rl 101J (FLG・
1101), the least significant bit b1 is set to ``0''.
”.

If it is the third cylinder, the read flag FLG (bit b
3~bo) and rl O11J (FLG・
1011), the least significant bit b2 is set to ``0''.
”.

If it is the fourth cylinder, the read flag FLG (bit b3
~bo) and ro 111J (FLG・0
111), the least significant bit b3 is set to “OJ
Make it.

After that, at 5TEP18, JiB and the cylinder minimum representative value IIMINi corresponding to the amount B of the i-th cylinder at idle.

It is determined whether B≧B M I N i or not.

At this time, if B≧B M I N i, that is, if the detection of the representative output value (B) of the i-th cylinder is normal, the amount B that is the representative output value (B) of the cylinder is detected at 5TEP19.
The ratio of (K/B) to the amount that is the representative knock output value (K)
), and the ignition timing correction amount dci of the i-th cylinder is calculated according to the calculation result.

Furthermore, if B≧BMINi, that is, if the detection of the representative output value (B) of the i-th cylinder is abnormal, 5TE
In P20, calculate the ratio (K/K) between the amount that is the representative knock output value (K) and the average value of this amount, and adjust the ignition timing correction amount dci for the i-th cylinder according to this calculation result. Perform the calculation process.

In other words, when the detection of the representative output value (B) of the i-th cylinder becomes abnormal, control using the representative value (B) of that cylinder is stopped and only the representative output value of knock (K) is detected. Switch to the ignition timing control used.

On the other hand, if KMINi is not ≧KMINi at 5TEP16, that is, when an abnormality occurs in the detection of the knock representative output value (K) of the i-th cylinder, the flag F is set at 5TEP21.
The bit bi of LG is set to "1" and stored at a predetermined address in the RAM 12.

In other words, if it is the first cylinder, the logical OR (FLG
+OO01) bit b of flag FLG. Set to "1".

If it is the second cylinder, the read flag FLG (bit b
3~bo) and ro O10J (FLG+0
bit b1 of flag FLG by taking bit 010).
Set to "1".

If it is the third cylinder, the read flag FLG (bit b
3~bo) and ro 100J (FLG+01
00), bit b2 of flag FLG is set to "1".

If it is the fourth cylinder, the read flag FLG (bit b
3-bo) and rlooOJ (FLG+100
0), bit b3 of flag FLG becomes “
1”.

After that, flag FLG is rl 111J at 5TEP22
It is determined whether or not the detection of the representative knock output value (K) for all cylinders is abnormal.

At this time, if the flag FLG is not rl 111J,
In other words, if the detection of the knock representative output value (K) of one or more cylinders is normal, the i-th ignition timing correction amount Min (dci) which is the most retarded among the normal cylinders is determined in 5TEP23.
The cylinder ignition timing correction amount dci is determined (dci←Mi
n (da t)).

In other words, when an abnormality occurs in the detection of the representative knock output value (K), the ignition timing of that cylinder is changed to the one in which knocking is most likely to occur among the other cylinders whose representative knock output value (K) is normally detected. Adjust to the ignition timing of the cylinder, that is, the cylinder with the longest ignition delay.

On the other hand, at 5TEP 22, the flag FLG becomes “1”.
111'', that is, the detection of the knock representative output value (K) of all cylinders is abnormal.

5TEP24 sets the correction amount dci of the ignition timing of the i-th cylinder as "
0” (dci←0).

That is, at this time, control is performed to the basic ignition timing, which is set with sufficient margin for the knock limit.

Next, details of the ignition timing correction amount calculation process (STEP L9) using the ratio (K/B) in FIG. 8 will be explained with reference to FIG.

First, the meaning of each abbreviation in the figure (excluding those already explained) will be explained.

SL: A reference value for determining the presence or absence of knocking.

KFLG: A flag used to determine the presence or absence of knocking.

BCNT: Value indicating the number of ignitions since the knock KFLG was reset (hereinafter referred to as "count value BCNTJ") KCNT: Value indicating the number of ignitions since the time the knock KFLG was set (hereinafter referred to as "count value KCNTJ") Note that KFLG, KCNT, and BCNT are individually provided for each cylinder correction amount determination process.

First, in 5TEP31, calculate the ratio (K/B value) between JiB, which is the vibration energy correlation value during non-knocking, and the amount, which is the vibration energy correlation value during knocking, and calculate the amount K based on the amount B. To normalize the /B calculation process.

Then, in 5TEP32, the K/B value calculated by the above-described process is compared with the reference value SL to determine whether the K/B value>SL, thereby determining whether knocking has occurred.

At this time, if the K/B value>SL, that is, if knocking has occurred, the process moves to 5TEP43, which will be described later.

On the other hand, if the K/B value is not > SL, that is, /B value ≦ SL, and knocking has not occurred, 5TEP33 and 5TEP44, which will be described later, set the value when knocking occurs ("1"). ) Flag KFLG
It is determined whether or not is "0".

At this time, if the flag KFLG is rOJ, that is, if knocking has not occurred, 5TIEP34-3
When the state of /B value≦SL continues for 20 cycles or more after knocking occurs in step 7, the ignition timing is advanced by one degree.

That is, after the count value BCNT is incremented (+1) L at 5TEP34, it is determined whether the count value BCNT exceeds [20''(BCNT>20) at 5TEP35.

At this time, if BCNT>20, the process is terminated, and if BCNT>20, the ignition timing correction amount dci is incremented (+1) at 5TEP36 to advance the ignition timing by 1 degree, and then 5TEP37 clears the count value BCNT (BCNT=0) and ends the process.

On the other hand, if the flag KFLG is not "0", that is, if knocking has occurred in the past, 5TEP3
When the state of /B value≦SL continues for 20 cycles or more from the time when /B value>SL in 8 to 42,
Perform processing to prevent knocking.

That is, after the count value KCNT is incremented (+1) at 5TEP38, it is determined whether the count value KCNT exceeds "20"(KCNT>20.) at 5TEP39.

At this time, if KCNT>20, the process ends, and if KCNT>20.

After resetting the flag KFLG with 5TEP40.

Clear the count value KCNT at 5TEP41 (KCNT
=O)L, 5TEP42 clears the count value BCNT and ends the process.

On the other hand, when /B value>SL at 5TEP32, that is, when a knock occurs.

5TEP43 checks whether the flag KFLG is [0] to determine whether knocking has occurred for the first time.

At this time, if the flag KFLG is rOJ, that is, if it is the first knocking, the knock KF is set at 5TEP44.
After setting LG (KFLG=1).

5TEP45 clears the count value KCNT and ends the process.゛On the other hand, if the flag KFLG is not "0", that is, if knocking occurs for the second time or later, 5TE
P46, the number of past ignitions is within 10 (KCNT≦10)
), i.e. within 10 cycles /B value > SL
Determine whether it has become.

At this time, if KCNT≦10, the above-mentioned 5TE
Execute P45 to end the process, and if KCNT≦10, decrement (-1) the ignition timing correction amount dci in 5TEP47 to retard the ignition timing by 1 degree, and then execute 5TEP45 described above. and end the process.

In this manner, when knocking occurs, the frequency of knocking is determined, and the amount of correction of the ignition timing is determined based on the frequency determination result.

In addition, the correction amount dc in each of the above 5TEPs 36 and 47
Regarding i, it is determined whether the correction amount dci after correction does not exceed a predetermined value.

By limiting the value of the correction amount dci, it is also possible to prevent one ignition timing from advancing or retarding by more than a predetermined value.

Also, the amount of retardation that is decremented by 5TEP47 is:

The angle is not limited to 1 degree, such as 1/2 degree or 174 degrees, but can also be set to a value depending on the magnitude of the /B value, that is, the intensity or degree of the knock.

Next, the ignition timing correction amount calculation process (STEP 20 ) using the ratio (K/K) in FIG. 8 will be described with reference to FIG. 10.

Note that this process is almost the same as the ignition timing correction amount calculation process using the ratio (K/B) shown in Figure S.
Abbreviations SL, KFLG, BCNT, K with the same meaning as in the figure
Add "'" to CNT, SL', KFLG
', BCNT', KCNT', and 5T in Figure 9.
For EP31-47, 5TEP31'-47' is used.

First, the ratio of the average value π to iK (K/π value), which is the vibration energy correlation value during knocking mentioned in 5TEP31'
is calculated, and the /π calculation process is performed to normalize the quantity K based on the average value K of the quantity. Note that this 5TEP 31' also calculates the amount at the same time.

To calculate the average value of this quantity, for example, calculate the moving average value of the quantity by calculating ■=(1-β)K+β exactly as 0<β<1), and then calculate this value as the average value. Let it be R.

Then, the /π value calculated in 5TEP32' is set to the reference value S
It is determined whether knocking has occurred by comparing it with /L' and determining whether the value of /L>SL.

Since the subsequent process is the same as the ignition timing correction amount calculation process using the ratio (K/B) explained in FIG. 1S, the explanation will be omitted.

Next, the ignition timing control process will be explained with reference to FIG. 11.

This process is entered and executed when, for example, the reference signal S2 from the crank angle sensor 3 is input.

First, in 5TEP61, the basic ignition timing is determined according to the intake air amount, engine speed, etc. Please note that this is a ROM
This is done by looking up a table of characteristic values stored in II, for example, as shown in FIG.

Then, in 5TEP62 to 68, the determined basic ignition timing and the correction amount dci determined by the process described above are
Based on, calculate (70(D+dc i)),
BTDC (D+d c'i) is converted into an angle from the input timing of the reference signal S2, and in 5TEP69, this calculation result is set in the advance angle value (ADV) register mentioned above in step 1013.

In this way, in this internal combustion engine control device, the representative output value of the cylinder and the representative output value of knock detected based on the detection result of combustion pressure vibration, and whether or not there is an abnormality in the detection of each representative output value. The ignition timing is controlled based on each determination result.

Therefore, when the detection of the cylinder's representative output value (B) becomes abnormal, ignition timing control using the ratio (K/B) between the cylinder's representative output value CB) and the knock representative output value (K) Instead, ignition timing control is performed using only the knock representative output value (K), and when the detection of the knock representative output value (K) becomes abnormal, the knock representative output value (K) for that cylinder is
Instead of the ignition timing control using K), the ignition timing of another cylinder can be controlled using the ignition timing control using the representative knock output value (K).

As a result, even if an abnormality occurs in the detection of the representative output value of a cylinder or the detection of the representative output value of knock for some cylinders, it is possible to reduce the generated torque, reduce fuel consumption, increase exhaust temperature, or cause knocking. This inconvenience can be avoided.

In this case, as in the above embodiment, by matching the detection of the typical knock output value to the cylinder with the latest ignition timing among the normal cylinders, the occurrence of knocking can be suppressed while the generated torque is reduced and fuel efficiency is reduced. , the increase in exhaust gas temperature, etc. can be suppressed to a minimum.

Furthermore, even when the detection of the representative output value of knock becomes abnormal for all cylinders as in the above embodiment, control is performed using the basic ignition timing, which is set on the retarded side with a margin for the knock limit. Suppresses knocking and reduces generated torque.

It is possible to suppress a decrease in fuel efficiency, a rise in exhaust gas temperature, etc.

In each of the above embodiments, the cylinder pressure sensor is provided in the spark plug, but a so-called vibration sensor may be provided in the cylinder block.

Further, in the above embodiment, an example was described in which the ignition timing is controlled for each cylinder, but the present invention can be similarly implemented in a case where a plurality of cylinders are set as one group and the ignition timing is controlled for each cylinder group.

〔Effect of the invention〕

As explained above, according to the present invention, the representative output value of the cylinder and the representative output value of knock detected based on the detection result of combustion pressure vibration, and the determination of whether or not the detection of each of these representative output values is abnormal. Since the ignition timing is controlled based on the results, when the detection of the representative output value of a cylinder becomes abnormal, only the representative output value of knock is used instead of controlling the ignition timing using the representative output value of that cylinder. If the detection of the representative knock output value becomes abnormal, the ignition timing control of other cylinders should be performed instead of the ignition timing control using the representative knock output value of that cylinder. It is now possible to perform matching control, reducing the generated torque while suppressing the occurrence of knocking due to abnormal detection of each representative output value due to malfunction of the integrator or abnormal vibration on the detection signal of in-cylinder pressure (combustion pressure vibration). , it is possible to avoid disadvantages such as a decrease in fuel efficiency and an increase in exhaust gas temperature.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a block diagram showing the configuration of a control device for an internal combustion engine implementing the present invention, and FIG. 3 is a sectional view showing an example of the cylinder pressure sensor. FIG. 4 is a block diagram showing an example of the signal processing circuit. FIG. 5 is a timing chart diagram for explaining the integral operation control process of the integrator executed by the main control circuit. FIG. 6 is a diagram showing characteristics of engine speed and intake air amount-amount for explaining the principle of detecting abnormality determination of representative output value of knock. FIG. 7 is a flowchart showing abnormality determination and ignition executed by the main control circuit. Figure S is a flow diagram showing an example of the ignition timing correction amount calculation process using the ratio (K/B) in Figure 8, and Figure 10 is the ignition timing correction using the ratio (K/K) in Figure 8. FIG. 11 is a flow diagram showing an example of the ignition control process executed by the main control circuit; FIG. 12 is the engine rotational speed for explaining the basic ignition timing calculation process in FIG. 11; - It is a diagram showing intake air flow rate-advanced angle value characteristics. 1A-ID... Cylinder pressure sensor 2A-2D... Charge amplifier 3... Crank angle sensor 4... Idle switch 5... Control unit 7... Signal processing circuit 7C... Rectifier 7D. ... Integrator 8... Main control circuit 15... Ignition device Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 11

Claims (1)

[Claims] 1. A control device for an internal combustion engine that controls ignition timing based on a detection result of combustion pressure vibration of the internal combustion engine, comprising a combustion pressure vibration detection means for detecting combustion pressure vibration of the engine, and a detection result of the combustion pressure vibration detection means. representative output detection means for detecting the representative output value of the cylinder and the representative output value of knock based on the representative output value of the cylinder; and whether an abnormality has occurred in the detection result of the representative output value of the cylinder based on the detection result of the representative output detection means. a first determination means for determining whether or not an abnormality has occurred in the detection of the representative output value of the knock based on the result of the representative output detection means; and a detection means for the representative output detection means. 1. A control device for an internal combustion engine, comprising ignition timing control means for controlling ignition timing based on the results and the determination results of the first determination means and the second determination means.