JP3050640B2 - Knock detection method for multi-cylinder engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knock detection method for a multi-cylinder engine that determines whether knock has occurred based on a detection output from a knock sensor.

[0002]

2. Description of the Related Art As is well known, knock generated by abnormal combustion of an air-fuel mixture of an engine can be detected by a knock sensor as combustion pressure vibration or mechanical vibration transmitted to a cylinder block or the like.

[0003] Regarding the signal processing from the knock sensor, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 2-272327, which was previously submitted.
In Japanese Unexamined Patent Application Publication No. 2-272328, a signal from a knock sensor is continuously analog-to-digital (A / D) converted at a high speed within a specific period of a combustion cycle.
A technique of so-called digital knock detection processing has been proposed, and this technique has made it possible to accurately determine the presence or absence of knock without accompanying a decrease in reliability due to aging of analog waveform processing.

Generally, in this digital knock detection process, a signal from a knock sensor is A / D-converted at a high speed in a predetermined sample section, and an average value of the amplitude of the knock sensor signal in the section is obtained from the A / D converted data. Ask. Since the average value in this section changes depending on the magnitude of noise and the presence or absence of knock and varies between cycles, it is usually a weighted average and multiplied by a coefficient according to operating conditions such as engine speed, and is a comparison reference level. The background level is set to a stable value.

Then, A / D conversion data having an amplitude exceeding the background level is extracted, the difference between the A / D conversion data and the background level is integrated, and the integrated value is compared with a knock determination level to determine whether knock has occurred. So that
The knock determination level is set so that the magnitude of the knock is constant when confirmed by hearing or an in-cylinder pressure sensor.

[0006]

However, in a system using a plurality of knock sensors in a multi-cylinder engine, the noise in the knock sensor detection output differs in each cylinder and knock sensor, and the background noise increases. The level increases when the engine rotates at a high speed and under a high load, and the required value of the background level changes suddenly, such as during transient operation.

For this reason, the background level after the weighted averaging cannot not only keep up with the required value, but also the background level calculation value of another cylinder changes due to the knock generated in one cylinder. Furthermore, if weighted averaging is performed for each engine cycle, the responsiveness at low engine speed will be significantly degraded. Conversely, in the next cycle in which knock has occurred, the average value of the amplitude within the section will increase, so the background level The calculated value becomes larger than the required value.

[0008] Accordingly, one of the signals from the knock sensors obtained from all the cylinders or the signals from all the knock sensors is used.
With one background level and one knock determination level, it is not always possible to accurately determine whether knock has occurred for all engine operating states and all cylinders, and erroneous knock detection and knock detection failure occur. There was a fear.

The present invention has been made in view of the above circumstances, and all engines
Operating condition, the presence or absence of knocking for all the cylinders can be determined accurately, multi can improve the knock detection accuracy by preventing erroneous knock detection and knock detection failure
An object of the present invention is to provide a knock detection method for a cylinder engine.
I do.

[0010]

Means for Solving the Problems To achieve the above object,
Therefore, according to the first aspect of the present invention, a sample section is set for each cylinder.
Set the signal from the knock sensor in the sample section
From the A / D converted data to the center value.
The absolute value of the difference is integrated to calculate the integrated value of the amplitude data.
The absolute value of the difference between the A / D conversion data and the center value is
When the background level exceeds
From the absolute value of the difference between the D conversion data and the center value,
And subtract the background level from
Accumulate as knock intensity, and at the end of sample interval,
From the amplitude data integration value,
Calculate the average value of the width data, and then calculate the average
The background level for the corresponding cylinder.
The knock strength and engine operation
For comparison with the knock determination level set based on the state
In a knock detection method for a multi-cylinder engine that detects knock of a corresponding cylinder ,
Increase the value at low engine speed based on the engine speed.
Knock determination level based on basic data and engine load
To correct the basic data for the knock determination level
And the above-mentioned knock determination level
The basic data is corrected by the above correction coefficient to
Set a bell and set it in advance for a predetermined time or at predetermined intervals
Weighted average speed proportional constant multiplied by engine speed
A / D conversion used when setting the background level
The weight of the weighted average when calculating the average amplitude of the data
Set the background speed based on the engine speed.
At the end of the sample interval.
Knock determination level, weight of the weighted average, and
Read the Kg ground coefficient and determine the knock determination level and
The knock is detected by comparing the knock intensity with the knock intensity.
The amplitude in the sample interval determined from the integrated value of the amplitude data
The average value of the width data is weighted by the weight of the weighted average.
And the background coefficient is added to this weighted average.
By multiplication, the background level for the cylinder
It is characterized by setting a bell .

[0011] The invention according to claim 2 is the invention according to claim 1.
Ming, the multi-cylinder engine has multiple banks
The engine is equipped with a knock sensor for each bank.
Therefore, the knock determination level basic data and the background
Set the land coefficient for each bank and arrange for each bank
The above knock determination is performed by bank corresponding to the knock sensor
Set a constant level and set the
Using the corresponding background coefficient above,
To and sets the background level of
You.

The invention according to claim 3 is the invention according to claim 1 or
In the invention described in claim 2, in a predetermined time or at a predetermined cycle.
To the preset weighted average speed proportional constant
Multiplied by the number of rotations and used when setting the background level
Weight when calculating the average amplitude value of A / D conversion data
Set a variable that is the basic value of the average weight, and then
Weighted average rate acceleration to reduce the weight of the weighted average if in medium
In addition to correcting the above variables with the time coefficient,
If there is a risk, the above variables are further weighted by the weighted average.
Correction by the knock occurrence coefficient which increases
The coefficient is set as the weight of the weighted average .

[0013]

[0014]

[0015]

According to the first aspect of the present invention, a predetermined time or a predetermined
Each period, based on the engine speed,
Knock determination level basic data that takes a large value and engine
The above knock determination level basic data is supplemented based on the
Set a correction coefficient to correct
The judgment level basic data is corrected by the correction coefficient
Set the lock judgment level. In addition, at a predetermined time
For each fixed period, a preset weighted average speed proportional constant
Multiply engine speed to set background level
When calculating the average amplitude value of A / D conversion data used at the time
Set the weight of the weighted average of the
Set the background coefficient based on. In addition,
Set a sample section for each cylinder, and
A / D conversion of the signal from the
Amplitude data by integrating the absolute value of the difference between the converted data and the center value.
Calculate the integral value and determine the difference between the A / D conversion data and the central value.
The log value exceeds the background level for the cylinder
The absolute value of the difference between the A / D converted data and the center value
Subtract the background level for the cylinder from
Then, this subtraction value is integrated as the knock intensity. And
At the end of the sample interval, the knock determination level
Read the weight of the weighted average and the above background coefficient
And comparing the knock determination level with the knock intensity
Knock is detected, and the sample is calculated from the integrated value of the amplitude data.
The average value of the amplitude data in the data section is obtained. Soshi
The average value is calculated by the weight of the weighted average.
The weighted average is multiplied by the above background coefficient.
To calculate the background level for the corresponding cylinder.
And apply it to the calculation of the knock intensity of the corresponding cylinder.
You.

The invention according to claim 2 has a plurality of banks.
Knock sensors are provided for each bank of a multi-cylinder engine
When detecting knock, the knock determination level
Basic data and the above background coefficient for each bank
Set. And, Knocksen arranged for each bank
If you set the knock determination level for each bank corresponding to the
In both cases, the backglan corresponding to the bank to which the cylinder belongs
The background level for the corresponding cylinder is set using the coefficient .

According to a third aspect of the present invention, a background level
Calculates the average amplitude of A / D conversion data used when setting the bell
When setting the weight of the weighted average when issuing
A pre-set weighted average rotational speed for each interval or at predetermined intervals
Multiplying the engine speed by the proportional constant gives the weight of the weighted average
Set the variable that is the basic value of. And then accelerate
In the case of medium, the above variables are reduced by the weighted average rate acceleration factor.
If slight knocking occurs at this time
Further increases the above variable by the knock occurrence coefficient.
And set the correction coefficient after this correction as the weight of the weighted average.
I do.

[0018]

[0019]

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are flowcharts of a routine for setting a knock determination level, a background level weighted average rate, and a background coefficient, and FIG. 4 is a schematic diagram of an engine control system. 5 is a front view of the crank rotor and the crank angle sensor, FIG. 6 is a side view of FIG. 5, FIG. 7 is a front view of the first crank rotor and the first crank angle sensor, and FIG. 9 is a front view of a cam rotor and a cam angle sensor, FIG. 10 is a circuit configuration diagram of a control device, and FIG.
12 is a flowchart of a sample start setting routine, and FIG.
13 is a flowchart of a knock detection and background level setting routine, FIG. 14 is a flowchart of a processing routine in a main computer, FIG. 15 is an explanatory diagram showing a time series of knock detection, and FIG. 16 is an explanatory diagram showing processing of a knock signal. It is.

[Configuration of Engine Control System] In FIG.
Reference numeral 1 in the figure denotes an engine body, and in the figure, a six-cylinder horizontally opposed engine is shown. This engine body 1
The cylinder block 2 is divided into two banks (the right bank in the figure is a left bank and the left bank is a right bank) about the crankshaft 1a.
Cylinder groups of # 3 and # 5 cylinders are arranged, and # 2 and #
A group of four and six cylinders is arranged.

Each cylinder head 3 of each bank has
Each intake port 4 is formed, and each intake port 4 communicates with an intake manifold 5. The throttle chambers 6a and 6b communicate with the banks upstream of the intake manifold 5, and the throttle chambers 6a and 6b join together and communicate with the air chamber 7 on the upstream side.

An intake pipe 8 is provided upstream of the air chamber 7.
An air cleaner 9 is mounted via the air cleaner 9, and an intake air amount sensor (hot film air flow meter in the figure) 10 is interposed immediately downstream of the air cleaner 9.

The throttle chambers 6a, 6
b and the air chamber 7, throttle valves 11a and 11b are interposed respectively. A throttle opening sensor 12a and an idle switch 12b for detecting the full closing of the throttle valve are connected to one of the throttle valves 11b. Have been.

Further, each of the throttle chambers 6a, 6b
A variable intake valve 11c is interposed in a passage 6c connecting the throttle valve 11a and the throttle valve 11a, and the downstream side of the throttle valve 11b is communicated with a passage 6d. An idle speed control valve (ISCV) is provided between the passage 6d and the air chamber 7. ) 13 are interposed.

An injector 14 is disposed immediately upstream of each intake port 4 of each cylinder of the intake manifold 5, and the tip of each cylinder of each cylinder head 3 is exposed to the combustion chamber. A spark plug 15 is attached. An ignition coil 15 a is directly attached to a terminal of the ignition plug 15, and is connected to an igniter 16.

The injector 14 has a fuel tank 1
Fuel is pressure-fed from an in-tank type fuel pump 18 provided in 7 via a fuel filter 19, and the pressure is regulated by a pressure regulator 20.

A cooling water temperature sensor 21 faces a cooling water passage (not shown) formed in the cylinder block 2, and a right bank knock sensor 22a and a left bank knock sensor 22a are provided in each bank of the cylinder block 2, respectively. A bank knock sensor 22b is mounted, and each exhaust port 23 of each cylinder head 3 communicates with each exhaust pipe 24a, 24b provided for each bank.

Each of the exhaust pipes 24a and 24b has a right bank O2 sensor 25a and a left bank O2 sensor 2 respectively.
5b, catalytic converters 26a and 26b are interposed downstream of the O2 sensors 25a and 25b, respectively, and a catalytic converter 27 is interposed at the junction of the downstream of the catalytic converters 26a and 26b. ing.

On the other hand, a crank sprocket 1b is axially mounted on a crankshaft 1a of the engine body 1,
The timing belt 28 is attached to the crank sprocket 1b.
(See FIG. 6). Then, the rotation of the crankshaft 1a is transmitted to the camshaft 1c via the timing belt 28, and this camshaft 1c
Rotates 1/2 of the crankshaft 1a.

A first crank rotor 29 for detecting a crank angle and a second crank rotor 30 for discriminating a group cylinder are axially mounted on the crankshaft 1a, and the first and second crank rotors 29, 30 are provided. The first and second crank angle sensors 31 and 32 each including an electromagnetic pickup for detecting a projection which is a detection target are provided on the outer periphery of the sensor. A cam rotor 33 is axially mounted on the camshaft 1c, and a cam angle sensor 34 such as an electromagnetic pickup is provided on the outer periphery of the cam rotor 33.

As shown in FIG. 6, each of the crank rotors 29, 30 is axially mounted close to each other with a predetermined interval L2, and the crank angle sensors 31, 32 are mounted on the outer periphery of each of the crank rotors 29, 30. Is the prescribed clearance S
It is opposed to through.

The distance L2 between the crank rotors 29 and 30 is equal to the distance L1 between the crank angle sensors 31 and 32.
Therefore, the axial center of the first crank angle sensor 31 is located at the center of the thickness of the first crank rotor 29 (the crank angle detecting crank rotor). On the other hand, it is slightly offset to the crank sprocket 1b side,
The axis center of the second crank angle sensor 32 is
Is slightly offset toward the engine body 1 with respect to the center of the thickness of the crank rotor 30 (crank rotor for group cylinder discrimination).

Further, as shown in FIG. 5, the crank angle sensors 31 and 32 are arranged at a predetermined opening angle θ0 (for example, 25 °) with respect to the axis center of the crankshaft 1a. A predetermined spatial distance is maintained so that noise is not generated due to mutual influences due to a change in magnetic flux generated when the object passes through the sensors 31 and 32.

That is, each of the crank rotors 29, 3
0 can be minimized, the mutual interference of the crank angle sensors 31 and 32 can be prevented, and compactness can be achieved.
The configuration of 9, 30 can be simplified.

As shown in FIG. 7, the first crank rotor 29 for detecting the crank angle has a projection 29a formed on the outer periphery thereof, and the second crank rotor for determining the group cylinders. 30 is as shown in FIG.
A projection 30a for group cylinder discrimination is formed on the outer periphery.

The crank angle sensors 31, 3
The magnetic flux is changed when the projections 29a and 30a pass through the projections 2a and 2b. As a result, the crank angle sensors 31 and 32 output an AC voltage signal train by electromagnetic induction. Is converted to

The first crank rotor 29 for detecting the crank angle has a protrusion 29a, for example, whose starting point is 10 ° before compression top dead center (BTDC) of each cylinder is 30 °.
The waveform from the first crank angle sensor 31 which is formed at equal intervals and detects the protrusion 29a is shaped so that a crank pulse is obtained at every crank angle of 30 °.

For example, a crank pulse indicating BTDC 70 ° is a reference crank angle for calculating the engine speed NE, and also a reference crank angle for setting the ignition timing and the fuel injection timing. Further, the crank pulse indicating BTDC 10 ° becomes the crank angle of the fixed ignition timing at the time of starting.

The projections 30a of the second crank rotor 30 for group cylinder discrimination are, for example, # 1 and # 2.
One is formed at the BTDC 55 ° position of the cylinder, and # 3, #
From the BTDC 55 ° position of the four cylinders, two at every 30 °, #
5, every 30 ° from the BTDC 55 ° position of # 6 cylinder
The second protrusion for detecting the protrusion 30a.
The signal from the crank angle sensor 32 is similarly shaped to obtain a group determination pulse.

As shown in FIG. 15, zero or one group discrimination pulse is output during every 30 ° CA crank pulse, and between BTDC 100 ° and BTDC 70 °, the group discrimination pulse is output for any cylinder. There is no discrimination pulse, and the crank pulse after the pattern with the absence or presence of the group discrimination pulse always indicates BTDC 40 °, and the next crank pulse indicates BTDC 10 °.

On the other hand, as shown in FIG. 9, in order to determine the compression top dead center of the specific cylinder, the cam rotor 33 is located at, for example, 43.2 ° after the compression top dead center (ATDC) of the # 1 cylinder. , One projection 33a is formed, and individual cylinders can be determined by the cam pulse from the cam angle sensor 34 and the group determination pulse.

The first and second crank rotors 2
9, 30, or on the outer periphery of the cam rotor 33,
A slit may be provided instead of the projection. Further, the first and second crank angle sensors 31 and 32 and the cam angle sensor 34 are not limited to a magnetic sensor such as an electromagnetic pickup, but may be an optical sensor or the like. good.

[Circuit Configuration of Control Unit] On the other hand, in FIG. 10, reference numeral 40 denotes a control unit (ECU) comprising a microcomputer, which is a main computer 41 which performs ignition timing control, fuel injection control and the like.
And a sub computer 4 dedicated to knock detection processing
And 2 computers.

The constant voltage circuit 4 is provided in the ECU 40.
3, and a constant voltage is supplied from the constant voltage circuit 43 to each section. This constant voltage circuit 43
Is connected to the battery 4 via a relay contact of the ECU relay 44.
The relay coil of the ECU relay 44 is connected to the battery 45 via a key switch 46. Further, the fuel pump 18 is connected to the battery 45 via a relay contact of a fuel pump relay 47.

The main computer 41 has a main C
PU 48, ROM 49, RAM 50, timer 51, serial interface (SCI) 52, and I / O
Interfaces 53 are connected to each other via a bus line 54.

The input ports of the I / O interface 53 are connected to an intake air amount sensor 10, a throttle opening degree sensor 12a, a cooling water temperature sensor 21, a right bank O2 sensor 25a, and a left bank O2 sensor 25b. The idle switch 12b, the first and second crank angle sensors 31, 3 are connected via a converter 55a.
2. The cam angle sensor 34 is connected, and the battery 45 is connected to monitor the battery voltage.

The I / O interface 53
The igniter 16 is connected to the output port of the ISCV 13, the ISCV 13, the injector 14, and the relay coil of the fuel pump relay 47 are connected via the drive circuit 55b.

On the other hand, the sub-computer 42
U56, ROM57, RAM58, timer 59, SCI
60 and an I / O interface 61 are connected to each other via a bus line 62.

The input ports of the I / O interface 61 include first and second crank angle sensors 31, 32,
The right bank knock sensor 22a and the left bank knock sensor 22b are connected to the cam angle sensor 34.
Are the amplifier 63, the frequency filter 64, and the A /
It is connected via a D converter 65.

Each of the knock sensors 22a and 22b includes, for example, a vibrator having a natural frequency substantially equal to that of knock vibration,
This is a resonance type knock sensor composed of a piezoelectric element that detects the vibration acceleration of this vibrator and converts it into an electric signal.It detects vibration transmitted to a cylinder block and the like by a combustion pressure wave during the explosion stroke of the engine. The vibration waveform is output as a knock signal.

After the knock signal is amplified to a predetermined level by the amplifier 63, necessary frequency components are extracted by the frequency filter 64, and are converted from analog data to digital data by the A / D converter 65.

The main computer 41 and the sub-computer 42 are connected by a serial line via SCIs 52 and 60, and the output port of the I / O interface 61 of the sub-computer 42 is
The main computer 41 is connected to an input port of the I / O interface 53.

The main computer 41 calculates an ignition timing and the like based on the crank pulse, and when a predetermined ignition timing is reached, outputs an ignition signal to the corresponding cylinder.
The sub-computer 42 calculates the engine speed from the input interval of the crank pulse and, based on the engine speed and the engine load (data read from the main computer 41), knock signals from the knock sensors 22a and 22b. Is set, and the knock signal from each of the knock sensors 22a and 22b is A / D-converted at a high speed in this sample section to convert the vibration waveform into digital data faithfully, thereby determining whether or not knock has occurred.

The result of the determination as to whether or not knocking has occurred is output to the I / O interface 61 of the sub-computer 42. In the case of knocking, the sub-computer 42 transmits the signal from the main computer 41 through a serial line via the SCIs 60 and 52. The main computer 41 immediately delays the ignition timing of the corresponding cylinder based on the knock data to avoid knocking.

[Operation] First, the knock determination process in the sub-computer 42 will be described. Before determining whether knock has occurred, the sub-computer 42 determines whether or not knock has occurred in FIG.
3 are executed. This routine
Knock determination level, background level weighted average rate,
And a routine for setting a background coefficient,
It is executed every predetermined time or every predetermined period.

In step S101, the first crank angle sensor 3
The crank pulse input interval time T0 from 1 is set to a timer 59.
And the engine speed NE is calculated based on the cycle determined from the input interval time T0.

Next, the process proceeds to step S102, and based on the engine speed NE calculated in step S101, the right bank knock sensor knock determination level basic data KNLLVLB1 is referred to by referring to the right bank knock sensor knock determination level basic data table. When set, in step S103, the knock determination level basic data for left bank knock sensor KNLLVLB2 is referred to based on the engine speed NE by referring to the knock determination level basic data table for left bank knock sensor.
Set.

The basic data KNLVLB1 for the knock determination level for the right bank knock sensor and the basic data KNLVLB2 for the knock determination level for the left bank knock sensor are illustrated in steps S102 and S103 in consideration of the characteristics and mounting positions of the knock sensors 22a and 22b in advance. As described above, each of the values is obtained by an experiment or the like using the engine speed NE as a parameter and stored in the table of the ROM 57. When the engine is running at a low speed, the vibration other than the knock is large. The decision is avoided.

Incidentally, in other regions except when the engine is running at a low speed, the tendency of the basic data differs depending on the engine characteristics.
It cannot be said unconditionally.

Thereafter, when the flow advances to step S104, SCI6
The main computer 41 requests data of the basic fuel injection amount Tp as the engine load from the serial line via the lines 0 and 52, receives the data of the basic fuel injection amount Tp in step S105, and receives the basic fuel injection amount Tp in step S106. A correction coefficient KTP for correcting the basic data is set with reference to the table based on Tp.

The correction coefficient KTP is used to correct the knock determination level basic data KNLLVLB1 and KNLLVLB2 in accordance with the basic fuel injection amount Tp (engine load). The optimum value is obtained by an experiment or the like, and stored in the ROM 57 as a table, for example, set to 0.5 to 2.0 according to the basic fuel injection amount Tp.

Then, the process proceeds to a step S107, wherein the knock determination level basic data KNLLVLB for the right bank knock sensor is obtained.
1 is multiplied by the correction coefficient KTP, and a knock determination level KNLVL1 for the right bank is set (KNLVL1 ← KNLLVLB1 × KT)
P) When the data is stored at a predetermined address in the RAM 58, in step S108, the knock determination level basic data KNLLVLB2 for the left bank knock sensor is multiplied by the correction coefficient KTP.
Set knock determination level KNLVL2 for left bank (KNLV
(L2 ← KNLVLB2 × KTP) Store at a predetermined address of the RAM 58.

Next, proceeding to step S109, the engine speed NE is multiplied by a weighted average speed proportional coefficient K0 (constant value; for example, K0 = 1 / 6.25) and stored as a variable A. At step S110, the serial line Request acceleration determination result data from the main computer 41 through
In S111, the acceleration determination result data is received.

Then, in step S112, it is determined whether or not the vehicle is accelerating. If it is determined that the vehicle is not accelerating, the process proceeds to step S1.
Jump to 14, and if it is determined that the vehicle is accelerating,
Proceeding to S113, the variable A is updated to a value obtained by multiplying the weighted average rate acceleration time coefficient K1 (constant value; K1 <1.0) (A ← K1).
× A), in step S114, a knock determination flag FLAGKN
Is set to "1".

The knock determination flag FLAGKN is set and cleared in a knock detection and background level setting routine to be described later, and FLAGKN = 1.
Indicates that knock has occurred, and FLAGKN = 0 indicates that no knock has occurred, and the value is I / O as knock determination data.
Output to the output port of the interface 61.

If FLAGKN ≠ 1 in step S114, the process jumps to step S116 because there is no knock, and if FLAGKN = 1, there is a knock. The value is updated by multiplying by a coefficient K2 (constant value; K2> 1.0) (A ← K2
× A), the variable A is set to the background level weighted average ratio (weight of the weighted average) X in step S116 (X ← A).

That is, the background level weighted average ratio X is set in accordance with the engine operating state so as to be proportional to the engine speed NE and to have a small value during acceleration and a large value when knock occurs. In addition, it is possible to prevent the responsiveness of the background level from deteriorating during low rotation and acceleration, and to improve the stability of the background level when knocking occurs.

Next, in step S117, the right bank knock sensor 22a is referred to based on the engine speed NE by referring to the right bank knock sensor background coefficient table.
Bank knock sensor background coefficient KBG for
1 is set, and in step S118, the engine speed NE is set.
, The left bank knock sensor background coefficient KBG2 for the left bank knock sensor 22b is set with reference to the left bank knock sensor background coefficient table, and the routine exits.

For the right bank knock sensor background coefficient KBG1 and the left bank knock sensor background coefficient KBG2, as shown in steps S117 and S118, appropriate values that differ for each engine type are obtained in advance by experiments or the like. , ROM 57. Note that these background coefficients KBG1, KBG2
Is used when setting a background level, which will be described later.

On the other hand, every time the reference crank pulse is input, the sample start setting routine shown in FIG. 11 is started by interruption, and the sample start timing of the signal from the right bank knock sensor 22a or the left bank knock sensor 22b is set. .

The reference crank angle is, for example, BTDC
When the crank pulse of BTDC 10 ° is input to the sub-computer 42 and the interrupt process is started, the cylinder #i is determined in step S201, and a knock sensor is selected according to the determined cylinder #i. . For example, when the determined cylinder #i is # 1, # 3, # 5, the right bank knock sensor 22a is selected, and the determined cylinder #i is #
2, # 4, # 6, left bank knock sensor 22b
Select

In this cylinder discrimination, since the group discrimination pulse from the second crank angle sensor 32 does not exist in any cylinder between BTDC 100 ° and BTDC 70 °, for example, the BTDC 100
The starting point can be determined by examining the pattern of the group discrimination pulse existing up to BTDC 100 ° of the next cylinder starting from °, # 1, # 2, # 3, # 4, # 5, and # 6 cylinders. For each group, cylinder determination is performed for each group, and further, individual cylinders are determined based on the cam pulse from the cam angle sensor 34 (see FIG. 15).

Next, the process proceeds to step S202, in which the value obtained by multiplying the crank pulse input interval time T0 by the sample start angle θSTA is divided by the angle θ between crank pulses (for example, 30 °) to determine the sample start angle θSTA as a reference. Convert to sample start time TSTA from crank angle (TST
A ← T0 × θSTA / θ).

The sample start angle θSTA is determined in advance in the ROM
The optimum value for 57 is stored. That is, the knocking position is affected by the ignition timing, and this ignition timing is
Since the setting is made based on the operating conditions based on the engine speed NE and the engine load L, an appropriate sample start angle θSTA for knock detection is set to, for example, the engine speed NE,
It is obtained by an experiment in consideration of the engine load L and the like, and is stored in the ROM 57 in advance.

Thereafter, the process proceeds to step S203, where the sample start time TSTA converted in step S202 is set in the sample start timer TM1, and in step S204, the interruption by the sample start timer TM1 is permitted, and the routine exits.

When the time of the sample start timer TM1 set by the sample start setting routine reaches the sample start time TSTA, the knock detection and background level setting routine shown in FIGS. 12 and 13 is started by a timer interrupt (FIG. 15). reference).

Then, in step S301, when the values of the amplitude data integral value P1 and the knock integral value P2, which will be described later, at the time of the previous execution of the routine are cleared (P1 ← 0, P2 ← 0),
In step S302, the count value N for counting the number of times of sampling in the sample section is cleared (N ←
0) In step S303, the end time of the sample section is set by timer using the engine speed NE as a parameter.

Next, the output from the knock sensor of the relevant bank set in the above-described sample start setting routine is output to A
A / D conversion, read the full-wave rectified data,
In step S304, the converted data is used as knock determination data KN.
The data is stored as an AD at a predetermined address in the RAM 58, and is also stored as background level setting data BGAD at a predetermined address in the RAM 58 in step S305.

Then, in step S306, background level setting data BGAD and knock sensor center voltage AD
The difference (absolute value) from CNT is added to the amplitude data integral value P1 (P1 ← P1 + | BGAD−ADCNT |), and step S307 is performed.
Then, the count value N is counted up (N ← N + 1),
In step S308, the difference (absolute value) between the knock determination data KNAD and the knock sensor center voltage ADCNT is compared with the background level BGLi for the corresponding cylinder up to the previous time, and exceeds a predetermined amount with respect to the background level BGLi. Is determined.

In the above step S308, | KNAD-ADCNT
If | <BGLi, the process jumps from step S308 to step S311. If | KNAD-ADCNT | ≧ BGLi, the process advances from step S308 to step S309 to generate knock determination data KNAD and knock sensor center voltage. The value obtained by subtracting the background level BGLi from the difference (absolute value) from ADCNT is stored as a variable K (K ← |
KNAD-ADCNT | -BGLi) In step S310, the value of the variable K is added to the knock integrated value P2 (P2 ← P2 +
K).

Next, in step S311, it is determined whether or not the sample interval has ended. If the sample interval has not ended, the process returns to step S304 to continue the A / D conversion of the knock signal. When the sample section is completed, the process proceeds to step S312, where the integral value P2 is set as knock intensity data KNP (KNP ← P2).

Next, the process proceeds to step S313, where the knock determination level KNLVLj for the relevant bank is read from the RAM 58, and the knock determination is performed by comparing the knock determination level KNLVLj with the knock intensity data KNP. That is, as shown in FIG. 16, the amplitude data | KNAD obtained by full-wave rectifying the knock signal data from the knock sensor with respect to the center voltage.
-ADCNT | is integrated with data exceeding the background level BGLi, and the presence or absence of knock is determined by comparing the knock integrated value P2 with the knock determination level KNLVLj.

As a result, in the above step S313, KNP ≧
In the case of KNLVLj, it is determined that knock has occurred, and step S3
Proceeding to 14, the knock determination flag FLAGKN is set (FLAGKN ← 1), and the process proceeds to step S316, where KNP <KNL.
In the case of VLj, it is determined that no knock has occurred, and step S
At 315, the knock determination flag FLAGKN is cleared (F
LAKGN ← 0).

Thereafter, the flow advances to step S316 to calculate the average value BGAVE in the sample section by dividing the amplitude data integral value P1 by the count value N (BGAVE ← P1 / N), and in step S317, to calculate the average value BGAVE in this sample section. Average BGAVE at
Is weighted by the background level weighted average rate X set in the above-described routine, and the average value BGAVEi within the amplitude period after the weighted average of the corresponding cylinder stored at a predetermined address in the RAM 58 is updated (BGAVEi ← (BGAVE +
(X-1) × BGAVEi) / X).

Then, steps S317 to S3 are performed.
Proceeding to 18, the above average value BGAVEi within the amplitude period after the weighted average is multiplied by the background coefficient KBGj (right bank knock sensor background coefficient KBG1 or left bank knock sensor background coefficient KBG2) of the relevant bank, and Set the ground level BGLi (BG
(Li ← KBG × BGAVEi), store at a predetermined address in the RAM 58, and exit the routine.

As described above, the background level is set for each bank in accordance with the engine operating state, and the knock determination level is set for each knock sensor in accordance with the engine operating state. It is possible to accurately determine the knocking state of all engine operating states and all cylinders without occurrence of knocking, prevent knock erroneous detection and knock detection failure, and improve knock detection accuracy. You can.

On the other hand, the main computer 41 controls the ignition timing in accordance with the processing procedure shown in FIG.

That is, in step S401 of FIG. 14, the data of the knock determination flag FLAGKN is read from the output port of the I / O interface 61 of the sub-computer 42, and it is determined in step S402 whether or not knock has occurred.

If FLAGKN = 0 in step S402, that is, if knock has not occurred, the routine exits from the routine. If FLAGKN = 1, that is, knock has occurred, the process proceeds from step S402 to step S403, and A request for knock data transmission is made to the computer 42 through a serial line, and in step S404, the knock data KNP
And exit the routine.

As a result, the ignition timing of the corresponding cylinder output from the main computer 41 is delayed until the sub computer 42 outputs a determination result indicating that knock has not occurred.

The present invention is not limited to the above-described embodiment, and a knock sensor may be provided for each cylinder, and a knock determination level and a background level may be set for each knock sensor.

The knock determination process may be performed by the main computer 41, and the knock detection ECU and the ignition timing / fuel injection control ECU may be separated. Furthermore, knock sensors 22a and 22b are not limited to resonance type sensors, and detect not only mechanical vibration of an engine transmitted to a cylinder block or the like, but also combustion pressure, vibration noise, and the like as a vibration waveform. But it is good.

[0094]

Effect of the Invention] According to the calling <br/> light according to claim 1, wherein, as described, every predetermined time or a predetermined period, the engine rotational
Knock that takes a large value at low engine speed based on the speed
Based on basic data and engine load
Correction section for correcting basic data of knock determination level
And the basic data of the knock determination level.
A knock determination level is set by correcting with a correction coefficient.
At the end of the sample interval for each cylinder, the knock
Reads the constant level and determines the knock determination level and knock
Knock is detected by comparing the intensity
Knock determination level for each cylinder according to the engine operating state
Can be set accurately, and knock is determined.
Knock determination level for all engine operating conditions
Properly respond and set properly for all cylinders
Can be. The basics for setting the knock determination level
The basic data of the knock determination level, which is the value, is used as the engine speed.
Engine that has large vibration other than knock
At low speeds, the base value of the knock determination level is set to a large value.
Is fixed, so even at low engine speeds,
Eliminates the effects of external vibration to avoid erroneous knock determination
Knock can be reliably detected. Also, for a predetermined time or a predetermined period
For each period, the preset weighted average
Multiply the gin rotation speed to set the background level.
When calculating the amplitude average value of the A / D conversion data to be used,
Set the weight of the weighted average and, based on the engine speed,
And set the background coefficient. And each cylinder
At the end of each sample interval, the weight of the weighted average
Read the background coefficient and sump the
A / D conversion data of the knock sensor signal in the
Amplitude data product calculated by integrating the absolute value of the difference from the center value
Average value of amplitude data in sample interval from minute value
Ask. The average value is calculated based on the weight of the weighted average.
Weighted average, and the weighted average
Multiplies the back coefficient for the corresponding cylinder.
Set the land level and calculate the knock intensity of the corresponding cylinder
Is reflected in each cylinder according to the engine operating condition.
It is possible to set the background level accurately
Ri, bar Kkugurandore to be the base value of the knock intensity calculation
The bell is properly adjusted to all engine operating conditions,
It can be set appropriately for all cylinders. And
Make sure that each cylinder is set properly according to the engine operating conditions.
Using the knock determination level and background level
Knock detection, which affects the cylinder where knock occurred.
All engine operating conditions, all cylinders
Can accurately determine whether knock has occurred.
Knock detection and knock detection failure to prevent knock detection.
Outgoing accuracy can be significantly improved. Claim 2
According to the invention, a multi-cylinder engine having a plurality of banks is provided.
A knock sensor is provided for each bank to detect knock.
When performing the knock determination level basic data and the
The ground coefficient is set for each bank. And each
Each bank corresponds to the knock sensor arranged for each bank
Set the knock determination level to
Using the background coefficient corresponding to the bank
Since the background level for the cylinder is set,
In addition to the effects of the invention described in claim 1, a knock determination level base
This data and the background coefficient are used as characteristics for each bank.
It can be set appropriately in response. As a result,
Knocks correspond to engine operating conditions and characteristics of each bank.
Level can be set appropriately and
Set the background level for the cylinder properly.
It is possible to further improve the knock detection accuracy.
It has the effect of being able to. According to the third aspect of the invention
A / D conversion data used when setting the background level
The weight of the weighted average when calculating the
Set in advance for a predetermined period of time or for a predetermined period.
Weighted average speed proportional constant multiplied by engine speed
Then, a variable serving as a basic value of the weight of the weighted average is set.
If the vehicle is accelerating at this time, the weighted average rate
The above variables are reduced and corrected by the number
If a knock occurs, the above variables are further
The correction coefficient after this correction is weighted flat.
Claim 1 or Claim 1
In addition to the effects of the invention described in Item 2, the weight of the weighted average is
Is set in proportion to the rotational speed of the
Engines that require background-level responsiveness
At low rotation, the weight value of the weighted average becomes small,
Better responsiveness at the background level
it can. In addition, the back ground against the knock sensor output
Weight even when accelerating where
The weight of the weighted average becomes smaller due to the average rate acceleration factor.
Responsiveness at the background level
Can be. In addition, background level stability is required.
When the required knock occurs, weight is applied by the knock occurrence coefficient.
Because the value of the average weight increases, the background level
Can improve the stability of the device. Therefore,
Adapts to engine operating conditions,
Responsiveness and stability can be achieved at the same time.
Outgoing accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart of a routine for setting a knock determination level, a background level weighted average rate, and a background coefficient.

FIG. 2 is a flowchart of a routine for setting a knock determination level, a background level weighted average ratio, and a background coefficient.

FIG. 3 is a flowchart of a routine for setting a knock determination level, a background level weighted average ratio, and a background coefficient.

FIG. 4 is a schematic diagram of an engine control system.

FIG. 5 is a front view of a crank rotor and a crank angle sensor.

FIG. 6 is a side view of FIG. 5;

FIG. 7 is a front view of a first crank rotor and a first crank angle sensor.

FIG. 8 is a front view of a second crank rotor and a second crank angle sensor.

FIG. 9 is a front view of a cam rotor and a cam angle sensor.

FIG. 10 is a circuit configuration diagram of a control device.

FIG. 11 is a flowchart of a sample start setting routine.

FIG. 12 is a flowchart of a knock detection and background level setting routine.

FIG. 13 is a flowchart of a knock detection and background level setting routine.

FIG. 14 is a flowchart of a processing routine in a main computer.

FIG. 15 is an explanatory diagram showing a time series of knock detection.

FIG. 16 is an explanatory diagram showing processing of a knock signal.

[Explanation of symbols]

 22a Right bank knock sensor 22b Left bank knock sensor KNLVL1 Right bank knock determination level KNLVL2 Left bank knock determination level X Weighted average rate KBGL1 Right bank background coefficient KBGL2 Left bank background coefficient

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-141846 (JP, A) JP-A-64-32070 (JP, A) JP-A-60-256539 (JP, A) JP-A-62 255574 (JP, A) JP-A-2-301646 (JP, A) JP-A-1-216058 (JP, A) JP-A-3-145550 (JP, A) JP-A-3-145551 (JP, A) JP-A-1-109234 (JP, A) JP-A-3-121269 (JP, A) JP-A-3-85374 (JP, A) JP-A-62-249035 (JP, A) JP-A-57-32064 (JP, A) JP-A-2-272328 (JP, A) JP-A-3-56849 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 45/00 368

Claims (3)

(57) [Claims] A sample section is set for each cylinder, and a sample section is set.
A / D conversion of the signal from the knock sensor in the
And multiply the absolute value of the difference between the A / D conversion data and the center value by
To calculate the integrated value of the amplitude data.
The absolute value of the difference between the
When exceeding the land level, the above A / D conversion data
From the absolute value of the difference from the center value, the back
Subtract the ground level and use the subtracted value as the knock intensity.
At the end of the sample interval,
Average of amplitude data in the sample interval from the minute value
Value, and weighted average processing of this average value.
Setting the background level for the corresponding cylinder
Both are based on the above knock strength and engine operating condition.
By comparing with the set knock determination level,
In a knock detection method for a multi-cylinder engine that detects knock, a knock is detected based on an engine speed at predetermined time intervals or at predetermined intervals.
Knock determination level that takes a large value when the engine is running at low speed
Knock determination based on basic data and engine load
Set the correction coefficient for correcting the level basic data
And the above correction data for the knock determination level basic data
A knock determination level is set by correcting with a coefficient, and a predetermined weighted average is set every predetermined time or every predetermined cycle.
The engine speed is multiplied by the engine speed
Amplitude flat of A / D conversion data used when setting land level
Setting the weight of the weighted average when calculating the average
The background coefficient based on the engine speed.
Constant and, at the end of the sampling interval, the knock determination level,
Read the weight of the weighted average and the background coefficient
Out and compare the knock determination level with the knock intensity
To detect knock, and to determine whether
Average value of amplitude data within the sample interval
Are weighted by the weight of the weighted average.
By multiplying the weighted average by the above background coefficient
A knock detection method for a multi-cylinder engine, comprising setting a background level for a corresponding cylinder . 2. The multi-cylinder engine has a plurality of banks.
Te, engine der which is disposed a notch Kusensa to each of the banks
Therefore, the knock determination level basic data and the background
The land coefficient is set for each bank, and the bank is set according to the knock sensor provided for each bank.
Set the above knock determination level separately, and
Use the background coefficient corresponding to the bank to which the
2. The knock detection method for a multi-cylinder engine according to claim 1 , wherein a background level for the corresponding cylinder is set. 3. The method according to claim 1, wherein the predetermined time or the predetermined period is set in advance.
Multiplied by the engine speed
A / D conversion data used when setting the background level
Of the weight of the weighted average when calculating the average amplitude of the data
Set a variable that will be the actual value.
Weighted average rate to reduce weight of weighted average
Variable and the knock is occurring at this time.
In the case where
And the weighted average
2. The method according to claim 1, wherein the weight is set as
3. The knock detection method for a multi-cylinder engine according to claim 2 .