JPH06299938A - Knock control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To switch an optimum amplification factor for formation of a knock determining level so as to improve a precision of the knock determining level and to carry out more precise knock determination. CONSTITUTION:An output signal of a knock sensor 1 is amplified by plural amplifiers 22, 23 and is taken in from each of input ports AN1, AN2 of a microcomputer 24 to be A/D converted, so that existence/absence of knocking is detected. The microcomputer 24 forms a knock determination level on the basis of the signal taken in via the amplifiers 22, 23, so that this determination level is compared with the signal taken in via the amplifiers 22, 23 so as to determine a knock, and a signal of a small amplification factor is taken in from the amplifier 22 when the knock determination level is the predetermined value or more, while a signal, which is amplified by both of the amplifiers 22, 23 and has a large amplification factor, is taken in when the knock determination level is the predetermined value or less.

Description

Detailed Description of the Invention [0001] BACKGROUND OF THE INVENTION The present invention relates to an internal combustion engine (engine).
Ignition timing, air-fuel ratio, intake pressure, etc. are detected by detecting knocks that occur.
Control device for internal combustion engine for controlling various knock control factors
Regarding [0002] 2. Description of the Related Art Conventionally, knocks generated in an internal combustion engine have been detected.
And the output of this knock detection means.
The output of the amplification means and the knock detection means of the internal combustion engine
Utilizing the fact that it tends to increase according to the rotation speed
Depending on the rotation speed of the function, the amplification factor of this amplification means can be set in multiple stages.
Amplification factor changing means for changing the floor and this amplification factor changing hand
Knock by the amplified output at the amplification factor determined by the stage
The knock discriminating means for discriminating
Knock control of ignition timing, air-fuel ratio, intake pressure, etc. according to different results
A knock control factor control means for controlling the control factor
Are known (for example, JP-A-60-35238).
Gazette). [0003] [Problems to be Solved by the Invention]
In the conventional one, the output of the knock detection means is the rotation of the internal combustion engine.
Utilizing the tendency of increasing with the number, the amplification means
Switching the amplification factor of multiple stages according to the number of revolutions of the internal combustion engine
The engine speed and knock detection means
Since the magnitude of power is not unique, knock detection
The optimum amplification factor can be switched according to the output of the output means.
In particular, the knock judgment level created by the knock judgment level creating means
There is a problem that the accuracy of the bell becomes poor. Therefore, the present invention creates a knock determination level.
You can switch the amplification factor that is optimal for
Can improve the accuracy of
The purpose is to enable. [0005] Therefore, the present invention is shown in FIG.
As shown, the knock detected in the internal combustion engine is detected.
Clock detection means and an amplifier for amplifying the output of this knock detection means.
The knock determination level is determined by the width means and the output of the amplification means.
And a knock determination level creating means for creating a
Knock determination level of determination level creating means and the amplifying means
Determination means for determining knock by comparing with the output of
And the ignition timing according to the determination result of the knock determination means,
Knock control that controls knock control factors such as air-fuel ratio and intake pressure
The factor control means and the knock determination level creating means
The amplification factor of the amplification means in a plurality of stages according to the check level.
Internal Combustion Engine with Amplification Factor Changing Means for Stepwise Changing
A knock control device for a purpose is provided. [0006] As a result, the output of the knock detecting means is amplified by the amplifying means.
After being amplified by the
A knock judgment level is created, and this knock judgment level
The output of the knock detection means amplified by the amplification means is
The knock determination means determines the knock. Well
Also, it is increased by the amplification factor changing means according to the knock judgment level.
The amplification factor of the width means is changed stepwise in a plurality of steps. [0007] According to the present invention, the signal is amplified by the amplification means.
The knock determination level is created by the output of the knock detection means
Amplification of the amplification means according to this knock judgment level
Since the rate is changed stepwise in multiple steps, the knock determination level
You can switch the amplification factor that is most suitable for
You can improve the accuracy of the constant level, and
There is an excellent effect that it is possible to discriminate the black mark. [0008] Embodiments of the present invention will be described below with reference to the drawings.
It In FIG. 2, 1 is for detecting knock of the engine.
Knock sensor, which is a knock detection means for
For engine control to control ignition timing, air-fuel ratio, etc.
Electronic control unit (ECU), 3 is ignition control from ECU
An igniter that receives a signal to turn on / off the ignition coil
Engine 4 receives an air-fuel ratio control signal from the ECU 2
An injector for injecting fuel into the intake system
It Further, in the ECU 2, 21 is a knock sensor.
Only the frequency component specific to knock of the sensor output signal is passed
A filter circuit for making the signal 22 pass the signal after passing through the filter.
Amplification means for amplifying or attenuating at a constant amplification factor
An amplifier forming a part of the
Amplification for further amplification or attenuation at a fixed amplification rate
An amplifier forming a part of the means, 24 is a built-in A / D converter
Type microcomputer, 25 is various sensors and
In response to the knock detection result from the black computer 24,
Host computer for controlling fire timing, air-fuel ratio, etc.
Is. The knock sensor 1 is a piezoelectric knock sensor.
The engine block vibration caused by knocking.
Convert to qi signal. This electrical signal is a bandpass filter
The noise component is removed by passing through 21,
Frequency component peculiar to kh (eg 8KH_Z) Only amplifier
22 is input. The amplification factor of the amplifier 22 is
Output characteristics of the black sensor or an A / D converter 24 described later
It is determined in consideration of the dynamic range of a. This amplification
The amplification factor of the container 22 is G₁If so, G₁Is more than 1
It may be 1 or less. The output of the amplifier 22 is split into two, one of which
Microcomputer 24 (in this embodiment, one chip
Uses MB88413 manufactured by Fujitsu as a black computer.
Analog of the A / D converter 24a built in
Input to the input port AN1 and the other input to the amplifier 23
To be done. The amplifier 23 further outputs the output of the amplifier 22 in the previous stage.
It is for amplification, and the amplification rate is 4 times, for example.
It has become. The output of this amplifier 23 is the A / D converter 2
Input to another analog input port AN2 of 4a
Be done. By doing so, the difference is only four times.
The sensor signal that has been received is the two ports A of the A / D converter 24a.
Simultaneous input to N1 and AN2 (AN1 is amplification factor G₁,
AN2 is the amplification factor G₂= 4 x G₁). Amplification factor of amplifier 23
Can be any value, but 2,3,8, ...
Alternatively, "the power of 2" such as 1/2, 1/4, 1/8, ...
It is desirable to set to "Squared". Because the microcomputer 24 is a security
Selectively use the sensor input ports AN1 and AN2
The input gain of the knock sensor 1 is switched and controlled by
At that time, it is necessary to correct the calculated value, and the power of 2 phase
If the ratio is contrasted, the shift is easy and the execution time is fast.
This is because the calculation processing can be used. Also, a power of 2
By setting the division or multiplication function to a micro
It can be widely applied to computers. The amplifier 23 is installed in the subsequent stage of the amplifier 22.
This is because the relative signal ratio (4 times in this example)
This is to keep the degree high. That is, the output of the filter 21
Divide the force into two and put them in parallel to amplifier 22 and amplifier 23.
Output and input its output to ports AN1 and AN2.
Functionally the same. However, in this case
To maintain the accuracy of the signal ratio (for example, 4 times), the amplifier
22 gain G₁And the amplification factor G of the amplifier 23₂Both spirits
It is necessary to increase the degree (in this case, G₂/ G ₁Is relative
Because of the signal ratio). On the other hand, in the case of the embodiment, the relative
Since the signal ratio is determined only by the amplifier 23, the error can be reduced.
Wear. Now, inside the microcomputer 24,
A / D converter 24a and central processing unit (not shown)
(CPU), storage device (ROM, RAM), input / output device
Analog input port for A / D conversion with (1/0) etc.
Based on knock sensor signal values fetched from AN1 and AN2
Knock determination and knock sensor fail detection
It This knock determination result and the result of knock sensor fail
The result is output from the output port of the microcomputer 24.
The host computer for engine control at an appropriate timing.
The data is taken into the data 25 through the input port. This host computer 25 is also my
It is a black computer and is a relatively high-end computer such as 8-bit.
It is better to use a black computer. This engine
The control microcomputer 25 is shown in a known manner.
No rotation angle sensor, intake air amount sensor (air flow sensor
Ignition timing, basic injection time based on sensor signals such as
calculate. The air-fuel ratio control is based on the basic injection time.
Compensation with various sensors (eg water temperature sensor)
Add a value or change the injection time to the oxygen concentration (O₂)
Feedback control by the rich / lean signal of the sensor.
It is achieved by On the other hand, the ignition timing is based on the basic ignition timing.
According to the knock determination result of the microcomputer 24
By advancing and retarding, the
To be trolled. In addition, the microcomputer 24
Therefore, if the knock of the knock sensor 1 is detected,
Is the engine control
It is executed by the control host computer 25. Also microphone
The reset signal of the computer 24 is also used by the host computer.
25 manages. That is, the host computer 25
When the power is turned on, the host computer 25 first
Minute after initializing itself, the knock detection
It sends a reset signal to the black computer 24
Initialize. Next, the operation of this embodiment will be described. Figure 3
Knocking detection, determination, sensor failure detection of this embodiment
Microcomputer 24 for output and delay angle calculation output
The timing chart of is shown. Figure 4 shows the Microcomputer
Flow chart showing the basic program flow of data 24
It is May starting from step 220 of the start
In the routine, the built-in timer of the ignition cycle T180
Calculation (step 221), A / D conversion based on the value
Delay time to start (masking time) T1, A / D change
Conversion time (judgment time) T2, compared with A / D conversion value
The average value of the knock sensor signal to obtain the judgment level
Calculation of preliminarily experimentally determined magnification (K value) for multiplication
Step 222) and a knock sensor fail detection fan.
Ill judgment level (V_F) Calculation (step 223) is actually
Done. The output from the host computer 25
At the falling edge of the IRQ signal (211 in FIG. 3).
An interrupt is applied to the black computer 24 (see the state of FIG. 4).
211-1). In this example, on each cylinder of the engine
Before the dead center (BTDC) 10 ° CA timing
The computer 25 causes the IRQ signal to fall. Interrupt rouch
After the start of the interrupt, the interrupt process (212 in Fig. 3) is followed by masking.
Microcomputer during time T1 (213 in FIG. 3)
24 waits for A / D conversion (step 213-1 in FIG. 4) Value of time T2 (214 in FIG. 3) after the end of masking time
Only during the period of, the analog input port AN1 or AN2
The input knock sensor signal is repeatedly A / D converted,
(Step 214-1 in FIG. 4), the A / D converted value is saved.
After processing (step 214-2 in FIG. 4),
A / D conversion value V_ADAnd the judgment level V for each cylinder calculated last time_LEWhen
And compare V_LEV<V_ADCow knock pulse in case of
Up (step 214-3 in FIG. 4). Step
The A / D conversion value smoothing process in the page 214-2 is as follows.
To do so. [0020] [Equation 1] Where V_ADiIs the current A / D conversion value, V_MADi-1Last time
The result of the smoothing up to V _MADiIs the result of this annealing. Next, at step 214-4, the maximum value V
_peakPerform data replacement for calculation. Ie now
A / D converted value V_ADiIs the maximum value V up to the last time_peakThan
V if large_PeakThis time V_ADiReplace with V_ADi
Is V_PeakIf less than V_PeakValue
Save as is. This is T₂Repeat during loop
214-5), the knock determination section (T₂)
Maximum peak value V_PeakCan be obtained (see Fig. 8)
See). After the A / D conversion is completed, the A / D converter 2
The average value of 4a is calculated at the timing of 215 in FIG.
Then, the cylinder-by-cylinder judgment level for the next judgment section is calculated (see FIG. 4).
Steps 215-1 and 215-2). Where the steps
The average value of 215-1 is calculated as follows. [0023] [Equation 2] Where V_MADIs the final calculated in step 214-2
The result of the smoothing, V_{MEAN -i}Is the average value up to the previous cycle,
V_MEANIs the average value up to this time. Further, the judgment level V of step 215-2
_LEVIs calculated as follows. [0025] [Formula 3] V_LEV= K × (V_MEAN+ V_MOS) Where V_MOSCompensates for A / D conversion errors, arithmetic processing errors, etc.
It is a constant to be corrected, and is obtained in advance by experiments. More than
Knock determination level V thus obtained_LEVIs en
It changes according to the gin condition and also changes for each cylinder.
That is, V_LEVThe amount V on which the calculation of _MEANIs that cylinder
Is a quantity corresponding to the sensor output average value of
Even if the K value is constant in all cylinders, V_LEVChanges from cylinder to cylinder
It The microcomputer 24 determines for each cylinder
Level (for example, 4 cylinders with 4) in RAM area
Saved / updated. Next, the timing of 215 in FIG.
In step 215-3 of FIG.
Calculate the fail output. [0027] [Equation 4] Where V_FaiLiIs the fail output result this time, V
_FaiLi-1Is the fail output until the last time, V_peakIs already mentioned
It is the maximum peak value in the cage knock determination section. This V_Fa
iliIs V_MEANIt is calculated for each cylinder in the same manner as. Next, within the timing 215 in FIG.
The selection of the A / D conversion port in step 215-4 of FIG.
According to the flow chart shown in FIG.
Be seen. First, the microcomputer 24 is initialized
A / D conversion port has a relatively high amplification factor
Is preconfigured on the big side port of AN2
It And the engine conditions change, for example
As the number of turns increases, the sensor output increases and V_MEANIs large
Become. As a result, knock determination level [0029] [Formula 5] V_LEV= K × (V_MEAN+ V_MOS) Is a predetermined value V_MAXMore cylinders are coming out. This is shown in FIG.
A supplementary explanation will be given using (a). For example, relatively high output
Knock judgment level V for a kina cylinder (j-cylinder) _LEVIs
When the engine speed is increased, a certain value V
_MAXOver. At this time, the microcomputer 24
A / D conversion port at low cylinder timing has low amplification factor
Switch to the AN1 side (steps 261-263).
For another cylinder, knock determination level V for that cylinder
_LEVIs a predetermined value V_MAXA / D conversion port
Switch from AN2 to AN1 side (see #k cylinder in Fig. 9)
See). And the port switches from AN2 to AN1
V for the cylinder_MEAN, V_LEVSo
Then V_FaiLIs corrected by the relative signal ratio (step
264). In this example, it is 1/4. At this time, the ratio is set to a power of 2.
High-speed processing is possible with and shift calculation. Ie in this case
Is V_MEAN, V_LEV, V_FaiLShift right by 2 bits
By doing so, the value can be corrected to 1/4 at high speed. Well now
Conversely, the engine speed has decreased and V_LEVIs a predetermined value
V_MINA / D conversion port with a large amplification factor
Side (that is, switch from AN1 to AN2 side:
Steps 261, 265, 266)
V_LEV, V_MEAN, V_FaiLShift left by 2 bits (
That is, 4 times: Step 267). Therefore, for example
Under the condition that engine speed is constant, cylinder #j is on the AN1 side.
Port selection, #k cylinder is AN2 side port selection
There are also cases. Explaining this a little more, for example, four cylinders
Ignition order of # 1, # 3, # 4, # 2 cylinder
If so, the timing of knock detection for cylinder # 1
Then, take the A / D converted value from the port on the AN2 side,
At the next knock detection timing for the # 3 cylinder, the AN1 side
Because the A / D conversion value from the port is taken in
is there. By such operation, the sensor signal
The amplification factor can be switched according to the output level of the. The upper and lower switching threshold V_MAXAnd V
_MINIs higher than the relative signal ratio (4 times in this example)
If you set it with a margin, port switching characteristics
Hysteresis can be added, and hunting for switching operation
Can be prevented (see (a) of FIG. 9). Next, A
Detailed operation explanation about the / D conversion part and knock judgment output
Is performed using FIGS. Reference numeral 301 in FIG. 5 denotes 1 of the knocking detection signal.
It is equivalent to a cycle. As mentioned above, the detection signal is 8KH_ZPositive
It is a chord wave. Referring to FIG. 6, the A-D conversion program
When the ram starts (step 320), 1 chip
Comparator as a comparison function in the black computer 24
Mode is set and threshold level is set to 0 level
Th is set (step 321). And compale
Start the data (step 322), and the sine wave 301
The time TDO of the trailing edge from Th is detected (step 3
23-1), further confirm the Th level for the purpose of preventing malfunction.
(Step 323-2). After detecting the Th level,
Move on to the routine for detecting the fall from the Th level.
Step 325), a predetermined time Δ from the rise detection time TZ1
It is delayed by D (step 326), and time TS1 is reached. The rising edge detection routine (step 32
In 5), the judgments are arranged in series, and the rising is not detected.
Finally, move to step 326 for arithmetic processing
Does not fall into an infinite loop. Then time
The time to start A / D conversion from TS1 is the sine wave 301
It is set around the peak 310-1. At that time, positive
The slope near the peak of the chord wave 301 is the rising of the sine wave,
Compared to the falling slope, it is considered to be almost constant, and during delay
A / D conversion by delaying ΔD to near the peak
(Step 327) the peak value of the sine wave 301
V_PIs obtained. That is, the conversion start time T_SIThe value given by
V_SI, End time T_fiThe value V given by_fiAre both
Value V_PCompared to, the difference is extremely small, and in this example
Is because the A / D conversion uses the successive approximation A / D conversion
The obtained A / D conversion value is V_SI, V _fiThan V_PApproaching
Of. The conversion value obtained is stored in the read memory.
(Step 328) and move to the next operating step 329.
It FIG. 7 shows a pulse clock for knock intensity determination.
More details of the und part (step 214-3 of FIG. 4)
It is a flowchart. A / D converted value V_ADIs before
Cylinder-specific judgment level V determined by_LEV(Figure 4
Step 215-2) is compared (step 331), A
The / D conversion value is the cylinder-specific determination level V_LEVWas lower
Then, the operation proceeds to the next operation step 333. Cylinder judgment level
V_LEVIf it is determined to be larger, knock pulse counter
1 is added to the data (step 332). This pulse count is used during the knock determination section.
Repeat (T of step 214-5 in FIG. 4)₂Loop)
The total number of pulses in one ignition cycle is determined by and. This
The total number of pulses of becomes the amount corresponding to the knock intensity. example
For example, the total number of pulses 0-1 is no knock, 2-5 is small knock.
Ku, 6-9 are medium knocks, and more are large knocks.
The knock intensity can be classified and determined. pulse
Including the number 1 without knocking, the sharp electric noise
To prevent this from being mistaken for a knock when entering
It is a device. Of the knock intensity determined in this way
The result is obtained in step 216-1 of FIG.
From the output port of the computer 24 to the host computer 25
Sent. For example, knock strength, none, small,
If there are four types of medium and large, this is 0,1 of two signal lines.
Send to the host computer 25 in combination of
You can The host computer 25 sends this to the appropriate Thailand
Read by ming and use this information to advance or retard the ignition timing
Calculation is performed, and finally the ignition timing control signal is sent to the igniter 3.
The knock is controlled by sending. Next, the step 216-2 of FIG. 4 fails.
Details of the judgment output will be described with reference to the flowchart of FIG.
I will explain in detail. As explained above, the knock sensor
Is the maximum peak value V in the knock determination section._peak
Normalized value V_FaiLiAre using. This V_FaiLiI don't care
It is calculated for each cylinder (step 215-3), and this is
Fail judgment level V in step 216-2_FCompare with. This
This will be described with reference to FIG. 9B.
Bell V_FDepends on engine conditions (eg engine speed)
It is about to change. This fail judgment level V_FChanges from cylinder to cylinder
Although it may be changed, it is possible to use the fail judgment level common to all cylinders.
However, there is no particular problem in practical use. This fail judgment level V_F
And detected signal V_FaiLiAre compared for each ignition (step 27)
1). And this V_FaiLiIs the fail judgment level V_FYo
And the amplification factor of that cylinder is large.
Only if it fails (determined in step 272)
The counter is incremented by 1 (step 273).
And V_FaiLiIs V_FWhen an ignition cycle that exceeds
Or the cylinder with the smaller amplification factor
The fail counter is cleared to 0
(Step 274). In this way, the count value of the fail counter
Becomes a predetermined value, for example, 30 ignitions in a row
When the counter is incremented (step 275
It is judged as a sensor failure, and digital output
Send a fail signal from the port to the host computer 25
(Step 276). On the host computer 25 side
When this signal is received, the ignition timing is set to the most retarded angle, etc.
Take safety measures. The fail judgment level V_FIs the engine
Although it is a conformance constant of
Small values cannot be used. In FIG. 9B,
This lower limit is V_FminIn that case, you can switch the gain without changing the gain.
In the conventional system for detecting a failure, N₁In the above rotation range
Only fail can be detected. However, in this embodiment, this
Low rotation (N₂) Can be detected. Obey
In this embodiment, the engine speed is N
₂It is determined whether or not the above, and N₂Fail detection in the above rotation range
It is set as the execution condition. Further, as in the above-mentioned embodiment, the sensor signal is
Combustion section (knock judgment area)
The signal related to the maximum peak value in
The fail detection accuracy is further improved by
It In the above-described embodiment, the amplification factor is switched for each cylinder.
However, this may be switched to be common to all cylinders (simultaneously).
However, according to the present embodiment, the microcomputer
High-performance gain switching for each cylinder can be achieved with only this software
This embodiment is preferable because it can be achieved. Further, in the above-mentioned embodiment, the amplification factor is set in two stages.
I switched to, but it is also possible to switch to multiple stages of 3 or more
It is possible. At this time, for example, the amplification factor G
₁, G₂, G₃If so, G₁And G₂Only when
Detected (G₃Fail detection is prohibited only when
), And the fail judgment level V_FG itself₁And G
₂It is also possible to switch with. Further, in the above-mentioned embodiment, the amplifiers 22 and 2 are
3 output directly and simultaneously to the input port of A / D converter 24a.
I am inputting to AN1 and AN2.
A / D converter 24a via the analog switch 26
It is also possible to select and input to. At this time
The switching control of the switch 26 is performed by the microcomputer 24.
Can be performed by the digital port of. In addition, in the above-described embodiment, the failure detection is performed.
V as a signal_peak16 ignition smoothing value V_FaiLiUsing
But V_peakDirectly as the fail detected signal.
It can also be used. However, the smoothed value V_FaiLi
Since the accuracy of fail detection is higher when using
The example is preferable. Also, V_FaiLiCreated for each cylinder
However, it is also possible to create this for all cylinders as well.
It In this embodiment, V_peakUse the smoothed value of
And fail is detected, but V_{ME AN}Fail with
It is also possible to detect. Also V_peakMedian distribution
You can also use (cumulative 50% point) to make a fail decision
It V_peakDistribution median V_seIs V for each ignition cycle
_peakIs V_seGreater than V_se= V_se+ ΔV_se, V on the contrary
_peakIs V_seLess than V_se= V_se-ΔV_seNo
It can be obtained by sequentially updating. Further, in the above-mentioned embodiment, the amplification factor is small.
Clear the fail counter to 0 while switching to
However, the failure detection was canceled at all, but the amplification factor was small.
Hold the count value of the fail counter
It is also possible to keep it.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram corresponding to the scope of the claims of the present invention. FIG. 2 is a block diagram showing an embodiment of the present invention. FIG. 3 is a timing chart of arithmetic output used for explaining the operation of the apparatus shown in FIG. FIG. 4 is a flowchart showing various processing procedures in the microcomputer of the apparatus shown in FIG. 5 is a diagram showing A / D conversion timing according to the flowchart shown in FIG. 6; FIG. 6 is a flowchart showing various processing procedures in the microcomputer of the apparatus shown in FIG. FIG. 7 is a flowchart showing various processing procedures in the microcomputer of the apparatus shown in FIG. FIG. 8 is a diagram for explaining the calculation of the maximum value according to the flowchart shown in FIG. 4; 9 is a characteristic diagram showing cylinder-by-cylinder discrimination output signals and detected signals for fail discrimination, which are obtained by knock sensor output in the apparatus shown in FIG. 10 is a flowchart showing various processing procedures in the microcomputer of the apparatus shown in FIG. 11 is a flowchart showing various processing procedures in the microcomputer of the apparatus shown in FIG. FIG. 12 is a block diagram showing a main configuration of another embodiment of the device of the present invention. [Explanation of reference numerals] 1 knock sensor 2 as nonch detecting means 2 electronic control unit for engine control 3 igniter 4 injectors 22, 23 amplifier 24 as amplifying means 24 microcomputer

Claims (1)

Claims (1) Knock detection means for detecting knock generated in an internal combustion engine, amplification means for amplifying the output of the knock detection means, and knock determination for creating a knock determination level by the output of the amplification means Level creating means, knock determining means for comparing the knock determining level of the knock determining level creating means with the output of the amplifying means, and the ignition timing and the air-fuel ratio according to the determination result of the knock determining means. ,
Knock control factor control means for controlling a knock control factor such as intake pressure; and amplification factor varying means for stepwise changing the amplification factor of the amplification means in a plurality of stages according to the knock determination level of the knock determination level creating means. A knock control device for an internal combustion engine, comprising: (2) The knock for internal combustion engine according to claim 1, wherein the amplifying means comprises a plurality of amplifiers connected in series, and outputs of amplification factors of a plurality of stages are taken out from each of the front stage amplifier and the rear stage amplifier. Control device. (3) The knock control device for an internal combustion engine according to claim 1 or 2, wherein the amplification factor changed stepwise in the plurality of stages is set to a power of two.