JPH03141846A - Knocking detecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To perform ignition at each cylinder with optimum ignition timing by operating/setting a background level according to a specified functional equation on the basis of engine load and speed, and performing knocking discrimination on the basis of this background level. CONSTITUTION:A background level operating means operates and sets a background level to be a reference for taking a knocking element out of the detection signal of a knocking sensor according to a specified functional equation on the basis of the detection value of engine load and speed, and on the basis of this, knocking discrimination is performed at a knocking discriminating means. In this case, a functional equation setting means sets the constants in the functional equation in conformity with plural operating conditions so that the background level operated and set from the engine load and speed coincides approximately with a background level obtained by averaging the detection signal by an averaging/setting means. Ignition at each cylinder can be thus performed with the optimum ignition timing.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a knocking detection device for an internal combustion engine, and more particularly to improvement of background level setting that is a reference for extracting a knocking component from a detection signal of a knocking sensor.

<Prior art> When knocking occurs above a predetermined level in an internal combustion engine, not only does the output decrease, but the impact also causes suction and
Some engines are equipped with an ignition timing control device that detects knocking and corrects the ignition timing to promptly avoid knocking since it has a negative effect on exhaust valves and pistons (Japanese Patent Laid-Open No. 58-105036). (Refer to official bulletins, etc.)

In the ignition timing control device having such a knocking correction function, the knocking level is determined by extracting the knocking component from the detection signal from the knocking sensor installed in the engine. For example, when there is an output level that deviates from the background level by more than a predetermined value, this is determined to be knocking and the ignition timing is retarded. I try to do it.

<Problem to be solved by the invention> By the way, the background level (hereinafter referred to as BGL)
It is abbreviated as ), for example, may take a weighted average of the BGL up to the previous time and the latest value of the sensor detection signal level, and set this weighted average result as the updated value of the BGL. If the configuration is such that the detection is performed only in the knocking detection area, which is a high-load area where knocking occurs, the first time the knocking detection area is reached, the BGL that was last set when the knocking detection area was detected last time is used as the initial value. is updated, and knocking is initially determined based on a BGL that is different from the request. In addition, even if the BGL is configured to perform weighted average calculation at all times in an attempt to solve this problem, when accelerating from a low load to a high load where knocking occurs, the BGL is required due to a response delay due to the weighted average. BGL does not match, and in this case as well, there is a problem that the desired knocking discrimination accuracy cannot be obtained at the initial stage of entering the knocking detection area.

In order to solve this problem, the present applicant learns and stores the BGL obtained by constantly averaging the detection signals from the sensor for each driving condition, and uses this learned and memorized value for the first time in the knocking detection area. First, a knocking detection device for an internal combustion engine configured to search for BC and L corresponding to the current operating conditions and use this as an initial value of BGL, and sequentially update BGL based on this initial value to determine knocking. (filed on October 9, 2017).

However, when one knocking sensor detects the occurrence of knocking in multiple cylinders, the distances from each cylinder to the knocking sensor are different, so the BGL also changes depending on the difference in distance. Therefore, when BGL is stored for each operating condition as described above, it is necessary to have a plurality of BGL maps, which increases the required capacity of the RAM of the microcomputer, resulting in an increase in cost.

In addition, in a configuration that learns and stores BGL for each driving condition,
There is a possibility that unlearned areas and learned areas will be mixed, or that there will be a mix of old and new learning results that were learned under different environmental conditions such as humidity, and such BG
Variations in knocking detection accuracy may occur due to differences in the L operating conditions.

The present invention has been made in view of the above problems, and allows the BGL corresponding to the operating conditions of the engine to be set using a small memory capacity, and also allows the BGL corresponding to each operating condition to be updated to the latest environmental conditions. It is an object of the present invention to provide a knocking detection device that can be set accordingly.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. An engine rotation speed detection means for detecting the speed and a background level, which is a reference for extracting the knocking component from the detection signal of the knock sensor, are set to a predetermined value based on the engine load and engine rotation speed detected by each of the detection means. Knocking in an internal combustion engine includes a background level calculation means for calculating and setting according to a functional formula, and a knocking determination means for determining knocking from a detection signal of a knocking sensor based on the background level calculated by the background level calculation means. The detection device can now be configured.

Here, it is preferable that the background level calculation means is provided with a predetermined function equation for each cylinder to calculate the background level based on the engine load and the engine rotation speed.

In addition, as shown in Figure 1, green stone, there is a background level averaging process setting means that averages the detection signal from the knocking sensor to set the background level, and a background level calculation means that calculates the engine load and engine rotation. The constant of the function expression in the background level calculation means is adapted to multiple operating conditions so that the background level calculated based on the speed substantially matches the background level set by the background level average processing setting means. It is preferable to provide a function equation setting means for setting the function equation.

Furthermore, background level calculation in the background level calculation means and knocking determination in the knocking determination means are performed for each cylinder, and the first
It is preferable to provide an ignition timing correcting means for correcting and controlling the ignition timing of the engine for each cylinder in response to the result of knocking discrimination by the knocking discriminating means, as shown in the figure.

<Operation> According to this configuration, the background level calculation means calculates the background level, which is a reference for extracting a knocking component from the detection signal of the knocking sensor attached to the internal combustion engine and detects knocking vibration, based on the engine load. Calculation and setting are performed according to a predetermined functional formula based on the detected value and the engine rotation speed. The knocking determination means is
Knocking is determined from the detection signal of the knocking sensor based on the background level calculated and set according to the functional formula as described above.

Therefore, the background level for each operating area can be set by storing only the functional formula without storing the background level for each operating area divided by engine load and engine rotational speed.

Here, if the background level calculation means is provided with a predetermined function formula for each cylinder that calculates the background level based on the engine load and engine speed as described above, the required When the background level differs from cylinder to cylinder, different background levels can be calculated and set for each cylinder in response to the background level setting request.

Further, the background level averaging processing setting means does not set the background level according to a functional formula like the background level calculation means, but sets the background level by averaging the detection signal from the knocking sensor. .

The background level set here is used to set the constant of the function expression in the background level calculation means. That is, the functional equation setting means calculates and sets the background level according to the functional equation based on the engine load and engine rotation speed, and the background level that is set by averaging the detection signals as described above. Constants in the background level function equation are set to match a plurality of operating conditions so that they substantially match.

Further, the background level is calculated and set for each cylinder, knocking detection is performed for each cylinder based on the background level for each cylinder, and the ignition timing correction means receives the knocking detection results for each of the 20 cylinders. The engine's ignition timing is corrected and controlled for each cylinder. Thereby, the knocking occurrence level can be determined for each cylinder based on the required background level for each cylinder, and based on this, the ignition timing of each cylinder can be controlled to the maximum advance value that can avoid the occurrence of knocking.

<Example> The present invention will be explained in detail below.

In FIG. 2 showing one embodiment, an internal combustion engine 1 includes an air cleaner 2. Intake duct 3. Air is drawn in via the throttle chamber 4 and the intake manifold 5.

An air flow meter 6 is provided in the intake duct 3 to detect the intake air flow iFQ. Throttle chamber 4
is provided with a throttle valve 7 that operates in conjunction with an accelerator pedal (not shown) to control the intake air flow rate Q. The intake manifold 5 has an electromagnetic fuel injection valve 8 for each cylinder.
is provided, and injects fuel into the intake manifold 5, which is pressure-fed from a fuel pump (not shown) and controlled to a predetermined pressure by a pressure regulator.

The fuel injection amount is controlled by a control unit 9 with a built-in microcomputer based on the intake air flow rate Q detected by the air flow meter 6 and the distributor 1.
The basic fuel injection amount T is calculated from the engine rotation speed N calculated based on the signal from the crank angle sensor 10 built into the
By calculating p=KXQ/N (K is a constant) and correcting this basic fuel injection ff1Tp based on the cooling water temperature Tw, etc., the final fuel injection amount Ti is calculated and is equivalent to this fuel injection amount Tt. A required amount of fuel is injected and supplied to the engine 1 by outputting a drive pulse signal having a pulse width of 1 to 1 to the fuel injection valve 8 in synchronization with engine rotation.

Further, each cylinder of the engine 1 is provided with an ignition plug 11, and a high voltage generated by an ignition coil 12 is sequentially applied to these via a distributor 13, thereby igniting a spark to ignite the air-fuel mixture. Ignite and burn. Here, the ignition coil 12 is connected to the attached power transistor 1.
The timing of generation of high voltage is controlled via 2a. Therefore, the ignition timing (ignition advance value) ADV is controlled by controlling the on/off timing of the power transistor 12a using an ignition control signal from the control unit 9.

The control unit 9 searches for an ignition timing ADV corresponding to the operating condition from a map that stores ignition timing ADV in advance for each of a plurality of operating regions divided by the basic fuel injection amount Tp and engine rotational speed N. At the same time, in a predetermined knock detection operation range, a knock sensor 1 detects knock vibration using a piezoelectric element.
Based on the detection signal from 4, it is determined whether or not there is knocking, and advance/retard correction of 3tlIADv is performed at the time of map ignition, and an ignition control signal is output to the power transistor 12a based on the finally set ignition timing ADV. Therefore, the control unit 9 and the knocking sensor 14 constitute a knocking detection device.

Incidentally, the throttle valve 7 is attached with a throttle sensor I5 that detects its opening degree TV○ using a potentiometer.

Here, the knocking detection performed by the control unit 9 and the ignition timing AD based on the knocking detection are performed by the control unit 9.
The V advance/retard angle correction control will be explained according to the programs shown in the flowcharts of FIGS. 3 to 5, respectively.

In this embodiment, the background level calculation means, the knocking determination means 2, the simmering timing correction means, and the background level average processing setting means.

The function as a function equation setting means is provided in the form of software as shown in the flowcharts of FIGS. Since it is calculated, the crank angle sensor (0 corresponds to the engine rotational speed detection means, and furthermore, the basic fuel injection amount 'rp calculated from the intake air flow -IQ and the engine rotational speed N is representative of the engine load in this example) Therefore, the air flow meter 6 and the crank angle sensor 10 correspond to the engine load detection means.

Incidentally, the crank angle sensor 10 measures 180 @ rotations of the crankshaft (BTD) in the 4-cylinder internal combustion engine in this embodiment.
A reference angle signal REF serving as an ignition reference for C70°) and a unit angle signal PO3 for each rotation of the crankshaft l@ or 2° are output.

The program shown in the flowchart of FIG. 3 is executed every time a reference angle signal REF, which serves as an ignition reference for each cylinder, is output from the crank angle sensor IO.

First, step l (indicated as Sl in the figure).

(Similarly below), a value obtained by integrating the detection signal from the knocking sensor 14 over a predetermined integration period is input. still,
Before the integral processing, the detection signal from the knocking sensor 14 is processed by a bandpass filter and a half-wave rectifier circuit, and the detection signal from the knocking sensor 14 is processed for a predetermined period after the compression top dead center of each cylinder (for example, ATDCI).
0" to ADTC60"), and furthermore, the integration results are reset before the next integration period (for example, ADTC70").

In the next step 2, depending on which cylinder the current reference angle signal REF serves as the ignition reference, the integral value of the knocking sensor 14 detection signal manually input in step 1 is the one that detected knocking in that cylinder. (See Figure 6).

When it is determined in step 2 that the current knocking detection is from the #1 cylinder, the process proceeds to step 3.

In step 3, the previously set background level BGLl for the #1 cylinder and the integral value of the knocking sensor 14 detection signal input this time (hereinafter abbreviated as detection output) are assigned a weighting weight of 2. The result of the weighted average is updated and set as a new GL 1. Also, the detection output input in step 1 this time is #1
Set to knock l, which indicates the knocking level of the cylinder.

In step 4, the constant of the functional formula (BCl2-aXN+bXTp) is used to calculate and set the background level BC;L1 for the #1 cylinder according to the functional formula using the basic fuel injection 1tTp and the engine rotation speed N. al,b
A predetermined value is set when l is updated, and the fourth
It is determined whether the count value cntl, which is counted down every predetermined minute time, is zero according to the program shown in the flowchart of the figure.

When the count value cntl is zero, the constant a
A predetermined period of time has passed since the update calculations of l and bl, and in this case, the update calculations of the constants al and bl of the functional formula (BGL1=a1xN+blXTp) for calculating BGLl for the #1 cylinder are performed. In step 5, the flag F1 is set to 1 in order to allow the above-mentioned constant al.

The new and old data of the operating condition parameters used in the bl update calculation are updated.

In step 6, the latest engine rotational speed N and basic fuel injection amount Tp (engine load) are set to N 1114WITp, respectively.
□, and also the B calculated in step 3 this time.
Set GLI to BGLIo. That is, N 1 n
*w indicates that BGLI□ was obtained by performing weighted average processing on the detection signal of the knocking sensor 14 under the operating conditions of T P-a-. Furthermore, until step 6 is executed, N la*w , TPRII-, BGL 1 , .
The previous data set in , respectively, are N 10L+) and T P OLD as the previous data.

BGLIOLI). In this case as well, N1ot
o.

This indicates that BGLIOLD was calculated for the #1 cylinder under the TPOLI operating conditions.

Incidentally, since steps 5 and 6 are not executed until the count value cntl is counted down to zero, at least the count value cntl is a predetermined value between the old and new data updated in step 6. There will be a time interval that it took to count down from to zero, so that N 1-@-, T
Operating conditions represented by p---, N 10LII,
The operating conditions expressed by T P OLD are different.

In the next step 7, it is determined whether or not the current operating condition is in a predetermined high-load operating region in which knocking detection (and ignition correction control based on knocking detection) is performed. It is determined based on the rotation speed N.

Here, when it is determined that the knocking detection area is detected, it is determined in step 8 whether or not the current knocking detection area determination is the first time, and if it is the first time, the process proceeds to step 9, and the BGL3 Using the function formula BGL3←a3XN 10 b 3 X T p to calculate
The latest values of N and 'rp are substituted into the above function equation to set BGL3 for the #3 cylinder, and this BGL3 is set as the final GL used for knocking detection.

Also, if it is determined in step 8 that it is not the first time,
Proceeding to step IO, similarly to step 3, in step 31, the newly set BGL3 as the weighted average result of the non-ranking level of the #3 cylinder and the BGL3 up to the previous time is finally set to the next GL.

The first time the knocking detection area is entered, BC and L3 are calculated according to a predetermined function formula based on N and Tp at that time as described above, and thereafter, BGL3 according to the function formula is used as an initial value. BGL3 is updated by taking a weighted average with the respective knocking levels. Therefore, from the beginning of the knocking detection area, the BGL that matches the operating conditions
Also, when accelerating from a low load to a high load, which is the knocking detection area, the response delay of the weighted average result is reset when the knocking detection area is reached, so there is no response delay. This can prevent the occurrence of Furthermore, in order to set BGL3 suitable for the operating conditions with N and Tp as parameters, a3. You only need to memorize b3, N and T.
BGL for each operating region divided using p as a parameter.
The memory capacity can be significantly saved compared to the case where 3 is stored.

The reason why the BGL for the third cylinder is set when knocking of the #1 cylinder is detected as described above is because the ignition order in the four-cylinder engine of this embodiment is changed from #1 to #3 to #4 as shown in FIG.
→If it is #2, cylinder #3 will be ignited after cylinder #1, and this time the ignition of cylinder #1 has already finished and the knocking level of cylinder #l has been detected as a result. Therefore, the ignition timing is corrected based on the knocking level of the #3 cylinder determined from the previous ignition result of the #3 cylinder so as to avoid knocking of the #3 cylinder to be ignited next.

Once the BGL for determining the knocking level of the #3 cylinder is set, in the next step 11, the above predetermined or higher value is used to determine whether or not the detection output of the knocking sensor 14 indicates a deviation greater than or equal to the predetermined value with respect to the BGL. The slice level SL corresponding to the deviation of is searched from the map based on the engine rotational speed N.

Then, in the next step 12, BGL+SL is compared with knock 3, which corresponds to the knocking level of #3 cylinder, which was sampled when this program was executed immediately after the previous #33 cylinder fire, and It is determined whether engine knocking of a predetermined level or more occurs when #3 cylinder is ignited.

If it is determined that knock 3≦BGL+SL and knocking did not occur in the #3 cylinder last time, step 1
3, a predetermined advance angle correction value (for example, 0.3°) is added to the ignition timing correction value β3 for the #3 cylinder to further correct the ignition timing correction value β3 to the advanced side. The ignition timing correction value β3
is added to the basic ignition timing (basic ignition advance value) ADV found by searching from the map based on the basic fuel injection amount Tp and the engine speed N, as described later, so the ignition timing correction When the value β3 is increased, the ignition timing AD
V will shift to the more advanced angle side.

On the other hand, if it is determined in step 12 that knock 3>BGL+SL and knocking occurred in the #3 cylinder last time, the process proceeds to step 14, and the ignition timing correction value β3 for the #3 cylinder is changed to a predetermined retardation correction value ( For example, subtract 2°),
The ignition timing correction value β3 is corrected to a more retarded side, and the ignition timing ADV is retarded than the previous time using the ignition timing correction value β3 to prevent knocking from occurring in the current ignition.

When the ignition timing correction value β3 for the #3 cylinder is advanced or retarded based on the knocking level when the #3 cylinder was previously ignited as described above, this correction value β3 is used as the ignition timing correction in step 15. Set to β as the final value to be used. In this way, if each cylinder has a BGL for knocking determination and an ignition timing correction value β, each cylinder can be adjusted to correspond to the difference in the required BGL between cylinders and the difference in the optimum ignition timing between cylinders. Ignition can be performed at the most advanced angular position that can avoid knocking.

Further, when it is determined in step 7 that the area is not in the knocking detection area, the process proceeds to step 16, where the β is set to zero, and the ignition is controlled using the basic ignition timing ADV stored in the map without correction. do.

Once the ignition timing correction value β is set, the next step 59
Now, the ignition timing correction value β is added to the basic ignition timing ADV obtained from the map to obtain the final ignition timing ADV.
In the next step 60, the ignition timing ADV set in step 59 is set as the ignition data for the next #3 cylinder. Also, the next step 61
Now output the integral reset signal and #3 will be fired next.
Ensure that the cylinder knocking level is sampled.

In this way, this program, which is executed in synchronization with the reference angle signal REF, first samples the knocking level of the cylinder that was fired just before (the detection output of the knocking sensor 14), and compares this knocking level with the previous one. The BGL for the cylinder is updated by taking a weighted average of the BGL and the BGL. Furthermore, data for determining the constants (a, b) of the functional formula for calculating the BGL of the cylinder based on the operating condition data is sampled every time the count value cnt is counted down to zero, and the data is sampled for at least a predetermined period of time. This allows data to be sampled under two different operating conditions spaced apart.

Furthermore, after performing the above processing on the cylinder that was ignited immediately before, the next cylinder to be ignited is judged for knocking during the previous ignition, and the ignition timing correction value β is set depending on whether or not knocking has occurred. I do.

In the above explanation, only the case immediately after the ignition of the #1 cylinder was explained, but the same control is performed immediately after the ignition of the #2 cylinder, the #3 cylinder, and the #4 cylinder (from step 17 immediately after the #22 cylinder is ignited). Immediately after ignition of cylinders 30 and 43, step 31~
44. Steps 45-58) immediately after #44 cylinder fires.

The program shown in the flowchart of FIG. 5 is executed as a background job (BGJ), and is a constant of a function formula (BGI, -aXN + bXTp) that calculates BGL for each cylinder based on N and Tp. a and b are
The BGL obtained by weighted averaging of sensor outputs under two different driving conditions is determined so that it matches the BGL based on the functional formula, and the final updated data is obtained by weighting the a and b obtained as a result. shall be. As a result, environmental conditions such as atmospheric humidity change from the initial state, and the required BG
When L changes under the same operating conditions, the functional expression can be updated accordingly, and the BGL level change corresponding to the environmental condition change can be simultaneously executed under all operating conditions.

First, in step 81, the latest basic fuel injection amount Tp and engine speed N are determined from a map that stores the basic ignition timing ADV for each operating region divided into a plurality of regions based on the basic fuel injection amount Tp and engine speed N. Search and obtain data corresponding to.

In the next step 82, the BGL for the #l cylinder is set to N and Tp.
A constant (al
, bl), which indicates whether or not to perform update calculations. The flag Fl is set to 1 when the count value cntl is determined to be zero in the program shown in the flowchart of FIG.
When it is determined in step 82 that the flag Fl is 1,
Proceeding to step 83, the flag F1 is set to zero, and in the next step 84, the count value cntl is set to a predetermined value (for example, 50). Therefore, the flag F1 is determined to be 1 again in step 82 only after at least the time period until the count value cntl is counted down to zero according to the flowchart of FIG. 4 has elapsed.

In step 85, a functional formula (BGLI←a IXN
+b I XTp) are determined from data of two different operating conditions sampled in step 6 with a time interval counted by the count value cntl. That is, since N and Tp, which represent two different (old and new) operating conditions, and BGL obtained by weighted average of sensor outputs under those operating conditions are stored, even in BGL1=a IXN+blXTp. , al and bl are determined so as to match the two operating conditions so that GL is calculated similarly.

Specifically, the following simultaneous equations will be solved.

BGL 1. ,,=A I xN 1. ,,+B I
xTp,s.

BGL IoTn = A I XN IQLIll+B
I XTpoLI.

Since the unknown quantities in the above simultaneous equations are only Al and Bl, constants At and Bl that are suitable for at least two different operating conditions are newly set. constant Al,
Bl and the constants al and bl up to the previous time are weighted averaged using weighted weights X respectively, and the results are used as update data for al and bl, so that al and bl are not updated excessively. .

In this way, the constants al and bl in the functional formula for calculating the BGL for the #1 cylinder from N and Tp are the same as the BGL found by weighted averaging of sensor outputs under two different operating conditions. However, rather than using the results as they are, stable al and b are calculated by taking a weighted average of the previous al and bl.
1 settings are updated.

Once al and bl are determined, the BGL for the #1 cylinder can be calculated at any time based on the engine speed N and the basic fuel injection amount Tp at that time, so there is no need to memorize the BGL for each operating condition. Memory capacity can be saved. In addition, as mentioned above, BGL is calculated according to the functional formula exclusively for the #1 cylinder, so when sampling the knocking levels of four cylinders using one knocking sensor 14, the BGL settings can be made that correspond to BGL requirements that vary depending on distance.

As explained above, the functional formula for calculating GL (BGL+
a constant a that determines aXN+bXTp).

The setting of b is done in the same way for other cylinders,
#2 cylinder a2. a3, b3, # for b2, #3 cylinder
A4 for 4 cylinders. b4 is determined in steps 87-101.

The program shown in the flowchart of FIG. 4 is executed every 10 minutes, and the count values cntl to cnt4 are counted down according to this program.

In steps 71, 73, 75, and 77, it is determined whether the count value cntl=cnt4 corresponding to each cylinder is zero, and if it is not zero, steps 72 and 7
It is updated by 1 down at 4°76.78.

Therefore, the count values cntl to cnt4, which are set to predetermined values when the constants a and b of the function expression are updated, are decreased by l every 10m5 in this program, and when they become zero, By setting flags F1 to F4 for each cylinder to 1,
This time, the predetermined value will be set again using the program shown in the flowchart of FIG.

<Effects of the Invention> As explained above, according to the present invention, the background level is calculated and set according to a predetermined functional formula based on the detected values of the engine load and the engine rotation speed. The level can be obtained with a small memory capacity, and by providing the above-mentioned functional expression for each cylinder, it is possible to respond to different background level requirements for each cylinder.

Further, constants in the functional formula are set so that the background level obtained by averaging the detection signals of the knocking sensor and the background level obtained by the functional formula substantially match under a plurality of operating conditions. Therefore, when the required BGL changes even under the same operating conditions due to changes in environmental conditions, the BGL set based on the functional formula can be promptly calibrated in response to this change.

In addition, if BGL is set for each cylinder using a functional formula, knocking is determined for each cylinder, and the ignition timing is corrected for each cylinder based on the determination result for each cylinder, the occurrence of knocking can be detected with high accuracy for each cylinder. As a result, each cylinder can be ignited at the optimum ignition timing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the tank bottom of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the present invention, and FIGS. 3 to 5 are flow charts showing control details in the above embodiment, respectively. FIG. 6 is a time chart showing knocking detection timing in the above embodiment. 1... Internal combustion engine 6... Air flow meter 9...
・Control unit 10...Crank angle sensor 11...Ignition plug 12...Ignition coil 12
a...Power transistor 13...Distributor

Claims (4)

[Claims] (1) A knocking sensor attached to an internal combustion engine that detects knocking vibrations, an engine load detection means for detecting engine load, an engine rotational speed detection means for detecting engine rotational speed, and a knocking sensor that detects knocking from a detection signal of the knocking sensor. The background level, which is the standard for extracting components, is
a background level calculating means for calculating and setting according to a predetermined functional formula based on the detected engine load and engine rotational speed; and a background level calculating means for calculating and setting based on the background level calculated by the background level calculating means from the detection signal of the knocking sensor. A knocking detection device for an internal combustion engine, comprising: a knocking determination means for determining knocking; and a knocking detection device for an internal combustion engine. (2) Knocking in an internal combustion engine according to claim 1, wherein the background level calculation means is provided with a predetermined function formula for each cylinder to calculate the background level based on the engine load and the engine rotation speed. Detection device. (3) Background level averaging processing setting means for setting a background level by averaging the detection signals from the knocking sensor; and the background level calculating means calculates the background level based on the engine load and engine rotation speed. A function formula that is set by adapting the constant of the function formula in the background level calculation means to a plurality of operating conditions so that the background level substantially matches the background level set by the background level average processing setting means. 3. The knocking detection device for an internal combustion engine according to claim 1, further comprising a setting means. (4) performing background level calculation in the background level calculation means and knocking determination in the knocking determination means for each cylinder;
4. The internal combustion engine according to claim 1, further comprising ignition timing correction means for correcting and controlling the ignition timing of the engine for each cylinder in response to the result of the knocking discrimination by the knocking discrimination means. knocking detection device.