JPS6216365B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting knocking in an internal combustion engine.

Conventionally, when designing internal combustion engines installed in automobiles, various considerations have been made from the perspective of improving performance. So that
The so-called MBT (Minimum advance for Best
A negative pressure advance mechanism and a centrifugal advance mechanism are used to obtain ignition timing characteristics close to those of Torque.

However, in the relatively low speed range of a normal spark-ignition internal combustion engine, the ignition timing limit at which knocking occurs (varies depending on the type of engine, fuel octane number, etc.) is on the later side than MBT. Therefore, if the ignition timing is set to MBT, knocking will occur. Therefore, in order to bring the ignition timing as close to MBT as possible without knocking in a relatively low speed range, it is best to set the ignition timing to the above-mentioned limit ignition timing, but in reality, However, due to the effects of changes in the engine over time and variations in the octane number of the fuel, it is necessary to set the ignition timing later than the above-mentioned limit ignition timing with some margin, resulting in a decrease in fuel efficiency and output performance. The reality is that The rate of decrease in fuel efficiency and output performance due to delaying the ignition timing is particularly large in turbocharged engines and high compression ratio engines, which have attracted attention in recent years as a means of improving fuel efficiency and output performance. This has become a problem.

Furthermore, even if the ignition timing is set later than the above-mentioned limit ignition timing, there is a possibility that knocking may occur depending on the driving conditions of the vehicle, the operating conditions of the engine, and the environmental conditions. The reality is that it is not possible to completely avoid knot kings.

Further, delaying the ignition timing to prevent knocking in such a case would result in a significant drop in the fuel efficiency and output performance of the engine, which would be impractical.

Therefore, the ignition timing is usually controlled using a negative pressure advance mechanism or a centrifugal advance mechanism that has the same ignition timing characteristics as before or slightly advanced ignition timing characteristics, and only when knocking occurs, For example, a device that avoids knocking by retarding the ignition timing from the normal ignition timing is disclosed in the U.S. Patent No.
This was previously proposed in the specification of No. 4002155.

This type of ignition timing control device starts operation by detecting engine knocking, but the knocking detection means for this purpose is the one disclosed in the above-mentioned U.S. patent specification. The number of times the knocking frequency component signal exceeds a reference level is counted, and knocking is determined based on the size of the counted number, so it is easily affected by noise, and in order to reliably determine knocking, additional Since the knocking frequency component signal must be compared with a higher reference level, the structure becomes complicated and the operation becomes unreliable.

The present invention was invented in view of the above-mentioned conventional situation, and the present invention is based on rectifying signals in the knocking frequency range from a vibration sensor that converts vibration components related to engine sound or pressure, etc. into electrical signals, and rectifying the signals from the vibration sensor. The system is configured to compare the smoothed smoothed level signal, integrate the comparison output signal, compare the integrated signal with a reference level, and output a knocking determination signal. The above-mentioned problem is solved by resetting the integral signal every time the signal is output, and in addition, knocking detection with good responsiveness is achieved by outputting a knocking judgment signal at a frequency according to the strength of knocking. The aim is to provide equipment.

The present invention will be explained below based on the drawings.

FIG. 1 is an overall block diagram of an ignition timing control system equipped with a knocking detection device 1 according to the present invention, which is composed of a knocking detection device 1 and an ignition timing control section 2. As shown in FIG.

The knocking detection device 1 includes a vibration sensor 11,
It consists of a sensor processing circuit 100, a smoothing circuit 200, a comparison circuit 300, an integration circuit 400, a knocking determination circuit 500, and a reset circuit 600.

On the other hand, the ignition timing control section 2 includes an arithmetic circuit 700 that receives the signal from the knocking detection device 1, determines the amount of retardation and the amount of advance, and generates a control voltage corresponding to the amount, and an arithmetic circuit 700 that receives the signal from the knocking detection device 1. An ignition reference signal input section 12 into which an ignition reference signal from a breaker point of a tributator or the like is input, a frequency/voltage conversion circuit 800 that generates a voltage corresponding to the engine speed based on this ignition reference signal, and an ignition reference An equal advance angle control circuit 900 that receives signals and control voltage from the calculation circuit 700 to determine the actual ignition timing, and an ignition coil drive circuit that receives signals from this circuit and outputs a drive signal to the ignition coil 13. It consists of 1000.

The vibration sensor 11 is constructed by, for example, fixing a thin plate-shaped piezoelectric element with silver coating electrodes formed on both sides to a metal disk using a conductive adhesive, and fixing the center of this metal disk to a support base of a case. The sensor uses a piezoelectric element to convert vibrations of a metal disk caused by engine vibrations into electrical signals. The resonant frequency of the metal disc is set in the knocking frequency range of the engine (for example, 6.5 KHz to 8.5 KHz) to form a resonant type sensor so that vibration components in the knocking frequency range can be amplified and extracted. In addition, as the vibration sensor 11, it is also possible to use a resonance type sensor that detects the pressure inside the combustion chamber of the engine and the sound accompanying combustion and has a similar resonance frequency.

The electrical signal from the vibration sensor 11 contains a low-frequency vibration component that becomes a disturbance signal in addition to the amplified vibration component in the knocking frequency range of the engine, so the sensor processing circuit 100 processes this disturbance signal. After removal, amplification and rectification are performed. Although this rectification will be described as half-wave rectification in the example described below, it goes without saying that full-wave rectification may also be used.
In addition, the vibration sensor 11 is not limited to a resonance type sensor.
It goes without saying that all frequency components may be converted into electrical signals, and the resulting signals may be passed through a bandpass filter to obtain a signal of vibration components in the knocking frequency range.

The smoothing circuit 200 smoothes the rectified signal to obtain a smoothed level, and inputs this smoothed level signal together with the knocking frequency range signal from the sensor processing circuit 100 to the comparison circuit 300, which compares both. .

The integration circuit 400 integrates the comparison output signal from the comparison circuit 300, and the knocking determination circuit 500
Output to. The knocking determination circuit 500 compares this integral signal with a reference level, and outputs a knocking determination signal when the integral signal exceeds the reference level. Note that the integration circuit 400 is connected to the reset circuit 6.
00 for each predetermined crank angle width, for example,
It is reset every ignition cycle, and it is determined whether or not knocking has occurred within this interval. Further, in order to output the knocking judgment signal at a frequency corresponding to the knocking intensity, the integrating circuit 400 is reset by a reset circuit 600 every time the knocking judgment signal is output. .

As described above, when the knocking detection device 1 of the present invention outputs a knocking determination signal from the knocking determination circuit 500, this signal triggers the arithmetic circuit 700 of the ignition timing control section 2. This arithmetic circuit 700 retards the ignition timing by a predetermined amount each time a trigger signal is input, and maintains the normal ignition timing (based on the ignition reference signal) using a predetermined function while the trigger signal is not input.
Calculation is performed to generate a control voltage to advance the angle toward.

On the other hand, the frequency/voltage conversion circuit 800 generates a voltage corresponding to the engine speed based on the ignition reference signal from the input section 12. This voltage is input to the constant advance angle control circuit 900 together with the control voltage from the arithmetic circuit 700 and the ignition reference signal from the input section 12. The equal advance angle control circuit 900 delays the normal ignition timing according to each input signal, outputs the corrected ignition timing signal to the ignition coil drive circuit 1000, and then delays the ignition coil 13 by a predetermined angle from the normal one. Can be driven.

Next, details of each of the above parts will be explained.

FIG. 2 shows an example of the configuration of the sensor processing circuit 100, which is a filter circuit consisting of resistors R101, R102, R103 and a capacitor C101, which filters out low frequency components that become interference signals from the electric signal of frequency components equivalent to knocking from the vibration sensor 1. Remove. The electrical signal in the knocking frequency range (for example, 6.5 to 8.5 KHz) from which the interfering signal has been removed is
For example, the signal shown at 5 in FIG. 6 generates large signals that are considered to be knocking at times A and B.

However, the signal from the vibration sensor 11 also includes a vibration component that steadily occurs as the engine burns, and the amplitude of this vibration component varies depending on the engine operating state (engine speed, load state, etc.). ), there is a problem in comparing the signal 5 with a certain reference level and determining that vibration components exceeding this level are due to knocking. That is, the vibration component exceeding the reference level may be caused by the engine operating state. In this sense, the reference level with which the signal 5 is compared needs to be changed depending on the driving condition.
In the present invention, for this purpose, the knocking vibration component of the signal 5 is detected as described below.

That is, the signal 5 that has passed through the filter circuit is passed through the operational amplifier OP101 having resistors R104, R105, and R106, and the resistors R108 and R1.
The signal is supplied to a half-wave rectifier circuit formed by connecting an operational amplifier OP102 having 0.09 and R110 via a diode D101 and a resistor R107, and the signal half-wave rectified by the diode D101 is amplified as specified. At this time, operational amplifier OP10
1. Since a signal is input to the positive side of OP 102, an operating waveform obtained by half-wave rectification of the signal 5 is outputted to terminal 10, as shown by the same reference numeral as this terminal in FIG.

FIG. 3 shows an example of the configuration of the smoothing circuit 200, in which the terminal 10
The operating waveform from resistor R201 and capacitor C
201, and the smoothed value is amplified to a predetermined level by an amplifier OP201 having resistors R202 and R203, and the smoothing level shown by the same reference numeral as this terminal in FIG. 6 is obtained from the terminal 20. Output a signal.

FIG. 4 shows an example of the configuration of the comparison circuit 300, in which operating waveforms and smoothed level signals from terminals 10 and 20 are compared with each other. For this purpose, an operational amplifier OP301 having a resistor R302 is provided, the smoothed level signal from the terminal 20 is inputted to its positive input terminal via the resistor R301, and the operating waveform from the terminal 10 is inputted as is to its negative input terminal.
Thus, both these signals are connected to the operational amplifier OP301.
A comparison output signal (pulse signal) from terminal 30 is shown with the same reference numeral as this terminal in FIG.
is output. This pulse signal is normally at a high level during the period when the signal from terminal 10 exceeds the smooth level signal from terminal 20;
(reflecting the magnitude of the signal from the source), shall be at a low level. Note that if all the negative pulses of the pulse signal output from the terminal 30 are determined to be knocking, it will be an erroneous determination because the signal from the vibration sensor 1 contains various pseudo-knocking vibrations including ignition noise.

Therefore, in the present invention, the integrated signal of the negative polarity pulse is compared with a reference level within an interval corresponding to a predetermined crank angle width, for example, within an interval corresponding to one ignition cycle, using a circuit described below.
A knocking determination signal is output.
In order to improve the responsiveness of the knocking detection device, the integral signal is reset each time the integral signal exceeds a reference level, that is, each time a knocking determination signal is output. For this purpose, an integrating circuit 400, a knocking determination circuit 500,
The reset circuit 600 is configured as shown in FIG. 5, for example.

The integration circuit 400 includes an integrator OP401 including a diode D401, resistors R401, R402, R403, and a feedback capacitor C401, and a switch S40 that shorts the feedback capacitor C401.
It consists of 1. Here, the above-mentioned comparison circuit 3
A pulse signal generated at terminal 30 by 00, for example, a pulse signal shown with the same reference numeral as this terminal in FIG. The negative polarity pulse is integrated, and an integrated signal having a stepped waveform is output from the terminal 41, which is shown with the same reference numerals as this terminal in FIG.

This integral signal is sent to the knocking judgment circuit 5 in the next stage.
00, i.e. resistors R501, R502, R5
Operational amplifier with 04 and feedback resistor R503
Input to the negative terminal of OP501, resistor R
501 and R502, and when the integrated signal exceeds the reference level, a knocking determination signal (shown as 40 in FIG. 7) is sent to the terminal 40. ) occurs. This knocking judgment signal is sent to the reset circuit 6.
00 and is input to the arithmetic circuit 700.

In the reset circuit 600, this knocking determination signal is input to a first-order lag circuit consisting of a resistor R612 and a capacitor C603 to generate a first-order lag signal (indicated by 43 in FIG. 7) at a terminal 43. , R611 is compared with a predetermined reference level (indicated by 48 in FIG. 7) by a comparator OP603.
A comparison pulse signal (indicated by 44 in FIG. 7) is generated at a terminal 44 to which a power supply voltage is applied via.
This comparison pulse signal is differentiated by a differentiating circuit consisting of a capacitor C602, a resistor R608, and a diode D602. This differential signal is compared by a comparator OP602 with a predetermined reference level divided by resistors R606 and R607, so that a predetermined level is applied to the output terminal 45 to which the power supply voltage is applied via resistor R605. A time width pulse signal (indicated by 45 in FIG. 7) is generated.

This pulse signal is input to the OR gate G601, and is output from the output terminal 47 as a reset signal (indicated by 47 in FIG. 7) for closing the switch SW400 of the integrating circuit 400 and resetting the integrator OP401. On the other hand, an ignition reference signal (indicated by 49 in FIG. 7) is inputted to the other input terminal 49 of the reset circuit from the pick-up of the distributor, etc. Differentiated by circuit. This differential signal is compared by the comparator OP601 with a predetermined reference level divided by the resistors R602 and R603, so that the ignition is applied to the output terminal 46 to which the power supply voltage is applied via the resistor R604. A pulse signal (indicated by 46 in FIG. 7) having a predetermined time width is generated from the rising edge of the reference signal. This pulse signal, like the pulse signal 45 described above, is input to the OR gate G601 and output from the output terminal 47 to the integrating circuit 400 as a reset signal.

To explain the operation of each of the above circuits in more detail using FIG. 7, when the ignition reference signal 49 rises at time _t1 , the reset signal 47 is generated by the reset circuit 600, and the integration circuit 400 is reset. Then, the integration operation is started. And terminal 3
The negative pulse in section C associated with knocking occurring at 0 is integrated, and at time _t2 when the integrated value 41 exceeds the reference level 42, the knocking determination signal 40 is output. This knocking judgment signal 4
0 is input to an arithmetic circuit 700, which will be described later, and is also input to a reset circuit 600, which generates a reset signal 47 at time _t3 , which is a predetermined time elapsed from time _t2 , and outputs a reset signal 47 to the integration circuit 400. is reset.

The integrating operation of the integrating circuit 400 is resumed from time _t3 , but since the knocking strength in section C is relatively small, the integral value 41 never exceeds the reference level 42 again, and the knocking judgment signal 40 It will not be output again.

Next, when the ignition reference signal rises again at time _t4 ,
In the same way as the previous time, the integration circuit 400 is reset and the integration of the negative polarity pulse in section D accompanying knocking is started. Since the knocking strength in section D is relatively large, the integral value exceeds the reference level 42 at time _t5 , and the knocking determination signal 4
0 is output, and the integration operation of the integration circuit 400 is restarted at time t ₆ . At time t ₇ , the integrated value exceeds the reference level 42 again, and the knocking determination signal 40 is output again. Thereafter, the integrating operation of the integrating circuit 400 is restarted at time _t8 , but the integrated value 41 no longer exceeds the reference level 42 in section D.

That is, within one ignition interval including the interval C where the knocking strength is relatively small, one pulse of the knocking determination signal 40 is generated, and within one ignition interval including the interval D where the knocking strength is relatively large, the knocking determination signal 40 is as follows. Two pulses will be generated. Therefore, as described above, the knocking detection device 1 of the present invention detects every predetermined crank angle width, for example,
The number of knocking determination signals corresponding to the knocking intensity is output for each ignition interval. This knocking determination signal 40 is input to the arithmetic circuit 700 of the ignition timing control section 2, as described above.

The ignition timing control section 2 will be explained in detail below.
FIG. 8 shows an example of the configuration of the arithmetic circuit 700, which includes an amplifier OP701, a capacitor C70,
1. Resistors R701 to R703 and diode D7
A monostable multivibrator made of 01 is provided at the front stage. This monostable multivibrator is triggered when the knocking determination signal 40 changes from a high level to a low level, and outputs a waveform shown with the same symbol in FIG. 10 from a terminal 72. The next stage of the monostable multivibrator is the amplifier OP702, C702.
and R704 to R707, which are connected to diodes D70 with different polarities.
2, connect to terminal 72 via D703. Thus, the integrator can set the time constants for both integration directions independently, with the time constant in the down direction being set by resistor R704 and capacitor C702, and the time constant in the up direction being set by resistor R705 and capacitor C702, respectively. It's decided. Note that the diodes D704 and D705 and the resistors R708 to R711 constitute a limiting circuit that limits the operating range of the integrator to between the power supply voltage +V and 0. Therefore, when the integrator receives the signal from the terminal 72, it slowly rises while this signal is at a low level, and resistors R710 and R7
A signal that saturates at the upper limit determined by 11 and rapidly decreases while at a high level is connected to terminal 51.
can be output to. This signal is shown with the same reference numerals as the corresponding terminal 71 in FIG. If the level occurs frequently, the signal 51 will step down and resistors R708, R70
It saturates at the lower limit determined by 9.

Note that the high level time of the signal 72 is a fixed time determined by the monostable multivibrator described above, and the amount that the integrator integrates in the downward direction at one time with this high level signal is constant, and this can be expressed as, for example,
It is best to set it to the equivalent of 0.5 degrees of retardation. At this time, the integrator output 71 corresponds to the number of high level occurrences of the signal 72, so it can be used as an ignition timing correction value.

A polarity inversion amplifier circuit consisting of resistors R712 to R719 and an operational amplifier OP703 is provided at the next stage of the integrator, and this circuit makes the input integrator output 71 equal to the signal of the equiadvanced angle control circuit 900. Therefore, the polarity is changed and the level is adjusted, and a signal shown with the same reference numeral as this terminal in FIG. 10 is outputted from the terminal 70.

FIG. 9 shows a configuration example of the frequency/voltage conversion circuit 800. This block is a circuit part that converts the engine speed into voltage, for example, the ignition reference signal 12.
capacitor C801, resistor R801~R80
4. Diode D801 and operational amplifier OP80
The monostable multivibrator configured by 1 converts it into a pulse signal of a constant width, and this pulse signal is transmitted to the next stage of resistors R805 to R815, capacitor C802, and operational amplifiers OP802 and OP803.
The voltage is converted into an analog voltage by a smoothing circuit configured as shown in FIG. Thus, this analog voltage has a value corresponding to the engine speed.

FIG. 11 shows a configuration example of the equal advance angle control circuit 900. This block consists of transistors T901 to T9.
03, resistors R901 to R904 and capacitor C
901, which differentiates the ignition reference signal 12 to obtain the ignition reference signal 12.
The transistor T903 is made conductive at each rise of
Short-circuit capacitor C902 and reset.
Immediately after this reset, the transistor T903 becomes non-conductive, so the capacitor C902 receives the analog voltage (engine speed) from the terminal 80.
The battery is charged with a current proportional to the engine speed via the voltage/current conversion circuit 93. Therefore, a voltage appears at terminal 91, which is indicated by the same reference numeral as this terminal in FIG. However, as mentioned above, since the charging current of capacitor C902 is proportional to the engine speed, when the engine speed is 2400 rpm,
Figures 13a and 13 show the times of 1200rpm and 1200rpm, respectively.
As is clear from the comparison in FIG. b, the voltage waveform 91 in terms of crank angle is constant regardless of the engine speed, and is a uniform advance integral waveform.

The voltage/current conversion circuit 93 has a configuration as shown in FIG. 12, and in this circuit, the voltage 80 proportional to the rotational speed is supplied to the positive input terminal of the differential amplifier OP950 via a resistor R952.
Now, for convenience of explanation, the value of voltage 80 is V ₆₀ ,
The output voltage of terminal 95 is V ₉₅ , and the differential amplifier OP950
Let the voltage at the positive input terminal be V ₊ , the voltage at the negative input terminal V _- , and the voltage at the output terminal V ₂ ,
Assuming that the resistance values of resistors R950 to R953 are the same, the voltage V ₊ is the difference between differential amplifier OP951 and resistor R
Since there is a feedback circuit including 953, V ₈₀ +V ₉₅ /2
Therefore, the voltage V _- becomes V ₂ /2. Also, the differential amplifier OP750 has an output V ₂ of V ₈₀ in the presence of the feedback circuit described above.
It operates so that +V ₉₅ . Therefore, resistance R9
The potential difference between both ends of 54 becomes V ₈₀ +V ₉₅ -V ₉₅ =V ₈₀ , and the current passing through this resistor, that is, the output current at terminal 75 becomes V ₈₀ /R954, which is always equal to the input voltage 80 proportional to the engine speed. Proportional. Therefore, the output current of the terminal 95 is controlled by the input voltage 80 and has a value that is always proportional to the engine speed, and the charging speed of the capacitor C902 charged with this current is determined by the engine speed, and the linear progression An angular integral waveform 71 can be obtained.

The equiadvanced integral waveform from the terminal 91 is input to the positive input terminal of the operational amplifier OP901, and the signal 70 is input to the negative input terminal thereof. Operational amplifier OP901 receives both these signals 9
1 and 70, a retard signal having a negative polarity pulse with a time width such that the signal 91 is lower than the level of the signal 70 is output from the terminal 92, as is clear from FIG. Corresponding terminal 92 to the diagram
Indicated by the same symbol. Note that if the equal advance angle integral waveform 91 is set to saturate at a crank angle of 30 degrees as shown in FIG. 10, the negative pulse width of the retard signal 92 will never exceed a crank angle of 30 degrees. The amount of retardation of the ignition timing can also be caused by a calculation malfunction.
This prevents the angle from exceeding 30 degrees and prevents engine stalling.

The retard signal 92 is the ignition reference signal 12.
and is input to AND gate G901, and this AND gate outputs terminal 9 by ANDing both input signals.
0 outputs a corrected ignition timing signal indicated by the same reference numeral as this terminal in FIG. This corrected ignition timing signal drives the ignition coil 13 to the corrected ignition timing via the ignition coil drive circuit 1000 shown in FIG. 1, thereby suppressing the occurrence of knocking.

The knocking determination signal obtained by the apparatus of the present invention as described above can be used, for example, to control the ignition timing in this way, but other control signals such as fuel injection amount and injection timing may be used in response to various other requests. Of course, it can also be used as an EGR control signal.

As explained above, according to the knocking detection device of the present invention, a signal in the knocking frequency range from the vibration sensor is compared with a smoothed level signal obtained by rectifying and smoothing the signal from the vibration sensor, and this comparison output signal is integrated. The integrated signal is compared with a reference level to output a knocking judgment signal, and the integrated signal is reset every predetermined crank angle width and every time the knocking judgment signal is output. Since the number of knocking determination signals corresponding to the strength can be obtained, it is possible to obtain a knocking detection device with extremely good responsiveness.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the knocking detection device of the present invention together with an ignition timing control device that operates based on future signals, Fig. 2 is a circuit diagram showing a sensor processing circuit, and Fig. 3 is a circuit diagram showing a smoothing circuit. , FIG. 4 is a circuit diagram showing the comparison circuit, FIG. 5 is a circuit diagram showing the integrating circuit, knocking judgment circuit, and reset circuit, and FIG. 6 is an explanatory diagram of operating waveforms related to the smoothing circuit and comparison circuit in the device of the present invention. , FIG. 7 is an explanatory diagram of the knocking intensity detection operation waveform by the knocking detection device of the present invention, FIG. 8 is a circuit diagram showing an arithmetic circuit, FIG. 9 is a circuit diagram showing a frequency/voltage conversion circuit, and FIG. An explanatory diagram of the operating waveforms of the advance angle control circuit, Fig. 11 is a circuit diagram showing the equal advance angle control circuit, Fig. 12 is a circuit diagram showing the voltage/current conversion circuit used in the equal advance angle control circuit, Fig. 13 is etc. FIG. 3 is an explanatory diagram of a lead angle integral waveform. 1... Knocking detection device of the present invention, 2... Ignition timing control device, 10... Half-wave rectification signal output terminal,
11... Vibration sensor, 12... Ignition reference signal input terminal, 13... Ignition coil, 20... Smoothing level signal output terminal, 30... Comparison pulse signal output terminal, 40... Knocking judgment signal output terminal, 10
0...Sensor processing circuit, 200...Smoothing circuit, 3
00...Comparison circuit, 400...Integrator circuit, 500
... Knocking judgment circuit, 600 ... Reset circuit, 700 ... Arithmetic circuit, 800 ... Frequency/voltage conversion circuit, 900 ... Equal advance angle control circuit, 100
0...Ignition coil drive circuit.

Claims (1)

[Claims] 1. A knocking detection device for an internal combustion engine, which includes a vibration sensor that converts vibration components such as sound and pressure generated in the engine into electrical signals, and a first vibration sensor that rectifies and smoothes the signals from the vibration sensor. a second circuit that compares the smoothed level signal from this circuit with a signal in the knocking frequency range from the vibration sensor, and a third circuit that integrates the comparison output signal from this circuit.
a fourth circuit that compares the integral signal from this circuit with a reference level signal and outputs a knocking determination signal; 3. A knocking detection device for an internal combustion engine, comprising: a fifth circuit for resetting the third circuit, and is configured to determine knocking based on the presence or absence of the knocking determination signal. 2. The knocking detection device for an internal combustion engine according to claim 1, wherein the second circuit is a circuit that outputs a pulse signal as a comparison output signal. 3. The internal combustion engine according to claim 1, wherein the second circuit is a circuit that outputs, as a comparison output signal, an analog signal corresponding to the extent to which the knocking frequency component signal exceeds the smoothing level signal. Engine knocking detection device.