JPS6321364A - Knocking controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To enable complete knocking detection by mounting both knocking sensors possessing different characteristics among them and a plurality of knocking detecting system containing a frequency filter, a reference voltage generating means. CONSTITUTION:The knocking detecting pulses generated from both a comparator 56 in a primary knocking detecting system 100 and a comparator 66 in a secondary knock detecting system 200 are converted into the OR signals, respectively in an OR circuit 70 and then sent to an integrator 7. Since said integrator 7 generates control voltages according to input pulses, if a knocking is detected from either the primary or the secondary knocking detecting system, the integrator 7 will generate a control voltage to make delay control for the ignition timing so that the engine knocking may be restrained. The respective characteristics of acceleration sensors 51 and 61, frequency filters 52 and 62 and noise level detectors 55 and 65 are changed to different ones in each of the knocking detecting systems so that said characteristics can be modified to the optimum characteristics in respective knocking detecting systems, whereby accurately detecting any knockings in all cylinders of an engine by the characteristics of each of the knocking detecting systems.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a knock control device for an internal combustion engine that suppresses non-king of the internal combustion engine.

[Conventional technology]

Control methods for detecting and suppressing knock generated by the engine include fuel control, ignition timing control, boost pressure control, etc., but the following explanation will be based on ignition timing control, which is the most commonly used control method.

The conventional ignition timing control device for an internal combustion engine shown in FIG. 4 will be described below.

In this figure, 1 is an acceleration sensor attached to the engine and detects the vibration acceleration of the engine, 2 is a frequency filter that passes the signal component of the frequency that is sensitive to knocking among the output signals of the acceleration sensor v1, and 3 is the frequency This is an analog gate that blocks noise that becomes an interference wave for knock detection in the output signal of the filter 2.

Further, the dirt timing controller 4 instructs the analog gate 3 to open or close in accordance with the timing of occurrence of disturbing noise.

The output of this analog gate 3 is sent to a noise level detector 5 and a comparator 6. The noise level detector 5 detects the level of engine mechanical vibration noise other than knocking.

Further, the comparator 6 compares the output voltage of the analog gate 3 and the output voltage of the noise level detector 5, and performs knock detection/9.
A pulse is generated and output to the integrator 7.

The integrator 7 integrates the output signal of the comparator 6 and generates an integrated voltage corresponding to the knocking intensity.

The phase shifter 8 shifts the position of the reference ignition signal in accordance with the output voltage of the integrator 7.

On the other hand, 9 is a rotation signal generator that generates an ignition signal according to a preset ignition advance characteristic.The output of this rotation signal generator 9 is waveform-shaped by a waveform shaping circuit 1O, and at the same time, the ignition coil 12 is energized. The closed circuit angle is controlled.

Further, the switching circuit 11 is configured to intermittently supply power to the ignition coil 12 based on the output signal of the phase shifter 8.

FIG. 5 shows the frequency characteristics of the output signal for acceleration sensor height 1. In this Fig. 5, A is when there is no knocking, B is
is the case where knocking occurs.

The output signal of this acceleration sensor l includes a knock signal (a signal generated due to non-king), mechanical noise of the engine of the rig 1, and famous noise components on the signal transmission path, such as ignition noise. . Comparing characteristics A and B in FIG. 5, it can be seen that the knock signal has unique frequency characteristics.

Although this distribution differs depending on the engine or the mounting position of the acceleration sensor l, there is a clear difference in the distribution depending on the presence or absence of knocking in each case. Therefore, by passing the frequency component of this knock signal, noise of other frequency components can be suppressed, and the knock signal can be detected efficiently.

Figures 6 and 7 show the operating waveforms of each part in Figure 4, and the same symbols indicate the waveforms of the same parts. Figure 6 shows the mode in which engine knocking does not occur, and Figure 7 shows the engine Indicates the mode in which knocking is occurring.

Next, the operation of the ignition timing control device for an internal combustion engine shown in FIG. 4 will be explained. The ignition signal generated by the rotation signal generator 9 in accordance with the ignition timing characteristics set in advance by the rotation of the engine is waveform-shaped by the waveform shaping circuit 10 into opening/closing pulses having a desired closing angle, and then passed through the phase shifter 8. Switching circuit 1
1, the power supply to the ignition coil 12 is intermittent, and the engine is ignited and operated by the ignition voltage of the ignition coil 12 generated when the energizing current is cut off. Engine vibrations occurring during operation of the engine are detected by an acceleration sensor l.

If engine knocking is not occurring, engine vibration due to knocking will not occur, but due to other mechanical vibrations) the output signal of acceleration 7/s1 will be as shown in Figure 6 (
As shown in a), mechanical noise and ignition noise on the signal transmission path occur at the ignition timing F.

By passing this signal through the frequency filter 2, the mechanical noise component is considerably suppressed as shown in Figure 6(b), but since the ignition noise component is strong, it is output at a high level even after passing through the frequency filter 2. may be done.

If this continues, the ignition noise will be mistakenly recognized as a knock signal, so the output of the dirt timing controller 4 (Fig. 6 (C)), which is triggered by the output of the phase shifter 8 from three analog gate manufacturers, will cause the ignition noise to be detected for a certain period of time from the ignition timing. Close that dart and cut out the ignition noise. Therefore, only low-level mechanical noise remains in the output of the analog gate 3, as shown in FIG. 6(d).

On the other hand, the noise level detector 5 responds to changes in the peak value of the output signal of the analog dart 3, and in this case, has the characteristic of being able to respond to relatively gentle changes due to the peak value of normal mechanical noise. A DC voltage slightly higher than the peak value of the noise is generated (the opening in FIG. 6(d)).

Therefore, as shown in FIG. 6(d), since the output of the noise level detector 5 is larger than the average peak value of the output signal of the analog gate 3, a comparator 6 is used to compare them.
As shown in FIG. 6(e), no output is output, and all noise signals are eventually removed.

Therefore, the output voltage of the integrator 7 changes from the phase shift angle (input/output (Figure 7) (2
)), the phase difference of (h)) also becomes zero.

Therefore, the open/close phase of the switching circuit 11 driven by this output, that is, the intermittent phase of energization of the ignition coil 12, is in phase with the reference ignition signal output from the waveform shaping circuit 10, and the ignition timing becomes the reference ignition timing.

In addition, when knocking occurs, the output of the acceleration sensor l includes a knocking signal around a certain time delay from the ignition timing, as shown in FIG. 7(a), and after passing through the frequency filter 2 and analog gate 3. The signal shown in FIG. 7(d) is a signal in which a knock signal is largely superimposed on mechanical noise.

Among the signals that have passed through the analog gate 3, the knock signal has a steep rise, so the response of the output voltage level of the noise level detector 5 to the knock signal is delayed. As a result, since the inputs of the comparator 6 become A and A of FIG. 7(d), a pulse is generated at the output of the comparator 6 as shown in FIG. 7(e).

An integrator 7 integrates the pulse and generates an integrated voltage as shown in FIG. 7(f). Then, the phase shifter 8 outputs the output signal of the waveform shaping circuit 10 according to the output voltage of the integrator 7 (see FIG. 7).
g) (reference ignition signal)) to the delayed side in time, the phase of the output of the phase shifter 8 lags behind the phase of the reference ignition signal of the waveform shaping circuit 100, and as shown in FIG. 7(h). The switching circuit 11 is driven with the phase shown. As a result, the ignition timing is delayed and knocking is suppressed. Eventually, the conditions shown in FIGS. 6 and 7 are repeated to achieve optimal ignition timing control.

[Problem that the invention seeks to solve]

In the conventional device described above, each of the acceleration sensor 1 and the comparator 6 was composed of one piece, and there was one knock detection system.

However, with the recent increase in the output of engines, in engines with six or more cylinders or engines with a so-called V-shaped cylinder block, a single detection system can detect knocks occurring in all cylinders. In some cases, it may not be possible to detect the knock reliably, so a plurality of the knock detection systems described above may be provided.

In this case, there is a problem in that even if a plurality of knock detection systems are simply provided, the knock detection performance is not sufficient.

This invention was made in order to solve this problem, and the knock detection characteristics of each knock detection system are made the best in each detection system, so that the internal combustion engine can uniformly detect knock occurring in all cylinders at a sufficient level. The purpose is to obtain an engine knock control device.

[Failure to solve the problem]

A knock control device for an internal combustion engine according to the present invention is provided with a plurality of knock detection systems having knock sensors, frequency filters, and reference voltage generating means each having different characteristics.

[For production]

In the present invention, the characteristics of each component in each knock detection system are set to the optimum setting n1 for that detection system to ensure knock detection.

〔Example〕

Hereinafter, an embodiment of the knock control device u″f for an internal combustion engine according to the present invention will be described based on the drawings. The parts indicated by reference numerals 4 and 7 to 12 are the same as those shown in FIG. 4, and the parts described below are different from those shown in FIG. 4 and are the parts that characterize the present invention.

That is, in the embodiment shown in FIG. 1, first and second knock detection systems 100 and 200 are provided. This first,
In the second knock detection system 100, 200, 51.
61it, an acceleration sensor that detects the vibration acceleration of the engine (
(corresponds to acceleration sensor vI in FIG. 4).

The output of each acceleration sensor 5], 61 is a frequency filter, 5
2.62, respectively. The frequency filters 52, 62 select and output only the knock signal component from the output of each acceleration sensor 51, 61 (corresponding to the frequency filter 2 in Fig. 4), and these outputs are output to analog darts 53, 63, respectively. I try to do that.

These analog darts 53 and 63 are each frequency filter 5
Among the output signals of 2.62, noise that becomes an interference wave for knock detection is blocked (corresponding to analog dirt 3 in FIG. 4).

The outputs of the analog filters 53 and 63 are sent to noise level detectors 55 and 65, and comparators 56 and 66, respectively.

Noise level detectors 55 and 65 detect the level t of mechanical vibration noise of the engine other than knocking and use it as a reference voltage (noise level detector 5 in Fig. 4).
), the comparators 56 and 66 are respectively analog r-) 53
．． 63 and the output voltage of the noise level detector 55.65 are compared to generate a knock detection noise (fourth
(corresponds to comparator 6 in the figure).

The outputs of both comparators 56 and 66 are sent to an OR circuit 70.

This OR circuit 70 outputs a logical sum signal of knock detection and false pulses from the outputs of both comparators 56 and 66.

In this way, the first knock detection system lOO includes the acceleration sensor 5
1 to a comparator 56, the second knock detection system 200
is composed of an acceleration sensor +j61 to a comparator 66.

In each of the eleventh and second knock detection systems 100 and 200, the basic operation of the block circuits of each configuration is as in the conventional device described above, and the connections between the block circuits are as in FIG. Since the device is the same as that of the present invention, a description of the basic operation of knock detection will be omitted.

This embodiment uses the first and second knock detection systems Zoo, 2.
00, the comparator 56 of the first knock detection system 100 and the second knock detection system 2
The knock detection pulses output from the comparator 66 of 00 are converted into respective OR signals by the OR circuit 70 and input to the integrator 7.

Since the integrator 7 generates a control voltage corresponding to the input pulse like the conventional device (FIG. 4), even if knock is detected in either of the first and second knock detection systems 100 and 200, the integrator A control voltage is generated from 7, the ignition timing is retarded, and engine knock is suppressed.

By the way, the detection signals of the acceleration sensors 51 and 61 change depending on the mounting position of the engine as described above, so they are basically not the same.

This is because the knock signal of the engine is often a component of several KHz to 10 KHz, and this frequency belongs to the high frequency in the vibration characteristics of the cylinder block of the engine and exhibits very delicate characteristics.

That is, each detection signal of the acceleration sensor 51, 61 has the frequency characteristic of the engine noise signal and knock signal as shown in FIG. 5, and the knock component appears at the same frequency and level with respect to the noise component between each detection signal. Then, the above 1. The desired knock detection can be achieved by simply configuring two second knock detection systems lO0°200 with exactly the same characteristics (by providing two block circuits for each side).

However, since the actual detection signals are slightly different from each other in terms of frequency or level, when the characteristics of the constituent block circuits of the above two types of knock detection systems are the same and have exactly the same detection characteristics, the knock detection is rarely the best.

For example, if the frequency component of the detection signal from the acceleration sensor 51 has the characteristics shown in FIG. 5 in the presence or absence of engine knock, then
The frequency component of the detection signal from the acceleration sensor 61 attached to one of the different positions is K as shown in FIG. 2 or 3.

In these figures, characteristic A represents the frequency characteristic when no knock occurs in the engine, and characteristic B represents the frequency characteristic when knock occurs in the engine.

FIG. 2 shows a case where a characteristic B when knock occurs in the engine is different from the frequency characteristic shown in FIG. 5, and the rail of the knock signal is small.

In FIG. 3, the frequency distribution of the knock signal is the same as in FIG. 5, but the level of the noise signal is higher than characteristic A in FIG. 5 when no knock occurs in the engine.

When the detection signals of the acceleration sensors 51 and 61 are different in this way, the frequency filters 52 and 62 must be set to have different frequency selectivities in order to obtain output signals that can reliably detect knock from each input signal. It's not a big deal. Its main characteristic is the center! frequency, center frequency voltage gain, bandwidth, etc.

The center frequency is set to a frequency where there are few noise signal components and many knock signal components, and the frequency selectivity is determined together with the bandwidth setting. Center frequency voltage gain is the voltage amplification factor that sets the output signal to the desired voltage.

In this embodiment, the acceleration sensors 51 and 61 have flat frequency characteristics, and the frequency selectivity is determined by the frequency filter 52.
．． However, if the acceleration sensor has resonance characteristics, it also has this frequency selectivity, so in order to make the frequency selectivity different between the knock detection systems 100 and 200, different resonance characteristics are required. acceleration sensor is required.

As described above, since each input signal and each frequency selectivity of the frequency filters 52 and 62 are different from each other, the voltages (each peak value and its fluctuation) of the noise signal and knock signal of each output signal are different from each other, and the noise The characteristics of each of the level detectors 55, 65 must be optimized for each input signal in order for the comparators 56, 66 to perform reliable knock detection.

That is, the voltage relationship between the two inputs of each of the comparators 56 and 66 is as shown in FIG. 6(d) (when no knock occurs in the engine), and 7th
The characteristics of each of the noise level detectors 55 and 65 must be optimized for each input signal so that the relationship shown in FIG.

The characteristics of this noise level detector 55, 65 include offset voltage and voltage gain. The offset voltage represents the output voltage when there is no input, and the voltage gain represents the amplification factor of the input signal.

As explained above, when the acceleration sensors 51.61 are installed at different positions, the characteristics of each detection signal are different, so the frequency filter 52.62 or the noise level detector 5
Unless each of the characteristics of 5.65 is made different for each knock detection system, it will not be possible to make each knock detection system optimal in its ability to perform knock detection reliably.

When the acceleration sensors 51 and 61 have resonance characteristics, it is necessary to make the resonance characteristics different from each other.

〔Effect of the invention〕

As explained above, this invention detects engine knock information with a knock sensor, selects and outputs knock signal components from this knock information with a frequency filter, creates a reference voltage for knock detection from this output, and uses this reference voltage and frequency When a device that detects knock occurring in an engine by comparison with the output of a filter is equipped with multiple knock detection systems described above, the specifications of the knock sensor, frequency filter, or circuit that generates the reference voltage described above may be adjusted individually. Since the detection systems have different characteristics, each knock detection system can have optimal characteristics, and the characteristics of each knock detection system can uniformly and reliably detect knock in all cylinders of the engine. This provides excellent practical effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of a knock control device for an internal combustion engine according to the present invention, and FIGS. 2 and 3 are outputs of an acceleration sensor for explaining the operation of the knock control device for an internal combustion engine. FIG. 4 is a block diagram of a conventional knock control device for an internal combustion engine, and FIG. 5 is a diagram showing the output of an acceleration sensor for explaining the operation of the knock control device for an internal combustion engine shown in FIG. , Fig. 6 is an operation waveform diagram of each part in a mode in which the engine does not generate knocking to explain the operation of the knock control device for the internal combustion engine shown in Fig. 4, and Fig. 7 shows the knock control device for the internal combustion engine shown in Fig. 4. FIG. 2 is an operation waveform diagram of each part in a mode in which the engine is generating knocking, for explaining the operation of the control device. 4... Dirt timing controller, 7... Integrator, 8
... Phase shifter, 9... Rotating signal generator, 0... Waveform shaping circuit, 11... Switching circuit, 12...
Ignition coil, 51.61... Acceleration sensor, 52.6
2...Frequency filter, 53.63...Analog gate, 60...OR circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa Figure 2 Figure 3 Figure 1 T〒) N Ft+, 4-nk Takemi Figure 4 Figure 5 Figure 6 Figure 7 Ichiwa Kai - Examination procedure amendment (voluntary) Showa year, month Day 1, Incident Display Patent Application No. 166189/1989 2,
Name of the invention Knock control device for internal combustion engine 3, Person making the amendment Representative Moriya Shiki 4, Agent 5 Column for detailed explanation of the invention in the specification subject to the amendment and drawing 6 Contents of the amendment (1) Description Page 8, line 9 Ω Correct "The output has a phase shift" to "The output has a phase shift." (2) In line 15g11 of the same line, after "...", "In Figures 2 and 3, characteristic A when no knock occurs and characteristic A when knock occurs. There was a case where there was a difference in the distribution of the knock signal or noise between B and B (the knock signal frequency was constant), but this is not the only case; there is no significant difference in the distribution of the knock signal and noise, and the knock signal frequency is simply different. "In some cases." is added. . (3) Figures 1 and 2 of the drawings are corrected as shown in the attached sheets. 7. Attached documents catalog correction drawing 1 copy Figure 1

Claims (1)

[Claims] An acceleration sensor that detects vibration acceleration of the engine to obtain knock information, a frequency filter that selects and outputs a knock signal component from the knock information, a reference voltage generation means that generates a reference voltage from the output of this frequency filter, and the frequency filter. control means for detecting engine knock by comparing the output of the engine with a reference voltage and controlling the ignition timing of the engine to suppress knock; A knock detection system for an internal combustion engine, characterized in that a plurality of knock detection systems are formed, and each knock detection system has an acceleration sensor, a frequency filter, or a reference voltage generating means having different characteristics for each knock detection system. Control device.