WO1988000654A1

WO1988000654A1 - Knock controller of internal combustion engine

Info

Publication number: WO1988000654A1
Application number: PCT/JP1987/000504
Authority: WO
Inventors: Satoshi; Komurasaki
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 1986-07-14
Filing date: 1987-07-14
Publication date: 1988-01-28
Also published as: DE3790397T1; JPS6321364A; JPH076487B2

Abstract

A device in which knock information of an engine is detected by a knock sensor, knock signal components are selectively produced from the knock information through a frequency filter, a reference voltage of knock detection is made from the above output, and knocking generated in the engine is detected by comparing the reference voltage with the output of the frequency filter. A plurality of the above knock detection systems are provided, where the knock sensors, frequency filters and the circuits for producing reference voltages are designed to have characteristics that are different depending upon the individual detection systems. Therefore, optimum characteristics can be obtained in each of the knock detection systems; i.e., the knock detection systems exhibit characteristics to uniformly and reliably detect knocks of all cylinders of an engine.

Description

Specification

Knock control device for internal combustion engine

Technical field

The present invention relates to a knock control device for an internal combustion engine that suppresses knocking of the internal combustion engine.

Background art

Control methods for detecting and suppressing knock generated by the engine include fuel control, ignition timing control, and supercharging pressure control.The following description is based on ignition timing control, which is the most widely used. .

Hereinafter, the conventional ignition timing control device for an internal combustion engine shown in FIG. 1 will be described. 1 in Fig. 1 is an acceleration sensor that is attached to the engine and detects the vibration acceleration of the engine. 2 is the frequency of the output signal of the acceleration sensor 1 that is highly sensitive to knocking. A frequency filter 3 that allows the signal component to pass through is an analog gate that blocks noise that becomes an interference wave in the knock detection of the output signal of the frequency filter 2.

Further, the gate timing controller 4 instructs the opening and closing of the analog gate 3 according to the time of occurrence of the disturbance noise.

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

The comparator 6 compares the output voltage of the analog gate 3 with the output voltage of the noise level detector 5, generates a knock detection pulse, and outputs it to the integrator 7. .

The integrator ⁷ integrates the output pulse of the comparator ⁶ and generates an integrated voltage according 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, reference numeral 9 denotes a rotation signal generator for generating an ignition signal according to a preset ignition advance characteristic. The output of the rotation signal generator 9 is waveform-shaped by a waveform shaping circuit 10; At the same time ignition coil I. ^The control of the closing angle of electricity is performed in the ^{second step} .

Further, squirrel Lee production kitchen grayed circuits 1 1 by the output signal of the Utsurikashiwa device 8 is in the earthenware pots by intermittently feeding the ignition Coil le I ^2.

Fig. 2 shows the frequency characteristics of the output signal of acceleration sensor 1. In FIG. 2, A is the case where there is no knocking, and B is the case where knocking occurs.

The output signal of the acceleration sensor 1 includes a knock signal (a signal generated by knocking), other mechanical noises of the engine, and various noises riding on the signal transmission path. Ingredients, such as ignition noise. Comparing the characteristics A and B of FIG. 2, ₀ it can be seen that the Roh click signal with a specific frequency characteristic This distribution is different depending on the engine or the mounting position of the acceleration sensor 1, but in each case there is a clear difference depending on the presence or absence of knocking. Therefore, by passing the frequency component of the knock signal, the noise of other frequency components can be suppressed, and the knock signal can be detected efficiently.

FIGS. 3 and 4 show the operation waveforms of the respective parts in FIG. 1 and the same reference numerals indicate the waveforms of the same parts, and FIG. 3 shows the mode in which engine knocking does not occur. The figure shows the engine knocking mode.

Next, the operation of the ignition timing control device for an internal combustion engine in FIG. 1 will be described. The ignition signal generated by the rotation signal generator 9 corresponding to the ignition timing characteristic set in advance by the rotation of the engine is waveform-shaped by a waveform shaping circuit 10 into an opening / closing pulse having a desired closing angle. The switching circuit 11 is driven via the phase shifter 8 to interrupt the power supply to the ignition coil 12, and the ignition voltage of the ignition coil 12 generated when the current supplied to the ignition coil 12 is cut off. The organization is ignited and operated. The engine vibration that occurs during operation of this engine is detected by the acceleration sensor 1.

Now, when engine knocking has not occurred, engine vibration due to knocking does not occur, but the output signal of acceleration sensor 1 due to other mechanical vibrations. As shown in Fig. 3. (a), an ignition noise occurs on the signal transmission path at the mechanical noise ゃ ignition timing F. By passing this signal through frequency filter 2, the mechanical noise component is considerably suppressed as shown in Fig. 3 (b), but the ignition noise is reduced. Since the component is strong, it may be output at a large level even after passing through the frequency filter 2.

In this state, the analog noise 3 is output from the gate timing controller 4 which is triggered by the output of the transferer 8, since the ignition noise is erroneously recognized as a knock signal. The gate is closed by a force (Fig. 3 (c)) for a certain period from the ignition timing to shut off the ignition noise. Therefore, only low-level mechanical noise remains at the output of analog gate 3, as shown in Fig. 3 (d).

On the other hand, the noise level detector 5 responds to a change in the beak value of the output signal of the analog gate 3 and, in this case, to a relatively gradual change due to the peak value of the normal mechanical noise. Has a characteristic that can respond and generates a DC voltage slightly higher than the peak value of the mechanical noise (port in Fig. 3 (d)).

Therefore, as shown in FIG. 3 (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, the output of the comparator 6 which compares these outputs is obtained. Nothing is output as shown in Fig. 3 (e), and all the noise signals are eventually removed.

Therefore, the output voltage of the integrator 7 remains zero as shown in FIG. 4 (f), and the phase shift angle by the phase shifter ⁸ (input / output (FIG. 4) ( _g ), (h) The phase difference is also 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, has the same phase as the reference ignition signal of the output of the waveform shaping circuit 10. Thus, the ignition timing becomes the reference ignition timing.

When knocking occurs, the output of acceleration sensor 1 contains a knock signal near a certain time delay from the fire timing as shown in Fig. 4 ( _a ), and the frequency The signal after passing through filter 2 and analog gate 3 is a signal in which the knock signal is greatly superimposed on the mechanical noise as shown in Fig. 4 (d).

Since the knock signal rises steeply among the signals that have passed through the analog gate 3, the response of the output voltage level of the noise level detector 5 to the knock signal is delayed. As a result, the input of the comparator 6 becomes the input and the output of the comparator 6 in FIG. 4 (d), and a pulse is generated in the output of the comparator 6 as shown in FIG. 4 (e).

The integrator 7 integrates the pulse and generates an integrated voltage as shown in FIG. 4 (f). Then, the phase shifter 8 shifts the phase of the output signal (FIG. 4 (g) (reference ignition signal)) of the waveform shaping circuit 10 to a time-delay side in accordance with the output voltage of the integrator 7. Therefore, the output of the transfer unit 8 has a phase delayed from the phase of the reference ignition signal of the waveform shaping circuit 10, and drives the switching circuit 11 with the phase shown in FIG. 4 (h). As a result, the ignition timing is delayed, and the knocking is suppressed. After all, these Figures 3 and 4 Is repeated to perform optimal ignition timing control. In the above-described conventional device, each of the acceleration sensor 1 and the comparator 6 is one, and the knock detection system is one.

However, with the recent increase in engine output, if the engine has more than six cylinders or the engine has a so-called V-shape cylinder block, a single detection system generates all cylinders. Knock may not be detected uniformly and reliably, and there may be multiple

In this case, there is a problem that even if a plurality of knock detection systems are provided, the knock detection performance is not sufficient. This invention has been made to solve such a problem. Therefore, the knock detection characteristics of each knock detection system are optimized in each detection system, and the knock generated in all cylinders is unified. The purpose of the present invention is to obtain a knock control device for an internal combustion engine that can detect a sufficient level.

Disclosure of the invention

A knock control device for an internal combustion engine according to the present invention includes a knock sensor having a knock sensor having different characteristics from each other, a frequency filter, and a plurality of knock detection systems including a reference voltage generation unit. It is.

In the present invention, the characteristics of each component in each knock detection system are designed to be optimal for the detection system, and Knock detection is performed at first.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram of a conventional knock control device for an internal combustion engine, and FIG. 2 is a diagram showing an output of an acceleration sensor for explaining the operation of the knock control device of the internal combustion engine of FIG. FIG. 3 is an operation waveform diagram of each part of the mode in which the engine does not generate knocking for explaining the operation of the knock control device for the internal combustion engine of FIG. 1, and FIG. FIG. 1 is an operation waveform diagram of each part of a mode in which the engine generates knocking for explaining the operation of the knock control device of the internal combustion engine shown in FIG. 5; FIG. 6 and FIG. 7 are block diagrams showing the configuration of an embodiment of the knock control device, and FIGS. 6 and 7 show the acceleration sensor for explaining the operation of the knock control device of the internal combustion engine. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of a knock control device for an internal combustion engine according to the present invention will be described with reference to the drawings. FIG. 5 is a block diagram showing the configuration of the embodiment. The portions indicated by reference numerals 4 and 7 to 12 in FIG. 5 are the same as those in FIG. 1, and the portions described below are different from FIG. 1 and are features of the present invention.

That is, in the embodiment shown in FIG. 5, first and second knock detection systems 100 and 200 are provided. In the first and second knock detection systems 100 and 200, 51 and 61 are engine An acceleration sensor that detects vibration acceleration (corresponding to acceleration sensor 1 in Fig. 1).

The outputs of the acceleration sensors 51 and 61 are sent to frequency filters 52 and 62, respectively. The frequency filters 52 and 62 select and output only the knock signal component from the outputs of the acceleration sensors 51 and 61 (corresponding to the frequency filter 2 in Fig. 1). The signals are output to analog gates 53 and 63, respectively.

These analog gates 53 and 63 block noise that becomes an interference wave for knock detection among the output signals of the frequency filters 52 and ⁶² , respectively (corresponding to analog gate 3 in Fig. 1). )

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

The noise level detectors 55 and 65 each detect the level of mechanical vibration noise of the engine other than the knocking and use it as a reference voltage (corresponding to the noise level detector 5 in Fig. 1). , comparator ⁵ 6, 66 each analyst port Guge DOO 53, 63 of the output voltage and Bruno Lee Zureberu detector 55 compares the 65 output voltage to generate the Roh click detection pulse (comparator of FIG. 1 Equivalent to 6)

The outputs of the comparators 56 and 66 are sent to the OR circuit 70. This 0 R circuit 0 is a knock detection pulse from the outputs of both comparators 56 and 66. Output the logical OR signal of the signals.

As described above, the first knock detection system 100 is composed of the acceleration sensor 51 to the comparator 56, and the second knock detection system 200 is composed of the acceleration sensor S1 to the comparator. .

In the first and second knock detection systems 100 and 200, the basic operation of the block circuit of each configuration is the same as that of the conventional device described above, and the connection between the block circuits is also the same. As shown in Fig. 5, it is the same as the conventional device in Fig. 1, and the description of the basic operation of knock detection is omitted.

This embodiment has two knock detection systems of the first and second knock detection systems 100 and 200, and the comparator 56 of the first knock detection system 100 and the second knock detection system 100 have the same function. The knock detection pulse output from the comparator 66 of the second knock detection system 200 is ORed by an OR circuit 70 and input to the integrator 7.

Since the integrator 7 generates a control voltage corresponding to the input pulse, similarly to the conventional device (FIG. 1), the knock is detected in either of the first and second knock detection systems 100 and 200. Even if it is detected, a control voltage is generated from the integrator 7, the ignition timing is retarded, and the knock of the engine is suppressed.

At this point, the detection signals of the acceleration sensors 51 and 61 do not basically become the same because they vary depending on the difference in the mounting position of the engine as described above.

Because the knock signal of the engine is often a component of several KHz to 1 OKHz, this frequency is the cylinder block of the engine. This is because it belongs to high frequency in the vibration characteristics of ク and always shows delicate characteristics.

That is, each of the detection signals of the acceleration sensors 51 and 61 has the engine noise signal and the knock signal having the frequency characteristics shown in FIG. 2, and the noise component is knocked between the detection signals. If the components appear at the same frequency at the same frequency, the first and second knock detection systems 100 and 200 have exactly the same characteristics if they are composed of only two systems. (If two block circuits are provided), the desired knock detection can be performed.

However, since the actual detection signals are slightly different from each other in frequency or level, the characteristics of the respective block circuits of the above two types of knock detection systems are the same, and the detection characteristics are exactly the same. In some cases, knock detection is rarely the best. '

For example, if the frequency component of the signal detected by the acceleration sensor 51 is in the characteristic shown in Fig. 2 depending on whether the engine is knocked, the frequency component of the signal detected by the acceleration sensor 61 attached to one of the different positions Is as shown in Fig. 6 or Fig. 7.

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

Fig. 6 shows the case where the characteristic B when knocking occurs in the engine differs from the frequency characteristic of Fig. 2 and the knock signal level is low. . In Fig. 7, the frequency distribution of the knock signal is the same as in Fig. 2, but the level of the noise signal when no knock occurs in the engine is based on the characteristic A in Fig. 2. This is the case.

When the detection signals of the acceleration sensors 51 and 61 are different from each other, the frequency filters 52 and 62 are used to obtain an output signal from each input signal that can reliably perform knock detection. Must be set to have different frequency selectivity. Its main characteristic is the center frequency, the center frequency voltage gain, der bandwidth, etc. "3 ₀

The center frequency is a frequency at which the noise signal component is small and the knock signal component is large, and the frequency selectivity is determined along with the setting of the bandwidth. The center frequency voltage gain is a voltage amplification factor that sets the output signal to a desired voltage.

In Figs. 6 and 7, the difference in the distribution of the knock signal or noise between the characteristic A when no knock occurs and the characteristic B when no knock occurs. However, there is no significant difference in the distribution of the knock signal and the noise, and there is also a case where the knock signal frequency is simply different. is there.

In this embodiment, the acceleration sensors 51 and 61 have the same frequency characteristics, and the frequency selectivity is given to the frequency filters 52 and 62. When using a single acceleration sensor, this frequency selectivity is also provided. In order to make the knock characteristics different among the knock detection systems 1000, acceleration sensors with different resonance characteristics are 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 voltage of the noise signal and the knock signal of each output signal (: Peak values and their fluctuations) are different from each other, and if the latency of each of the noise level detectors 55 and 65 is not optimized for each input signal, the comparators 56 and 66 can reliably detect knocks. Cannot be performed ₀

In other words, the voltage relationship between the two types of inputs of the comparators 56 and 66 is the same as that shown in Fig. 3 (d) for the conventional device shown in Fig. 1 (b). And the characteristics of the noise level detectors 55 and 65 so that there is always a relationship between (a) and (b) (when engine knocks) in Fig. 4 (d). Must be optimized for each input word.

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

As described above, when the acceleration sensors 51 and 61 are mounted at different positions, the characteristics of each detection signal are different, so that the frequency filter 52, 62 or the noise level detector 55, Unless the waiting time of step 5 is made different from each other between the knock detection systems, the knocks are surely knocked in each knock detection system. The characteristics cannot be optimized for detection.

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

Claims

The scope of the claims

An acceleration sensor that obtains knock information by detecting the vibration acceleration of the engine, a frequency filter that selects and outputs a knock signal component from the knock information described above, and a reference that is based on the output of this frequency filter Reference voltage generating means for generating a voltage, controlling the ignition timing of the engine by detecting the knock of the engine based on the comparison between the output of the frequency filter and the reference voltage so as to suppress the knock. A plurality of knock detection systems are formed by respectively providing the acceleration sensor, the frequency filter, and the reference voltage generation means, and the acceleration sensor and the frequency filter of each of the knock detection systems are provided. Alternatively, a knock control device for an internal combustion engine, characterized in that the reference voltage generating means is formed with different characteristics for each knock detection system.