JPH0329978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a knock suppression device for an internal combustion engine that can always perform appropriate knock suppression even when there are large fluctuations in knock-producing factors of the internal combustion engine.

Recently, in order to improve engine efficiency (fuel efficiency) and output,
Knock suppression devices that detect and suppress knocking are being actively developed and adopted. Knocking occurs depending on many factors among engine operating conditions, such as ignition timing, intake air temperature, intake air humidity, air-fuel ratio, and combustion chamber temperature. Of these elements,
In practice, knocking occurs because it is greatly affected by changes in intake air temperature and intake air humidity. Since the intake air temperature and intake air humidity change depending on the season, the state in which knocking occurs changes depending on the season. Furthermore, since the seasons change on a yearly basis, the state of occurrence of knotweed also changes on a yearly basis. In other words, the knocking that occurs in a short period of time under the same operating conditions is of the same degree, and there is no significant difference in the frequency or magnitude of occurrence. Therefore, the control signal required to suppress knocking occurring under the same operating condition is approximately the same over a short period of time.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a knock suppression device for an internal combustion engine that can suppress knocking with good responsiveness.

In order to achieve such an object, the present invention includes an acceleration sensor that detects the vibration acceleration of an internal combustion engine and outputs a vibration signal, and a knocking signal that removes noise signals from this vibration signal and outputs a knocking signal at a level corresponding to the knocking intensity. A means for outputting, a detecting means for detecting a load condition of the internal combustion engine, a detecting means for detecting the rotational speed of the internal combustion engine, and a reference control value for knocking suppression corresponding to the load condition and the rotational speed are stored. The apparatus includes a storage means and a calculation means for outputting a control signal for knocking control from the knocking signal and the reference control value, and will be described in detail below using embodiments.

FIG. 1 is a block diagram showing an embodiment of a knock suppressing device for an internal combustion engine according to the present invention. In the figure, 1 is an ignition signal generator that generates a reference ignition signal according to the rotation of the engine, and 2 receives a reference ignition signal input from this ignition signal generator 1 and performs waveform shaping and closing angle control to obtain a desired signal. ignition pulse with a pulse width of (see Figure 3A, Figure 4A, Figure 5A)
A waveform shaping circuit 3 outputs an ignition pulse inputted from the waveform shaping circuit 2, and 3 is an ignition pulse whose phase is shifted to the delayed side in time according to a control signal from an arithmetic unit, which will be described later. Figure 4D, Figure 5D
Reference numeral 4 is a switch circuit that connects the power supply to the ignition coil 5 in response to the ignition pulse inputted from the phase shifter 3. Reference numeral 6 is a switch circuit that is attached to the engine and detects the vibration acceleration of the engine. , an acceleration sensor 7 that outputs a vibration signal, and 7 selects a knocking component that occurs as the engine knocks based on the vibration signal input from the acceleration sensor 6, and generates a knocking signal at a level corresponding to the knocking intensity (Fig. 3B, A knock detector 8 detects the intake pipe pressure of the engine and resets it by a constant time pulse input from the waveform shaping circuit described below. A pressure sensor 9 outputs a corresponding pressure signal, and digitizes each of the knocking signal input from the knock detector 7 and the pressure signal input from the pressure sensor 8 according to their levels, and outputs the digitized knocking signal and pressure signal. 10 is a waveform shaping circuit that receives the voltage of the drive terminal of the ignition coil 5 and outputs a fixed time pulse at the ignition timing;
Reference numeral 11 denotes a digitized knocking signal inputted from the AD converter 9, which determines the operating state of the engine from the digitized pressure signal inputted from the AD converter 9 and the constant time pulse inputted from the waveform shaping circuit 10. The knocking strength is calculated from the reference control signal V _R stored in the memory described later.
12 is a memory that stores the reference control signal V _R shown in FIG. 2;
It can be modified and memorized.

The ignition signal generator 1, waveform shaping circuit 2, phase shifter 3, switch circuit 4, and ignition coil 5 constitute an igniter section. In addition, the vibration signal output from the acceleration sensor 6 includes a knocking component due to vibration generated due to knocking, as well as a noise signal due to mechanical noise caused by engine operation (for example, a noise signal detected due to the operation of a valve). are included in a superimposed manner. Further, FIG. 2 shows an example of the states of reference control signals stored in the memory 12 corresponding to each operating state. here,
The operating state is determined by the load and rotation speed of the engine, and is divided into rotation speed N ₀ -N ₄ and load L ₀ -L ₄ . Also, the stored reference control signal
For example, V _R is the reference control signal V _R1 for operation from load L _{0 to} load L ₁ in the range of rotation speed N 2 to rotation speed N ₃ , and reference control signal V R for operation from load L ₁ to load L ₂ . _R2 , when operating from load _L2 to load _L3 , the reference control signal is V _R3 , and as the load increases, the reference control signal also increases. Also, Figure 3 A~
Figure 3D shows the waveforms of each part in Figure 1 under operating conditions in which knocking does not occur in the engine, respectively.
4A to 4D show the waveforms of each part in FIG. 1 under operating conditions that require knocking control, and
Figures A to 5D show waveforms of various parts in Figure 1 under operating conditions in which the combustion conditions between the cylinders are slightly different, and control using the reference control signals shown in Figures 4A to 4D results in some insufficient control. shows.

Next, the operation of the knock suppressing device for an internal combustion engine with the above configuration will be explained in Figs. 3A to 3D and Fig. 4A.
This will be explained with reference to FIGS. 4D and 5A to 5D. First, the ignition signal generator 1 generates an ignition signal as the engine rotates. This ignition signal is subjected to waveform shaping and circuit closing angle control by the waveform shaping circuit 2, and an ignition pulse with a predetermined pulse width is output. This ignition pulse is then input to a switch circuit 4 via a phase shifter 3. Therefore, the switch circuit 4 cuts off and on the power supply to the ignition coil 5 in response to the input of this ignition pulse signal. When the power supply to the ignition coil 5 is cut off, an ignition voltage is generated, the engine is ignited, and the engine is put into operation. The pressure sensor 8 detects the intake pipe pressure of the engine and outputs a pressure signal corresponding to the detected pressure. This pressure signal is digitized by the AD converter 9 and input to the calculator 11 as a signal representing the load condition of the engine. In this case, the engine intake pipe pressure sensitively responds to and changes depending on the engine load condition, so it is possible to determine the engine load condition from the level of the pressure signal from the pressure sensor 8 obtained by detecting this intake pipe pressure. can. Further, the acceleration sensor 6 detects vibration acceleration of the engine and outputs a vibration signal. Therefore, the knock detector 7 selects the knocking signal from this vibration signal and outputs the knocking signal at a level corresponding to the knocking intensity. This knocking signal is then digitized by the AD converter 9. Therefore, the computing unit 11 is
The load condition of the engine is determined from the pressure signal from the pressure sensor 8 that is input via the AD converter 9, and the engine rotational speed is determined from the period of the constant time pulse that is input from the waveform shaping circuit 10. The operating state is judged and knocking is detected based on the knocking signal inputted from the knocking detector 7 via the AD converter 9. If knocking is occurring in the engine, the computing unit 11 calculates the operating state of the engine using the pressure signal and fixed time pulses.
The knocking signal is then stored in the memory 12 as a reference control signal for that operating state. Similarly, in each operating state in which a knocking signal is generated in the engine, the knocking signal corresponding to each operating state is stored in the memory 12 as a reference control signal corresponding to each operating state, so that the reference shown in FIG. A map of the control signal V _R can be created.

Next, a description will be given of an operating state in which knocking does not occur in the engine with reference to FIGS. 3A to 3D. In this case, the output of the knocking detector 7 becomes zero as shown in FIG. 3B, and the output of the arithmetic unit 11 also becomes zero as shown in FIG. 3C. As a result, the phase shifter 3 does not perform phase shift control, so the ignition pulse shown in FIG. 3D having the same phase as the ignition pulse output from the waveform shaping circuit 2 shown in FIG. 3A is sent to the switch circuit 4. input. Therefore, the switch circuit 4 cuts off the power supply to the ignition coil 5 corresponding to this ignition pulse.
At reference times t ₁ and t ₂ the ignition coil 5 is de-energized and the ignition voltage is generated.

[] An operating state in which the engine requires knocking control will be described with reference to FIGS. 4A to 4D. In this case, after the ignition at time _t3 , an operating state that requires knocking control occurs, and the computer 1
1 is a pressure sensor 8 that inputs via an AD converter 9
The above-mentioned operating state is determined from the pressure signal level of 1 and the period of the constant time pulse input from the waveform shaping circuit 10, and the reference control signal corresponding to this operating state is stored in the memory 12 as shown in FIG. 4C.
Read and output V _R4 . Therefore, the phase shifter 3 operates as shown in FIG. 4A by inputting the reference control signal V _R4 .
As shown in FIG. 4D, the phase of the ignition pulse inputted from the waveform shaping circuit ₂ shown in FIG. Therefore, the switch circuit 4 adjusts this angle θ ₁
By inputting an ignition pulse phase-shifted by 0.001, the ignition coil 5 is de-energized and the reference times t ₄ and t _{6 are}
Ignition voltage is generated at times t ₅ and t ₇ , which are retarded by an angle θ ₁ , respectively, and the engine is operated. As a result, the occurrence of knocking is eliminated, and the engine can be operated without knocking.

[] If the combustion conditions between the cylinders are slightly different and control using the standard control signal shown in Figure 4C results in a slight lack of control, and low-level knocking continues to occur, the lack of control will be corrected to cause the engine to knock. A case of controlling the operating state to such an extent that no occurrence occurs will be described with reference to FIGS. 5A to 5D. First, immediately after the ignition timing t ₈ , the calculator 11 calculates the level of the pressure signal from the pressure sensor 8 input via the AD converter 9 and the waveform shaping circuit 1 .
The load and rotational speed of the engine are detected from the period of the fixed time pulse inputted from 0, the reference control signal corresponding to this operating state is read from the memory 12, and the control signal V _R5 shown in FIG. 5C is output.
Therefore, by inputting this control signal V _R5 , the phase shifter 3 changes the phase of the ignition pulse inputted from the waveform shaping circuit 2 shown in FIG. 5A by an angle θ ₂ over time as shown in FIG. 5D. outputs an ignition pulse whose phase is shifted to the delayed side. Therefore, the switch circuit 4 intermittents the power supply to the ignition coil 5 by inputting the ignition pulse whose phase is shifted by this angle θ ₂ , and the ignition voltage is generated at time t ₁₀ which is delayed from the reference time t ₉ , and the engine is activated. is driven. Here, even though the ignition was now delayed by an angle θ ₂ at time t ₁₀ ,
If the combustion state is slightly fluctuating and low-level knocks continue to occur, the knock signal K shown in FIG. 5B is output from the knock detector 7. Therefore, upon receiving this knock signal K, the arithmetic unit 11 outputs a control signal V _R6 obtained by adding a correction corresponding to this level to the control signal V _R5 . As a result, the next ignition is corrected by being performed at time t ₁₂ , which is delayed by an angle θ ₃ from the reference ignition timing t ₁₁ , and knocking is sufficiently suppressed. Therefore, angle θ ₃ is greater than angle θ ₂ ;
The difference between these, that is, the variation correction angle is (θ ₃ −
θ ₂ ), which corresponds to the level of the knocking signal K.

In this way, when the actual control amount greatly changes from the reference control signal read from the memory 12 by more than a predetermined value, by correcting the reference control signal value in the memory 12, it is possible to prevent a large change in the knocking state of the engine. , the reference control signal can be corrected, the above-mentioned seasonal change in the knocking occurrence factors can be corrected, and the reference control signal with an appropriate value can be stored.

Note that the initial value of the reference control signal in the memory 12 may be a value obtained from the engine setting value and may be stored in advance, or an average value thereof may be uniformly stored. Of course, the initial controllability can be improved compared to the case where it is set to zero. Furthermore, in the above embodiment, the output of the knock detector 7 is reset at each ignition timing.
Of course, the present invention is not limited to this, and may be performed only at the ignition timing after knocking occurs. It is also possible to add the detection signals and detect the amount of change when knocking occurs to carry out correction control. In this case, it goes without saying that it is only necessary to reset when the output reaches a predetermined value. On the other hand, there are many factors that cause knocking, and among these, air-fuel ratio control using ignition timing control or fuel control as shown in the embodiment is preferable. The reason for this is that many devices related to ignition timing control and air-fuel ratio control have been put into practical use, and are not only easy to implement, but can also be implemented at low cost. As an example of this air-fuel ratio control, it is of course possible to achieve the same function by increasing the amount of injection from the fuel injection device in accordance with a reference control signal corresponding to a knocking signal.

As explained in detail above, the knock suppression device for an internal combustion engine according to the present invention can promptly output and control an appropriate control signal when knocking occurs, and can also control the knocking when there is a change in the knocking generating factors. Appropriate knocking control can be performed by adding correction control corresponding to the number of minutes and performing sequential correction. Furthermore, by correcting the reference control signal value in the memory when the correction amount becomes larger than a predetermined value, it is possible to always perform appropriate knocking suppression in response to large fluctuations in the knocking generation factors. There is.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a knock suppressing device for an internal combustion engine according to the present invention, and FIG.
A diagram showing a reference control signal stored in the memory of FIG.
Figure 3A to Figure 3D, Figure 4A to Figure 4D, Figure 5
FIGS. A to 5D are diagrams showing waveforms at various parts in FIG. 1, respectively. 1...Ignition signal generator, 2...Waveform shaping circuit, 3...
Phase shifter, 4... Switch circuit, 5... Ignition coil, 6
... Acceleration sensor, 7... Knock detector, 8... Pressure sensor, 9... AD converter, 10... Waveform shaping circuit, 1
1...Arithmetic unit, 12...Memory. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An acceleration sensor that detects the vibration acceleration of an internal combustion engine and outputs a vibration signal; a means for removing a noise signal from the vibration signal from the acceleration sensor and outputting a knocking signal at a level corresponding to the knocking intensity; A detection means for detecting a load condition, a detection means for detecting a rotational speed of the internal combustion engine, and a reference control value for suppressing knocking is stored in correspondence with the load condition and the rotational speed, and is capable of being modified and memorized. determining a control signal for suppressing knocking from a storage means, the reference control value read from the storage means, and the knocking signal;
arithmetic means for outputting the control signal, and when the control signal exceeds the reference control value by a predetermined value or more, the value of the control signal is corrected and stored in the storage means as the reference control value. A knock suppression device for an internal combustion engine, characterized by: