JPH0220830B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a function to detect knocking by vibrations or sounds generated inside and outside the cylinder due to internal cylinder pressure of an internal combustion engine, and to retard the ignition timing when knocking is detected. The present invention relates to an ignition timing control device for an internal combustion engine. In recent years, various so-called knocking feedback systems have been studied that detect knocking occurring in internal combustion engines and retard ignition timing. The outline of the system is as follows. That is, it detects vibrations, sounds, etc. generated inside and outside the cylinder due to internal cylinder pressure of the internal combustion engine, and when these vibrations, sounds, etc. exceed a set level (knocking determination level), it is determined that knocking is occurring and a knocking signal is issued. When this knocking signal occurs, the ignition timing is retarded, and when the knocking signal does not occur, the ignition timing is advanced, thereby controlling the ignition timing always near the knocking limit and improving the fuel efficiency and output performance of the engine.

In this knocking feedback system, the amount of retardation when knocking is detected, that is, the amount of retardation per knocking, is predetermined and is usually about 1° CA. The amount of retardation per knocking is an important factor related to the controllability of ignition timing. In general, the smaller the retardation amount, the better the stability of the ignition timing, but conversely, the knocking noise, especially in a transient state such as during acceleration, becomes louder, and the driving performance in the transient state deteriorates significantly. On the other hand, if the amount of retardation is increased to a certain extent, driving performance in a transient state will be improved, but the ignition timing stability during steady driving will deteriorate, and therefore the driving performance during steady driving will deteriorate. In this way, the amount of retardation is determined to be a value that compromises both the steady state and the transient state, or it is determined by ignoring either one (normally, the performance during the transient state is ignored). Therefore, in the conventional system, the operating performance in either the steady state or the transient state is inevitably deteriorated.

The present invention has been made in view of the above problems, and includes a knocking detector that detects vibrations in the internal combustion engine body or the outside based on the knocking phenomenon of the internal combustion engine, and a knocking detector that detects vibrations in the internal combustion engine itself or the outside, and ignition according to the output signal from the knocking detector. An ignition timing control device for an internal combustion engine including an ignition timing control circuit that generates a timing signal and an ignition device that generates an ignition signal based on the ignition timing control signal from the ignition timing control circuit, wherein the ignition timing control circuit is configured to control the notching. Knocking determining means for determining the presence or absence of knocking in each combustion cycle according to the output signal of the detector, and retarding the ignition timing for each combustion cycle in which knocking occurs when the knocking determining means determines that the combustion cycle has knocking. and a retard amount increasing/decreasing means for increasing the retard amount by a set amount and decreasing the retard amount over time when a combustion cycle without knocking continues, and the retard amount increasing/decreasing means determines that there is knocking once by the knocking determining means. If the next cycle with knocking is determined before a predetermined number of cycles or a predetermined time have elapsed from the cycle in which it was determined that knocking has occurred, the set value for increasing the retard amount for each knocking is increased, An object of the present invention is to provide an ignition timing control device for an internal combustion engine, which includes a retard increase set value variable means for decreasing the set value or maintaining the set value at an initial set value when the cycle is not determined.

Under steady state conditions, when the ignition timing is controlled by the knocking feedback system, knocking occurs relatively infrequently, approximately once every 10 to 30 cycles. However, in a transient state such as during acceleration, knocks occur frequently at a frequency of about once every 1 to 3 cycles, so if a transient state is detected when such knocks occur frequently, a separate transient state detector is installed. The advantage is that it is not necessary.

FIG. 1 is a block diagram showing a first embodiment of the present invention. 1 is a knocking detector that detects the vibration or sound of the engine body corresponding to the engine knocking phenomenon using a piezoelectric element type (piezo element type), electromagnetic type (magnet, coil), etc.; 2 is the engine's basic ignition timing; 3 is an ignition timing control circuit that determines the actual ignition timing and generates an ignition timing control signal by receiving the signals from the knocking detector 1 and the distributor 2; It is an igniter that amplifies and normally shuts off an ignition coil (not shown). The configuration of the ignition timing control circuit 3 is as follows. 31 is a filter such as a band pass high pass for selecting and extracting only the knocking frequency component from the output of the knocking detector 1, and 32 is a knocking detection unit that receives the output signal from the filter 31 and detects whether or not the engine is in a knocking state. A circuit 33 receives a knocking signal generated by the knocking detection circuit 32, detects whether engine knocking occurs repeatedly within a predetermined period, and increases or decreases the amount of retardation per knocking based on the state of knocking occurrence. A variable delay amount circuit that maintains
Reference numeral 34 receives an output signal (retard amount signal) corresponding to the retard amount per knocking output from the retard amount variable circuit 33 and a knocking signal output from the knocking detection circuit 32, and retards the ignition timing from the basic ignition timing. 35 is a waveform shaping circuit for shaping the waveform of the pick-up signal from the distributor 2 and extracting the basic ignition timing;
Reference numeral 36 denotes an ignition timing calculation circuit that subtracts the retard amount output from the retard amount calculation circuit 34 from the basic ignition timing output from the waveform shaping circuit 35 to determine the actual ignition timing.

Next, using FIG. 2, the knocking detection circuit 32
The detailed configuration of is explained below. 321 is a half-wave rectifier for half-wave rectifying the output of the filter 31; 322 is a knocking detector 1 for integrating the output of the half-wave rectifier 321;
an integrator for extracting the average value of the vibration output of 3
23 is an amplifier for amplifying the output of the integrator 322 to create an appropriate knocking judgment level; 325;
324 is an offset voltage setter that shifts the voltage of the output of the amplifier 323 to obtain effects such as noise margin, and 324 is an offset voltage setter that adds the output of the amplifier 323 to the output of the offset voltage setter 325 to create the final knocking judgment level. adder, 32
6 compares the outputs of the half-wave rectifier 321 and the adder 324, and when the output of the half-wave rectifier 321 is larger, it is determined that knocking has occurred, and in that case, the comparator 327 compares the output voltage and generates knocking. Comparator 3
A trigger is generated at the output of 26, and the voltage signal is maintained for a certain period of time after the trigger, and is output once in each combustion cycle.
This is a monostable multivibrator that generates knocking pulses only once.

Next, the retard amount variable circuit 33 which is the main focus of the present invention
The detailed configuration and operation of the delay angle calculation circuit 34 will be described below with reference to the drawings. FIG. 3 shows the detailed configuration of the retard amount variable circuit 33 and the retard amount calculation circuit 34. In the figure, 331 is a counter that counts the knocking pulses output from the monostable multivibrator 327, 332 is a timer for resetting the count of the counter 331 at a predetermined time, and 333 is a counter that converts the digital value of the counter 331 into an analog voltage. D/ to convert to
The A converter 334 is a voltage-current converter for converting the voltage of the D/A converter 333 into current.
Next, 341 in the retard amount calculation circuit 34 is a switch 34 that closes only while the knocking pulse of the monostable multivibrator 327 is occurring and allows the current of the voltage-current converter 334 to flow only during that period.
2 is a capacitor for charging, 343 is a constant current source for discharging a constant current, and 344 is a capacitor 34
This is a buffer for taking out the second voltage.

The operation will be explained according to FIG. In the figure, a is a knocking pulse output from the monostable multivibrator 327 when knocking occurs. b is from the timer 332 to the counter 331
c is the output voltage of the D/A converter, and d is the output voltage of the buffer 344 representing the amount of retardation from the basic ignition timing. First, monostable multivibrator 3
When a knocking pulse is output from 27, the count number of counter 331 increases by 1, and at the same time, timer 332 is reset and starts counting time. If the next knocking pulse is output before the time counted by the timer 332 reaches the predetermined time, the count number of the counter 331 is further increased by 1, the timer 332 is also reset, and the time count is zero again. It starts from. In this way, if the next knocking occurs before a predetermined time has elapsed after the knocking has occurred, the count number of the counter 331 increases by one. If no knocking pulse is generated even after a predetermined period of time has elapsed, the timer 332 outputs a reset signal to reset the count of the counter 331 to zero (FIG. 3(b)). As a result, the first knocking pulse train shown in figure a (1 to 1 in figure a)
When the knocking pulses occur consecutively within a predetermined time as in 3), the count number of the counter 331 increases sequentially, and when the knocking pulses are output at intervals like the last knocking pulse (4 in a of the same figure), The count number increases only up to 1. This count state is represented by c in the figure.

The output voltage c of the D/A converter 333 is converted by a voltage-current converter 334 into a current proportional to this voltage. The voltage-current converter 334 is composed of two operational amplifiers 3341 and 3342, and the proportionality constant in voltage-current conversion is determined by each attached resistance value. For example, if each resistance value is set so that 1+R ₃ /R ₂ =R _f R ₅ /R ₂ R ₄ in Fig. 3, the voltage V and current I will be I = R _f R ₅ /R ₁ R ₃ Voltage-current is converted according to the relationship R ₄・V, and R ₁ = R _f = R ₄ = R ₅
If each resistor is set to satisfy the relationship, I=
A simple voltage-current conversion of V/R ₃ can be realized. Thus, the two operational amplifiers 3341 and 3
By using the counter 342, a current corresponding to the count number of the counter 331 is generated in a stable state. On the other hand, monostable multivibrator 32
When the knocking pulse is output from the switch 341, the switch 341 closes only while this notching pulse is rising, and during this period, a current corresponding to the number of counts of the notching pulse is passed from the voltage-current converter 334 through this switch. Flows into capacitor 342. Therefore, capacitor 342 is charged by this current, causing a voltage increase. Since the pulse width of the knocking pulse is fixed, the rise in voltage is proportional to the flowing current, and therefore the voltage rise is proportional to the number of counts of the knocking pulse. On the other hand, when no knocking pulse occurs, the switch 341 is open and the capacitor 342
The voltage that has been charged to is discharged through the constant current source 343 and decreases. In this way, by taking out the signal through the voltage buffer 344 of the capacitor, an output signal (FIG. 4d) corresponding to the amount of retardation of the basic ignition timing is obtained. The dotted line in FIG. 4d represents the retardation condition without the use of the present invention.
When using the present invention, for example, the amount of retardation for knocking pulse 1 (1 in Fig. 4a) is 1° CA,
The amount of retardation for knocking pulse 2 is 2°CA, and the amount of retardation for knocking pulse 3 is 3°CA.The more knocking occurs continuously, the more the retardation amount increases, so when accelerating, etc. In a transient state, the angle is quickly retarded, and subsequent occurrence of knocking can be kept to a minimum. In a steady state, knocking does not occur frequently, so the amount of retardation per knocking is kept small, so stable ignition timing control can be achieved, and appropriate ignition timing control can be achieved in both steady and transient situations.

In the embodiment described above, the continuation of knocking was determined temporally by the timer 332, but this can also be determined in a predetermined cycle. This second embodiment is shown in FIG. In this case, a counter 335 may be used instead of the timer 332. The operation will be explained with reference to the figure. .
The pickup signal output from the distributor 2 is waveform-shaped by a waveform shaping circuit 35 and inputted as a clock signal to a counter 335. The pickup signal of the distributor 2 is a basic ignition timing signal that is outputted prior to the combustion cycle of each cylinder to determine the basic ignition timing of each cylinder, so the counter 335 counts the output signal obtained by shaping the waveform of this signal. By doing this, you can know the progress of the number of cycles. By setting the constant of the counter 335 so that a reset signal is sent to the counter 331 at a predetermined number of cycles, it is possible to determine whether or not knocking continues at a predetermined number of cycles. The following operations are the same as those in the first embodiment, and will therefore be omitted.

In the first and second embodiments, if knocking is determined many times before a predetermined time or a predetermined number of cycles have elapsed, the amount of retardation per knocking is sequentially increased. It is also possible to maintain this increase in the amount of retardation at a predetermined amount of retardation. This is shown in FIG. 6 as a third embodiment.
In the figure, a Zener diode 336 functions to maintain a predetermined retardation amount. The operation will be explained below using FIG. In FIG. 7, a is the knocking pulse, and b is the timer 332 or counter 3.
35, c is the output voltage of the D/A converter without the Zener diode 336, d is the output voltage of the D/A converter with the Zener diode 336 included, and e is the basic ignition timing. This is the output voltage of the buffer 344 representing the amount of retardation from . If the Zener diode 336 is not present, and the knocking pulses shown in figure a are repeated 1, 2, and 3, the amount of retard angle per knocking will be, for example, 1° CA, 2° CA, as shown in figure c. It increases sequentially, such as 3°CA. At this time, if the Zener diode 336 is inserted and the Zener voltage is set to a voltage corresponding to 2° CA, the knocking pulse 3
Even if (3 in a of the same figure) occurs, the output voltage of the D/A converter corresponding to the amount of retardation per knocking is d in the same figure.
Therefore, the retard amount for the knocking pulse 3 remains at 2° CA.
In this way, the amount of retardation from the basic ignition timing becomes as shown in figure e, and compared to the case where the Zener diode 336 is not inserted (dotted line in figure e), the amount of retardation per knocking is maintained at 2° CA. Ru. By setting the Zener voltage of the Zener diode 336 to various values, the increase and hold pattern can be varied in various ways.

In the first to third embodiments, when the next knocking is not determined even after a predetermined number of cycles or a predetermined time has elapsed, the retard amount per knocking is returned to the initial state at once. It is also possible to sequentially decrease. This is shown in FIG. 8 as a fourth embodiment. This includes a U/D counter (up-down counter) 337 and an OR circuit 33 instead of the counter 331 in the first to third embodiments.
8. Monostable multivibrator 3391 and 33
92 is used. This operation will be explained using FIG. 9. In the figure, a shows the knocking pulse, and b shows the output signal of the timer 332. c is a countdown signal outputted from the OR circuit 338 to count down the U/D counter 337, d is the output signal of the D/A converter 333, and e is a buffer 344 representing the amount of retardation from the basic ignition timing.
is the output voltage of

The U/D counter 337 is counted up by the knocking pulse (FIG. 9a) output from the monostable 327, and at the same time, the timer 332 is reset and starts counting time. When the timer 332 counts for a predetermined time, it outputs a voltage to the monostable multivibrators 3391 and 3392 to decrease the count of the U/D counter. At this point, timer 332 is reset again and begins counting time again. If the knocking pulse is output before the timer 332 has counted the predetermined time, the timer 332 is reset and starts counting the time again from zero, in which case the timer 332 will not output an output signal. Become. The output from the timer 332 enters two monostable multivibrators 3391 and 3392, but the monostable multivibrator 3391 is triggered by the rising edge of the output signal of the timer 332, and the monostable multivibrator 3392 is triggered by the falling edge of the output signal of the timer 332. be. In this case, the monostable multivibrator 339
The pulse widths of 1 and 3392 are adjusted to be less than half the pulse width of the timer output signal. Monostable multivibrator 3391 and 33
The output signal of timer 332 is logically summed by OR circuit 338, and the output signal of timer 332 is decomposed into two pulses as shown in FIG. 9c. This OR
The output signal of the circuit 338 is inputted as a countdown signal to the U/D counter 337. When a knocking pulse as shown in FIG. 9a is generated, the output voltage of the D/A converter 333 becomes as shown in FIG. 9d, and the output voltage of the buffer 344, which represents the amount of retardation from the basic ignition timing, It becomes like e. In the figure e, the dotted line indicates the case where the retard amount per knocking is returned to the initial state at one time as in the first to third embodiments. By increasing or decreasing the amount of retardation per knocking as in the fourth embodiment, the transition between the transient state and the steady state becomes smoother, and the driving performance is further improved.

In the first to fourth embodiments, the counter 331, the D/A converter 333, the voltage-current converter 334, etc. are used as the elements of the variable delay amount circuit 33, but the same effect can be obtained even if other elements are used. This can be achieved. This is shown in FIG. 10 as a fifth embodiment.
In FIG. 10, 33A is a monostable multivibrator that is triggered by the falling edge of the knocking pulse output from the monostable multivibrator 327;
33B is an RS flip-flop, 33c and 33D are constant current sources, and 33E is a switch. The operation will be explained using FIG. FIG. 11a shows the knocking pulse outputted by the monostable 327, and b shows the output signal of the monostable multivibrator 33A triggered by the falling edge of the knocking pulse.
This output signal b is from the R-S flip-flop 33B.
The flip-flop 33B is input to the set side of the flip-flop 33B. As explained in the first to fourth embodiments,
The timer 332 outputs an output signal when a predetermined period of time has elapsed (see c in the same figure), and this output signal is sent to the flip-flop 3.
3B becomes a reset signal for flip-flop 33.
B becomes a falling state. d in the same figure shows the state change of the flip-flop 33B. When flip-flop 33B is in the "1" state, switch 3
3E closes, a knocking pulse is generated, and switch 3
41 closes, current flows into the capacitor 342 from the two constant current sources 33C and 33D, causing a large voltage rise. When flip-flop 33B is in the "0" state, switch 33E is open, so a knocking pulse is generated and switch 33E is open.
Even if the capacitor 41 is closed, the current flowing into the capacitor 342 is only from the constant current source 33D, and therefore the voltage rise of the capacitor 342 is small. In this way, the output voltage of the buffer 344, which represents the amount of retardation from the basic ignition timing, becomes as shown in Figure 11e. When knocking occurs repeatedly, the amount of retardation per knocking is large, and conversely, knocking does not occur much. Sometimes, the amount of retardation per knocking becomes small. The ratio between the large retard amount and the small retard amount is determined by the constant current source 33c.
and 33D can be freely changed by setting the constant current amount ratio to various values.

The present invention includes a knocking detector that detects vibrations in the internal combustion engine main body or the outside based on the knocking phenomenon of the internal combustion engine, an ignition timing control circuit that generates an ignition timing signal according to an output signal from the knocking detector, and an ignition timing control circuit that generates an ignition timing signal in accordance with an output signal from the knocking detector. An ignition timing control device for an internal combustion engine including an ignition device that generates an ignition signal based on an ignition timing control signal from an ignition timing control circuit, the ignition timing control circuit controlling each combustion cycle according to an output signal of the knocking detector. a knocking discriminating means for discriminating the presence or absence of knocking; and when the knotting discriminating means determines that the combustion cycle is a knotting combustion cycle, the ignition timing retard amount is increased by a set amount for each combustion cycle with knocking, and the combustion without knocking is performed. The retardation amount increasing/decreasing means decreases the retardation amount over time when the cycle continues, and the retardation amount increasing/decreasing means increases or decreases the retardation amount by a predetermined number of cycles or a predetermined time from the cycle once determined to be knocking by the knocking determination means. If it is determined that the next cycle with knocking has elapsed, the set value for increasing the retard amount for one knocking is increased, and if the cycle with knocking is not determined, the setting value is increased. Since the retard angle increase set value variable means is included to decrease or maintain the value at the initial set value, the amount of retard angle per knocking when knocking occurs can be varied by changing the length of the interval between knockings. This has the excellent effect of quickly suppressing transient knocking and suppressing fluctuations in ignition timing during steady state.

[Brief explanation of drawings]

FIG. 1 shows the first part of the ignition timing control device according to the present invention.
A block diagram showing an embodiment, FIG. 2 is an electric circuit diagram of the knocking detection circuit in FIG. 1, FIG. 3 is a detailed diagram of the retard amount variable circuit and retard amount calculation circuit in FIG. 1, and FIG. 4a -d are waveform diagrams for explaining the operation of the first embodiment, FIG. 5 is a partial block diagram showing the second embodiment of the device of the present invention, and FIG. 6 is a voltage-current conversion circuit in the third embodiment of the present invention. Detailed drawing of 7th
Figures a to e are waveform diagrams for explaining the operation of the third embodiment of the present invention, Figure 8 is a partial block diagram showing the fourth embodiment of the present invention, and Figures 9 a to e are the fourth embodiment of the present invention. 10 is a detailed diagram of the retard amount variable circuit and the retard amount calculation circuit in the fifth embodiment of the present invention, and FIGS. 11a to 11e are waveform diagrams for explaining the operation of the fifth embodiment of the present invention. FIG. 3 is a waveform diagram illustrating operation. 1...Knocking detector, 3...Ignition timing control circuit, 4...Ignition device.

Claims (1)

[Scope of Claims] 1. A knocking detector that detects vibrations in the internal combustion engine body or the outside based on the knocking phenomenon of the internal combustion engine, and an ignition timing control circuit that generates an ignition timing signal in response to the output signal from the knocking detector. and an ignition device that generates an ignition signal based on an ignition timing control signal from the ignition timing control circuit, wherein the ignition timing control circuit is configured to perform various activations according to the output signal of the knocking detector. Knocking discriminating means for discriminating the presence or absence of knocking in a combustion cycle; and when the knotting discriminating means determines that the combustion cycle is a combustion cycle with knocking, the amount of retardation of the ignition timing is increased by a set amount for each combustion cycle with knocking, and the knocking is detected. The retardation amount increasing/decreasing means decreases the retardation amount over time when a combustion cycle without knocking continues, and the retardation amount increasing/decreasing means increases the number of cycles or more from the cycle once determined as having knocking by the knocking determining means. If the next cycle with knocking is determined before a predetermined period of time has elapsed, the set value for increasing the retard amount for one knocking is increased, and if the next cycle with knocking is not determined. An ignition timing control device for an internal combustion engine, including a retard increase set value variable means for decreasing the set value or maintaining the set value at an initial set value. 2. If knocking is determined many times before the predetermined number of cycles or the predetermined time elapse, the amount of retardation per knocking is increased each time, and then the predetermined number of cycles or the predetermined time is determined. An internal combustion engine according to claim 1, characterized in that if the next knocking is not determined even after a predetermined period of time has elapsed, the amount of retardation per knocking is sequentially reduced or the retardation amount for each knocking is returned to the initial state at once. Ignition timing control device. 3. If knocking is determined many times before a predetermined number of cycles or a predetermined time elapse, the amount of retardation per knocking is increased each time, and the amount of retardation per knocking is increased each time. The ignition timing for an internal combustion engine according to claim 1, characterized in that when the retardation amount reaches a certain retardation amount, the ignition timing is maintained at a predetermined retardation amount per knocking even if the retardation amount reaches a predetermined retardation amount per knocking event. Control device.