JPH0114422B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ignition system for an internal combustion engine, and more particularly to an ignition system equipped with a control device that corrects ignition timing in accordance with the knock state of the engine. The knock that occurs in an internal combustion engine is closely related to the engine's ignition timing, and the earlier the engine ignition occurs before the top dead center of the piston, that is, at the advance position, the more likely the knock will occur, and the more likely the engine's ignition timing will be. It is known that engine torque can be maximized by setting the ignition timing to a position slightly retarded from the ignition timing at which knock occurs. For example, it is disclosed in Japanese Patent Application Laid-open No. 54-25334 and Japanese Patent Application Laid-Open No. 52-87537. Generally, the ignition timing that is set according to the engine speed and load is the standard ignition timing, and this standard ignition timing is set at the advance position where the knock occurs, and the knock is forcibly generated. Depending on the state of the knock, the ignition timing is retarded to a position closer to top dead center than the ignition timing when the knock occurred, and while the knock does not occur, the ignition timing is advanced from that retard position to the advanced position, and then the ignition timing is retarded. occurs, and the ignition timing is retarded in response to the knock, thus controlling the engine's ignition timing to the borderline ignition timing of whether or not a knock occurs. However, if you attempt to control the ignition timing by generating a knock as described above while the engine is rotating at high speed, the combustion temperature of the engine will rise abnormally, causing severe cylinder wear and extending the life of the engine. becomes shorter. SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional ignition system and to prevent an abnormal temperature rise in the engine when the engine rotates at high speed. A feature of the present invention is that when the engine speed rises above a predetermined value, the advance function that advances the ignition timing from the retard position to the advance position where the knock occurs is substantially stopped. be. Another feature of the present invention is that when the engine speed increases above a predetermined value, the ignition timing of the engine is retarded by a predetermined value from the knock occurrence boundary ignition timing. Another feature of the present invention is that when the engine speed rises above a predetermined value, the ignition timing of the engine is retarded by a predetermined value from the knock occurrence boundary ignition timing, and the ignition timing is advanced toward the knock occurrence region. This retardation amount is made larger than the amount of advance provided by the ignition timing means to substantially stop the advancement of the ignition timing. The present invention will be explained in detail below based on an embodiment shown in the drawings. FIG. 1 is a block diagram of an ignition timing control device using the present invention, FIG. 2 is a specific circuit diagram thereof, and FIGS. 3 is a drawing showing output waveforms of main parts. As shown in FIG.
and an ignition timing control section B for retarding the ignition timing from the reference ignition timing in accordance with the output of the knock detection section A. In FIG. 1, A1 is a knock sensor that converts engine vibration into an electrical signal. The knock-related vibrations included in engine vibrations have a unique frequency of 7 to 8 KHz. A2 is a band pass filter that passes only the electric signal corresponding to the vibration frequency of 7 to 8 KHz out of the output signal from the knock sensor A1, and the waveform of the output voltage _V01 is as shown in FIG. 5B. Figure 5A shows the primary current waveform of the ignition coil,
The point indicated by t ₀ is the point at which the primary current is cut off. Of the output voltage waveform V ₀₁ of the bandpass filter A ₂ , the waveform that appears from the primary current cutoff time t ₀ to the time t _a is the discharge of the spark plug riding on the electric wire connecting the sensor A ₁ and the bandpass filter A ₂ . This is due to noise. The waveform from time t _a to t _b is due to vibrations of the engine itself and is called background noise. The waveform from time t _b to _c is the signal waveform related to the engine knock, and the waveform from time t _c to the next primary current cutoff is the same as the background noise described above. Specifically, the bandpass filter _A2 includes resistors 1 to 9 and 11, and a capacitor 90, as shown in FIG.
~92, and operational amplifiers 191 and 192. This bandpass filter is a generally known two-stage active filter, but in order to be able to use it with one ground, the operational amplifiers 191 and 192 are
The reference terminal (positive terminal in the example) voltage is connected to resistor 3,
6 and resistors 5 and 7, it is fixed near the midpoint of the operating voltage (approximately 3V). The center frequency of the bandpass filter is f ₀ Hz, the gain at the midpoint frequency is H ₀ , and the ratio of the center frequency to the cutoff frequencies α ₁ and α ₂ above and below the center frequency
If f ₀ /α ₁ - α ₂ is Q, resistors 1, 2, 4, 8, 9 and 11 (respective values are R ₁ , R ₂ , R ₄ , R ₈ , R ₉ ,
R ₁₁ ), capacitors 91 and 92 (their values are C ₉₁ and C ₉₂ ) are given by the following equations. C _r = C ₂ (value is free) ...(1) R ₉ =K・R ₁ ……(3) Here ω ₀ =2πf ₀

[Formula]. In this example, from the experimental results, H ₀ = 10, Q = 20,
Since it was found that δ ₀ =7kHz was the easiest to distinguish the knock signal, the resistance value was selected using the above formula. _A3 is an amplifier that amplifies the signal that has passed through the bandpass filter by approximately 15 times. Specifically, the amplifier _A3 is an operational amplifier 193,
Transistor 131, diode 101, 10
2. Resistance 10, 12, 13, 14, 16, 17
(The respective resistance values are R ₁₀ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₆ , and R _17. ) _A4 is a sample and hold circuit that samples background noise, and _A5 is an attenuator that calculates the output of the amplifier. _A6 is a comparator that compares the knock signal that has passed through the attenuator with the sample signal from the sample and hold circuit. Sample and hold circuit _A4 , amplifier _A5 , comparator
_A6 is constructed as shown in FIG. That is, the configuration circuit including the resistor R ₁₀ , R ₁₂ diode 101, and transistor 151 is the operational amplifier 1.
This is a circuit for determining the DC operating levels V _B and V' _B of 93, and includes a diode 102 and resistors 16 and 17.
The configuration circuit is an attenuator that divides the output value of the operational amplifier 193 by resistor division. In Fig. 4, the voltage at the output point d of the operational amplifier 193 is V _p1 , and the voltage at the resistor-divided point e is V _p1 ', c
If the voltage at point is V _C , then the voltage at point c′ is V _C ,
The values of V _p1 and V _p1 ' are expressed by the following equations. V _p1 =R ₁ +R ₂ +R ₃ /R ₃・V _i −R ₁ +R ₂ /R ₃・V _c +V _f ……(6) V _p1 ′=R ₂ +R ₃ /R ₃・V _i −R ₂ /R ₃・V _c ……(7) Also, the voltage at the reference terminal g of the operational amplifier 192 is
Assuming V _g , the DC operating level V _B of V _p1 , V _p1 ′,
V _B ′ becomes as follows. V _B =R ₁ +R ₂ +R ₃ /R ₃・V _g −R ₁ +R ₂ /R ₃・V _c +V _f ……(8) V _B ′=R ₂ +R ₃ /R ₃・V _g −R ₂ /R ₃・V _c ……(9) The amplified vibration waveform V _p1 is the transistor 15
2, diode 103, and resistors 18, 19,
20 (=R ₁₉ , R ₂₀ ). The base of PNP transistor 152 is pulled by transistor 162 via resistor _R19 according to timing from a sampling time generator, which will be described later, and transistor 152 is turned on. Meanwhile, the vibration waveform V _p1 is the transistor 152, diode 1
However, due to the rectifying action of the diode 103, the maximum voltage of V _p1 during the sampling time is maintained in the capacitor 93. Here, the terminal voltage V _S of the capacitor 93 is the value obtained by subtracting the voltage drop V _f of the diode 103 from V _p1 , and the V _f term in equation (6) is eliminated, and V _S is the voltage drop of the diode 103. This value is not affected by temperature characteristics. The terminal voltage V _s of the capacitor 93 is maintained until the next spark occurs, but at the moment when the spark flashes, a transistor 161, which is a part of the mask time generator to be described later, is turned on, so that it is discharged through the resistor 20. Next, at the same time that the transistor 161 is turned off, the transistor 162 is turned on, and a new maximum voltage _Vs of _Vp1 is sampled and held in the capacitor 93. The operation from the amplifier output to sampling is shown in FIG. As a result of the experiment, the maximum time until point t _a where spark noise occurs is about 1.8 msec, and this period is considered as the discharge time of the sample voltage V _s of the capacitor 93.
It is appropriate to set the period up to t _a ′ as the sampling time. The sampling time is approximately
The highest value of the background noise of V _p1 is sampled at 0.7 msec. Subsequently, the operation of the comparator 194 will be explained with reference to FIGS. 4 and 5. The sample voltage V _s is connected to the terminal of the comparator 194, and the attenuated voltage V _p1 ′ of V _p1 is connected to the terminal, and V _s and V _p1 ′ are compared to obtain V _p1 ′.
If the knock signal is on, the sample voltage V _s
V _p1 ' becomes a higher voltage than that of comparator 1.
The output voltage V _p2 of 94 becomes High. This output state is shown in FIGS. 5c and 5D. In D, V _p2 is also between t0 and t _a ' on the time axis.
The level is set to High, and this process will be described later. The output voltage V _p1 of the amplifier is
The reason for lowering the value to V _p1 ′ is to provide a noise margin to avoid misidentification as a knock signal when noise is added to the signal waveform for some reason, and this is calculated using equation (6) ~
As is clear from (9), it can be set appropriately by changing the value of the resistor 17. A7 is a circuit that converts the knock amount into voltage.
Specifically, as shown in FIG.
5, diodes 104, 105, 106, resistor 2
3, 26 (=R ₂₃ , R ₂₆ ), capacitor 94 (C=
₉₄ ). The diode 106 is
It is a Zener diode of around 3V, and determines the voltage between the base of the PNP transistor 155 and the power supply _Vcc . On the other hand, a resistor is connected between the emitter of the PNP transistor 155 and _Vcc . Now, if the zener voltage of the diode 106 is V _Z106 and the voltage between B and E of the transistor 155 is V _B-E155 ,
The collector current I _C155 is a constant current as I _C155 ≒ V _Z106 −V _B-E155 /R ₂₃ ...(10). This constant current is determined by the output of the comparator 194.
When the output is high, it is charged to the capacitor C ₉₄ through the diode 105, and when the output is low, it is pulled through the diode 104 to the output transistor of the comparator. In this method, transistor 155
The negative influence of natural charging on the capacitor 94 due to leakage current can be prevented. Therefore, the terminal voltage V _C194 of the capacitor 94 is the sixth
As shown in the figure, if the rectangular wave width of the comparator 194 output is th, V _C194 = I _C155 · th/C ₉₄ (11), and the battery is linearly charged only when the output is High. Here, Fig. 5 C, D and Fig. 3 j, k, l
As shown in , when the knock amount is large, the signal is output for a long time.
Since the number of square waves increases, the amount of charge per knot increases. Therefore, if a method is adopted in which the delay angle from the reference ignition timing signal is controlled in proportion to the amount of charge in the capacitor 94, the optimum delay angle can be set depending on the size of the knock at that time. It is possible. A8 is a delayed signal generator, which will be specifically explained below. The delay signal generator used in this embodiment changes the knock amount to the voltage of the voltage converter, that is, the capacitor 94.
The terminal voltage of transistor 173, resistor 80,
51, which generates a delayed signal approximately proportional to the voltage of the converter. The delay signal is an angle signal based on the reference ignition timing signal from the ignition control circuit (specifically, the ON signal of transistor 173), and if the voltage of the converter is constant, the reference ignition timing is always at a constant angle. Generates a more delayed ignition timing signal. In the capacitor 97 in FIG. 2, charging and discharging are repeated by the bistable multivibrator in the delay signal generator to generate a triangular wave. The switching point from charging to discharging coincides with the reference ignition timing, and the discharging time is a delay time from the reference ignition timing. The switching point from discharging to charging occurs when the terminal voltage of the capacitor 97 reaches the reference voltage (in this example, approximately
1.5V). Now, assuming that the charging current is i ₁ and the discharging current is i ₂ , the discharging time Td is expressed as Td=T·i ₂ /i ₁ (12). T in equation (12) represents the time from the reference ignition timing signal to the next reference ignition timing signal. Therefore, converting equation (12) into angle Ad results in the following equation. Ad=Td/T×120°=i ₂ /i ₁ ×120°……(13) 120°……Crank angle between reference signals for 6 cylinders As is clear from equations (12) and (13) , the delay angle is
Directly proportional to i ₂ . Since this charging current i ₂ is determined by the resistor 51 connected to the emitter of the voltage follower transistor 173, the terminal voltage of the capacitor 94 and the delay angle are directly proportional. _A9 is a maximum voltage limiting circuit which limits the maximum value of the charging voltage of the capacitor 94, thereby making it possible to set the maximum value of the delay angle. Specifically, it is composed of diodes 107, 108 and a resistor 27 as shown in FIG. The leakage current of the Zener diode 108 causes the capacitor 94 to pass through the diode 107.
In order to prevent the charging voltage from spontaneously discharging, the Zener diode 108 is connected by the resistor 27.
is always biased to maintain a constant voltage. As a result, the highest voltage of the capacitor 94 is clamped, so in the method of setting the delay angle based on the charging voltage, it is possible to set the highest delay angle on the circuit. A ₁₀ is a noise mask time generator, and A ₁₁ is a sampling time generator, both of which are composed of a one-shot circuit. The operation will be explained with reference to the timing chart in FIG. 3 and FIG. 2. By interrupting the primary current of the ignition coil 201, an induced voltage as shown in FIG. 3b is generated at the collector of the power transistor 172. The pulse-like voltage that occurs immediately after the cutoff is due to the leakage inductance of the ignition coil and has a width of 10~
It is 20μsec and around 300V in height. In this embodiment, in order to use this as a trigger pulse for the one-shot circuit, resistors 74 and 75 are inserted in series between the collector of the power transistor 172 and the ground, and from the midpoint, by resistor division, approximately 1/5 of the collector voltage is
The voltage dropped to ~1/8 is connected to the Zener diode 131.
The voltage is applied to the base of transistor 158 via . The Zener diode 131 is for extracting only the peak wave of the induced voltage, and in the embodiment, a 27V diode is used. transistor 1
The diode 113 connected to the base of 58 is
This is to compensate for the E-B reverse breakdown voltage of the transistor 158 and to ensure the switching operation. Triggered by the peak voltage of power transistor 172, transistor 158
Turns on as shown in Figure c, and at the same time transistors 159 and 160 that have been turned on (in a stable state) until now
is turned off. In this OFF state, the electric charge stored in the capacitor 95 is reversely charged, and the points at the bases of the transistors 159 and 160 (Fig. 2 b, c
point) until it reaches the V _BE threshold.
Here, in this embodiment, one capacitor allows
In order to obtain two types of time, the resistors 34 and 35 are connected in series to form a reverse charging path for the capacitor 95, and from the dividing point to the base of the transistor 160 via the resistor 97, and the connection between the resistor 34 and the capacitor 95. The points are connected to the base of transistor 159, respectively. Therefore, the time for the base potential of transistor 160 to reach the threshold value of V _BE is shorter than that of transistor 159. The OFF time of transistor 159 is determined by resistors 34 and 35.
The OFF time of the transistor 160 is determined by the OFF time of the transistor 159 and the division ratio between the resistors 34 and 35. The operation of transistor 158 is in direct response to the operation of transistor 159 because its base is connected to the collector of transistor 159 via a resistor. On the other hand, transistor 1 that creates the shorter time
The base of a transistor 161 is connected to the collector of the transistor 60, and the transistor 161 outputs a phase-inverted waveform of the transistor 160. The collector voltage of the transistor 161 and the transistor 15 are connected to the base of the transistor 162.
9 collector voltage is resistor 39, diode 1
14 and 115 in an AND relationship, and the transistor 162 is turned on only from the time when the transistor 101 is turned off until the transistor 159 is turned on. The operations of the transistors 158 to 162 have been described in sequence from the time of sparking, and the waveforms in FIGS. 3a to 3g illustrate these operations. In the sample hold circuit described above, the collector of the transistor 162 is connected to the base of the transistor 152 through the resistor 19 and the diode 116, and the collector of the transistor 161 is connected to the capacitor 93 through the resistor 20, and when the transistor 161 is turned on, Therefore, while noise is being output from the amplifier, the previous noise level data held in the capacitor 93 is released, and the operation of sampling new noise level data by turning on the transistor 162 is as described above. This part functions as a sampling time generator. Also, between points t0 and t _a ' on the time axis in Figure 5, which will be described later in the explanation of the operation of the comparator,
Comparator 194 is at high level
The processing of the output voltage V _p2 in Figure 2 is as follows:
This is accomplished by connecting the collector of transistor 158 to the collector of transistor 155 via diode 120. As a result, timing chart c, h in Figure 3
As is clear from the waveform diagram, during the time when spark noise appears in the amplifier output, the collector current of the transistor 155 is drawn into the transistor 158 via the diode 120, so that charge is stored in the capacitor 94. There isn't. That is, the transistor 158 has the function of a noise mask time generator. Here, the collector of transistor 158 and resistor 3
The diode 112 inserted between 3 and 3 is
This is for temperature compensation of the threshold value of the base-emitter voltage _VBF of the transistors 159 and 160, thereby reducing temperature changes in sampling time and noise mask temperature. A ₁₂ is a voltage reduction circuit and transistor 156,1
57, a circuit consisting of diodes 109, 110, 111, and resistors 28, 29, 32, which reduces the voltage of the capacitor 94 in order to return the ignition timing, which has been delayed due to the generation of the knock signal, to the reference position. It is. The transistor 156 and the diode 109 are a constant current circuit using two adjacent IC transistors on one chip.
The current value is determined by a resistor 28 connected to the power supply. The collector of the transistor 157 is connected to the base of the transistor 156, and the base is connected to the transistor 161 which constitutes the above-mentioned sampling time generator via the diodes 110 and 111.
are connected to the collectors of transistors 1 and 1.
Transistor 157 only while 61 is ON
turns off, and the transistor 156 uses a constant current to draw out the charge from the capacitor 94 to which its collector is connected. As mentioned above, the transistor 161 is turned on for a certain period of time for each ignition, so the capacitor 9
The terminal voltage of No. 4 decreases by a constant voltage each time. Therefore, according to this system, the ignition timing delayed by the knock signal approaches the reference ignition timing by a fixed angle every time each ignition occurs. This method has the advantage of being able to control the ignition timing in accordance with the operating speed of the engine, compared to naturally discharging the capacitor 94 using a resistor. In other words, in the case of natural discharge, the time required to return to the reference ignition timing is constant, whereas in this system, the time required to return to the reference ignition timing varies in proportion to the engine speed, so it is possible to obtain good control characteristics. A ₁₂ is a minimum voltage limiting circuit, which limits the minimum voltage of the capacitor 94. Specifically, the lowest voltage limiting circuit is transistor 1.
53, diode 132, resistor 21, 24, 25
It is made up of. Resistors 21, 24, and 25 (=R ₂₁ , R ₂₄ , R ₂₅ ) are connected in series from the power source to the ground, and a diode 132 is inserted between the resistors 21 and 24. Since the base of the transistor 153 is connected to the connection point between the diode 132 and the resistor 21, the voltage drop V _f of the diode 132 and the base-emitter voltage V _BE of the transistor 153
The emitter is connected to the capacitor 94 in such a way that the . Therefore, since the transistor 153 forms a voltage follower circuit, the terminal voltage of the capacitor 93 is connected to the diode 132 and the resistor 2.
If the voltage is higher than the voltage at the connection point f with 4, it will not have any effect on the terminal voltage;
When the voltage tries to drop below the point voltage, the resistor 22 is removed from the power supply.
Since the transistor 153 causes current to flow through the capacitor 93, the lowest value of the terminal voltage of the capacitor 93 is always clamped to the potential at point f. During normal operation of the engine, transistor 165 is always
Since it is ON, the potential at point f is the Zener voltage V _Z112 of the Zener diode 112.
In this example, the potential is divided by 4.
It is set around 1.1V. The voltage V-f at point f is expressed by the following equation. V−f=(V _Z112 −V _f )・R ₂₄ /R ₂₄ +R ₂₄ ……(14) The reason why the minimum voltage limiting circuit is necessary is because the charging current of the delay signal generator mentioned above becomes too small and the delay angle This is to prevent the accuracy from deteriorating, and in this embodiment, it is set to a minimum of 5 μA or more. _A14 is a rotation speed detection circuit, which controls the operation of the voltage control circuit during high-speed operation, which will be described later. Specifically, as shown in FIG. 2, the rotation speed detection circuit includes resistors 40 to 50 and 60, 78, a comparator 195, transistors 163, 164, and diodes 117 to 122 and 122, 124, 1.
33 and a capacitor 96. The capacitor 96 includes a resistor 40 and a diode 11.
7 to the collector of the transistor 162, and when the transistor is ON as shown in FIG. 7f and g, the charge of the capacitor is discharged,
When OFF, resistor 41 (=R ₄₁ ) and capacitor 9
It is charged with a time constant of 6 (=C ₉₆ ). This charging voltage is used as a constant voltage source for the Zener diode 125 by resistors 42 and 43 (=R ₄₂ , R ₄₃ ).
When the reference voltage V _x obtained by dividing V _Z125 is exceeded, the output of the comparator 195 becomes High. If this reference voltage _V appears, and at higher rotations, only the Low signal is always available. Transistors 163, 164, resistors 45-4
9. The part formed by the diode 121 is a well-known bistable circuit, but if the signal that turns on the transistor 164 is used as a set signal, and the signal that turns it off is used as a reset signal, the set signal is generated by the diode 119. of transistor 161 connected directly to the base of transistor 163.
The ON signal and the reset signal are an AND signal of the output of the comparator 195 and the OFF signal of the transistor 159 connected by the diode 134. To explain this using the time chart in FIG. 7, regardless of other conditions, the transistor 161
is ON, the base current of the transistor 163 is drawn into the transistor 161 via the diode 119 and flows through the transistor 163.
is OFF, and transistor 164 is ON. Here, the influence that the voltage drop Vf ₁₁₉ of the diode 119 becomes higher than the base potential threshold of the transistor 163 and it cannot be turned off is that the transistor 1
It is removed by a diode 121 inserted between both emitter connection points of 63 and 164 and ground. This diode 121 also has a Schmitt effect when both transistors are switched on and off. On the other hand, the reset signal is an AND of the high signals of the comparator 195 and the transistor 159, so it is output at the same time as the set signal is output.
Since the set signal takes priority, there is no effect on circuit operation. When the set signal disappears, that is, when the transistor 161 switches from ON to OFF, the transistor 161 switches from OFF to ON, the capacitor 96 is discharged as described above, and the comparator output also switches to Low. Therefore, the set signal disappears almost at the same time as the set signal disappears, but the set time at this point is due to the delay in the operation of transistor 162 with respect to 161, and the resistance 117 which extracts the charge from capacitor 96.
Guaranteed by the time constant . That is, while the transistor 161 is on, the base current of the transistor 163 is drawn to the transistor 161 through the diode 119, so the transistor 163 is on and the transistor 164 is off. Next, when the transistor 160 is turned off, the output of the comparator is still high and at the same time, the transistor 159 is turned off, so the base current flows into the transistor 163, and the transistor 163 is turned on and the transistor 164 is turned off. 1
When 64 is turned off, the base current continues to be supplied by the resistor 47 connected from this collector to the base of transistor 163, so this state is maintained until the next set signal arrives. When the bistable circuit is reset, transistor 164 is in the OFF state. At this time, a resistor 44 connected to the collector of the transistor,
If only the resistor 49 connected to the power supply among the resistors 47, 49, and 50 is made smaller than the other resistors, the collector voltage can be made sufficiently high. If this voltage is set higher than the reference voltage (negative terminal) of the comparator 195 for rotation detection, which is set by the resistance division between the resistors 42 and 43, the influence on the reference voltage side will be increased by the diode 118. will disappear. On the other hand, when the bistable circuit is set, the transistor 164 is on, so current flows from the reference voltage side through the diode 118 and the resistor 44, and the resistors 43 and 44 are connected in parallel, lowering the reference voltage value. . Therefore, at low speed rotation, the reference voltage takes on a waveform as shown by the solid line in FIG. 7e, giving the comparator a Schmitt effect. Next, when the rotation becomes high speed and the comparator output is always at a low level as described above, the reset signal is no longer output and the transistor 163 is always OFF.
Transistor 164 is always turned on. For the above reasons, the transistor 164 operates in the same manner as the transistor 114 during low speed rotation, as shown by the solid line in FIG. 7i, and is always turned on during high speed rotation, as shown by the broken line in the same figure. _A14 is a high-speed operation voltage control circuit, which is a characteristic part of the present invention, and is turned on according to the output of the rotation speed detection circuit.
The transistor 165 has the function of fixing the voltage of the capacitor 94 to about 3V and obtaining the maximum amount of retardation. During high-speed operation, the movement of transistor 165 is
The shape is as shown by the broken line and hatching in FIG. V−f=V _Z112 −V _f )・(R ₂₄ +R ₂₅ )/R ₂₁ +R ₂₄ +R ₂₅
...(15) The voltage V-f shown by equation (15) is higher than that shown by equation (14) by _R25 ,
In the example, it is set to about 3V. At this time, if the terminal voltage of the capacitor 94 is operating at 3V or less, the transistor 153
The terminal voltage is suddenly raised to 3V, which is the same as V-f. When the capacitor 94 is operating at a terminal voltage of 3V or more, the transistor 164 is always turned on at a high speed, as shown by the broken line in FIG. 164, charging is stopped, and is gradually discharged by the transistor 156 of the voltage reduction circuit described above, settling down to 3V. Here, the movement of transistor 165 at high speed is
ON and OFF occur once each during one cycle of ignition, and the voltage at point f is alternately expressed as approximately 1V and approximately 3V as expressed by equations (14) and (15), but as mentioned above, Transistor 1 during one period as
Since the voltage of the capacitor 94 lowered by 56 is a value of around 0.1 degree when converted into an angle,
Its terminal voltage is clamped at the higher potential of 3V. Therefore, at high speed (4000 rpm or more in the example),
Since ignition is always delayed by a certain angle (10 degrees in the example) from the reference ignition timing determined by the rotation speed and load, the ignition is always delayed slightly from the knock zone, that is, slightly retarded from the boundary ignition timing. ignition is done. Furthermore, as mentioned above, since the transistor 164 is always in the ON state at high speed, the transistor 164
The collector of capacitor 55 is grounded through diode 122, and even if a knock signal appears on comparator 194, capacitor 94 is not charged, and the voltage of capacitor 94 is controlled to the above-mentioned 3V. Furthermore, in the embodiment, the minimum voltage of the capacitor 94 is
The base current of the transistor 165, which is switched in response to high-speed operation and low-speed operation, is generated by a resistor 77 connected to the collector of the transistor 160, a resistor 124 connected to the collector of the transistor 164 via a diode 124, and a rotation detector. It is supplied by four resistors: resistor 78 connected to the output of comparator 195, and resistor 62 connected to the collector of transistor 167 in the ignition control circuit. As shown in FIG. 7, the operation of the transistor 160 is opposite in phase to that of the transistor 161, and therefore, the phase is also opposite to that of the transistor 164 during low speed rotation. Therefore, when the transistor 160 is ON, the transistor 164 supplies the base current of the transistor 165 through the resistor 56, and when the transistor 164 is ON, the transistor 160 supplies the base current of the transistor 165 through the resistor 77. It's on. On the other hand, during high-speed rotation, the transistor 164 is always
Since the transistor 165 is in the ON state, the transistor 165 is ON only when the transistor 160 is OFF. The moment the ignition key 204 is turned on, the transistor 160 turns on, and the capacitor 96 begins to be charged through the resistor 41. During the time td until the terminal voltage of the capacitor 96 reaches the reference voltage of the comparator 195, the output of the comparator is at a low level, so the transistor 164 is in the ON state during this period. Therefore, the base current of transistor 165 is
Since the transistor 165 is not supplied from either collector of 0 or 164, and the transistor 165 is turned off during time td, the voltage of the capacitor rises to the voltage required for delaying at high speed, and the ignition timing is delayed from the normal ignition timing at the time of starting. At that point, the phenomenon of ignition occurs. Engine startability may or may not be better if the ignition timing is delayed from the normal timing.For the former, it is better to leave it as it is, but for the latter, Therefore, it is necessary to take measures against this. Resistors 60 and 78 were added as a countermeasure to this problem. That is, the resistor 60 causes the ignition key 204 to
A high signal is output the moment it is turned on, and at high speed, it cannot prevent the transistor 165 from turning on and off. In this embodiment, it is connected to the collector of the transistor 167 in the ignition timing control circuit.
Transistor 165 is turned on at the same time as the ignition key is turned on. Also, the transistor 164 is activated even during low speed rotation.
There is a time when it is ON, but this time is within the noise mask time, so there is no adverse effect on the operation of converting the knock amount to voltage. However, when I turned the starter for starting, voltage was generated in the pick-up coil 207, and until now it was ON.
Since the transistor 166 that was in operation is turned off, the transistor 167 in the next stage is turned on, and there is a time when the base current of the transistor 165 is not supplied and the transistor 165 is turned off. What makes up for this time is
Resistor 78 connected to the output of comparator 195
It is. In other words, from the moment the ignition key 204 is turned on until the capacitor 96 is charged, the current from the transistor 167 operates the transistor 165.
After the capacitor is charged and the output of the comparator 195 becomes High, the current from the output of the comparator 195 is used to connect the transistor 16.
5 is always turned ON when starting. This also makes it possible to prevent the ignition timing from being delayed from the normal timing at the time of starting. Depending on the engine's requirements, it can be arbitrarily selected whether or not to delay the start. B ₁ is a reference ignition position signal generator, B ₂ is an ignition control circuit, B ₃ is an amplifier, and B ₄ is an ignition coil, which will be specifically explained based on FIG. 2. Positive and negative alternating current waveforms as shown in FIG. 3m appear in the pickup coil 203 in synchronization with the rotation of the engine. Transistor 166 is normally biased and turned on by resistor 82, but
The voltage generated by the pick-up coil 203 causes the second
When point y in the figure becomes negative, it turns OFF, so transistor 167, which had been OFF until now, turns ON, and in the same way, transistor 173 turns OFF, transistor 168 turns ON, and transistor 16
9 and 170 are turned off, the power transistor 172 is turned on, and the primary current of the second ignition coil 201 flows. Next, when the y point changes relatively sharply from negative to positive, transistor 166 turns on, and the following 16
7 is OFF and 173 is ON. The ON signal of this transistor 173 is sent to the delay signal generator as a reference ignition timing signal. of transistor 173
When turned on, the transistor 168 is turned off, or the delayed signal from the delayed signal generator is sent to the base of the transistor 169 at low level.
The ON of 169 is delayed from the reference position signal by the amount of the delay signal. Hereinafter, this delay is caused by the transistor 170
is turned ON and the power transistor 172 is turned OFF, and the interruption of the primary current 201 of the ignition coil 201 is delayed by the delay signal. In other words, the ignition timing is delayed. Transistor 171 is for limiting the maximum value of the primary current. As explained above, according to the present invention, no knock occurs when the engine speed exceeds a predetermined speed, that is, when the engine rotates at high speed, and the combustion temperature of the engine does not rise more than necessary. can be prevented and the life of the engine can be extended.

[Brief explanation of drawings]

FIG. 1 is a block diagram explaining an embodiment of the present invention, FIG. 2 is a circuit diagram of an embodiment of the present invention, and FIG. 3 a
〜m is a timing chart diagram, FIG. 4 is a detailed explanatory diagram of the sample hold circuit and comparator, and FIG. 5A~
D is an explanatory diagram of the operation of the same circuit, Figs. 6 D' and E are explanatory diagrams of the operation of the knock amount → voltage conversion circuit, and Figs. 7 a to k.
is the timing chart of the rotation detection section, Fig. 8a,
b is a diagram showing the characteristics of an embodiment according to the present invention in principle.

Claims (1)

[Claims] 1. A first means for detecting engine vibration and converting it into an electrical signal, a second means for discriminating an electrical signal associated with an engine knock from the output of the first means, and a method according to the output of the second means. a third means for forming a signal related to the knock; a fourth means for determining a retard amount in accordance with the output of the third means; and a fifth means for advancing the ignition timing; In the fifth means, the ignition timing of the engine is controlled to the knock occurrence boundary ignition timing, wherein the sixth means generates an output upon detecting that the number of rotations of the engine becomes equal to or higher than a predetermined number of rotations; seventh means operated by the output of the sixth means to retard the ignition timing of the engine by a predetermined amount from the knock occurrence boundary ignition timing; An ignition timing control device for an internal combustion engine, characterized in that the retard amount by the seventh means is set larger.