JPS6157949B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition timing control device for preventing premature ignition of a spark internal combustion engine.

[Prior art] In a spark engine, when the temperature of a spark plug or the like rises abnormally, it becomes a hot spot, and the hot spot ignites the air-fuel mixture before the spark discharge ignites it, which is similar to advancing the ignition timing. The result is
As a result, the temperature of the hot spot further increases, advancing the ignition timing, which is known to cause engine troubles such as knocking.

[Problems to be Solved by the Invention] The present invention detects ignition caused by a hot spot that is not controlled by such spark discharge, and delays the ignition timing by a predetermined period to lower the temperature of the hot spot and prevent engine trouble in advance. The purpose of this invention is to provide an ignition timing control device for an internal combustion engine.

[Means for Solving the Problems] In order to achieve the above object, the present invention delays the spark discharge timing by a certain time t ₁ at predetermined intervals, and causes the ion current due to hot spot ignition to flow into the ignition circuit within the delay time t ₁ . A configuration is adopted in which the presence or absence of hot spot ignition is determined by detecting whether or not the ion current has occurred, and the ignition timing is delayed for a predetermined period when the ion current is generated.

[Example] The present invention will be explained based on embodiments shown in the drawings.

V is a battery installed in the internal combustion engine ignition circuit,
C ₀ is the ignition coil, B ₀ is the interrupter, P is the ignition plug, 1
00 is an ignition timing control device according to the present invention.
1 is an unstable multivibrator that outputs sampling pulses shown in FIG. 3A at regular intervals;
For example, pulses are output at intervals of once per second. 2 is the above sampling pulse and Fig. 3B
Input the opening/closing pulse of interrupter _B0 shown in Figure 3C.
This is a bistable multivibrator that generates the engine rotation detection pulse shown in , and detects the opening of the first interrupter B ₀ when the sampling pulse is input. 3 is a certain period of time (for example, 100 microseconds to 200 microseconds) from the start of spark discharge (when the interrupter changes from ON to OFF)
This is a monostable multivibrator that outputs the spark discharge timing delay pulse shown in FIG. 3D. The width of this spark discharge timing delay pulse is determined as follows. Normal ignition takes place with a delay of, say, 200 microseconds after the spark discharge, and this is called the ignition delay time, but the ignition delay time is almost unaffected by changes in the ignition timing, and if the ignition is delayed by 210 microseconds, the ignition time will also be different from the normal ignition time. Delayed by 210 microseconds.
In other words, the timing of ignition and combustion is controlled by spark discharge. However, if a spark plug or the like becomes a hot spot and ignition is done by the hot spot and is no longer controlled by spark discharge, the ignition timing will not be delayed in accordance with the delay in the spark discharge timing, but will ignite within the delay time of the spark discharge timing. It becomes like this. Therefore, by setting the delay time of the spark discharge timing to be somewhat larger (e.g., 210 microseconds) than the normal ignition delay time (e.g., 200 microseconds), premature ignition caused by a hot spot can be prevented by the ignition circuit. It can be detected from an early stage by the ionic current generated in the process. Therefore, it is desirable that the width of the spark discharge timing delay pulse be determined somewhat larger than the normal ignition delay time. 4 is a monostable multivibrator which inputs the opening/closing signal of interrupter B ₀ and outputs a pulse having a width t ₁ for setting the ignition advance delay time t ₁ shown in FIG. 3E; 5 is the monostable multivibrator; As shown in FIG. 3F, the outputs of the stable multivibrators 3 and ₄ are input. As shown in FIG. This is an AND circuit that produces an output that gives a time corresponding to . 6 is a voltage comparison circuit for detecting the ionic current accompanying ignition when ignition occurs in the engine, and is connected in series between the secondary side of the ignition coil and the ground, as shown in Figure 2. and resistance at connection point b
A resistor _R1 that applies a voltage of the same polarity as the high voltage applied to the spark plug via _R1 , a power supply _V1 , a diode _D1 connected in parallel to the resistor _R1 , a capacitor _C1 , and the capacitor _C1. Voltage dividing resistors R ₂ and R ₃ inserted between the ground and resistor R ₄ that divides the power supply voltage Vcc,
It consists of _R5 and a comparator 61 which inputs the divided voltages of these voltage dividing circuits. In this voltage comparison circuit 6, when the center electrode side and the ground side of the spark plug are electrically connected due to the ionic current generated by ignition, a voltage drop occurs across the resistor _R1 due to the power supply _V1 , and when the potential of the b terminal changes, Capacitor C ₁ is discharged via resistor R ₃ and resistor R ₂ , current flows, and voltage is generated across resistor R ₂ and resistor R ₃ . When the input voltage of the comparator 61 set by the resistor R ₂ and the resistor R ₃ becomes larger than the input voltage of the comparator 61 set by the resistor R ₄ and the resistor R ₅ , the third
As shown in Figure G, a pulse with a width corresponding to the ignition time is output. Reference numeral 8 inputs the output of the voltage comparison circuit 6 and the output pulse of the AND circuit 5, and detects the time span _t3 from the generation of the ionic current to the spark discharge within the set spark discharge timing delay time _t1 . Figure 3 I
9 is a pulse width amplification circuit that amplifies the output pulse _{p 1} of the AND circuit 8, and as illustrated in FIG. 4, transistors T ₁ , T ₂ , resistors R ₆ to R ₁₀ , diode D ₃ , and capacitor C _{2 ,} and outputs a pulse P ₁ that sets the amplified ignition advance delay period T ₃ shown in FIG. 3J. 11 is an AND circuit,
Input the pulse P ₁ and the output of the monostable multivibrator 4, and set the delay period as shown in Figure 3L.
A retard signal pulse p ₂ corresponding to the delay time t ₁ occurring during T ₃ is output. Reference numeral 12 denotes a retard control circuit which inputs the output of the amplifying circuit 9 and retards the ignition advance.As shown in FIG. 5, the base is connected to the output terminal of the amplifying circuit 9, and the collector is connected to the The emitter is connected to the ignition coil contact (point B in the figure) of the ignition coil of the device _B0 , and the emitter is made up of a grounded power transistor T and a Zener diode Zr connected in parallel. The output pulse shown is input to the base of the transistor, and the ignition coil side of the interrupter B ₀ and the ground side are electrically connected.
The operation of the interrupter is delayed, the spark discharge is delayed, and the ignition advance is retarded by the ignition delay time _t1 .

In this embodiment, the periodic spark discharge timing delay circuit includes the above-mentioned unstable multivibrator 1, bistable multivibrator 2, monostable multivibrator 3, 4, and AND circuit 5, and has a delay interval t ₀
and a setting circuit 200 that sets the delay time _t1 ,
It is comprised of a retard control circuit 12 that grounds the input terminal of the interrupter B ₀ according to the input time and delays the output of the OFF signal of the interrupter by t ₁ time. Also,
The voltage comparison circuit for detecting the ion current includes the setting circuit 200, the ion current detection circuit 6, and the AND circuit 8, and when the ion current is detected within the delay time _t1 , ignition occurs due to a hot spot. Then, it outputs a pulse p ₁ corresponding to the time t ₃ from the generation of the ionic current to the spark discharge. This pulse p ₁ is amplified by the amplification circuit 9 to produce a pulse P ₁ having a time width that sets the ignition timing delay period T ₃ . All spark discharges occurring within this delay period T ₃ are delayed by the delay time t ₁ . This delay period T ₃ corresponds to the time width t ₃ from the generation of the ionic current caused by the hot spot ignition to the spark discharge by the spark plug P within the delay time t ₁ . The ignition timing delay period _T3 increases or decreases depending on whether the ignition timing occurs early or late. Note that the number of spark discharges performed within this delay period _T3 varies depending on the rotational speed of the engine.

As a result, the spark discharge is delayed by the time t ₁ set by the pulse p ₂ during the delay period T ₃ as shown in FIG.

[Effects of the Invention] As described above, the ignition timing adjustment device of the present invention delays the spark discharge timing, detects the presence or absence of ion current due to hot spot ignition within the delay time _t1 , and detects whether hot spot ignition occurs. When this happens, the ignition advance is delayed for a predetermined period of time, so the temperature of the hot spot can be lowered. This makes it possible to reliably prevent the progression of pre-ignition and prevent engine troubles such as knotting in advance. Further, since the ignition timing delay period T ₃ is changed according to the ion current generation time t ₃ due to thermal ignition within the ignition timing delay time t ₁ , it is possible to always maintain normal engine rotation.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the ignition timing control device of the present invention, Fig. 2 is a circuit diagram of a voltage comparison circuit, and Fig. 3 is a diagram of A, B, C, D, E, F, G, I, J, L, M is a waveform diagram for explaining the operation, FIG. 4 is a circuit diagram of the pulse amplification circuit, and FIG. 5 is a circuit diagram of the retard control circuit. In the figure, 1...unstable multivibrator, 2...
... Bistable multivibrator, 3, 4 ... Monostable multivibrator, 6 ... Voltage comparison circuit, 5,
8, 11...AND circuit, 12...Retard angle control circuit, _B0 ...Interrupter, _C0 ...Ignition coil, P...
Spark plug.

Claims (1)

[Scope of Claims] 1. A periodic spark discharge timing delay circuit that delays the spark discharge timing by a predetermined time _t1 at a predetermined period; and a voltage comparison circuit that detects an ionic current generated in the ignition circuit within the delay time. An ignition timing control device for an internal combustion engine, comprising: a retard control circuit which receives the output of the voltage comparison circuit as an input and delays the spark discharge timing by a predetermined period _T3 when an ionic current is generated. 2. The retard control circuit sets a period _T3 for delaying the spark discharge timing according to a generation time _t3 of the ion current generated within the delay time _t1 . The ignition timing control device for an internal combustion engine according to item 1. 3. Ignition timing control for an internal combustion engine according to claim 1, wherein the delay time _t1 of the spark discharge timing is set to be somewhat larger than the ignition delay time from spark discharge to ignition under normal conditions. Device.