JPS6252146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current interrupt type non-contact ignition device for an internal combustion engine.

A circuit as shown in FIG. 1 has been provided as a conventional current interrupt type non-contact ignition device of this type. This consists of a trigger circuit A that supplies a trigger voltage, a switching control circuit B that receives the trigger voltage and interrupts a primary short-circuit current, a protection circuit C for electronic components, an ignition coil D, and a spark plug E. The trigger circuit A, switching control circuit B and electronic component protection circuit C are connected to lines l ₁ and l ₂ at both ends of the primary coil of the ignition coil D.
That is, in trigger circuit A, a series circuit consisting of resistors 1 and 2 and a capacitor 3 and a series circuit consisting of resistors 4 and 5 are connected in parallel between l ₁ and l ₂ . A programmable union transistor (hereinafter referred to as PUT) 6 is connected between the connection midpoint of the resistors 1 and ₂ and the line l2.
A series circuit consisting of a resistor 7 and a resistor 7 is connected, and this
The gate of PUT6 is connected to the midpoint between the resistors 4 and 5.

In the above switching control circuit B, the line
A resistor 8 and the collector-emitter of a switching transistor 9 are connected in series between l ₁ and l ₂ , and the base of the switching transistor 9 is
Connected to the midpoint between PUT6 and resistor 7. Reference numeral 10 denotes a primary short-circuit current interrupting transistor whose collector and emitter are respectively connected to lines l ₁ and l ₂ , and whose base is connected to the midpoint between the resistor 8 and the collector of the switching transistor 9 .

The protection circuit C for electronic components includes a diode 11 and a resistor 12 connected in series between the lines _l1 and _l2 , and bypasses the negative current of the primary short-circuit current so that it does not burden the electronic components, especially the transistor 10. It is.

In such a current interrupt type non-contact ignition device, the voltage induced in the primary coil 13a of the ignition coil D when the engine starts is applied between the lines _l1 and _l2 , and the current _I0 is applied to each branch circuit. ₁ , I ₂ , I ₃ , and I ₄ . Further, the operating current of the PUT 6 is determined by the potential at the midpoint of the connection between the resistors 1 and 2 and the potential at the midpoint of the connection between the resistors 4 and 5. The magnitudes of the currents I ₃ and I ₄ are set so that they turn on at the peak of the primary short-circuit current or at a position slightly past the peak. When PUT6 is turned on in this way, the base of switching transistor 9
Since current flows between the emitters, this switching transistor 9 is turned on, and transistor 1
0 is off. Therefore, the primary short-circuit current is abruptly cut off, a maximum level of high voltage is generated in the secondary coil 13b of the ignition coil D, and a spark is generated in the spark plug E. In this way, the mixture is combusted and the engine is driven.

However, in a non-contact ignition system having such a configuration, when the engine speed is gradually increased after starting the engine, the primary short-circuit current passing through the transistor 10 reaches a peak or a position slightly past the peak.
PUT 6 was turned on, but due to the charging and discharging time constants of resistors 1 and 2 and capacitor 3, the on operation timing is gradually delayed, and therefore the timing of cutting off the primary short circuit current is also delayed, and the engine ignition timing is delayed. As shown in Figure 2, there was a delay. Q ₀ in the diagram
is the appropriate ignition timing for the engine (the same applies below). Therefore, as shown in Figure 2, if the proper ignition timing for the engine is obtained during normal rotation, the ignition timing will be approximately at the proper ignition timing for normal rotation even at startup, so the piston will not reach top dead center. There was a problem in that the engine was forced to descend before it reached the desired position, that is, the engine's rotation was physically reversed by a large amount of force, resulting in poor starting performance. On the other hand, the above resistance 1,
By appropriately selecting the charging time constants of capacitor 2 and capacitor 3, the operation timing of PUT 6 can be advanced, but in this case, although the starting performance is improved, proper ignition timing cannot be obtained during normal rotation. However, there were problems in that fuel efficiency deteriorated and engine output decreased.

Therefore, the inventor improved the startability of the engine and advanced the ignition timing until it reached the normal rotational speed range after startup and then set it roughly (appropriate ignition timing of the engine).
We devised a non-contact ignition system that can stabilize the engine output by adjusting the engine output.

FIG. 4 is a circuit diagram showing such a non-contact ignition device, and the difference between this and the one shown in FIG. 1 is that when the positive induced voltage of the primary coil 13a of the ignition coil D reaches a set value, an advance angle circuit F that has a Zener diode 14 that breaks over, and supplies a trigger voltage to the switching control circuit B with priority over the trigger circuit A when the Zener diode 14 breaks over;
This is because we have established the following. i.e. above line l ₁
An advance angle circuit F consisting of a series circuit of a Zener diode 14 and a resistor 15 is connected between the switching transistor 9 and the base of the switching transistor 9. Further, a diode 16 is connected between the emitter of the transistor 10 and the primary coil 13a in the direction shown.

In this circuit, as described above, when the engine is started, PUT 6 is turned on at or slightly past the peak of the primary short-circuit current, thereby turning on switching transistor 9, and then turning on transistor 10. is turned off, the primary short-circuit current flowing through this transistor 10 is cut off, and a high voltage is generated in the secondary coil 13b of the ignition coil D.

Next, as the engine speed gradually increases, the charging/discharging time constant of the circuit consisting of resistors 1 and 2 and capacitor 3 causes PUT 6 to reach the peak or slightly past the peak of the primary short-circuit current. It turns on at the same position, but the timing at which it turns on gradually becomes delayed. For example, it looks like the solid line X or the dotted line Y in FIG. The solid line X shows the case where the charging time constants of the resistors 1 and 2 and the capacitor 3 are set relatively large, and the dotted line Y shows the case where the charging time constants are set relatively small.

Furthermore, as the engine speed increases, line l ₁
The potential reaches the set potential of the Zener diode 14 and breaks over. For this reason, until now, the two transistors 9 and 10 were controlled to be turned on and off by turning on the PUT 6, but the Zener diode 14, the resistor 15,
By sensing the voltage level of the voltage dividing circuit 7, the on/off control of the two transistors 9 and 10 is preferentially controlled by the series circuit of the Zener diode 14 and the resistor 15, and the voltage dividing circuit of the resistor 7. It will be controlled. Therefore, from the time the engine was started until the Zener diode 14 broke over, the operation of the PUT 6 was delayed due to the above charge/discharge time constant, but when the Zener diode 14 broke over, Therefore, the on/off operations of the transistors 9 and 10 proceed gradually or rapidly. For example, the solid line X in Figure 3
Or it will look like the dotted line Y. The solid line X indicates the case where a Zener diode 14 with a relatively high Zener voltage is used, and the dotted line Y indicates the case where a Zener diode 14 with a relatively low Zener voltage is used. For this reason, the engine's ignition timing is gradually delayed when the rotational speed of the Zener diode 14 is on the verge of breakover, and when the rotational speed further increases and the Zener diode 14 breaks over, the engine's ignition timing is gradually advanced or spark-advanced. .

Therefore, when the engine speed is increased, the ignition timing remains approximately constant (appropriate engine ignition timing) in the low speed (clutch-in rotation), medium speed, and normal speed ranges. . Especially in the case of Figure 4,
By the diode 16, the ignition coil D
The negative current of the primary coil 13a of the transistor 1
0 (emitter collector), so there is no effect of armature reaction, so a primary short-circuit current (positive current) that does not cause a delay flows through the transistor 10, and it can be used at low or medium speeds. The deviation from the proper ignition timing is extremely small in each rotation range of the normal rotation speed.

As described above, the non-contact ignition device shown in FIG. 4 improves the startability of the engine, ensures proper output of the engine, and improves fuel efficiency. Note that the resistor 5 is replaced by resistors 17 and 18 and a thermistor 19 as shown in FIG.
By replacing the PUT 6 with a temperature compensation circuit consisting of the following, temperature compensation of the PUT becomes possible.

FIG. 6 is a modification of the circuit shown in FIG. 4 above, and similarly to FIG. 4, it shows a circuit devised by the inventor in carrying out the present invention. A protection circuit for ignition coil D is connected. This protection circuit G consists of a resistor 20 and a thyristor 21 connected in series between lines _l1 and _l2 , and two resistors 22 and 23 connected in series between the midpoint of these connections and line _l2 , The gate of the thyristor 21 is connected to the midpoint between these two resistors 22 and 23.

In the circuit shown in the fourth diagram above, the engine speed is low, medium speed,
In the normal rotation speed range, the influence of armature reaction does not occur as described above, so as the surge voltage as the primary cut-off voltage increases, it may cause dielectric breakdown or insulation deterioration of the transistor 10 and especially the ignition coil D. may be invited. However, in the circuit shown in Figure 6, when the ignition coil D is in a no-load state,
By detecting the voltage level at the midpoint of the connection between the resistors 22 and 23 and turning on the thyristor 21, the voltage applied to the ignition coil D is shunted to a set level, and the primary cutoff to the ignition coil D is performed. Cuts the excess voltage (surge voltage) and secondary no-load voltage, and removes the spark plug E.
can be set to the value necessary to generate a spark. By varying the values of the resistors 22 and 23, the primary cutoff voltage (surge voltage) can be adjusted freely.
and the value of the secondary no-load voltage can be set.

In addition, the thyristor 21 and the resistors 20, 22, 2
It is also possible to protect the above-mentioned electronic components and ignition coil by connecting a varistor of a surge absorption element between the _l1 line and the _l2 line instead of 3.

However, with the non-contact ignition systems shown in Figures 4 and 6 above, the ignition timing during high-speed rotation of the engine is maintained at the proper ignition timing of the engine in the same way as in the normal rotation range, resulting in good fuel efficiency and engine output. This often results in over-rotation and seizure of the crankshaft, and accidents such as the flywheel rotor falling off or flying off, leading to problems such as reduced durability and personal injury.

The present invention solves the above-mentioned problems, and is capable of retarding the ignition timing when starting the engine, improving starting performance, and advancing the ignition timing to the proper ignition timing of the engine at low speeds (before idling). to maintain the above-mentioned appropriate ignition timing at medium speed and normal rotation,
A current-blocking type non-contact point for internal combustion engines that can ensure proper output of the engine and improve fuel efficiency, as well as prevent overspeeding of the engine by controlling the engine retardation above the set speed at high speeds. The purpose is to provide an ignition device.

For this reason, the present invention provides a non-contact ignition device including the trigger circuit, switching control circuit, ignition coil, and spark plug, and further provides the advance angle circuit to control the negative induced voltage of the primary coil of the ignition coil. a first capacitor for charging; a discharging circuit for discharging the charge of the first capacitor at a predetermined time constant; An overspeed prevention circuit comprising a switching element that is turned on when the capacitor is discharged, and a second capacitor that delays the supply of the trigger voltage to the switching control circuit when the switching element is turned on. Fig. 7 shows an embodiment of the present invention in which an overspeed prevention circuit H and an electronic component protection circuit I are connected to the circuit shown in Fig. 4, and the same components are given the same reference numerals. , the explanation thereof will be omitted. Above over-speed prevention circuit H
is as follows. 24 is a diode, 25 is a first capacitor, and 26 is a diode, which are connected in series between lines l ₁ and l ₂ . A thyristor 27 as a switching element and a second capacitor 2 are connected between the connecting midpoint of the resistor 15 and the base of the switching transistor 9 and the line _l2 .
A series circuit consisting of 8 is connected. 29,3
0 is a resistor and a capacitor connected in parallel between the cathode and gate of the thyristor. Further, the midpoint of the connection between the diode 24 and the capacitor 25 is connected to the cathode of the thyristor 27, and the midpoint of the connection between the capacitor 25 and the diode 26 is connected to the gate of the thyristor 27 via a resistor 31. Note that the resistors 29 and 31 constitute a discharge circuit that discharges the charge in the second capacitor 28 at a predetermined time constant. Note that the electronic component protection circuit I has the same configuration as that shown in FIG.

In the circuit having such a configuration, in the low speed, medium speed, and steady speed range of the engine, the capacitor 25 is charged to the polarity shown in the figure through the diodes 24 and 26 in the negative half cycle of the voltage of the primary coil 13a. Discharging occurs through the resistors 31 and 29 in the positive half cycle, and the charging/discharging time of the capacitor 25 reaches the positive half cycle of the primary voltage _a2 of the primary coil 13a, as shown in FIG. 8a. Therefore, even if a trigger signal is input to the gate of the thyristor 27 to turn it on, the operation of the transistor 9 of the switching control circuit B is not affected at all. In the figure, a ₁ is the charge/discharge voltage waveform of the capacitor 25, a ₂ is the primary voltage waveform of the ignition coil, and b is the trigger level of the thyristor 27.

However, when the engine speed reaches the set overspeed in the high speed range, the charging and discharging time of the capacitor 25 extends to within the positive half cycle of the primary voltage, as shown in FIG. 8b. Even when the primary voltage changes from negative to positive, the thyristor 27 remains on and the capacitor 28 is charged with a positive voltage. For this reason, switching control of the primary short-circuit current has been conventionally performed using a series circuit of the Zener diode 14 and the resistor 15 with the base of the transistor 9 as the midpoint, and the voltage division level of the resistor 7. Due to the charging time constant with the capacitor 28,
Since the cut-off timing of the primary short-circuit current changes rapidly, the ignition timing of the engine is also rapidly retarded. As a result, overspeeding of the engine is prevented.
Therefore, as shown in FIG. 10, the ignition timing control of the engine according to the present invention has an advance characteristic by the advance angle circuit F from the starting rotation range to the normal rotation range, and the overspeed prevention circuit operates at the set rotation speed in the high speed range. The ignition timing is suddenly retarded by the action of H. Note that instead of the resistor 29, a temperature compensation circuit of a thyristor 27 consisting of resistors 32, 33 and a thermistor 34 may be connected as shown in FIG.

Although not shown, either or both of the ignition coil protection circuit G and the electronic component protection circuit I can be connected to a circuit as shown in FIG.

As explained above, according to the present invention, it is possible to retard the ignition timing when starting the engine to improve startability, and to advance the ignition timing to the proper ignition timing of the engine at low speeds (before idling). It is possible to maintain the above-mentioned appropriate ignition timing that is approximately constant at medium speeds and normal rotations, ensuring appropriate output of the engine and improving fuel efficiency.Moreover, it is possible to retard the engine at or above the set rotation speed at high speeds. This provides the effect of preventing over-rotation of the engine.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional current interrupt type non-contact ignition device, Figure 2 is a characteristic diagram of the ignition timing of the circuit in Figure 1, and Figure 3 is a non-contact ignition device devised during the creation process of the present invention. A characteristic diagram of the ignition timing of the ignition device, FIG. 4 is a circuit diagram of the non-contact ignition device, FIG. 5 is a partially modified circuit diagram of the circuit, and FIG. 6 is a diagram devised during the creation process of the present invention. Circuit diagram of non-contact ignition device,
FIG. 7 is a circuit diagram of the non-contact ignition device of the present invention, and FIG.
Figures a and b are voltage waveform diagrams for explaining the operation of the overspeed prevention circuit, Figure 9 is a partially modified circuit diagram of the circuit in Figure 7, and Figure 10 is the ignition timing of the non-contact ignition device of the present invention. FIG. A...Trigger circuit, B...Switching control circuit, D...Ignition coil, E...Spark plug, 6...Programmable unidirectional transistor, 13a...Primary coil, 13b...
... Secondary coil, 14 ... Zener diode, 2
5...First capacitor, 27...Thyristor as a switching element, 28...Second capacitor.

Claims (1)

[Claims] 1 A programmable unidirectional system that turns on when the positive primary short-circuit current of the ignition coil is at its peak or slightly past its peak.
A trigger circuit having a transistor and supplying a trigger voltage when the programmable union transistor is turned on; a switching control circuit receiving the trigger voltage and interrupting the primary short-circuit current; A current-interrupting type internal combustion engine equipped with an ignition coil that induces a high voltage in a secondary coil when the primary short-circuit current is interrupted, and a spark plug that generates a spark in response to the high voltage of the secondary coil. The non-contact ignition device includes a Zener diode that breaks over when the positive induced voltage of the ignition coil reaches a set value, and when the Zener diode breaks over, the switching takes precedence over the trigger circuit. An advance angle circuit that supplies a trigger voltage to the control circuit is provided, and further includes a first capacitor that charges the negative induced voltage of the primary coil, and a discharge that discharges the charge of the first capacitor at a predetermined time constant. a switching element that is turned on when the first capacitor is discharged during a positive half cycle of the voltage induced in the primary coil; and a trigger for the switching control circuit when the switching element is turned on; 1. A non-contact ignition device of a current interrupting type for an internal combustion engine, characterized in that it is provided with an overspeed prevention circuit including a second capacitor for delaying voltage supply.