JPS6232286A - Ignitor for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide such characteristics for an ignitor that an ignition timing may be kept approximately constant in the specified revolution speed range of an engine while delayed or advanced in other revolution speed ranges by incorporating a pulser coil, a set speed detecting circuit and a signal supply control circuit. CONSTITUTION:A pulser coil Lp generates an ignition controlling signal Vp consisting of the primary- and secondary-polarity signals Vp1 and Vp2 when two inductive magnetic pole parts 10a and 10b pass the positions of a signal generator 14 respectively. Said magnetic pole parts include a set speed detecting circuit 2 and a signal supply control circuit 3, respectively, whereby determining the conductive position of a electric discharge control thyristor Th1 in accordance with the output signal of the pulser coil Lp within a specified engine speed range. Consequently, such characteristics can be obtained that an ignition timing may be kept approximately constant within the specified engine revolution speed (at a low speed used at the starting operation time or the like, for example) while the ignition timing may delayed or advanced within other engine revolution ranges.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capacitor discharge type ignition device for an internal combustion engine.

[Prior art J A capacitor discharge type ignition system for an internal combustion engine has an exciter coil installed in a generator that rotates in synchronization with the engine, and an exciter coil installed on the primary side of the ignition coil that uses the output of one half cycle of the exciter coil. The ignition energy storage capacitor to be charged, the discharge control thyristor provided to avoid discharging the charge of the ignition energy storage capacitor through the primary coil of the ignition coil when conductive, and a trigger signal to the discharge control thyristor. It consists of a thyristor trigger circuit that supplies

In this ignition device, a trigger signal is supplied from the trigger circuit to the discharge control thyristor to make the discharge control thyristor conductive, and the conduction of the thyristor causes the charge in the capacitor to be discharged to the primary coil of the ignition coil. A large magnetic flux change occurring in the ignition coil induces a high voltage for ignition in the secondary coil of the ignition coil.

In this type of ignition device, various methods are known for supplying a trigger signal to the discharge control thyristor. One of them is the output of the other half cycle of the exciter coil (ignition energy storage There is a device that uses the output of a half cycle in which charging is not performed) to trigger a discharge control thyristor when the output of the exciter coil reaches a certain trigger level.

・[Problem to be solved by the invention] When the thyristor is triggered using the output of the exciter coil during the half cycle in which the ignition energy storage capacitor is not charged as described above, the exciter Ignition characteristics are determined by the output characteristics of the coil. In other words, until the rotational speed of the engine reaches a certain level, the output of the exciter coil increases as the rotational speed increases, and its rise becomes faster. The position (ignition timing) at which the trigger level is reached advances as the rotational speed increases. However, when the rotational speed increases to a certain extent, the rise of the output of the exciter coil is delayed due to the armature reaction of the generator, so the ignition timing becomes delayed as the rotational speed increases. Therefore, in the conventional ignition system of this type, the ignition timing θi
(It is expressed as the angle taken from the engine's top dead center TDC to the advance side.

) with respect to the rotational speed N (ROM) is as shown in curve a in Figure 5, where the ignition timing advances continuously from low engine speeds, and continues to advance in the region above a certain rotational speed. It has a retarding characteristic.

Therefore, the above-mentioned conventional device cannot be used in cases where the characteristic of keeping the ignition timing substantially constant in a predetermined rotational speed range is required. Particularly in two-stroke engines, if an ignition system that advances the ignition timing when the engine is running at low speeds is used, the so-called Ketchen phenomenon occurs, in which the engine tends to reverse during the starting operation, resulting in poor engine startability. , it is required to keep the ignition timing almost constant at low speeds.

SUMMARY OF THE INVENTION An object of the present invention is to provide a capacitor discharge type ignition device for an internal combustion engine that can maintain the ignition timing of the engine constant in a predetermined rotational speed range.

[Means for solving the problems] As seen in FIG. 1 showing an embodiment of the present invention,
An exciter coil lex that induces an alternating current voltage in synchronization with the rotation of the internal combustion engine, an ignition coil ig, and an ignition coil i.
The ignition energy storage cone capacitor C1 is provided on the primary side of the ia and is charged to one polarity by the output of one half cycle of the exciter coil 1-ex. A discharge control thyristor Th1 provided to cause discharge through the primary coil J21 of the ignition coil, and an exciter coil L.
In an internal combustion engine ignition system equipped with a thyristor trigger circuit 4 that gives a trigger signal to the thyristor T when the output of the other half cycle of the ex reaches a certain trigger level, the ignition timing is kept constant in a predetermined rotational speed range. This makes it possible to obtain characteristics that maintain

In the present invention, the pulsar coil Lp outputs an ignition control signal consisting of a first polarity signal and a second polarity signal generated subsequent to the first polarity signal in synchronization with the rotation of the internal combustion engine. , an ignition timing control capacitor C2 that is charged to one polarity by the first polarity signal generated at the end of the pulsar coil [p], and a capacitor discharge that discharges the charge of this ignition timing control capacitor at a constant time constant. When the terminal voltage of the circuit (consisting of resistor R3 in the illustrated example) and the ignition timing control capacitor C2 reaches a certain level or higher, the first state (the cutoff state in the illustrated example) changes from the first state (the cutoff state in the illustrated example) to the second state. (in the illustrated example, the switching element S is in a conductive state) and the switching element S is in either the first state or the second state (in the example in FIG. 1, the switching element S When the pulser coil [p is in the first state), the thyristor Ti
A signal supply control circuit 3 is provided that allows a trigger signal to be supplied to the gate of 1t. When the rotation speed of the internal combustion engine reaches the set rotation speed, the time when the output of the other half cycle of the exciter coil Lex reaches the trigger level almost coincides with the time when the switching element changes from the first state to the second state. The discharge time constant of the capacitor discharge circuit is set so that

[Operation of the Invention] In the above ignition device, the ignition timing control capacitor C2 is charged by the signal Vpl of the first polarity generated first among the signals output by the pulsar coil, and when the peak of the signal passes, the capacitor C2 is charged. The charge on C2 is discharged with a constant time constant. While the terminal voltage of capacitor C2 exceeds a certain level, switching element S is held in the cut-off state, and when the terminal voltage of capacitor C2 becomes below a certain level, switching element S changes from the first state to the second state. become a state. The signal supply switch circuit 3 includes a switching element S
Only during the period in which the pulser coil is in the first state or the period in which the pulser is in the second state, a trigger signal is supplied to the thyristor Thl with the second polarity signal Vp2 of p. The time T1 until the terminal voltage Vc2 falls below a certain level after the charging of the capacitor C2 is completed is constant regardless of the rotational speed of the engine. On the other hand, after the charging of capacitor C2 is completed, the exciter coil eX
The time t until the output Ve2 of the other half cycle reaches the trigger level becomes shorter as the rotational speed between the rows increases.

It is assumed that the signal supply control circuit 3 is configured to allow the output of the pulser coil Lp to supply a trigger signal to the discharge control cyrisk when the switching element S is in the first state.

In this case, in a region where the engine rotational speed does not reach the set rotational speed, the output of the other half cycle of the exciter coil reaches the trigger level after the time when the switching element changes from the first state to the second state. When the output of the semiconductor switch generated after the pulser coil reaches a predetermined trigger level, a trigger signal is supplied to the discharge control thyristor. Since the rise of the output signal of the pulsar coil can be made sufficiently fast, the ignition timing becomes almost constant during the period when the trigger signal is given to the discharge control thyristor by the output of the pulsar coil.

On the other hand, in the region above the set rotation speed, the output of the other half cycle of the exciter coil reaches the trigger level of the discharge control thyristor while the switching element is in the first state, so the pulser coil LD A trigger signal is sent to the discharge control thyristor T by the second polarity signal Vp2 generated later or the output signal Ve2 of the other half cycle of the exciter coil lex, whichever signal reaches the trigger level first. will be given. Therefore, in this case, the ignition timing is determined by the output of the pulsar coil in the region below the set rotational speed, and the ignition timing is determined by the output of the other half cycle of the exciter coil in the region exceeding the set rotational speed.

Conventional ignition systems that use the output of the exciter coil during a half-cycle when the ignition energy storage capacitor is not charged to obtain the trigger signal for the thyrisk for discharge control did not have a pulsar coil, so the characteristics of ignition timing with respect to rotation speed is determined exclusively by the characteristics of the exciter coil, and only the characteristics shown in curve a in FIG. 5 could be obtained.

In contrast, according to the present invention, by providing a pulsar coil, a set speed detection circuit, and a signal supply control circuit, the conduction position of the discharge control thyristor is determined by the output signal of the pulsar coil in a predetermined rotational speed region. Therefore, as illustrated in FIG. 6A, B, or C, it is possible to obtain a characteristic in which the ignition timing is constant in a predetermined rotational speed range.

Examples] The present invention will be described in detail below with reference to the accompanying drawings.

In Figure 1, ex is an exciter coil installed in the magnet generator that is attached to the internal combustion engine and rotates synchronously with the engine, q is the ignition coil, Pq is the spark plug installed in the cylinder of the engine, and Ll) is the ignition coil installed in the engine cylinder. Pulsar coil installed in the signal generator attached to the engine, 1 is the ignition coil Lig
2 is a set speed detection circuit, and 3 is a signal supply switch circuit.

The exciter coil l ex is provided in a magnet generator, for example as shown in FIG. 4A. A four-pole flywheel magnet rotor 12 in which four magnets 11a to 11d are fixed to the inner periphery of a magnet generator internal coil 10, and an armature 13 in which an exciter coil 1-ex is wound around a stator core 13. It is equipped with The flywheel 10 is attached to the rotating shaft (usually the output shaft) of the engine (not shown), and the exciter coils l,
An AC voltage ■e having a waveform like this is output for 2 cycles per rotation.

Further, the signal generator includes, for example, as shown in FIG. 4, inductor magnetic pole portions 10a and 10b consisting of protrusions provided at symmetrical positions on the outer periphery of the flywheel 10, and a signal generator 14. The signal generator 14 has a permanent magnet 15 in the middle of the magnetic path.
This is a known type in which a pulsar coil Lp is wound around an iron core 16 provided with a pulsar coil [p is the inductor magnetic pole portion 10a,
0b passes the position of the signal generator 14, a pulsed signal Vl)1 of a first polarity and a pulsed signal VD of a second polarity generated following this signal of the first polarity.
The ignition control signal Vp consisting of 2 is output.

In this example, since the inductor magnetic pole part 10a has two thin films, the pulsar coil Lρ sends the ignition control signal p twice per revolution in synchronization with the rotation of the engine, as shown in FIG. 3B. Occur. The generation position of this signal Vp can be arbitrarily set depending on the mounting position of the signal generator.

The device shown in FIG. 1 includes a pulser coil Lp, a set rotational speed detection circuit 2, and an ignition signal supply control switch circuit 3.
The other parts are the same as the conventional device.

The primary current control circuit 1 is electrically connected to an ignition energy storage capacitor C1 which is provided on the primary side of the ignition coil Lig and is charged to one polarity by the output voltage e1 of one half cycle of the exciter coil Lex. When the discharge control thyristor Thl is provided to discharge the charge of the ignition energy storage capacitor C1 through the primary coil of the ignition coil, the output voltage Ve2 of the other half cycle of the exciter coil 1-ex is constant. Trigger level VZ
The thyristor trigger circuit 4 provides a trigger signal to the thyristor Th1 when the voltage reaches 1.

- One end of the exciter coil 1-ex is grounded, and the other end is connected to one end of a capacitor C1 through a diode D1 whose anode is directed toward the exciter coil. The other end of capacitor C1 is 1 of ignition coil Lig.
The other end of the primary coil β1 is connected to the anode of a diode D2'' whose cathode is grounded.The thyristor Th1 has its anode connected to the capacitor C1 and the anode of the diode D2. A resistor R1 is connected toward the C1 side, and is connected between the gate and cathode of the thyristor T and the former.

The thyristor trigger circuit 4 includes a diode D3 whose anode is connected to the ground terminal of the exciter coil Lex;
Zener diode ZD1 is connected between the cathode of diode D3 and the gate of thyristor Th1 with its cathode facing diode D3, and the anode is connected between the cathode of thyristor T and the non-grounded terminal of exciter coil lex. It consists of a diode D4 connected toward the cathode side of Th1, and a resistor R2 connected between the cathode of the Zener diode ZD1 and the cathode of the thyristor T.

The operation of the primary current control circuit 1 is as follows. That is, when the exciter coil Lex induces the output voltage Vel for one half cycle in the direction of the solid arrow shown in the diagram, a current flows through the diode DI, the capacitor C1, the primary coil J21, and the diode D2, and the capacitor C1 is charged to the polarity shown in the diagram. be done. The waveform of the terminal voltage Vc1 of this capacitor C1 is as shown in FIG. 3C.

Next, the 1 xciter coil 1-ex induces the output voltage Ve2 of the other half cycle in the direction of the dashed arrow shown in the figure, and when this voltage reaches a predetermined trigger level (in this example, the Zener level of the Zener diode ZD1) Vz1 or higher, the discharge occurs. A signal is supplied to the control thyristor T. Therefore, the thyristor Th1 becomes conductive, and the charge in the capacitor C1 is discharged through the thyristor Th1 and the primary coil β1.

This causes a large magnetic flux change in the iron core of the ignition coil, and a high voltage is induced in the secondary coil p2 of the ignition coil. Since this high voltage is applied to the ignition plug P(), a spark is generated at the ignition plug Pa, and the engine is ignited.

In this way, the rotation angle θ of the ignition timing when a trigger signal is supplied to the thyristor T by the output of the exciter coil.
The characteristics for this are as shown in curve a in FIG. That is, in the low and medium speed region of the engine, the output voltage ve2 of the other half cycle of the exciter coil lex increases as the rotational speed N increases, and the voltage 1fVe2 reaches the trigger level V.
Since the position at which Z1 is reached advances, the ignition timing θi advances as the rotational speed increases. On the other hand, in the high-speed region of the engine, the rise of the output voltage Ve2 in the other half cycle of the exciter coil Lex is delayed due to the armature reaction of the generator, etc., so the ignition timing θi is delayed as the rotation speed increases. It becomes angular.

The present invention is characterized in that a pulser coil LD, a set speed detection circuit 2, and a signal supply circuit 3 are added to the ignition device as described above.

One end of the pulsar coil Lp is grounded and connected to one end of the ignition timing control capacitor C2, and the other end of the capacitor C2 is connected to the non-grounded terminal of the pulsar coil lj) through a diode D5 with its anode facing the capacitor. ing. A resistor R3 is connected across the capacitor C2.
are connected in parallel, and the resistor R3 constitutes a discharge circuit for the capacitor C2. A Zener diode ZD2 is also connected in parallel to both ends of the capacitor C2 with its cathode facing the ground side. The gate of a field effect transistor constituting the switching element S is connected to the non-grounded terminal of the capacitor C2, and the source of the field effect transistor is grounded.

The signal supply control circuit 3 includes a PNP transistor TR1, a thyristor Th2, and a resistor R4.

The collector 3a of the transistor TRI is connected to the source of the field effect transistor, and the base 3b is connected to the drain of the field effect transistor. Further, the emitter of the transistor TRI is connected to the gate of the thyristor Th2, and a resistor R is connected between the anode and cathode of the thyristor Th2.
2 are connected. The anode 3C of the thyristor Th2 is connected to the non-grounded terminal of the pulse 1 coil Lp, and the cathode 3d of the thyristor Th2 is connected to the gate of the discharge control thyristor Th1.

In the above embodiment, when the pulser coil Lp outputs the signal Vpl of the first polarity, the ignition timing control capacitor C2 is charged to the illustrated polarity through the diode D5 by the signal of the first polarity.

When the peak of the signal Vp2 of the first polarity passes, the charge of the capacitor C2 passes through the resistor R3 at a constant time constant tli
Power up. Therefore, the waveform of the terminal voltage JfVC2 of the capacitor C2 becomes as shown in the third diagram. When the magnitude of the terminal voltage VC2 of the capacitor C2 is equal to or higher than the cutoff level Vt of the field effect transistor constituting the switching element S, the field effect transistor maintains the cut-off state (the switching element is in the first state). be). At this time, since the transistor TR1 is in a cut-off state, when the pulser coil Lp outputs the signal VD2 of the second polarity, the thyristor Th2 becomes conductive and a signal is supplied to the thyristor Thl. When the terminal voltage Vc2 of the capacitor C2 becomes lower than the cut-off level Vt, the field effect 1~transistor becomes conductive (the switching element S enters the second state), the transistor TR1 becomes conductive, and the gate of the thyristor Th2 is grounded. In this state, even if the signal Vp2 of the second polarity is generated, the ignition signal is not supplied to the thyristor Th2, so the thyristor Th2 is not conductive, and the trigger signal is supplied to the thyristor Thl by the signal of the second polarity of the pulser coil. This will prevent you from doing so.

Since the second polarity signal Vp2 of the pulser coil [p can rise sufficiently quickly, the second polarity signal Vp2 causes the thyristor T to pass through the thyristor Th2.
The ignition characteristics obtained when a 1 to RIGA signal is supplied to h1 are flat characteristics as shown by the chain line in FIG.

In the above device, when the rotational speed of the internal combustion engine reaches the set rotational speed, the time when the output voltage Ve2 of the other half cycle of the exciter coil reaches the trigger level Vt, and the switching element S changes from the first state to the second state. If the discharge time constant of the discharge circuit of the capacitor C2 is set so that the time at which the It is possible to obtain the characteristic of keeping the ignition timing constant in the rotational speed range.

For example, if the set rotation speed is set to N3 in Fig. 5, -
When the set rotational speed N3 is reached, the exciter coil lax
The output voltage VO2 of the other half cycle of is the trigger level V
so that the time when Z1 is reached and the time when the terminal voltage of capacitor C2 becomes less than the cutoff level Vt (
The discharge time constant of the capacitor C2 is set so that TI=t.

In this case, in the rotation range below the set rotation speed N3, the second
Before the signal Vp2 with the polarity of
A signal of polarity does not provide a trigger signal to the thyristor l''hl, and only the exciter coil l
A signal is supplied to the thyristor Th1 by the output voltage Ve2 of the other half cycle of ex. Therefore, in the region below the set rotational speed N3, the characteristic of curve a in FIG. 5 is obtained.

Furthermore, in a region exceeding the set rotational speed N3, the switching element S maintains the cut-off state until the time when the second polarity signal Vp2 is generated, so that the second polarity signal causes the thyristor T to trigger is now supplied, and the ignition characteristic becomes the characteristic shown by the chain line b- in FIG.

Therefore, the ignition characteristics in this case are as shown in FIG.

In this case, if you shift the position of the signal generator and set it so that the second polarity signal Vp2 of the pulser coil reaches the trigger level of the thyristor TI at the maximum advance position, it is possible to do so as shown by the broken line C in FIG. characteristics can be obtained.

Furthermore, when the set rotational speed is set to N1 in FIG. 5, characteristics as shown in FIG. 6B can be obtained.

In the above embodiment, the switching element S is in the first state! !
! When the signal supply control circuit 3 is in the cut-off state (in the above example), the signal supply control circuit 3 is allowed to supply a trigger signal to the thyristor Thl using the output of the pulser coil. It is also possible to configure the signal supply control circuit 3 to allow the output of the pulser coil to supply a trigger signal to the thyristor T when it is in the conductive state (in the example). An example of the configuration of the signal supply control circuit 3' used in this case is shown in FIG. 2, and in this example,
A transistor TR2 and resistors R5 and R6 are added to the circuit shown in FIG. 1, and the collector of the transistor TR2 is connected to the gate of the thyristor Th2, and the emitter is connected to the collector of the transistor TR1. Further, the base of the transistor TR2 is connected to the emitter of the transistor TR1, and the resistors R5 and R6 are connected between the base and base of the transistor TR2, and between the emitter and the base of the transistor TR2, respectively.

In the example shown in FIG. 2, when the terminal voltage of the capacitor C2 C2 is higher than the cutoff level Vt and the switching element S is in the cutoff state, the transistor TR2 becomes conductive and blocks the conduction of the thyristor Th2. A trigger signal is prevented from being supplied to Thl. When the terminal voltage Vc2 of the capacitor C2 reaches the cut-off level Vt, the switching element S becomes conductive and the transistor TR1 becomes conductive, so that the transistor TR2 is turned off. At this time, the thyristor Th2 becomes conductive, and the second polarity signal Vl of the pulser coil Lp)
2 allows a trigger signal to be supplied to the thyristor Thl.

When using the signal supply control circuit 3 shown in FIG. 2, if the set rotational speed is N2, in the region below the set rotational speed N2, the terminal voltage of the capacitor C2 becomes less than the cutoff level, and the switching element S is turned off. When the conductive state (second state) is established, a second polarity signal Vp2 of the pulser coil Ll is generated to supply a trigger signal to the thyristor T. In the area above the set rotational speed N2, the pulsar coil L
When the second polarity signal Vp2 of p is generated, the terminal voltage of the capacitor C2 is higher than the cutoff level Vt and the switching element S is in the cutoff state (first state).
The signal of the second polarity does not supply a trigger signal to the thyristor Th1, but the output of the other half cycle of the exciter coil lex supplies a trigger signal to the thyristor Th1. Therefore, the ignition characteristics at this time are shown in Figure 6C.
as shown by the solid line.

In addition, when using the signal supply control circuit 3 shown in FIG. 2, if the signal of the second polarity of the pulsar coil is set so as to reach the trigger level Vzl of the thyristor T at the maximum advance angle position θm, the signal of FIG. Characteristics as shown by broken line C can be obtained.

In the above example, the magnet generator has four poles, but the number of poles of the generator is arbitrary.

In the above example, ignition is performed twice with an angular interval of 180 degrees during one rotation of the engine, and the third
In the figure, sparks that occur at angles θ3 or θ4 are wasted flames, but in the case of a two-cycle engine, this wasted flame occurs near the end of the exhaust stroke, so it does not interfere with the operation of the engine.

In the above example, the pulsar coil controls the ignition control signal Vp to 1
The generation position of unnecessary sparks is controlled in the same way as the position of regular spark generation by causing two occurrences at 80 degree intervals, but in some cases, the pulsar coil is used for ignition control to control the regular ignition position. It is also possible to configure the circuit to output only the signal Vp (in the above example, only the inductor magnetic pole portion 10a is provided) and to control only the position where the regular spark is generated.

[Effects of the Invention] As described above, according to the present invention, there is provided a capacitor discharge type internal combustion system in which a trigger signal is supplied to a discharge control thyristor by the output of an exciter coil during a half cycle in which the ignition energy storage capacitor is not charged. In the engine ignition system, by adding a pulsar coil, a set speed detection circuit, and a signal supply control circuit, the conduction position of the discharge control thyristor can be determined by the output signal of the pulsar coil in a predetermined rotational speed range. This has the advantage that the ignition timing can be kept substantially constant in a predetermined rotational speed range and advanced or retarded in other rotational speed ranges.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a circuit diagram showing main parts of another embodiment of the invention, and Fig. 3 is a line explaining the operation of the embodiment of Fig. 1. Figure 4A is a schematic front view showing a configuration example of the magnet generator and signal generator used in the embodiment of the present invention, Figure 4B is an enlarged sectional view taken along the line B-B of Figure 4 △, 5 is a diagram showing the ignition characteristics obtained by the exciter coil and the pulsar coil in the embodiment of FIG. 1, and FIGS. 6A to 6C are diagrams showing various ignition characteristics obtained by the present invention.1 ...Primary current control circuit, 2...Setting speed detection circuit, 3...Signal supply li control circuit, 4...Thyristor trigger circuit, lex...Exciter coil, Ll) Pulser coil, Lig...・Ignition coil, C1...Capacitor for ignition energy storage, Th1...Thyristor for discharge control, C2...Capacitor for ignition timing control, S
...Switching element, R3...Resistance. Figure 5 N-1-r T i”

Claims (1)

[Scope of Claims] An exciter coil that induces an alternating current voltage in synchronization with the rotation of an internal combustion engine, an ignition coil, and an exciter coil that is provided on the primary side of the ignition coil and that generates an output of one half cycle of the exciter coil. an ignition energy storage capacitor charged to the polarity of the ignition energy storage capacitor; and a discharge control thyristor provided so as to discharge the charge of the ignition energy storage capacitor through the primary coil of the ignition coil when conductive.
and a thyristor trigger circuit that provides a trigger signal to the thyristor when the output of the other half cycle of the exciter coil reaches a certain trigger level, the ignition device for an internal combustion engine comprising: a pulser coil that induces an ignition control signal consisting of a signal of one polarity and a signal of a second polarity generated following the signal of the first polarity; an ignition timing control capacitor that is charged to the ignition timing control capacitor; a capacitor discharge circuit that discharges the charge of the ignition timing control capacitor at a constant time constant; a switching element that changes from a first state to a second state; and a second polarity signal of the pulser coil only during either a period in which the switching element is in the first state or a period in which the switching element is in the second state. and a signal supply control circuit that allows a trigger signal to be supplied to the gate of the thyristor at a time when the rotational speed of the internal combustion engine reaches a set rotational speed, the output of the other half cycle of the exciter coil is For an internal combustion engine, characterized in that the discharge time constant of the capacitor discharge circuit is set so that the time when the trigger level is reached and the time when the switching element changes from the first state to the second state substantially coincide. Ignition device.