JPH0379550B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition system for an engine, and in particular, it charges a charging/discharging capacitor with the output of an exciter coil, and conducts a switching element connected to the charging/discharging capacitor. An engine in which the charge from a capacitor is supplied to the primary coil of the ignition coil, and the high voltage generated in the secondary coil of the ignition coil is applied to the spark plug, thereby generating a spark and igniting the engine. ignition device.

An engine ignition device using an exciter coil and a charging/discharging capacitor can ignite the engine without using a battery. Such ignition systems have therefore become widely used, especially in small engines. In order to reliably start the engine using such an ignition device, it is sufficient to increase the number of turns of the exciter coil. This is because when the engine speed is low, the more turns the exciter coil has, the higher the ignition energy can be obtained. However, when the number of turns of the exciter coil is large, the ignition energy gradually decreases as the engine speed increases, resulting in a problem that ignition cannot be performed stably in the high-speed rotation range. In addition, in such an ignition system, as the engine speed increases, the timing at which the primary current increases is delayed.
The drawback is that advance angle control becomes difficult, which limits engine output and reduces efficiency.

The present invention has been made in view of these problems, and it is possible to obtain high ignition energy over a wide range of engine rotations, and to advance the engine in stages when the engine rotation speed exceeds a predetermined rotation speed. It is an object of the present invention to provide an ignition device for an engine which has a corner angle, thereby improving efficiency.

In the present invention, a first exciter coil with a large number of turns and a second exciter coil with a small number of turns are connected in series with each other, and the positive terminals of the pair of exciter coils are both connected to a charging/discharging capacitor. A closed circuit is formed by connecting the primary coil of the ignition coil and a first thyristor to the charge/discharge capacitor, and a first capacitor is connected to the gate of the first thyristor. A second thyristor is connected between the negative terminal of the second exciter coil and the gate of the first thyristor so as to be parallel to the capacitor.
A thyristor is connected to the gate of the second thyristor, and a second capacitor that is charged by discharging the charging/discharging capacitor is connected to the gate of the second thyristor, and the first exciter coil and the charging/discharging capacitor are connected to each other. A third thyristor is connected between the third thyristor, and a third capacitor charged by the negative output of the first exciter coil is connected to the gate of the third thyristor. A light receiving element of a photocoupler is connected so as to short-circuit both ends of the capacitor, and a light emitting element of the photocoupler is connected in series with the second thyristor, so that the number of revolutions of the engine is a predetermined first revolution. When the output of the pair of exciter coils first rises to a negative value, the voltage of the second capacitor becomes equal to or higher than the gate trigger voltage of the second thyristor, and the rotation speed of the engine reaches a predetermined value. When a second rotational speed is reached, the voltage of the second capacitor when the output of the pair of exciter coils changes from the positive side to the negative side is equal to or higher than the gate trigger voltage of the second thyristor. It is.

The present invention will be explained below with reference to an illustrated embodiment.
FIG. 1 shows the rotational configuration of an engine ignition system according to this embodiment, and this ignition system is equipped with first and second exciter coils 1 and 2, and these coils 1 and 2 are mutually connected. connected in series. The positive side of the first exciter coil 1 having a large number of turns is connected to the positive side of a charging/discharging capacitor 5 via a thyristor 3 and a diode 4. On the other hand, the second type with fewer turns
The negative side of the exciter coil 2 is grounded and connected to the negative side of the charging/discharging capacitor 5 via the primary coil 7 of the ignition coil 6. A secondary coil 8 of the ignition coil 6 is connected to a spark plug 9. Further, a connection point between the pair of exciter coils 1 and 2 and a connection point between the diode 4 and the charging/discharging capacitor 5 are connected to each other via a diode 10. Further, a diode 11 is connected in parallel to the series circuit of the charging/discharging capacitor 5 and the primary coil 7.

Next, the advance angle circuit 12 provided in this ignition device will be explained. The advance angle circuit 12 is connected to a thyristor 13 for discharging the charge and discharge capacitor 5. That is, the cathode of the thyristor 13 is connected to the negative terminal of the exciter coil 2 via the varistor 14 and the diode 15. A series circuit of a diode 16 and a capacitor 17 is connected in parallel to the varistor 14, and a variable resistor 18 is connected in parallel to the capacitor 17. One end of the capacitor 17 is connected to the negative terminal of the second exciter coil 2 via a capacitor 19 and a diode 20, whereas the connection point between the diode 16 and the capacitor 17 is It is connected to the gate of a thyristor 22 via a resistor 21. The thyristor 22 is connected in series with a photodiode 23, and the cathode of the thyristor 22 is connected to the gate of the thyristor 13. Further, the connection point between the capacitor 19 and the diode 20 is connected to the gate of the thyristor 13 via a resistor 24. Further, the cathode of the varistor 14 is connected to a pair of exciter coils 1 and 1 through a diode 25.
It is designed to be connected to the second connection point.

Next, the switching circuit for the pair of exciter coils 1 and 2 will be explained. This switching circuit includes a thyristor 3 connected to the positive side of the first exciter coil 1, and the gate of this thyristor 3 is connected to a resistor. 28 and a capacitor 27 to the cathode of the thyristor 3. Furthermore, via the connection point between the capacitor 27 and the resistor 28, the resistor 29 and the diode 30,
It is connected to a connection point between a pair of exciter coils 1 and 2. And the above capacitor 2
7 has a photothyristor 3 in parallel to this.
Further, the cathode of the photothyristor 31 is connected to the connection point between the exciter coil 1 and the anode of the thyristor 3 via a diode 32.

Next, the operation of this ignition system having the above structure will be explained. As the magnet rotor rotates, the exciter coils 1 and 2 are arranged as shown in FIGS. 2A, 3A, and 4A by the time flux of the magnets provided in this rotor. This results in a power generation output with a waveform like this. In addition, Figure 2A, Figure 3A,
4A shows changes in the output voltages of the exciter coils 1 and 2 when the engine speed changes from low to high.
When the engine speed is low, the first negative part a of the outputs of the exciter coils 1 and 2 shown in Figure 2A creates a potential difference between both ends of the exciter coil 1, which has a large number of turns. In order to generate, exciter coil 1, diode 30,
A current flows through the resistor 29, the capacitor 27, the diode 32, and the exciter coil 1 in this order, and the capacitor 27 is charged by this current. The charge charged in the capacitor 27 flows in the order of the capacitor 27, the resistor 28, the gate of the thyristor 3, the cathode, and the capacitor 27, and a voltage higher than the gate trigger voltage is applied to the gate of the thyristor 3. This thyristor 3 is ON
The state will be changed.

In this way, when the thyristor 3 is in the ON state due to the charge of the capacitor 27, when the output of the exciter coil 1 turns to the positive side as shown by b in FIG. 2A, the output of the exciter coil 1 According to the anode of thyristor 3,
Current flows in this order through the cathode, the diode 4, the charging/discharging capacitor 5, the primary coil 7 of the ignition coil 6, and the exciter coil 2, and at this time, the charging/discharging capacitor 5 is charged. That is, when the engine speed is low, charging of the charging/discharging capacitor 5 for ignition is performed through the thyristor 3 by the output of the first exciter coil 1. Since the first exciter coil 1 has a large number of turns, it increases the ignition energy especially when the engine speed is low. In addition, since the number of turns is large, the starting performance of the engine is improved.

As the magnet rotor rotates, the outputs of the exciter coils 1 and 2 change from the plus side to the minus side, as shown in FIG. 2A. In the portion c where the rotational speed changes to the negative side, the following operation is performed when the engine speed is low. When the outputs of the exciter coils 1 and 2 are reversed to the negative side, current flows through the exciter coil 2, the diode 20, the capacitor 19, the diode 25, and the exciter coil 2 in this order. Capacitor 19 is charged by this current. When the capacitor 19 is charged, current flows through the exciter coil 2, the diode 20, the resistor 24, the gate and cathode of the thyristor 13, the varistor 14, the diode 25, and the exciter coil 2 in this order. What must be noted here is that even if the output of the exciter coil 2 turns negative, no gate current is supplied to the thyristor 13 until the capacitor 19 is charged. Therefore, as shown in Fig. 2A and B, the output of the exciter coil 2 is on the negative side c.
When the voltage reaches its peak, the thyristor 13 finally becomes conductive and the charge in the capacitor 5 is discharged.

Describing the operation of discharging the capacitor 5, the capacitor 19 is charged by the negative output of the exciter coil 2, and then when current is supplied to the gate of the thyristor 13 and the thyristor 13 becomes conductive, the capacitor 5, The anode and cathode of thyristor 13, varistor 14,
diode 15, primary coil 7 of ignition coil 6,
Current flows in the order of capacitor 5, and the current in primary coil 7 of ignition coil 6 changes rapidly. Therefore, a high voltage is induced in the secondary coil 8 of this ignition coil 6, and a spark is generated in the ignition plug 9 connected to the secondary coil 8 due to this high voltage. This causes the engine to ignite.

Further, due to the discharge of the charging/discharging capacitor 5, a current flows through the varistor 14, so that the capacitor 1
7 will be charged through diode 16. The charge in the capacitor 17 flows through a closed circuit consisting of the capacitor 17, the resistor 21, the gate and cathode of the thyristor 22, the gate and cathode of the thyristor 13, the varistor 14, and the capacitor 17, and is discharged. At the same time, part of the charge of this capacitor 17 is consumed by a variable resistor 18 connected in parallel to this capacitor 19. Therefore, the voltage across the capacitor 17 changes in a sawtooth pattern as shown in FIG. 2C.

What should be noted here is that when the engine speed is low and the outputs of the exciter coils 1 and 2 are small, the discharge of the capacitor 17 causes the gate of the thyristor 22 to uniaxially pass the gate trigger current. However, since the gate trigger current of thyristor 13 is larger than this, thyristor 13 is turned on at this time.
It does not become a state. At this time, the charging potential of the capacitor 17 is also low, and the voltage of the capacitor 17 becomes lower than the gate trigger voltage of the thyristor 22 before the first negative side output a of the exciter coils 1 and 2 rises. I end up. Therefore, when the engine speed is below the predetermined speed _n1 , switching from exciter coil 1 with a large number of turns to exciter coil 2 with a small number of turns is not performed.

In contrast, the engine rotation speed is the specified rotation speed.
If n exceeds ₁ , the output of exciter coils 1 and 2 will become slightly higher, and the time required for one cycle will be slightly shorter, so capacitor 1
The change in voltage of 7 is as shown in FIG. 3C. What should be noted in this graph is that even though the changes are in the same sawtooth pattern, the voltage across capacitor 17 when the outputs of exciter coils 1 and 2 first rise to the negative side is the gate trigger voltage of thyristor 22. This is what has happened. Therefore, at the gate of the second thyristor 22,
When the engine rotates once and the first negative voltage of the exciter coil 2 rises while a current greater than the gate trigger current is flowing from the capacitor 17, this negative voltage a causes the exciter coil 2 to rise. , photodiode 23, anode of thyristor 22, cathode of thyristor 22, thyristor 1
Current flows through the gate of No. 3, the cathode of No. 3, the varistor 14, the diode 25, and the exciter coil 2 in this order. The photodiode 23 emits light due to this current, and the photodiode 2
Photothyristor 31, which together with photocoupler 3 constitutes a photocoupler, becomes conductive. In this way, the photothyristor 31 is activated by the photodiode 23.
When the capacitor 27 becomes conductive, the thyristor 31 short-circuits both ends of the capacitor 27. Therefore, the charge in the capacitor 27 is discharged by the thyristor 31, and the supply of gate current from the capacitor 27 to the gate of the thyristor 3 is cut off.

In this way, when the engine speed reaches a predetermined speed and the photodiode 23 and photothyristor 31 turn off the thyristor 3, the charge/discharge capacitor 5 is turned off by the first exciter coil 1. Charging becomes impossible. Therefore, at this rotation speed _n1 , the exciter coils 1 and 2 are switched as shown in FIG. 5, and thereafter the charging/discharging capacitor 5 is charged by the second exciter coil 2. That is, when the output of the exciter coil 2 changes to the positive side and a voltage b is generated as shown in FIG. Current flows through the coil 7 and the exciter coil 2 in this order, and the charging/discharging capacitor 5 is charged.

The ignition operation by discharging the charging/discharging capacitor 5 is the same as when the engine speed is low, and when the output of the exciter coil 2 changes to the negative side and reaches the part c in FIG. First, the capacitor 19 is charged by the negative output. Then, after this, exciter coil 2
The negative output of the thyristor 13 is supplied through the resistor 24 to the gate of the thyristor 13.
Switch to ON state. As a result, the charge stored in the charging/discharging capacitor 5 is discharged, and as a result, a high voltage is induced in the secondary coil 8 of the ignition coil 6, and a spark is generated by the ignition plug 9. become.

Therefore, when the engine speed increases further and exceeds the predetermined speed n2, the output of the exciter coil ₂ increases and the time required for one cycle is further short-circuited, so that the voltage across the capacitor 17 is The change in is shown in FIG. 4C. As is clear from this graph, even with the same sawtooth shape, the output of exciter coil 2 changes from the positive side to the negative side, and from part b to c
This capacitor 17 when changing to the part of
It must be noted that the voltage of the thyristor 22 is greater than or equal to the gate trigger voltage of the thyristor 22.
Therefore, if the engine rotates once and the output of the exciter coil 2 changes from part b to part c while a current greater than the gate trigger current is flowing from the capacitor 17 to the gate of the second thyristor 22, the output of the exciter coil 2 changes from part b to part c. A signal current is applied to the gate of the first thyristor 13 through the photodiode 23 and this second thyristor 22 . That is, when the output of the exciter coil 2 changes from the positive side to the negative side, the exciter coil 2, the photodiode 23, the anode of the thyristor 22, the cathode thereof, the gate of the thyristor 13, the cathode, the varistor 14, the diode 25, the exciter coil 2
A current flows in the order of , which causes the thyristor 13 to
becomes conductive, and the charging/discharging capacitor 5 is rapidly discharged. Therefore, a high voltage is induced in the secondary coil 8 of the ignition coil 6, a spark is generated in the ignition plug 10, and ignition is performed.

In this way, when the engine speed exceeds the second predetermined speed _n2 and the output of the exciter coil 2 changes from the positive side to the negative side, the capacitor 1
7 exceeds the gate trigger voltage of the second thyristor 22, the exciter coil 2
Immediately after the output voltage of the thyristor 13 changes from the positive side to the negative side, the thyristor 13 becomes conductive, and an ignition operation is performed. Therefore, compared to when the engine speed is low, the angle is advanced by the angle shown by θ in FIG. 4C. Therefore, the ignition angle changes with respect to the engine speed as shown in FIG. 6, and the ignition angle advances stepwise when the engine speed exceeds a predetermined speed _n2 .

As described above, according to the ignition device according to the present embodiment, when the engine rotation speed exceeds the predetermined first rotation speed _n1 , at this rotation speed the first exciter coil 1 to the second Switching to exciter coil 2 takes place. Since the first exciter coil 1 has a large number of turns, it generates high ignition energy in a region where the engine speed is low, and provides the ignition device with good startability. On the other hand, since the number of turns of the second exciter coil 2 is smaller than that of the first exciter coil 1, it prevents the ignition energy from decreasing in the high rotation speed region of the engine. Enables stable ignition operation.

Furthermore, according to the ignition system according to the present embodiment, when the engine speed exceeds the second speed _n2 , the advance angle is advanced in stages at this speed. Angular motion makes it possible to increase the efficiency of the engine. Further, according to the ignition device according to this embodiment, the advancing operation is mainly achieved by the capacitor 17 and the thyristor 22, and when the rotation speed exceeds a predetermined number, the exciter coil 2 Capacitor 1 when the output changes from the positive side to the negative side
7 exceeds the gate trigger voltage of the thyristor 22, thereby allowing stepwise advance angle. Therefore, with such a configuration, it is possible to perform the advance angle operation without using a signal coil by simply changing the circuit configuration. Therefore, it becomes possible to provide an ignition device that advances the angle with a simple configuration and at low cost.

Although the present invention has been described above with reference to an illustrated embodiment,
The present invention is not limited to the above embodiments, and various modifications can be made based on the technical idea of the present invention. For example, the present invention is not limited to the specific circuit configuration shown in FIG. 1, and various design changes are possible.

As described above, according to the present invention, when the engine rotation speed reaches a predetermined first rotation speed, when the output of the pair of exciter coils first rises to the negative side, the voltage of the second capacitor becomes In order to exceed the gate trigger voltage of the second thyristor, the light emitting element of the photocoupler connected in series with the second thyristor emits light when the output of the pair of exciter coils first rises to the negative side, and the photocoupler The light receiving element is switched to short-circuit both ends of the third capacitor. This makes the third
The thyristor becomes non-conducting and switches from the first exciter coil to the second exciter coil. Therefore, when the engine rotation speed is lower than the predetermined first rotation speed, the first exciter coil with a large number of turns generates high energy, ensuring good starting performance and increasing the engine rotation speed. When the number of rotations exceeds the first predetermined rotation speed, the second exciter coil with a smaller number of turns is used to prevent a drop in ignition energy and ensure stable ignition operation in the high rotation range. achieved.

Also, when the engine speed reaches a predetermined second speed, the output of the pair of exciter coils changes from the positive side to the negative side because the voltage of the second capacitor exceeds the gate trigger voltage of the second thyristor. As soon as the output of the exciter coil changes from the positive side to the negative side, the output of the second exciter coil is supplied to the gate of the first thyristor through the second thyristor, thereby immediately starting the ignition operation. will be carried out. Therefore, the advance angle is performed in stages at the predetermined second rotational speed, making it possible to improve the efficiency of the engine.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an engine ignition device according to an embodiment of the present invention, and FIG. 2 is a waveform diagram showing the operation of this ignition device when the engine speed is low.
Figure 3 is a waveform chart showing the operation of the ignition system when the engine speed is intermediate, Figure 4 is a waveform diagram showing the operation of the ignition system when the engine speed is high, and Figure 5 is a waveform diagram showing the operation of the ignition system when the engine speed is high. FIG. 6 is a graph showing changes in ignition energy of the ignition device with respect to engine speed. FIG. 6 is a graph showing changes in ignition angle with respect to engine speed. In addition, in the symbols used in the drawings, 1...first exciter coil, 2...second exciter coil, 3...third thyristor, 5...charging/discharging capacitor, 6...ignition coil, 7 ...Primary coil, 8...Secondary coil, 9...Spark plug, 12
... Advance angle circuit, 13 ... First thyristor, 17
... second capacitor, 19 ... first capacitor, 22 ... second thyristor, 23 ... photo diode, 26 ... exciter coil switching circuit, 27 ... third capacitor, 31 ... photo It is a thyristor.

Claims (1)

[Claims] 1. A first exciter coil with a large number of turns and a second exciter coil with a small number of turns are connected in series with each other, and the positive terminals of the pair of exciter coils are used for charging and discharging. A closed circuit is formed by connecting a primary coil of an ignition coil and a first thyristor to the charging/discharging capacitor, and connecting a first capacitor to the gate of the first thyristor. 1st
the second capacitor in parallel with the capacitor of
A second thyristor is connected between the negative terminal of the exciter coil and the gate of the first thyristor, and a second capacitor charged by discharging the charging/discharging capacitor is connected to the second thyristor. further connecting a third thyristor between the first exciter coil and the charging/discharging capacitor;
A third capacitor charged by the negative output of the first exciter coil is connected to the gate of the third thyristor, and a light receiving element of a photocoupler is connected to short-circuit both ends of the third capacitor. and the light emitting element of the photocoupler is connected in series with the second thyristor, and when the engine rotation speed reaches a predetermined first rotation speed, the output of the pair of exciter coils is When the voltage of the second capacitor becomes equal to or higher than the gate trigger voltage of the second thyristor when initially rising to the negative side, and the engine speed reaches a predetermined second speed, the pair of exciters An ignition device for an engine, characterized in that the voltage of the second capacitor when the output of the coil changes from the positive side to the negative side is equal to or higher than the gate trigger voltage of the second thyristor. 2. The engine ignition device according to claim 1, wherein the light emitting element of the photocoupler is composed of a photodiode, and the light receiving element of the photocoupler is composed of a photothyristor or a phototransistor.