JPS6228702Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a non-contact ignition system for internal combustion engines, and in particular advances the ignition timing at low speeds of the internal combustion engine using a pulsar coil and control circuit installed on the same core as the exciter coil. The present invention relates to a non-contact ignition device for an internal combustion engine that controls the ignition timing and retards the ignition timing during overspeed.

For example, magnet generator type ignition devices are widely used in internal combustion engines such as chain saws and special vehicles. The ignition power source for high-voltage current is obtained from a magnet generator without relying on batteries, and the low-voltage current generated by the magnet generator is taken out to the outside.
The ignition coil converts this into high voltage and supplies it to the spark plug.

By the way, during steady operation of an internal combustion engine such as a chain saw, the ignition timing in the internal combustion engine is set at around 30 degrees before top dead center to maximize the fuel efficiency of the air-fuel mixture. When the rotational speed of the internal combustion engine is low, such as during startup, if ignition is performed at the same ignition timing as described above, the internal combustion engine may rotate in reverse, making startup difficult. On the other hand, if the rotational speed of the internal combustion engine increases excessively, there is a problem in that it may cause damage to the internal combustion engine, burnout, or other accidents.

This idea was made in view of these conventional problems, and it improves the starting performance of the internal combustion engine by retarding the ignition timing sufficiently before top dead center in the low speed range such as when starting the internal combustion engine. The purpose is to continuously perform high-efficiency operation in the steady rotation range, and furthermore to restrict over-speed.

Therefore, in this invention, an exciter coil and a pulsar coil are provided on the same iron core, a voltage is generated in each coil by the rotation of a magnet provided on the rotor, and a capacitor is charged with the induced voltage of the exciter coil. The timing of the current flowing to the ignition coil is controlled using this voltage generated in the pulsar coil, a control circuit using this voltage, and a control circuit using the negative voltage of the exciter coil.

Embodiments of this invention will be specifically described below with reference to the drawings.

FIG. 1 is a circuit diagram specifically explaining the non-contact ignition device of this invention. In the figure, 1 is an exciter coil, to which a backflow prevention diode 3 is connected via a diode 2, and the primary coil of an ignition coil 5 is connected via a diode 2 and a first capacitor 4. There is. Further, a spark plug 6 is connected to the secondary coil of the ignition coil 5.

Further, one end of a resistor 7 is connected to the connection midpoint between the exciter coil 1 and the diode 2, and the other end of this resistor 7 is connected to the gate of a thyristor 8 and a cathode via a resistor 9. The anode of is connected to the midpoint between the second thyristor 10 and the diode 11, which are connected in parallel to the diode 3. 12 is a pulser coil connected in parallel to the thyristor 8; 13 is a second capacitor connected in parallel to this pulser coil 12 via a diode 14; 15 is a diode 14 and a second capacitor connected in parallel to the thyristor 8;
A first thyristor whose anode and cathode are connected between the gate of the thyristor 10, 16 is a resistor connected between the cathode and the gate of the first thyristor 15, and 17 is a resistor between the gate and the diode 11. This is a diode connected between the two. Further, 18 is a resistor connected between the cathode and gate of the second thyristor 10, and 19 is a diode connected in parallel to the series circuit of the diode 14 and the thyristor 15. 20 is a diode connected between the connection point between the exciter coil 1 and the diode 2 and the cathode of the thyristor 10; 21;
is a third thyristor connected between the cathode of the first thyristor 15 and ground, 22 is a resistor connected between the cathode and gate of this thyristor, and 2 is a resistor connected between the cathode and the gate of this thyristor.
3 and 24 are a resistor and a diode connected in series, and these are connected between the gate of the thyristor 21 and the anode.

FIG. 2 schematically shows a magnet generator including the exciter coil 1 and the pulsar coil 12. Each of these coils 1 and 12 is wound around a U-shaped iron core 31 in two poles, and each lead end of each of these coils is connected to each part of the control circuit 32 in FIG. 1 as shown. A rotor 33 rotates synchronously with the internal combustion engine, and has a magnet 34 inside and a magnetic pole 35 on its outer circumferential surface. 36 in the figure is a balance weight.

Next, the operation of this non-contact ignition circuit will be explained.

3a and 3b show the waveforms of the voltages generated in the exciter coil 1 and the pulsar coil 12, respectively, due to the rotation of the rotor 33. FIG. Now, when the rotational speed is low, such as when starting an internal combustion engine, the positive voltage P is the first in the positive half period of the exciter coil 1.
At the same time, the resistor 7 → pulsar coil 12 → diode 11 and resistor 7
→ diode 14 → second capacitor 13 → diode 11, and while charging the second capacitor 13, the gate of thyristor 8 is triggered.

At this time, a negative voltage Q is generated in the pulsar coil 12, but this negative voltage Q flows forward through the triggered thyristor 8, and the negative voltage Q of the pulsar coil 12 becomes the forward voltage of the thyristor 8. maintained.

Next, in the negative half cycle of exciter coil 1, a negative voltage P′ is generated, while in the pulsar coil 1
2, a positive voltage Q' is generated and charges the second capacitor 13. In addition, at this time, exciter coil 1
The negative voltage P' is not sufficient to cause the diac 24 to break over.

Here, when a negative voltage Q'' is generated in the pulser coil 12, since the thyristor 8 is in an off state at this time, the negative voltage flows through the diode 17 and the diode 19, triggering the gate of the first thyristor 15, The charging voltage of the second capacitor 13 triggers the gate of the second thyristor 10 through the first thyristor 15, making it conductive.
The charging voltage of the capacitor 4 is the second thyristor 1
0 and the ignition via diode 11.
The coil 5 is discharged, and accordingly, a high voltage is induced in its secondary coil, and a spark is generated in the spark plug 6. In addition, the pulsar coil 12 in FIG. 3b
The negative voltage Q'' reaches the trigger level of the first thyristor 15 at T ₁ and turns it ON, discharging the charging voltage of the second capacitor 13 to the gate of the second thyristor 10, turning it ON.At this point The first capacitor 4 is discharged for the first time at T _1. Figures 3c and d show the terminal voltage Vc ₁ characteristics of the first capacitor 4 and the terminal voltage Vc ₂ characteristics of the second capacitor 13 at this time. It is something.

In this way, the ignition operation is delayed to about 10 degrees before the top dead center of the internal combustion engine, and the starting performance of the internal combustion engine is improved.

On the other hand, when the rotational speed of the internal combustion engine exceeds the predetermined advance angle setting value, the negative voltage P' rises in the negative half cycle of the induced voltage of the exciter coil 1, causing the diac 24 to break. is applied to the third thyristor 2 via the resistor 23.
1 gate will be triggered. Therefore, the third thyristor 21 becomes conductive, and the second
The gate of thyristor 10 is also triggered and becomes conductive. Therefore, the charging voltage of the first capacitor 4 flows to the primary side of the ignition coil 5 via the thyristor 10 and the diode 11, thereby inducing a high voltage on the secondary side.

As a result, the trigger position of the second thyristor 10 changes from T ₁ at low speed rotation to as shown in FIG. 3e.
The engine moves to the _T2 position and the ignition timing becomes approximately 30 degrees before top dead center, allowing the internal combustion engine to be driven at a point of high efficiency.

Next, when the internal combustion engine rotates at higher speeds and approaches the set overspeed range, the exciter
Conversely, the induced voltage in the coil 1 will decrease.
Therefore, the negative voltage P' of the exciter coil 1 also decreases to below the breakover voltage of the diode 24, and the triggering of the third thyristor 21 is not executed, resulting in the same situation as at the time of low rotation as described above. The second thyristor 10 is triggered at timing _T1 . As a result, the ignition timing will be delayed, and the internal combustion engine will return to the specified speed range.
This can prevent accidents such as bearing seizure due to over-rotation.

As explained in detail above, according to this idea,
An exciter coil and a pulsar coil that induce voltages having substantially opposite phases in accordance with the rotation of the internal combustion engine, a first capacitor that charges the induced voltage of the exciter coil, and a discharge voltage of the first capacitor. an ignition coil that receives the pulse generator, a second capacitor that charges the induced voltage of the pulser coil, a first switching element that receives the discharge voltage of the second capacitor, and conducts the first switching element. a second switching element that enables discharge of the first capacitor, and a third switching element that is electrically connected in a steady rotation range below a set overspeed of the internal combustion engine and drives the second switching element. By configuring a non-contact ignition device, it is possible to ensure the combustion of the air-fuel mixture when starting the internal combustion engine, and it is also possible to operate with the same high efficiency as before at the set rotation speed. , the effect of preventing overspeed of the internal combustion engine can be obtained.

[Brief explanation of the drawing]

Figure 1 is a specific circuit diagram of the non-contact ignition device of this invention, Figure 2 is a schematic diagram of the magnet generator, and Figures 3 a, b, c, d, and e are time charts of voltages at various parts of the circuit. be. DESCRIPTION OF SYMBOLS 1... Exciter coil, 4... First capacitor, 5... Ignition coil, 6... Spark plug, 10... Second thyristor (switching element), 12... Pulsar coil, 13...
Second capacitor, 15...first thyristor (switching element), 21... third thyristor (switching element), 24... diax, 4...
...Magnet, 35...Magnetic pole, 36...Balance weight.

Claims (1)

[Scope of utility model registration request] An exciter coil and a pulsar coil induce voltages that are approximately opposite in phase to each other as the internal combustion engine rotates.
a coil, a first capacitor that charges the induced voltage of the exciter coil, an ignition coil that receives the discharge voltage of the first capacitor and supplies a high voltage to the spark plug, and an induced voltage of the pulsar coil. a second capacitor for charging;
a first switching element that becomes conductive in response to the discharge voltage of the second capacitor; a second switching element that enables the first capacitor to be discharged by the conduction of the first switching element;
conductive at a set steady rotational speed of the internal combustion engine;
A non-contact ignition device for an internal combustion engine, comprising: a third switching element that drives a switching element;