JPS632612Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is an ignition device for an internal combustion engine, particularly an ignition device for use in a small internal combustion engine such as a chain saw or a lawn mower, for example, in a state where teeth are not attached to the chain saw or the like. The present invention relates to an ignition device for an internal combustion engine that prevents the engine from running out of control even when the engine is about to run out of control.

Conventionally, misfire control methods and retard control methods have been known to prevent overspeeding of internal combustion engines. This misfire control system stops the spark plug from generating sparks when the engine overspeeds, but it generates a lot of vibration and noise, which can lead to damage to the engine in high-speed internal combustion engines, and it also generates raw gas. There is a risk of after-fire. For this reason, the retarded angle control method described above is being adopted. The retard control method is to suppress over-speed by retarding the spark ignition point in steps when the engine is over-speed. However, for example, if an overspeed condition occurs when the teeth of a chain saw are removed, that is, when the internal combustion engine is alone, the rotation speed may still increase even if the above-mentioned retard control is performed. be.

The purpose of the present invention is to solve the above problems, and performs the retard control when the first critical rotation speed is reached, and performs the misfire control when the second critical rotation speed is reached. It is an object of the present invention to provide an ignition system for an internal combustion engine in which the retard control function and the misfire control function can be easily added to an existing ignition system.

Figure 1 shows the configuration of one embodiment of the present invention, and Figure 2 shows the configuration of the first embodiment.
Figures 3A, B, and C are explanatory diagrams conceptually explaining the control mode according to the illustrated configuration. 4A, B, and C are explanatory diagrams for explaining the operation after reaching the first critical rotational speed, and FIG. 5 is an explanatory diagram for explaining the operation when the second critical rotational speed is reached.

In Fig. 1, 1 is a magnet generator, 2 is a magnetic means, 3 is a primary winding (power generation winding), 4 is a secondary winding,
5 is an ignition plug, 6 is a short circuit, 7 is a switching transistor constituting the short circuit 6, 8 is a control means for controlling the transistor 7 in the short circuit 6, 9 is a control transistor, 10 11 is a pulsar coil which is magnetically coupled with the magnetic means 2 and induces a voltage in phase with the primary winding 3, and 11 is an SCR which is turned on when the first critical rotation speed is reached. 12 is a triax which is turned on when the second critical rotational speed is reached and causes the control means 8 to perform misfire control. things, 13 to 1
7 represents a diode, 18 to 27 a resistor, and 28 to 31 a capacitor.

In the case of the present invention, as shown in FIG. 2, the ignition plug is ignited by the short circuit 6 and the control means 8 shown in FIG. 1 until the first critical rotational speed N1 is reached. When the critical rotational speed N1 is reached, the ignition timing is retarded in steps to prevent overspeeding. However, if the rotational speed continues to rise even after the retardation control, as shown in Figure 2, misfire control is performed at the second critical rotational speed N2 to force the rotational speed to rise further. Make sure to stop it.

Before explaining the retard control and misfire control, the normal ignition mode using the short circuit 6 and the control means 8 will be explained.

When the magnetic means 2 is rotated in response to the rotation of the internal combustion engine, a voltage is induced in the primary winding 3. Now, when a voltage is induced in the direction of arrow A in the figure, the transistor 7 is turned on via the resistor 26, and a substantial short-circuit current flows to the primary winding 3. When this short circuit current has a waveform 32 shown in FIG. 3A, the control means 8 also has a resistor 2.
2, 24, 25, the capacitor 30 is charged via the capacitor 30. When the terminal voltage of the capacitor 30 reaches a predetermined level, the transistor 9 is turned on, the base current to the transistor 7 is shunted by the transistor 9, and the transistor 7 is quickly turned off. The timing at which the transistor 7 is turned off is selected at time _t1 , which is near the time when the current 32 reaches its maximum in FIG. , secondary winding 4
A high voltage is generated and the ignition plug 5 is ignited.

When a voltage is induced in the primary winding 3 in the direction opposite to the arrow A shown in FIG. is resistance 2
5, 24, and 22.

Until the first critical rotational speed N1 is reached, the ignition plug 5 ignites at a desired timing and the internal combustion engine continues to rotate, as conceptually described above. Under the condition that the first critical rotational speed N1 is not reached, the pulsar coil 10 has a voltage of 3 as shown in FIG. 3B.
3 is induced, and this voltage 33 is applied to the resistors 18 and 19 via the diode 14, but the voltage at the voltage dividing point p is at a voltage level L1 sufficient to turn on the SCR 11 (Fig. 3B) , the SCR 11 is never turned on. Also, during the negative half-wave period of the voltage induced in the pulser coil 10, the capacitor 28 is charged to the polarity shown in FIG. Since the condition C) in FIG. 3 is not reached, the triax 12 is never turned on.

However, when the first critical rotation speed N1 is reached, the voltage 33 induced in the pulsar coil 10 also increases, as shown in FIG. do. For this reason, the SCR 11 is turned on at the timing of point q in the figure. When the SCR 11 is turned on at point q, the resistors 22 and 2 are turned on in the control means 8.
The current that is charging capacitor 30 via SCR 4 and 25 is shunted via SCR 11, and the timing at which capacitor 30 is charged to a predetermined level and transistor 9 is turned on is delayed. In other words, the engine speed is retarded as shown in FIG. 2, and a state in which the internal combustion engine attempts to rise above the first critical speed is prevented. However, the triax 12 is still not turned on.

4A, B, and C are explanatory diagrams illustrating the operation after reaching the first critical rotation speed, and the reference numerals in the figures correspond to those in FIG. 3. Even after the retard control as explained in connection with FIG.
The engine speed may attempt to increase beyond the critical rotation speed N1. In this case, the voltage 33 induced in the pulser coil 10 is clearly shown in FIG. 4B.
Needless to say, at point q,
SCR11 is turned on and retard control is working effectively. However, as shown in FIG. 4C, the voltage 34 of the capacitor 28 has not reached the voltage level L2 mentioned above, and the triac 12 is not turned on.

If the second critical rotational speed N2 is still reached even though the retardation control is performed in the state shown in Figure 4, the fifth
As shown in the figure. Note that Figure 5 is similar to Figure 3 C and Figure 4.
This figure may be considered to correspond to figure C. 2nd above
When the critical rotational speed N2 is reached, the voltage induced in the pulsar coil 10 also becomes larger than in the state shown in FIG. As a result, the capacitor 28 charged via the diode 13 shown in FIG.
voltage 34 reaches the voltage level L2 described above. In this case, the triac 12 is turned on at point r in the figure and remains on thereafter. While the triax 12 continues to be on, the control means 8 controls the resistor 2 as described above.
The current charging capacitor 30 via 2, 24, 25 will be completely shunted by triac 12, and the voltage on capacitor 30 will no longer rise and turn on transistor 9. For this purpose, the transistor 7 in the short circuit 6
remains on during the entire period from when the voltage induced in the primary winding 3 begins to move in the direction of arrow A in FIG. 1 until it reverses. Therefore, 1
The current flowing through the next winding 3 is no longer cut off rapidly, and the ignition of the ignition plug 5 is stopped.

As explained above, according to the present invention, when the second dangerous rotational speed is reached even if an attempt is made to increase the rotational speed beyond the first dangerous rotational speed, the ignition at the ignition plug is forcibly stopped, and some raw gas Even if problems such as the release of fuel occur, the runaway of the internal combustion engine can be stopped. In the case of the present invention, for any ignition device having an existing control means and short circuit, a retard control circuit section (for example, based on the SCR 11) and a non-ignition control circuit section (for example, a tri-arc control circuit section)
2) is sufficient, and the existing ignition system can be easily improved.

[Brief explanation of drawings]

Figure 1 shows the configuration of one embodiment of the present invention, and Figure 2 shows the configuration of the first embodiment.
Figures 3A, B, and C are explanatory diagrams conceptually explaining the control mode according to the illustrated configuration. 4A, B, and C are explanatory diagrams for explaining the operation after reaching the first critical rotational speed, and FIG. 5 is an explanatory diagram for explaining the operation when the second critical rotational speed is reached. In the figure, 1 is a magnet generator, 2 is a magnetic means, and 3 is 1
Next winding (power generation winding), 5 is a spark plug, 6 is a short circuit,
8 is a control means, 10 is a pulsar coil, 11 is a
An SCR that constitutes a retard control circuit section,
Reference numeral 12 represents a triax which constitutes a non-ignition control circuit section.

Claims (1)

[Scope of utility model registration request] comprising a magnetic means for generating a moving magnetic field in response to the rotation of an internal combustion engine, a power generation winding magnetically coupled to the magnetic means, a control means for controlling the voltage and current of the power generation winding, and an ignition means, In an ignition device for an internal combustion engine, the voltage and current induced in the power generation winding by the magnetic means are controlled by the control means to ignite the ignition means, which is magnetically coupled to the magnetic means. Parsa to be done
A short-circuit circuit that includes a coil and short-circuits a predetermined forward current of the voltage induced in the power generation winding, a control means that opens the short-circuit circuit at a predetermined timing, and a control means that A retard control circuit section that delays the timing in response to the voltage from the pulsar coil; and a non-ignition control circuit section that disables the open control function of the control means in response to the voltage from the pulsar coil. The retard control circuit is activated when the rotational speed of the internal combustion engine reaches a predetermined first dangerous rotational speed, and the rotational speed of the internal combustion engine reaches a predetermined second dangerous rotational speed. An ignition system for an internal combustion engine, characterized in that the non-ignition control circuit section is activated when the number reaches a certain number.