JPS6140943Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an ignition control device for an internal combustion engine, and in particular, it maintains a power transistor in an on or off state above a set rotational speed of the internal combustion engine to prevent the internal combustion engine from overspeeding. Concerning what has been done.

Conventionally, various technologies have been provided as non-contact ignition devices for internal combustion engines, and the applicant has also proposed the first one.
We provide a non-contact ignition circuit as shown in the figure. In the following explanation, 1 is an ignition coil, a primary coil 1a and a secondary coil 1b.
are connected as shown in the figure through an iron core 1c, and each of these coils 1a and 1b has a small amount of thick conductor wire and a large amount of thin conductor wire wound twice around the same iron core 1c, and one terminal of these is connected in common. connected and grounded. Furthermore, a spark plug 2 is connected between both terminals of the secondary coil 1b. Above 1
A diode 3 is connected in parallel to both ends of the secondary coil 1a, and the collector and emitter of a power transistor are connected as shown. Further, a resistor 5 and the collector and emitter of a switching transistor 6 are connected to both ends of the primary coil 1a, and the base of the power transistor 4 is connected to a midpoint P between the resistor 5 and the collector. Furthermore, the primary coil 1
A phase setting circuit consisting of a resistor 7 and a capacitor 8 and a voltage dividing circuit consisting of a resistor 9 and a resistor 10 are connected in parallel to both ends of a. are connected to the anode and cathode of the programmable union transistor 11, respectively. In addition, a programmable union transistor 11 is connected to the connection midpoint R between the resistor 9 and the resistor 10.
gate is connected. 12 is a resistor connected between the base and emitter of the switching transistor.

In such an ignition circuit, one of the ignition coils 1 due to the rotation of the flywheel magneto.
A short circuit current is passed through the next coil 1a, and this current I
However, currents I ₀ , I ₁ , I ₂ , and I ₃ are shunted into the four circuits connected in parallel to the primary coil 1a, and depending on the shunted currents I ₂ and I ₃ , a current is generated at the connection midpoint Q. A voltage with a predetermined phase can be obtained for R, but since the terminal voltage is not high enough at the beginning of charging capacitor 8, Q
The voltage phase of the point lags that of the point R, and the programmable union transistor 1
1. The switching transistor 6 for small signals does not operate yet. Therefore, the power transistor 4 is turned on and supplies a short circuit current to the primary coil 1a through its collector and emitter. On the other hand, the charging voltage of the capacitor 8 charged by the shunted current I ₃ rises, and the programmable union transistor 11 is charged at a constant voltage value determined by the time constant of these capacitances and the resistance value 7. the anode voltage exceeds the gate voltage, then the programmable union transistor 11 conducts and conducts a current I _A at its cathode. This current I _A drives the switching transistor 6, which turns on and turns off the power transistor 4. Therefore, due to this gradual disconnection operation, the short circuit current flowing through the primary coil of the ignition coil is abruptly interrupted, and a high voltage with a large change is induced in the secondary coil 1b, causing the spark plug 2 generates a spark. Note that here, the switching transistor 6
is connected to the front stage of power transistor 4,
This is to sufficiently amplify the signal with a sharp rise obtained by the programmable union transistor 11, so that the power transistor 4 can operate correctly. In addition, the capacitor 8
is used to appropriately control the phase of the anode voltage with respect to the gate voltage of the programmable union transistor.

However, since such an ignition circuit is configured to drive the power transistor 4 with a switching signal that rises quickly, the ignition efficiency of the spark plug improves, the combustion pressure of the internal combustion engine becomes sufficient, and the rotation of the spark plug is increased. It progresses and becomes over-revised. Therefore, this over-speeding may damage the bearings and other components of the internal combustion engine, and the ignition circuit operates to advance the ignition timing, causing circuit destruction due to overrun. There is a risk.

The present invention was developed in view of the problems of the prior art, and in particular, it is necessary to control the power transistor so that the short-circuit current flowing to the primary coil of the ignition continues to be supplied or continues to be cut off. An object of the present invention is to provide an ignition control device for a non-contact ignition device in an internal combustion engine, which controls the operation and causes a spark plug to misfire at a set rotational speed of the internal combustion engine.

Embodiments of the present invention will be specifically described below with reference to the drawings. In FIGS. 2 and 3, the same components as those shown in FIG. 1 are given the same reference numerals.

Figure 2 shows 1 variable capacitor for 10 resistors above.
3 is connected, and a capacitor 14 is connected between the collector and base of the switching transistor 6.
A tank circuit consisting of a resistor 15 and a resistor 15 is connected.

Note that, of course, a fixed capacitor may be used as the variable capacitor 13.

According to this, the resistor 15 and capacitor 14
The tank circuit has positive phase lead characteristics for on/off control of the power transistor 4, switching transistor 6, and programmable union transistor 11 up to a rotation speed slightly beyond the normal rotation range of the internal combustion engine. By compensating for the phase lead characteristics, the trigger delay of the programmable unidirectional transistor 11 can be delayed until slightly beyond the normal rotation range. It is set to have a pressing effect.

In addition, at a rotation speed slightly beyond the normal rotation range, the capacitor 1
3 and the charging/discharging time constants of the resistors 10 and 9, the phase characteristics of the on/off control of the power transistor 4, the switching transistor 6, and the programmable disjunction transistor 11 turn negative, and the programmable disjunction - When the trigger of the transistor 11 gradually begins to be delayed and reaches the overspeed prevention set rotation speed of the internal combustion engine, the programmable unification transistor 11 is prevented from triggering due to the charging/discharging time constant of the phase setting rotation. The above programmable unification
In order to maintain the off state of the transistor 11, the switching transistor 6 is also turned off,
This is to maintain the on state of the power transistor 4.

Therefore, no excessively sharply changing current flows through the ignition coil 1, causing the spark plug 2 to misfire, reducing the rotation of the internal combustion engine, and preventing overspeed.

Figure 3 shows a diode 16 for the resistor 10 above.
and a capacitor 17 are connected in parallel, and their connection midpoint S is connected to the base of a switching transistor 6, and a resistor 18 and a capacitor 19 are connected between the collector and base of the switching transistor 6. A tank circuit is connected thereto, and the operation is similar to that of the embodiment shown in FIG. 2 above.

In addition, programmable unification
Needless to say, the gradual delay in the trigger of the transistor 11 means that the ignition timing is gradually retarded.

Therefore, the ignition timing is retarded to near top dead center, which is a certain amount behind the ignition timing to ensure optimum combustion efficiency and optimum output in the normal rotation range, and misfire occurs at the overspeed prevention setting rotation speed. Over-speeding can be easily prevented without damaging the various parts that make up the internal combustion engine.

As explained above, according to the present invention, the collector and emitter of the power transistor are connected to both ends of the primary coil of the ignition coil, respectively, and the base of the power transistor is connected to the base of the power transistor as described above.
Next, the collector and emitter of the switching transistor are connected to both ends of the coil through resistors, respectively, and the base of this switching transistor is connected to the cathode of the programmable union transistor. The anode and gate of the unidirectional transistor are respectively connected to a voltage divider circuit consisting of a resistor and a capacitor connected in parallel to the primary coil of the ignition coil, and a voltage divider circuit consisting of two resistors, and the programmable The anode and/or gate of the union transistor and the base of each of the power transistor and the switching transistor maintain the power transistor in an on or off state above a set rotational speed of the internal combustion engine. By connecting a phase setting rotation having a charging/discharging time constant circuit including a resistor and a capacitor, over-speeding of the internal combustion engine is effectively prevented, and wear and tear on internal combustion engine components such as bearings is prevented. Not only can damage be prevented, but also destruction due to ignition circuit overrun can be prevented, and furthermore,
Since it is not level detection, there is no variation, it is possible to prevent over-speed, and it is possible to provide a small and inexpensive ignition control device for an internal combustion engine.

[Brief explanation of drawings]

FIG. 1 is a non-contact ignition circuit diagram for an internal combustion engine, which is the basis of the present invention, and FIGS. 2 and 3 are circuit diagrams showing an ignition control device for an internal combustion engine according to the present invention. DESCRIPTION OF SYMBOLS 1... Ignition coil, 2... Spark plug, 4... Power transistor, 6... Switching transistor, 7, 8, 9... Resistor for voltage division circuit, 11... Programmable union transistor, 13, 17... Capacitor for phase setting circuit.

Claims (1)

[Scope of utility model registration request] The collector and emitter of a power transistor are connected to both ends of the primary coil of the ignition coil, and the base of the power transistor is connected to the collector and emitter of the switching transistor, which are connected to both ends of the primary coil through resistors. The base of this switching transistor is connected to the cathode of the programmable union transistor, and the anode and gate of the programmable union transistor are connected to the primary coil of the ignition coil. connected to a voltage divider circuit consisting of a resistor and a capacitor connected in parallel, and a voltage divider circuit consisting of two resistors, and further connected to the anode and/or gate of the programmable union transistor, the power transistor and the above. A phase setting rotary having a charge/discharge time constant circuit including a resistor and a capacitor is connected to the base of each of the switching transistors to maintain the power transistor in an on or off state at or above a set rotational speed of the internal combustion engine. An ignition control device for an internal combustion engine, characterized in that: