JPS622299Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an internal combustion engine ignition device used for example in an outboard motor.

Internal combustion engines used in outboard motors require special ignition timing characteristics compared to other internal combustion engines. In other words, at the time of starting, it is approximately 5 degrees before top dead center (hereinafter referred to as BTDC) from the viewpoint of startability and prevention of kicking, during high-speed rotation, approximately 25 degrees BTDC from the point of view of output, and further during low-speed rotation called trolling. , an ignition timing of about 5 degrees after top dead center (hereinafter referred to as ATDC) is required for rotational stability. Conventionally, this demand has been met by mechanically rotating the ignition timing detection section of the internal combustion engine ignition system, but this requires a complicated mechanism, increases costs, requires maintenance, and is difficult for the user to operate after starting. When moving to trolling, there are many drawbacks such as the need to rotate the ignition timing detector. In addition, as an electric advance type ignition system that was adopted to solve these drawbacks, for example,
As shown in the publication, it is possible to change the ignition timing by switching the ignition position between starting and after starting, but changing the ignition timing immediately after starting is not desirable from the perspective of continuing engine rotation.
For this reason, it is not possible to simultaneously satisfy startability and rotational stability.

In view of the current situation, it is an object of the present invention to provide an electrical advance type internal combustion engine ignition device that satisfies both startability and rotational stability.

This invention will be explained in detail below based on the embodiment shown in the drawings.

FIG. 1 is an electric circuit diagram showing an embodiment of this invention. In the figure, 1 is a generator coil attached to a magnet generator driven by an engine and generates an AC output in synchronization with engine rotation, and 2 is a magnet. A signal coil that is attached to the generator and generates an AC output in synchronization with engine rotation; 3 is a diode that rectifies the AC output of the generator coil 1; 4 is a capacitor that is charged by the rectified output of the diode 3; 5 is a capacitor of the capacitor 4; An ignition coil that receives an electric charge; 6 a spark plug that receives the secondary voltage of the ignition coil 5 and discharges sparks; 7 a diode connected in parallel to the ignition coil 5; A diode that conducts a half-cycle output, which does not contribute to
9 is a resistor that generates a voltage drop due to the output flowing through the diode 7, and 10 is a thyristor that is a semiconductor switching element that discharges the charge of the capacitor 4 to the ignition coil 5 in response to the voltage drop of the resistor 9 or the output of the signal coil 2. , 11 is a diode that passes the discharge current of the capacitor 4 when the thyristor 10 is conductive, 12 is a diode that guides the voltage drop generated in the resistor 9 from the gate of the thyristor 10 to the cathode, and prevents reverse current. 13 and 14 are connected in parallel with each other. A resistor and a capacitor connected in series between the diode 12 and the resistor 9 adjust the ignition timing. 15 is a diode that rectifies the AC output of the signal coil 2; 16 is a resistor that limits the rectified output of the diode 15 and adjusts the ignition timing; 17 is a diode that receives the voltage drop of the resistor 9; and 18
19 is a capacitor charged by the current flowing through the diode 17 and the resistor 18, and 20 is a semiconductor switching element that becomes conductive when the charging voltage of the capacitor 19 reaches a predetermined value. A thyristor, 21 is a resistor that limits the current flowing when the thyristor 20 is conductive, 22 is a resistor for discharging the capacitor 19, 23
is an ignition timing control circuit composed of the thyristor 20 and the like.

Further, a control circuit that controls conduction of the thyristor 20 is configured by a diode 17, resistors 18 and 22, and a capacitor 19.

Next, the operation will be explained. Assume that the engine has just been started and the thyristor 20 is in a non-conducting state. The AC output of the generator coil 1 is rectified by a diode 3 and charges a capacitor 4. The electric charge accumulated in the capacitor 4 is discharged to the ignition coil 5 through the thyristor 10 and diode 11, which are turned on at the ignition timing of the engine. When the electric charge of the capacitor 4 is discharged to the primary coil of the ignition coil 5, a high voltage is generated in the secondary coil, causing the spark plug 6 to spark. The diode 7 absorbs the back electromotive force generated in the ignition coil 5 and converts the spark from the ignition plug 6 into a DC discharge. The half wave of the output of the generator coil 1 that does not contribute to charging the capacitor 4 is energized to the diode 8 and the resistor 9, causing a voltage drop across the resistor 9.

The voltage drop across the resistor 9 is the gate of the thyristor 10, the diode 12, the resistor 13, and the capacitor 14.
This current causes a current to flow through the thyristor 1.
When the gate trigger current I _GT of 0 is reached, the thyristor 10 becomes conductive. Here, the resistor 13 and the capacitor 14 function to adjust the current flowing through the gate of the thyristor 10 to adjust the timing at which the thyristor 10 is triggered, that is, the ignition timing.

On the other hand, the AC output of the signal coil is connected to the diode 15.
The signal is rectified by the resistor 16 and flows through the gate of the thyristor 10 to trigger the thyristor 10.

Here, the resistor 16 functions to adjust the current flowing through the gate of the thyristor 10 to adjust the ignition timing.

As described above, the thyristor 10 is triggered by a composite signal of the voltage drop across the resistor 9 and the output from the signal coil 2. Here, the phase of the output from the signal coil 2 is advanced with respect to the voltage drop across the resistor 9. , and if the output of the signal coil 2 is set so that it does not reach the trigger level of the thyristor 10 unless the rotation speed reaches the set rotation speed N or more, the ignition timing is determined by the voltage drop across the resistor 9 during low speed rotation, and the setting When the engine rotates at a high speed of N or more, the signal coil 2 determines the ignition timing.

An example of this characteristic is shown in Fig. 2. Below the set rotation speed N, the characteristic will be between points a and b, and above the set rotation speed N, the characteristic will be between points c and d. This will improve startability and engine output characteristics at high speeds. Satisfied. Next, ignition timing control circuit 2
3, but immediately after the engine starts, capacitor 1
9 is not charged, so the terminal voltage is low and does not reach the gate trigger voltage of thyristor 20, so thyristor 20 is in a non-conducting state. As time passes after the engine is started, the capacitor 19 is charged by the current flowing through the diode 17 and the resistor 18, and the terminal voltage gradually rises, and when this reaches the gate trigger voltage of the thyristor 20, the thyristor 20 becomes conductive. When the thyristor 20 becomes conductive, the current that had been flowing through the resistor 9 is shunted to the thyristor 20 and the resistor 21. Here, the internal resistance of the generating coil 1 is usually several hundred ohms, whereas the resistors 9 and 21 are usually selected to be several tens of ohms, so the magnitude of the current flowing through the generating coil is almost the same as the internal resistance value of the generating coil. Since it is determined depending on the time, it becomes an almost constant value. That is, due to conduction of the thyristor 20,
The current flowing through the resistor 9 decreases by the amount of current flowing through the thyristor 20, and the voltage drop also decreases.

Here, if the engine speed is equal to or lower than the set rotation speed N, the voltage drop across the resistor 9 decreases due to conduction of the thyristor 20, and the gate current of the thyristor 10 decreases, resulting in a delay in the ignition timing. To explain this using the waveform diagram in FIG. 3, 24 shown in FIG. 3A is the voltage between point g in FIG.
25 is the voltage drop across the resistor 9 when the thyristor 20 is conductive, 26 shown in FIG. is the gate trigger current I of the thyristor 10
It is _GT . As shown in FIG. 3B, the timing at which the thyristor 10 is triggered is delayed by an angle θ due to the conduction of the thyristor 20. Therefore, as shown in FIG. 2, the ignition timing characteristic becomes the characteristic of points e to f when the thyristor 20 is conductive in the portion below the set rotational speed N, thereby achieving satisfactory rotational stability at low speeds. Furthermore, since the point between points c and d is triggered by the output of the signal coil 2, it is not affected by the conduction of the thyristor 20 and does not change at all.

Note that the time it takes for the thyristor 20 to become conductive after starting can be varied by the resistor 18 and capacitor 19, and the angle θ in FIG.
can be varied by the resistor 21, and according to experiments, the angle θ can be varied up to about 10°. When the engine is stopped, the output of the generator coil 1 becomes zero and the capacitor 19 is not charged but is discharged by the resistor 22. Therefore, when the engine is restarted, the ignition timing is controlled by the same operation again. In addition, although the ignition timing control circuit shown in Fig. 1 detects the passage of time after starting and performs control, it is also possible to operate the ignition timing control circuit by detecting the temperature of the engine. As shown in the figure. In the figure, 29 is a resistor, 30 is a thermistor attached to the engine, and a voltage divided by the resistor 29 and the thermistor 30 is applied to the gate of the thyristor 20. When the engine is started, the temperature of the engine is low and the resistance of the thermistor 30 is large, so the gate voltage of the thyristor 20 is low and the thyristor 20 is not triggered. When the engine starts and the engine temperature rises, the resistance value of the thermistor 30 decreases, so the thyristor 2
The gate voltage of 0 increases, and when it exceeds the gate trigger voltage, the thyristor 20 becomes conductive.

In addition, in this circuit, if the engine is restarted immediately after the engine has stopped and the engine temperature has not decreased, the thyristor 20 becomes conductive, so the engine will start with a delayed ignition timing, but when the engine temperature is high, it will be easier to start. Therefore, starting performance does not deteriorate.

As described above, this invention detects the elapsed time after the engine starts or the engine temperature and automatically switches the ignition timing, so it is possible to achieve optimal ignition timing characteristics in all areas during starting, trolling, and high speed. I can do it. Further, since no mechanical rotating parts are required, the cost can be reduced, maintenance is easy, and handling is easy for the user, which has great effects.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram showing an embodiment of the present invention;
Fig. 2 is an ignition timing characteristic diagram of the circuit shown in Fig. 1, Fig. 3 is a waveform diagram for explaining the operation of the circuit shown in Fig. 1, and Fig. 4 is an electrical diagram showing another embodiment of this invention. It is a circuit diagram. In the figure, 1 is a generator coil, 2 is a signal coil, 3, 7, 8, 11, 12, 15, 17 are diodes, 4, 14, 19 are capacitors, 5 is an ignition coil, 6 is a spark plug, 9, 13 ,16,1
8, 21, 22, 29 are resistors, 10, 20 are thyristors, 23, 31 are ignition timing control circuits, and 30 is a thermistor. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] (1) A power generation coil that generates AC output in synchronization with the rotation of the engine, a signal coil, a capacitor that is charged by the half-wave output of one of the power generation coils, and a power generation coil that generates AC output in synchronization with the rotation of the engine. A resistor for energizing the other half-wave output, a switching element connected in parallel with this resistor, a control circuit that turns on the switching element when the engine reaches a predetermined state after the engine has started, and the resistor when the engine is rotating at low speed. A thyristor is triggered to the retard side as the voltage drop decreases, and is triggered by the signal coil output when the engine rotates at high speed, and an ignition coil that discharges the charge in the capacitor by conduction of the thyristor. internal combustion engine ignition system. (2) The internal combustion engine ignition system according to claim 1, wherein the control circuit controls the switching element to be conductive after a certain period of time has elapsed after starting the engine. (3) The internal combustion engine ignition system according to claim 1, wherein the control circuit controls the switching element to be conductive when the engine temperature is higher than a predetermined temperature.