JPS631008Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a non-contact ignition device for an internal combustion engine that uses a magnet generator as an ignition power source.

Conventionally, in order to provide a current-blocking ignition device that uses inexpensive transistors, the voltage drop when the transistor is turned on is detected by a voltage divider circuit made of resistors and the control semiconductor element is controlled without using an independent timing sensor. It is generally used to ignite the fire.

However, the above-mentioned conventional engine has a drawback that the starting rotation speed for ignition is high and the starting performance of the internal combustion engine is poor.

In order to solve the above-mentioned drawbacks, the present invention detects the ignition timing at low speed by detecting the almost maximum value of the forward voltage of the transistor due to the primary voltage of the ignition coil using a series circuit of a resistor and a transistor, and detecting the voltage drop across the resistor. When the primary voltage of the ignition coil that charges the capacitor exceeds the maximum value, the charged charge of the capacitor operates the semiconductor switching element to shut off the transistor, and the ignition timing at medium and high speeds is set as follows.
The primary voltage of the ignition coil is detected by a voltage divider circuit made of resistors, and its output terminal is connected to a semiconductor switching element. When the primary voltage reaches a set value, the semiconductor switching element is operated to determine the value, and as it rotates, By switching the ignition timing detection method,
The starting rotation speed can be lowered, and the secondary voltage can be increased as the rotation increases after the operation starts, and the primary current can be kept almost constant during medium speeds, so that the primary voltage and secondary voltage are not excessively high. It is an object of the present invention to provide a non-contact ignition device for an internal combustion engine, which can maintain a substantially fixed advance angle until a set rotation after the start of operation and gradually advance the advance angle after the set rotation.

The embodiments of the present invention shown in the drawings will be described above. In the first embodiment shown in FIG. 1, when a four-pole magnet generator is used, the primary coil 1a of the ignition coil 1 provided in the magnet generator has two cycles per rotation of the rotor of the magnet generator. AC voltage is generated. Now, when the generated output of the primary coil 1a rises in the direction of the arrow in the figure, the circuit of primary coil 1a → ground → resistor 3 → base/emitter of transistor 2 → resistor 7 → primary coil 1a connects the base to transistor 2. A current flows, transistor 2 conducts, and the output of primary coil 1a is short-circuited via resistor 7, so that a short-circuit current flows. At this time, due to the voltage drop across the resistor 7, the thyristor 4, which is a semiconductor switching element,
Cathode gate/diode 10}→Capacitor 9 is charged in the circuit of capacitor 9. At low speeds, as the short circuit current increases, the charging pressure of the capacitor 9 increases, and when the short circuit current exceeds the maximum value,
Since the cathode potential (voltage across resistor 7) is lower than the gate potential of thyristor 4 (terminal voltage of capacitor 9), the charge in capacitor 9 is discharged in the circuit of capacitor 9 → gate and cathode of thyristor 4 → resistor 7. Then, the thyristor 4 is made conductive.
Then, by short-circuiting the base and emitter of transistor 2, the base current to transistor 2 is bypassed, and transistor 2 is abruptly turned off. Due to the sudden change in magnetic flux at this time, 1
A large induced voltage is generated at both ends of the secondary coil 1a, and along with this, a secondary voltage is generated in the secondary coil 1b due to transformer action, and an ignition spark is produced at the ignition plug 11. In this case, the ignition timing is almost fixed,
The secondary voltage has a magnitude almost proportional to the rotation speed.

When the engine speed increases and exceeds the set value, the output of the primary coil 1a of the ignition coil 1 increases with rotation, and by using this fact, the rising voltage of the primary coil 1a is divided into voltages made up of resistors 5 and 6. Detected by the circuit,
Before the thyristor 4 becomes conductive due to the discharge of the capacitor 9, an output higher than the gate trigger level is applied from the output end of the resistor 6 to the gate of the thyristor 4 via the diode 8 to operate the thyristor 4.
Light it as above. In this case, the angle gradually advances due to the change in the rising waveform of the voltage, and the secondary voltage becomes approximately constant with respect to rotation.

In addition, the reverse output generated in the primary coil 1a of the ignition coil 1 flows to the resistors 6 and 5, the resistor 7, and the transistor 2 as a reverse transistor, and a harmful induced voltage is generated in the secondary coil 1b due to armature reaction. Prevent this from happening.

The above operation is repeated, and two fires are fired per rotation of the magnet generator.

The second embodiment shown in FIG. 2 is different from the first embodiment in that the diode 8 is omitted and the gate and cathode of the thyristor 4 are connected by a resistor 12 instead of the diode 10.

Furthermore, in each of the embodiments described above, the ignition coil 1 is built into the magnet generator and this ignition coil also serves as the ignition power supply coil, but the ignition coil is separated from the magnet generator separately from the ignition power supply coil. The ignition coil may be provided with power separately supplied from an ignition power supply coil.

As described above, in the present invention, the ignition timing at low speeds is determined by adjusting the nearly maximum forward voltage of the transistor due to the primary voltage of the ignition coil to the resistor connected in series with the transistor and the voltage drop across this resistor. When the primary voltage of the ignition coil exceeds the maximum value, the charge charged in the capacitor operates a semiconductor switching element to determine the ignition timing at medium and high speeds. The primary voltage of the ignition coil is detected by a voltage divider circuit made up of multiple resistors, its output terminal is connected to a semiconductor switching element, and when the primary voltage reaches a set value, the semiconductor switching element is operated to determine the value. Since the detection method of ignition timing is switched as the ignition coil rotates, a simple configuration including a resistor and a capacitor ensures that the ignition timing is detected at low speeds by the charge charged in the capacitor when the primary voltage of the ignition coil exceeds the maximum value. By making the switching element conductive, the rotation speed at which the operation starts can be reduced, and since the primary current increases as the rotation speed increases after the operation starts, the secondary voltage increases as the rotation speed increases. In addition, from the set rotation speed, the voltage divider circuit causes ignition when the primary voltage reaches the set value, so at medium and high speeds, the primary current must be kept almost constant, and the primary voltage and secondary voltage must be adjusted. In addition, the ignition advance angle is almost fixed from the start of operation until the set rotation speed, and the ignition advance angle is gradually advanced beyond the set rotation speed.The ignition advance angle can be suppressed from becoming excessively large.Furthermore, the ignition advance angle can be achieved with a very simple structure. , which has the excellent effect of being able to be produced at low cost.

[Brief explanation of the drawing]

Figures 1 and 2 show the device of the present invention in the first and second
FIG. 3 is an electrical circuit diagram showing each example. 1...Ignition coil provided in the magnet generator, 1a...
...Primary coil, 1b...Secondary coil, 2...Transistor, 4...Thyristor forming a semiconductor switching element, 5, 6...Resistor forming a voltage dividing circuit, 7, 8, 9, 10, 12... …Resistor, diode, capacitor, diode, resistor.

Claims (1)

[Claim for Utility Model Registration] A magnet generator is used as an ignition power source, and a primary current is passed through a primary coil of the ignition coil through a transistor,
Thereafter, in a non-contact ignition device for an internal combustion engine that generates a high voltage in a secondary coil of the ignition coil by cutting off a transistor, the ignition device is connected in series to both ends of the primary coil via the transistor; a resistor to which current is supplied via the transistor; a capacitor connected in parallel to the resistor and to which current is supplied via the transistor; connected to one end of the resistor and one end of the capacitor, respectively; a semiconductor switching element for bypassing and cutting off the base current of the transistor when the voltage of the capacitor becomes higher than the voltage at one end of the resistor; and a plurality of semiconductor switching elements connected to both ends of the primary coil of the ignition coil. and an output terminal which is a connection point of these resistors, and when the machine rotation speed exceeds a set value, before the primary current of the primary coil reaches the maximum,
A non-contact ignition device for an internal combustion engine, comprising: a voltage dividing circuit for making the semiconductor switching element conductive when the primary voltage of the ignition coil detected by the output terminal exceeds a set value.