JPH0318696Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to an ignition system for an engine.

[Conventional technology]

A conventional device of this type is shown in FIG. In the figure, 1 is a generator coil of a magnet motor driven by an engine (not shown), and 2 is a signal coil that generates an ignition signal at the ignition timing of the engine, and is built in, for example, a magnet generator. 3 is a diode that rectifies the power generation 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 that is charged by the rectified output of the diode 3;
6 is an ignition coil, and 7 is a diode that short-circuits the half cycle of the power generation output of the generator coil 1 that does not contribute to charging the capacitor 4. 7 is a diode that receives the ignition signal from the signal coil 2 at the ignition timing of the engine and receives the charging charge of the capacitor 4. A thyristor is a semiconductor switching element that causes the ignition coil 6 to discharge, 8 is a spark plug that receives the secondary voltage of the ignition coil 6 and discharges sparkles, and 9 rectifies the ignition signal from the signal coil 2 to generate a thyristor 7.
10 is a stop switch that is connected to both ends of the generating coil 1 and stops the engine by bypassing the generated output; A thyristor is a semiconductor switching element that is connected to both ends of the power generation coil 1, with its anode (input end) connected to the output end of the power generation coil 1, and its cathode (output end) connected to the other end (ground side end) of the power generation coil 1. , 12 is a detection circuit that receives the output of the signal coil 2 and detects the rotational speed of the engine, and the output of this detection circuit is connected to the gate (control pole) of the thyristor 11. A diode 13 rectifies the output of the generator coil 1, and is connected to a capacitor 15 via a resistor 14. resistance 14
The connection point between the capacitor 15 and the capacitor 15 is connected to the power supply line of the detection circuit 12. The charge in the capacitor 15 serves as a power source for the detection circuit.

Next, the operation will be explained. The generated output of the generator coil 1 is rectified by a diode 3 to charge a capacitor 4, and is also rectified by a diode 13 to charge a capacitor 15 via a resistor 14. The half cycles that do not contribute to the charging of capacitor 4 are shorted by diode 5. The ignition signal generated in signal coil 2 at the engine ignition timing is
It is rectified by the diode 9 and applied to the gate of the thyristor 7, and the thyristor 7 becomes conductive, and the charge in the capacitor 4 is discharged through the thyristor 7 to the primary coil of the ignition coil 6. A secondary voltage is generated in the secondary coil of the ignition coil 6, causing spark discharge at the ignition plug 8. In addition, the output of the signal coil 2 is output from a detection circuit 1 that detects the engine rotation speed.
2 is input. The detection circuit 12 operates using the charge of the capacitor 15 as a power source, and when the engine rotation speed reaches a predetermined rotation speed, the detection circuit 12
Output voltage is output from the output of The above detection circuit 1
Since the output of thyristor 2 is connected to the gate of thyristor 11, when the output voltage of the detection circuit 12 is outputted, a voltage is applied to the gate of thyristor 11, and thyristor 11 becomes conductive. When the thyristor 11 becomes conductive, the power generation output of the generating coil 1 changes to the thyristor 1.
Since the capacitor 4 is short-circuited through the capacitor 1, no charge is accumulated in the capacitor 4, and no spark discharge occurs in the ignition plug 8. Therefore, the engine is not ignited above a predetermined number of revolutions, and the number of revolutions of the engine is limited, thereby limiting the speed of the engine or preventing over-rotation.

Further, in order to stop the engine in operation, it is sufficient to close the stop switch 10. That is, when the stop switch 10 is closed, the power generation output of the generating coil 1 is bypassed through the stop switch 10, so that no charge is accumulated in the capacitor 4, and therefore no spark discharge occurs in the spark plug 8. Because of this, the engine will stop working.

[Problem that the invention attempts to solve]

In this case, when the stop switch 10 is open, that is, when the engine is running, the generated output of the generator coil 1 (generally several hundred volts) is directly applied between the terminals of the stop switch 10 at all times. Therefore, although the stop switch 10 is insulated, if water or seawater is applied between the terminals of the stop switch 10, the insulation resistance between the terminals of the stop switch 10 will decrease. The leakage current becomes large, and the stop switch 10 becomes defective due to the current, for example, dielectric breakdown occurs, making it impossible to stop or restart the engine. Moreover, even if this does not occur, there is a defect in that the stop switch 10 is exposed to water or seawater and that if a worker touches it with wet hands, he or she may receive an electric shock.

Another method is shown in Fig. 4 of Japanese Patent Publication No. 59-45836. In this figure, 16
1 is a thyristor which is a semiconductor switching element whose anode is connected to the output end of the power generation coil 1 and its cathode is connected to the anti-ground terminal of the stop switch 10, 17 is a diode connected between the cathode and gate of the thyristor 16, and 18 is a power generation device. A resistor 19 is connected between the output end of the coil 1 and the gate of the thyristor 16, and a constant voltage diode, which is a constant voltage means, is connected between the gate of the thyristor 16 and the ground.The cathode of the constant voltage diode 19 and the resistor 17 The gate of the thyristor 16 and the cathode of the diode 17 are connected to the connection point. In this case, a constant voltage diode 19 is connected between the gate of the thyristor 16 and the other end of the generating coil 1 (the ground side in the example shown in FIG. 2), and the voltage between the terminals of the stop switch 10 is always maintained at a low voltage. Although this method can prevent breakage of the stop switch and electric shock, it still has the drawback that two thyristors 11 and 16 with high withstand voltages are required and are expensive.

This idea was made to solve the above-mentioned problems, and in addition to preventing damage to the stop switch 10 and electric shock, it also uses high withstand voltage for both semiconductor switching elements constituting the stop circuit and the voltage suppression circuit. The purpose is to obtain an inexpensive engine ignition system that does not require any additional equipment and has low pressure resistance.

[Means for solving problems]

The ignition device according to this invention includes a first semiconductor switching element connected to one end of the generating coil 1 of a magnet generator, and a stop switch connected to the output end of the first semiconductor switching element and the other end of the generating coil. , the voltage applied to the control pole of the first semiconductor switching element is made constant by a constant voltage means, and a second semiconductor switching element is connected between the output terminal of the first semiconductor switching element and the other end of the generating coil. The control pole of this second semiconductor switching element is controlled by the output of a detection circuit that detects the rotational speed of the engine.

[Effect]

In this invention, since the control pole of the first semiconductor switching element is set to a constant voltage, both ends of the stop switch connected to this first semiconductor switching element are always maintained at a low voltage, and furthermore, the control pole of the first semiconductor switching element is kept at a low voltage. A low voltage withstand voltage element can be used as the second semiconductor switching element connected to the element, and since the second semiconductor switching element is controlled by the output of the detection circuit that detects the engine speed, the speed limit of the engine can be reduced. Alternatively, the overspeed of the engine can be prevented.

[Example of idea]

An embodiment of this invention will be described below with reference to the drawings. In FIG. 1, 20 is a thyristor which is a second semiconductor switching element connected between the cathode of the thyristor 16 and the other end (ground side end) of the generating coil 1, and the anode (input end) of this thyristor 20 is a thyristor. connected to 16 cathodes,
The cathode (output end) of the thyristor 20 is connected to the other end (ground side end) of the generating coil 1 , and the gate (control pole) of the thyristor 20 is connected to the output end of the detection circuit 12 .

Next, the operation will be explained. First, when the stop switch 10 is opened, the generated output of the generator coil 1 is rectified by the diode 3, charges the capacitor 4, and is connected to the resistor 18 and the constant voltage diode 19.
Electricity is applied, rectified by the diode 13, and charged to the capacitor 15 via the resistor 14. Here, the resistor 18 can have a relatively large value because only the current required to trigger the thyristors 15 and 16 needs to flow.
The current flowing through 9 may be small. On the other hand, the charge stored in the capacitor 15 is supplied to a power source of a detection circuit that detects the rotation speed of the engine. resistance 18
Since the voltage dividing point between the voltage regulator diode 19 and the voltage regulator diode 19 is connected to the gate of the thyristor 16, the gate voltage (trigger voltage) of the thyristor 16 with respect to the ground becomes the voltage drop across the regulator diode 19. The cathode voltage of the thyristor 16 is approximately the same as the gate voltage. Therefore, the voltage across the terminals of the stop switch 10 becomes the voltage drop across the constant voltage diode 19.
Since the voltage drop of the voltage regulator diode 19 can be freely selected from about 1.50 to several tens of volts, it can be set to a low voltage. Therefore, since the voltage between the terminals of the stop switch 10 is low, even if water or seawater were to adhere to the stop switch 10, the leakage current would be extremely small, so there would be no dielectric breakdown of the stop switch 10 or electric shock. Further, the output of the signal coil 2 is input to a detection circuit 12 that detects the engine rotation speed. The detection circuit 12 outputs an output voltage when the engine rotational speed reaches a predetermined rotational speed. Since the output of the detection circuit 12 is connected to the gate of the thyristor 20, when the output voltage of the detection circuit is output, the thyristor 2
A voltage is applied to the gate of 0, and the thyristor 20 becomes conductive. When the thyristor 20 becomes conductive, the power generation output of the power generation coil 1 is short-circuited through the thyristor 16 and the thyristor 20, so that no charge is accumulated in the capacitor 4 and no spark discharge occurs in the spark plug 8. Therefore, the engine is not ignited above a predetermined number of revolutions, and since the number of revolutions of the engine is limited and does not exceed a predetermined number of revolutions, the speed of the engine is limited or overspeed is prevented. Here, the withstand voltage of the thyristor 20 only needs to be lower than the cathode voltage of the thyristor 16, and since the cathode voltage of the thyristor 16 is the voltage drop of the constant voltage diode 19, the withstand voltage of the anode and cathode of the thyristor 20 may be a low voltage. Therefore, inexpensive elements can be used.

Next, when the engine is stopped, when the stop switch 10 is closed, the voltage drop of the constant voltage diode 19 is applied between the gate and cathode of the thyristor 16, and the thyristor 16 becomes conductive. As a result, the power generation output of the generating coil 1 is short-circuited through the thyristor 16 and the stop switch 10, so that the capacitor 4 is no longer charged after the stop switch 10 is closed, so even if the thyristor 7 is conductive at the engine ignition timing, the ignition coil 6 is not charged. teeth,
Since no secondary voltage is generated, the engine will surely stop.

In the above embodiment, the thyristor 20 is provided in the second semiconductor switching element, but the transistor 20 may be provided in the second semiconductor switching element as shown in FIG. It has the effect of

[Effect of idea]

As described above, according to this invention, the control pole of the first semiconductor switching element connected to the output end and the other end of the power generation coil is made constant voltage to a low voltage, and the output end of the first semiconductor switching element is A stop switch and a second semiconductor switching element are connected to the other end of the generator coil, and the control pole of the second semiconductor switching element is controlled by the output of the detection circuit that detects the rotational speed of the engine. The voltage between the terminals of the stop switch can be lowered, the speed of the engine can be limited or overspeed can be prevented, and an element with a low withstand voltage can be used as the second semiconductor switching element, which has the effect of making the device inexpensive.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of this invention, Figure 2 is a circuit diagram showing another embodiment of this invention, and Figure 3 is a circuit diagram showing another embodiment of this invention.
4 are circuit diagrams showing a conventional device. In the figure, 1 is a power generation coil, 2 is a signal coil, 3, 5, 9, 13, 17 are diodes, 4,
15 is a capacitor, 6 is an ignition coil, 7, 11,
16, 20 are thyristors, 8 is a spark plug, 10
is a stop switch, 12 is a detection circuit, 14,1
8 is a resistor, 19 is a constant voltage diode, and 21 is a transistor. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A generator coil of a magnet generator, an ignition circuit that receives the output of the generator coil and generates an engine ignition voltage to the ignition coil, an input end of which is connected to one end of the generator coil. a first semiconductor switching element, a stop switch connected to the output end of the first semiconductor switching element and the other end of the generating coil, and a voltage applied to the control pole of the first semiconductor switching element as a constant voltage; turned into
a constant voltage means connected to a control pole of the first semiconductor switching device and the other end of the power generation coil; an input end connected to the output end of the first semiconductor switching device and an output end connected to the other end of the power generation coil; detects the second semiconductor switching element to be connected and the rotational speed of the engine;
An engine ignition system equipped with a detection circuit that outputs to the control pole of a semiconductor switching element. (2) The breakdown voltage of the second semiconductor switching element is the same as that of the first semiconductor switching element.
An ignition device for an engine according to claim (1) of the utility model registration, characterized in that the withstand voltage is lower due to the withstand voltage of the semiconductor switching element. (3) The engine ignition device according to claim (1), wherein the second semiconductor switching element is a thyristor. (4) The ignition device according to claim (1), wherein the second semiconductor switching element is a transistor.