JP4396265B2 - Ignition system for capacitor discharge internal combustion engine - Google Patents

Description

  The present invention relates to a capacitor discharge type ignition device for an internal combustion engine provided with a safety circuit having a function of stopping the internal combustion engine when an abnormality of the internal combustion engine is detected.

  As is well known, a capacitor discharge type ignition device for an internal combustion engine is provided with an ignition coil, an ignition capacitor provided on the primary side of the ignition coil and charged by the output of an ignition power supply, and an ignition signal. And a discharge switch for discharging the charge accumulated in the ignition capacitor through the primary coil of the ignition coil, and an ignition signal supply means for supplying an ignition signal to the discharge switch at the ignition timing of the internal combustion engine. The ignition operation is performed by applying a high ignition voltage induced in the secondary coil of the ignition coil by the discharge of the electric charge accumulated in the ignition capacitor to an ignition plug attached to the cylinder of the engine.

  On the other hand, in an internal combustion engine, if an abnormality occurs such that the remaining amount of lubricating oil is less than the allowable lower limit, the engine may be damaged if the engine continues to operate. Immediately stop the engine operation. Therefore, as shown in Patent Document 1, a safety circuit having a function of stopping the engine to stop the engine and performing an alarm operation when an abnormality occurs in the engine is attached to the ignition device. Things have been done.

  The safety circuit described in Patent Document 1 is controlled by an oil level detection switch that performs a detection operation when the liquid level of the lubricating oil of the internal combustion engine becomes lower than a set level, and the remaining amount of lubricating oil is insufficient. When the engine is ignited, the ignition operation is stopped and the alarm operation is performed. The output terminal of the ignition power supply is connected in parallel through a resistor having a low resistance value and is turned on. When the oil level detection switch is not performing detection operation, the output short circuit switch is kept off and the oil level detection switch detects the output short circuit switch that short-circuits the output terminals of the ignition power supply through a resistor. A switch control circuit that controls the output short-circuit switch so that the output short-circuit switch is turned on when the operation is performed, and the output short-circuit switch is turned on. Is constituted by a warning means for resistor is driven by the voltage developed across an alarm operation when Tsu. In the security circuit disclosed in Patent Document 1, a light emitting diode is used as an alarm means.

If a safety circuit as described above is provided, the output level of the ignition power supply is short-circuited when the oil level detection switch performs a detection operation when the level of the lubricating oil falls below the set level. The ignition capacitor is no longer charged and the ignition operation is not performed. As a result, the engine is misfired and stopped, so that it is possible to prevent the engine from being damaged due to the operation of the engine being continued in a state in which the liquid level of the lubricating oil is below the set level. Also, when the output short-circuit switch is turned on, the alarm means is driven by the voltage generated across the resistor to perform an alarm operation, so that the driver can be warned that the amount of lubricating oil has decreased.
JP 2002-70710 A (FIG. 6)

  In the above ignition device, the resistance value is sufficiently small as a resistor connected in series to the output short-circuit switch in order to reliably stop the internal combustion engine when the level of the lubricating oil drops below the set level. It is necessary to use something. If the resistance value of the resistor connected in series to the output short-circuit switch is large, the voltage between the output terminals of the ignition power supply cannot be lowered sufficiently when the output short-circuit switch is turned on. The ignition capacitor may be charged to a considerably high voltage, and an ignition operation may be performed. Further, if the resistance value of the resistor is made too small, the voltage generated across the resistor when the output short-circuit switch is turned on becomes low, so that the alarm means cannot be operated reliably. In the case where the alarm means is a light emitting diode, if the voltage across the resistor is insufficient, the amount of light emission is reduced, making it difficult to visually recognize the warning display.

  As described above, in the conventional ignition device, since the resistance value of the resistor connected in series to the output short-circuit switch is set too small or too large, a problem occurs even if the resistor value is set too large. However, there is a problem that the adjustment becomes difficult and the manufacture is not easy.

  Further, when the output of the ignition power source is large, the resistance value of the resistor needs to be set to a very low value, so that the current flowing through the resistor becomes very large, and the resistor has an expensive rated power. It was necessary to use something.

  If a single resistor is used as the resistor connected in series to the output short-circuit switch, if the resistance cannot be reduced sufficiently, a large resistor with a large rated power should be used. There is a problem that the ignition device becomes large because it is necessary to connect a plurality of devices in parallel.

  In addition, in the conventional ignition device, it is necessary to set the resistance value of the resistor connected in series to the output short-circuit switch in accordance with the characteristics of the ignition power source to be combined. Cost reduction was not achieved by standardization.

  The object of the present invention is to eliminate the need for fine adjustment in accordance with the output of the ignition power supply and facilitate manufacturing, and to use a large resistor in the circuit for short-circuiting the output of the ignition power supply. It is an object of the present invention to provide a capacitor discharge type ignition device for an internal combustion engine which can reduce the size of the device by eliminating the above.

  Another object of the present invention is to provide a capacitor discharge type internal combustion engine ignition device capable of reducing the cost by standardizing a safety circuit.

The present invention provides an ignition coil, an exciter coil provided in a magnet generator driven by an internal combustion engine , an ignition capacitor charged to one polarity by the output of the exciter coil, and an ignition signal. A discharge switch for discharging the charge accumulated in the ignition capacitor through the primary coil of the ignition coil, an ignition signal supply means for supplying an ignition signal to the discharge switch at the ignition timing of the internal combustion engine, and an abnormality in the internal combustion engine An abnormality detection switch that performs a detection operation when an abnormality is detected, and a safety circuit that prevents the internal combustion engine from being ignited when the abnormality detection switch performs a detection operation, stops the internal combustion engine, and performs an alarm operation; An ignition device for a capacitor discharge internal combustion engine provided with

In the present invention, when the safety circuit is connected in parallel via a series circuit of a plurality of diodes between the output terminals of the exciter coil and is turned on, the output terminals of the exciter coil are connected in series with the plurality of diodes. An output short-circuit switch that short-circuits through the circuit and prevents charging of the ignition capacitor, and when the abnormality detection switch is not performing detection operation, the output short-circuit switch is kept off, and the abnormality detection switch performs detection operation. A switch control circuit that controls the output short-circuit switch according to the state of the abnormality detection switch so that the output short-circuit switch is turned on and kept on, and a resistor at both ends of a series circuit of a plurality of diodes a plurality of diodes when the switch output short consist coupled LEDs is turned on through And a warning means for emitting light and the warning operation by voltage generated at both ends of the series circuit of de (forward voltage drop of the diode) is applied.

As described above, the output short-circuit switch is connected between the output terminals of the exciter coil through a plurality of diodes connected in series, and the alarm means is driven by the voltage generated at both ends of the series circuit of the plurality of diodes. Then, the alarm means can be driven without causing a large loss as in the conventional ignition device in which a resistor is connected in series to the output short-circuit switch.

  Moreover, if comprised as mentioned above, since it is not necessary to take the structure which connects several resistors with big rated power in parallel, a safety circuit can be attached without making an ignition device large.

Further, when configured as described above, in consideration of the output characteristics of various exciter coils prepared for charging the ignition capacitor, the alarm means can be reliably driven regardless of which exciter coil is used. By setting the number of diodes connected in series to the output short-circuit switch, it is possible to standardize the safety circuit for various exciter coils .

  In a capacitor discharge type ignition device for an internal combustion engine, an exciter coil provided in a magnet generator driven by the internal combustion engine is used as an ignition power source, and one end of the ignition capacitor is connected to one end of the exciter coil through a rectifying element. In many cases, the ignition capacitor is charged by the half-wave output voltage of one polarity of the exciter coil.

In this case, the safety circuit is connected in series between the output thyristor with the anode connected to one end of the exciter coil and the cathode of the thyristor and the other end of the exciter coil with the cathode facing the other end of the exciter coil. A plurality of connected diodes, a thyristor trigger circuit that provides a trigger signal from the exciter coil side to the gate of the output short-circuit thyristor when the abnormality detection switch performs a detection operation, a gate of the output short-circuit thyristor, and an exciter coil A holding capacitor connected between the ends of the thyristor, a holding diode connected between the gate and cathode of the thyristor with the cathode facing the gate side of the thyristor, and a resistor connected to both ends of a series circuit of a plurality of diodes. output short-circuit thyristor consist emitting diode is turned on It can forward voltage generated at both ends of the series circuit of the plurality of diodes when it is to constitute a with a warning means for emitting light and the warning operation by being applied.

  With the above configuration, a voltage drop generated across the series circuit of the plurality of diodes while the output short-circuit thyristor is in the on state is sufficient for the holding capacitor to trigger the thyristor through the holding diode. Charges up to voltage. Thus, if a holding capacitor that is charged by the voltage across the series circuit of a plurality of diodes is provided, even if the trigger signal given through the thyristor trigger circuit is interrupted due to chattering of the abnormality detection switch, etc. Since the trigger voltage can be given to the output short-circuit thyristor by the voltage of the capacitor, every time the exciter coil generates a half-wave output voltage of one polarity, the output short-circuit thyristor is reliably turned on to prevent ignition operation The engine can be stopped reliably when an abnormality occurs.

As described above, according to the present invention, the output short-circuiting switch that short-circuits the output of the exciter coil in the event of an abnormality is connected between the output terminals of the exciter coil through the plurality of diodes connected in series. Because the alarm means is driven by the voltage generated at both ends of the series circuit, the alarm is generated without causing a large loss as in the conventional ignition device in which a resistor is connected in series to the output short-circuit switch. The means can be driven.

  Further, according to the present invention, since it is not necessary to adopt a configuration in which a plurality of resistors having large rated power are connected in parallel, a safety circuit can be attached to the ignition device without increasing the size of the ignition device.

Furthermore, according to the present invention, the number of diodes connected in series to the output short-circuit switch is appropriately set in consideration of the output characteristics of various exciter coils prepared for charging the ignition capacitor. Thus, there is an advantage that the safety circuit can be standardized for various exciter coils .

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The present invention can be applied regardless of the number of cylinders of the engine, but in the following description, an ignition device for igniting a single cylinder internal combustion engine will be taken as an example.
FIG. 1 shows the configuration of a preferred embodiment of the present invention. In FIG. 1, 1 is an ignition coil having a primary coil 1a and a secondary coil 1b that are grounded at one end, and 2 is a magnet power generation driven by an internal combustion engine. An exciter coil 4 provided in the machine 3 is an ignition capacitor having one end connected to one end 2 a of the exciter coil 2 through a capacitor charging diode (rectifier element) 5. In the illustrated example, the other end 2b of the exciter coil 2 is grounded, and the other end of the ignition capacitor 4 is connected to the other end (non-ground side terminal) of the primary coil 1a of the ignition coil. In this example, the exciter coil 2 constitutes an ignition power source.

  Reference numeral 6 denotes a thyristor as a discharge switch that conducts when an ignition signal is applied and discharges the electric charge accumulated in the ignition capacitor 4 through the primary coil 1a of the ignition coil. The thyristor 6 has its cathode on the ground side. Toward, it is connected between one end of the ignition capacitor 4 and the ground.

  A signal generator 7 serves as an ignition signal supply means for giving an ignition signal to the thyristor 6 at the ignition timing of the internal combustion engine. The signal generator 7 includes a signal coil 7a wound around an iron core having a magnetic pole portion facing a reluctator provided on a rotor of a magnet generator, and a known magnet provided with a permanent magnet magnetically coupled to the iron core. Thus, pulse signals having different polarities are induced in the signal coil 7a when the front end side edge and the rear end side edge in the rotation direction of the reluctator are detected. A signal Vs in the direction of the arrow shown in the figure induced in the signal coil 7a is given to the gate of the thyristor 6 as an ignition signal.

  In the illustrated example, a capacitor discharge type primary current control circuit 8 is configured by the ignition capacitor 4, the diode 5, and the thyristor 6, and the capacitor current discharge type ignition circuit is formed by the primary current control circuit 8 and the ignition coil 1. Is configured.

  In this ignition circuit, the ignition capacitor 4 is charged with the polarity shown in the figure by the half-wave output voltage of one polarity of the exciter coil 2 in the direction of the arrow shown in the drawing. When the ignition signal Vs is applied from the signal coil 7a to the gate of the thyristor 6 at the ignition timing of the internal combustion engine, the thyristor 6 is turned on, so that the electric charge accumulated in the ignition capacitor 4 is the primary coil of the thyristor 6 and the ignition coil. Discharge through 1a. This discharge causes a large change in magnetic flux in the iron core of the ignition coil, so that a high voltage for ignition is induced in the secondary coil 1b of the ignition coil. Since this high voltage is applied to the spark plug 9 attached to the cylinder of the engine, a spark discharge occurs in the spark plug 9 and the engine is ignited.

  Reference numeral 10 denotes an abnormality detection switch that performs a detection operation when an abnormality in the internal combustion engine is detected. In this embodiment, the abnormality detection switch detects an abnormality in the level of the lubricating oil level in the internal combustion engine. It is made up of. The illustrated abnormality detection switch 10 is in an off state when the level of lubricating oil in the engine exceeds a set value, and is in an on state when the level of lubricating oil is below a set value. Then, a detection operation for detecting that the level of the lubricating oil is abnormal is performed.

  11 is a safety circuit that prevents the internal combustion engine from being ignited when the abnormality detection switch 10 performs the detection operation, stops the internal combustion engine, and performs an alarm operation. The illustrated safety circuit includes the exciter coil 2. Between the cathode of the thyristor 12 and the other end (ground) 2b of the exciter coil in a state where the anode is connected to the one end 2a and the cathode is directed to the other end side (ground side) of the exciter coil 2. Trigger diodes from the exciter coil 2 side to the gate of the thyristor 12 when the abnormality detection switch 10 performs a detection operation with a plurality of (three in the illustrated example) drive voltage generating diodes D1 to D3 connected in series. A holding thyristor 13 connected between the thyristor trigger circuit 13 for supplying a signal, the gate of the output short-circuit thyristor 12 and the other end of the exciter coil 2. Connected to both ends of a series circuit of a capacitor 14, a holding diode 15 whose anode is connected between the gate and cathode of the thyristor 12 toward the cathode side of the thyristor 12, and a plurality of diodes D 1 to D 3 for output short circuit When the thyristor 12 is turned on, an alarm that is driven by a voltage generated at both ends of a series circuit of a plurality of diodes D1 to D3 (the sum of forward voltage drops of the diodes D1 to D3) and performs an alarm operation Means 16.

  The alarm means 16 shown comprises a light emitting diode LED, the cathode of the light emitting diode LED is grounded, and the anode is connected to the cathode of the output short-circuit thyristor 12 through a resistor 17 and a connector 18.

  The thyristor trigger circuit 13 includes a first trigger signal supply diode 20 having an anode connected to one end 2 a of the exciter coil 2 via a connector 19, and an anode connected to the cathode of the diode 20 through a resistor 21. A collector is connected to the anode of the second trigger signal supply diode 22 connected to the gate of the output short-circuit thyristor 12, and an emitter is connected to the other end 2 b of the exciter coil 2. NPN transistor 23, a resistor 24 connected between the cathode of first trigger signal supply diode 20 and the base of transistor 23, and a capacitor 25 connected between the base and emitter of transistor 23. ing.

  One end of the abnormality detection switch 10 is grounded, and the other end is connected to the base of the transistor 23 through the connector 26. The transistor 23 includes a diode 20 and a resistor 24 when the abnormality detection switch 10 is in an off state (no detection operation is performed) and the exciter coil 2 outputs a half-wave voltage of one polarity. A base current is applied through the thyristor 12 to turn it on, and a trigger signal applied from the exciter coil 2 to the thyristor 12 through the diode 20, the resistor 21, and the diode 22 is bypassed from the thyristor 12. When the abnormality detection switch 10 is turned on (when the level of the lubricating oil of the engine is abnormally lowered and the detection operation is performed), the transistor 23 is turned off, and a trigger signal is given to the output short-circuit thyristor 12. It is done.

  In the illustrated example, the first and second trigger signal supply diodes 20 and 22 and the resistor 21 output from the exciter coil 2 when the exciter coil 2 outputs a half-wave voltage of one polarity. A trigger signal supply circuit that supplies a trigger signal to the short-circuit thyristor 12 is configured, and a trigger signal supply control circuit is configured by the transistor 23, the resistor 25, and the capacitor 25. The trigger signal supply control circuit maintains an ON state when the abnormality detection switch 10 is not performing a detection operation, and triggers the thyristor 12 by bypassing the trigger signal supplied through the trigger signal supply circuit from the thyristor 12. The signal is prohibited from being applied, and when the abnormality detection switch 10 performs the detection operation, the signal is turned off to allow the trigger signal to be supplied to the thyristor 12.

  In the ignition device shown in FIG. 1, when the crankshaft of the internal combustion engine is rotated by the starter, the exciter coil 2 outputs an alternating voltage. When the remaining amount of the lubricating oil level of the internal combustion engine is greater than or equal to the allowable lower limit value and the oil level exceeds the set level, the abnormality detection switch 10 is in the OFF state, so the exciter coil 2 is in the direction indicated by the solid arrow in the figure. When a half-cycle voltage of one polarity is output, a base current is applied to the transistor 23 through the diode 20 and the resistor 24 to turn on the transistor, and the diode 20, the resistor 21, and the diode 22 are turned on from the exciter coil 2. The trigger signal applied to the gate of the thyristor 12 through is routed from the thyristor 12 through the transistor 23.

  Therefore, when the level of the lubricating oil exceeds the set level, the thyristor 12 cannot be turned on, and the safety circuit 11 has no influence on the output voltage of the exciter coil 2. Further, when the thyristor 12 is in the OFF state, no voltage is generated across the series circuit of the drive voltage generating diodes D1 to D3, so that the light emitting diode LED as the alarm means does not emit light.

  In this state, when the exciter coil 2 outputs a half-cycle voltage of one polarity in the direction of the solid line in the figure, the ignition capacitor 4 is charged to the polarity shown through the diode 5 and the primary coil 1a of the ignition coil. .

  When the signal coil 7a generates an ignition signal at the ignition timing of the internal combustion engine, the thyristor 6 is turned on and the electric charge accumulated in the ignition capacitor 4 is discharged through the primary coil 1a of the ignition coil, and the secondary coil 1b of the ignition coil. To induce a high voltage for ignition. Since this high voltage is applied to the spark plug 9, a spark discharge is generated in the spark plug 9, the engine is ignited, and the engine is started.

  When the remaining amount of lubricating oil in the engine falls below the allowable lower limit value and the oil level falls below the set level value, the abnormality detection switch 10 is turned on, so that the base emitter of the transistor 23 of the safety circuit 13 When the exciter coil 2 induces a half-cycle voltage of one polarity, the transistor 23 cannot conduct. Therefore, when the exciter coil 2 generates a half-cycle voltage of one polarity, a trigger signal is given to the thyristor 12 through the diode 20, the resistor 21, and the diode 22, and the thyristor becomes conductive.

  Thus, when the engine lubricating oil is insufficient and the oil level becomes lower than the set level, the exciter coil 2 generates a half-wave voltage of one polarity and at the same time the thyristor 12 of the safety circuit 10 is turned on. Therefore, the exciter coil 2 is short-circuited through the thyristor 12 and the diodes D1 to D3, and the ignition capacitor 4 is hardly charged. Therefore, the engine is no longer ignited and the engine is stopped. At this time, the voltage generated at both ends of the diodes D1 to D3 due to the current flowing through the thyristor 12 and the diodes D1 to D3 is applied to the light emitting diode LED, so that the light emitting diode emits light and the oil level drops below the set level. Generates an alarm for that.

  As described above, a plurality of diodes are connected in series to the output short-circuiting switch (thyristor 12 in the above example) that short-circuits the output of the ignition power supply when an abnormality occurs, and is generated at both ends of the series circuit of the plurality of diodes. When the alarm means is driven by the voltage, as in the conventional ignition device that drives the alarm means by the voltage across the resistor connected in series to the output short-circuit switch, without causing a large loss, The alarm means can be driven.

  In the present invention, it is not necessary to connect a plurality of resistors having a large rated power in parallel. Therefore, a safety circuit can be attached to the ignition device without making the ignition device large.

  Furthermore, according to the present invention, by appropriately setting the number of diodes connected in series to the output short-circuit switch, for example, among various ignition power supplies prepared for charging the ignition capacitor, the output is Even when the lowest ignition power supply is used, the diode connected in series with the output short-circuit switch can be used to generate a voltage sufficient to drive the alarm means across the series circuit of the plurality of diodes. By setting the number, no matter which ignition power source is used, the output of the ignition power source can be short-circuited and the alarm means can be reliably driven. Can do.

  In the above embodiment, the signal generator 7 constitutes the ignition signal supply means, and the signal generated from the signal generator 7 at the ignition timing of the internal combustion engine is given to the discharge switch as an ignition signal. Of course, the ignition signal supply means may be configured so that the ignition timing is calculated based on the engine rotation information obtained from the generator 7 and the ignition signal is supplied to the thyristor 6 at the calculated ignition timing.

It is the circuit diagram which showed the structure of embodiment of this invention.

1 Ignition Coil 2 Exciter Coil 4 Ignition Capacitor 5 Rectifier 6 Thyristor (Discharge Switch)
7 Signal generator 10 Abnormality detection switch 11 Safety circuit 12 Output short-circuit switch 13 Thyristor trigger circuit

Claims (2)

An ignition coil, an exciter coil provided in a magnet generator driven by an internal combustion engine , an ignition capacitor charged to one polarity by the output of the exciter coil , and a conduction when an ignition signal is given A discharge switch for discharging the charge accumulated in the ignition capacitor through a primary coil of the ignition coil, an ignition signal supply means for supplying an ignition signal to the discharge switch at an ignition timing of the internal combustion engine, and an abnormality in the internal combustion engine An abnormality detection switch that performs a detection operation when detecting an abnormality, and a safety that performs an alarm operation while preventing the internal combustion engine from being ignited when the abnormality detection switch performs a detection operation and stopping the internal combustion engine. In an ignition device for a capacitor discharge internal combustion engine comprising a circuit,
The safety circuit is connected between the output terminals of the exciter coil in parallel via a series circuit of a plurality of diodes and is turned on to pass between the output terminals of the exciter coil through the series circuit of the plurality of diodes. An output short-circuit switch that short-circuits and prevents charging of the ignition capacitor; and when the abnormality detection switch is not performing a detection operation, the output short-circuit switch is kept off, and the abnormality detection switch performs a detection operation. a switch control circuit for controlling the switch the output short-circuit in accordance with the output short-circuiting switch the state of the abnormality detecting switch so as to retain its oN state in the on state when performing the series of the plurality of diodes switch the output short consist coupled LEDs through a resistor across the on state of the circuit It is and wherein the plurality of capacitor discharge ignition device forward voltage Naru emits light by being applied to and a warning means for performing the alarm operation that occurs across the series circuit of the diode when being. An ignition coil, an exciter coil provided in a magnet generator driven by an internal combustion engine, and one end of the exciter coil connected to one end through a rectifier and charged by the half-wave output voltage of one polarity of the exciter coil. An ignition capacitor, a discharge switch that conducts when the ignition signal is applied and discharges the electric charge accumulated in the ignition capacitor through a primary coil of the ignition coil, and the discharge capacitor at the ignition timing of the internal combustion engine Ignition signal supply means for providing an ignition signal to the switch, an abnormality detection switch that performs a detection operation when an abnormality of the internal combustion engine is detected, and the internal combustion engine is ignited when the abnormality detection switch performs a detection operation For a capacitor discharge type internal combustion engine provided with a safety circuit for stopping the internal combustion engine and preventing an alarm In fire apparatus,
The safety circuit includes a thyristor having an anode connected to the one end of the exciter coil, and a series connection between the cathode of the thyristor and the other end of the exciter coil with the cathode facing the other end of the exciter coil. A plurality of diodes connected to the thyristor, a thyristor trigger circuit for providing a trigger signal from the exciter coil side to the gate of the thyristor when the abnormality detection switch performs a detection operation, a gate of the thyristor, and other than the exciter coil A holding capacitor connected between one end and a holding diode connected between the gate cathode of the thyristor with a cathode facing the gate side of the thyristor;
A forward voltage generated at both ends of the series circuit of the plurality of diodes is applied when the thyristor is turned on when the thyristor is turned on through a resistor connected to both ends of the series circuit of the plurality of diodes. An alarm means for emitting the light and performing the alarm operation,
An ignition device for a capacitor discharge internal combustion engine.

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