JP6463917B2 - Non-contact ignition control device for internal combustion engine - Google Patents

Description

The present invention relates to a contactless ignition control device for an internal combustion engine for guiding the internal combustion engine to misfire control by operating a stop switch during operation of the internal combustion engine.

Conventionally, based on the induced electromotive force induced in synchronization with the rotation of the internal combustion engine, a spark is generated at the spark plug at a predetermined control timing to continue the operation of the internal combustion engine. A contactless ignition control device for an internal combustion engine that leads to misfire control and automatically stops the internal combustion engine has been proposed (see, for example, cited document 1).

FIG. 5 is a block diagram conceptually showing such a contactless ignition control device for an internal combustion engine. In FIG. 5, a CDI type ignition control circuit 32 and an ignition circuit 33 are sequentially connected to the power generation coil 31, and a stop switch 34 is connected to the power generation coil 31 in parallel.

The stop switch 34 is kept open during operation of the internal combustion engine, and is closed by human operation when the internal combustion engine is misfired and stopped. When the stop switch 34 is closed, both terminals of the power generation coil 31 are short-circuited, power supply to the ignition control circuit 32 and the like is stopped, and ignition of the internal combustion engine is also stopped.

By the way, the internal combustion engine is widely used as a power source for sprayers, pesticide spreaders, mowers, etc., and the device can be stopped by misfire control of the internal combustion engine by an ignition control circuit when the stop switch 34 is closed. Yes. On the other hand, in the device such as the sprayer, the stop switch 34 is provided in the vicinity of the end of the support member, for example, in the vicinity of the end of the support member, which can be operated at a distance from the power generation coil 31 together with the pump, blower, rotary blade, etc. It is common.

In order to reduce the size and unit of a contactless ignition device for an internal combustion engine, the power generation coil 31, the ignition control circuit 32, and the like may be resin-molded. The resin-molded power generation coil 31 and the ignition control circuit 32 are housed in a plastic casing together with a part or all of the main body of the sprayer or the like.

However, the stop switch 34 and part of the wiring connecting the stop switch 34 are
In order to allow switch operation, it is installed outside the casing. For this reason, at least the terminals (generally connector terminals) of the stop switch 34 are exposed to the outside.

Further, in the conventional contactless ignition control device for an internal combustion engine as described above, the stop switch 34 is in an open state during the operation of the internal combustion engine such as the sprayer and the friction with the air sent out by the blower or the like. As a result, static electricity accumulated on the casing surface may jump into the terminal of the stop switch 34 and wiring connected to the terminal. In this case,
The static electricity becomes a surge current and flows to the electronic components in the power generation coil 31 and the ignition control circuit 32, thereby destroying the insulation or causing malfunction.

On the other hand, a contactless ignition control circuit in which a surge absorbing element 35 as shown by a chain line in FIG. 5 is connected in parallel to the stop switch 34 is provided. According to this configuration, even if the static electricity accumulated on the casing surface, external electrostatic noise, or electromagnetic noise jumps into the terminal or wiring of the stop switch, the surge absorbing element 35 can generate the power generation coil 31 or the ignition control circuit. By absorbing (blocking) the entry of a surge current to 32 etc., it is possible to prevent dielectric breakdown and malfunction of electronic components.

JP 2000-240549 A

However, in the conventional non-contact ignition control device for an internal combustion engine as described above, the stop switch 34 is used to prevent breakdown or malfunction of electronic components in the ignition control circuit.
It is necessary to connect a surge absorbing element 35 for high voltage, that is, a large withstand voltage value, in parallel,
For this reason, the size of the surge absorbing element 35 on a circuit board or the like on which an electronic circuit is mounted is increased, and there is a problem in that the ignition control circuit and the contactless ignition control device as a whole are reduced in size and cost.

The present invention solves the conventional problems as described above, and the static electricity accumulated on the casing surface covering the electronic parts such as the contactless ignition control circuit jumps into the terminal or wiring of the stop switch. In addition, by using a small-sized surge absorbing element having a small withstand voltage value, it is possible to prevent the surge current from entering the ignition control circuit or the like based on the static electricity. An object of the present invention is to provide a contactless ignition control device for an internal combustion engine that can reliably avoid the above.

To achieve the above object, a non-contact ignition control device for an internal combustion engine according to the present invention includes a power generation coil for inducing a voltage in synchronization with the rotation of the internal combustion engine, and a power generation coil in synchronization with the rotation of the internal combustion engine. A trigger coil that induces a voltage lower than the induced voltage, an ignition charge / discharge capacitor that charges the induced voltage of the power generation coil, and an ignition coil that discharges the charge charged in the ignition charge / discharge capacitor when the ignition coil is turned on A first thyristor that supplies power to the power generation coil, a trigger control capacitor that is connected to each of the power generation coil and the trigger coil via a diode and charges part of the induced voltage of the power generation coil and the trigger coil, and the trigger control When the charging voltage of the capacitor reaches a set level, it is turned on, and the induced voltage of the part of the generator coil is bypassed in the ground direction. To prevent the first thyristor from triggering, allowing the charging / discharging capacitor for ignition to be charged, and turning on the first thyristor at the set potential of the induced voltage of the subsequent trigger coil, A second thyristor that drives the ignition circuit by discharging the charge of the ignition charge / discharge capacitor and the trigger control capacitor are connected in parallel, and the trigger control capacitor is short-circuited by an ON operation, and the first 2
By turning off the thyristor, the trigger current can be supplied to the first thyristor to turn it on, and the stop switch for short-circuiting the power generation coil and the stop switch are connected in parallel. In the open state, a surge current that tends to flow to the ignition control circuit based on static electricity accumulated on the plastic casing surface that encloses the ignition control circuit composed of the power generation coil, the trigger coil, the first thyristor, and the second thyristor And a surge absorbing element for absorbing.

With this configuration, when the internal combustion engine is in an open state in which the stop switch is open, static electricity charged on the casing surface jumps into the terminal of the stop switch and the wiring connecting the terminal and each electronic component of the ignition control circuit. However, the surge current based on the static electricity can be quickly dropped to the ground without flowing to the electronic component of the ignition control circuit on the low voltage circuit side. For this reason, it is possible to reliably avoid dielectric breakdown and malfunction of electronic components while using a low-voltage, small and low-cost surge absorbing element.

According to the present invention, even when static electricity accumulated on the surface of the main casing of a sprayer or the like jumps into the terminal of the stop switch or the wiring connected to the stop switch during operation of the internal combustion engine, By using the surge absorbing element, it is possible to prevent the surge current based on the static electricity from entering the electronic component of the ignition control circuit, and to reliably prevent dielectric breakdown and malfunction of the electronic component at low cost.

1 is a partially cutaway front view showing a rotor and a core constituting a contactless ignition control device for an internal combustion engine according to an embodiment of the present invention. It is a circuit diagram showing a non-contact ignition control device of an internal combustion engine according to an embodiment of the present invention. 3 is a timing chart showing voltage waveforms at various parts of the circuit shown in FIG. 2. It is a timing chart which shows the charge waveform of the capacitor for charging / discharging at the time of ON of a stop switch. It is a block diagram which shows notionally the conventional non-contact ignition control apparatus of an internal combustion engine.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an arrangement relationship between a power generation coil 1 and a trigger coil 2 constituting a contactless ignition device for an internal combustion engine in the present invention with respect to a rotor 3. In the figure, the rotor 3 is formed by embedding a pair of magnetic poles 6 and 7 so as to sandwich a magnet 5 in a nonmagnetic material 4 such as aluminum. The magnetic poles 6 and 7 are partially exposed on the outer peripheral surface of the rotor 3 as shown in the figure, and can be opposed to the end surfaces of the legs 8a and 8b of the U-shaped core 8 during the rotation of the rotor 3. Has been.

The power generating coil 1 and the trigger coil 2 are wound around the legs 8a and 8b, respectively. The opposing surfaces of the legs 8a and 8b to the rotor 3 are formed in an arc shape so that the distance from the rotor 3 is kept constant.

Here, the power generation coil 1 is configured to induce a high voltage because it is necessary to charge the ignition charge / discharge capacitor 10 with a large amount of ignition energy. On the other hand, the trigger coil 2 is configured to induce a low-level control voltage in order to instantaneously discharge the ignition charge / discharge capacitor 10. Therefore, the withstand voltage of the electronic components of the ignition control circuit centered on the trigger coil 2 can be kept low.

FIG. 2 is a circuit diagram showing a contactless ignition device for an internal combustion engine according to the present invention. In the figure, a power generation coil 1 includes a diode 9, an ignition charge / discharge capacitor 10, and an ignition coil 1.
1 primary coils 11a are connected in series, and these constitute a charging circuit for charging the ignition charge / discharge capacitor 10 with a positive voltage induced by the power generation coil 1.

Further, the ignition charge / discharge capacitor 10 is connected in series with the anode / cathode of the first thyristor 12 as the first switching element and the primary coil 11a of the ignition coil 11, and these are charged by the charge / discharge capacitor 10 for ignition. A discharge circuit for discharging electric charges is formed. The discharge circuit is activated when the first thyristor 12 is triggered to conduct,
The ignition charge / discharge capacitor 10 functions to discharge the charge to the ignition coil 11.

A spark plug 13 is connected to the secondary coil 11 b of the ignition coil 11. An LC oscillation diode 14 on the primary side of the ignition coil 11 is connected between the anode and cathode of the first thyristor 12. Further, a resistor 15, a diode 16 and a resistor 17 are connected in series to the power generation coil 1, and a resistor 18 and the resistor 17 are connected in series to the trigger coil 2. A connection point between the diode 16 and the resistor 17 and a connection point between the resistor 18 and the resistor 17 are connected to the gate of the first thyristor 12.

Further, the generator coil 1 includes a diode 19, a resistor 20, and a trigger control capacitor 2.
1 is connected in series, and a resistor 22, a diode 23, and the trigger control capacitor 21 are connected in series to the trigger coil 2. In addition, a resistor 28 and a diode 29 are connected in series to the power generating coil 1.

A stop switch 24 and a Zener diode or avalanche diode (bidirectional breakdown diode) as a surge absorbing element, here an avalanche diode 25 are connected in parallel to the trigger control capacitor 21. Further, a second thyristor 2 as a second switching element is provided between the connection point between the resistor 15 and the diode 16 and the ground.
6, and the gate of the second thyristor 26 is connected to a connection point between the resistor 20 and the trigger control capacitor 21 via a resistor 27.

Next, the operation of the non-contact ignition control device for the internal combustion engine will be described. First, when the internal combustion engine is operated and the rotor 3 rotates in the direction of arrow A in FIG. 1, the power generation coil 1 and the trigger coil 2 on the core 8 facing the rotor 3 are connected to FIGS. 3A and 3B. Each voltage of the waveform shown in FIG. Of the induced voltage of the power generation coil 1, the positive induced voltage is applied to the primary coil 11 a of the ignition coil 11 via the diode 9 and the charging / discharging capacitor 10 for ignition, and charges to the charging / discharging capacitor 10 for ignition. Is charged. The charging voltage waveform due to the positive induced voltage of the generator coil 1 is as shown in FIG.

On the other hand, among the induced voltages of the trigger coil 2, the positive induced voltage rises a predetermined period earlier than the rising of the positive induced voltage of the power generation coil 1. A part of the induced voltage of the trigger coil 2 and the induced voltage of the power generating coil 1 is charged in the trigger control capacitor 21 through the series circuit of the diode 19 and the resistor 20 and the series circuit of the resistor 22 and the diode 23, respectively. . When the potential across the trigger control capacitor 21 reaches a set level due to this charging, the second thyristor 26 is turned on (turned on) by a gate trigger.

Therefore, the positive induced voltage of the generator coil 1 is bypassed to the ground through the resistor 15 and the anode / cathode of the second thyristor 26, the gate potential of the first thyristor 12 is lowered, and the first thyristor 12 Turns off (turns off). For this reason, the generator coil 1
The above-described charging operation is performed in which the positive induced voltage is charged in the ignition charge / discharge capacitor 10. Then, a positive voltage is induced in the trigger coil 2 following the charging of the ignition charging / discharging capacitor 10, and when this induced voltage reaches a predetermined trigger level (TL) of the second thyristor 26, the first The thyristor 12 is turned on.

For this reason, the electric charge charged in the charging / discharging capacitor 10 as described above is applied to the primary coil 11a of the ignition coil 11 through the first thyristor 12, and the high voltage induced in the secondary coil 11b is a spark plug. 13 is applied. Thereby, the air-fuel mixture in the combustion chamber in the internal combustion engine is ignited. Then, by repeating the control operation by the thyristors 12 and 26, it is possible to start the internal combustion engine and subsequently increase the rotational speed.

On the other hand, in the operation of the contactless ignition device, the stop switch 24 is maintained in the off state. Therefore, when the operation of a sprayer or the like having an internal combustion engine is rapidly stopped, the stop switch 24 is turned on. As a result, the stop switch 24 short-circuits the trigger control capacitor 21, and charging to the trigger control capacitor 21 becomes impossible, and the first level of the positive induced voltage from the power generation coil 1 flowing through the resistor 15 becomes a predetermined level. One thyristor 12 is immediately triggered and turned on, and the generator coil 1 is short-circuited. As a result, charging from the power generating coil 1 to the charging / discharging capacitor is stopped as shown in FIGS. 4A and 4B, and the internal combustion engine falls into a misfire state and stops rotating.

The stop switch 24 is attached to the end of an indicator member away from a rotary blade or blower such as a chain saw or a sprayer in order to enable the above-described hand operation, and the power generation coil 1 which is resin-molded The trigger coil 2 and the ignition control circuit are provided outside the casing. For this reason, the static electricity accumulated on the casing surface jumps into the stop switch 24 and a part of the wiring connected to the stop switch 24 as described above.

In the above case, the static electricity becomes a surge current and tends to flow into the power generation coil 1 and the electronic components in the ignition control circuit. The avalanche diode 25 connected in parallel to the stop switch 24 has the surge current. Will be absorbed. For this reason, it is possible to reliably avoid dielectric breakdown and malfunction of the electronic component due to the surge current.

In the present invention, the stop switch 24 is installed in an ignition control circuit that operates using a relatively low voltage induced by the trigger coil 2 as a power source. For this reason, the surge current riding on the current flowing through the stop switch 24 and the wiring connected thereto is also at a relatively low level, and it is possible to use a surge absorbing element that absorbs the surge current with a low withstand voltage. become.

Therefore, as a surge absorbing element such as a zener diode or avalanche diode 25 having a low withstand voltage, a conventional one that is much smaller and more versatile than an element connected in parallel to the generator coil 1 is used. In addition to being easy to mount on the ignition control circuit board, the entire apparatus can be downsized.

As described above, the contactless ignition control apparatus for an internal combustion engine according to the present embodiment shorts the trigger control capacitor 21 by turning on the stop switch 24 connected in parallel to the trigger control capacitor 21. Thus, the second thyristor 26 is turned off, thereby enabling the supply of the trigger current to the first thyristor 12, thereby short-circuiting the generator coil 1, and the surge absorbing element 25 connected in parallel to the stop switch 24 In the open state of the stop switch 24, the ignition control circuit is connected to the ignition control circuit based on static electricity accumulated on the surface of the plastic casing that encloses the ignition control circuit including the power generation coil 1, the trigger coil 2, the first thyristor 12, and the second thyristor 26. It is configured to absorb the surge current that is about to flow.

Thereby, in the operating state of the internal combustion engine in which the stop switch 24 is in the open state, static electricity charged on the casing surface becomes a surge (pulse-like high level noise) current as a terminal of the stop switch 24, and this terminal and the ignition control circuit. Even if you jump into the wiring that connects
This surge current can be quickly dropped to the ground without flowing to the electronic components of the ignition control circuit on the low voltage circuit side. For this reason, it is possible to reliably avoid dielectric breakdown and malfunction of electronic components while using a low-voltage, small and low-cost Zener diode 25.

The non-contact ignition control device for an internal combustion engine of the present invention is small in size and withstand voltage even when static electricity accumulated on the casing surface covering the electronic components of the non-contact ignition control circuit jumps into the terminal or wiring of the stop switch. By using a surge absorbing element having a small value, it is possible to prevent the surge current from entering the ignition control circuit or the like based on the static electricity, and to reliably avoid dielectric breakdown of the electronic component or malfunction of the circuit due to the surge current. It is useful for a non-contact ignition control device for guiding an internal combustion engine to misfire control by operating a stop switch.

DESCRIPTION OF SYMBOLS 1 Generating coil 2 Trigger coil 10 Charging / discharging capacitor | condenser 11 Ignition coil 12 1st thyristor (1st switching element)
13 Spark plug 21 Capacitor for trigger control 24 Stop switch 25 Avalanche diode (surge absorption element)
26 Second thyristor (second switching element)

Claims (1)

A power generation coil that induces a voltage in synchronization with the rotation of the internal combustion engine, a trigger coil that induces a voltage lower than the voltage induced by the power generation coil in synchronization with the rotation of the internal combustion engine, and an induced voltage of the power generation coil An ignition charge / discharge capacitor for charging the ignition charge / discharge capacitor, and a first thyristor that discharges the charge charged in the ignition charge / discharge capacitor when it is turned on and supplies the ignition coil to the ignition coil;
A trigger control capacitor connected to each of the power generation coil and the trigger coil via a diode and charging a part of the induced voltage of the power generation coil and the trigger coil;
When the charge voltage of the capacitor for trigger control reaches a set level, it is turned on, the trigger of the first thyristor is prevented by bypassing the part of the induced voltage of the power generation coil in the ground direction, and the ignition The charging / discharging capacitor can be charged, and the first thyristor is turned on at the set potential of the induced voltage of the subsequent trigger coil to discharge the charging charge of the ignition charging / discharging capacitor, thereby driving the ignition circuit. A second thyristor to be connected in parallel to the trigger control capacitor, and the trigger control capacitor is short-circuited by an ON operation to turn off the second thyristor, thereby triggering the first thyristor. A stop switch that enables current supply and turns it on, and short-circuits the generator coil, and a parallel connection to the stop switch In the open state of the stop switch, flow to the ignition control circuit based on static electricity accumulated on the surface of the plastic casing enclosing the ignition control circuit composed of the power generation coil, the trigger coil, the first thyristor and the second thyristor. A non-contact ignition device for an internal combustion engine, comprising: a surge absorbing element for absorbing the surge current.

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