JPH0444853Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is used by assembling it into a non-contact ignition device for an internal combustion engine for safety, and when the internal combustion engine rotates abnormally. This invention relates to a stop circuit as a safety device that automatically stops the operation of an internal combustion engine by sensing a voltage value.

[Conventional technology]

Among non-contact ignition devices for internal combustion engines that use semiconductor switching elements, external trigger type ignition circuits achieve the triggering of the main switching element of the ignition circuit by a trigger voltage generated by a dedicated trigger coil. As a safety device in case the rotational speed of the internal combustion engine becomes abnormally high, if the rotational speed of the internal combustion engine exceeds a certain value, the ignition device will forcibly stop the ignition operation, thereby stopping the operation of the internal combustion engine. A stop circuit is used to

This stop circuit utilizes the circuit configuration of an external trigger type ignition circuit to detect when the rotational speed of the internal combustion engine has exceeded a set constant speed. The inserted switching element is brought into conduction to short-circuit both terminals of the trigger coil, thereby making it impossible to generate a trigger voltage in the trigger coil, thereby making it impossible to perform an ignition operation.

In the case of the ignition operation circuit in this external trigger type ignition circuit, when the output of the trigger coil is small, the short circuit current generated between both terminals of the trigger coil is also small, so the switching element for short circuit is also small. Although the rating is fine, the trigger coil mechanism part of an external trigger type ignition system uses the flywheel of the main power generating mechanism of the ignition system as it is in order to keep its configuration as simple as possible. Generally, the output of this trigger coil is large.

The large output in this trigger coil is large enough to trigger the main switching element of the ignition circuit, so there is no problem with normal ignition operation, and smooth ignition operation can be obtained.

[Problem that the invention attempts to solve]

However, as the trigger coil becomes larger in size, the impedance of this trigger coil becomes lower and the trigger current also becomes larger. Accordingly, the rating of the switch element used to short-circuit both terminals of this trigger coil also becomes larger. There is a need.

In this way, if the rating of the switch element, which is installed to generate a trigger signal to the main switching element of the ignition circuit by shorting both terminals of the trigger coil, increases, the amount of power flowing to the switch element when the trigger coil is short-circuited increases. Due to the short circuit current, the amount of voltage drop across this switching element becomes large, and this large voltage drop value is applied to the control terminal of the main switching element of the ignition circuit, causing the main switching element to There is no guarantee that a reliable cut-off operation of the switching element can be obtained. Therefore, the voltage drop value of the switch element when the trigger coil is short-circuited is
It is necessary to configure the trigger circuit so that the voltage is not applied directly to the control terminal of the main switching element of the ignition circuit, and the circuit configuration of the trigger circuit is accordingly complicated.

In addition, this switch element turns on when the rotational speed of the internal combustion engine exceeds a set value.
This must be achieved at the same time as the normal voltage is generated in the trigger coil, which complicates the circuit configuration.

In short, the stop circuit in a conventional external trigger type ignition system is to short-circuit both terminals of the trigger coil using a short-circuit switch element while the control terminal of the main switching element of the ignition circuit is connected to the trigger coil. is used as the means to stop the ignition operation, so even if both terminals of the trigger coil are short-circuited by the switching element, the trigger coil and the control terminal of the main switching element are completely electrically disconnected. Therefore, depending on the electrical characteristics exhibited by the combination of the trigger coil and the short-circuiting switching element, the main switching element may be electrically affected.

The present invention was devised to solve the problems and inconveniences of the conventional examples described above, and is designed to prevent the triggering of the main switching element of the ignition circuit when the rotational speed of the internal combustion engine exceeds a set value. Therefore, the technical problem is to forcibly break the connection between the trigger coil and the control terminal of the main switching element.

[Means for solving problems]

Hereinafter, a stop circuit according to the present invention will be explained with reference to the drawings showing an embodiment of the present invention.

The means of the present invention is that the stop circuit 7 is assembled into an external trigger type non-contact ignition device, that a high resistance resistor 17 for triggering is inserted between the anode terminal and the control terminal, and that the trigger coil 6 is connected to the stop circuit 7. The switch element 10 is inserted and connected between the positive side terminal and the control terminal of the switching element 2 which is the main switching element of the ignition device, and the control terminal of the switch element 10 and the negative side terminal of the trigger coil 6 are connected. It has a control element 11 that is inserted and connected between the two and controls the conduction of the switch element 10, it has a capacitor 12 that charges the reverse voltage of a certain value or more generated in the trigger coil 6, and the positive side electrode of this capacitor 12. is connected to the control terminal of the control element 11.

[Effect]

When the internal combustion engine is being driven at a normal rotational speed, when a forward voltage is induced in the trigger coil 6, this voltage causes a trigger current to flow into the control terminal of the switch element 10 through the resistor 17.
The switch element 10 is turned on and the trigger signal from the trigger coil 6 is applied to the control terminal of the main switching element 2 of the ignition circuit, so that the ignition circuit performs a predetermined ignition operation.

From this normal operating state, due to some reason,
When the rotational speed of the internal combustion engine exceeds a preset value and enters an overspeed state, the reverse voltage of the trigger coil 6, which increases the induced voltage in proportion to the rotational speed of the internal combustion engine, also exceeds a preset constant value. A part of the reverse voltage generated in the trigger coil 6 is charged to the capacitor 12.

The anode of the capacitor 12 charged with this reverse voltage is connected to the control terminal of the control element 11 inserted and connected between the control terminal of the switch element 10 and the negative terminal of the trigger coil 6. is triggered by the reverse voltage charged in this capacitor 12.

Control terminal of switch element 10 and trigger coil 6
Control element 1 inserted between the negative terminal of
1 is in the triggered state, when a forward voltage is induced in the trigger coil 6, both terminals of the trigger coil 6 are short-circuited by the series circuit of the resistor 17 and the control element 11, The trigger current which should flow into the control terminal of the switch element 10 through the resistor 17 is bypassed by the control element 11, so that the switch element 10 cannot be turned on and remains in the cut-off state.

Therefore, the trigger signal that should be applied from the trigger coil 6 to the control terminal of the switching element 2 through the switching element 10 is not applied to the control terminal of the switching element 2, and the trigger signal is not applied to the control terminal of the switching element 2.
will not be able to turn on and the igniter will cease its ignition operation.

When the circuit of the present invention is activated, the trigger coil 6
A high-resistance resistor 17 and a control element 11 are connected between both terminals of
As a result, a high voltage drop occurs across this resistor 17 due to the short-circuit current. However, since the switching element 10 is in the cut-off state, the voltage value of this resistor 17 is used to control the switching element 2. There is no electrical influence on the terminals.

That is, the present invention enables the ignition operation of the ignition device to
Since its basic configuration is to achieve this by cutting off the electrical connection between the trigger coil 6 and the switching element 2, electrical changes on the trigger coil 6 side will not affect the switching element 2 at all. Therefore, it is possible to achieve and maintain a reliable turn-off state of the switching element 2.

In addition, the trigger signal to the control terminal of the switching element 2 is not only cut off directly between the trigger coil 6 and the control terminal of the switching element 2 by the switch element 10, but also by the connection between the resistor 17 and the control element 11. Since the structure is such that both terminals of the trigger coil 6 are short-circuited, the switch element 10
A large cut-off voltage is not applied to the switch element 10, and therefore a small and low-power switch element 10 can be used.

Furthermore, since the trigger of the control element 11 that achieves and maintains the turn-off of the switching element 10 utilizes the reverse voltage generated prior to the forward voltage in the trigger coil 6 for triggering the switching element 2, it is possible to properly stop the ignition operation. You can always get the timing reliably and easily.

〔Example〕

The illustrated embodiment shows an example implemented in an external trigger type capacitive discharge type non-contact ignition device. coil 4
The capacitor 3 is charged through the primary winding of
Switching element 2 turned on by a trigger signal from trigger coil 6 after a certain timing
The electric charge stored in the capacitor 3 is rapidly discharged to the primary winding of the ignition coil 4, and this discharge induces a high voltage in the secondary winding of the ignition coil 4, and the plug 5 connected to the secondary winding is A spark discharge occurs and ignition is achieved.

In FIG. 1, a differentiating circuit 8 inserted between the control terminal of the switching element 2 and the trigger coil 6 ensures and stabilizes the turn-on operation of the switching element 2 by the trigger signal from the trigger coil 6. This is an auxiliary circuit to achieve this.

The stop circuit 7 according to the present invention is inserted and connected between the trigger coil 6 and the control terminal of the switching element 2. As shown in FIG.
A thyristor is used as 1.

A charging circuit that charges the reverse voltage generated in the trigger coil 6 to the capacitor 12 is connected to the trigger coil 6.
A resistor 16 for current limiting, a diode 15 in a reverse orientation, a Zener diode 14 in a forward orientation, a capacitor 12 for charging reverse voltage, and a diode 13 in a reverse orientation.
It is constructed by connecting in series.

In addition, in FIG. 2, capacitors 26 and 27 are noise prevention capacitors, and diode 2
5 and resistor 19 are for stabilizing the operation of control element 11, resistors 20 and 21 are for adjusting charging voltage in capacitor 12,
The Zener diode 22 is for discharging the excess charge voltage in the capacitor 12, the resistor 24 and thermistor 23 are for temperature control and temperature compensation, and the diode 18 connected to the control terminal of the switch element 10 is for discharging the overcharge voltage in the capacitor 12. This is to ensure that the short circuit current flows to the control element 11 side.

In the embodiment shown in FIG. 2, when the reverse voltage generated in the trigger coil 6 exceeds the voltage value set by the Zener diode 14 due to the rotational speed of the internal combustion engine exceeding the set rotational speed, this The Zener diode 14 breaks down and the capacitor 12 is charged with a reverse voltage.

The electric charge charged in the capacitor 12 is discharged through the diode 25, the control terminal of the control element 11, the cathode terminal of the control terminal 11, and the resistor 20, thereby triggering the control element 11. This control element 1
Since the trigger caused by the discharge of the capacitor 12 of No. 1 is sustained during the discharge period of the capacitor 12, the control can be performed by setting the discharge period of the capacitor 12 to continue throughout the period in which the forward voltage is generated in the trigger coil 6. The turn-on of element 11 is sustained, so that switch element 10 is cut off and prevents ignition operation.

[Effect of idea]

As is clear from the above explanation, the stop circuit according to the present invention cuts off the connection of the trigger coil to the control terminal for preventing switching, so that the influence of electrical fluctuations on the trigger coil side at the time of cut-off and during the cut-off period is reduced to the switching element. Therefore, a reliable and stable turn-off state of the switching element can be achieved and maintained.
Also, instead of leaving the trigger coil disconnected from the switching element in an open state, it is configured to short-circuit both terminals of the trigger coil with a high resistance, so the switching element and the trigger coil are disconnected. The switch element is not required to have a high withstand voltage performance, and it is possible to use a switch element with a lower rating, which in turn allows the electrical components that make up the circuit to have a lower rating. Furthermore, since it operates using the reverse voltage that is generated prior to the generation of the forward voltage of the trigger coil, it has many excellent effects such as being able to easily and appropriately determine the timing to stop the ignition operation of the ignition circuit. It is something that demonstrates the.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of an electric circuit of an external trigger type ignition device to which the circuit of the present invention is assembled. FIG. 2 is an electrical circuit diagram showing one embodiment of the circuit of the present invention. Explanation of symbols, 1... Generator coil, 2... Switching element, 3... Main capacitor, 4... Ignition coil, 5... Plug, 6... Trigger coil, 7...
... Stop circuit, 10 ... Switch element, 11 ... Control element, 12 ... Capacitor, 17 ... Resistor.

Claims (1)

[Scope of utility model registration request] The stop circuit 7 is assembled into an external trigger type non-contact ignition device, and a high resistance resistor 17 for triggering is inserted between the anode terminal and the control terminal, and the positive terminal of the trigger coil 6 and the ignition device are connected to each other. A switch element 10 is inserted and connected between the control terminal of the switching element 2 and a negative terminal of the trigger coil 6. and a capacitor 12 that charges the reverse voltage of a certain value or more generated in the trigger coil 6, and the positive electrode of the capacitor 12 is connected to the control terminal of the control element 11. A stop circuit for a non-contact ignition device.