JPH0346227Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an ignition device for igniting an internal combustion engine, and in particular, the invention relates to an ignition device for igniting an internal combustion engine.
This invention relates to a capacitor discharge type internal combustion engine ignition device that induces a high voltage for ignition in a secondary coil.

Prior Art In a capacitor discharge type ignition system for an internal combustion engine, in order to prevent the charging voltage of the capacitor from becoming excessive when the engine is running at high speed, an exciter coil is used to charge the capacitor, as shown in Utility Model Application No. 52-22830. It has been proposed to short-circuit the exciter coil by connecting a voltage regulating semiconductor switch in parallel with the capacitor and making the voltage regulating semiconductor switch conductive when the charging voltage of the capacitor exceeds a set value.

FIG. 1 shows a circuit of a conventional ignition device of this type. In the figure, 1 is an ignition coil comprising a primary coil 1a and a secondary coil 1b;
The primary coil and one end of the secondary coil are grounded. Reference numeral 2 denotes a spark plug attached to a cylinder of an engine (not shown), and this spark plug is connected to a secondary coil of an ignition coil via a high voltage cord. 1
An ignition energy storage capacitor 3 is connected in series to the secondary coil 1a, and a discharge control thyristor 4 is connected in parallel to both ends of the series circuit between the capacitor 3 and the primary coil 1a, with its anode facing the ground side. ing. Reference numeral 5 denotes a signal coil that induces a signal of a predetermined level at the ignition timing of the engine. One end of this signal coil is grounded, and the other end is connected to the gate of the thyristor 4 through a diode 6. A signal supply circuit is constituted by the signal coil 5 and the diode 6, and when the signal coil 5 generates a signal of a predetermined level at the ignition timing of the engine, an ignition signal is supplied to the thyristor 4.

Reference numeral 7 denotes an exciter coil disposed in a magnet generator (not shown) driven by the engine, and this exciter coil induces an alternating current voltage in synchronization with the rotation of the engine. One end of the exciter coil 7 is grounded, and the other end is connected to a connection point between the capacitor 3 and the anode of the thyristor 4 via a rectifying diode 8. That is, the exciter coil 7 connects both ends of the series circuit of the capacitor 3 and the primary coil 1a to charge the capacitor 3 so that the terminal of the capacitor 3 connected to the anode of the discharge control thyristor becomes positive. rectifier diode 8
are connected in parallel via.

A damper diode 9 with its cathode facing the ground side is connected in parallel to both ends of the primary coil 1a, and the diode 9 diverts a portion of the charging current of the capacitor 3 from the primary coil.

A thyristor 10 as a voltage regulating semiconductor switch is connected in parallel to both ends of the exciter coil 7 with its cathode facing the ground side. Also, resistors 11 and 1 are connected to both ends of the exciter coil 7.
A resistive voltage divider circuit consisting of two series circuits is connected,
A voltage dividing point of the voltage dividing circuit is connected to the gate of the thyristor 10 via a Zener diode 13. Resistors 11, 12 and Zener diode 13
This constitutes a voltage detection circuit that supplies an ignition signal to the thyristor 10 when the output voltage of the exciter coil 7 exceeds a set value. In order to prevent the charging voltage from becoming excessive, a voltage adjustment circuit is configured to suppress the charging voltage of the capacitor 3 to below a certain value. A reverse output shorting diode 14 is also connected in parallel to both ends of the exciter coil 7 with its anode facing the ground side.

In the above ignition system, when the engine rotates,
An alternating current voltage is induced in the exciter coil 7, and current flows through the diode 8, capacitor 3, diode 9, and primary coil 1a at the voltage of one half cycle of the alternating current voltage, and the capacitor 3 is charged with the polarity shown. . In the above circuit, a damper diode 9 is connected to bypass the charging current of the capacitor 3 from the primary coil 1a, but all the charging current of the capacitor 3 is diverted from the primary coil through this damper diode 9. A part of the charging current flows through the primary coil 1a.
flows through. Signal coil 5 at engine ignition timing
When the thyristor 4 generates a signal, the thyristor 4 becomes conductive and the charge in the capacitor 3 is discharged through the thyristor 4 and the primary coil 1a of the ignition coil. This causes a large magnetic flux change in the iron core of the ignition coil,
A high voltage is induced in the secondary coil 1b. As a result, a spark is generated in the spark plug 2, and the engine is ignited.

When the engine speed increases and the instantaneous value of the half-cycle output voltage for charging the capacitor 3 of the exciter coil 7 exceeds the set value, the Zener diode 13 becomes conductive and the thyristor (semiconductor switch for voltage regulation) 10 is ignited. A signal is applied and the thyristor 10 becomes conductive. The output of the exciter coil 7 is therefore substantially short-circuited through the thyristor 10 and charging of the capacitor 3 is stopped. Therefore, the charging voltage of the capacitor 3 is suppressed to the set value, and the charging voltage of the capacitor 3 is prevented from becoming excessive.

As mentioned above, in a capacitor discharge type internal combustion engine ignition device equipped with a voltage adjustment circuit that suppresses the charging voltage of the capacitor 3 to a set value or less, when the semiconductor switch for voltage adjustment (the thyristor 10 in the above example) becomes conductive, Since the current that had been flowing through the primary coil 1a until then is cut off, a magnetic flux change occurs in the iron core of the ignition coil 1 during voltage adjustment, and a high voltage of about 1 kV is induced in the secondary coil 1b of the ignition coil. .
In this way, when the induced voltage in the secondary coil reaches about 1kV, sparks may occur in the ignition coil, which has the disadvantage that the engine is ignited at a time other than the ignition timing, which has an adverse effect on the engine.

Purpose of the invention The purpose of the present invention is to provide a capacitor discharge type internal combustion engine ignition device that prevents high voltage from being induced in the ignition coil when a voltage regulating semiconductor switch is turned on.

Structure of the invention The invention includes an ignition coil and one of the ignition coils.
An ignition energy storage capacitor connected in series to the secondary coil is connected in parallel to the series circuit of the primary coil and the capacitor, and when conductive, transfers the charge of the capacitor to the primary coil of the ignition coil. A discharge control thyristor that causes a coil to discharge, a signal supply circuit that supplies an ignition signal to the discharge control thyristor at the ignition timing of the internal combustion engine, and one end of the capacitor connected to the anode of the discharge control thyristor. An exciter coil is connected in parallel to both ends of the series circuit of the capacitor and the primary coil via a rectifying diode to charge the capacitor in one direction so as to make the charging current of the capacitor positive. a bypass diode connected in parallel to the primary coil to bypass the primary coil; a voltage regulating semiconductor switch connected in parallel to the exciter coil; and an output voltage of the exciter coil. An ignition device for an internal combustion engine, comprising a voltage detection circuit that detects a terminal voltage of the capacitor and supplies a trigger signal to a control terminal of the voltage regulating semiconductor switch when the detected voltage reaches a set value, This prevents high voltage from being induced in the ignition coil when the semiconductor switch for voltage adjustment is turned on. In the present invention, the charging current of the capacitor is prevented from flowing through the primary coil, and the discharging current of the capacitor is prevented from flowing through the primary coil. A blocking diode is inserted between the capacitor and the primary coil, oriented to permit flow through the primary coil.

In the above configuration, the signal supply circuit is not limited to that shown in FIG. 1, and may be any circuit that supplies an ignition signal to the discharge control thyristor at the ignition timing of the engine. For example, it is also possible to use a signal supply circuit that includes a circuit that shapes the output of the signal coil into a pulse shape.

The rectifying diode, the bypass diode, and the blocking diode are not limited to a single diode element, but may be a plurality of diode elements connected in series or parallel.

The voltage regulating semiconductor switch is not limited to a thyristor, but other controllable semiconductor switches such as transistors may also be used.

The voltage detection circuit is not limited to one that detects the voltage across the exciter coil, but may be a circuit that detects the voltage across the capacitor.

Effects of the Invention As described above, according to the present invention, a blocking diode is oriented to block the charging current of the capacitor from flowing through the primary coil of the ignition coil and to allow the discharging current of the capacitor to flow through the primary coil. Since it is inserted between the capacitor and the primary coil, it is possible to completely prevent the charging current of the capacitor from flowing to the primary coil of the ignition coil.
The primary current of the ignition coil is not cut off when the semiconductor switch for voltage regulation is turned on. Therefore, a high voltage is not induced in the secondary coil of the ignition coil when the voltage regulating thyristor is turned on, and it is possible to prevent ignition from occurring at a timing other than the ignition timing of the engine and adversely affecting the engine.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

FIG. 2 shows an embodiment of the present invention, in which the same parts as those in FIG. 1 are given the same reference numerals. In the embodiment of the present invention, the first
What is different from the device shown in the figure is that a diode 20 is installed between the capacitor 3 and the non-grounded terminal of the primary coil 1a of the ignition coil 1, with the anode facing the primary coil side.
This is the point where I inserted . Other points are similar to the apparatus shown in FIG.

In the above embodiment, the charging current of the capacitor 3 flows from the exciter coil 7 through the diode 8, the capacitor 3, and the diode 9, and no charging current flows through the primary coil 1a of the ignition coil. An ignition signal is applied to the thyristor 4 at the ignition timing of the engine, and when the thyristor becomes conductive, the capacitor 3 is discharged through the thyristor 4, the primary coil 1a, and the diode 20. As a result, a magnetic flux change occurs in the iron core of the ignition coil, and the secondary coil 1b
A high voltage is induced in the engine and the engine is ignited.

When the rotation of the engine increases and the instantaneous value of the output voltage of the exciter coil 7 exceeds the set value, an ignition signal is supplied to the thyristor 10, and the thyristor 10
conducts. Exciter coil 7 is therefore essentially short-circuited and charging of capacitor 3 is stopped.
Thereby, the charging voltage of the capacitor 3 is suppressed to the set value, and the charging voltage of the capacitor 3 is prevented from becoming a pedestal. At this time, the current in the primary coil 1a is not interrupted, so no high voltage is induced in the secondary coil 1b. Therefore, it is possible to prevent sparks from being generated in the spark plug at times other than the ignition timing of the engine.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a conventional device, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. 1...Ignition coil, 2...Spark plug, 3...
Ignition energy storage capacitor, 4... Thyristor for discharge control, 5... Signal coil, 6... Diode, 7... Exciter coil, 8... Diode, 9... Diode for bypass, 10... Thyristor (voltage adjustment) semiconductor switch), 11,
12...Resistor, 13...Zener diode.

Claims (1)

[Scope of utility model registration request] an ignition coil, an ignition energy storage capacitor connected in series to the primary coil of the ignition coil, and an ignition energy storage capacitor connected in parallel to the series circuit of the primary coil and the capacitor, and when the capacitor becomes conductive; a discharge control thyristor that discharges the charge to the primary coil of the ignition coil, a signal supply circuit that supplies an ignition signal to the discharge control thyristor at the ignition timing of the internal combustion engine, and an anode of the discharge control thyristor. an exciter coil connected in parallel to both ends of the series circuit of the capacitor and the primary coil via a rectifying diode to charge the capacitor in one direction so that one end of the capacitor on the coupled side has a positive polarity; a bypass diode connected in parallel to the primary coil to bypass the charging current of the capacitor from the primary coil; and a voltage regulating semiconductor switch connected in parallel to the exciter coil. and a voltage detection circuit that detects the output voltage of the exciter coil or the terminal voltage of the capacitor and supplies a trigger signal to the control terminal of the voltage regulating semiconductor switch when the detected voltage reaches a set value. In an ignition system for an internal combustion engine,
A blocking diode is inserted between the capacitor and the primary coil, oriented to block charging current of the capacitor from flowing through the primary coil and allowing discharge current of the capacitor to flow through the primary coil. An ignition device for an internal combustion engine characterized by: