JPH01211664A - Capacitor electric-discharging type ignition device - Google Patents

Abstract

PURPOSE:To prevent reduction in duration time of sparking by connecting a diode to a short-circuit line which short-circuits a series circuit consisting of an ignition capacitor and the primary coil of an ignition coil. CONSTITUTION:A parallel circuit consisting of an advancing capacitor 31 and a resister 32 between the gate and the cathode of a thyristor 28 as a semi- conductive switching element. A short-circuit line 34 which short-circuits a series circuit consisting of an ignition capacitor and the primary coil of an ignition coil is configurated and a diode 37 which allows the discharge of reverse-polarity electric charge only of the ignition capacitor 22 is connected to the short-circuit line 34. The electric charge of the reverse polarity charged after the electric charge of the ignition capacitor 22 discharged via the thyristor 28 is discharged via the short-circuit line 34. As a result, the electric charge is consumed effectively at the ignition coil 23 so that the duration time of the sparking may be prevented from reducing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application) The present invention relates to a capacitor discharge type ignition device used in a spark-ignition internal combustion engine, and in particular, the present invention relates to a capacitor discharge type ignition device used in a spark ignition type internal combustion engine. The present invention relates to an ignition device in which a semiconductor switching element is made conductive by a negative output that is subsequently generated, and the charge of a capacitor is rapidly supplied to an ignition coil.

KSummary of the Invention The present invention provides a short-circuit path that short-circuits a series circuit between an ignition capacitor and a primary coil of an ignition coil, and connects a diode that only allows discharge of opposite polarity charges of the ignition capacitor to this short-circuit. By connecting the ignition capacitor to the ignition capacitor, the reverse polarity charge is not consumed in the parallel circuit of the advance capacitor and the resistor. The middle tap of the generating coil and the primary coil of the ignition coil are connected through the middle tap of the generating coil, and when the engine speed increases and the inductance of the generating coil becomes high, the generated output is taken out through the middle tap of the generating coil. This prevents the output of the generator coil from decreasing when the engine speed increases.

K. Prior Art) 1 A conventional =1 denser discharge type ignition device used in a spark ignition type internal combustion engine is known, for example, from Japanese Patent Application Laid-open No. 189363/1983. This ignition system is designed as shown in FIG. 4, and charges the positive direction output generated by the generating coil 1 to a capacitor 3 through a diode 2, and charges the negative direction output generated by the generating coil 1 to a resistor 4. 17'' to the gate of the thyristor 5. This makes the thyristor 5 conductive, and the charge stored in the capacitor 3 is transferred to the anode of the thyristor 5, the cathode, the diode 6, and the primary coil of the ignition coil 7. 8, flows in the order of capacitor 3, 1 of ignition coil 7
A current suddenly flows through the next coil 8. This induces a high voltage in the secondary coil 9 of the ignition coil 7,
A spark is generated at the spark plug 10.

In such an ignition device, the gate of the thyristor 5
A parallel circuit of a capacitor 11 and a resistor 12 is connected between the cathodes, and a diode 13 is connected directly 511 to this parallel circuit. Therefore, a part of the output of the generator coil 1 in the negative direction flows into the capacitor 11 through the diode 13, and the capacitor 11 is charged. This means that by providing the capacitor 11, the gate current of the thyristor 5 is reduced and a retarded operation is performed. Then, when the engine speed increases, the next charge is performed before the discharge of the capacitor 11 is completed, so that the capacitor 1
The voltage across capacitor 1 gradually increases, and the current flowing into capacitor 11 decreases. Therefore, as the rotational speed of the engine increases, the gate current of the thyristor 5 increases 710-, and an advance operation is performed, making it possible to obtain an ignition device having the characteristics shown by the dotted line in FIG.

Problems to be Solved by the Invention A drawback of such conventional ignition devices is the short duration of the spark. That is, the voltage of the capacitor 3 becomes as shown in FIG. 5, and after the charges in the positive direction are discharged, the charges that have passed through the ignition coil 70 and the primary coil 8 are charged in the reverse direction. The ignition energy is represented by the sum of the positive direction voltage area S and the negative direction voltage S2 in FIG.

However, the charge S2 in the negative direction is caused by the capacitor 3, the ignition coil 70, the primary coil 8, the diode coil 3, the parallel circuit of the capacitor 11 and the resistor 12, the diode 14, the diode 2,
It flows in the order of capacitor 3 and is consumed by capacitor 11 and resistor 12 at this time. i.e. capacitor 1
Since energy is absorbed by the parallel circuit of 1 and resistor 12, the negative charge of capacitor 3 does not contribute effectively to ignition, and the duration of the spark is shortened.

The present invention has been made in view of these problems, and it is an object of the present invention to provide a capacitor discharge type ignition device with a long spark duration.

[Means for Solving the Problems] The first invention of the present application charges an ignition capacitor by the positive output of the power generation coil, and charges a semiconductor switching element by the negative output generated by the power generation coil. In the ignition device, the ignition capacitor is electrically conductive and the electric charge of the ignition capacitor is suddenly supplied to the ignition coil. A short-circuit path is provided to short-circuit the series circuit between the ignition capacitor and the primary coil of the ignition coil, and a diode that only allows discharge of charges of opposite polarity of the ignition capacitor is connected to the short-circuit path.
This is the one that was designed to connect.

Further, in the second invention of the present application, a parallel circuit of an advance angle capacitor and a resistor is connected between the gate and cathode of the semiconductor switching element, and an intermediate tap is provided in the generating coil, so that only the positive direction output of the generating coil is provided. The intermediate tap of the generating coil and the primary coil of the ignition coil are connected via a diode that allows the ignition coil to pass through.

K effect] According to the first invention, the charge of opposite polarity that is charged after the charge of the ignition capacitor is discharged through the semiconductor switching element shorts the series circuit between the ignition capacitor and the primary coil of the ignition coil. will be discharged through a short circuit.

Further, according to the second invention ζ, when the engine speed increases, the power generation output is taken out through the intermediate tap of the generator coil, and the inductance of the generator coil increases as the engine speed increases. This makes it possible to compensate for the decrease in power generation output due to the increase in .

K Embodiment] FIG. 1 shows a capacitor discharge type ignition device according to an embodiment of the present invention.
Q, and the capacitor 2 is connected via the diode 21.
It is designed to be connected to 2. and capacitor 2
2 is further connected to a primary coil 24 of an ignition coil 23. Secondary coil 25 of ignition coil 23
is connected to the spark plug 26. Further, the primary coil 24 of the ignition coil 23 is connected to the negative terminal of the generator coil 20 via a diode 27.

The anode of a thyristor 28 is connected to the connection point between the diode 21 and the capacitor 22. The gate of this thyristor 28 is connected to the negative terminal of the power generating coil 20 via a resistor 29. Further, a resistor 30 is connected between the gate and cathode of this thyristor 28. Furthermore, this ignition device includes a capacitor 31 and a resistor 32.
This parallel circuit is connected to diode 3.
3 and in parallel to the series circuit of resistors 29 and 30.

Further, a short circuit 34 is connected between the cathode of the thyristor 28 and the negative terminal of the primary coil 24 of the ignition coil 23. Further, a diode 35 is connected between the cathode and anode of the thyristor 28. In addition, the generating coil 20 has an intermediate tap 36
The intermediate tap 36 and the cathode of the thyristor 28 are connected via a diode 37.

In the above configuration, the generator coil 20 (L) is designed to generate an output waveform as shown in FIG. 2, first producing an output in the positive direction, and then producing an output in the negative direction. There is.

The positive output of the generator coil 20 is transmitted from its positive terminal to the diode 21, capacitor 22, and ignition coil 23.
The current flows through the primary coil 24, the diode 27, and the negative terminal of the generator coil 20 in this order, and at this time, the capacitor 2
2 to the polarity shown. Therefore, energy for ignition is stored in the capacitor 22.

Next, when the generator coil 20 generates an output in the negative direction, the output is supplied from the negative terminal of the coil 20 through the diode 33 to the parallel circuit of the capacitor 31 and the resistor 32.

Then, a current flows from this parallel circuit through the diode 137 and back to the center tap 36 of the generator coil 20. Furthermore, a part of the output on the negative side of the generator coil 20 is
As well as flowing from the resistor 29 to the resistor 30, a portion of the current flows in %? A is applied from resistor 29 to the gate of thyristor 28, making thyristor 28 conductive.

When the thyristor 28 is turned on, the charge stored in the capacitor 22 is transferred from the capacitor 22 to the thyristor 28.
A current flows through the anode, the cathode, the short-circuit path 34, the ignition coil 230, the primary coil 24, and the negative terminal of the capacitor 22 in order to cause discharge. At this time, a high voltage is induced in the ignition coil 230 and the secondary coil 25.

This high voltage causes the plug 26 of the ignition coil 23 to generate a spark, igniting the engine.

In such an ignition device, the timing of ignition is determined by the timing at which the thyristor 28 becomes conductive. The timing at which the thyristor 28 becomes conductive is determined by the ratio of the current flowing from the diode 33 to the capacitor 31 and the resistor 32 to the current flowing to the resistor 29.30. The timing (J, J,
There will be a delay compared to the case without the three capacitors.

While the time constant of the circuit consisting of the capacitor 31 and the resistor 32 is constant, the period of one revolution of the engine becomes shorter as the number of revolutions increases.

Therefore, it is possible to set the parallel circuit of the capacitor 31 and the resistor 32 so that the voltage of the capacitor 31 changes from the 1 state shown by the solid line to the state shown by the dotted line and roughly to the state shown by the chain line in FIG. Become. That is, by setting the voltage of the capacitor 31 to rise as the engine speed increases, the charging current to the capacitor 31 is reduced as the engine speed increases, and the thyristor 28 The timing of conduction can be made earlier as the engine speed increases. This means that as the engine speed increases, the ignition timing advances. This advance angle characteristic depends on the negative output waveform generated by the generator coil 20 and the time constant of charging and discharging by the capacitor 31 and resistor 32, and for example, the characteristics shown in FIG. 3 can be obtained. Become.

As the engine speed increases, the generator coil 20
The inductance of increases gradually. Therefore, departure? The amount of current passing through the coil 20 decreases, the rate of increase in the output of the generator coil 20 decreases, and the rate of increase in the voltage of the capacitor 31 also decreases, and the advance angle eventually stops.

As the engine speed increases and enters the high speed range,
The inductance of the generator coil 20 further increases. Therefore, the output of the generator coil 20 is significantly reduced and the engine is retarded, making it impossible for the engine speed to increase. Such characteristics are shown by dotted lines in FIG. In order to prevent angle lag in such a high speed rotation range, an intermediate tap 36 is provided in the generating coil 20.
This is to prevent the output from decreasing due to the inductance of the generator coil 20.

This operation is performed as follows. Generator coil 2
When the inductance at 0 becomes high and it becomes difficult for current to flow across it, the positive output of the generator coil 20 causes
Current flows through the diode 21, the capacitor 22, the primary coil 24, the short circuit 34, the diode 37, and the intermediate tap 36 in this order. The proportion of this current gradually increases compared to the proportion of current flowing through the entire generating coil 20. Moreover, since the intermediate tap 36 prevents the current from decreasing due to an increase in the inductance of the generating coil 20, it is possible to prevent the output of the generating coil 20 from decreasing in the high speed range. This makes it possible to change the characteristic shown by the dotted line in FIG. 3 to the characteristic shown by the solid line.

Furthermore, this ignition device is equipped with a diode 35,
This diode 35 prevents the duration of the spark from decreasing. After the thyristor 28 is turned on and the positive charge of the capacitor 22 is discharged, the capacitor 22 is charged with a charge of the opposite polarity (see Fig. 5).
. And if there is no diode 35, capacitor 2
The charge of opposite polarity of 2 is transferred from the capacitor 22 to the primary coil 24.
, the short circuit 34, the diode 37, the intermediate tap 36, the positive terminal of the generator coil 20, the diode 21, and the loop of the capacitor 22.

Therefore, the opposite polarity charge of the capacitor 22 is consumed between the intermediate tap 36 of the generating coil 20 and the positive terminal.

However, if the diode 35 is connected as shown in FIG.
．． The energy is discharged in the loop of the primary coil 24, the short circuit 34, the diode 35, and the capacitor 22, and is no longer consumed in the generating coil 20, but the energy is effectively consumed by the primary coil 24. Therefore, from this, the charge of the opposite polarity of the capacitor 22 is not wasted and is effectively used by the ignition coil 23, thereby preventing a decrease in the duration of the spark generated by the spark plug 26. becomes possible.

Effects of the invention] The first invention of the present application connects a parallel circuit of an advance angle capacitor and a resistor between the gate and cathode of a semiconductor switching element, and connects a series circuit of an ignition capacitor and a primary coil of an ignition coil. A short-circuit path is provided to short-circuit the ignition capacitor, and a diode is connected to the short-circuit path to allow only the discharge of the charge of the opposite polarity of the ignition capacitor. Therefore, according to such a configuration, the charge of the opposite polarity of the ignition capacitor is discharged through the short circuit having the diode, and is effectively consumed in the ignition coil, thereby reducing the duration of the spark. It becomes possible to prevent this.

In addition, the second invention of the present application connects a parallel circuit of an advance angle capacitor and a resistor between the gate and cathode of the semiconductor switching element, and also provides an intermediate tap in the generating coil to pass only the positive output of the generating coil. The intermediate tab of the power generation coil and the primary coil of the ignition coil are connected through a diode. Therefore, when the engine speed increases and the inductance of the generator coil increases, the current flowing through the intermediate tap increases, thereby making it possible to compensate for the decrease in the output of the generator coil in the high speed range.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an ignition device according to an embodiment of the present invention, Fig. 2 is a waveform diagram showing the operation of this ignition device, Fig. 3 is a graph showing characteristics of the ignition angle, and Fig. 4 is a conventional FIG. 5 is a graph showing the operation of the ignition system. In addition, in the symbols used in the drawings, 20... Generator coil 21... Diode 22... Ignition capacitor 23... Ignition coil 24... Primary coil 25... Secondary coil 26... Spark plug 28...Thyristor 29...Resistor 31...Advance capacitor 32...Resistor 34...Short circuit 35...Diode 36...Intermediate tap 37...Diode τ'' exists .

Claims (1)

[Claims] 1. The ignition capacitor is charged by the positive output of the generating coil, and the semiconductor switching element is made conductive by the negative output generated by the generating coil, and the ignition capacitor is In an ignition device that rapidly supplies the charge of a capacitor to an ignition coil, a parallel circuit of an advance capacitor and a resistor is connected between the gate and cathode of the semiconductor switching element, and a parallel circuit of an advance capacitor and a resistor is connected between the ignition capacitor and the ignition coil. A capacitor discharging type, characterized in that a short-circuit path is provided to short-circuit a series circuit with the primary coil of the ignition capacitor, and a diode that only allows discharge of charges of opposite polarity of the ignition capacitor is connected to the short-circuit path. Ignition device. 2. The ignition capacitor is charged by the positive output of the generator coil, and the semiconductor switching element is made conductive by the negative output generated by the generator coil, and the charge of the ignition capacitor is rapidly supplied to the ignition coil. In the ignition device, a parallel circuit of an advance angle capacitor and a resistor is connected between the gate and cathode of the semiconductor switching element, and an intermediate tap is provided in the generator coil, so that only the positive direction output of the generator coil is provided. A capacitor discharge type ignition device, characterized in that the intermediate tap of the generating coil and the primary coil of the ignition coil are connected via a diode that allows the passage of the ignition coil.