JPH0988782A - Ignition control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to start up a boosting means by low voltage by providing a boosting means which has a semi-conductor switching means and which boosts the output voltage of an over-voltage protecting means to output it, and providing a parallel connecting means for connecting a power source input part to a driving means of the semi-conductor switching means of the boosting means. SOLUTION: A direct current-capacitor-discharge-ignitor 1A is provided with an over-voltage protecting circuit 10, a boosting means or a DC-DC converter 20A, a thyristor 40, a capacitor 30, etc. The DC voltage inputted to a terminal B is boosted to charge the capacitor 30. The thyristor 40 is ignited by a trigger signal applited to the thyristor 40 to feed discharge current to the primary winding 7a of an ignition coil 7. In this case, a parallel connection part 50 consisting of a diode 51 and a resistor 52 connected in series, is further provided. Thus, as a minimum supply voltage required at starting the ignitor 1A, low voltage of about 2.7V as compared to the conventional voltage of 4.2V is employed to start up the boosting means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine ignition control device suitable for use in a small two-wheeled vehicle or the like.

[0002]

2. Description of the Related Art Conventionally, an AC-CD has been used as an ignition control device for an internal combustion engine (hereinafter referred to as an engine) for a motorcycle.
I (AC-capacitor discharge igniter)
Has been widely used. The CDI instantly discharges the electric charge charged in the capacitor, and the discharge current is ignited.
It is applied to the primary winding of the coil and a high voltage is generated in the secondary winding to spark the spark plug.
AC-CDI derives the high voltage for charging the capacitor from the alternating voltage generated in the exciter coil provided in the alternator. This AC generator is connected to the crankshaft of the engine to rotate, and is provided to supply electric power to a battery and other electric loads.

On the other hand, due to recent advances in semiconductor technology, a DC-CDI (DC-capacitor discharge) that charges a capacitor by boosting a battery power supply, that is, a DC 12V power supply with a DC-DC converter, to generate a high voltage.
(Igniter) has been adopted in place of AC-CDI. When the DC-CDI is used, the exciter coil is not needed, and the configuration for extracting the output of the exciter coil can be omitted.
As compared with the case where I is used, the reliability and size of the system can be improved.

FIG. 4 is a circuit diagram showing the configuration of the current DC-CDI and its peripheral part applied to a small two-wheeled vehicle such as a motorbike. In FIG. 4, 1 is D
C-CDI, 2 are AC generators (ACG, only winding parts are shown) connected to an engine (not shown),
3 is a voltage regulator (REG-REC) that rectifies the output of the AC generator 2 and adjusts the voltage thereof, and 4 is a battery (BAT) to which the output of the voltage regulator 3 is connected. One of the terminals of the voltage regulator 3 is connected to the output terminal of the voltage regulator 3, a switch (SW) is turned on and off in conjunction with the operation of a brake lever or a brake pedal, and 6 is a stop lamp (S / L). . The output terminal of the voltage regulator 3, the positive terminal of the battery 4, and one terminal of the switch 5 are connected to the input terminal B of the DC-CDI 1.

Reference numeral 7 is an ignition coil, the primary winding 7a of which is connected to the output terminal I of the DC-CDI 1. The secondary winding 7b is connected to the spark plug 8. The other terminals of the AC generator 2, the battery 4, the stop lamp 6, the ignition coil 7, and the spark plug 8 are grounded.

The DC-CDI 1 includes an overvoltage protection circuit 10,
It is composed of a DC-DC converter 20, a thyristor 40 and a capacitor 30. Then, the DC voltage input from the input terminal B is boosted to charge the capacitor 30, and the thyristor 40 is ignited according to a trigger signal supplied to the gate terminal 40 _G from the outside (not shown) to output. It operates so that a discharge current flows through the primary winding 7a of the ignition coil 7 connected to the terminal I.

The overvoltage protection circuit 10 includes, for example, a thyristor 11 having an anode connected to a terminal B and a resistor 12 having one terminal connected to the terminal B as shown in FIG.
A Zener diode 13 whose cathode is connected to the other terminal of the resistor 12 and whose anode is grounded; a diode 14 whose anode is connected to the cathode of the Zener diode 13 and whose cathode is connected to the gate of the thyristor 11; A resistor 15 connected between the gate and cathode of 11 and an electrolytic capacitor 1 whose cathode is connected to the cathode of thyristor 11 and whose anode is grounded.
6 is comprised.

The overvoltage protection circuit 10 is provided with a circuit in the subsequent stage from an overvoltage of usually about 80 to 100 V due to a load dump surge or other spike voltage generated from the AC generator 2 when the positive terminal of the battery 4 is disconnected. For protection, the thyristor 11 is turned off when the terminal voltage of the electrolytic capacitor 16 becomes larger than the sum of the Zener voltage of the Zener diode 13, the forward voltage of the diode 14, and the forward voltage between the gate and cathode of the thyristor 11. Works like. Overvoltage protection circuit 10
Then, the constant of each element is set so that the thyristor 11 is turned off when a voltage exceeding about 20 V is input.

The DC-DC converter 20 includes a primary winding 2
A step-up transformer 21 composed of 1a and a secondary winding 21b,
FET (field effect transistor) 2 whose drain is connected to one terminal of the primary winding 21a and whose source is grounded 2
2, a gate drive circuit 23 for driving and controlling the gate of the FET 22 at high frequency, a terminal of the primary winding 21a on the side not connected to the FET 22, and a cathode of the thyristor 11 of the overvoltage protection circuit 10 and the gate of the FET 22. And a diode 25 having an anode connected to one terminal of the secondary winding 21b. The other terminal of the secondary winding 21b is grounded, and the cathode of the diode 25 is connected to the anode of the thyristor 40 and one terminal of the capacitor 30 described above.

Further, the gate drive circuit 23 includes an oscillator 231.
And a Zener diode 232 for overvoltage protection. The oscillator 231 generates a continuous pulse wave having a predetermined frequency and applies this between the gate and the source of the FET 22 to control the FET 22 on / off. In this case, the gate of the FET 22 is always pulled up by the DC voltage output from the overvoltage protection circuit 10 via the resistor 24, so that the FET 22 operates when the output stage of the oscillator 231 is in a high impedance (off) state, for example. It turns on, and conversely turns off when the output stage of the oscillator 231 enters a low impedance (on) state.

The oscillator 231 may be configured as a self-excited circuit that uses multiple windings of the step-up transformer 21, which is not shown, or may be configured as a separately excited circuit that uses an independent CR oscillator or the like. Further, the commutation failure can be prevented by suspending the oscillator 231 during the period during which the thyristor 40 is ignited and during the period until the thyristor 40 is completely turned off (commutation turn-off time).

In the DC-DC converter 20 having the above-described structure, the FET 22 is switching-driven to cause a pulse train-like current to flow in the primary winding 21a of the step-up transformer 21 to boost the voltage between the terminals of the secondary winding 21b. AC voltage is generated. The output of the secondary winding 21b is half-wave rectified by the diode 25, and the half-wave rectified current charges the capacitor 30.

The DC-CDI 1 shown in FIG. 4 described above is here.
The minimum operating voltage, that is, the minimum input voltage required to spark the spark plug will be described. In addition,
In FIG. 4, the following description will be made assuming that the anode terminal of the thyristor 11 is the terminal T ₁ and the cathode terminal is the terminal T ₂ .
The minimum voltage required for the operation of the DC-DC converter 20 is determined depending on the ON voltage between the gate and the source of the FET 22, and when a general-purpose circuit element is used, the resistance 2
The voltage between the terminal T ₂ including 4 and the ground is about 1.5V.

On the other hand, the minimum voltage required for the operation of the overvoltage protection circuit 10 depends on the forward voltage of the diode 14, the gate voltage of the thyristor 11, and the resistance values of the resistors 12 and 15 at the time of start-up when the thyristor 11 is turned on. The voltage between the terminals T _{1 and} T ₂ is determined to be about 2.
It becomes 7V. However, once the thyristor 11 is activated, the voltage between the terminals T _{1 and} T ₂ becomes equal to the ON voltage of the thyristor 11 and becomes about 0.8V. Therefore, at start-up, a voltage of about 4.2V (1.5V + 2.7V) between the terminal T ₁ and the ground, that is, the terminal voltage of the input terminal B is DC−.
This is the minimum operating voltage of CDI1.

[0015]

By the way, a small two-wheeled vehicle is usually provided with a kick pedal together with a self-motor as a device for starting an engine.
For example, in the circuit shown in FIG. 4, when the battery 4 is over-discharged, the battery 4 is deteriorated, or the terminals of the battery 4 are disconnected, the starter motor cannot be driven. The pedal will be used to start the engine. At that time, DC-CD
The output of the alternator 2 that rotates with the depression of the kick pedal is supplied to I1 directly as an input power source, not from the battery 4.

On the other hand, when the engine is started by the kick pedal, in many cases, the driver depresses the pedal with the brake pedal held (the switch 5 is on). Therefore, when the alternator 2 is driven by the operation of the kick pedal and power generation is started, the stop lamp 6 is connected to the output of the alternator 2 as an electric load. In such a case, the output of the AC generator 2 does not rise sufficiently, the input voltage of the DC-CDI 1 does not reach the above-mentioned minimum operating voltage, and the engine cannot be started.

The table below shows an example of the measured values of the relationship between the input voltage of the DC-CDI 1, the operating strength of the kick pedal, and the capacity of the stop lamp 6. The measured values in the table below are measured with the battery 4 removed. Regarding the strength of depression of the kick pedal, an average value by a woman is represented by a medium kick, and an average value by a man is represented by a strong kick.

[0018]

[Table 1]

As described above, in the above-mentioned conventional DC-CDI, the input voltage becomes insufficient when the kick pedal is depressed, and D
There is a problem in that the internal circuits of the C-CDI cannot be activated, and therefore the spark plug cannot generate sparks, and the engine cannot be started in some cases.

The present invention has been made under such a background, and an object thereof is to provide an internal combustion engine ignition control device which can be started with a low input voltage which could not be started by a conventional device. To do.

[0021]

In order to solve the above-mentioned problems, the invention according to claim 1 has a first semiconductor switching means and is connected to a power supply input section from the outside to input an overvoltage. An overvoltage protection means for preventing an overvoltage from passing by sometimes shutting off the first semiconductor switching means, a second semiconductor switching means, and a driving means for the second semiconductor switching means are provided. Boosting means connected in series with the boosting means for boosting and outputting the output voltage of the overvoltage protection means, and a driving means for the second semiconductor switching means of the power source input section and the boosting means, which is configured without the semiconductor switching means. Is connected without passing through the first switching means, charging means charged by the output of the boosting means, and the electric charge charged in the charging means from the outside. It is characterized by comprising a discharge means for discharging in accordance with the command.

According to a second aspect of the present invention, the overvoltage protection means further includes a resistance element whose one end is connected to the power supply input portion and an overvoltage absorption element connected to the other end of the resistance element.
It is characterized in that the parallel connecting means connects the power supply input section and the driving means of the second semiconductor switching means of the boosting means via the resistance element without passing through the first switching means.

According to a third aspect of the present invention, there is provided a first thyristor, which is connected to an external power source input section, and when the overvoltage is input, the first thyristor is cut off to prevent the overvoltage from being applied. An overvoltage protection circuit that protects the circuit in the latter stage,
A DC-DC converter that has a step-up transformer and an FET connected in series to the output terminal of the overvoltage protection circuit, and a gate drive circuit of the FET, and boosts the DC voltage output from the overvoltage protection circuit to output the DC voltage. A parallel connection part configured without a semiconductor switching element, connecting the power supply input part and the gate drive circuit without passing through the first thyristor, and a capacitor charged by the output of the DC-DC converter, And a second thyristor that fires in response to a control signal from the outside and discharges the electric charge of the capacitor.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a circuit diagram showing a configuration of a DC-CDI (internal combustion engine ignition control device) according to an embodiment of the present invention. In this figure, parts corresponding to respective parts in FIG. Is omitted. 1A is DC-CDI, 20A is DC-D.
The C converter and 23A are gate drive circuits, respectively, and are DC-CDI1 and DC-DC converter 2 shown in FIG.
0, which has the same function as the gate drive circuit 23.

Reference numeral 50 denotes a parallel connection portion, which is newly provided in the DC-CDI 1A in place of the resistor 24 shown in FIG. 4 according to the present invention. The parallel connection section 50 includes a diode 51 and a resistor 52 that are connected in series, and directly connects the input terminal B to the gate of the FET 22 and the gate drive circuit 23A without the overvoltage protection circuit 10. As described above, in the present embodiment, by providing the parallel connection portion 50 in parallel with the overvoltage protection circuit 10, the power supply voltage is directly supplied from the input terminal B to the gate drive circuit 23A without passing through the thyristor 11.

Therefore, according to the present embodiment, the voltage of the input terminal B is the forward voltage of the diode 51 (terminal T ₁
-T voltage between ₃₎ about 0.65V and the terminal T ₃ - about the voltage between ground 1.5V (terminal of FIG. 4 T ₂ - between ground ones voltage similar to the) and approximately 2.15V of plus When the voltage is equal to or higher than the voltage, the DC-DC converter 20A is ready for operation, that is, the FET 22 is in a conductive state.
The minimum power supply voltage at the input terminal B required for starting the I1A is determined by the voltage required for starting the overvoltage protection circuit 10. That is, the minimum power supply voltage required at the input terminal B at the time of startup is 2.7V. Note that these voltage values are examples of typical values at room temperature.

In this case, in the parallel connection section 50, the diode 51 causes the gate drive circuit 23 to operate from the external surge of negative polarity.
The resistor 52 is provided to protect the gates of the FET 22 and the A, and the resistor 52 is provided to protect the gates of the oscillator 231 and the FET 22 from a positive overvoltage by working together with the Zener diode 232 in the gate drive circuit 23A. It has been done. This resistor 52 corresponds to the above-mentioned 1
Since it becomes a resistance when the overvoltage of about 00V is absorbed by the Zener diode 232, it is desirable to set it to a relatively large value in order to suppress the surge allowable rating of the Zener diode 232. On the other hand, the power supply for driving the gate of the FET 22 is supplied through the resistor 52, so if the resistance value is increased, the FET 22
There is a problem that the switching speed of is slow.
However, since the FET 22 is a voltage-driven switching element, there is no problem in the on / off operation itself even if the resistance value is large to some extent.

The forward characteristic of the Zener diode 232 can be used for absorbing the negative surge. Further, since the overvoltage protection circuit 11 protects the overvoltage applied between the drain and the source of the FET 22 as in the conventional case, the FET 22 can be an element of the same standard as the conventional case.

As described above, according to the present embodiment, since the parallel connection portion 50 is provided in parallel with the overvoltage protection circuit 10, the minimum power supply voltage required when the DC-CDI 1A is started up is about 2.7V. Therefore, it can be made lower than 4.2V of the conventional example described with reference to FIG. Therefore, even when the alternating current generator 2 is under an electric load and the kick pedal is depressed with a medium strength under the conditions as summarized in the above table, the DC-
The CDI 1A can be activated and a discharge current can be output from the output terminal I. Therefore, even in such a case, a spark can be generated by the spark plug 8 and the engine can be started.

Next, referring to FIG. 2, the second embodiment of the present invention will be described.
The embodiment will be described. In FIG. 2, 20
B, 23B, and 50B are DC-D shown in FIG. 1, respectively.
This is a configuration corresponding to the C converter 20A, the gate drive circuit 23A, and the parallel connection section 50, and is a feature of the present embodiment. The other parts are configured in the same manner as the parts denoted by the same reference numerals in FIG. In the second embodiment, unlike the first embodiment, the connection point on the input side of the parallel connection section 50B is the connection point between the resistor 12 and the Zener diode 13 in the overvoltage protection circuit 10, and the parallel connection section 50B Is composed of only the resistor 52B, and the DC-DC converter 20B is connected to the gate drive circuit 23.
It consists of only one. That is, as compared with the first embodiment, the Zener diode for surge absorption is omitted in the DC-DC converter 20B, and the diode for surge absorption is omitted in the parallel connection portion 50B. Resistance 5
The resistance value of 2B may be the same as that of the resistor 52 of the first embodiment.

Since the Zener diode 13 normally has a sufficient surge allowable rating in view of the operational requirements of the overvoltage protection circuit 10, the Zener diode 13 absorbs surges of both positive and negative polarities by the above configuration. Thus, each surge absorbing element provided in the first embodiment can be omitted. On the other hand, in the present embodiment, as compared with the first embodiment, since power is supplied to the gate drive circuit 23A via the resistor 12, the voltage drop caused by the resistor 12 causes the minimum amount at the time of starting the gate drive circuit 23A. On the other hand, the operating voltage becomes high, but on the other hand, since the diode is omitted from the parallel connection section 50B, the gate drive circuit 2 is accordingly reduced.
The minimum operating voltage at the time of starting 3A becomes low. as a result,
The minimum voltage required for starting the DC-CDI 1B as a whole is about 2.7V at the input terminal B.

Next, referring to FIG. 3, the third embodiment of the present invention will be described.
The embodiment will be described. DC-C shown in this figure
DI1C differs from DC-CDI1B shown in FIG. 2 in that
The input side of the parallel connection part 50B is connected to the cathode side of the diode 14 in the overvoltage protection circuit 10.
According to the present embodiment, the voltage drop from the input terminal B to the gate drive circuit 23B is increased by the amount of the voltage drop due to the diode 14 as compared with the second embodiment.
The voltage required for starting the DC-CDI 1C as a whole is higher than that in the first and second embodiments, and is about 3.5V. However, even in this case, the operation can be started at a voltage lower than 4.2V which is required in the conventional device described with reference to FIG.

The first embodiment described with reference to FIGS.
The arrangement of each surge absorbing element in the third embodiment is not limited to the above, and for example, the diode 51 in FIG. 1 may be omitted, and the circuit examples in FIGS. 2 and 3 may be the same as in FIG. It is possible to add a Zener diode 231 and make changes such as adding elements such as capacitors to each part.

[0034]

According to the first aspect of the invention, the parallel connecting means, which is configured without the semiconductor switching means, includes the power supply input section and the driving means of the second semiconductor switching means of the boosting means as the first means. Since the connection is made without passing through the semiconductor switching means, it is possible to start the boosting means at a lower voltage than the conventional one.

According to the second aspect of the present invention, the overvoltage protection means includes the resistance element and the overvoltage absorption element, and the parallel connection means of the second semiconductor switching means of the power supply input section and the boosting means via the resistance element. Since the driving means is connected without passing through the first switching means, it is possible to prevent the overvoltage from being applied to the driving means of the second semiconductor switching means by using the overvoltage absorbing element of the overvoltage protection means.

According to the third aspect of the present invention, the parallel connection section configured without the semiconductor switching element connects the power supply input section and the gate drive circuit without passing through the first thyristor, and also the FET. Since the DC-DC converter is configured by using, the value of the current required for the gate drive circuit to drive the gate can be reduced, and therefore the DC-DC converter can be started at a lower voltage than the conventional one. In addition, it is possible to easily downsize the configuration of the parallel connection portion.

[Brief description of drawings]

FIG. 1 is a DC-CD according to a first embodiment of the present invention.
It is a circuit diagram which shows the circuit structure of I and its peripheral part.

FIG. 2 is a DC-CD according to a second embodiment of the present invention.
It is a circuit diagram which shows the circuit structure of I and its peripheral part.

FIG. 3 is a DC-CD according to a third embodiment of the present invention.
It is a circuit diagram which shows the circuit structure of I and its peripheral part.

FIG. 4 is a circuit diagram showing a circuit configuration of a conventional DC-CDI and its peripheral portion.

[Explanation of symbols]

 1A, 1B, 1C DC-CDI 10 Overvoltage protection circuit 20A, 20B DC-DC converter 23A, 23B Gate drive circuit 30 Capacitor 40 Thyristor 50, 50B Parallel connection part 51 Diode 52 Resistance

Claims (3)

[Claims] 1. A first semiconductor switching means is provided,
An overvoltage protection unit connected to an external power supply input unit to prevent an overvoltage from passing by shutting off the first semiconductor switching unit when an overvoltage is input; a second semiconductor switching unit; A second semiconductor switching means driving means, which is connected to the overvoltage protection means in series and boosts and outputs the output voltage of the overvoltage protection means; and a semiconductor switching means is not provided. Parallel connection means for connecting the power supply input section and drive means for the second semiconductor switching means of the boosting means without passing through the first switching means; charging means for charging by the output of the boosting means; An internal combustion engine ignition control device, comprising: a discharging unit that discharges the electric charge charged in the charging unit according to an external command. 2. The overvoltage protection means further includes a resistance element whose one end is connected to the power supply input section and an overvoltage absorption element connected to the other end of the resistance element, and the parallel connection means is the resistance element. 2. The ignition control device for an internal combustion engine according to claim 1, wherein the power source input section and the driving means of the second semiconductor switching means of the boosting means are connected via the first bypass means without passing through the first switching means. . 3. A first thyristor is provided, which is connected to a power supply input section from the outside and shuts off the first thyristor when an overvoltage is input, thereby protecting a circuit in the subsequent stage from the overvoltage. An overvoltage protection circuit, a step-up transformer and an FET connected in series to the output terminal of the overvoltage protection circuit, and a gate drive circuit for the FET are provided, and a DC voltage output from the overvoltage protection circuit is boosted to generate a DC voltage. A DC-DC converter for outputting, a parallel connection section configured without a semiconductor switching element, for connecting the power supply input section and the gate drive circuit without passing through the first thyristor, and the DC-DC A converter is provided with a capacitor charged by the output of the converter, and a second thyristor that fires in response to a control signal from the outside and discharges the electric charge of the capacitor. An internal combustion engine ignition control apparatus according to claim and.