JP2002070705A - Capacity discharge type ignition system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacity discharge type ignition system for a motorcycle which can correctly detect the charging voltage of a condenser 4 even when an ignition coil 2 is detached. SOLUTION: In the condenser discharging circuit 7 through a condenser 4, thyristor 5, GND 40, the primary coil 11 of an ignition coil 2 to a condenser 4, a fixed resistor 30 having an electric resistance which enables the electric current between and anode and a cathode of the thyristor an off condition is connected in parallel to the primary coil 11 of the ignition coil 2. Thereby, the charged voltage of condenser 4 can be detected by a Zener diode 31 based on GND 40 which is connected through the fixed resistor 30 even when the ignition coil 2 is detached. Accordingly, the operation of DC-DC converter can be completely stopped when the charged voltage of the condenser 4 is increased to the specified value or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor charging circuit in which a capacitor is charged once, and a thyristor is turned on in synchronization with an ignition timing to discharge the charged capacitor to a primary winding of an ignition coil at once. The present invention relates to a capacitive discharge ignition device to be operated.

[0002]

2. Description of the Related Art Conventionally, as a capacitor charging circuit for charging a capacitor 101, as shown in FIG. 6, a 12V DC is converted into an AC by a power transistor 114, which is boosted by a transformer 102 to about 15
0 to 250 V AC, and this AC is
The DC-DC converter 110 which rectifies the DC-DC power of the DC-DC converter 5 to obtain a direct current of about 150 to 250 V is employed. Then, the DC of about 150 to 250 V is stored in the capacitor 101 (charging), a signal is sent to the gate of the thyristor 103 by a signal generator at the time of ignition, the thyristor 103 is turned on, and the charge of the charged capacitor 101 is ignited at once. Coil 10
There is known a capacity discharge type ignition device in which a primary winding 141 is discharged.

[0003] Such a capacitive discharge type ignition device employs an AC arc system which can lengthen the discharge time of the capacitor 101. And the ignition coil 1
04 is normally connected, the GND connected via the primary winding 141 of the ignition coil 104
(Ground), a capacitor charge voltage detection path A (GND) for detecting the charge voltage of the capacitor 101
→ the primary winding 141 of the ignition coil 104 → the capacitor 101 → the Zener diode 107 → the transistor 108). Therefore, when the charging voltage becomes equal to or higher than the predetermined value, the base current of the power transistor 116 is turned off, and the current of the primary coil 121 of the transformer 102 is cut off, so that the charging of the capacitor 101 can be stopped.

[0004]

However, in the conventional capacitive discharge ignition device, if the ignition coil 104 comes off, for example, an abnormality in the wire harness, disconnection of the primary winding 141 of the ignition coil 104, or ignition coil In the case of the product GND of 104, etc., the capacitor charging voltage detection path A for detecting the charging voltage of the capacitor 101 is eliminated. As a result, the charging voltage of the capacitor 101 cannot be detected, and the charging of the capacitor 101 cannot be stopped even if the charging voltage of the capacitor 101 exceeds a predetermined value.
C-DC converter 110 continues to operate, and in the worst case, DC-
There is a problem that a problem such as heat generation of the DC converter 110 occurs.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to ensure that the charging voltage of a capacitor can be detected even if an ignition coil comes off by inserting an electric resistance means in a product. Another object of the present invention is to stop the operation of a capacitor charging circuit such as a DC-DC converter when the charging voltage of the capacitor becomes a predetermined value or more even when the ignition coil comes off.

[0006]

According to the first aspect of the present invention, after the capacitor charging circuit is operated to store electric charge in the capacitor, the thyristor is operated at a predetermined ignition timing to store the electric charge in the capacitor. In a capacitive discharge igniter in which the electric charge is discharged to the primary winding of the ignition coil at a stretch, an electric resistance means having a predetermined electric resistance value is connected in parallel to the primary winding of the ignition coil.

With this arrangement, not only a normal capacitor charge voltage detection path for detecting the charge voltage of the capacitor with reference to the ground connected through the primary winding of the ignition coil but also the electric resistance means is provided. An emergency capacitor charging voltage detection path for detecting the charging voltage of the capacitor is formed with reference to the connected ground. Therefore, even when the ignition coil comes off, the charged voltage of the capacitor can be reliably detected.

According to the second aspect of the present invention, when the charging voltage of the capacitor detected by the charging voltage detecting means is equal to or higher than a predetermined value, the charging operation stopping means for stopping the operation of the capacitor charging circuit is provided. Even when the ignition coil comes off, the operation of the capacitor charging circuit can be reliably stopped when the charging voltage of the capacitor becomes a predetermined value or more. For this reason, it is possible to suppress the occurrence of problems such as heat generation of the capacitor charging circuit.

According to the third aspect of the present invention, as the electric resistance means, the electric current flowing between the anode and the cathode of the thyristor, which is provided in the capacitor discharge circuit,
It is desirable to employ at least one or more fixed resistors having a constant electric resistance value that can be controlled to be equal to or less than a predetermined current value required for the thyristor to continue operating.

According to the fourth aspect of the present invention, a power transistor for interrupting the current on the primary side of the transformer is provided in the capacitor charging circuit, and as a charging operation stopping means, when the charging voltage of the capacitor is equal to or higher than a predetermined value, A semiconductor switching element for interrupting a base current of the power transistor is provided. According to the fifth aspect of the present invention, there is provided the arithmetic processing circuit for outputting a gate signal corresponding to the optimum ignition timing calculated based on the operating state of the internal combustion engine to the gate of the thyristor. Further, according to the invention described in claim 6, the capacitor charging circuit converts the DC oscillated by the oscillator into a pulse current, and then boosts the AC to a predetermined voltage by a transformer, and uses the AC of the predetermined voltage as a power supply to the capacitor. It is a DC-DC converter to be charged.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Structure of Embodiment] An embodiment of the present invention will be described based on an embodiment with reference to the drawings. here,
FIG. 1 is a diagram showing a basic circuit of a capacitive discharge ignition device for a two-wheeled vehicle.

The capacity discharge type ignition device for a two-wheeled vehicle according to this embodiment is a CDI for a two-wheeled vehicle,
An ignition coil 2 for outputting ignition energy to
A basic circuit 3 of a battery ignition type CDI for interrupting the current on the primary side of the ignition coil 2 is provided.

A spark plug 1 is mounted on a cylinder head of a single-cylinder gasoline engine (internal combustion engine) for a two-wheeled vehicle, and fires from a secondary side of an ignition coil 2 once every two revolutions of a crankshaft of the engine. It ignites the air-fuel mixture sucked into the cylinder by receiving energy.

The ignition coil 2 has a secondary winding 12 and a primary winding 11 wound around a rod-shaped iron core (not shown).
Is a kind of transformer that generates the high voltage required for ignition in the secondary winding when the discharge current flows.

The basic circuit 3 includes a capacitor 4 connected to a DC power supply (battery) (not shown) via a transformer 20.
A thyristor 5 connected between the primary winding 11 of the ignition coil 2 and the capacitor 4, a capacitor charging circuit (hereinafter referred to as a DC-DC converter) 6 for charging the capacitor 4, and a thyristor 5 And an arithmetic processing circuit 8 that calculates an optimal ignition timing and outputs a gate signal to the thyristor 5 at a predetermined timing based on the optimal ignition timing.

The capacitor 4 is disposed in a charging circuit of the secondary coil 22 → the diode 14 → the capacitor 4 of the transformer 20, and charges (charges) a half wave of the AC waveform generated in the secondary coil 22. . As the thyristor 5, a unidirectional three-terminal thyristor is used, and the thyristor 5 has two gates.
The fixed resistors 15 and 16 and the capacitor 17 are connected, the anode is connected to the positive electrode side of the capacitor 4, and the cathode is connected to GND (earth) 40.

The DC-DC converter 6 converts a 12 V direct current into a pulse current by an oscillator 10 composed of a transistor 24, a power transistor 25, a fixed resistor 26, and the like. This circuit converts the alternating current into 250 volts, rectifies the alternating current by the diode 14, obtains a direct current of approximately 150 to 250 volts, and stores the direct current of approximately 150 to 250 volts in the capacitor 4. In addition, the DC-DC converter 6
Has a current-detecting fixed resistor (detection resistor) 27, a Zener diode 28, and the like.

The transformer 20 of the present embodiment includes a primary coil 2 connected to a battery via an ignition switch.
1 and a secondary coil 22 connected to the capacitor 4 via the diode 14. Further, the transformer 20 is provided with a tertiary coil 23 connected between the fixed resistor 29 and the GND 40. The transistor 24 has a base connected to the emitter of the power transistor 25 via the fixed resistor 26, a collector connected to the base of the power transistor 25, and an emitter
Connected to ND40.

The power transistor 25 includes a transformer 20
Is a semiconductor switching element for interrupting the current of the primary coil 21. The power transistor 25 has a base connected to the battery, a collector connected to the primary coil 21 of the transformer 20, and an emitter connected to the GND 40 via the detection resistor 27. Furthermore, the Zener diode 28 constitutes a transistor protection circuit that protects the power transistor 25 from overvoltage by bypassing the current when a voltage higher than the Zener voltage is applied between the collector and the emitter of the power transistor 25.

The capacitor discharge circuit 7 includes a capacitor 4 →
The thyristor 5 → GND 40 → primary winding 11 of the ignition coil 2 → capacitor 4 constitutes a circuit. Then, the capacitor discharge circuit 7 turns on the thyristor 5 by inputting a gate signal (ignition timing signal) to the thyristor 5 at a predetermined ignition timing, that is, conducts between the anode and the cathode of the thyristor 5, and turns on the capacitor 4. Is a circuit for discharging the electric charge stored in the ignition coil 2 to the primary winding 11 at a stretch.

The capacitor discharge circuit 7 of this embodiment
A fixed resistor 30 (corresponding to the electric resistance means of the present invention) 30 for detecting a capacitor charging voltage is connected to the ignition coil 2.
Are connected in parallel to the primary winding 11. The fixed resistor 30 has a current value flowing between the anode and the cathode of the thyristor 5 equal to or less than a predetermined current value required for the thyristor 5 to continue operating, that is, an electric resistance capable of turning the thyristor 5 OFF. Have a value. Here, the electric resistance value is desirably any one of 470 kΩ to 2.78 MΩ or less.

In this embodiment, the Zener diode (corresponding to the charging voltage detecting means of the present invention) 31 and the DC voltage are provided in the capacitor charging voltage detecting paths A and B for detecting the charging voltage of the capacitor 4. A transistor (corresponding to a charging operation stopping means of the present invention) 32 for stopping the operation of the DC converter 6; The transistor 32 has a base connected to the Zener diode 31, a collector connected to the battery, and an emitter connected to the GN.
D40. When a current flows through the base of the transistor 32, the base current of the power transistor 25 is cut off, and the operation of the DC-DC converter 6 is stopped. That is, charging of the capacitor 4 is stopped.

The Zener diode 31 is connected to the GND 40 connected through the primary winding 11 of the ignition coil 2.
The charging voltage of the capacitor 4 is detected with reference to FIG.
The charging voltage of the capacitor 4 is detected based on the capacitor charging voltage detection path A) of FIG. 1 or the GND 40 connected via the fixed resistor 30 (the capacitor charging voltage detection path B of FIG. 1). The Zener diode 31 is configured to supply a base current to the transistor 32 when the charging voltage of the capacitor 4 becomes equal to or higher than a predetermined value (Zener voltage).

Here, the capacitor charging voltage detection path A in FIG. 1 is a voltage detection path of GND 40 → primary winding 11 of the ignition coil 2 → capacitor 4 → zener diode 31 → transistor 32. The capacitor charging voltage detection path B in FIG. 1 is defined as GND 40 → fixed resistor 30 → capacitor 4 → Zener diode 31 →
This is a voltage detection path of the transistor 32.

The arithmetic processing circuit 8 calculates an optimum ignition timing (ignition timing) in accordance with the crank angle signal from the crank angle sensor 9, and sends an ignition timing signal (gate signal) to the thyristor 5 of the capacitor discharge circuit 7. Output. Here, the crank angle signal from the crank angle sensor 9 is formed into a pulse waveform by the arithmetic processing circuit 8 and then input to the gate of the thyristor 5 via the fixed resistor 15.

Next, the operation of the CDI ignition system for a two-wheeled vehicle according to this embodiment will be briefly described with reference to FIGS. Here, FIG. 2 is a timing chart showing voltage waveforms at respective detection points (a to f) during normal operation.

When an ignition switch (not shown) is closed, a base current flows from the battery to the power transistor 25, so that the power transistor 25 is turned on.
A current flows in the order of battery → primary coil 21 of transformer 20 → power transistor 25 → detection resistor 27 → GND40. Then, a base current flows to the transistor 24 via the fixed resistor 26, so that the transistor 2
4 turns ON, battery → transistor 24 → GND40
A current flows as follows.

As a result, the base current of the power transistor 25 is cut off, and the power transistor 25
FF is performed. By repeating this, the DC voltage of 12 V is changed to a pulse waveform as shown in FIG. As a result, the primary current of the transformer 20 is interrupted, so that about 150 to 250 V
Is converted to an AC voltage. The AC is rectified by the diode 14 to obtain a DC of about 150 to 250 V, and the DC of about 150 to 250 V is charged in the capacitor 4.
That is, the DC-DC converter 6 operates to charge the capacitor 4.

When the ignition coil 2 is not disconnected, as shown in the capacitor charging voltage detection path A in FIG. 1, the GND 40 connected through the primary winding 11 of the ignition coil 2 is used as a reference. The charging voltage of the capacitor 4 is applied to the Zener diode 31. Then, as shown in FIG. 2A, when the charging voltage of the capacitor 4 becomes a voltage equal to or higher than a predetermined value (Zener voltage: 175 V, for example), the Zener diode 31
A base current flows through the transistor 32 to turn on the transistor 32 (see FIG. 2C).

Thereby, the battery → transistor 3
Since a current flows as 2 → GND40, the base current of the power transistor 25 is cut off and the power transistor 25 is turned off. That is, as shown in FIG. 2F, the operation of the DC-DC converter 6 is stopped, and the charging of the capacitor 4 ends.

Then, as shown in FIG. 2D, an ignition timing signal (gate signal) having a pulse waveform is input from the arithmetic processing circuit 8 to the gate of the thyristor 5 via the fixed resistor 15 at the optimum timing. Then, the thyristor 5 operates (turns on) and the anode-cathode of the thyristor 5 is turned on. As a result, the electric charge charged in the capacitor 4 is transferred to the positive electrode side of the capacitor 4 → the thyristor 5 → GND 40 → the primary winding 1 of the ignition coil 2.
1 → Capacitor discharge circuit 7 on the negative side of capacitor 4
Is discharged at once.

At this time, while the negative voltage shown in FIG. 2A and the positive voltage shown in FIG. 2E are generated, the charge of the charged capacitor 4 is transferred to the primary winding 11 of the ignition coil 2. It will discharge. This allows
Since a high voltage is generated in the secondary winding 12 of the ignition coil 2, a spark discharge is generated between the center electrode and the ground electrode of the spark plug 1, and the air-fuel mixture sucked into the cylinder of the internal combustion engine is ignited. Is done.

The Zener diode 31 is arranged as shown in FIG.
As shown in (a), when the charging voltage of the capacitor 4 becomes lower than a predetermined value (zener voltage: 175 V, for example), the base current of the transistor 32 is cut off.
The transistor 32 is turned off (see FIG. 2C). As a result, the DC-DC converter 6 operates again to start charging the capacitor 4.

FIG. 3 is a timing chart showing voltage waveforms at the respective detection points (a to f) when the ignition coil is detached. In this embodiment, the basic circuit (product) of the battery ignition type CDI is used.
By inserting the fixed resistor 30 into the ignition coil 3, the charging voltage of the capacitor 4 is detected even if the ignition coil 2 comes off, and a predetermined voltage (zener voltage: for example, 175)
V), the charging of the capacitor 4 is stopped. However, the following effects appear depending on the electric resistance value of the fixed resistor 30.

B) When the electric resistance value of the fixed resistor 30 is low, for example, several tens of ohms or less, during normal operation,
That is, when the ignition coil 2 has not come off, the current flows too much through the fixed resistor 30 and the current in the primary winding 11 of the ignition coil 2 decreases, and as shown in the graph of FIG. There is a problem that the voltage becomes low and the ignition performance of the ignition coil 2 is adversely affected.

B) When the electric resistance of the fixed resistor 30 is high, for example, several MΩ or more, as shown in the graph of FIG. Since the base current of the transistor 32 for stopping the charging of the capacitor 4 is insufficient, the transistor 32 cannot be turned on, and the charging of the capacitor 4 cannot be stopped. Not detectable.

C) When the electric resistance of the fixed resistor 30 is a medium resistance value, for example, several hundred kΩ or more, when the ignition coil 2 is disconnected and a rotation signal is input (precondition). ), Since the discharging is performed by the fixed resistor 30, the discharging time is long. In addition, as a characteristic of the thyristor 5, when a current equal to or more than a predetermined current value flows between the anode and the cathode, the thyristor 5 keeps ON regardless of the presence or absence of the gate signal.

Due to the characteristics of the thyristor 5, a forced OFF time for charging the capacitor 4 is ensured. However, when the fixed resistor 30 is used for discharging, the discharging time becomes longer, and O
Since the current of the thyristor 5 continues to flow even after the FF time, the thyristor 5 cannot be turned off, and the charge stored in the capacitor 4 flows through the thyristor 5, so that the charging voltage of the capacitor 4 does not increase. Transformer 2
0 continues to operate (see f in FIG. 3).

[Effects of the Embodiment] Therefore, in this embodiment, the current flowing through the thyristor 5 is set to an electric resistance value (for example, 470 kΩ to less than a predetermined current (holding current)).
By selecting 2.78 MΩ), the above a) and
The disadvantages b) and c) can be solved.

Also, when the ignition coil 2 comes off, for example, when the wire harness is abnormal, the primary winding 11 of the ignition coil 2 is broken, or the product of the ignition coil 2 is GND, the fixed resistor 30 is used. Capacitor 4 based on connected GND 40
(See capacitor charge voltage detection path B in FIG. 1).

Therefore, the operation of the oscillator 10 such as the power transistor 25 can be stopped when the charging voltage of the capacitor 4 becomes equal to or higher than a predetermined value (zener voltage: 270 V, for example).
Can be reliably stopped. For this reason, D
Problems such as heat generation of the C-DC converter 6, especially the transformer 20, and the power transistor 25 can be prevented.

[Modification] In this embodiment, as the electric resistance means, a fixed resistor 30 having an electric resistance value (for example, 470 kΩ to 2.78 MΩ) capable of turning off the thyristor 5 is used as a product (two-wheeled vehicle). Although it is included in the basic circuit 3) of the capacity discharge ignition device for use, particularly in the capacitor discharge circuit 7, as an electric resistance means, a variable resistor whose electric resistance can be changed from, for example, 470 kΩ to 2.78 MΩ, or The resistance value is, for example, 470 kΩ to 2.78.
A resistance element such as a heating element, a light emitting element, and a coil of MΩ may be put in the product, particularly in the capacitor discharge circuit 7.

In this embodiment, the oscillator 10 of the DC-DC converter 6 is constituted by the transistor 24, the power transistor 25, the fixed resistor 26 and the like.
-The oscillator 10 of the DC converter 6 may be constituted by another oscillator. Further, the fixed resistor 29 and the tertiary coil 23 may not be provided.

In this embodiment, the ignition timing signal from the arithmetic processing circuit 8 is input to the gate of the thyristor 5. However, the gate of the thyristor 5 receives the signal from the engine ECU including the function of the microcomputer. You may comprise so that an ignition timing signal may be input.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a basic circuit of a capacitive discharge ignition device for a two-wheeled vehicle (Example).

FIG. 2 is a timing chart showing voltage waveforms at respective detection points during normal operation (Example).

FIG. 3 is a timing chart showing a voltage waveform at each detection point when an ignition coil comes off (Example).

FIG. 4 is a graph showing a relationship between a primary voltage of an ignition coil and an electric resistance value of a fixed resistor (Example).

FIG. 5 is a graph showing a relation between a base current of a transistor and an electric resistance value of a fixed resistor (Example).

FIG. 6 is a circuit diagram showing a basic circuit of a capacitive discharge ignition device (prior art).

[Explanation of symbols]

 A capacitor charging voltage detection path B capacitor charging voltage detection path 1 spark plug 2 ignition coil 3 basic circuit of battery ignition type CDI 4 capacitor 5 thyristor 6 DC-DC converter (capacitor charging circuit) 7 capacitor discharging circuit 11 primary winding 12 2 Next winding 20 Transformer 31 Zener diode (charging voltage detecting means) 32 Transistor (charging operation stopping means)

Claims (6)

[Claims] (A) an ignition coil having a secondary winding and a primary winding wound thereon; (b) a capacitor charging circuit for boosting a voltage of a DC power supply by a transformer to charge a capacitor; A thyristor connected between a primary winding of an ignition coil and the capacitor; (d) operating the thyristor at a predetermined ignition timing;
A capacitor discharge circuit for discharging the electric charge stored in the capacitor to a primary winding of the ignition coil; and (e) an electric resistance means connected in parallel to the primary winding of the ignition coil and having a predetermined electric resistance value (F) charging voltage detecting means for detecting the charging voltage of the capacitor with reference to the ground connected via the primary winding of the ignition coil or the ground connected via the electric resistance means. -Capacity discharge ignition device equipped. 2. The charging operation according to claim 1, wherein the operation of the capacitor charging circuit is stopped when the charging voltage of the capacitor detected by the charging voltage detecting means is equal to or higher than a predetermined value. A capacity discharge type ignition device comprising a stopping means. 3. A igniter according to claim 1, wherein said electric resistance means is disposed in said capacitor discharge circuit and flows between an anode and a cathode of said thyristor. At least one or more fixed resistors having a constant electric resistance value capable of controlling a current value to be equal to or less than a predetermined current value required for the thyristor to continue operating. Capacity discharge ignition device. 4. The capacitive discharge ignition device according to claim 1, wherein the capacitor charging circuit has a power transistor for interrupting a current on a primary side of the transformer, and The operation-disabling means is a semiconductor switching element that cuts off a base current of the power transistor when a charging voltage of the capacitor is equal to or higher than a predetermined value. 5. A capacity discharge type ignition device according to claim 1, wherein an operating state detecting means for detecting an operating state of the internal combustion engine, and an internal combustion detected by the operating state detecting means. An arithmetic processing circuit that calculates an optimal ignition timing based on an operating state of the engine, wherein the arithmetic processing circuit outputs a gate signal corresponding to the optimal ignition timing to a gate of the thyristor. Capacity discharge ignition device. 6. The capacitive discharge ignition device according to claim 1, wherein said capacitor charging circuit is a DC-DC converter.