JPH08121307A - Ignition device for internal combustion engine of condenser charge and discharge system - Google Patents

Abstract

PURPOSE: To prevent a change of lag characteristics due to a change of the induced voltage of an exciter coil by charging a charge and discharge condenser in the positive half cycle of the induced voltage which is induced to the exciter coil, and charging a condenser for a trigger by means of the charged voltage. CONSTITUTION: A condenser 11 for a trigger is charged by the charged voltage VC of a charge and discharge condenser 7 under such a condition that a switching transistor 14 is switched on in the positive half cycle of the induced voltage VS of an exciter coil 1, and a resistor 13 for partial pressure is connected in parallel to the condensor 11 for the trigger of a time constant circuit 12. Meanwhile, the switching transistor 14 is switched off during a negative half cycle period and the resistor 13 for the partial pressure is separated from the condensor 11 for the trigger, so that the condensor 11 for the trigger is charged by the charged voltage VC of the charge and discharge condensor 7. And, a thyristor 8 for discharge control is triggered by the voltage VA of the condensor 11 for the trigger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor charge / discharge type ignition device for an internal combustion engine.

[0002]

2. Description of the Related Art A condenser charging / discharging type ignition device is widely used in a brush cutter, an internal combustion engine mounted on a chainsaw, an internal combustion engine mounted on a small motorcycle, and the like. This capacitor charging / discharging type ignition device is conventionally known, for example, in Japanese Examined Patent Publication No. Sho 62-30301, Japanese Utility Model Publication No. 5-458.
As described in Japanese Patent No. 24, the ignition timing is automatically delayed when the rotational speed of the internal combustion engine becomes high in order to prevent the internal combustion engine from excessively rotating when there is no load on the brush cutter or the like. There is something I did.

That is, a conventional ignition device is provided with an exciter coil which is provided in a magnet type generator of an internal combustion engine and induces a voltage corresponding to the rotational speed of the internal combustion engine, and a positive half cycle of the induced voltage of the exciter coil. A charging / discharging capacitor to be charged, a discharge control thyristor for discharging the charge of the charging / discharging capacitor to the primary side of the ignition coil when turned on, and an ignition timing of the ignition coil by controlling the trigger timing of the discharge control thyristor. And an ignition timing control circuit for controlling the ignition timing.

The ignition timing control circuit is configured to trigger the discharge control thyristor in a negative half cycle of the induced voltage of the exciter coil to turn on the discharge control thyristor. , The ignition timing control circuit delays the ignition timing of the ignition coil,
It is designed to prevent the excessive rotation.

[0005]

In this conventional ignition device, the induced voltage of the exciter coil, especially the negative voltage thereof, is directly utilized to provide a trigger signal to the discharge control thyristor by the ignition timing control circuit. Therefore, there is a problem that the magnitude of the induced voltage of the exciter coil directly affects the retard angle characteristic.

That is, in the magnet type generator, the induced voltage induced in the exciter coil is caused by the air gap between the rotor and the stator, the temperature change, the flying state of the ignition coil, the magnetic flux change due to the material of the cover of the internal combustion engine, and the like. The voltage waveform may change greatly or slightly. For this reason,
In the conventional ignition device that directly uses the negative voltage induced in the exciter coil, the change in the waveform of the induced voltage immediately affects the retarding characteristic for preventing over-rotation, and there is a problem that the internal combustion engine over-rotates. is there.

Further, the conventional ignition device has a drawback that the structure of the ignition timing control circuit itself is very complicated, the number of parts is very large, and the manufacturing cost is increased. In view of such conventional problems, the present invention provides a capacitor charge / discharge type internal combustion engine ignition device capable of preventing a change in retardation characteristics due to a change in an induced voltage of an exciter coil, and having a reduced number of parts and a reduced manufacturing cost. The purpose is to do.

[0008]

The present invention is directed to an exciter coil 1 for inducing a voltage according to the number of revolutions of an internal combustion engine, and charging / discharging charged by a positive half cycle of an induced voltage V _S of the exciter coil 1. Capacitor 7 and the charge of the charging / discharging capacitor 7 when turned on, the primary winding of the ignition coil 2
The discharge control thyristor 8 to be discharged to 3 and the ignition coil 2 by controlling the trigger timing of this discharge control thyristor 8.
In a capacitor charging / discharging type internal combustion engine ignition device including an ignition timing control circuit 9 for controlling the ignition timing θ of the above, the ignition timing control circuit 9 is charged by the charging voltage V _C of the charging / discharging capacitor 7 and discharged. A time constant circuit 12 having a trigger capacitor 11 for triggering the control thyristor 8, a voltage dividing resistor 13 connected in parallel with the trigger capacitor 11 of the time constant circuit 12, and a series connection to the voltage dividing resistor 13. And a switching element 14 which is turned on at the positive half cycle of the induced voltage V _S of the exciter coil 1.

[0009]

When the induced voltage V _S is induced in the exciter coil 1, the charging / discharging capacitor 7 is charged in the positive half cycle of the induced voltage V _S , and the switching element 14 is turned on during this positive half cycle, and With the voltage dividing resistor 13 connected in parallel to the trigger capacitor 11 of the constant circuit 12, the charging resistor 10 is charged by the charging voltage V _C of the charging / discharging capacitor 7.
The trigger capacitor 11 is charged via.

When the internal combustion engine is in a predetermined rotation range or less, the discharge control thyristor 8 is triggered by the voltage V _A of the trigger capacitor 11 while the switching element 14 is on, and the discharge control thyristor 8 is supplied. The charge of the charging / discharging capacitor 7 is discharged to the primary winding 3 of the ignition coil 2.

On the other hand, in the high-speed rotation range of the internal combustion engine, the discharge control thyristor 8 is not triggered while the switching element 14 is on, and the switching element 14 is off to disconnect the voltage dividing resistor 13 from the trigger capacitor 11. After charging the trigger capacitor 11 with the charging voltage V _C of the charging / discharging capacitor 7 via the charging resistor 10, the voltage V _A of the trigger capacitor 11 triggers the discharge control thyristor 8 to ignite the ignition timing. The angle θ is retarded to prevent excessive rotation of the internal combustion engine.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In FIG. 1, 1 is an exciter coil, and this exciter coil 1 is wound around the stator side of a magnet type generator installed in an internal combustion engine. The magnet generator includes a rotor in which a permanent magnet is embedded in a flywheel mounted on a crankshaft of an internal combustion engine, and a stator mounted on a fixed side of the engine body or the like facing the rotor. A voltage corresponding to the rotation speed of the internal combustion engine is induced at both ends of the exciter coil 1 wound around the stator side.

An ignition coil 2 is provided with a primary winding 3 and a secondary winding 4, and an ignition plug 5 is connected to the secondary winding 4. 6 is a rectifying diode and 7 is a charging / discharging capacitor. These are the induced voltage V of the exciter coil 1.
The positive side winding of the exciter coil 1 and the ignition coil 2 in this order from the exciter coil 1 side to the rectifying diode 6 and the charge / discharge capacitor 7 so that the charge / discharge capacitor 7 is charged by the positive half cycle of _S. Connected in series with line 3.

Reference numeral 8 denotes a discharge control thyristor for discharging the electric charge of the charging / discharging capacitor 7 to the primary winding 3 of the ignition coil 2 when turned on, and the anode side is provided between the rectifying diode 6 and the charging / discharging capacitor 7. It is connected. 9 controls the trigger timing of the discharge control thyristor 8 to control the ignition coil 2
Is an ignition timing control circuit for controlling the ignition timing θ of the.

The ignition timing control circuit 9 includes a time constant circuit 12 in which a charging resistor 10 and a trigger capacitor 11 are connected in series,
The voltage dividing resistor 13 connected in parallel to the trigger capacitor 11 of the time constant circuit 12, and the switching which is connected in series to the voltage dividing resistor 13 and is turned on when the induced voltage V _S of the exciter coil 1 is positive half cycle. And a transistor 14.

In the time constant circuit 12, the charging resistor 10 side is connected between the rectifying diode 6 and the charging / discharging capacitor 7, and the middle point between the charging resistor 10 and the trigger capacitor 11 is for discharging control. The trigger capacitor 11 connected to the gate of the thyristor 8 is charged by the charging voltage V _C of the charging / discharging capacitor 7 via the charging resistor 10, and the voltage V _{A at} the midpoint of the discharging control thyristor 8. Trigger voltage V
_{When it reaches T} , the discharge control thyristor 8 is triggered.

The resistance ratio between the charging resistor 10 and the voltage dividing resistor 13 is such that the voltage V _A at the midpoint when the switching transistor 14 is on is the trigger voltage V _T of the discharge control thyristor 8.
Is set to be The collector of the switching transistor 14 is connected to the voltage dividing resistor 13. The base of the switching transistor 14 is connected to the middle point of a bias circuit 17 in which a resistor 15 and a diode 16 are connected in series, and the bias circuit 17 is connected between both ends of the exciter coil 1.

Next, the operation of this ignition device will be described. When the crankshaft of the internal combustion engine rotates and the magnet type generator operates, an induced voltage V _S having a voltage waveform as shown in FIG. 2A is induced at both ends of the exciter coil 1. And
During the positive half cycle of the induced voltage V _S , the charging / discharging capacitor 7 is charged via the rectifying diode 6. At this time, the charging voltage V _C of the charging / discharging capacitor 7 is charged to the peak voltage of the positive half cycle of the induced voltage V _S as shown in FIG. 2B.

On the other hand, during the positive half cycle of the induced voltage V _S , the base of the switching transistor 14 is biased by the bias circuit 17 including the resistor 15 and the diode 16, so that the switching transistor 14 is shown in FIG. Thus, it is turned on only during the positive half cycle of the induced voltage V _S.

When the switching transistor 14 is turned on, if the trigger capacitor 11 of the time constant circuit 12 is not present, the charging voltage V _C of the charging / discharging capacitor 7 is divided by the charging resistor 10 and the voltage dividing resistor 13. Therefore, the voltage V _{A at} the midpoint between the two is V _A = R as shown in FIG.
₂ · V _c / R ₁ + R ₂ (provided that the resistance value of the charging resistor 10 is R ₁ and the resistance value of the voltage dividing resistor 13 is R ₂ ).

However, at this time, since the trigger capacitor 11 is connected in series to the charging resistor 10 in the time constant circuit 12, and the voltage dividing resistor 13 is connected in parallel to the trigger capacitor 11, According to the time constant determined by the charging resistor 10 and the trigger capacitor 11, the charging / discharging capacitor 7
The trigger capacitor 11 is charged by the charging voltage V _C of the above, and the rise of the voltage V _{A at} the middle point is delayed as shown in FIG. And the voltage V at this midpoint
_A rises to a voltage obtained by dividing the charging voltage V _C of the charging / discharging capacitor 7 by the resistance ratio of the charging resistor 10 and the voltage dividing resistor 13.

The switching transistor 14 has an induced voltage V
_When the positive half cycle of _S is turned on for the period T _{1 and} the positive half cycle of the induced voltage V _S ends, the switching transistor 14 turns off at the end. Therefore, after the positive half cycle period of the induced voltage V _S, the voltage dividing resistor 13 is disconnected from both ends of the trigger capacitor 11, so that the trigger capacitor 11 is substantially equal to the charging voltage V _C of the charging / discharging capacitor 7. It will be charged to the same voltage. The charging time at this time is determined by the time constant of the charging resistor 10 and the trigger capacitor 11.

Revolving speed of internal combustion engine and charge / discharge capacitor 7
As shown in FIG. 3, the charging voltage V _C of the charging voltage V _C of the internal combustion engine rises as the rotation speed of the internal combustion engine increases, and the charging voltage V _C of the internal combustion engine increases in the high speed rotation region. The charging voltage V _C gradually decreases as the rotation speed increases. That is, the charging voltage V of the charging / discharging capacitor 7
_C changes parabolically in response to changes in the number of revolutions. Therefore, the voltage V _{A at} the midpoint of the time constant circuit 12 also changes parabolic as shown in FIG.

Therefore, during the ON period T ₁ of the switching transistor 14, the charging voltage V _C of the charging / discharging capacitor 7 is
Is divided by a charging resistor 10 and a voltage dividing resistor 13 to obtain a midpoint voltage V _A, which is a trigger voltage V of the discharge control thyristor 8.
If it is set to _T , the charging voltage V _C of the charging / discharging capacitor 7 rises as the rotation speed of the internal combustion engine rises below a predetermined rotation range such as the low speed and the medium speed rotation range of the internal combustion engine. Since the midpoint voltage V _A also rises, the timing at which the midpoint voltage V _A rises to the trigger voltage V _T is substantially constant, as shown in FIG. 2 (E).

When the voltage V _{A at the} midpoint rises to the trigger voltage V _T , the discharge control thyristor 8 is triggered and turned on, and the charge of the charging / discharging capacitor 7 passes through the discharge control thyristor 8 and the ignition coil. Since the secondary winding 3 of 2 is rapidly discharged, a high voltage is generated in the secondary winding 4 of the ignition coil 2 and a spark is generated in the spark plug 5.

Therefore, during the ON period T ₁ of the switching transistor 14, a spark is generated at the ignition plug 5 at the regular ignition timing θ, and the spark position is substantially constant. But,
When the rotation speed of the internal combustion engine rises to a high speed range, the charging voltage V _C of the charging / discharging capacitor 7 drops and the voltage _{VA at the} midpoint also drops. Therefore, the ON period T _{1 of the} switching transistor 14 In the middle, the voltage V _{A at} the middle point does not rise to the trigger voltage V _T of the discharge control thyristor 8 as shown in FIG.

Then, when the switching transistor 14 is in the OFF period T ₂ , the voltage dividing resistor 13 is disconnected from both ends of the trigger capacitor 11, so that the trigger capacitor is
11 is charged by a time constant determined by the charging resistor 10 and the trigger capacitor 11, and the voltage V _A at the midpoint exceeds the trigger voltage V _T of the discharge control thyristor 8 and the charge voltage V V of the charge / discharge capacitor 7. Since the voltage rises to near _C , the discharge control thyristor 8 is triggered and turned on when the midpoint voltage V _A rises to the trigger voltage V _T.

That is, in the high speed rotation range of the internal combustion engine, the trigger timing of the discharge control thyristor 8 moves from the ON period T ₁ of the switching transistor 14 in the medium speed rotation range to the OFF period T ₂ of the switching transistor 14, Delay the trigger time of thyristor 8 for discharge control. Then, in this off period T ₂ , the discharge control thyristor 8 is triggered and turned on, and the charge of the charging / discharging capacitor 7 is discharged to the primary winding 3 of the ignition coil 2. Therefore, as shown in FIG. In the high speed rotation range, the ignition timing θ of the spark plug 5 can be rapidly retarded.

At this time as well, the trigger timing is substantially constant at the time determined by the time constants of the charging resistor 10 and the charging / discharging capacitor 7. Then, the ignition timing θ is abruptly retarded with the increase of the rotation speed of the internal combustion engine, and it is possible to prevent the internal combustion engine from excessively rotating when the brush cutter is not loaded.

As described above, in this embodiment, the switching transistor 14 is turned on in the positive half cycle of the induced voltage V _S of the exciter coil 1, and the voltage dividing resistor 13 is connected in parallel to the trigger capacitor 11 of the time constant circuit 12. While charging the trigger capacitor 11 with the charging voltage V _C of the charge / discharge capacitor 7, the switching transistor 14 is turned off during the negative half cycle to disconnect the voltage dividing resistor 13 from the trigger capacitor 11. The configuration is adopted in which the trigger capacitor 11 is charged by the charging voltage V _C of the charge / discharge capacitor 7, and the voltage V of the trigger capacitor 11 is
_{Since the} discharge control thyristor 8 is triggered by _A , the induced voltage of the exciter coil 1 is compared with the conventional case where the negative voltage of the induced voltage V _S is directly used to trigger the discharge control thyristor 8. Even if the voltage waveform of V _S changes, the change does not greatly affect the trigger timing of the discharge control thyristor 8, and the change of the retard angle characteristic due to the change of the induced voltage V _S of the exciter coil 1 is prevented. You can

Further, the retard characteristic can be easily and arbitrarily selected and set by changing the time constant of the charging resistor 10 and the trigger capacitor 11 of the time constant circuit 12. Further, the ignition timing control circuit 9 has a time constant circuit 12 having a trigger capacitor 11 that is charged by the charging voltage V _C of the charge / discharge capacitor 7 and triggers the discharge control thyristor 8, and a trigger for this time constant circuit 12. Capacitors
A voltage dividing resistor 13 connected in parallel with 11 and this voltage dividing resistor
Since the switching transistor 14 is connected to 13 in series and is turned on at the positive half cycle of the induced voltage V _S of the exciter coil 1, the overall circuit configuration is simple and the number of parts is small. By comparison, the manufacturing cost can be significantly reduced.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, although the switching transistor 14 is used as the switching element in the embodiment, an element other than the switching transistor 14 may be used. Further, the present invention can be used as a means for limiting the maximum vehicle speed when it is used for an internal combustion engine mounted on a two-wheeled vehicle such as a bicycle and a motorcycle. In addition, other control functions can be freely added without changing the gist of the present invention.

[0033]

According to the present invention, an exciter coil 1 for inducing a voltage corresponding to the rotational speed of an internal combustion engine, and a charging / discharging capacitor charged by a positive half cycle of the induced voltage V _S of the exciter coil 1 are used. 7, a discharge control thyristor 8 that discharges the charge of the charging / discharging capacitor 7 to the primary coil 3 of the ignition coil 2 when turned on, and the trigger timing of the discharge control thyristor 8 is controlled to control the ignition coil 2 In an ignition device for a capacitor charging / discharging type internal combustion engine, which comprises an ignition timing control circuit 9 for controlling the ignition timing θ, the ignition timing control circuit 9 is charged by a charging voltage V _C of a charging / discharging capacitor 7 and discharge control is performed. Time constant circuit 12 having a trigger capacitor 11 for triggering the thyristor 8, a voltage dividing resistor 13 connected in parallel with the trigger capacitor 11 of the time constant circuit 12, and a voltage dividing resistor 13 Since a switching element 14 which is turned positive during a half cycle of the column connected to and exciter induced voltage V _S of the motor coil 1 can prevent a change in the retard characteristics due to a change in the induced voltage V _S of the exciter coil 1 In addition, there is an advantage that the over-rotation of the internal combustion engine can be surely prevented and the number of parts is small and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an ignition circuit showing an embodiment of the present invention.

FIG. 2 is a waveform diagram showing an embodiment of the present invention.

FIG. 3 is a voltage waveform diagram showing an embodiment of the present invention.

FIG. 4 is a delay angle characteristic diagram showing an embodiment of the present invention.

[Description of sign]

 1 Exciter coil 2 Ignition coil 6 Rectifying diode 7 Charging / discharging capacitor 8 Discharge control thyristor 9 Ignition timing control circuit 10 Charging resistor 11 Trigger capacitor 12 Time constant circuit 13 Dividing resistor 14 Switching transistor (switching element)

Claims (3)

[Claims] 1. An exciter coil (1) for inducing a voltage according to the rotational speed of an internal combustion engine, and the exciter coil (1).
Charging / discharging capacitor (7) that is charged by the positive half cycle of the induced voltage V _S of
The discharge control thyristor (8) that discharges the electric charge of (7) to the primary winding (3) of the ignition coil (2) and the ignition timing by controlling the trigger timing of this discharge control thyristor (8) 2) In a capacitor charging / discharging type internal combustion engine ignition device equipped with an ignition timing control circuit (9) for controlling the ignition timing θ, the ignition timing control circuit (9) charges the charging / discharging capacitor (7). A time constant circuit (1) having a trigger capacitor (11) that is charged by a voltage V _C and triggers a discharge control thyristor (8)
2), the voltage dividing resistor (13) connected in parallel to the trigger capacitor (11) of this time constant circuit (12), and this voltage dividing resistor (1
A switching element connected in series to 3) and turned on when the positive voltage half cycle of the induced voltage V _S of the exciter coil (1)
(14) A capacitor charging / discharging type ignition device for an internal combustion engine, comprising: 2. An exciter coil (1) and an ignition coil (2)
The rectifying diode (6) and the charging / discharging capacitor (7) are connected between the primary winding (3) of the
Connect the discharge control thyristor (8) and the time constant circuit (12) between the charge and discharge capacitor (6) and the time constant circuit.
The capacitor charging / discharging type internal combustion engine according to claim 1, wherein a series circuit of a voltage dividing resistor (13) and a switching element (14) is connected in parallel to the trigger capacitor (11) of (12). Ignition device. 3. A discharge control thyristor (8) between a charging resistor (10) and a trigger capacitor (11) of a time constant circuit (12).
3. The gate of is connected, and the ratio of the charging resistor (10) and the voltage dividing resistor (13) is set to the trigger voltage V _T of the discharge control thyristor (8). Capacitor charge / discharge type ignition device for internal combustion engine.