JPS6344946B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition system for an internal combustion engine that is equipped with an ignition position control circuit that delays the ignition position in a high speed range in order to prevent engine overspeed.

Conventionally, many internal combustion engine ignition devices equipped with a circuit to prevent engine overspeed have been used that stop ignition when the engine speed (rpm) reaches a set value. However, when the ignition operation is stopped, unburned gas is discharged, and hysteresis occurs where the rotation speed at which the overspeed prevention operation starts and the rotation speed at which the overspeed prevention operation is released do not match. . In particular, when hysteresis occurs, ignition is not restarted until the rotation speed drops below the set value, which can cause the spark plug to leak unburned gas and make ignition difficult.
It had the disadvantage of causing backfire. Therefore, a device was proposed that suppresses the increase in engine speed by delaying the ignition position when the engine speed reaches a set value. Since a pump-up circuit was used in the engine, there was a large response delay, and there was a drawback that accurate over-speed prevention operation could not be performed when the rotation speed suddenly increased or decreased.

An object of the present invention is to provide an ignition device for an internal combustion engine with an overspeed prevention circuit that does not discharge unburned gas, does not cause hysteresis in overspeed prevention operation, and reduces response delay. It is in.

The present invention provides a method for controlling the primary current of the ignition coil.
An ignition circuit that generates a high voltage for ignition by the operation of a semiconductor switch for controlling the next current, and an ignition circuit that induces an alternating current voltage in synchronization with the rotation of the internal combustion engine and provides ignition energy to the ignition circuit with the output of one half cycle. The exciter coil connected to the ignition circuit and the trigger signal input terminal of the primary current control semiconductor switch when the signal voltage generated in synchronization with the rotation of the internal combustion engine reaches a first threshold value. an ignition timing signal supply circuit that provides an ignition timing signal to perform an ignition operation; and an ignition control circuit that controls the operating position of the primary current control semiconductor switch to be delayed when the rotational speed of the internal combustion engine reaches a set value. An ignition device for an internal combustion engine comprising a position control circuit, a series circuit of a current limiting element and a retard thyristor connected in parallel between the trigger signal input terminals of the primary current control semiconductor switch; an ignition signal supply circuit that provides an ignition signal to the gate of the retard thyristor when the signal voltage reaches a second threshold lower than the first threshold; and a ignition signal supply circuit that charges at a constant time constant with the signal voltage. the ignition signal is given to the retard thyristor when the terminal voltage of the capacitor for determining the set rotation speed is less than a third threshold that is lower than the second threshold; and a retard thyristor control circuit that allows the set rotation speed determining capacitor to have a terminal voltage equal to or higher than the third threshold and prevents an ignition signal from being applied to the retard thyristor. The present invention is characterized in that the ignition position control circuit is configured.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, in which 1 is an ignition coil having a primary coil 1a and a secondary coil 1b, 2 is an ignition coil installed in a cylinder of an engine (not shown), and a secondary This is a spark plug connected to both ends of the coil 1b. One end of the primary coil 1a is connected to the anode of a diode 3 whose cathode is grounded, and the other end is connected to one end of a capacitor 4. The other end of the capacitor 4 is connected to the anode of a thyristor 5 as a primary current control semiconductor switch whose cathode is connected to the anode of the diode 3, and a resistor 6 is connected in parallel between the gate and cathode of the thyristor 5. Primary coil 1a
A diode 7 is connected in parallel to both ends of the ignition circuit 8 with its cathode facing the ground side, and a capacitor discharge type ignition circuit 8 is constituted by each of the above parts.

In order to provide ignition energy to the ignition circuit, an exciter coil 9 is provided in a magnet generator (not shown). This magnet generator is driven by the engine, and an alternating current voltage is induced in the exciter coil 9 in synchronization with the rotation of the engine. One end of the exciter coil 9 is grounded, and the other end is connected to the anode of the thyristor 5 through a diode 10. Therefore, the capacitor 4 is charged to the polarity shown through the diode 10 by the output voltage (hereinafter referred to as positive direction voltage) ν _e of the exciter coil 9 in one half cycle in the direction of the solid arrow shown in the drawing. In order to obtain a signal voltage for controlling the thyristor 5 from the output voltage (hereinafter referred to as negative direction voltage) ν _e ' of the other half cycle of the exciter coil 9 in the direction of the dashed arrow shown in the figure, a diode 11 whose anode is grounded is used. is provided, and a resistor 1 is connected to the cathode of this diode.
One end of 3 is connected. The other end of the resistor 13 is connected to the anode of a diode 14, and the cathode of the diode 14 is connected to the non-ground terminal of the exciter coil 9. Resistor 13 and diode 1
The connection point between the resistor 13 and the cathode of the diode 11 is connected to the cathode of the first Zener diode 15 whose anode is connected to the gate of the thyristor 5. .

The above diode 11, resistor 13, diode 1
4 and the first Zener diode 15 constitute an ignition timing signal supply circuit that supplies an ignition timing signal to the gate (trigger signal input terminal) of the thyristor (semiconductor switch for primary current control) 5 using the negative voltage of the exciter coil 9. has been done. That is, when a negative voltage is induced in the exciter coil 9, the exciter coil 9 → diode 1
A current flows along the path 1→resistor 13→diode 14→exciter coil 9, and a signal voltage V ₁ appears across the resistor 13. When this signal voltage V ₁ reaches a first threshold value corresponding to the Zener voltage V _z1 of the Zener diode 15, this Zener diode 1
An ignition timing signal is applied to the gate of thyristor 5 through 5, and thyristor 5 becomes conductive. As a result, the charge in the capacitor 4 is discharged through the thyristor 5 and the primary coil 1a, and a large current change occurs in the primary coil 1a. This current change causes a large magnetic flux change in the iron core of the ignition coil, and a high voltage for ignition is induced in the secondary coil 1b. This high voltage is applied to the ignition plug 2, a spark is generated in the ignition plug 2, and the engine is ignited.

An ignition position control circuit 16 is provided to control the ignition position of the engine to be delayed when the engine speed reaches a set value. This control circuit includes a series circuit of a variable resistor 17 as a current limiting element and a retard thyristor 18, and this series circuit is connected to the gate of the thyristor (semiconductor switch for primary current control) 5 through a Zener diode 15. It is connected in parallel between the cathodes (between the trigger signal input terminals). The cathode of the thyristor 18 is grounded through the diode 3, and a resistor 19 is connected in parallel between the gate and cathode of this thyristor. The anode of a second Zener diode 20 is connected to the gate of the thyristor 18, and the cathode of the Zener diode 20 is connected to the resistor 2.
1 to the non-grounded terminal of the resistor 13. Zener voltage of Zener diode 20
V _z2 is set lower than the Zener voltage V _z1 of the first Zener diode 15, and the signal voltage obtained across the resistor 13 from the resistor 21 and the Zener diode 20 is lower than the first threshold value.
An ignition signal supply circuit is configured to provide an ignition signal to the thyristor 18 when the threshold value (Zener voltage V _z2 ) is reached.

The gate of the thyristor 18 is also connected to the collector of a transistor 22 whose emitter is grounded through the diode 3.
A resistor 23 is connected in parallel between the base emitters of the two. Further, a series circuit of a variable resistor 24 for determining the set rotation speed and a capacitor 25 for determining the set rotation speed is connected in parallel to both ends of the resistor 13, and the signal voltage V ₁ obtained across the resistor 13 causes the variable resistor 24
The capacitor 25 is charged at a constant time constant through the capacitor 25. The cathode of a third Zener diode 26 is connected to the connection point between the capacitor 25 and the variable resistor 24, and the anode of the Zener diode 26 is connected to the base of the transistor 22. The Zener voltage V _z3 of the Zener diode 26 is set lower than the Zener voltage V _z2 of the second Zener diode 20, and the third Zener diode 26, the resistor 23, and the transistor 22 control the capacitor 25 for determining the set rotation speed.
When the terminal voltage of the third Zener diode 26 is lower than a third threshold value corresponding to the Zener voltage of the third Zener diode 26, an ignition signal is allowed to be given to the retard thyristor 18, and the terminal of the set rotation speed determining capacitor 25 A retard thyristor control circuit is configured to prevent an ignition signal from being applied to the retard thyristor 18 when the voltage exceeds a third threshold value. Further, the anode of a diode 27 whose cathode is connected to the anode of the thyristor 5 is connected to the connection point between the resistor 13 and the cathode of the diode 11.
When the thyristor 5 is turned on, the charge in the capacitor 25 is rapidly discharged through the variable resistor 24, the diode 27, and the thyristor 5.

Next, the operation of the ignition system will be explained with reference to FIGS. 2 and 3. When a positive voltage ν _e is generated in the exciter coil 9, the exciter coil 9 → diode 10 → capacitor 4 → diodes 7 and 1
The capacitor 4 is charged along the path from the next coil 1a to the exciter coil 9. Next, exciter coil 9
When a negative direction voltage ν _e ' is generated, the exciter coil 9 → diode 11 → resistor 13 → diode 1
A current flows through the path 4→exciter coil 9, and a signal voltage V ₁ appears across the resistor 13. Since this signal voltage V ₁ is applied to the capacitor 25 through the variable resistor 24, the capacitor 25 is charged to the polarity with a fixed time constant. If the engine speed N is less than the set value _Ns , as shown in Figure 2,
Signal voltage V ₁ and capacitor 2 at engine rotation angle θ _p
After the terminal voltage V ₂ of the third Zener diode ₂₆ rises, the terminal voltage V ₂ of the capacitor 25 first reaches the Zener voltage V _z3 of the third Zener diode 26 at an angle θ 1, and then at an angle θ _i the signal voltage V ₁ reaches the third Zener voltage V z3. The Zener voltage V _z1 of the Zener diode 15 of No. 1 is reached. Voltage at angle θ ₁
When V ₂ reaches the Zener voltage V _z3 , a base current flows through the transistor 22 , which turns on and prevents the ignition signal from entering the gate of the thyristor 18 . When the signal voltage V ₁ reaches the Zener voltage V _z1 at the angle θ _i , an ignition timing signal is input to the thyristor 5, and the thyristor 5 becomes conductive. Therefore, the electric charge in the capacitor 4 is discharged through the thyristor 5 and the primary coil 1a, and a high voltage for ignition is generated in the secondary coil 1b, thereby performing an ignition operation. The signal voltage increases as the engine speed increases.
Since the peak value of V ₁ becomes higher and its rise becomes faster, the angle at which the signal voltage V ₁ reaches the Zener voltage V _z1 advances, and the ignition position advances.

When the engine speed N exceeds the set value _Zs , the third
As shown in the figure, the terminal voltage of capacitor 25 V ₂
Since the signal voltage V ₁ reaches the Zener voltage V z2 of the second Zener diode ₂₀ at an angle θ _a whose phase is more advanced than the angle θ ₁ at which the signal voltage V 1 reaches the Zener voltage V _z3 ,
An ignition signal is applied to the thyristor 18, and the thyristor 18 becomes conductive. When the thyristor 18 becomes conductive, the variable resistor 17 is connected in parallel to the resistor 13, so that the signal voltage _V1 decreases. This signal voltage
V ₁ eventually reaches the Zener voltage V _z1 of the Zener diode 15 at an angle θ _i ', and the ignition operation takes place at this angle θ _i '. As mentioned above, since the signal voltage V ₁ decreases at the angle θ _a due to the conduction of the thyristor 18,
The angle (ignition position) θ _i ′ at which the signal voltage V ₁ reaches the Zener voltage V _z1 is the angle θ _i ″ at which the signal voltage V ₁ reaches the Zener voltage V _z1 when the thyristor 18 is not conductive at the angle θ _a Therefore, the characteristic of the ignition position with respect to the rotational speed N is that the ignition position is retarded in steps at the set rotational speed _Ns as shown in Fig. 4. The retardation suppresses the increase in engine speed and lowers it below the set value.
In the figure, TDC indicates the top dead center of the engine.

In the device of the present invention, the retard thyristor 1
By changing the resistance value of the current limiting element connected in series with 8, the amount of retardation at the set rotation speed can be adjusted, and by adjusting the charging time constant of the capacitor 25, the set value of the rotation speed can be changed. be able to. In the above embodiment, as shown by the broken line in FIG. 4, the amount of retardation can be increased by decreasing the resistance value R ₁₇ of the variable resistor 17, and the resistance value R ₂₄ of the variable resistor 24 can be increased. By decreasing the number of rotations, the set value _Ns of the rotation speed can be changed to a higher value. As described above, according to the present invention, it is possible to arbitrarily adjust the set value of the rotational speed at which the overspeed prevention operation is started and the amount of retardation of the ignition position. In the embodiment shown in FIG. 1, the capacitor 25
is rapidly discharged through the variable resistor 24, diode 27, and thyristor 5 when the thyristor 5 is conductive, so the capacitor 2 is discharged under the same conditions every cycle.
5 is repeated. Therefore, hysteresis does not occur, and the rotational speed at which the overspeed prevention operation is started can be matched with the rotation speed at which the overspeed prevention operation is released. Furthermore, since a pump-up circuit for detecting the rotational speed is not used, response can be improved, and accurate operation can be performed even when the rotational speed suddenly increases or decreases.
In addition, when detecting the rotation speed using a pump-up circuit as in the past, a first capacitor of relatively small capacity that is charged by the output of a coil that generates a voltage in synchronization with the rotation of the engine, and a A large-capacity second capacitor charged by the charge of the capacitor is required. In this way, conventional devices require two capacitors to detect rotational speed, and one of them requires a large capacity capacitor, which makes the device large and expensive. I couldn't help it. On the other hand, in the present invention,
One small capacity capacitor 25 for determining the set rotation speed
Since it is only necessary to provide a circuit, the circuit can be simplified, and the device can be made smaller and the cost can be reduced.

Next, FIG. 5 shows a second embodiment of the present invention, which differs from the embodiment shown in FIG. This is the point inserted between. Other configurations and operations are similar to the example shown in FIG.

FIG. 6 shows a third embodiment of the present invention, in which the ignition circuit 8 is constructed in the same manner as in FIG. 1 except that the cathode of the thyristor 5 is directly grounded. . A diode 28 with its anode facing the ground is connected in parallel between the gate and cathode of the thyristor 5, and one end of a capacitor 30 is connected to the gate of the thyristor 5 through a resistor 29. The other end of the capacitor 30 is connected to the cathode of a thyristor 31 whose anode is grounded, and a resistor 32 is connected in parallel between the gate and cathode of the thyristor 31. The anode and cathode of a first Zener diode 15 are connected to the gate and anode of the thyristor 31, respectively, and the diode 14 is connected to the cathode of the thyristor 31 and the non-grounded terminal of the exciter coil 9, respectively.
The anode and cathode of are grounded. Diode 28, resistor 29, capacitor 30, thyristor 31, resistor 32, Zener diode 15
The diode 14 constitutes an ignition timing signal supply circuit that provides an ignition timing signal to the thyristor 5. Resistor 13 is thyristor 31
is connected in parallel to both ends of the resistor 13, so that a signal voltage _V1 appears across both ends of this resistor 13. The ignition position control circuit 16 is configured similarly to the example shown in FIG.
The cathode of the thyristor 18 is connected to the cathode of the thyristor 31, and the anode of the thyristor 18 is connected to the variable resistor 17.
It is connected to the anode (ground) of the thyristor 31 through the thyristor 31.

In the embodiment shown in FIG. 6, when a negative direction voltage ν _e ' is generated in the exciter coil 9, the path of the exciter coil 9 → diode 28 → resistor 29 → capacitor 30 → diode 14 → exciter coil 9 and the exciter coil 9→Resistance 13→
A current flows through the path from the diode 14 to the exciter coil 9, and the capacitor 30 is charged to the polarity shown. As the charging of this capacitor 30 progresses, the signal voltage 13 obtained across the resistor 13 increases, and when this signal voltage V ₁ reaches the first threshold value, the Zener diode 15 becomes conductive and sends an ignition signal to the thyristor 31. enters. As a result, thyristor 3
1 is conductive, and the charge of the capacitor 30 is transferred to the resistor 29,
Discharge occurs between the gate and cathode of the thyristor 5 and through the thyristor 31. This discharge current provides an ignition timing signal for the thyristor 5, and an ignition operation is performed. Since the signal voltage V ₁ appearing across the resistor 13 is also applied to the capacitor 25 through the variable resistor 24, this capacitor 25
is charged with a fixed time constant. If the engine speed is less than the set value, the terminal voltage of the capacitor 25 will be lower than the Zener diode 2 before the signal voltage V ₁ reaches the level that makes the Zener diode 15 conductive.
Since the Zener voltage of 6 is reached and the transistor 22 is made conductive, the thyristor 18 is not conductive and no over-rotation prevention operation is performed. When the rotation speed exceeds the set value, the signal voltage V _{1 becomes equal to or higher than the Zener voltage of the Zener diode 20 before the terminal voltage V 2 of} the capacitor 25 reaches the Zener voltage of the Zener diode 26, so the thyristor 18 becomes conductive.
Over-rotation prevention operation is performed.

FIG. 7 shows a fourth embodiment of the present invention, in which a signal coil 35 is provided separately from the exciter coil 9.
The output of is applied to both ends of the resistor 13 via the diode 36. Further, the cathode of the thyristor 5 is directly grounded. The other configurations are similar to the example shown in FIG. In the example shown in FIG. 7, the signal coil 35 generates a signal voltage at a predetermined rotation angle position of the engine, and when this signal voltage reaches a first threshold value, the ignition timing is sent to the thyristor 5 through the Zener diode 15. A signal is given. Other operations are similar to the example shown in FIG.

In each of the above embodiments, a capacitor discharge type ignition circuit 8 is used, but the present invention can be widely applied to the case where an ignition circuit is used in which ignition energy is given by the half-wave output of the exciter coil 9. For example, a high voltage is induced in the exciter coil by cutting off the current flowing from the exciter coil through a semiconductor switch for primary current control at the ignition position.
The present invention can also be applied to the case where a cross-shaped ignition circuit is used in which this high voltage is further boosted by an ignition coil to obtain a high voltage for ignition.

As described above, according to the present invention, since there is no need to provide a rotation speed detection circuit using a pump-up circuit, response delay can be reduced, and even when the rotation speed suddenly increases or decreases, accurate over-rotation can be detected. A preventive action can be performed, and hysteresis does not occur in the over-speed preventive action. Furthermore, since no unburned gas is discharged, it is possible to prevent the spark plug from getting wet and from causing backfire.

[Brief explanation of the drawing]

1, 5, 6 and 7 are connection diagrams showing different embodiments of the present invention, FIGS. 2 and 3 are signal waveform diagrams explaining the operation of the present invention, and FIG. 4 1 is a diagram showing an example of the characteristics of the ignition position with respect to the rotational speed obtained by the present invention. 1...Ignition coil, 2...Spark plug, 4...
Capacitor, 5... Thyristor (semiconductor switch for primary current control), 9... Exciter coil, 1
1... Diode, 13... Resistor, 14... Diode, 15... Zener diode, 16...
Ignition position control circuit, 17... Variable resistor (current limiting means), 18... Retard thyristor, 20...
Zener diode, 22...transistor, 2
4... Variable resistor, 25... Capacitor for determining the set rotation speed, 26... Zener diode.

Claims (1)

[Scope of Claims] 1. An ignition circuit that generates a high voltage for ignition through the operation of a primary current control semiconductor switch that controls the primary current of an ignition coil, and an ignition circuit that generates an alternating current voltage in synchronization with the rotation of the internal combustion engine. an exciter coil connected to the ignition circuit to induce and provide ignition energy to the ignition circuit at the output of one half cycle;
Ignition timing for applying an ignition timing signal to a trigger signal input terminal of the primary current control semiconductor switch to perform an ignition operation when a signal voltage generated in synchronization with the rotation of the internal combustion engine reaches a first threshold value. An ignition device for an internal combustion engine, comprising a signal supply circuit and an ignition position control circuit that controls the operating position of the primary current control semiconductor switch to be delayed when the rotational speed of the internal combustion engine reaches a set value. The ignition position control circuit includes a series circuit of a current limiting element and a retard thyristor connected in parallel between the trigger signal input terminals of the primary current control semiconductor switch, and a series circuit in which the signal voltage is an ignition signal supply circuit that provides an ignition signal to the gate of the retard thyristor when a second threshold lower than the threshold of a capacitor, and a terminal voltage of the set rotation speed determining capacitor that allows the firing signal to be given to the retard thyristor when the terminal voltage of the capacitor for determining the set rotation speed is less than a third threshold value that is lower than the second threshold; The retard thyristor control circuit prevents an ignition signal from being applied to the retard thyristor when the terminal voltage of the determining capacitor exceeds the third threshold. Ignition system for internal combustion engines. 2. The ignition device for an internal combustion engine according to claim 1, wherein the signal voltage is given by the output voltage of the other half cycle of the exciter coil. 3. The ignition device for an internal combustion engine according to claim 1, wherein the signal voltage is provided by an output voltage of a signal coil provided separately from the exciter coil.