JPS5979072A - Ignition device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the overrunning of the engine promptly by a method wherein a thyristor for delaying spart angle is provided in parallel to the trigger signal input terminal of the thyristor for ignition and the thyristor for delaying spark angle is conducted when the generating voltage of an exciter coil is larger than a predetermined value. CONSTITUTION:The thyristor 18 for delaying spark angle is provided in parallel to the input terminal of the trigger signal of the thyristor 5 for ignition. The capacitor 25 is charged by the generating voltage of the exciter coil 9 and when the voltage of the capacitor 25 has arrived at a voltage determined by a Zener diode 26, a transistor 22 is put ON and the thyristor 18 for delaying spark angle is conducted. A current, flows through the gate of the thyristor 5, is reduced by the current determined by a resistor 17, therefore, the ignition timing is delayed. According to this method, the ignition timing upon the overrunning may be delayed without delay of response.

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 υ, 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. was there. 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 become wet with unburned gas, making it difficult to ignite or causing a backfire. There were drawbacks. Therefore, a device has been proposed that suppresses the increase in engine speed by delaying the ignition position when the engine speed reaches a set value.
Conventional devices of this kind use a Pong-Alug circuit to detect the rotation speed, which has a large response delay, and has the disadvantage that accurate over-speed prevention operation cannot be performed when the rotation speed suddenly increases or decreases. □The 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 the overspeed prevention operation, and reduces response delay. Our goal is to provide the following.

The present invention includes an ignition circuit that generates a high voltage for p-ignition by operating a primary current control semiconductor switch that controls the primary current of an ignition coil, and an ignition circuit that induces an alternating current voltage in synchronization with the rotation of the internal combustion engine. and an exciter coil connected to the ignition circuit so as to give ignition energy to the ignition circuit with the output of one half cycle, and a signal voltage generated in synchronization with the rotation of the internal combustion engine reach a first threshold value. an ignition timing signal supply circuit that supplies an ignition timing signal to a trigger signal input terminal of the primary current control semiconductor switch to perform an ignition operation; In an ignition device for an internal combustion engine comprising an ignition position control circuit that controls the operating position of a semiconductor switch for primary current control to be delayed, the semiconductor switch for primary current control is arranged in parallel between the signal input terminals. a series circuit of a current limiting element and a retarding thyristor connected together, and providing an ignition signal to the dart of the retarding thyristor when the signal voltage reaches a second threshold lower than the first threshold; an ignition signal supply circuit, a capacitor for determining the set rotation speed that is charged at a constant time constant by the signal voltage, and a third circuit whose terminal voltage of the capacitor for determining the set rotation speed is lower than the second threshold value. The ignition signal is allowed to be given to the retard thyristor when the ignition signal is less than the third threshold; The ignition position control circuit is characterized by comprising a retarding thyristor control circuit which prevents an ignition signal from being applied to the thyristor.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, in which an ignition coil 2 having a 1 μm primary coil 1a and a secondary coil 1b is attached to a cylinder of an engine (not shown).
This is an ignition bladder connected to both ends of the secondary 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 semiconductor switch for primary current control whose cathode is connected to the anode of the diode 3 and to the anode of the thyristor 5, and a resistor 6 is connected in parallel between the thyristor 5 and the cathode. There is. A diode 7 is connected in parallel to both ends of the primary coil 1a with the cathode facing the ground side, and a capacitor discharge type ignition circuit 8 is constituted by the above-mentioned 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 the entire diode 1o. Therefore, the output voltage of the exciter coil 9 in one half cycle in the direction of the solid arrow shown in the figure (hereinafter referred to as positive direction voltage) υ. As a result, capacitor 4 is charged through diode 10 to the polarity shown. In order to obtain a signal voltage for controlling the thyristor 5 from the output voltage (hereinafter referred to as negative direction voltage) ν0' 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 connected. One end of a resistor 13 is connected to the cathode of this diode. The other end of the resistor 13 is connected to the anode of the diode 14.
The cathode of is connected to the non-ground terminal of the exciter coil 9. The connection point between the resistor 13 and the anode of the diode-PI3 is connected to the cathode of the thyristor 5.
The connection point between the diode 110 and the cathode is connected to the cathode of a first Zener diode 15 whose anode is connected to the dart of the thyristor 5.

The above diode 11. Resistance 13. An ignition timing signal is supplied by the diode 14 and the first Zener diode 15 to give an ignition timing signal to the dart (trigger signal input terminal) of the SIRISK (semiconductor switch for primary current control) 5 by the negative voltage of the exciter coil 9. The circuit is configured. That is, when a negative voltage is induced in the exciter coil 9, the exciter coil 9 → diode 11
A current flows through the path of →resistance 13→diode 14→exciter coil 9, and a signal voltage v1 appears across the resistor 13. When this signal voltage v1 reaches a first threshold value corresponding to the Zener voltage z1 of the Zener diode 15, an ignition timing signal is applied to the dart of the thyristor 5 through the Zener diode 15, and the 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 multi-ignition coil, and a high voltage for ignition is induced in the secondary coil 1b. This high voltage is applied to the ignition glove 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 retarding thyristor 18, and this series circuit is connected to a thyristor (semiconductor switch for primary current control) 5 through a Zener diode 15.
The dart is connected in parallel between the cathodes (between the signal input terminals). The cathode of the thyristor 180 is grounded through the diode 3, and a resistor 19 is connected in parallel between the gate and cathode of this thyristor. A second Zener diode 2 is connected to ff-) of the thyristor 18.
0 is connected, and the cathode of the Zener diode 20 is connected to the non-grounded terminal of the resistor 13 through the resistor 21. The Zener voltage v2□ of the Zener diode 20 is set lower than the Zener voltage V of the first Zener diode 15, and the signal voltage obtained across the resistor 13 by the resistor 21 and the Zener diode 20 is equal to the first An ignition signal supply circuit is configured to provide an ignition signal to the thyristor 18 when a second threshold value (Zener voltage v72) lower than the threshold value of is reached.

The collector of a transistor 22 whose trench emitter is grounded through the diode 3 is connected to the gate of the thyristor 18, and a resistor 23 is connected in parallel between the gate emitters of the transistor 22. 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 130.
3 by the signal voltage v1 obtained across 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 pace of the transistor 22. Zener voltage v2 of the third Zener diode 26. is set lower than the Zener voltage v2□ of the second Zener diode 20,
This third Zener diode 26, resistor 23, and transistor 22 connect 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 retarding timing risk 18, and the terminal of the set rotation speed determining capacitor 25 A retard thyristor 18 is configured with a retard thyristor control circuit that prevents a firing signal from being applied to the retard thyristor 18 when the voltage exceeds a third threshold. 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 110.
When conductive, the charge in the capacitor 25 is rapidly discharged through the variable resistor 24, diode 27, and thyristor 5.Next, the operation of the above ignition device will be explained with reference to FIGS. 2 and 3. do. When a positive voltage v6 is generated in the exciter coil 9, the capacitor 4 is charged along the paths of the exciter coil 9 → diode 10 → capacitor 4 → diode 7 and the primary coil 1a → exciter coil 9. Next, a negative direction voltage υ is applied to the exciter coil 9. When ' occurs, a current flows along the path of exciter coil 9 → diode 11 → resistor 13 → diode 14 → exciter coil 9, and a signal voltage v1 appears across the resistor 130. This signal voltage v
1 is applied to the capacitor 25 through the variable resistor 24, so the capacitor 25 is charged to the illustrated polarity with a constant time constant. When the engine speed N is not equal to the set value NIl, the engine rotation angle θ is as shown in FIG. After the signal voltage v1 and the terminal voltage v2 of the capacitor 25 rise at the angle θ1, the terminal voltage v2 of the capacitor 25 rises to the third level.
The Zener voltage v2 of the Zener diode 26 of Then, at an angle θl, the signal voltage v1 reaches the Zener voltage v21 of the first Zener diode 15. When the voltage V2 reaches the Zener voltage v73 at the angle θ1, a pace current flows through the transistor 22.
becomes conductive and prevents the ignition signal from entering r-1 of the thyristor 18. At angle θ1, signal voltage V1 becomes Zener voltage v2. When the ignition timing signal reaches the thyristor 5, the 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. As the rotational speed of the engine increases, the peak value of the signal voltage v1 increases and its rise becomes faster, so that the signal voltage v1 becomes higher than the Zener voltage v7. The angle at which it reaches progresses, and the ignition position advances.

When the rotational speed N of the engine exceeds the set value N1, as shown in FIG.
Since the signal voltage v1 reaches the Zener voltage V2 of the second Zener diode 20, a firing signal is input to the thyristor 18, and the thyristor 18 becomes conductive. When the SIRISK 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 v1 eventually reaches the Zener diode 1 at an angle θl'.
The Zener voltage V of 5 is reached, and the ignition operation is performed at this angle θi'. As mentioned above, since the signal 'fJLFEV1 decreases at the angle θa due to the conduction of the thyristor 18,
The angle (ignition position) θl' at which the signal voltage v1 reaches the Zener voltage V is an angle of 0. When the thyristor 18 is not conductive at L, the signal voltage v1 becomes the Zener voltage v2.
Therefore, the characteristic of the ignition position with respect to the rotational speed N is such that the ignition position is retarded in a stepwise manner at the set rotational speed Ns, as shown in Fig. 4. By retarding the ignition position, the increase in engine speed is suppressed and the engine speed is lowered below the set value.

In FIG. 4, TDC indicates the top dead center of the engine.

In the device of the present invention, by changing the resistance value of the current limiting element connected in series to the retarding thyristor 18,
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. In the above embodiment, the resistance value R of the variable resistor 17 is
By decreasing 17, the retard angle 'Ik can be increased, and by decreasing the resistance value R24 of the variable resistor 24, the set value N,4'i of the rotation speed can be changed to a higher value. be able to. 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 resistor 24, the diode 27, and the thyristor 5 when the thyristor 5 is turned on, so that the capacitor 25 is repeatedly charged and discharged under the same conditions every cycle. 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 canceled. Furthermore, since a pump-up circuit for detecting the rotational speed is not used, the 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 is charged by the output of a coil that generates voltage in synchronization with the rotation of the engine. , a large-capacity second capacitor charged by the charge of this 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. On the other hand, in the present invention, since it is sufficient to provide one capacitor 25 of small capacity for determining the set rotation speed, the circuit can be simplified, and the device can be made smaller and the price can be reduced. I can do it.

t.

Next, FIG. 5 shows a second embodiment of the present invention.
The difference from the embodiment shown in FIG. 1 is that a second Zener diode 20' (il-) is inserted between the collector of the Lanzo star 22 and the dart of the thyristor 18. 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 dirt cathodes of the thyristor 5, and one end of a capacitor 3o is connected to the dirt of the thyristor 5 through the resistor 29. The other end of the capacitor 3o 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 the first Zener diode 15 are connected to the dart and anode of the thyristor 31, respectively, and the anode and cathode of the diode 14 are connected to the cathode of the thyristor 31 and the non-grounded terminal of the exciter coil 9, respectively. Diode 28, resistor 29, capacitor 30. Thyristor 3
1, a resistor 32, a Zener diode 15, and a diode 14 constitute an ignition timing signal supply circuit that provides an ignition timing signal to the thyristor 5. resistance 1
3 is connected in parallel to both ends of the thyristor 31, and this resistor 1
A signal voltage v1 appears at both ends of 3.

The ignition position control circuit 16 is configured in the same manner as the example shown in FIG. 17 are all connected to the anode (ground) of the thyristor 31.

In the embodiment shown in FIG.
negative direction voltage υ. ' occurs, current flows through the path of exciter coil 9 → diode 28 → resistor 29 → capacitor 30 → diode 14 → exciter coil 9 and the path of exciter coil 9 → resistor 13 → diode 14 → exciter coil 9, and is charged to the polarity shown. As the capacitor 30 is charged, the signal voltage 13 obtained across the resistor 13 increases, and when this signal voltage v1 reaches the first threshold, the Zener diode 15 becomes conductive and an ignition signal is sent to the thyristor 31. enter. As a result, the thyristor 31 becomes conductive, and the charge in the capacitor 3o is discharged through the resistor 29, between the gate and cathode of the thyristor 5, and through the thyristor 31. This discharge current gives an ignition timing signal to the thyristor 5,
An ignition operation is performed. The signal voltage v1 appearing across the resistor 13 is also applied across the variable resistor 24 to the capacitor 25.
, the capacitor 25 is charged with a constant time constant. If the engine speed is less than the set value,
Before the signal voltage v1 reaches a level that makes the Zener diode 15 conductive, the terminal voltage of the capacitor 25 reaches the Zener voltage of the Zener diode 26, and the transistor 2
Since the thyristor 2 is made conductive, the thyristor 18 is not made conductive, and no over-rotation prevention operation is performed. When the rotation speed exceeds the set value, the signal voltage v1 becomes equal to or higher than the Zener voltage of the Zener diode 20 before the terminal voltage v2 of the capacitor 25 reaches the Zener voltage of the Zener diode 26, so the thyristor 18 becomes conductive and over-rotation prevention operation is performed. will be carried out.

FIG. 7 shows a fourth embodiment of the present invention, in which a signal coil 35 is provided separately from the exciter coil 9, and the output of this signal coil 35 is connected to a diode 36.
It is stamped on both ends of the resistor 13 through the t-. 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 90. For example, by interrupting the current flowing from the exciter coil through the semiconductor switch for primary current control at the ignition position, a high voltage is induced in the exciter coil, and this high voltage is further boosted by the ignition coil for ignition. The present invention can also be applied when a current interrupter type ignition circuit is used to obtain a high voltage of .

As described above, according to the present invention, there is no need to provide a rotation speed detection circuit using a pump-up circuit, so response delay can be reduced, and even when the rotation speed suddenly increases or decreases, accurate Over-rotation prevention operation can be carried out, and hysteresis does not occur in the over-rotation prevention operation. Furthermore, since no unburned gas is emitted,
Prevents the ignition glove from getting wet and causing a packfire.

[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 present invention in detail, and FIG. 4 1 is a diagram showing an example of the characteristics of the ignition position with respect to the rotational speed obtained according to the present invention. DESCRIPTION OF SYMBOLS 1... Ignition coil, 2... Spark plug, 4... Capacitor, 5... Thyristor (semiconductor switch for primary current control), 9... Exciter coil, 11... Diode, 13... ...Resistance, 14...Diode, 1
5... Zener diode, 16... Ignition position control circuit, 17... Variable resistor (current limiting means), Engineering 8.
... Retard angle sirisk, 20... Zener diode, 22... Transistor, 24... Variable resistor, 2
5... Capacitor for determining the set rotation speed, 26... Zener diode.

Claims (3)

[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 the ignition coil, and an ignition circuit that induces an alternating current voltage in synchronization with the rotation of the internal combustion engine. When an exciter coil connected to the ignition circuit so as to give ignition energy to the ignition circuit with the output of one half cycle and a signal voltage generated in synchronization with the rotation of the internal combustion engine reach a first threshold value. an ignition timing signal supply circuit that applies an ignition timing signal to a trigger signal input terminal of the primary current control semiconductor switch to perform an ignition operation; In an ignition device for an internal combustion engine, the ignition position control circuit includes: an ignition position control circuit that controls the operating position of a current control semiconductor switch to be delayed;
a series circuit of a current limiting element and a retarding thyrisk connected in parallel between the trigger signal input terminals of the semiconductor switch for primary current control; and a second circuit in which the signal voltage is lower than the first threshold. an ignition signal supply circuit that provides an ignition signal to the dart of the retard thyristor when the threshold value of the thyristor is reached; allowing 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; and the capacitor for determining the revised rotation speed; An internal combustion engine, comprising: a retard thyristor control circuit that prevents an ignition signal from being applied to the retard thyristor when a terminal voltage of the retard thyristor is equal to or higher than the third threshold; ignition device. (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.