JPH0545824Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a capacitor discharge type ignition device for an internal combustion engine.

[Prior Art] A capacitor discharge type ignition device for an internal combustion engine includes an exciter coil provided in a magnet generator attached to the internal combustion engine, an ignition coil, and an exciter coil provided on the primary side of the ignition coil. an ignition energy storage capacitor that is charged by the positive half-cycle output of the ignition energy storage capacitor; a discharge control thyristor that is provided to discharge the charge in the capacitor to the primary coil of the ignition coil when conductive; and an ignition timing control circuit that controls the timing of applying an ignition signal to the thyristor according to the speed.

In an internal combustion engine, in order to prevent combustion, it is necessary to ignite at a delayed timing in a low speed range. Further, from the medium speed range to the high speed range, the ignition timing must be advanced in order to improve output and acceleration performance, and above a certain rotational speed in the high speed range, the ignition timing must be delayed to prevent overspeed. In this case, it is necessary to obtain ignition characteristics as shown in FIG.

In conventional capacitor discharge type ignition systems, the ignition timing control circuit includes a circuit for detecting the rotation speed, a circuit for determining the ignition timing in the low speed range, a circuit for obtaining advance angle characteristics in the medium to high speed range, and a circuit for determining the ignition timing in the high speed range. Separate circuits were provided for obtaining retardation characteristics at or above the set rotational speed.

[Problems that the invention aims to solve] In conventional ignition systems, the circuit that determines the ignition timing includes a rotation speed detection circuit, a circuit that determines the ignition timing in the low speed range, and a circuit that determines the ignition timing in the medium and high speed range. Because the circuit and the circuit that obtains retard characteristics above the set rotation speed in the high-speed range were provided separately,
It was inevitable that the circuit configuration would become complicated.

The purpose of this invention is to provide an internal combustion engine with ignition characteristics in the low speed range, advance characteristics in the medium and high speed range, and retardation characteristics above the set rotation speed in the high speed range with a simple circuit configuration. The purpose is to provide an ignition device.

[Means for Solving the Problems] The present invention includes an exciter coil provided in a magnet generator attached to an internal combustion engine, an ignition coil, and a positive side of the exciter coil provided on the primary side of the ignition coil. An ignition energy storage capacitor is charged by the output of a half cycle of
An ignition device for an internal combustion engine that includes a discharge control thyristor provided to cause discharge to a coil, and an ignition timing control circuit that controls ignition timing by controlling the timing of applying an ignition signal to the thyristor. It is.

In the present invention, the ignition timing control circuit has the following features:
an ignition signal supply circuit that supplies an ignition signal to the gate of the thyristor with the negative half-cycle output of the exciter coil; first and second transistor switches; a trigger control capacitor; and a transistor switch trigger circuit; Equipped with an ignition timing correction capacitor.

The first transistor switch is arranged to bypass the firing signal of the thyristor from the gate of the thyristor when conductive and from the exciter coil when the exciter coil produces a negative half-cycle output. A base current is applied and conducts.

The second transistor switch is configured to, when conductive, shunt the base current of the first transistor switch away from the first transistor switch to turn the first transistor switch off.

The trigger control capacitor is provided to be charged to one polarity with a constant time constant by the output voltage of the negative half cycle of the exciter coil, and the transistor switch trigger circuit is configured such that the terminal voltage of the trigger control capacitor is the set value. When the second
A base current is applied to the second transistor switch to make the second transistor switch conductive.

The ignition timing correction capacitor is installed in an ignition signal supply circuit that provides an ignition signal to the thyristor using the output of the negative half cycle of the exciter coil.
It is charged by the output of the positive half cycle of the exciter coil, and discharged between the gate and cathode of the discharge control thyristor when the exciter coil generates the output of the negative half cycle.

[Operation] In a region below the engine starting rotation speed, the charging voltage of the trigger control capacitor does not reach a level that triggers the second transistor switch, so the second transistor switch maintains a cut-off state. In this state, the first transistor switch is conductive for the entire period when the output of the negative half cycle of the exciter coil is above a predetermined threshold level and blocks the supply of the firing signal to the thyristor. cannot conduct.

When the rotational speed exceeds the starting rotational speed, the terminal voltage of the trigger control capacitor reaches a level that can trigger the second transistor switch at the peak position of the output of the negative half cycle of the exciter coil. This causes the second transistor switch to conduct, thereby turning off the first transistor switch and providing a firing signal to the thyristor. This causes the thyristor to conduct and discharge the charge in the ignition energy capacitor to the primary coil of the ignition coil. This discharge causes a large change in magnetic flux in the iron core of the ignition coil, which induces a high voltage in the secondary coil of the ignition coil.
A spark is generated in the spark plug connected to the next side, igniting the engine.

As the rotational speed of the engine increases, the output of the exciter coil increases, and the phase in which the terminal voltage of the trigger control capacitor reaches the trigger level of the second transistor advances, so the ignition timing advances.

Above a certain rotational speed, the second transistor switch becomes conductive during the entire negative half cycle of the exciter coil, and the first transistor switch remains cut off during the entire negative half cycle of the exciter coil. In this state, a firing signal is supplied to the thyristor when the output voltage of the exciter coil reaches a predetermined trigger level, so the advance angle characteristic is determined by the output waveform of the exciter coil, but the output of the exciter coil is Because of the reaction, the phase at which the output of the negative half cycle of the exciter coil reaches a level that can trigger the thyristor is delayed. However, at this time, since the discharge current of the ignition timing correction capacitor is superimposed on the ignition signal current supplied from the exciter coil to the thyristor, a delay in ignition timing is prevented.

As the rotational speed increases further, the charging voltage of the trigger control capacitor begins to decrease due to the armature reaction of the magnet generator. Therefore, the phase in which the terminal voltage of the trigger control capacitor reaches the trigger level of the second transistor switch is delayed, and the ignition timing is delayed.

Therefore, it is possible to obtain characteristics in which the ignition timing is delayed at low speeds, the ignition timing advances from the medium speed range to the high speed range, and the ignition timing is delayed above a certain rotational speed in the high speed range.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention, in which 1 is an ignition coil having a primary coil 1a and a secondary coil 1b, one end of which is grounded, and 2 is an ignition coil with one end of the primary coil 1a connected to the ground. The ignition energy storage capacitor 3 is connected to the ground terminal, and 3 is a discharge control thyristor connected between the other end of the capacitor 2 and the ground with its cathode facing the ground.

4 is an exciter coil installed in a magnet generator attached to an internal combustion engine, and one end of this exciter coil is connected to a capacitor 2 through a diode 5.
and the thyristor 3, and the other end is grounded through the resistor 6. The other end of the exciter coil 4 is also connected through resistors 7 and 8 to the anode of a diode 9, whose cathode is connected to the gate of the thyristor 3.
One end of an ignition timing correction capacitor 10 is also connected to the other end of the exciter coil 4, and the other end of the capacitor 10 is connected to a resistor 7 through a diode 11.
It is connected to 8 connection points. The connection point between capacitor 10 and diode 11 is connected to the anode of diode 9 through resistor 12, and resistors 7, 8, and 12, capacitor 10, and diode 11
and the diode 9, the exciter coil 4
An ignition signal supply circuit is configured to supply an ignition signal to the thyristor 3 at the output of a negative half cycle (a half cycle in which a voltage with a polarity opposite to the illustrated arrow is generated).

A capacitor 13 and a resistor 14 are connected in parallel between the gate and cathode of the thyristor 3, and the collector of an NPN transistor 15 constituting the first transistor switch is connected to the anode of the diode 9. The emitter of the transistor 15 is grounded, and the base is connected through a resistor 16 to an NPN transistor 17 constituting a second transistor switch.
connected to the collector. transistor 15
A diode 18 is connected between the base and ground with its anode facing the ground side. The collector of the transistor 17 is connected to the cathode of the diode 11 through the resistor 19, and the base is connected to the anode of the Zener diode 20. The cathode of the Zener diode 20 is connected through a resistor 22 to the other end of a trigger control capacitor 21 whose one end is grounded, and a resistor 23 is connected to both ends of the capacitor 21 . The cathode of a diode 25 is connected to the non-grounded terminal of the capacitor 21 through a resistor 24.
The anode of is connected to the connection point between the exciter coil 4 and the resistor 7. A diode 26 with its anode facing the ground is connected between one end of the exciter coil 4 and the ground. Also capacitor 10
A resistor 27 is connected between the connection point of the diode 11 and the ground.
is connected.

A spark plug 28 attached to a cylinder of an internal combustion engine (not shown) is connected to the secondary coil 1b of the ignition coil 1.

In this embodiment, the ignition signal supply circuit, transistors 15 and 17, and resistors 6, 16, 1
9, 23, 24, 27 and diodes 18, 25
The capacitor 21 and the Zener diode 20 constitute an ignition timing control circuit.

In this control circuit, the trigger control capacitor 21 is charged to the illustrated polarity at a constant time constant by the output voltage of the negative half cycle of the exciter coil through the diode 25 and the resistor 24.

Further, the resistor 22 and the Zener diode 20 provide a transistor switch trigger that applies a base current to the transistor 17 (second transistor switch) to make the transistor 17 conductive when the terminal voltage of the trigger control capacitor 21 exceeds a set value. The circuit is configured.

Figure 2B shows the terminal voltage of the capacitor 21 at a speed N1 near the starting rotation speed, a speed N2 in the advance region, and a speed N3 exceeding the set rotation speed in the high speed region.
The change in Vc is shown against the rotation angle θ.
When the terminal voltage of this capacitor 21 exceeds the Zener voltage Vz of the Zener diode 20, the transistor 17 is turned on and the transistor 15 is turned off. This allows the ignition signal to be applied to the thyristor 3, and the ignition operation is performed.

Figure 2C shows the waveform of the gate-cathode voltage VGK of the thyristor 3 when the rotational speeds are N1, N2, and N3 with respect to the rotation angle θ, and θ1, θ
2 and θ3 indicate the ignition timing (angle) when the rotational speeds are N1, N2, and N3, respectively.

To explain the operation of the above embodiment in detail, the exciter coil 4 is arranged in a three-pole magnet generator,
A voltage waveform as shown in FIG. 2A is induced in synchronization with the rotation of the internal combustion engine. When the exciter coil 4 generates a positive half-cycle output voltage in the direction of the arrow in FIG.
The ignition energy storage capacitor 2 is charged to the polarity shown in the figure along the route of the capacitor 2 → primary coil 1a → resistor 6 → exciter coil 4. Also, in the positive half cycle of this exciter coil, exciter coil 4 → capacitor 2 → primary coil 1a
The ignition timing correction capacitor 10 is charged to the polarity shown in the figure along the path of →resistor 27→capacitor 10→exciter coil 4.

If the transistor 15 is in the cut-off state when the exciter coil generates a negative half-cycle output, the path from the exciter coil 4 to the resistors 7 and 8 to the diode 9 to the gate and cathode of the thyristor 3 to the diode 26 to the exciter coil 4 And, exciter coil 4 → capacitor 10 → diode 11
→ Resistor 8 → Diode 9 → Between gate and cathode of thyristor 3 → Diode 26 → Exciter coil 4 path and Exciter coil 4 → Capacitor 1
An ignition signal is supplied to the thyristor 3 through a path of 0 → resistor 12 → resistor 8 → diode 9 → gate and cathode of thyristor 3 → diode 26 → exciter coil 4.

During the negative half cycle of the exciter coil, trigger control capacitor 21 is also charged through diode 25 and resistor 24 to the polarity shown. In the region below the starting rotation speed, the output voltage of the exciter coil is low and the terminal voltage of the trigger control capacitor 21 does not reach a level that makes the Zener diode 20 conductive.
is not conductive. Therefore, a base current is applied to transistor 15 through resistors 19 and 16, making transistor 15 conductive. transistor 15
When conducts, the ignition signal to be applied to the gate of the thyristor 3 through the diode 9 is bypassed from the thyristor 3 through the collector-emitter of the transistor 15. Thyristor 3 is therefore not given a firing signal and is not conducting.

When the rotational speed exceeds the starting rotational speed, the terminal voltage of the trigger control capacitor 21 reaches a level that makes the Zener diode 20 conductive at the peak position of the output of the exciter coil 4 in the negative half cycle. As a result, the transistor 17 becomes conductive, so that the transistor 15 is cut off, and an ignition signal is given to the thyristor 3. This makes the thyristor 3 conductive and ignites the energy capacitor 2.
is discharged to the primary coil 1a of the ignition coil. This discharge causes a large magnetic flux change in the iron core of the ignition coil, so the secondary coil of the ignition coil
A high voltage is induced in 1b, and a spark is generated in the spark plug 28.

As the rotational speed of the engine increases, the output of the negative half cycle of the exciter coil 4 increases, and the phase in which the terminal voltage of the trigger control capacitor 21 reaches the trigger level of the transistor 17 advances, so the ignition timing advances. go.

When the rotational speed of the engine further increases and reaches a certain rotational speed, the transistor 17 becomes conductive for the entire negative half cycle of the exciter coil 4, and the transistor 15 remains cut off for the entire negative half cycle of the exciter coil. I come to do it. In this state, a firing signal is supplied to the thyristor 3 when the output voltage of the exciter coil reaches a predetermined trigger level, so that the advance angle characteristic is determined by the output waveform of the exciter coil. Since the output of the exciter coil decreases due to the armature reaction, the phase in which the output of the negative half cycle of the exciter coil reaches a level capable of triggering the thyristor is delayed. However, at this time, the discharge current of the ignition timing correction capacitor 10 charged by the output of the positive half cycle of the exciter coil is superimposed on the ignition signal current supplied from the exciter coil to the thyristor, so the ignition timing is delayed. Prevented.

When the rotational speed further increases, the charging voltage of the trigger control capacitor begins to decrease due to the armature reaction of the magnet generator, as indicated by N3 in FIG. 2B. In this situation, trigger control capacitor 2
The phase in which the terminal voltage of the transistor 1 reaches the Zener voltage of the Zener diode 20 is delayed, and the phase in which the transistor 17 is turned on and the transistor 15 is turned off is delayed, so that the ignition timing is delayed.

Therefore, as shown in FIG. 3, a characteristic can be obtained in which the ignition timing is delayed at low speeds, the ignition timing advances from the medium speed range to the high speed range, and the ignition timing is delayed above a certain rotational speed in the high speed range.

In the above embodiment, the slope of the advance angle and retard angle characteristics can be adjusted as appropriate by changing the charging and discharging characteristics of the capacitor 21.

[Effects of the Invention] As described above, according to the present invention, the terminal voltage of the trigger control capacitor is changed by utilizing the change in output of the exciter coil accompanying changes in the rotational speed of the internal combustion engine, and the change in terminal voltage of this capacitor is used to control the first and second transistor switches, thereby controlling the timing of supplying an firing signal to the thyristor, thereby obtaining advance and retard characteristics. Therefore, there is no need to provide a rotational speed detection circuit, an advance circuit, and a retard circuit separately, and this has the advantage of simplifying the circuit configuration.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a waveform diagram showing voltage waveforms at various parts of Fig. 1, and Fig. 3 is a diagram showing ignition characteristics obtained by the embodiment of the present invention. It is. 1... Ignition coil, 2... Capacitor for ignition energy storage, 3... Thyristor for discharge control, 4
...Exciter coil, 5, 9, 11, 18, 2
6...Diode, 10...Ignition timing correction capacitor, 21...Trigger control capacitor, 6,
7, 8, 14...Resistor, 15...Transistor (first transistor switch), 17...Transistor (second transistor switch).

Claims (1)

[Claims for Utility Model Registration] An exciter coil provided in a magnet generator attached to an internal combustion engine, an ignition coil, and a positive half-cycle output of the exciter coil provided on the primary side of the ignition coil. an ignition energy storage capacitor charged by the ignition energy storage capacitor; a discharge control thyristor provided to discharge the charge of the capacitor to the primary coil of the ignition coil when conductive; and an ignition timing control circuit for controlling ignition timing, wherein the ignition timing control circuit sends an ignition signal to the gate of the thyristor using the output of the negative half cycle of the exciter coil. a firing signal supply circuit for supplying a firing signal; and when the exciter coil generates a negative half-cycle output, a base current is applied from the exciter coil to conduct, thereby bypassing the firing signal from the gate of the thyristor. a first transistor switch; a second transistor switch provided to cut off the first transistor switch when conductive; and a time constant determined by the output voltage of the negative half cycle of the exciter coil; a trigger control capacitor that is charged to one polarity in the trigger control capacitor; and when the terminal voltage of the trigger control capacitor exceeds a set value, a base current is applied to the second transistor switch to make the second transistor switch conductive. a transistor switch trigger circuit disposed in the ignition signal supply circuit to be charged by the positive half-cycle output of the exciter coil, and to cause the discharge to occur when the exciter coil generates a negative half-cycle output; An ignition device for an internal combustion engine, comprising: an ignition timing correction capacitor that discharges electricity between the gate cathode of a control thyristor.