JPH04175466A - Capacitor discharge type ignition system for internal combustion engine - Google Patents

Abstract

PURPOSE:To simplify the structure of an ignition system by superposing the output current of a battery to the short-circuit current of an exciter coil so as to obtain a voltage sufficiently high in a low speed operation even though the number of turns of the exciter coil is reduced. CONSTITUTION:When the ignition device is applied to a two-cycle internal combustion engine, a control circuit 3 to control the current feeding to the thyristors S1 and S2 of ignition main circuits 1 and 2 of the cylinders is provided, and the output signals of the first and the second pulser coils 4 and 5 for cylinders are given to the control circuit 3. And an exciter coil 10 is provided in a magnet generator, and its one end is connected to a battery 11 through a transistor T1 and a key switch SW. Furthermore, in parallel to a DC circuit of the exciter coil 10 and the battery 11, a booster circuit 16 which consists of a switch 14 for short circuit to continue when the exciter coil 10 generates one side half cycle of output voltage of the polarity applied to the battery voltage, and a cutoff circuit 15 to make the switch 14 in a cutoff condition when the current reaches a specific value, is provided.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a capacitor discharge type ignition device for an internal combustion engine that operates using an exciter coil provided in a magnet generator driven by the internal combustion engine as a power source. be.

[Prior Art] In a capacitor discharge type internal combustion engine ignition system that charges a capacitor with a voltage induced in an exciter coil as the magnet generator rotates, the capacitor is sufficiently charged from low to high speeds of the engine. In order to charge at a high voltage and perform a satisfactory ignition operation, the number of turns was extremely large (3[
IH~7θ@O turn) Exciter coil for low speed,
It is necessary to provide a high-speed exciter coil with a relatively small number of turns, which poses the problem of complicating the structure of the generator.

Furthermore, since the exciter coil for low speeds needs to be wound with a large number of turns using a thin wire, there is a problem in that the workability of the winding is poor and troubles such as wire breakage are likely to occur.

Therefore, by using only one exciter coil wound with relatively thick wire and connecting a current cut-off type booster circuit to the exciter coil, a sufficiently high voltage is applied to the exciter coil from low to high speeds of the engine. An ignition device (Japanese Unexamined Patent Publication No. 172463/1983) was proposed that induces

A current cutoff type booster circuit includes a short-circuit switch that short-circuits an exciter coil, and a cutoff circuit that turns the short-circuit switch into a cut-off state when the short-circuit current of the exciter coil reaches a predetermined value. This interrupts the short-circuit current flowing through the exciter coil and induces a high voltage in the exciter coil.

[Problems to be Solved by the Invention] However, even in the previously proposed ignition system equipped with a current interrupt type booster circuit, in order to perform a satisfactory ignition operation near the starting rotation speed, the number of turns of the exciter coil must be greater than IHO turns. Because it is necessary to set the value to In addition, when winding the exciter coil with thick wire, 1000
Since it is difficult to wind an exciter coil with more than one turn around one pole of the stator, the exciter coil occupies two or more poles of the stator, and the pole around which other generator coils are wound is difficult. The problem was that there were fewer

Furthermore, as seen in Japanese Patent Application Laid-Open No. 61-132084,
A battery-operated capacitor that generates a high voltage for charging the capacitor by passing the primary current through the transformer using the battery voltage and intermittent the primary current of the transformer using a switch that is controlled on and off by the output of the oscillation circuit. Discharge type ignition devices are well known, but this type of ignition device requires an oscillation circuit outside the transformer, which poses a problem in that the configuration of the ignition device becomes complicated.

An object of the present invention is to provide a capacitor discharge type internal combustion engine ignition device equipped with a current cutoff type booster circuit that boosts the output voltage of an exciter coil, in which the number of turns of the exciter coil is further reduced than in the conventional type, and the voltage boosting voltage is increased. The purpose is to improve the efficiency of the circuit.

[Means for Solving the Problems] The present invention makes it possible to obtain a sufficiently high voltage at low speeds even if the number of turns of the exciter coil is reduced by superimposing the output current of the battery on the short-circuit current of the exciter coil. This is what I did.

Therefore, the ignition device of the present invention includes an exciter coil provided in a magnet generator, a battery connected in series to the exciter coil, and an exciter coil connected in parallel to the series circuit of the exciter coil and the battery. a short-circuiting switch that becomes conductive when the output voltage of one half cycle of polarity is added to the battery voltage; and when the current flowing through the short-circuiting switch reaches a predetermined value, the shorting switch is turned off. A current interrupting type step-up circuit having a interrupting circuit that causes configured.

A battery input switch can be inserted between the exciter coil and the battery. In this case, a trigger circuit is provided that turns on the battery input switch when, for example, the exciter coil generates an output voltage of one half cycle.

When a battery charging switch is provided as described above, a turn-off circuit is provided that shuts off the battery charging switch when the internal combustion engine's rotational speed exceeds a set value. The battery can be disconnected. In this case, connect a diode in parallel with the series circuit between the battery input switch and the battery so that the battery voltage is applied in the opposite direction, so that the short-circuit current of the exciter coil can be maintained even when the battery is disconnected. Let it flow.

Further, in the case where a battery input switch is provided between the exciter coil and the battery, a trigger signal may be given to the battery input switch using the voltage of the battery. In this case, a switch control circuit is provided that turns off the battery input switch when the discharge thyristor is conductive.

Also in this case, in order to allow a short-circuit current to flow through the exciter coil when the battery input switch is cut off, the battery voltage is connected in parallel to the series circuit between the battery input switch and the battery. Connect a diode that applies voltage in the opposite direction.

Furthermore, in this case, a turn-off circuit can be provided to turn off the battery charging switch when the rotational speed of the internal combustion engine exceeds a set value.

[Function] As mentioned above, if the battery output current is superimposed on the short-circuit current of the exciter coil, the output voltage of the exciter coil will be low when the engine is running at low speed (although the current cutoff value can be increased). , a sufficiently high voltage can be induced in the exciter coil.Therefore, the number of turns in the exciter coil can be reduced.According to experiments, sufficient ignition performance can be obtained at low speeds even when the number of turns in the exciter coil is 500 turns or less. I was able to do that.

Furthermore, if a battery input switch is provided between the exciter coil and the battery, and the switch is cut off when the engine rotation speed exceeds a set value, Since the battery can be disconnected, unnecessary consumption of the battery can be prevented. In addition, since the number of turns of the exciter coil is small, it is possible to prevent the short circuit current of the exciter coil from becoming excessive in a region exceeding the set rotational speed, and it is possible to reduce heat generation.

Furthermore, by flowing the primary current through the transformer using the battery voltage,
Unlike a battery-operated capacitor discharge type ignition device that generates a voltage for charging the capacitor by cutting off the primary current, it does not require a transformer or an oscillation circuit, so the configuration of the ignition device can be simplified. .

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention applied to a two-cylinder internal combustion engine, in which G1 and IG2 are ignition coils for the first cylinder and the second cylinder, respectively;
Pl and Pl are spark plugs attached to the first cylinder and the second cylinder of the internal combustion engine. C1 and C2 are ignition energy storage capacitors for the first cylinder and second cylinder provided on the primary side of the ignition coils IGl and IG2, respectively.Sl and S2 are capacitors C1 and C2 when conductive, respectively. Ignition coil IGI and IG2 1
This is a thyristor that discharges electricity to the next coil.

Also, Di and D2 are diodes that supply charging current to capacitors C1 and C2, respectively, D3 and D4 are diodes connected in parallel to the primary coils of ignition coils IGl and IG2, respectively, and R1 and R2 are thyristors S1 and S2. ignition main circuit 1 for the first cylinder and the resistor connected between the gate cathode of the
An ignition main circuit 2 for the cylinders is configured.

3 is a control circuit for controlling the ignition position of the engine, and this control circuit is based on signals given from a first cylinder pulsar coil 4 and a second cylinder pulsar coil 5 provided in a signal generator attached to the engine. Trigger signals Vgl and Vg2 are applied to the gates of thyristors Sl and S2, respectively, at the ignition positions of the first cylinder and the second cylinder, which are calculated based on the calculation result.

The control circuit 3 also detects the rotational speed of the engine from the output of the pulsar coil, and when the rotational speed of the engine exceeds a set value or when the engine is stopped, it triggers a turn-off circuit to be described later. A turn-off command signal V+o to be used is generated.

The exciter coil 10 is provided in a magnet generator attached to the engine, and one end of the exciter coil is commonly connected to the anodes of diodes DI and D2. The other end of the exciter coil 10 is connected to the positive terminal of the battery 11 through the diode D5, the collector-emitter circuit of the transistor TI, and the key switch SW.
The negative terminal of battery 11 is grounded. A battery input switch 12 is constituted by a diode D5 and a transistor T1, and a diode D6 is connected in parallel to the series circuit of this switch 12 and the battery 11 in such a direction that the voltage of the batch IJ11 is applied in the opposite direction. ing. Further, a diode D7 with its anode facing the ground side is connected between one end of the exciter coil 10 and the ground.

The base of the transistor T1 is connected to the collector of a transistor T2 whose emitter is grounded via a resistor R3, and a resistor R4 is connected between the base and emitter of the transistor T2.
is connected. The base of transistor T2 is also connected to the positive terminal of battery 11 through resistor R5, and transistor T2 and resistors R3 to R5 connect battery 11 to the positive terminal.
A trigger circuit 13 is configured to provide a trigger signal to the battery input switch 12 with an output of 1.

The voltage of the battery 11 is also applied to the power supply terminal B of the control circuit 3.

A transistor T3 is also connected to one end of the exciter coil 10.
The collector of the transistor T3 is connected to the transistor T3, and the emitter of the transistor T3 is grounded through a resistor R6 having a sufficiently high resistance value.

A resistor R7 is connected between the base and collector of the transistor T3, and the transistor T3 and the resistors R6 and R7 constitute a short-circuiting switch 14 that short-circuits the exciter coil 10 and the battery 11.

A thyristor S3 is connected between the base of the transistor T3 and ground. A series circuit of resistors R8 and R9 is connected between the emitter of transistor T3 and ground, and the gate of thyristor S3 is connected to the connection point of these resistors. The thyristor S3 and the resistors R8 and R9 constitute a cutoff circuit 15 that turns off the short-circuit switch 14 when the short-circuit current of the exciter coil flowing through the short-circuit switch 14 reaches a predetermined value.

The short circuit switch 14 and the cutoff circuit 15 constitute a current cutoff type booster circuit 16.

A collector of a transistor T4 whose emitter is grounded is connected to the base of the transistor T2, and a resistor RIG is connected between the base of the transistor T4 and ground. A turn-off command signal Vjo, which is given from the control circuit 3 when the rotational speed of the engine exceeds a set value, is supplied to the base of the transistor T4 through the resistor R11. The transistor T4 and the resistors RIO and R11 constitute a turn-off circuit 17 that turns off the battery input switch 12 when the rotational speed of the engine exceeds a set value.

This embodiment also includes comparators CMI and CM2 and resistor R1.
A switch control circuit 18 is constituted by R2 to R15.

The output terminals of comparators CMf and CM2 are connected to transistor T2.
The inverting input terminals of both comparators are connected to the gates of thyristors S1 and S2 through resistors R12 and R13, respectively. A voltage dividing circuit consisting of a series circuit of resistors R14 and RI5 is connected to both ends of the battery 11, and the voltage dividing point of the voltage dividing circuit is connected to the comparators CMI and 0M.
It is commonly connected to the two non-inverting input terminals.

Next, the operation of the above embodiment will be explained. When the key switch SW is turned on, the control circuit 3 starts operating. Control circuit 3
outputs the turn-off command signal Vto when the engine is stopped, so the transistor T4 becomes conductive and the transistor T2 is turned off. At this time, transistor Tl is maintained in a cut-off state, and battery 11 is disconnected from exciter coil 10. Therefore, even if the key switch SW is held in the ON state when the engine is stopped, the battery 11
No current flows from the exciter coil 10 through the exciter coil 10, and wasteful consumption of the battery is prevented.

When the engine is rotated, the control circuit 3 stops outputting the turn-off command signal V+o, so the transistor T4 is cut off, allowing base current to be supplied to the transistor T2. Therefore, from battery 11 to transistor T
A base current is applied to the transistor T2, making the transistor T2 conductive, and a base current is applied to the transistor Tl, making the transistor TI conductive. Furthermore, when the engine is rotated, an alternating current voltage is induced in the exciter coil 10. When a positive half-cycle voltage is induced in the exciter coil 10 in the direction of the arrow shown in the figure, a current flows through the path of battery 11 → diode D5 → exciter coil 10 → resistor R7 → between the pace emitter of transistor T3 → resistor ゛6 → battery 11. flows, and transistor T3 becomes conductive. As a result, the exciter coil 10 and the battery 11 are substantially short-circuited through the transistor T3 and the resistor R6 whose resistance value is sufficiently small (through the short-circuit switch).

When this short circuit current reaches the set value and the voltage across the resistor R6 reaches the set value, a trigger signal is applied to the thyristor S3, causing the thyristor S3 to conduct.

As a result, the transistor T3 enters the cut-off state, and the short-circuit current flowing through the exciter coil 10 is cut off. When the engine starts, the output voltage of the exciter coil 10 is low, but in this embodiment, the output current of the battery 11 is superimposed on the short circuit current of the exciter coil, so the current cutoff value can be set sufficiently high. , exciter coil 1
A high voltage can be induced at zero.

Since the induced voltage of this exciter coil is applied to capacitors CI- and C2 via diodes D1 and D2, both capacitors are charged to the polarity shown. When a trigger signal is applied from the control circuit 3 to the thyristor S1 at the ignition position of the first cylinder, the thyristor S1 becomes conductive and discharges the charge in the capacitor CI to the primary coil of the ignition coil IGI.

As a result, a high voltage is induced in the secondary coil of the ignition coil IGI, a spark is generated in the ignition plug p1, and the first cylinder is ignited. Similarly, when a trigger signal is applied to the thyristor S2, the thyristor S2 becomes conductive, discharging the charge in the capacitor C2 to the primary coil of the ignition coil IG2, and inducing a high voltage in the secondary coil of the ignition coil. This generates a spark in the spark plug P2, and the second cylinder is ignited.

When thyristor Sl or S2 is conducting, the voltage drop between the gate and cathode of each is the ratio.

Input to comparator CMI or 0M2. The voltage across the resistor R15 is input to the non-inverting input terminal of the comparator CM1, and this voltage is lower than the voltage drop between the gate and cathode of the thyristor.

Therefore, when the gate-cathode voltage of thyristor S1 is input to the comparator CMI, the output terminal potential of the comparator becomes zero level (ground potential), and the gate-cathode voltage of thyristor S2 is input to the comparator 0M2. and the comparator C
The potential at the output terminal of M2 becomes zero level. Comparator CMI
When either the output of or the output of the comparator CM2 becomes zero level: - Since the transistor T2 is cut off, the transistor TI is cut off, and the battery 11 is disconnected from the exciter coil 10.

When the engine speed is low, the output voltage of the exciter coil 10 in the negative half cycle is lower than the voltage of the battery 11. Therefore, if the transistor TI and the switch control circuit 18 were not provided in this embodiment, the exciter coil 10 would be in the negative half cycle. Battery 1 when outputting half cycle voltage
A current flows from 1 to the ignition main circuits 1 and 2 through the exciter coil 10. Therefore, thyristors St and S2 cannot be cut off, and capacitors CI and C2 cannot be charged. Therefore, in this embodiment, the switch control circuit 1
8 is provided so that when the thyristors Sl and S2 are conductive, the transistor Tl is held in a cut-off state to disconnect the battery 11 from the exciter coil.

In this embodiment, after the engine has started, the control circuit 3 generates the turn-off command signal Vto when the rotational speed of the engine exceeds a set value and the exciter coil output voltage becomes sufficiently high. Therefore, transistor T4 becomes conductive and transistors T2 and T1 are turned off. This disconnects the battery 11 from the exciter coil 10. When the battery 11 is disconnected from the exciter coil 10, the exciter coil 10 → transistor T3 - resistor R6 → diode D6 → exciter coil 1
The short circuit current of the exciter coil flows through the path 0. Therefore, the ignition of the engine is carried out without any problem.

As described above, in this embodiment, when the rotational speed of the engine exceeds the set value and the exciter coil generates a sufficiently high voltage, the
Since it is cut off and the tsuku soteri is separated from the exciter coil, wasteful consumption of the no(soteri) can be prevented.

In the embodiment shown in FIG. 1, the turn-off circuit 17 may be omitted.

FIG. 4 shows a conventional ignition device that uses the same exciter coil with a reduced number of turns and does not superimpose the short-circuit current of the exciter coil C2) and the output current of the battery, and an ignition device according to the present invention shown in FIG. (1) The figure shows a comparison of the charging voltage of the ignition energy storage capacitor at each rotational speed of the engine. In the conventional ignition system, when the engine rotational speed reaches 86 Orpm, the interruption of the short-circuit current of the exciter coil is started and the ignition operation is started.In contrast, According to the present invention, when the rotational speed of the engine reaches 20 rpm, the interruption of the short circuit current of the exciter coil is started, and the ignition operation is started.According to the present invention, the charging voltage of the capacitor in the region of 2000 rpm or less is started. It has become clear that it is possible to significantly increase the ignition performance at low speeds.

FIG. 2 shows another embodiment of the present invention. In this example, the ignition main circuit 2 for the second cylinder and the pulsar coil for the second cylinder used in the embodiment of FIG. 5 is omitted. In this embodiment, the base of a transistor TI constituting a battery input switch is connected to one end of an exciter coil 10 via a resistor R20. When the exciter coil 10 induces a positive half-cycle voltage, a base current is applied to the transistor TI through the resistor R20, making the transistor conductive.
is connected to the exciter coil 10. When the engine is stopped and the exciter coil is not inducing a voltage, and when the exciter coil is inducing a negative half-cycle voltage, the transistor TI is in a cut-off state.
Battery 11 is disconnected from exciter coil 10. Therefore, wasteful consumption of one battery is prevented. Also, since the battery is disconnected from the exciter coil when the exciter coil induces a negative half-cycle voltage,
Turning off the thyristor Sl takes place without any problems. Therefore, the switch control circuit 1 used in the embodiment of FIG.
8 is omitted.

In this embodiment as well, as shown by the broken line in the figure, a turn-off circuit 17 is provided that turns off the transistor TI when the engine speed exceeds a set value, so that the exciter coil generates a sufficiently large output. The battery 11 may be disconnected when the In this case, a diode D6 is connected in parallel to the series circuit of the battery input switch 12 and the battery 11 in such a direction that the battery voltage is applied in the opposite direction.

FIG. 3 shows still another embodiment of the present invention, in which the battery input switch is omitted and the positive terminal of the battery 11 is connected to the key switch SW and the diode D5.
is connected to the other end of the exciter coil 10 through.

In this example, the peak of the output voltage of the exciter coil 10 is higher than the voltage of the battery 11 when the engine is running at low speed. Therefore, in the negative half cycle of the exciter coil 10, the induced voltage of the exciter coil 10 blocks current from the battery, and the thyristor S1 is turned off.

In the embodiments shown in FIGS. 1 to 3, if battery consumption while the engine is stopped is not a problem,
The key switch SW can be omitted.

[Effects of the Invention] Since the output current of the battery is superimposed on the short-circuit current of the coil, the current cutoff value can be increased even when the output voltage of the exciter coil is low when the engine is running at low speed. Therefore, even if the number of turns of the exciter coil is reduced, a sufficiently high voltage can be induced in the exciter coil when the engine is running at low speeds, and there is an advantage that sufficient ignition performance can be obtained when the engine is running at low speeds.

Further, according to the present invention, since the number of turns of the exciter coil is small, it is possible to prevent the short-circuit current of the exciter coil from becoming excessive in a region exceeding the set rotational speed, and it is possible to reduce heat generation.

Further, according to the present invention, unlike a battery-type capacitor discharge type ignition device, a transformer or an oscillation circuit is not required, so there is an advantage that the configuration of the ignition device can be simplified.

In particular, according to the invention described in claim 3 or 5, a battery input switch is provided between the exciter coil and the battery, and the switch is cut off when the rotational speed of the engine exceeds a set value. Therefore, the battery can be disconnected in the rotation range above the engine's set rotation speed,
This can prevent unnecessary battery consumption.

[Brief explanation of the drawing]

Figures 1 to 3 are circuit diagrams showing different embodiments of the present invention, and Figure 4 compares the capacitor charging voltage when the same exciter coil is used in the ignition device of the present invention and the conventional ignition device. FIG. 1.2... Ignition main circuit, C1, C2... Ignition energy storage capacitor, Sl, S2... Thyristor,
10... Exciter coil, 11... Battery, 1
2...Battery input switch, 13...Trigger circuit for switch 12, 14...Short circuit switch, 15.
... Cutoff circuit, 17... Turn-off circuit, 18...
Switch control circuit. Figure 4 Engine rotation speed N [x10'rpm]

Claims (5)

[Claims] (1) An exciter coil installed in the magnet generator,
A battery connected in series with the exciter coil, and an output of one half cycle of a polarity in which the exciter coil is connected in parallel with the series circuit of the exciter coil and the battery, and the exciter coil adds to the voltage of the battery. A current interrupting type booster circuit having a shorting switch that conducts when a voltage is generated and a cutoff circuit that turns the shorting switch into a cutoff state when the current flowing through the shorting switch reaches a predetermined value; and the shorting circuit. A capacitor discharger comprising a capacitor that is charged with a voltage induced in an exciter coil when a switch is cut off, and a thyristor that conducts at the ignition position of an internal combustion engine and discharges the charge of the capacitor to the primary coil of the ignition coil. Ignition system for internal combustion engines. (2) A battery input switch is inserted between the exciter coil and the battery, and a trigger circuit is provided that makes the battery input switch conductive when the exciter coil generates an output voltage of one half cycle. The ignition device for a capacitor discharge type internal combustion engine according to claim 1. (3) A diode is connected in parallel to the series circuit of the battery input switch and the battery, and the diode is oriented so that the battery voltage is applied in the opposite direction, and when the rotational speed of the internal combustion engine exceeds the set value. 3. The capacitor discharge type ignition device for an internal combustion engine according to claim 2, further comprising a turn-off circuit for turning off the battery input switch. (4) A battery input switch that conducts when a trigger signal is applied at the voltage of the battery is inserted between the exciter coil and the battery, and cuts off the battery input switch when the discharge thyristor is conductive. 2. A switch control circuit for controlling the battery, wherein a diode is connected in parallel to the series circuit of the battery input switch and the battery, the diode being oriented so that the voltage of the battery is applied in the opposite direction. The capacitor discharge type internal combustion engine ignition device described in . (5) The capacitor discharge type ignition device for an internal combustion engine according to claim 4, further comprising a turn-off circuit that turns off the battery input switch when the rotational speed of the internal combustion engine exceeds a set value.