JPS6026167A - Contactless igniter for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent a capacitor from being overcharged, by short-circuiting the terminals of the capacitor through a short-circuiting semiconductor switching element when the charged voltage of the capacitor is higher than a prescribed level, to keep a high voltage from being induced. CONSTITUTION:In the medium and high speed revolution of an engine, the charged voltage of a capacitor 13 becomes higher than a set level and the potential of the voltage division point between voltage dividing resistors 9, 10 rises, when a second high voltage is induced across a charging coil 1, so that a transistor 6 is turned on and the base of another transistor 8 is short-circuited. As a result, the transistor 8 is not turned on even if a third and other succeeding forward half rectification outputs are generated across the charging coil 1, so that a high voltage is not induced across the coil any more. Consequently, the capacitor 13 is not charged any more. The capacitor 13 is thus prevented from being overcharged.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitor discharge type non-contact ignition device for an internal combustion engine.

Conventionally, as described in Japanese Unexamined Patent Publication No. 57-131864, the output of a capacitor charging coil of a magnet generator is short-circuited by a short-circuiting semiconductor switching element, and when this switching element is cut off, the charging coil is By charging the capacitor by the high voltage induced in the
It is known that a charging coil with a thick wire diameter and a small number of turns is used to charge a condenser.

However, when the above-mentioned conventional method is applied to a multi-pole magnet optical FFI machine of 4 @ or more, for example, a high voltage is induced every time a half-wave output on the capacitor charging side is generated in the capacitor charging coil, and the capacitor is Since multiple charging is performed using the 7ii voltage, the charging voltage of the capacitor becomes too high, and there is an upper gap in the withstand voltage of each element.

Therefore, in order to solve the above-mentioned problem, the present invention conducts a cut-off control semiconductor switching element that short-circuits the control signal of the short-circuit semiconductor switching element when the charging voltage of the capacitor exceeds a predetermined value. It is an object of the present invention to prevent the generation of an induced high voltage after a capacitor charging voltage exceeds a predetermined value, and to prevent overcharging of a capacitor with a simple configuration.

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

First, in FIG. 1, °ζ, 1 is a capacitor charging coil of a multi-pole magnet generator, for example, a wire diameter of 0.3 to 1.0 and a number of turns of 200 to 600 is used.

2 is a timing sensor that generates an output signal at a reference position, 4 and 5 are voltage dividing resistors connected in series between the terminals of the capacitor charging coil 1, and the voltage dividing point a is connected to the transistor 6.
It is connected to the base. This transistor 6 is connected between the base and emitter of the transistor 8. 7 is a base resistance of the transistor 8, and 19 is a capacitor connected in parallel to the resistor 5. This capacitor 19 and the resistors 4 and 5 constitute a first detection circuit. Further, the transistor 6 constitutes a semiconductor switching element for cut-off control that short-circuits the base of the transistor 8, and the transistor 8 constitutes a semiconductor switching element for short-circuiting that short-circuits the forward output of the coil I. 13 is an ignition capacitor; 9. 10 is a voltage dividing resistor connected to a capacitor 13, and its voltage dividing point is connected to the base of the transistor 6 via a diode 11.

12 is a discharge blocking diode, 14 is a diode that short-circuits the negative half output of the timing sensor 2, I5 is a DC arc diode, 16 is an ignition coil, 16a is its primary coil, and 16b is its secondary coil. 17 is an ignition plug, 18 is an ignition switch which is a semiconductor switching element for ignition, and conducts when the ignition signal from the timing sensor 2 is applied to the gate, and the capacitor 13
This charge is supplied to the primary coil 16a of the ignition coil 16. 20 is a diode for blocking backflow. .

Next, the structure of the magnet generator used in this example will be explained. In FIG. 2, 30 is a bowl-shaped rotor, and 31 is a ring-shaped main magnet fixed to the inner circumferential surface of the rotor 30, which is magnetized with 12 poles alternately <N and S at equal intervals as shown in the figure. 3
Reference numeral 2 denotes a ring-shaped stator core fixed to the side wall of the internal combustion engine, and twelve protrusions 32a to 324 are formed at equal intervals on the outer periphery of the stator core. 33 are ten protrusions 32c to 3
21, each having a number of turns and connected in series with each other, and serves as a power source for a load such as a lamp. A boss 34 is fixed to the crankshaft of the internal combustion engine by a bottle (not shown), and the rotor 30 is fixed to the boss 34 via a rivet (not shown). 35 is an ignition signal timing sensor fixed to the side wall of the internal combustion engine on the outer periphery of the rotor 30, and includes a permanent magnet 3 magnetized in the radial direction.
5a, a core 35b fixed to this permanent magnet 35a, and a sensor coil 2 wound around the core 35b.

Reference numeral 36 denotes a projection made of a magnetic material provided on the outer circumference of the rotor 30. A core 35b is provided at a position facing this projection 36, and a change in magnetic flux caused by the core 35b and projection 36 facing each other causes the sensor coil to Figure 3 ([11
An output voltage shown by is generated.

The capacitor charging coil l has two protrusions 32a and 32b.
The main magnets 31 are wound around each other and connected in series with each other, and as shown in FIG. 3 (al), six cycles of no-load AC voltage are generated in the capacitor charging coil 1 by the rotation of the main magnet 31 for each rotation of the rotor of the magnet generator.

Now, when a half-wave output in the direction of the arrow (positive direction) in Fig. 1 begins to occur in the charging coil L, a base current flows to the transistor 8 in the base-emitter ground circuit of the coil 1, the resistor 7, and the transistor 8. The collector and emitter of this transistor 8 are electrically connected, and the output of the coil 1 is short-circuited. At this time, due to the increase in the short-circuit current of the transistor 8 shown in FIG. 3 (dl), the collector of the transistor 8
The voltage drop between the emitters increases, and the voltage at the connection point a of the voltage divider circuit made up of resistors 4 and 5 increases. When this voltage reaches a set value (for example, a voltage value corresponding to a short circuit current of 0.5 to 4 A), transistor 6 becomes conductive and short-circuits between the base and emitter of transistor 8, so that the voltage between the collector and emitter of transistor 8 is 0FFL. , the short circuit current is suddenly cut off. At this time, a large induced voltage is generated in the coil l, as shown by the solid line in Figure 3 (bl), and this high voltage causes the capacitor 13 to
- Capacitor 13 - Diode 15 - Ground circuit,
Charge the battery sufficiently as shown by the solid line or broken line in FIG. 3 fcl.

Here, if the high voltage induced in the charging coil 1 is relatively low, such as when the engine speed is low, the voltage charged to the capacitor 13ζ will not exceed the set value, so as shown in FIG. 3(b). The capacitor 13 is charged multiple times as shown by the solid line in FIG. 3 (C1) by the high voltage of the charging coil 1 that is generated six times per rotation of the magnet generator.

On the other hand, when the engine rotates at medium to high speeds, the high voltage induced in the charging coil 1 becomes relatively high. When the charging voltage of the content 913 becomes lower than the set value due to the high voltage, the potential at the voltage dividing point of the voltage dividing resistor 9.10 becomes a value sufficient to make the transistor 6 conductive. , this transistor 6 is made conductive and the base of the transistor 80 is short-circuited.As a result, even if the third and subsequent positive half-wave forces are generated in the charging coil 1, the transistor 8 is not made conductive and the charging coil 1 is not damaged. A high voltage is not induced, and therefore, the capacitor I3 is not charged thereafter, and overcharging of the capacitor 13 is prevented.At this time, the output voltage of the charging coil 1, the charging voltage of the capacitor 13, and the voltage of the transistor 8 The short circuit current is shown in Figure 3 (bl, (cl)
, (indicated by the dashed lines of di, respectively.

In addition, it is possible to reduce the number of times the transistor 8 is turned on and off when the high voltage induced in the charging coil l is relatively high, such as when the engine is running at high speed.
ζ, the heat generation of the transistor 80 can be suppressed and thermal runaway can be prevented.

Also, when the ignition timing comes, the timing sensor 2 shown in Figure 3 (
The thyristor 18 becomes conductive due to the ignition signal indicated by Ql.
The charge in the capacitor 13 is rapidly discharged in the circuit of the capacitor 13 → thyristor 18 → ground and the primary coil 16a of the ignition coil 16, and the secondary coil 1 of the ignition coil 16
A high voltage of 1υ is applied to 6b to generate an ignition spark at the ignition plug 17.

Note that in the embodiment shown in FIG. 1, instead of the resistors 9 and 10 and the diode 11, a second detection circuit consisting of a series circuit of a Zener diode and a resistor is connected directly to the charging side terminal of the capacitor 13 and a in FIG. ff11. It may be inserted between the points. In this way, leakage of the capacitor charging charge to the resistor 9 side at low speeds can be eliminated, and a drop in the charging voltage of the capacitor 13 can be prevented.

FIG. 4 shows another embodiment of the device of the present invention (showing
f11 In contrast to the embodiment shown in FIG. 11, a diode 14 is connected in series with the timing coil 2, a transistor 22 is connected in parallel between the gate and cathode of the thyrisk 18, and the base of this transistor 22 and the charging side terminal of the capacitor 13 are connected. A series circuit of a resistor 26 and a diode 21 is connected between the resistor 26 and the diode 21, and a series circuit of each diode 23a to 23c and each switch 24a to 24c is connected between the connection point of the diode 2 and the resistor 26 and the ground. It is a circuit that is connected.

As each of these switches 24a to 24c, for example, 2
ON when the side stand of a wheeled vehicle is retracted.
One that turns on when the transmission is in the neutral position, and one that turns on when the clutch is disengaged.

According to this embodiment, if any one of the switches 242 to 24C is ON, the base current of the transistor 22 flows between each of the diodes 232 to 23c and each of the switches 248 to 24C.
4c, the transistor 22 remains OFF, and the ignition signal of the timing coil 2 is applied to the gate of the thyristor 18 via the diode 14, similar to the embodiment shown in FIG. The ignition operation is performed.

Here, if all of the switches 248 to 24C are OFF, the charge of the capacitor 13 is applied to the base of the transistor 22 via the resistor 26 and the diode 21, and the transistor 22 becomes conductive.
bypass the gate signal. As a result, the thyristor 18
The ignition signal is no longer applied to the ignition, the ignition operation stops,
The engine stops. At this time, several half-wave outputs on the capacitor charging side are generated in the capacitor charging coil ■ until the engine stops, but when the charging voltage of the capacitor 13 exceeds a predetermined value, the transistor 8 turns on and the 0FFL is no longer turned on, so the capacitor 13 is never overcharged.

In the embodiment of FIG. 4, instead of connecting the transistor 22 in parallel with the gate circuit of the thyristor 18, the transistor 25 can also be connected in series with the gate circuit of the thyristor 18, as shown by the broken line. In this case,
The resistor 26 and diode 21 can be omitted.

In addition, in FIG. 4, for the timing coil 27,
As shown by the broken line, the engine stop manual switches 27 may be connected in parallel.

As shown in Fig. 4, in a system that shuts off the application of the ignition signal to the gate of the SIRISK 18 to disable ignition and stop the engine, or in a system that prevents the engine from running, there are two poles. Even when a magnet generator is used, overvoltage of the capacitor 13 can be prevented when the engine is stopped.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing one embodiment of the device of the present invention, and FIG.
The figure is a bottom view showing a magnet generator applied to the device shown in FIG. 1, FIG. 3 is a waveform diagram of each part used to explain the operation of the device shown in FIG. 1, and FIG. 4 is a diagram showing another embodiment of the device of the present invention. First is an electrical circuit diagram. ■... Capacitor charging coil, 2... Timing sensor forming the ignition signal generation circuit, 4,5.19...
A voltage dividing resistor, a capacitor, and a 6.
...Transistor constituting the semiconductor switching element for cut-off control, 8...Thyristor constituting the semiconductor switching element for short circuit, 9, 10.11...Voltage dividing resistor and diode constituting the second detection circuit, 13. ...Capacitor, 16...Ignition coil, 16a...Primary coil, 1
6b...Secondary coil, 17...Ignition plug, I8...
Ignition thyristors are semiconductor switching elements for ignition. Representative Patent Attorney Takashi Okabe

Claims (2)

[Claims] (1) A capacitor charging coil of a magnet generator, a short-circuit semiconductor switching element that substantially shorts the half-wave output of one of the charging coils, and a cut-off control semiconductor that short-circuits the control signal of this short-circuit semiconductor switching element. a switching element; a first detection circuit for making the semiconductor switching element for cutoff control conductive when a short circuit current is sufficiently flowing through the semiconductor switching element for shorting; and a first detection circuit for making the semiconductor switching element for cutoff control conductive when the semiconductor switching element for shorting is cut off; a capacitor charged by a high voltage induced in the
an ignition coil having a primary coil and a secondary coil; a second detection circuit for detecting a charging voltage of the capacitor and making the cutoff control semiconductor switching element conductive when the voltage exceeds a predetermined value; an ignition signal generation circuit that generates an ignition signal at the appropriate timing; and an ignition semiconductor switching element that is electrically connected by the ignition signal from the ignition signal generation circuit and supplies the charge in the capacitor to the primary coil of the ignition coil. and an ignition plug connected to a secondary coil of the ignition coil. (2) The non-contact ignition device for an internal combustion engine according to claim 1, wherein the magnet generator is a multi-pole magnet generator with four or more poles.