JPH0226707B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a capacitor discharge type internal combustion engine ignition device that charges an ignition energy storage capacitor by full-wave rectifying the AC output voltage of a magnet generator. be.

Prior art As a capacitor discharge type internal combustion engine ignition system,
A circuit is known in which an AC voltage is full-wave rectified to charge an ignition energy storage capacitor (for example, Japanese Patent Publication No. 43-17135). When using a full-wave rectified output voltage, there is an advantage that the ignition energy storage capacitor can be efficiently charged from the low speed range of the engine, but on the other hand, when the discharge control thyristor conducts, the discharge current of the capacitor increases. The disadvantage is that the output current of the full-wave rectifier circuit flows through the thyristor before the current decreases below the holding current of the thyristor, making it difficult to turn off the thyristor and recharging the capacitor. In order to eliminate this drawback, a transistor oscillation type DC-
Some devices that use a DC converter are designed to stop the oscillation of the DC-DC converter for a short period of time after the ignition signal is applied to the discharge control thyristor (for example,
80435). However, in a device that charges the ignition energy storage capacitor by full-wave rectifying the AC output voltage of an exciter coil installed in the magnet generator, the generation of the AC output voltage while the magnet generator is rotating is periodically interrupted. Since it is not possible to stop the ignition energy for a period of time, conventionally a method has been used in which the alternating current output voltage of the exciter coil is half-wave rectified to charge the ignition energy storage capacitor.

In addition, charging efficiency is good when charging a capacitor by full-wave rectification of the AC output voltage of the exciter coil installed in the magnet generator, so the charging voltage of the capacitor is particularly low in the medium speed rotation region of the magnet generator. This made it necessary to use a capacitor with a high withstand voltage.

OBJECT OF THE INVENTION An object of the present invention is to provide a system that can reliably and quickly disconnect a thyristor for controlling discharge even when an ignition energy storage capacitor is charged by full-wave rectification of the AC output voltage of an exciter coil provided in a magnet generator. An object of the present invention is to provide a capacitor discharge type internal combustion engine ignition device that can prevent the charging voltage of an ignition energy storage capacitor from becoming excessive.

Structure of the Invention The present invention includes an ignition coil having a primary coil and a secondary coil, an exciter coil that is provided in a magnet generator that rotates in synchronization with the rotation of an internal combustion engine, and that induces an alternating current voltage by the rotation of the engine. a full-wave rectifier connected to an exciter coil to rectify the alternating current output of the exciter coil to output a full-wave rectified voltage; and a full-wave rectifier provided on the primary side of the ignition coil and charged to one polarity by the full-wave rectified voltage. An 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 a signal that provides an ignition signal to the thyristor at the ignition position of the engine. The present invention provides a capacitor discharge type internal combustion engine ignition system comprising a supply circuit, and a short-circuit switch circuit provided to substantially short-circuit the DC output terminals of the full-wave rectifier when conductive. , a voltage detection circuit provided to generate a control output signal when the instantaneous value of the full-wave rectified voltage exceeds a predetermined value, and the short circuit switch circuit is controlled by the control output of the voltage detection circuit to Conductive during a period when a control output signal is generated, and conductive by the thyristor ignition signal from the signal supply circuit to short-circuit the DC output terminals of the full-wave rectifier at least during the period until the thyristor is turned off. It is configured as follows.

With the above configuration, when the rectified output voltage of the full-wave rectifier exceeds a predetermined value, the short circuit switch circuit becomes conductive and limits the rectified output voltage to a predetermined value, thereby preventing excessive voltage from being applied to the ignition energy storage capacitor. Furthermore, while the thyristor ignition signal is being generated, the short circuit switch circuit is conductive and prevents the output voltage of the full-wave rectifier from being applied to the thyristor, so that the thyristor can be turned off reliably.

Embodiments The present invention will be described in detail below along with embodiments thereof with reference to the drawings.

FIG. 1 shows an electric circuit according to an embodiment of the present invention, in which 1 is an exciter coil disposed in a magnet generator that rotates synchronously with the internal combustion engine;
2 is an ignition coil consisting of a primary coil 2a and a secondary coil 2b, and one ends of the primary and secondary coils 2a and 2b of the ignition coil are commonly connected and grounded. Reference numeral 3 denotes a spark plug connected to the secondary coil 2b, and this spark plug is attached to a cylinder of an engine (not shown). One end 1a and the other end 1b of the exciter coil 1 are each connected to a single-phase full-wave rectifier 4.
are connected to AC input terminals 4a and 4b.
A positive output terminal 4c of the single-phase full-wave rectifier 4 is connected to the anode of the diode 5, and a negative output terminal 4d of the full-wave rectifier 4 is grounded. The cathode of the diode 5 is a capacitor 6 for storing ignition energy.
The other end of this capacitor is connected to the non-ground terminal of the secondary coil 2a of the ignition coil and to the anode of the damper diode 7. The cathode of diode 7 is grounded. The anode of a discharge control thyristor 8 is connected to the connection point between the cathode of the diode 5 and the capacitor 6, and the cathode of the thyristor 8 is grounded. A resistor 9 and a signal supply circuit 10 are connected in parallel between the gate and cathode of the thyristor 8. The signal supply circuit 10 is composed of a signal coil 11 provided in a magnet generator and having one end grounded, and diodes 12 and 12' having anodes commonly connected to the other ends of the signal coil 11. The cathode serves as the non-ground terminal 10a of the signal supply circuit 10 and is connected to the gate of the thyristor 8. The above circuit constitutes a capacitor discharge type ignition device, and the exciter coil 1
The AC voltage induced in the is rectified by the single-phase full-wave rectifier circuit 4, and the DC output voltage is output from the positive output terminal 4c of the rectifier circuit 4 → diode 5 → capacitor 6 → damper diode 7 and the primary coil 2a of the ignition coil.
→Charge the capacitor 6 to the polarity shown in the figure through the path of the negative output terminal 7d of the rectifier circuit 4. When an ignition signal is generated from the signal supply circuit 10 at the ignition position of the engine, the thyristor 8 becomes conductive, and the charge in the capacitor 6 passes through the thyristor 8 to the ignition coil 2.
The spark plug 4 is discharged to the primary coil 2a of the spark plug 4 due to the high voltage induced in the secondary coil 2b of the ignition coil.
The engine is ignited.

In the circuit of the above embodiment of the capacitor discharge type ignition device of the present invention, a transistor 13 is further provided between the positive polarity output 4c of the full-wave rectifier circuit 4 and the ground, the collector and emitter of which are respectively connected. The base of the transistor 13 is connected to the non-grounded output terminal 10a of the signal supply circuit 10 and a resistor 14 whose one end is grounded.
connected to the other end. This transistor 1
3 constitutes a short-circuit switch circuit that substantially short-circuits the DC output terminals of the full-wave rectifier circuit 4. A voltage dividing circuit consisting of a series circuit of resistors 15 and 16 is also connected between the positive output terminal 4c of the full-wave rectifier circuit 4 and the ground. The cathode of a Zener diode 17 is connected to the connection point between the resistors 16 and 16, and the anode of the Zener diode 17 is connected to the transistor 1.
Diode 18 whose cathode is connected to the base of 3
the anode is connected. A voltage detection circuit 19 is constituted by the resistors 15 and 16, the Zener diode 17, and the diode 18, and the detection circuit supplies a base current to the transistor 13 when the instantaneous value of the DC output voltage of the full-wave rectifier circuit 4 exceeds a predetermined value. give. The transistor 13, the resistor 14, and the voltage detection circuit 19 are connected to a control circuit 2 that controls the voltage between the DC output terminals 4c and 4d of the full-wave rectifier circuit 4.
0, and during the period when the firing signal of the thyristor 8 is generated in the signal supply circuit 10, the transistor 13
conducts and short-circuits the DC output of the full-wave rectifier circuit 4, and when the instantaneous value of the DC output voltage of the full-wave rectifier circuit 4 rises above a predetermined value, the Zener diode 17 conducts and makes the transistor 13 conductive. , limits the magnitude of the DC output voltage of the full-wave rectifier circuit 4 to a predetermined value.

In the ignition system of the above embodiment, the exciter coil 1 generates an alternating current voltage by the rotation of the magnet generator, and the signal coil 11 generates a pulse voltage once in one ignition cycle of the engine. Figure 2 shows an example of a magnet generator that generates such voltages in the exciter coil 1 and signal coil 11.
This magnet generator consists of a magnet rotor 30 and a stator 40. The magnet rotor 30 is constructed by arranging four permanent magnets 32, 32, . The magnets are magnetized in the radial direction of the flywheel 31 so that the magnetic poles on the inner circumferential side are alternately N and S poles. A boss 33 is provided at the center of the bottom wall of the flywheel 31, and the magnet rotor 30 is fitted onto the rotating shaft of the engine. The stator 40 is composed of I-shaped iron cores 41 and 42 having magnetic pole portions at both ends, each of which is wound with an exciter coil 1 and a power generation coil 43, which are arranged at 180° opposing positions. The power generating coil 43 is used as a low-voltage power source for lighting lamps, charging batteries, and the like. The magnetic pole portions of the iron cores 41 and 42 are respectively arranged to face the inner circumferential magnetic pole of the magnet 32 with an air gap interposed therebetween. In addition, a small permanent magnet 34 magnetized in the radial direction is attached to the outer periphery of the flywheel 31.
The signal coil 11 is wound around an iron core 44 which is fixedly fixed to the iron core 44 by adhesive or the like, and is fixedly disposed at a position opposite to the iron core 44 with a gap therebetween. In the example shown in FIG. 2, when the magnet rotor 30 rotates once, two cycles of AC voltage are induced in the generator coil 1, and the permanent magnet 3
4 passes through the magnetic pole portion of the iron core 44, one cycle of pulse voltage is induced in the signal coil 11.

Next, the operation of the above embodiment will be explained. When the magnet rotor 30 in FIG. 2 rotates, the exciter coil 1
, voltages v _e and _p are induced which exhibit a no-load waveform as shown in FIG. 3a with respect to time t. This voltage is full-wave rectified by the full-wave rectifier circuit 4, and the positive polarity output terminal 4c of the full-wave rectifier circuit 4 receives a full-wave rectified voltage v _R , _O with a no-load wave shown by the chain line in FIG. 3b. appear. This rectified voltage causes a charging current to flow through the diodes 5 and 7 to the ignition energy storage capacitor 6, so the waveform of the load terminal voltage v _R of the positive output terminal 4c of the full-wave rectifier is shown by the solid line in Figure 3b. It becomes like this. The capacitor 6 is charged with the polarity shown in Fig. 1, and the waveform of its terminal voltage V _C is shown in Fig. 3 e.
As shown by the solid line, the voltage rises in a stepwise manner until the charging voltage V _C is reached. At the ignition timing of the engine, an ignition signal v _S with a waveform shown in FIG. 3c is sent from the signal coil 11.
occurs and its instantaneous value reaches the trigger level V _S of the discharge control thyristor 8 at time t ₂ , this thyristor 8 becomes conductive, and the load of the capacitor 6 charged to the voltage V _C passes through the thyristor 8 to the ignition coil. The primary coil 2a of No. 2 is suddenly discharged. At this time, the waveform of the discharge current i ₁ passing through the thyristor 8 is the third
It will look like Figure f. When the discharge current of the capacitor 6 suddenly flows through the primary coil 2a, the 2 of the ignition coil 2
A high voltage is induced in the next coil 2b, and a spark hits the ignition plug 3, igniting the engine. In the ignition device of the present invention, an ignition signal generated in the signal coil 11
v _S is also applied to the base of transistor 13, and when the firing signal v _S reaches the trigger level V _t of transistor 13 at time t ₁ , this transistor 13
conducts and short-circuits the voltage v _R at the DC output terminal 4c of the full-wave rectifier circuit 4. When the value of the ignition signal v _S falls below the trigger level V _t of the transistor 13 again at time t ₃ , the transistor 13 becomes non-conductive again and the short circuit of the DC output terminal 4 c of the full-wave rectifier circuit 4 is released. . That is, during the period (t ₃ -t ₁ ) in which the transistor 13 is conductive by the ignition signal v _S , the output voltage v _R of the full-wave rectifier circuit 4 is substantially short-circuited and becomes zero. Since the time t ₁ at which the transistor 13 conducts and the time t ₂ at which the thyristor 8 conducts are approximately equal,
Period during which the output voltage of full-wave rectifier circuit 4 is short-circuited
T _S is approximately T _S = t ₃ − _{t 2} . By the way, the duration T of the discharge current i ₁ passing through the thyristor 8 due to the charge of the capacitor 6 when the thyristor 8 becomes conductive (FIG. 3f)
are the inductances of the primary coil 2a and secondary coil 2b of the ignition coil, L ₁ and L ₂ respectively, the ignition energy storage capacitor 6 and the ignition coil 2.
Let the capacitances of the secondary circuits be C ₁ and C ₂ , respectively.
The coupling coefficient and matching coefficient between the primary coil 2a and the secondary coil 2b are k and u (=
L ₁ C ₁ /L ₂ C ₂ ), it can be approximately expressed by the following equation.

In the ignition system of the present invention, the relationship between the value of the period T _S during which the output of the full-wave rectifier circuit 4 is short-circuited and the value of the duration T of the discharge current i ₁ passing through the thyristor 8 is within the operating speed range of the engine. The pulse width of the ignition signal v _S from the signal coil 11 and the constant value of the ignition circuit are set so that T _S −T>(turn-off time of the thyristor 8) within the range. Therefore, the output voltage of the full-wave rectifier circuit ₄ rises again only after the discharge current i 1 passing through the thyristor 8 ends, so that the output voltage of the full-wave rectifier circuit 4 maintains the conduction of the thyristor 8. The thyristor 8 can be cut off and the capacitor 6 can be recharged without fear.

Next, in the medium speed region of the magnet generator's rotation speed,
The no-load output voltage v _R , _O ′ and the loaded output voltage v _R ′ of the positive output terminal 4 c of the full-wave rectifier circuit 4 are as shown in FIG. 3b.
When the instantaneous value of the load output voltage v _R ' exceeds the predetermined value V _n as shown by the chain line and the broken line, respectively, the Zener diode 1 of the voltage detection circuit 19
The voltage applied to the transistor 1 reaches the Zener level, and the Zener diode 17 becomes conductive, causing the transistor 1 to become conductive.
Supply the base current to 3. Therefore, the transistor 13 becomes conductive and the DC output terminal 4 of the full-wave rectifier 4
The value of the voltage of c is limited to V _n . In this case, the waveform of the terminal voltage v _C ' of the capacitor 6 is as shown by the broken line in FIG. 3d, and the value of the charging voltage is limited to V _n . Figure 4 shows the charging voltage of capacitor 6.
Regarding the characteristic of V _C with respect to the rotation speed N, in the case of the above embodiment, the value of V _C is limited to a constant value V _n in the medium speed region as shown by the solid line curve a. In the case of a conventional capacitor discharge type ignition device that does not have the voltage detection circuit 19 and the transistor 13 as a short-circuit switch circuit, the charging voltage V _C of the capacitor 6 is as shown by the broken line b in FIG. This becomes extremely high especially in the medium speed range, and the capacitor 6 needs to have a high withstand voltage.

In the above embodiment, the ignition energy storage capacitor 6 is provided in series with the primary coil 2a of the ignition coil, and the discharge control thyristor 8 is provided in parallel with the series circuit of the capacitor 6 and the primary coil 2a. However, the capacitor discharge type ignition circuit only needs to discharge the electric charge of the capacitor 6 to the primary coil 2a when the thyristor 8 becomes conductive.For example, in FIG.
It is also possible to swap the positions of the thyristor 8 and the thyristor 8. Further, the damper diode 7 can be omitted.

Further, in the above embodiment, the voltage detection circuit 19 is configured by the voltage dividing resistors 15 and 16 and the Zener diode 17 and the diode 18. It may be directly connected between the positive output terminal 4c and the base of the transistor 13. Further, in the above embodiment, the magnet generator has a four-pole configuration, but any multi-pole generator with two or more poles can be used. Further, the signal coil 11 of the signal supply circuit 10 may be provided in a separate signal generator, or a conventionally known photoelectric type or monostable multivibrator type can be used as the signal supply circuit 10. In the above embodiment, a single-phase full-wave bridge-connected rectifier circuit is used as the full-wave rectifier circuit 4, but an intermediate terminal is provided in the exciter coil 1 to obtain a full-wave rectified output by a two-phase half-wave rectifier circuit. It can also be done.

Effects of the Invention As described above, according to the present invention, when the rectified output voltage of the full-wave rectifier exceeds a predetermined value, the short-circuit switch circuit becomes conductive and limits the rectified output voltage to the predetermined value. Therefore, capacitors with low withstand voltage can be used. Furthermore, while the thyristor ignition signal is being generated, the short circuit switch circuit is conductive and prevents the output voltage of the full-wave rectifier from being applied to the thyristor, so the thyristor can be turned off reliably and the ignition device can be turned off. Malfunctions can be prevented.

[Brief explanation of drawings]

Fig. 1 is a connection diagram showing a circuit of an embodiment of the present invention, Fig. 2 is a front view showing an example of a magnet generator used in the invention, and Fig. 3 shows voltages at various parts of the embodiment of Fig. 1. and a current waveform diagram. FIG. 4 is a diagram showing the characteristics of the charging voltage of the ignition energy storage capacitor with respect to the rotational speed for the ignition device of the present invention and the conventional ignition device. 1... Exciter coil, 2... Ignition coil,
3...Spark plug, 4...Full wave rectifier, 6...Ignition energy storage capacitor, 5, 7...Diode, 8...Thyristor for discharge control, 10...Signal supply circuit, 13...Transistor (short circuit) switch circuit), 19... voltage detection circuit, 20... short circuit control circuit.

Claims (1)

[Claims] 1. An ignition coil, an exciter coil that is provided in a magnet generator that rotates in synchronization with the rotation of the internal combustion engine and induces an alternating current voltage by the rotation of the engine, and an exciter coil that is connected to the exciter coil and rectifies the alternating current output of the exciter coil. a full-wave rectifier that outputs a full-wave rectified voltage; and an ignition energy storage capacitor that is provided on the primary side of the ignition coil and is charged to one polarity with the full-wave rectified voltage; In a capacitor discharge type internal combustion engine ignition system, comprising: a discharge control thyristor provided to discharge a primary coil of an ignition coil; and a signal supply circuit that supplies an ignition signal to the thyristor at an ignition position of the engine. , a short-circuit switch circuit provided to substantially short-circuit between the DC output terminals of the full-wave rectifier when conductive; and a short-circuit switch circuit that generates a control output signal when the instantaneous value of the full-wave rectified voltage exceeds a predetermined value. and a voltage detection circuit provided as shown in FIG. A capacitor discharge type internal combustion engine ignition device, characterized in that the DC output terminals of the full-wave rectifier are short-circuited at least during a period until the thyristor is turned off when the thyristor is turned on by a signal.