JPH0222236B2 - - 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 a full-wave rectified voltage is used to charge the ignition energy storage capacitor, there is an advantage that the capacitor can be charged efficiently, but on the other hand, when the discharge control thyristor conducts, the discharge current of the capacitor increases. The output current of the full-wave rectifier circuit flows through the thyristor before the current drops below the holding current of the thyristor, making it difficult to turn off the discharge control thyristor and making it impossible to recharge the capacitor. In order to eliminate this drawback, in a device that uses a transistor oscillation type DC-DC converter as a power source for charging the ignition energy storage capacitor, the DC-DC converter is used for a short period of time after the ignition signal is applied to the discharge control thyristor. -There is a device that stops the oscillation of the DC converter (for example, Japanese Patent Application Laid-open No. 80435/1983). 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 is periodically interrupted while the magnet generator is rotating. 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.

OBJECT OF THE INVENTION An object of the invention is to fully rectify the alternating current output voltage of an exciter coil provided in a magnet generator so that the discharge control thyristor can be reliably disconnected even if the ignition energy storage capacitor is charged. An object of the present invention is to provide a capacitor discharge type internal combustion engine ignition device.

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 circuit connected between both terminals of the exciter coil to output a full-wave rectified voltage; and an ignition energy storage capacitor provided on the primary side of the ignition coil and charged to one polarity by the full-wave rectified voltage. and a discharge control thyristor provided to discharge the electric charge of the capacitor to the primary coil of the ignition coil when conductive, and a signal supply circuit that provides an ignition signal to the thyristor at the ignition position of the engine. A capacitor discharge type internal combustion engine ignition device,
Further, a shorting switch circuit is connected between the DC output terminals of the full-wave rectifier circuit and controlled by a thyristor firing signal from the signal supply circuit to substantially short-circuit the DC output terminals of the full-wave rectifier circuit. It is configured. The conduction period of the short circuit switch circuit is selected to continue at least until the capacitor discharge current due to conduction of the thyristor falls below the holding current of the thyristor and the thyristor is turned off.

With the above configuration, the output current of the full-wave rectifier circuit will not flow through the thyristor before the capacitor discharge current flowing through the thyristor falls below the holding current of the thyristor, so the thyristor can be turned off reliably. be able to.

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 circuit 4 is grounded. The cathode of the diode 5 is connected to one end of an ignition energy storage capacitor 6, and the other end of this capacitor is connected to the non-ground terminal of the primary coil 2a of the ignition coil and to the anode of a 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 is the signal supply circuit 10
The non-ground terminal 10a of the thyristor 8 is connected to the gate of the thyristor 8. The above circuit constitutes a capacitor discharge type ignition device, and the AC voltage induced in the exciter coil 1 is rectified by the single-phase full-wave rectifier circuit 4, and the DC output voltage is changed from the positive output terminal 4c of the rectifier circuit 4 to the diode 5 to Capacitor 6 → damper diode 7 and primary coil 2 of ignition coil
The capacitor 6 is charged to the polarity shown in the figure through a path from a to the negative output terminal 4d 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 electric charge in the capacitor 6 is discharged through the thyristor 8 to the primary coil 2a of the ignition coil 2. 2
The engine is ignited by the spark plug 4 due to the high voltage induced in the secondary coil 2b.

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 15 and 16, and the anode of the Zener diode 17 is connected to the diode 1 whose cathode is connected to the base of the transistor 13.
8 anodes. Resistor 15 above
and 16, a Zener diode 17, and a diode 18 constitute a voltage detection circuit 19, which 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. Also, the transistor 13 and the resistor 14
and the voltage detection circuit 19 constitute a control circuit 20 that controls the voltage between the DC output terminals 4c and 4d of the full-wave rectifier circuit 4. The middle transistor 13 conducts to short-circuit 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 to short-circuit the DC output of the full-wave rectifier circuit 4. The DC output voltage of the full-wave rectifier circuit 4 is made conductive and the magnitude of the DC output voltage of the full-wave rectifier circuit 4 is limited 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 fixing four permanent magnets 32, 32... to the inner peripheral wall of a bowl-shaped flywheel 31 made of a magnetic material, arranged at equal intervals. The flywheel 31 is magnetized in the radial direction so that the magnetic poles on the sides 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 attached to the engine by fitting the boss 33 onto the rotating shaft of the engine. The stator 40 is constructed by arranging I-shaped iron cores 41 and 42 having magnetic pole portions at both ends, wound with an exciter coil 1 and a generating coil 43, respectively, 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. Also flywheel 31
A small permanent magnet 34 magnetized in the radial direction is fixed to the outer periphery of the magnet 34 by adhesive or the like, and the signal coil 11 is wound around an iron core 44 that is fixedly placed at a position facing the permanent magnet 34 with an air gap therebetween. . In the example shown in FIG. 2, when the magnet rotor 30 rotates once, the generator coil 1
Two cycles of alternating current voltage are induced in the signal coil 11, and one cycle of pulse voltage is induced in the signal coil 11 when the permanent magnet 34 passes through the magnetic pole portion of the iron core 44.

Next, the operation of the above embodiment will be explained. When the magnet rotor 30 in FIG. 2 rotates, the exciter coil 1
, a voltage V _ep is induced which exhibits 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 a full-wave rectified voltage _VRO having a no-load waveform shown by a chain line in FIG. 3b appears at the positive output terminal 4c of the full-wave rectifier circuit 4. 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 magnetically charged as 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 having the waveform shown in FIG. 3c is sent from the signal coil 11.
When V _S 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 charge of the capacitor 6 charged to the voltage V _C passes through the thyristor 8. The primary coil 2a of the ignition coil 2 is suddenly discharged. At this time, the waveform of the discharge current i ₁ passing through the thyristor 8 is as shown in FIG. 3f. When the discharge current of the capacitor 6 suddenly flows through the primary coil 2a, a high voltage is induced in the secondary coil 2b of the ignition coil 2, and the spark plug 3
A spark flies and ignites the engine. In the ignition device of the present invention, the ignition signal V _S generated in the signal coil 11 is also applied to the base of the transistor 13, and when the ignition signal V _S reaches the trigger level V _t of the transistor 13 at time _t1 . This transistor 1
3 becomes conductive and the DC output terminal 4c of the full-wave rectifier circuit 4
Short-circuit the voltage V _R. The value of the ignition signal V _S is at time t ₃
When the voltage falls below the trigger level V _t of the transistor 13 again, the transistor 13 becomes non-conductive again and the short circuit of the DC output terminal 4c 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 _VR 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, the period T _S during which the output voltage of the full-wave rectifier circuit 4 is short-circuited is approximately T _S = t ₃ - _{t 2} . Become. Incidentally, the cascade time T (see Fig. 3 f) of the discharge current i ₁ passing through the thyristor 8 due to the charge of the capacitor 6 when the thyristor 8 is turned on is determined by the inductance of the primary coil 2a and secondary coil 2b of the ignition coil, respectively.
L ₁ and L ₂ , the capacitance of the ignition energy storage capacitor 6 and the secondary circuit of the ignition coil 2 are respectively C ₁ and C ₂ , the primary coil 2a and the secondary coil 2b
Letting the coupling coefficient and matching coefficient between k and u (=L ₁ C ₁ /L ₂ C ₂ ), respectively, 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 value of the constant of the ignition circuit are set so that T _S −T>(turn-off time of the thyristor 8) within the range. Therefore,
Since 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, there is no fear that the conduction of the thyristor 8 will be sustained by the output current of the full-wave rectifier circuit 4. The thyristor 8 can be cut off and the capacitor 6 can be recharged reliably.

Next, in the medium speed region of the magnet generator's rotation speed,
The no-load output voltage V' _RO and the load output voltage V' _R of the positive output terminal 4c of the full-wave rectifier circuit 4 become high as shown by the chain line and the broken line in FIG. 3b, respectively, and the no-load output voltage becomes high. When the instantaneous value of V′ _R exceeds the predetermined value V _n , 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 voltage value at the DC output terminal 4c of the full-wave rectifier circuit 4 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 _Vn . 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 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 particularly small, as shown by the broken line b in FIG. The voltage increases significantly in the high speed region, 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. Also, the signal coil 1 of the signal supply circuit 10
1 may be provided in a separate signal generator, or a conventionally known photoelectric type or monostable multivibrator type may be used as the signal supply circuit 10. In the above embodiment, a rectifier circuit resulting from a single-phase full-wave bridge 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 using a two-phase half-wave rectifier circuit. It can also be done.

Effects of the Invention As described above, according to the present invention, during the period when the discharge control thyristor is conducting, the output end of the full-wave rectification circuit is short-circuited to perform full-wave rectification for charging the ignition energy storage capacitor. Since voltage is prevented from being applied to the discharge control thyristor, the discharge control thyristor can be reliably turned off and malfunction of the ignition device 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 ignition energy storage capacitor charging voltage with respect to the rotation speed in an embodiment of the present invention. 1... Exciter coil, 2... Ignition coil,
3...Spark plug, 4...Full wave rectifier circuit, 6...
Ignition energy storage capacitor, 5, 7...diode, 8...discharge control thyristor, 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 provided in a magnet generator that rotates in synchronization with the rotation of the internal combustion engine and that 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 circuit 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, and when electrical conduction occurs, the charge of the capacitor is In a capacitor discharge type internal combustion engine ignition system, the capacitor discharge type internal combustion engine ignition device is provided with a discharge control thyristor provided to discharge the ignition coil to the primary coil of the ignition coil, and a signal supply circuit that supplies an ignition signal to the thyristor at the ignition position of the engine. , comprising a shorting switch circuit connected between the DC output terminals of the full-wave rectifier circuit and controlled by a thyristor firing signal from the signal supply circuit to substantially short-circuit the DC output terminals of the full-wave rectifier circuit; A capacitor discharge type internal combustion engine ignition system, wherein the conduction period of the short circuit switch circuit is set to continue at least until the thyristor is turned off.