JPH0439415Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ignition device for an internal combustion engine that performs ignition operation by controlling the primary current of an ignition coil using a transistor switch.

[Prior Art] In general, in general-purpose small internal combustion engines with a displacement of 40 c.c. or less, the magnet generator attached to the engine is also required to be configured as small as possible in order to reduce the size of attached equipment attached to the engine. There is. Therefore, only an ignition coil is provided in the magnet generator, and a transistor-controlled primary current control circuit is connected to the primary coil of the ignition coil to constitute an ignition device.

In this way, small internal combustion engines do not have a generator coil other than the ignition coil in the magnet generator, so they are not equipped with a battery, and a recoil start method is used as the starting method for the engine.

[Problems to be solved by the invention] However, with the recent appearance of small, high-output batteries, consideration has been given to adopting a starting method using a starter motor. When installing a starter motor in this way, it is necessary to be able to charge the battery with the output of the magnet generator, but if a generator coil for charging the battery is provided inside the magnet generator, the magnet generator will become larger. , the weight of the engine increases, which is undesirable. In particular, for equipment that must be carried by hand, such as brush cutters and portable engine generators, it is necessary to reduce the weight as much as possible, so it is necessary to avoid increasing the size of the magnet generator. No. In order to charge the battery without increasing the size of the magnet generator, it is necessary to extract the charging output of the battery from within the internal combustion engine ignition system.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ignition device for an internal combustion engine that can extract charging output from a battery.

[Means for Solving the Problems] The present invention provides at least a primary coil in a magnet generator driven by an internal combustion engine, and applies positive and negative half-cycle voltage to the primary coil in synchronization with the rotation of the engine. An ignition coil that generates a An ignition system for an internal combustion engine is battery charged, the ignition system for an internal combustion engine having a circuit and a cutoff control circuit that cuts off a transistor switch circuit when the voltage across the primary coil reaches a predetermined level during a positive half cycle of the primary coil. It has a function.

Therefore, in the present invention, attention is paid to the voltage drop that occurs across the resistor provided in the transistor switch circuit in the ignition device, and the voltage that occurs across the resistor is applied to the battery.

In the present invention, of the two half cycles of the alternating current voltage induced in the primary coil of the ignition coil, the half cycle in which the ignition operation is performed is defined as the positive half cycle.

[Operation of the invention] If the voltage drop that occurs across the resistor provided in the transistor switch circuit is applied to the battery as described above, the battery can be charged without providing a battery charging coil in the magnet generator. This makes it possible to charge the battery without changing the specifications of the magnet generator used in the recoil start type engine.

[Example] Figure 1 shows the first example of the present invention.
In the figure, reference numeral 1 denotes an ignition coil having a primary coil 1a and a secondary coil 1b, and the ignition coil 1 is arranged in a magnet generator as shown in FIG. This magnet generator 1 has a recess 2a provided on the outer periphery of a non-magnetic rotating body 2 attached to the output shaft of an engine.
A known three-pole magnet rotor 5 has a magnetic pole piece 3 and a permanent magnet 4 mounted therein, and the magnet 4 is magnetized in the radial direction of the rotating body, and an ignition coil 1 is wound around a U-shaped iron core 6. The armature 7 is fixed to a mounting portion provided on the engine case or the like. An alternating current voltage is induced in the primary coil 1a of the ignition coil 1 in synchronization with the rotation of the engine. The waveform of this voltage with respect to the rotation angle θ is as shown in Figure 5.
The voltage generated in the primary coil 1a during rotation is 1
The positive half-cycle voltage Vp and the two negative half-cycle voltages Vn1 and Vn1 that occur before and after the voltage.
Consists of Vn2.

One end of each of the primary coil 1a and the secondary coil 1b of the ignition coil 1 is commonly connected, and the collector of the transistor 10 is connected to one end of the primary coil 1a. Transistor 10 is a composite transistor in which two transistors are connected in a Darlington manner, and one ends of resistors 11 and 12 are connected to the emitter and base of transistor 10, respectively. The other end of the resistor 11 is the primary coil 1a
The other end of the resistor 12 is connected to the cathode of the diode 13. diode 1
The anode of No. 3 is connected to the primary coil 1a through the resistor 14.
When the primary coil 1a outputs a positive half-cycle voltage Vp, the transistor 10
A base current flows through the transistor 10, making the transistor 10 conductive. In this example, transistor 10, resistors 11, 12, and 14, and diode 1
3 constitutes a transistor switch circuit for controlling the primary current of the ignition coil. The anode of the diode 13 is also connected to the collector of an NPN transistor 15, and the emitter of this transistor is connected to the other end of the primary coil 1a. One end of a resistor 16 is connected to the base of the transistor 15, and the other end of the resistor and the transistor 1
A capacitor 17 is connected between the emitter of 5 and the emitter of 5. A diode 18 is also connected to the other end of the resistor 16.
The cathode of the diode 18 is connected to the anode of the resistor 1 connected to both ends of the primary coil 1a.
It is connected to the voltage dividing point of a voltage dividing circuit consisting of 9 and 20 series circuits. A diode 21 with an anode facing the emitter of the transistor is connected in parallel between the collector and emitter of the transistor 15, and a line to which the anode of the diode 21 is connected is grounded. In this example, a transistor 15, resistors 16, 19, and 20, a capacitor 17, and a diode 18
When the voltage across the primary coil 1a reaches a predetermined value in the positive half cycle of a, the transistor 10
A cut-off control circuit for cutting off a transistor switch circuit consisting of the transistor switch circuit and peripheral parts is constituted, and a primary current control circuit 22 is constituted by this cut-off control circuit and the transistor switch circuit. A secondary coil 1b of the ignition coil 1 is connected to an ignition plug P attached to a cylinder of an engine (not shown).

The above configuration is almost the same as that of a conventional current interrupt type ignition device, but in the present invention, a resistor is connected in series with the emitter of the transistor 10 and the collector-emitter circuit of the primary coil 1a. The voltage across the terminal 11 is used as the voltage for charging the battery 23. In this example, resistor 11
A non-grounded terminal of the diode 24 is connected to the anode of the diode 24, and a battery 23 is connected between the cathode of the diode 24 and the ground. In this example, a battery charging circuit 25 is composed of a resistor 11 and a diode 24.

Further, in this embodiment, one end of a resistor 27 is connected to the positive terminal of the battery 24 through a switch 26, and the other end of the resistor 27 is connected to the positive terminal of the battery 24.
It is connected to the connection point with 3. A load L is connected to the battery 24.

In the above embodiment, when the engine rotates, a voltage is induced in the primary coil 1a as shown in FIG. Positive half cycle voltage Vp across primary coil 1a
When induced, a base current flows through the transistor 10 through the path of primary coil 1a → resistor 14 → diode 13 → resistor 12 → base-emitter of transistor 10 → resistor 11 → primary coil 1a, and transistor 10 becomes conductive. As a result, the primary coil 1
A large primary current flows from a to the collector-emitter of the transistor 10 and through the resistor 11. The resistance value of the resistor 11 is set to a sufficiently small value so as not to limit this primary current too much (so as not to interfere with the ignition operation). The voltage across the primary coil 1a increases as the primary current increases, and when the voltage detected by the resistors 19 and 20 reaches a set value, a predetermined base current flows through the transistor 15. The transistor 15 becomes conductive. This blocks the supply of base current to the transistor 10, so the transistor 10 enters a cut-off state and the primary current is cut off.
At this time, a high voltage is induced in the primary coil 1a in a direction that causes the primary current to continue to flow, and this high voltage is further boosted to induce a high voltage for ignition in the secondary coil 1b. Since this high voltage is applied to the spark plug P, a spark is generated in the spark plug and the engine is ignited. During the negative half-cycle period induced in the primary coil 1a, current flows through the resistor 14, thereby reducing the voltage across the primary coil 1a and applying a high reverse voltage to the transistors 10 and 15. is prevented.

Positive half cycle output voltage of primary coil 1a
When Vp rises and transistor 10 becomes conductive,
A voltage drop occurs across the resistor 11, and this voltage causes a charging current to flow into the battery 23 through the diode 24. In this way, in this example,
Since the battery 23 can be charged every time a positive half-cycle voltage is induced in the primary coil of the ignition coil, the battery can be charged without providing a battery charging coil.

In the embodiment shown in FIG. 1, if the switch 26 is closed when the engine is started, the base current can be supplied from the battery 23 to the transistor 10, so even if an inexpensive transistor with a small hfe is used as the transistor 10, the engine The starting rotation speed (the rotation speed at which the ignition operation starts) can be lowered. In this case, the switch 26 is provided so as to be interlocked with a key switch for starting the engine, and the switch 26 is opened after starting of the engine is completed. In this embodiment, the diode 13 is provided to prevent current from flowing from the battery through the transistor 15 when the transistor 15 is turned on with the switch 12 closed, thereby preventing the battery from being consumed.

In the embodiment shown in Fig. 1, the resistance is 1 when the engine is running at high speed.
If there is a risk of excessive voltage occurring across the battery 23, connect a Zener diode 2 across the battery 23.
8 may be connected to limit the voltage applied across the battery.

FIG. 2 shows a second embodiment of the present invention, in which the transistor 1 of the resistor 11 is
The positive terminal of the battery 23 is connected to the zero side terminal, and the negative terminal of the battery is connected to the anode of a diode 30 whose cathode is connected to one end of the primary coil 1a. Further, the anode of the diode 31 and the cathode of the diode 32 are connected to the other end of the primary coil 1a, and the cathode of the diode 31 and the anode of the diode 32 are connected to the positive and negative electrodes of the battery 23, respectively. Also Batsuteri 2
The negative electrode of No. 3 is grounded. Other points are similar to the embodiment shown in FIG.

In the embodiment shown in FIG. 2, when a voltage is generated across the resistor 11 in the transistor switch circuit due to the output of the positive half cycle of the primary coil 1a, the resistor 1
A charging current flows through the path 1→battery 23→diode 32→resistor 11. Also, when negative half-cycle voltages Vn1 and Vn2 are induced in the primary coil 1a, the primary coil 1a → diode 31 → battery 2
A charging current flows through the path 3→diode 30.
As described above, in this embodiment, the battery is charged by both the voltage across the resistor 11 and the voltage of the negative half cycle of the primary coil 1a, so it is possible to increase the output for charging the battery. can. Further, according to this embodiment, the negative electrode of the battery can be grounded.

FIG. 3 shows a third embodiment of the present invention, in which the battery is charged by the voltage across a resistor 12 connected to the base side of the transistor 10 among the resistors in the transistor switch circuit. . That is, in this embodiment, the resistor 12 is directly connected to the collector of the transistor 15, and the anode of the diode 33 is connected to one end of the resistor 12 on the transistor 15 side. diode 3
The cathode of No. 3 is connected to the positive electrode of the battery 23,
The negative electrode of the battery 23 is grounded. Other points are similar to the embodiment shown in FIG.

In this embodiment, when a negative half-cycle voltage is induced in the primary coil 1a, the voltage changes from the primary coil 1a to the diode 21 to the resistor 12 to the diode junction between the base and collector of the transistor 10 to the primary coil 1a.
A current flows through the path, and the sum of the voltage drop across the resistor 12 and the base-collector voltage drop of the transistor 10 is applied to the battery 23 through the diode 33. Further, the voltage of the negative half cycle of the primary coil 1a is applied to the battery 23 through the diodes 21 and 33, and the battery is charged by these voltages.

In the above embodiment, the transistor 15 is used as a switch element for cutting off the transistor 10.
However, a thyristor may be used instead of the transistor 15.

In each of the above embodiments, the switch 26 and the resistor 27 can be omitted. Figures 1 and 2
In the illustrated embodiment, if switch 26 and resistor 27 are omitted, diode 13 can be omitted.

[Effects of the invention] As described above, according to the invention, the voltage drop that occurs across the resistor in the transistor switch circuit provided for controlling the primary current of the ignition coil is applied to the battery. Therefore, the battery can be charged without installing a battery charging coil inside the magnet generator, and the battery can be charged without changing the specifications of the magnet generator used in small recoil start type internal combustion engines. There are advantages that can be made possible.

[Brief explanation of the drawing]

Figures 1 to 3 are circuit diagrams showing different embodiments of the present invention, Figure 4 is a front view showing a configuration example of a magnet generator used in the present invention, and Figure 5 is a diagram obtained from the same magnet generator. FIG. 3 is a waveform diagram showing voltage waveforms. 1...Ignition coil, 10...Transistor, 1
1, 12...Resistance, 14, 16, 19, 20...
Resistor, 15...Transistor, 23...Battery, 24...Diode, 30-33...Diode.

Claims (1)

[Claims for Utility Model Registration] (1) At least a primary coil is provided in a magnet generator driven by an internal combustion engine, and positive and negative half-cycle voltages are generated in the primary coil in synchronization with the rotation of the engine. A transistor switch circuit in which an ignition coil and a collector-emitter circuit are provided in parallel with the primary coil of the ignition coil, and conductive when a base current is applied with a positive half-cycle voltage induced in the primary coil. and 1 above
An ignition device for an internal combustion engine, comprising a cutoff control circuit that cuts off the transistor switch circuit when the voltage across the primary coil reaches a predetermined level during a positive half cycle of the secondary coil, the transistor switch circuit 1. An ignition device for an internal combustion engine, comprising a battery charging circuit that charges the battery by applying a voltage generated across a resistor provided therein to the battery. (2) The ignition device for an internal combustion engine according to claim 1, wherein the resistor is a resistor inserted in series in the collector-emitter circuit of the transistor switch circuit. (3) The ignition device for an internal combustion engine according to claim 1, wherein the resistor is a resistor inserted in the base circuit of the transistor switch circuit.