JPH0338456Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an ignition advance device for a small internal combustion engine.

[Prior art]

Conventionally, advance angle control for this type of ignition system uses angle calculation for systems that require high precision, so-called electronic advance control, and for systems that require low cost, the ignition timing is controlled in stages at a constant rotational speed of the internal combustion engine. A jump advance method was used, which advanced the angle in a straight line.

Conventional jump advance angle devices utilize the fact that the output voltage of the signal generator coil provided in the magnet generator increases as the rotation speed increases, and are configured to advance when the voltage reaches a certain value. Therefore, the advance angle rotation speed depends on the voltage of the signal generator coil, and the voltage of the signal generator coil is greatly affected by the air gap, magnet characteristics, temperature, etc., and the generated voltage changes widely, so the advance The accuracy of the angular rotational speed itself is extremely poor, and currently it is hardly used in anything other than some internal combustion engines.

[Summary of the idea]

This invention was made to eliminate the drawbacks of the conventional ones as described above.In order to improve the accuracy of the jump advance angle method, advance angle rotation can be performed using a simple electronic circuit without depending on the voltage of the signal generator. The purpose of the present invention is to provide an internal combustion engine ignition device that allows the number of settings to be made, and that improves accuracy without sacrificing its low cost.

[Example of idea]

An embodiment of this invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of an embodiment of the present invention, and FIG. 2 is a concrete example thereof. In the figure, reference numeral 1 denotes a generator coil for ignition power supply of a magnet generator, and the output of the generator coil 1 is rectified by a diode 2 and then charges a capacitor 3. A thyristor 4 receives a signal at the gate at the ignition timing of the internal combustion engine, becomes conductive, releases the charge in the capacitor 3 to the primary coil 6 of the ignition coil 5, generates a high voltage in the secondary coil 7, and fires the spark plug. 8 and ignites the internal combustion engine.
9 is a signal source, which in this embodiment is a signal coil, generates a signal in synchronization with the internal combustion engine, and its output is full-wave rectified by diodes 10, 11, 12, and 13, one being a delayed signal 9a and the other is applied to the gate of the thyristor 4 as a lead signal 9b. 14 and 15 are impedance elements inserted in the signal circuit, and in the case of FIGS. 1 and 2, the impedance element 14 on the advance signal 9b side indicates that the advance signal 9b strikes the thyristor 4 when the revolution speed of the internal combustion engine is below a certain number. The value is selected so large that it will not be driven. Note that the delay signal 9a is set to adapt to the ignition timing when the internal combustion engine is running at low speed, and the advance signal 9b is set to adapt to the ignition timing when the internal combustion engine is running at high speed. 16 is a power supply circuit, as shown in FIG.
7, 18, resistor 19, 20, 21, capacitor 2
2, and a Zener diode 23, receives power from the generator coil 1, and generates a constant voltage.
It is configured to output Vcc. 24 is a constant time setting circuit, which includes transistors 25, 26,
27, resistors 28, 29, 30, 31, 32, capacitors 33, 34, and a diode 35. 36 is a switching element, and in this embodiment a transistor is used.
In the case shown, the transistor 36 is configured to bypass the lead signal 9b of the signal coil 9.

Next, the operation shown in FIG. 2 will be explained based on FIGS. 3 and 4.

The signal coil 9 generates a lead signal 9b and a delay signal 9a, as shown in FIG. 3S. The delayed signal 9a of these two signals is applied to the base of the transistor 25 of the fixed time setting circuit 24 to turn on the transistor 25. When the transistor 25 is turned on, the power supply circuit 16 causes the transistor 25 to be turned on.
via capacitor 33 and transistor 26
Current flows to the base of the capacitor 33, and the capacitor 33 is charged. The charging time of the capacitor is determined by the time constant of the current circuit.
6 turns on. Therefore, the emitter voltage of the transistor 26 is given a pulse voltage of a constant width, as shown in FIG.
The capacitor 34 is charged to the power supply voltage via the capacitor 34 . If the transistor 26 turns off after a certain period of time,
The charge in the capacitor 34 is discharged through the resistor 31 as shown in FIG. 3B.

The above operation is repeated every time a signal is applied to the base of the transistor 25.
After a signal is input to the capacitor 34, the voltage of the capacitor 34 turns off the transistor 27 and the capacitor 34 is turned off.
discharges and drops to a constant voltage, transistor 2
7 turns on. Since charging and discharging of the capacitor 34 depend on a time constant determined by a circuit constant, the time from when a signal is input to the transistor 25 until the transistor 27 is turned on is always constant. When the transistor 27 is turned on, voltage is applied from the power supply circuit 16 to the base of the transistor 36, and the transistor 36 is turned on, thereby bypassing the lead signal 9b of the signal coil 9. Therefore, as shown in FIG. 3C, the transistor 36 is turned off by the delayed signal 9a of the signal coil 9, and turned on after a certain period of time.

While the rotational speed of the internal combustion engine is low, transistor 3
6 is turned on when the internal combustion engine rotates to a certain extent, so the advance signal 9b is bypassed (in the region n<n ₂ in FIG. 3). As the rotational speed of the internal combustion engine increases, the rotation angle increases during the certain period of time, and when a certain rotational speed _n2 is reached, the ON position of the transistor 36 advances as shown in the n> _n2 region in FIG. The signal 9b is angularly delayed from the position where the signal 9b is generated, and the delayed signal 9a is applied to the gate of the thyristor 4.
and advance signal 9b are added. Since the discharge of the capacitor 3 is performed using the advance signal _9b which is earlier in time, as shown in _{FIG .} The ignition position is advanced in stages. This advance angle rotation speed _n2 is determined by the selection of the time constant of the fixed time setting circuit, and variations in components can be corrected by adjusting the resistance value of the discharge circuit, for example.Moreover, the signal voltage value of the signal coil 9 Since they are completely unrelated, extremely high accuracy can be achieved.

In another embodiment shown in FIG. 5, when the voltage of the capacitor 34 is above a certain value, the transistor 27a is turned on, and the transistor 36 connected in series with the lead signal circuit is turned on. When the on-period is angularly short, the advance signal 9b is blocked, and at a constant rotation _n2 or more, the on-angle advances and covers the signal 9b, giving the signal to the thyristor 4, and the effect is the second. This is exactly the same as the embodiment shown in the figure, and in the case of FIG. 5, the impedance element 14a may simply be set as a current limiter. Furthermore, in the case of FIG. 5, it is sufficient to consider that the on/off state in FIG. 3C is reversed.

[Effect of idea]

As described above, according to the present invention, it is possible to provide a small and excellent internal combustion engine ignition system that can obtain extremely high-precision jump advance angle by simply adding a simple power supply circuit and a fixed time setting circuit.

In addition, it consists of a CR time constant circuit that performs charging and discharging by controlling the switching transistor with a delayed signal, and an output transistor that operates in response to the capacitor voltage resulting from the charging and discharging. is the output of the constant time setting circuit obtained from the same power supply line,
Since the switching circuit is closed and the advance signal is bypassed, the accuracy does not change even when the power supply voltage fluctuates, and operation is more stable than in the low speed range, resulting in stable ignition timing and operating rotation. This has the advantage of providing an internal combustion engine ignition system with improved performance.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of an internal combustion engine ignition system according to an embodiment of the present invention, Fig. 2 is a circuit diagram of a specific example thereof, and Fig. 3 is a conceptual diagram of an internal combustion engine ignition system according to an embodiment of the present invention.
4 and 4 are operation explanatory diagrams, and FIG. 5 is a circuit diagram of another embodiment. 1...Generating coil, 2...Diode, 3...
Capacitor, 4... Thyristor, 5... Ignition coil, 6... Primary coil, 7... Secondary coil, 8...
...Spark plug, 9...Signal source (signal coil), 9
a...delay signal, 9b...advanced signal, 16...power supply circuit, 24...fixed time setting circuit, 36...switching element (transistor). In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims for Utility Model Registration] (1) A generator coil that generates power for ignition of an internal combustion engine, a diode that rectifies the output of the generator coil, a power supply circuit that operates with the output, and a power supply circuit that is rectified by the diode. The capacitor charged by the output of the generator coil is electrically connected to the capacitor charged by the output of the generator coil at the ignition timing of the internal combustion engine by a signal from the signal source described below, and the charge in the capacitor is discharged to the primary side of the ignition coil of the internal combustion engine, a thyristor that generates a high voltage on the secondary side of an ignition coil to ignite the internal combustion engine; a delay signal that adapts to the ignition timing when the internal combustion engine rotates at low speed; and an advance signal that adapts to the ignition timing when the internal combustion engine rotates at high speed. a signal source that generates a signal and gives a signal to the gate of the thyristor at the ignition timing of the internal combustion engine, a CR time constant circuit that charges and discharges by controlling the switching transistor with the delayed signal, and a capacitor that uses the charging and discharging. It consists of an output transistor that operates in response to voltage, and a constant time setting circuit that obtains the capacitor charging voltage and the collector voltage of the output transistor from the same power supply line and outputs the voltage for a certain period of time, and is controlled by the output of this fixed time setting circuit. and a switching circuit that closes to invalidate the advance signal when the rotational speed of the internal combustion engine is below a certain value. (2) The switching circuit is configured to be able to bypass the advance signal, and is configured such that the switching element of the switching circuit becomes non-conductive at a predetermined rotational speed or higher of the internal combustion engine by the output of the fixed time setting circuit, and The output of the signal circuit is the rotational speed at which the rotational speed of the internal combustion engine has increased to a certain degree.
A voltage capable of driving the thyristor is obtained at n ₁ , and the rotation speed n ₁ is higher than the operation start rotation speed n ₀ of the fixed time setting circuit, and the rotation speed n that requires advance of the internal combustion engine is set. The first claim for utility model registration characterized by setting the value lower than ₂ .
Internal combustion engine ignition system as described in . (3) The advance signal is configured to be applied to the gate of the thyristor via a switching element of the switching circuit, and when the internal combustion engine exceeds a predetermined rotation speed, the switching element is made conductive by the output of the fixed time setting circuit. An internal combustion engine ignition system according to claim 1, characterized in that the internal combustion engine ignition system comprises: