JPH029099Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an engine ignition timing control device that uses a magnet generator as a power source.The purpose of this invention is to advance the ignition timing based on the waveform growth of the signal voltage until the engine reaches the set rotation speed. When the set rotation speed is reached, the ignition timing is retarded, and the power supply voltage of the monostable circuit that makes up the retard circuit is a constant voltage powered by the AC output generated in the signal coil of the magnet generator. By forming the retard circuit by a circuit, the retard circuit can be constructed easily and inexpensively, and can also be applied to an engine not equipped with a DC power source such as a battery.

The following description will be made with reference to the embodiment shown in FIG. 1. In the figure, 1 is a magnet generator rotationally driven by an engine, and has a generator coil 2 for ignition and a signal coil 3 for determining the ignition timing. However, each coil 2, 3 generates an AC output voltage synchronized with engine rotation. Also,
The generator coil 2 is configured to generate a high-voltage AC output, and the signal coil 3 has an angular width larger than the ignition timing control width ranging from the maximum retard position to the maximum advance position, and is configured to generate an AC output at a lower voltage than the output voltage of. 4 is a capacitor that is charged by the rectified voltage in direction a of the generator coil 2; 5 is an ignition coil that induces an ignition voltage by releasing the charge from the capacitor 4; and 6 is a thyristor that releases the charge from the capacitor 4 to the ignition coil 5. , the gate is connected to the signal coil 3 via a transistor 7, a resistor 8, and a diode 9.
It is connected to one end A of , and is also grounded via a gate resistor 10 . 11 is a diode connected to one end A of the signal coil 3; 12 is the signal coil 3;
A diode 13 connected to the other end B is a retard circuit that retards the ignition timing, and is configured as follows. That is, 14 is a constant voltage circuit that forms a constant voltage (Vcc) based on the b-direction voltage B of the signal coil 3;
It is composed of a diode 15, a resistor 16, a capacitor 17, and a constant voltage diode 18. 19 is a signal forming circuit that forms an angle signal at a predetermined crank position of the engine based on the b-direction voltage B of the signal coil 3, and includes a diode 20, a resistor 21, and a capacitor 22.
Consisted of. 23 is a monostable circuit that receives the angle signal C based on the constant voltage (Vcc) of the constant voltage circuit 19 and generates a pulse voltage D for a fixed time, and is composed of NOR gates 24 and 25, a resistor 26, and a capacitor 27. 28 is a control circuit that can feed or cut off the a-direction voltage A of the signal coil 3, which is fed to the gate of the thyristor 6, based on the pulse voltage D;
It is composed of a resistor 29 and a transistor 7.

The operation of the embodiment configured as described above will be explained using the operation waveform diagram shown in FIG. In Fig. 2, M is the conduction position of the thyristor 6, (TDC) is the top dead center of the engine, A is the voltage waveform in the a direction of the signal coil 3, and B
is the b-direction voltage waveform of the signal coil 3, and the b-direction voltage B is set to occur at a position that is ahead of the a-direction voltage A by a crank angle α. C is the angle signal waveform generated in the signal forming circuit 19, D is the pulse voltage waveform of constant time T generated in the monostable circuit 23, E is the gate voltage waveform of the thyristor 6, (V _g )
is the trigger level of the thyristor 6.

The engine shall require the ignition timing characteristics shown in Figure 3.

First, in synchronization with the rotation of the engine, the signal coil 3 receives alternating current voltages A and B in directions a and b shown in FIGS. 2A and B.
B is generated, and the a-direction voltage A is rectified by the diode 9 and applied to the gate of the thyristor 6 via the resistor 8 and the transistor 7. This a-direction voltage A is a when the output of the monostable circuit 23 is LOW.
The directional voltage becomes the base current of the transistor 7, makes the transistor 7 conductive, and power is supplied to the gate of the thyristor 6. Also, b direction voltage B
is applied to the constant voltage circuit 14 and the signal forming circuit 19, respectively, and the constant voltage circuit 14 stabilizes the b-direction voltage B including the pulsating current component to the constant voltage (Vcc) of the constant voltage diode 18, and the signal forming circuit 19 b
An angle signal C is generated near the maximum value of the directional voltage B, that is, at a predetermined crank position of the engine. This is because the electric charge of the capacitor 22 charged with the first b-direction voltage B is gradually discharged via the resistor 21, and the next b-direction voltage B is applied while this electric charge remains.
This is because the differential voltage will be generated on the output side of the capacitor 22 only when a voltage exceeding the residual charge is supplied. Now, when the monostable circuit 23 is in a stable state, when the angle signal C is input to the NOR gate 24, the monostable circuit 23 becomes in an unstable state.
Since the input of the NOR gate 24 instantaneously becomes HIGH and its output is inverted to LOW, the capacitor 27 is charged to the illustrated polarity through the resistor 26 based on a constant voltage (Vcc). As a result, each input of the NOR gate 25 is inverted to LOW, and its output is inverted to HIGH. Therefore, when the terminal voltage of the capacitor 27 rises to about 1/2 of the constant voltage (Vcc), the input of the NOR gate 25 is reversed from LOW to HIGH.
The output of the NOR gate 25 is inverted from HIGH to LOW, and the monostable circuit 23 becomes stable again. That is, the monostable circuit 23 receives the angle signal C generated at a predetermined crank position of the engine as shown in FIG. A pulse voltage D is generated having the following value. The pulse width T of this pulse voltage D remains constant regardless of an increase or decrease in the engine speed. (However, the pulse angle that is tightened during one rotation of the engine changes.) Then, the transistor 7 of the control circuit 28 cuts off only the period during which the pulse voltage D is generated, cuts off the a-direction voltage A of the signal coil 3, and passes the voltage to the gate of the thyristor 6. block the power supply. on the other hand,
A and b direction voltages A and B generated in the signal coil 3
As shown in FIGS. 2A and 2B, the generation period becomes shorter as the engine speed increases, and the peak values of the voltages A and B in the a and b directions grow in waveform as the engine speed increases.

Now, in the rotation range until the engine speed increases to N ₁ , the thyristor 6 is connected to the a of the signal coil 3.
The control circuit 28 supplies the directional voltage A to the gate of the thyristor 6 without being cut off, and conducts at the position where the a-directional voltage A reaches the trigger level (V _g ) of the thyristor 6, and the charge on the capacitor 4 becomes The ignition coil 5 is made to emit it. The conduction position of this thyristor 6, that is, the ignition timing of the engine, is determined by the waveform growth of the a-direction voltage A of the signal coil 3 as the rotation speed increases, and the position at which it reaches the trigger level (V _g ) is on the side of the predetermined crank position of the engine (advanced). The angle is advanced as shown in FIG. 3 by being advanced in the angular direction). Here, as the rotational speed of the engine increases, the generation period of the a and b direction voltages A and B of the signal coil 3 becomes shorter, and the generation period of the pulse voltage D of the monostable circuit 23 is a fixed time T, so that The a-direction voltage A of the signal coil 3, that is, the second
The gate voltage E of the thyristor 6 shown in Figure E is cut off by the transistor 7 (dotted line waveform in Figure 2 E), and since the cut-off period is a constant time with respect to the rotation speed, the cut-off angle is proportional to the increase in the rotation speed. and grow bigger.

Therefore, when the engine increases to the set rotation speed _N1 , the timing when the gate voltage E reaches the trigger level (V _g ) and the pulse voltage D of the monostable circuit 23 changes from HIGH to
The timing at which the transistor 7 becomes conductive due to the inversion to LOW coincides, and therefore the thyristor 6 becomes conductive at this coincident timing.

Furthermore, in the rotation range in which the engine speed exceeds the set rotation speed _N1 , the angle at which the gate voltage E of the thyristor 6 is cut off by the transistor 7 increases,
Therefore, when the transistor 7 is turned on, the gate voltage E is applied to the thyristor 6, and the thyristor 6 is turned on. The conduction timing of the thyristor 6, that is, the ignition timing, is retarded as shown in FIG. 3B, as the conduction timing of the transistor 7 approaches the top dead center (TDC) proportionally as the rotational speed increases.

As mentioned above, until the set rotation speed N ₁ is reached, the waveform advance angle characteristic A is obtained, and when the rotation speed rises above the set rotation speed N ₁ , the electrical retard angle characteristic B is obtained.
In the case of a 4-cycle engine, over-rotation can be prevented, and in the case of a 2-cycle engine, the torque can be improved at high rotations, so that the engine can be driven suitably. Furthermore, the set rotational speed _N1 can be arbitrarily set by adjusting the time constant of the resistor 26 and capacitor 27 of the monostable circuit 23, or by changing the generation timing of the angle signal C.

Although a single signal coil 3 is used in the above, two signal coils 3a and 3b are used as shown in FIG.
may be formed, and the b-direction voltage B may be formed by the other signal coil 3b.

Although the constant voltage circuit 14 uses the b-direction voltage B of the signal coil 3, the same effect can be obtained by using the a-direction voltage A of the signal coil 3, as shown in FIG.

This is because this type of engine is normally not equipped with a battery (even if a battery is installed, the capacity is small and the power supply voltage fluctuates widely, so it cannot be applied to this example), but this device is not applicable to this example. By using the voltage circuit 14, it is fully applicable to such an engine. That is, since the constant voltage circuit 14 generates the constant voltage (Vcc) of the monostable circuit 23 from the output voltage of the signal coil 3, which is not necessary for this device, there is no need to provide a new generator, and the electric circuit can be constructed easily and inexpensively. Furthermore, it has the characteristic of obtaining sufficient ignition timing characteristics. Here, it is possible to form a constant voltage (Vcc) from the generator coil 2, but in such a system, the high voltage generated in the generator coil 2 for the ignition power source is converted to a low voltage for the monostable circuit 23 power source. This requires a voltage conversion means and a large capacitor, making the configuration complicated and expensive. Furthermore, when obtaining a constant voltage (Vcc) from the generator coil 2, it is difficult to obtain a stable voltage (Vcc) due to severe load fluctuations on the generator coil 2.
3 has a fatal drawback that it may cause malfunction.

As described above, according to this invention, the ignition timing is advanced based on the waveform growth of the signal voltage generated in the signal coil of the magnet generator until the engine reaches the set rotation speed, and is retarded once the engine reaches the set rotation speed. The constant voltage of the monostable circuit constituting the retard circuit is formed by a constant voltage circuit from the voltage of the signal coil, and the monostable circuit is triggered to generate a pulse signal having a pulse width of a certain time. The angle signal for this purpose is formed by a signal forming circuit from the signal voltage of the signal coil, and the retarding circuit can be constructed easily and inexpensively, and it also has significant practical effects such as being applicable to engines that are not equipped with a DC power source such as a battery. Demonstrate.

[Brief explanation of the drawing]

Figure 1 is an electric circuit diagram showing one embodiment of this invention, Figure 2 is an operating waveform diagram of the circuit in Figure 1, Figure 3 is an ignition timing characteristic diagram obtained from the circuit in Figure 1, and Figure 4 is an ignition timing characteristic diagram obtained from the circuit in Figure 1.
FIG. 5 is an electrical circuit diagram showing another embodiment of this invention. In the figure, 1 is a magnet generator, 2 is a generator coil,
3, 3a, 3b are signal coils, 6 is a thyristor,
13 is a retardation circuit, 14 is a constant voltage circuit, 19 is a signal forming circuit, 23 is a monostable circuit, and 26 is a control circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] A relatively low voltage generator that is attached to a magnet generator rotationally driven by the engine, is synchronized with the rotation of the engine, and has an angular width larger than the ignition timing control width from the maximum retard position to the maximum advance position. A signal coil that generates AC output is attached to the above magnet generator,
A generator coil that generates a high-voltage AC output in synchronization with the rotation of the engine; an ignition circuit that uses the AC output of the generator coil as a power source and uses the unidirectional output of the AC output of the signal coil as an ignition signal; a constant voltage circuit that has a capacitor charged by AC output and a constant voltage element and forms a constant voltage power supply;
A signal forming circuit that receives the alternating current output of the signal coil and forms an angle signal at a predetermined crank position of the engine; the output voltage of the voltage circuit is used as a power source, and a pulse having a pulse width of a certain time from the position where the angle signal is generated; A monostable circuit that generates a signal, and a control circuit that blocks the supply of the ignition signal to the ignition circuit during the generation period of the pulse signal. An engine ignition timing control device characterized in that the ignition timing is retarded by supplying an ignition signal based on the signal.