JPH0236790B2 - KONDENSAJUHODENSHI KITENKASOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitor charge/discharge type ignition device.

In Patent Application No. 14903 filed in 1981, the ignition timing (angle) is adjusted according to (proportionately) as the engine speed increases within the required set number range, so as to match the output characteristics of the engine. ), and also clarified an inexpensive and economical ignition device that can obtain constant minimum and maximum ignition angle characteristics at rotational speeds below and above the range, respectively. In one embodiment of this ignition device, the maximum ignition angle characteristic is obtained in synchronization with the rise of the positive pulse signal (voltage) of the pulsar coil, and the minimum ignition characteristic is obtained in synchronization with the rise of the negative pulse signal. In other words, the ignition timing is set before the top dead center of the engine, so if the rotation speed is particularly low, such as below the set range, the piston will not be able to pass the top dead center after ignition, and the piston will be pushed back. There were problems such as the so-called butt phenomenon, which was dangerous. In view of the above-mentioned points, the present invention provides an ignition device that can obtain stable ignition characteristics particularly in a low rotation range such as when starting an engine. The present invention will be explained in detail below using the drawings. 1, 2, and 3 are a circuit diagram of an embodiment of the present invention, an operation waveform diagram of each part thereof, and an ignition characteristic diagram, respectively, in which 10 is a generator coil of a magnetic generator or the like rotated by the engine, and 11 is a A rectifier diode 12 is charged via the diode 11 by the voltage generated by the generator coil 10. An ignition power supply capacitor 13 is a thyristor that conducts through a gate circuit to be described later. the ignition coil 1
4, and a spark is generated in the ignition plug 15 via its secondary winding 14-2. Further, the diode 18 is a diode for preventing backflow from the external terminal 21, and the diode 19 is a short-circuiting diode for short-circuiting the output when the output voltage of the generating coil 10 has a polarity opposite to that shown in the figure. It is. The main circuit 1 is configured above. Next, 20 is an ignition signal generating coil (hereinafter referred to as a pulsar coil) that generates a signal voltage at a predetermined ignition angle. Further, ... is a control circuit section of the main circuit section, is a sawtooth wave generating circuit, is a shock wave generating circuit, is a comparator, is a gate circuit, a is a switch circuit, b is a power supply section, and is a power supply section of the present invention. In the retardation circuit that forms the main part, R and C are resistors and capacitors for setting a time constant, and together with a constant voltage diode ZD, they form a frequency (rotation speed) detection circuit. next
Q ₁ and Q ₂ are control transistors, R ₁ and C ₁ are resistors and capacitors forming a differential circuit, and D is a reverse current blocking diode. The control circuit is configured as described above.
Next, the operation will be explained with reference to FIGS. 2 and 3. The above circuits I to V are the same as the previously proposed circuit (Japanese Patent Application No. 56-140903), and their operation is basically that when the engine speed does not reach the set range (N ₁ or less in Fig. 3), the pulsar coil During the period when the signal 20 is positive (Fig. 2 a-), the output voltage of the circuit, that is, the voltage of the capacitor 24 (point E) is set in advance to be higher than the output voltage of the circuit, that is, the voltage of the capacitor 46 (point D). Therefore, the transistor 51 of the comparator circuit is reverse biased and in an off state. Therefore, when a negative signal (Fig. 2 a-) is generated in the pulser coil 20, the transistor 26 of the circuit becomes conductive in synchronization with the rising edge of the signal, and the capacitor 24 is discharged via the transistor 26, and its potential decreases. do. Therefore, when the negative signal arrives, the transistor 51 becomes conductive, and the transistors 61 and 6 of the gate circuit V become conductive.
2 is turned on, capacitor 41 → transistor 6
A gate current flows through the path from 2 to the gate of the thyristor 13, turning on the thyristor 13. Therefore, the comparator circuit outputs in synchronization with the rise of the negative signal set at a predetermined angle of the pulsar coil (Fig. 2 f-
) to the gate, the capacitor 12 discharges and generates a spark at the constant angle minimum ignition timing (θ ₀ ) set by the negative pulse. (Figure 3 a) Also, when the engine speed is within the set range (Figure 3
Figures _N1 and _N2 ) show that as the engine speed increases, the voltage of the capacitor 24 decreases, and in the comparator circuit, the point E voltage becomes lower than the point D voltage earlier, and the transistor 51 becomes conductive earlier. . That is, in the above operation, the transistor 51 becomes conductive at the timing (angle) when the pulsar coil 20 generates a negative signal, but when the set number of circuits _N1 is exceeded, the ignition timing of the thyristor 13 is advanced in proportion to the increase in engine speed. , the ignition timing is advanced early. (Figure 3b)
Furthermore, when the rotation speed _N2 deviates from the set range, the frequency of forming a discharge circuit in the capacitor 24 via the transistor 26 becomes even higher, so that the voltage rise through the resistor 25 becomes more gradual, and the capacitor 24 Voltage (point E) is capacitor 46
The voltage is always lower than the voltage (point D). On the other hand, since the voltage of the capacitor 46 is generated every time a positive signal is generated in the pulsar coil 20 and the transistor 71 is turned on, the voltage in the comparator circuit is determined at the timing synchronized with the rise of the positive signal, that is, at the maximum ignition timing at a certain angle. At θ ₃ , the thyristor 13 becomes conductive and generates a spark.

The present invention further retards the preset minimum angle ignition timing θ ₀ of the pulsar coil at the time of starting, etc., making it possible to ignite the ignition timing near top dead center or at a negative angle beyond top dead center. This is designed to eliminate the butt development at startup. The present invention is characterized in that it has a function of sending out a gate signal in synchronization with the rising timing of the negative pulse of the pulsar coil, and obtains an ignition angle signal that utilizes a delay of the pulse width, compared to the conventional signal synchronized with the rising edge. It is something. The circuit will be explained below.
First, let N ₀ to _{N 1} ' in FIG. 3 be the starting rotation speed. The capacitor 41 of the circuit is a transistor 7 which is made conductive by the positive pulse of the pulser coil 20 (FIG. 2a).
2 and 71, and holds the charge until a discharge circuit is formed by conduction of the transistor 62. Therefore, in the conventional circuit, when the rotation speed is below the set range (N1 _or less in Fig. 3), the transistor 51 becomes conductive at the rising edge of the negative pulse, which causes the transistor 62 to become conductive, so that the capacitor 41
holds the charge for the time indicated by the dotted line in FIG. 2b. On the other hand, the time constant of the resistor R and capacitor C is determined in advance by the time from the rise of the positive pulse to the rise of the negative pulse (second
Figures b-tb) are set shorter. Therefore, the voltage of the capacitor C increases using the capacitor 41 as a power source, and reaches the Zener voltage Vz of the voltage regulator diode ZD before the negative signal pulse rises (Fig. 2C).
Control transistor _Q1 is made conductive. Therefore, the ignition signal applied to the base of the transistor 61 via the transistor 51 at the rising edge of the negative pulse is absorbed into the control transistor _Q1 , and the transistor 61 remains non-conductive. Therefore, the charge on the capacitor 41 is not applied to the thyristor 13 and is maintained even after the time tb, as shown in FIG. 2b. Then, after a time ta, the negative signal of the pulser 20 falls, and when this signal disappears, the transistor 26 turns off.
The voltage on capacitor 24 increases. (Figure 2d)
This voltage is differentiated by the capacitor _C1 and applied to the control transistor _Q2 (FIG. 2e), turning off the transistor _Q1 momentarily via the transistor _Q2 . Therefore, the ignition signal absorbed by the transistor _Q1 flows to the transistor 61, and as a result, the capacitor 41 is discharged through the transistor 62, and a gate signal is given to the thyristor 13. In other words, in Fig. 3, in the conventional example, the ignition signal was always given at the ignition angle θ ₀ up to the rotation speed N ₁ (dotted line a), but in the present invention, the ignition signal was always given at the ignition angle θ 0 at the starting rotation speed (N ₀ to N ₁ '). The ignition angle is retarded by the pulse width fa of the signal, in other words, at an angle closer to top dead center θ ⁰ as shown by line d' in Figure 3, or at an angle -θ beyond top dead center as shown in d. Ignition signal is given (second
Figure f). Next, the engine speed increases, and as a result, the time constant of the resistor R capacitor C becomes the pulse width tb at point E.
If it becomes longer, the voltage of the capacitor C will always be lower than the Zener voltage Vz of the voltage regulator diode ZD.
(Fig. 2C) Therefore, the control transistor _Q1 is always off and does not absorb the ignition signal, but a gate signal is sent out at the rising edge of the negative signal. (FIG. 2f) In other words, between the rotational speeds N ₁ ' and _{N 1} , ignition is performed at the ignition signal angle set at the rising edge of the negative signal as before. In summary, the present invention sends a gate signal at the rise and fall of the negative signal of the pulsar coil, thereby further changing the advance ignition characteristic based on the conventional rise of the negative signal. . In the above embodiments, an example in which the present invention is applied to a previously proposed circuit has been described, but it is obvious that the present invention can also be applied to other ignition devices that use only negative signals. As is clear from the above description, according to the present invention, stable ignition characteristics can be obtained particularly in the low speed rotation range of the engine, and therefore the practical effects are extremely large.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 are circuit diagrams of an embodiment of the present invention, operation waveform diagrams of each part thereof, and characteristic diagrams.
In the figure, the main circuit is a sawtooth wave generation circuit.
is a shock wave generation circuit, is a comparator, is a gate circuit, and is a retard circuit.

Claims (1)

[Claims] 1 A main circuit section that charges a capacitor with the voltage of a generator coil and discharges the charged charge of the capacitor to the ignition coil of the engine via a thyristor in order to generate a spark at the engine's ignition plug; a pulse generating means for generating first and second timing pulses having a preset ignition angle for each cycle; a rising edge of the second timing pulse is defined as a leading edge; and a rising edge of the subsequent second timing pulse is defined as a trailing edge; During this period, a sawtooth wave generation circuit whose peak value continuously rises and changes in accordance with the rotational speed of the engine, and a sawtooth wave generation circuit whose peak value continuously increases and whose peak value changes in accordance with the rotational speed of the engine; a shock wave generating circuit for generating a sharp edge-shaped shock wave having an inclination angle and a peak value that are substantially constant with the leading edge rising portion with the rising edge as the rear end; a comparison circuit for comparing the sawtooth wave and the shock wave; In a capacitor charging/discharging type ignition device equipped with a control circuit that turns on the gate of the thyristor according to the output of the comparison circuit, a charging circuit comprising a capacitor and a resistor that charges in synchronization with the rising edge of the first timing pulse; , a circuit for turning on the gate of the thyristor in synchronization with the falling edge of the second timing pulse only when the charging time constant of the charging circuit is shorter than the rising edge timing of the second timing pulse; A capacitor charge/discharge type ignition device characterized by the following additions.