JPS635596B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitor charging/discharging type ignition device, and in particular, the ignition timing (angle) is adjusted to a nearly constant advance angle when the engine speed is below a predetermined number so as to match the output characteristics of the engine. To provide an inexpensive and economical ignition device capable of obtaining an ignition characteristic of 1, and a substantially constant ignition angle characteristic advanced from the above angle when the rotation speed exceeds the set value. The present invention will be explained in detail below using the drawings. 1st
2, 3, and 4 are a circuit diagram of an embodiment of the present invention, an operation waveform diagram of each part, an operation explanatory diagram, and an ignition characteristic diagram, respectively. In the figure, EXT is a magnet type power generator rotated by the engine. generator coils for machines, etc., D
6 is a rectifier diode, and C is the generator coil.
The ignition power supply capacitor SCR, which is charged via the diode D6 by the voltage generated by EXT, is a thyristor that becomes conductive in response to a trigger signal, which will be described later.This discharges the charge of the capacitor C to the ignition coil gc, A spark is generated at the spark plug SP via the next winding n2. The main circuit is configured above.

Next, the PC is an ignition signal generating coil (hereinafter referred to as a pulsar coil) that generates first and second timing pulses (hereinafter referred to as 1st TP, 2nd TP) with preset maximum and minimum ignition angles for each engine rotation cycle, and the 2nd TP The triangular wave generation circuit generates a triangular wave that rises at a predetermined slope angle in synchronization with the 1st TP and falls in synchronization with the 2nd TP in the next cycle. value, and
The trapezoidal wave generation circuit that generates a falling trapezoidal wave in synchronization with 2TP is a comparator that compares the triangular wave (voltage) and the trapezoidal wave and outputs when the peak value of the trapezoidal wave exceeds the peak value of the triangular wave. , is a gate circuit that triggers the gate of the thyristor SCR by the output of the comparator. The circuit will be explained in detail below.

First, DZ is the pulser coil PC signal voltage (first
Constant voltage element that limits (clamps) 1TP), D
3, C3 is a diode and a capacitor connected between both ends of the pulsar coil PC, and the capacitor C
3 is charged to the clamp voltage by the first TP. C4 is charged with the time constant of resistor R4 using the charging voltage of capacitor C3 as a power source, and rises at a predetermined inclination angle.

Q5 is a resistor R1 across the capacitor C4.
The transistor Q5, which is a transistor connected through 0R12, is turned on by the signal voltage (second TP) to form a discharge circuit for the capacitor C4, so that the capacitor C4 falls in synchronization with the second TP. Note that C5 and R11 are noise absorbing capacitors and resistors of the first TP and second TP, D5 and D7 are rectifying diodes, and the above form a circuit. Next, C1 is a capacitor charged by the first TP via a diode D4, and C2 is a capacitor connected to the capacitor C1 via a resistor R3. Using the capacitor C1 as a power source, the capacitor is charged with a time constant with a resistor R3 to a predetermined level. Stands up at an angle of inclination. ZD2 is a constant voltage diode connected across the capacitor C2, which limits the voltage (peak value) of the capacitor to a constant value. With the above steps, a circuit is formed. Q2
is a transistor forming a comparison circuit, whose emitter is connected to the trapezoidal wave output terminal (point) of the circuit, and whose base is connected to the triangular wave output terminal (point) of the circuit, and whose collector is connected to the comparison output terminal and resistor R5.
connected to the gate circuit via. Next, Q3,
Q4 is a transistor for amplification, and the transistor Q
3 is made conductive by the output of the comparison circuit, thereby making the transistor Q4 conductive. Then, due to the conduction of the transistor Q4, the thyristor
The SCR is mainly supplied with a trigger current from the capacitor C1 and becomes conductive.

Next, FIG. 2 shows the circuit operation of the device of the present invention.
This will be explained with reference to FIG.

First, in Fig. 4, the horizontal axis is the engine rotation speed N,
The vertical axis shows the ignition angle (Θ). The number of revolutions between N0 and N1 is below the set number, and the number of revolutions above N1 is above the set number. When the polarity of the generator coil EXT is on the upper side as shown in Figure 1, the capacitor C becomes the diode D.
6 to the polarity shown. When the polarity of the coil EXT is opposite to that described above, the capacitor C is blocked by the diode D6 and is not charged, and a discharge circuit is not formed for the charge during the first half cycle, and the charging state shown in the figure is maintained. . On the other hand, the signals of the pulsar coil PC (1st TP, 2nd TP) are supplied to the gate of the thyristor SCR via the gate circuit described later when the upper side of the generating coil EXT is on, and in order to turn on the SCR, the capacitor C is charged during this time. The charge is discharged to the ignition coil GC via the thyristor SCR, causing a spark to be generated at the ignition plug SP at a predetermined ignition timing (angle).
Figure 2A shows the signal voltage waveform, which shows the positive signal voltage (1st TP) at the maximum (angle) advanced position from the engine's top end point (not shown), and the negative signal voltage (2nd TP) at the minimum advanced position. ), and the corresponding number
The 1TP and 2nd TP signals are generated once per revolution of the engine (flywheel). Note that ' and ' indicate the first TP and second TP in the next cycle.
Therefore, when the first TP in FIG. 2A occurs, the signal voltage is rectified via the diode D5, and is made into a constant voltage by the constant voltage element DZ1 and applied to the circuit. That is, first, capacitor C3 is charged to the constant voltage VZ through diode D3. (Fig. 2B) Next, the capacitor C4 of the circuit is charged with the time constant of the resistor R4 using the capacitor C3 as a power source, and rises at a predetermined slope angle, and when the second TP arrives, a discharge circuit is formed via the transistor Q5. For,
A triangular wave falling in synchronization with the second TP is formed.
(Fig. 2 E) Also, the capacitor C1 of the circuit is
It is charged to the constant voltage through the diode D4 in synchronization with 1TP, and a discharge circuit is formed by the trigger of the thyristor SCR, which will be described later. (Fig. 2C) On the other hand, capacitor C2 is charged with the time constant of resistor R3 using capacitor C1 as a power source (that is, in synchronization with the first TP), so it rises at the required slope angle, and its peak value is the voltage regulator diode. When the voltage of DZ2 reaches VZ2, it is limited to this voltage, and a discharge circuit is formed by conduction of a transistor Q2 of a comparison circuit, which will be described later, to form a falling trapezoidal wave. (FIG. 2D) Next, the operation of the comparator circuit and the gate circuit will be explained with reference to FIG. 3. In Fig. 3, the triangular wave 0 and the trapezoidal wave are enlarged views of the voltage waveforms of capacitors C4 and C2, respectively, when the engine speed is N1, and ΘM is the maximum advance angle (1st TP),
Θm is the minimum advance angle (second TP) and θ0 is the set advance angle. The transistor Q2 of the comparator circuit has its base connected to the point shown in FIG. 1, and its emitter connected to the point shown in FIG. 1, and is made conductive by being biased over time so that the potential at the point is higher than the potential at the point. Therefore, when the set engine speed (N1) is set to 4000 rpm, for example,
The period between 2TP and 2TP' in the next cycle is T2, and the period between 1TP' and 2TP' in the next cycle is T1, and the output voltage of the triangular wave (capacitor C4) in this period T2 is shown in Figure 3 as e0. Then, if the time constant with the resistor R4 is set so that its peak value becomes The discharge timing through the transistor Q5 is delayed, and during this time the capacitor C4 is charged, so its output voltage is at a high level as shown in e2 and e1 in FIG. On the other hand, the voltage of the trapezoidal wave (capacitor C2) in the set rotation period T1 reaches the voltage VZ2 of the voltage regulator diode at the required time of the period T1 (Fig. 3).
When the time constant between the triangular wave 0 and the trapezoidal wave is set, the transistor Q2 becomes conductive near the intersection of the triangular wave 0 and the trapezoidal wave, turning on the transistors Q3 and Q4 of the gate circuit V. Therefore, a trigger current due to the discharge of the capacitor flows through the path of the capacitor C1→transistor Q4→thyristor SCR and makes the thyristor SCR conductive. In other words, the trapezoidal wave is generated by the 1st TP (ΘM) and the 1st TP (ΘM) of the maximum and minimum advance angles set in advance by the pulser coil PC.
Since it is formed between 2TP (Θm), the capacitor C discharges at the above-mentioned intersection point, that is, the angle (Θ0), and generates a spark. (FIG. 4A) Next, when the number of revolutions does not reach the set number (N1), the triangular wave outputs e1 and e2 are higher than the trapezoidal wave in the period T1, as described above. Therefore, the triangular wave (capacitor C
The output voltage e1e2 of 4) becomes conductive due to the arrival of the second TP, and a discharge circuit is formed.
At the point when the potential drops, it becomes lower than the trapezoidal wave.
That is, the potential at the point in FIG. 1 becomes lower than the potential at the point, and the transistor Q2 becomes conductive. In other words, the 2nd TP with the minimum advance angle
Since the ignition signal is generated in synchronization with the ignition signal, it is possible to obtain the characteristic of ignition at the angle Θm shown in FIG. 4B. On the other hand, when the rotation speed is higher than the set number (N1), the third
As shown in the figure, the period T2 changes to T2' and T1 changes to T1'. Note that the trapezoidal wave in the period T1 reaches the set voltage VZ2 at the end of the period in the period T1', so it can be regarded as a triangular wave ''''. Therefore, the relationship between the two can be explained by comparing the apparent triangular wave at period T1. That is, the ratio of both changes, ie (T1/T2) and (T1'/T
2′) is constant. Therefore, the intersection point between the triangular wave 0'' and the triangular wave ``'' is located at the same ratio as the above-mentioned intersection point between the first TP and the second TP. In other words, the advance angle remains the same regardless of the change in rotational speed. (4th
Figure A) According to the present invention, when the triangular wave voltage is always higher than the set voltage VZ2 (during low speed rotation), the trapezoidal wave voltage, that is, the voltage setting of the constant voltage diode DZ2, according to the present invention, the minimum advance is synchronized with the arrival of the second TP. Obtains a constant advance characteristic of the angular angle (Θm), and obtains a so-called two-stage (step-like) advance characteristic of a constant angle advanced from the above angle when the rotation speed reaches the set voltage or higher. be able to. This step width, that is, the advance angle width from the minimum advance angle (Θm) can be increased to the maximum advance angle position (ΘM) as shown in FIG. ).As is clear from the above explanation, according to the present invention, when the engine speed is below the set number, a certain minimum advance ignition characteristic is obtained, and when the engine speed is above the set number, a certain minimum advance ignition characteristic is obtained. Since a constant advance ignition characteristic that is more advanced than this can be obtained with a simple construction and at low cost, the practical effect is extremely large.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams of an embodiment of the present invention and operation waveform diagrams of each part thereof, FIG. 3 is an explanatory diagram of the operation of the present invention, and FIG. 4 is a characteristic diagram of the present invention. In the figure, the main circuit, is a triangular wave generation circuit, is a trapezoidal wave generation circuit, is a comparison circuit, is a gate circuit, C, C
1, C2, C3 and C4 are capacitors, SCR is a thyristor, D1, D2, D3, D4, D5, D
6 and D7 are diodes, gt is an ignition coil, DZ1, DZ2 are constant voltage elements, Q2, Q
3, Q4 and Q5 are transistors, R3 and R4 are resistors, and PC is a pulse generating coil (circuit).

Claims (1)

[Scope of Claims] 1. (a) A main circuit that charges a capacitor with the voltage of the generator coil and discharges the charge of the capacitor to the ignition coil via a thyristor that conducts in response to a trigger signal; (b) a pulse generation circuit that generates first and second timing pulses with preset maximum and minimum ignition angles for each engine rotation cycle; (d) a triangular wave generating circuit that generates a triangular wave that falls in synchronization with a second timing pulse at a time; and a trapezoidal wave generation circuit that generates a trapezoidal wave that falls in synchronization with the second timing pulse; A capacitor charging/discharging type ignition device comprising: a comparison circuit that outputs an output; and (f) a gate circuit that triggers the thyristor based on the output of the comparison circuit.