JPS5938433B2 - engine ignition system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine ignition system, and particularly to control of engine ignition timing.

Conventionally, in this type of engine ignition system, an ignition voltage is generated on the secondary side by controlling the primary current of the ignition coil by operating a switching element such as a thyristor or transistor using an ignition signal generated at the ignition timing of the engine. There is.

However, in this case, the signal voltage generated in synchronization with the engine rotation is directly supplied to the switching element as an ignition signal, so 1. The advance characteristic of the ignition timing is determined by the output waveform of the ignition signal, which has the disadvantage that it cannot meet the advance characteristic originally required for an internal combustion engine.

In view of the above-mentioned drawbacks, this invention arbitrarily controls the ignition timing characteristics of the engine to satisfy the advance characteristics required by the engine.In particular, when the engine is running at high speeds, the ignition timing is delayed to reduce the engine output due to abnormal combustion. To provide an engine ignition device that prevents engine ignition from decreasing and improves engine output over a wide range from low to high engine speeds.

The embodiment shown in FIG. 1 will be described below.

In FIG. 1, reference numeral 1 denotes a power generation coil that is built in an AC magnet generator driven by an engine (not shown) and generates an AC output voltage in synchronization with the rotational speed of the engine, and reference numeral 2 designates this power generation coil 1.
3 is a capacitor charged by this rectified output, 4 is an ignition coil, 5 is a diode that rectifies the AC output of
6 is an ignition plug, and 6 is a thyristor which is an opening/closing element, and discharges the charge charged in the capacitor 3 to the primary coil of the ignition coil 40 (constituting a discharge circuit).

14 is a signal shaping circuit that constitutes the main part of the present invention; 7 is a signal generator that is driven by the engine and generates an AC output voltage whose value increases or decreases as the engine speed increases; 8 is a signal generator of the signal generator 7; This is a diode that allows the output of the polarity (direction a in FIG. 1) that provides an ignition signal to the gate of the thyristor 6 to pass among the AC outputs.

The AC output of the signal generator 7 is configured to be supplied to the gate of the thyristor 6 via a diode 8 and a resistor 9.

12 is a transistor connected in parallel to the resistor 9 via a capacitor 10; 11 is a diode connected in parallel to the transistor 12; the capacitor 10 and the resistor 9 constitute a discharge circuit.

13 is a Zener diode which is a voltage detection element connected to the base of the transistor 120, and the output of the signal generator 7 (
When the current (direction a in FIG. 1) reaches a predetermined value, a base current is supplied to the transistor 12.

Next, the operation of the device configured as described above will be explained with reference to the operational waveform diagram in FIG. 2 and the characteristic curve diagram in FIG. 3.

First, the alternating current output generated in the generator coil 1 of the magnet generator by the rotation of the engine is rectified by the diode 2 and charges the capacitor 3.

Therefore, when the ignition timing of the engine comes, the ignition signal voltage generated in the signal generator 7 is rectified by the diode 8 and supplied to the gate of the thyristor 6 via the resistor 9.

As a result, the thyristor 6 becomes conductive and the charge in the capacitor 3 is discharged to the primary coil of the ignition coil 40, so that an ignition voltage is generated in the secondary coil, and in response to this ignition voltage, a spark discharge occurs in the ignition plug 5. It will be done.

Next, the manner in which the ignition signal is applied to the gate of the thyristor 6 will be described in detail using the waveform diagram shown in FIG.

A in FIG. 2 is the AC output voltage V of the signal generator 7 in the a direction.

In the figure, nl j n2
j n3 j n4 (n□<n2<n3< n
4) indicates the engine speed.

Now, when the engine speed n increases from nl to n2, the AC output of the signal generator 7 increases accordingly, and when the voltage that makes the thyristor 6 conductive (Vg in Figure 2 A) is reached, the thyristor 6 becomes conductive. Ignition voltage is generated.

Therefore, the ignition timing of the engine is gradually advanced from tl to t2 (X in Figure 3).

Next, when the engine speed further increases to n3 and the output voltage of the signal generator 7 exceeds the zener voltage Vz of the zener diode 13, the base current is supplied to the transistor 12 via the zener diode 13. .

As a result, the transistor 12 becomes conductive, and the positive half wave (direction a in FIG. 1) of the AC output of the signal generator 7 charges the capacitor 10 to the polarity shown in FIG. 1 via the diode 8 and the transistor 12.

This charged charge is discharged via the diode 11 and the resistor 9 with a time constant determined by the capacitor 10 and the resistor 9.

This shows the charging voltage Vc of the singing capacitor 10 in FIG. 2.

Now, when the engine speed n reaches n3, the voltage Vc of the capacitor 10 is charged to the value of vc3 (Figure 2), so the output voltage of the signal generator 7 exceeds Vc3 at the time t3.
At this point, the ignition signal is applied to the gate of the thyristor 6, so that the ignition timing of the engine becomes t3.

Furthermore, when the engine speed n increases to n4, the output of the signal generator 7 also increases, and the charging voltage of the capacitor 10 also increases.

At the time of generation of the next ignition signal, the voltage across the capacitor 10 is V.
c4, and at time t4 when the output of the signal generator 7 exceeds Vc4, an ignition signal is applied to the gate of the thyristor 6, and the thyristor 6 becomes conductive.

That is, when the engine speed n increases from n3 to n4, the ignition timing of the engine is retarded from t3 to t4 (Y in FIG. 3).

Furthermore, the engine speed increases, the output of the signal generator increases, the charging voltage of the capacitor 10 also increases, and the voltage Vc of the capacitor 10 when the next ignition signal is generated also increases, so the ignition retard ends, and finally the ignition timing becomes almost constant.

(Fig. 3 2) Fig. 3 compares the ignition timing advance characteristic θ with respect to engine speed n between this embodiment device and a conventional device. ■
shows the characteristics obtained by this example.

As described above, by providing the signal shaping circuit 14, it is possible to retard the engine during high speed rotation, and the capacitance of the capacitor 10,
Value of resistor 9, output voltage characteristics with signal generator 70 rotation speed,
By appropriately changing the zener voltage of the zener diode 13, it is possible to change the advance characteristic, the retard start timing, its slope, and the total retard angle, thereby adjusting the ignition timing characteristics required by the engine. It is possible to respond.

Next, a modified example of the signal shaping circuit will be described with reference to FIGS. 4 and 5.

That is, FIG. 4 shows another embodiment of FIG. 1, in which the zener voltage of the zener diode 13 that detects the voltage of the signal generator 7 is divided by resistors 15 and 16.
By changing the values of 5 and 16, the retard start timing can be adjusted over a wide range.

FIG. 5 shows a second alternative embodiment in which a Zener diode 13 having switching characteristics, for example, a SIDAC 17 is connected.

Although the above description is applied to a capacitor charging/discharging type ignition device, the present invention can also be applied to other ignition devices operated by a control signal, such as a current interrupting type ignition device using a transistor or the like.

Further, although a voltage detection element such as a Zener diode 13 for detecting voltage is used as the state detection means, the same effect can be obtained by using other means for detecting the temperature, load, etc. of the engine.

As described above, the present invention controls the charge amount of the capacitor provided at the control input terminal of the signal generator and the switching element according to various engine conditions, and delays the activation timing of the switching element. A resistor inserted in the series circuit between the switching element and the signal generator.

With a simple configuration in which a series circuit consisting of a capacitor and a switching element is connected in parallel to this resistor, the ignition timing of the engine can be advanced in the low to medium speed range of the engine and retarded in the high speed range. The ignition timing characteristics required by the signal generator can be controlled arbitrarily, and since the desired advance angle characteristics can be obtained by using only one direction of the signal generator's AC output, the signal generator's output in the other direction can be controlled as desired. Since there is no influence, accurate advance angle characteristics can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing an embodiment of the present invention, Fig. 2 is a waveform diagram to explain the operation of the device shown in Fig. 1, and Fig. 3 is an ignition diagram to explain the operation of the device shown in Fig. 1. The timing characteristic curve diagrams, FIGS. 4 and 5 are electrical circuit diagrams showing other embodiments of the present invention, respectively. In the figure, 1 is a generator coil, 2, 8.11 is a diode, 3
, 10 is a capacitor, 4 is an ignition coil, 5 is a spark plug, 6 is a thyristor, 14 is a signal shaping circuit, 7 is a signal generator, 13 is a Zener diode, 9, 15, 16 are resistors,
17 is Psyduck.

Claims (1)

[Claims] 1. A signal generator that generates an alternating current output that is synchronized with the rotation of the engine and whose value increases or decreases as the rotation speed increases, a switching element that controls the energizing current of the ignition coil and generates the ignition voltage, and a switching element that A resistor connected only to the feed line of the one-way output of the AC output to the control input terminal, a capacitor connected in parallel with this resistor and charged only by the one-way output of the AC output, and the signal generator. It has a series circuit consisting of a switching element that becomes conductive when the output exceeds a predetermined value, and when the output of the signal generator does not reach the predetermined value, the output of the signal generator is connected to the switching element via only the resistor. By adding the switch to the switching element, the operating timing of the switching element is advanced in accordance with an increase in the output of the signal generator, and when the output of the signal generator exceeds a predetermined value, the switching element is made conductive to control the energization timing. An engine ignition system in which the charge charged in the capacitor is controlled in this way, and the timing of activation of the switching element is delayed in accordance with an increase in the output of the signal generator.