JPS5941345Y2 - Capacitor charge/discharge type ignition device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a capacitor charging/discharging type ignition device, and in particular provides a simple ignition device that can keep the ignition timing (angle) constant.

The present invention will be explained in detail below using the drawings.

Figures 1 and 2 are circuit diagrams of an embodiment of the present invention and operation waveform diagrams of each part thereof. In the figures, EXT and P are a power generation coil and a signal generation (pulsar) coil of a magnet generator or the like rotated by an internal combustion engine. , Dl, D3 are diodes, C2 is an ignition power supply capacitor charged by the voltage generated by the generator coil EXT, Ig is an ignition coil, n 1
> n 2 is its primary and secondary winding, Ip is the spark plug,
SCR is a gate-poled thyristor whose gate G is controlled and conductive by a signal from the ignition signal generating coil p via a switch circuit SW, which will be described later. A spark is generated in the ignition plug Ip via the secondary winding n2.

SW is a switch circuit that constitutes the main part of the device, and includes a series circuit of a diode D2 and an ignition signal charging capacitor C1 connected across the ignition signal generating coil P, and a discharging circuit connected in parallel to the series circuit. A pace and an emitter are connected between resistor R2 and the diode D2, and
It consists of a transistor Q1 and the like whose collector is connected to the gate G of the thyristor SCR.

(In the figure, R1 is a resistor for limiting the charging current of the capacitor C1, and R3 is a resistor for limiting the gate current of the thyristor SCR.

) This constitutes the device of this invention.

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

First, FIG. 2a shows the voltage waveform generated by the power generating coil EXT, or the signal (voltage) waveform of the signal generating coil P.
It is assumed that .

First, when the polarity of the generator coil EXT is up is ■, the capacitor C
2 is charged through the path of diode D3 → capacitor C2 → ignition coil primary n1 → EXTe).

When the polarity of the generator coil EXT is ○ on the top and ``on'' on the bottom, the capacitor C2 is blocked by the diode D3 and is not charged.On the other hand, the charge of the capacitor C2 that was charged during the first half cycle is discharged from the discharge circuit. Since there is no such thing, this state will be maintained.

(See Figure 2C) However, since the voltage generated by the signal generating coil P is set to be out of phase with the generating coil EXT by 900 degrees, when the polarity of the generating coil EXT is lowered to e, that is, at time t2. Between t4 and t4, the upper polarity becomes [present].

(Refer to FIG. 2) Therefore, during this time, the capacitor C1 is charged along the path of signal generating coil P⊙→diode D1→resistance R1→diode D2→capacitor C1→signal generating coil Pe.

Then, at time t3, when the signal (voltage) of the signal generating coil p reaches the maximum peak value, the capacitor C1 is no longer charged after this point, and the peak value of the signal is in the process of falling from the peak. Between time t3 and t4, the potential on the cathode side of diode D2 (ie, the fourth charging position of capacitor C1) becomes higher than the potential on the anode side.

When this potential difference exceeds the base-emitter voltage (VBE) of the transistor Q1, the charge in the capacitor C1 is discharged through the path of capacitor C1 → emitter/base of transistor Q1 → resistor R2 → capacitor C1, making the transistor Q1 conductive. And the charge is transferred to C1→transistor Q1 emitter/collector→SCR gate G→
It is discharged through the path of the capacitor C1 and supplies power to the SCR as a gate current.

Therefore, at time Δt3, SCR becomes conductive, and the charge of ignition power supply capacitor C2 changes from capacitor C2→SCR-
As a result of the rapid discharge in the path of the ignition coil Ign1 (FIG. 2e), a spark is generated in the ignition plug Ip via the secondary coil n2.

Repeat this operation below.

In other words, since the present invention makes the SCR conductive (trigger) by a switch circuit that operates near the maximum wave height (peak) of the ignition signal, it depends on the magnitude of the ignition signal voltage of the signal generating coil P, that is, the rotation speed of the internal combustion engine. Regardless, the phase angle (
What about the generator coil EXT! sparks can be generated near the peak).

Figures 4a, b, and c are diagrams of other embodiments of switch circuits that can be applied to the present device. , thereby stabilizing the firing timing of the thyristor SCR.

Further, in Fig. b, an amplifier transistor Q2 is further connected to the transistor Q1, and the gate current of the thyristor SCR is obtained from the ignition signal of the ignition signal generating coil via the transistor Q2.

Figure C shows the transistor Q1. of the switch circuit SW. N-gate thyristor PUT (so-called Progla
mmable UnijunctionTransis
In this example, the charging voltage of the capacitor C1, that is, the N-gate thyristor P
When the voltage at the anode A of the UT becomes higher than the voltage at the gate G, it is discharged along the path of capacitor C1 → anode A of the thyristor PUT, gate G → resistor R5 → resistor R2 → capacitor C1, making the P-gate thyristor PUT conductive. This is what I did.

As is clear from the above explanation, according to the present invention, a constant ignition (angle) characteristic can be obtained regardless of the engine speed by simply adding a simple switch circuit. Practical effects such as being suitable are thick% b

[Brief explanation of drawings]

1 and 2 are circuit diagrams and operation waveform diagrams of each part of the device of the present invention, and FIG. 3 is a characteristic diagram showing the relationship between ignition timing (angle) and engine speed of the device of the present invention. FIGS. 4a, 4b, and 4c are diagrams showing other embodiments of switch circuits applicable to the present device, respectively. In the figure, EXT is a power generation coil, P is an ignition signal generation coil, C2 is an ignition power supply capacitor, SCR is a thyristor, G is its gate electrode, Ig is an ignition coil, Ip is a spark plug, SW is a switch circuit, Di, D2 is a diode, C1 is a capacitor, R2 is a discharge resistor, Ql
is a transistor, Q2 is an amplification transistor, PUT is an N-gate thyristor, and TR is a temperature compensation element (thermistor).

Claims (1)

[Scope of utility model registration request] A capacitor charging/discharging type ignition device that charges a capacitor with the voltage generated by a power generating coil, and discharges the charge of the capacitor to the ignition coil via a thyristor which is conducted by the ignition signal of the ignition signal generating coil to ignite. Finally, a series circuit of a diode and a capacitor is connected in parallel to the series circuit, and a series circuit of a diode and a capacitor is connected between both ends of the ignition signal generation coil having a phase difference of 90 degrees from the generation coil through a temperature maintaining element. A switch circuit including a transistor whose base and emitter are connected between a discharge resistor and both ends of the diode, and whose collector is connected to the gate of the thyristor is used to make the thyristor conductive, thereby controlling the ignition timing. A capacitor charging/discharging type ignition device characterized by having a constant angle (angle).