JPH048868A - Capacitor charging and discharging ignition device - Google Patents

Abstract

PURPOSE:To restrain a loss in resistance or the like due to the half-wave voltage of exciter output in a negative direction through the application of simple constitution by adding a diode between the anode of a thyrister for discharging the electric charge of a capacitor and the grounding thereof for allowing the passage of the half-wave voltage of exciter output in a negative direction. CONSTITUTION:The positive side half-wave of output from an exciter EXT is charged to a capacitor C1 and turns into ignition energy. Also, the negative side half-wave thereof is fed back from a resistor R1 via a diode D2. When a potential difference across the resistor R1 exceeds the gate trigger voltage of a thyrister S1, however, this thyrister S1 is ignited due to output from the exciter EXT and turned on. Then, the aforesaid negative side half-wave output is fed back from a diode D5 to the exciter EXT via a circuit between the anode and cathode of the thyrister S1, and a diode D2. Consequently, a time for the negative side half-wave output to pass the resistor R1 is extremely as short as duration from the ignition to turning-on of the thyrister S1, thereby substantially reducing a resistance loss in the resistor R1 due to the output from the exciter EXT.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitor charging/discharging type ignition device which has a simple configuration and is characterized by suppressing loss in resistance and the like due to negative half-wave voltage of exciter output.

FIG. 1 is a circuit diagram of a conventional capacitor charge/discharge type ignition device. The ignition capacitor C1 is charged through the rectifier diode D1 with the output positive half-wave voltage of the exciter EXT.Then, the thyristor S1 is fired with the negative half-wave voltage of the exciter EXT output, and the charge in the capacitor CI is discharged. Then, the ignition coil Ign,C generated an ignition pulse to generate a spark at the plug SP. At this time,
Since most of the exciter EXT output is consumed as a loss in the resistor R1, a resistor with an extremely large loss is used as the resistor R1.

In order to solve the above-mentioned drawbacks, the present invention provides a capacitor charging/discharging type ignition device that can suppress the loss of the load resistance of the negative half wave of the exciter EXT by adding a simple additional circuit to the conventional circuit. It is something.

The present invention will be explained below using the drawings. FIG. 2 is a circuit diagram of one embodiment of the present invention. EXT is exciter coil, Ign, C is ignition coil, E is ground, C
1 is a capacitor for ignition, D1 is a diode for rectifying the positive half wave of the exciter EXT output, Sl is a thyristor for discharging the capacitor C1, D2 is a diode for preventing commutation of the positive half wave of the exciter output, and D3 is a diode for rectifying the positive half wave of the exciter output. A diode, R, for diverting the potential of the thyristor S1 from the ground point.
] is a resistor connected in parallel to the diode D3 and adjusts the ignition timing by creating a potential difference across the resistor by the negative half-wave output of the exciter EXT; R2 is a resistor for limiting the keto current of the thyristor S1; D5 is a diode that commutates the half-wave output of the exciter EXT without passing through the resistor R1 after the thyristor S1 is turned on;
The positive half wave of the XT output is charged in the capacitor C1 and becomes energy for ignition. The negative half wave of the exciter EX'T passes from the resistor R1 through the diode D2 to the exciter E.
When the potential difference across the resistor R1 becomes larger than the gate trigger voltage of the thyristor S1, the thyristor S1 is turned on and conductive by the output of the exciter EXT.

When the thyristor S1 becomes conductive, the negative half-wave output of the exciter EXT passes from the diode D5 between the anode and cathode of the thyristor S1 and through the diode D2 to the exciter E.
Return to XT. Therefore, the time the exciter EXT negative half-wave output passes through R1 is only for a very short period of time until thyristor $1 fires and becomes conductive, and the loss due to the exciter EXT output of R1 can be significantly reduced.

In this way, by adding the exciter-EXT negative half-wave output feedback diode, the loss of the feedback resistor for the exciter-EXT negative half-wave output can be significantly reduced, making it possible to use a small and inexpensive capacitor. It has great practical effects as a charge-discharge type ignition device.

[Brief explanation of the drawing]

FIG. 1 is a conventional capacitor charge/discharge type ignition device, and FIG. 2 is a circuit diagram of an embodiment of the present invention. In the figure, Di, D2, D3. D4 and D5 are diodes, Sl is a thyristor, C1 is a capacitor, R1 and R2 are resistors, EXT is an exciter coil, 1, . . . C is an ignition coil, SP is a plug, and E is a ground.

Claims (1)

[Claims] A capacitor charging device in which the charge of a capacitor charged via a diode that rectifies the positive half-wave voltage of the exciter output is discharged by a thyristor fired by the negative half-wave voltage of the exciter output. A capacitor charging/discharging type ignition device, characterized in that a diode is added between the anode of the thyristor and ground to allow a negative half-wave voltage of the exciter output to pass through.