JPS608624A - Ignition device with timer circuit - Google Patents

Abstract

PURPOSE:To provide a positive operation of timer circuit even under a low voltage of battery by a method wherein a timer operating winding is magnetically coupled to a transformer of DC-DC convertor, a rectifier circuit is connected to the winding so as to take out DC voltage higher than a voltage of battery applied as an input power supply. CONSTITUTION:A rectifier diode 19 connected to a timer driving winding 18 which is magnetically coupled to a transformer 5 of DC-DC convertor 1 constitutes a rectifying circuit together with a smoothing capacitor 20. DC voltage got from this rectifier circuit is required to be higher than a voltage of bettery 2 and so the timer driving winding 18 is wound with the number of windings required for fulfilling the condition. Thereby, a voltage supplied to the timer circuit 21 when the power supply switch 3 is closed again after the power supply switch 3 is opened once is set to become a value higher than the voltage of the battery 2 due to the presence of the timer driving winding 18, so that it is possible to have a fine accurate time of timer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device suitable for use in gas appliances, oil appliances, etc., which uses a DC-DC inverter with a battery as an input power source to discharge sparks between discharge electrodes. The present invention relates to an ignition device with a timer circuit that automatically stops spark discharge after a predetermined period of time.

In conventional ignition devices of this type, the timer circuit is constructed by connecting a switching transistor to the connection point between a resistor and a capacitor, and when the potential of the capacitor rises after a predetermined period of time, the switching transistor becomes conductive. The oscillation 1 of the DC-DC converter is caused by
~IJ has been proposed in which the base voltage of the transistor is suppressed to stop oscillation. However, with a device configured like this, the electricity charged in the capacitor begins to discharge, and once the power switch of the ignition device is opened, if the switch is closed again before the capacitor is completely discharged, the timer will start. The problem was that the operating time of the circuit was shortened.

The present invention has been made in view of these points, and therefore, in an ignition device that uses a DC-DC converter that uses a battery as an input power source to cause a spark discharge between discharge electrodes, after the power switch is once circuited. It is an object of the present invention to provide an ignition device with a timer circuit, which is equipped with a timer circuit that accurately stops spark discharge at a predetermined time even if the circuit is closed again.

Another object of the present invention is to provide an ignition device with a timer circuit in which the timer circuit operates reliably even when the voltage of a battery as an input power source is low.

To this end, the present invention provides a timer drive winding that is magnetically coupled to the transformer of the DC-DC converter, and connects a rectifier circuit to the timer drive winding so that the voltage of the battery as an input power supply is lower than that of the battery. It is characterized by extracting a large DC voltage and using this DC voltage to operate a timer circuit.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, 1 is a DC-DC converter, for example, a battery 2 with a low electromotive force with a nominal voltage of about 1.2 to 1.5V is used as a human power source via a power switch 3, and an oscillation transistor 4, a transformer 5, etc. It consists of a blocking oscillation circuit composed of.

6.7 is the base resistance of the oscillation transistor 4, and 8 is a rectifier diode connected to the secondary side of the transformer 5. 9
1 is a spark discharge generation circuit, in which a first switching element 13 is connected in parallel to a series circuit of a capacitor 10 and the primary winding of a step-up transformer 12 which has a discharge electrode 11 on the secondary side, and is connected through a resistor 14. and is connected to the output side of the DC-DC converter 1. This first switching element 13 is configured by a PNPN diode (Shockley diode) 13a and a normal diode 13b connected in parallel with opposite polarities, and l) the cathode side of the NPN diode 13a is connected to the step-up transformer 12. It is installed in the direction in which it will be exposed. The configuration up to this point is a circuit of a conventionally known ignition device, and operates as follows.

In other words, the DC voltage of battery 2 as an input power source is DC-O
The voltage is boosted by the C converter 1, and the boosted DC voltage charges the capacitor 10 in a charging time determined by the 08 time constant of the capacitor 10 and the resistor 14. and,
When the voltage at which the first switching element 13 becomes conductive is reached, the discharge current of the capacitor 10 flows through the primary side of the step-up transformer 12, and the voltage induced on the secondary side causes the discharge electrode 11 to
A spark discharge occurs at This spark discharge is caused by the capacitor 10 repeating charging and discharging at a predetermined period of the C series co-imaging circuit of the capacitor 10 and the step-up transformer 12.
This will continue while the DC-DC converter is operating.

It goes without saying that the spark discharge generating circuit 9 is not limited to the above-mentioned configuration, but may have the circuit configuration shown in FIG. 2. In short, the capacitor 10 is charged 4 to a predetermined value with the DC voltage obtained from the DC-DC-1 inverter 1, which causes the first switching element 13 to conduct and connect the capacitor 10 to the primary side of the step-up transformer 12. It is only necessary that the capacitor 10, the step-up transformer 12, and the first switching element 13 form a closed circuit so that the discharge current flows.

Further, an SCR can also be used for the first switching element 13. When using an SCR, a circuit configuration as shown in FIG. 3 may be used, for example. That is, in this circuit, when the oscillation voltage of the oscillation transistor 4 rises to a predetermined value, the SCR is triggered to 1 via the resistor 15 and the Zener diode 16. A resistor 17 connected between the gate and cathode of this SCR
is the operation stabilizing resistance.

18 is a timer drive winding wound around the transformer 5 of DC-DC converter 1 in a magnetically coupled manner; 19 is a rectifier diode connected to this timer drive winding; and smoothing content 4 connected to this. A rectifier circuit is configured with the filter 20. The DC voltage obtained from this rectifier circuit needs to be higher than the voltage of the battery 2 as the input power source in order to stably operate the PUT 23, which will be described later. It is wound with the number of turns t that satisfies the following. 21 is a timer circuit driven by the output voltage of the rectifier circuit consisting of the diode 19 and the capacitor 20, and is connected between the base resistor of the oscillation transistor 4 of the DC-DC converter 1 and the connection point of 7 and the ground. A second switching element 22 such as an SCR (silicon controlled rectifier) is connected to a DC-
A PUT (PROGRAMA
BLE UNIJUNCTION TRANSISTO
R) Contains 23/v. In other words, P
The gate G of the UT23 is connected to the connection point of the resistor 24.25, the anode A of the PUT23 is connected to the connection point of the resistor 26 and the capacitor 27, and the cathode thereof is connected to the connection point of the resistor 24.25.
S forming the second switching element 22 via
Connected to gate G of CR. Note that 29 is an operation stabilizing resistor connected between the gate G and cathode of the second switching element 19. The timer circuit 21 configured in this manner operates as follows.

Now, when the power switch 3 of the DC-DC converter 1 is closed and a DC voltage higher than the voltage of the battery 2 for driving the timer is taken out, a voltage is divided between the gate G and the cathode of the PtJT 23 by the resistor 24.25. The voltage of the capacitor 27 which is charged in the charging time determined by the CR time constant of the resistor 26 and the capacitor 27 is applied between the anode A and the cathode of the PUT 23. Therefore, when a predetermined period of time passes and the voltage of the capacitor 27 becomes a value higher by a predetermined value than the voltage applied between the G-force swords of the PtJT 23, the PL
IT23 becomes conductive and the second switching element 2
A predetermined voltage is applied to the second gate G, and the second switching element 22 becomes conductive. Then,
The base voltage of the oscillation transistor 4 is suppressed by the voltage between the anode A and the cathode of the second switching element 22, and oscillation is stopped. In other words, spark discharge at the discharge electrode 11 is stopped. The reason why the base resistor 6.7 of the oscillation transistor 4 is divided into two and the second switching element 22 is connected to the connection point is to ensure that the base voltage is suppressed when the switching element 22 becomes conductive. This is to ensure that the oscillation is stopped.

Note that when the PUT 23 becomes conductive, the second switching element 22 becomes conductive, and oscillation stops.
Since no voltage is induced in the timer drive winding 18, only a small voltage obtained by dividing the voltage of the battery 2 by the rectifier diode 19 etc. is applied to the timer circuit 21, and the timer function stops. , no voltage is applied to the gate 1-G of the second switching element 22. However, once the second switching element 22 becomes conductive, it remains conductive unless the current flowing therein becomes equal to or less than the holding current, and oscillation does not start again. As is clear from the above explanation of the operation of the timer circuit, one hour of the timer is determined by the CR time constant of the resistor 26 and the capacitor 27, so the value can be set to a desired value. In the timer circuit configured in this way, the voltage of the capacitor 27 after PUT 23 becomes conductive is in a state where it is largely discharged, so the circuit is closed immediately after the power supplies 2 and 3 are closed. Also, the predetermined timer hour can be obtained, and there is no inconvenience that the timer hour becomes shorter than in the conventional case. In other words, the voltage of the capacitor 27 after the PUT 23 becomes conductive is such that it is charged with a small voltage obtained by subtracting the forward voltage of the rectifier diode 19, both voltages of the resistor 26, etc. from the voltage of the battery 2. On the other hand, when the power switch 3 is once closed and then closed again, the voltage supplied to the timer circuit 21 is set to a value larger than the voltage of the battery 2 by the timer drive winding 18. It is possible to make the timer one hour highly accurate.

Note that the timer circuit 21 is not limited to the above-mentioned configuration, but may have a configuration as shown in FIG. 4 or FIG. 5, for example. The one shown in FIG. 4 uses a PUT similar to the above embodiment, and as the charging voltage of Contin (j-30 increases, the voltage between the gate 1 and the cathode of PUT 23 decreases, When the voltage between the anode A and the power source becomes lower than the voltage between the power source and the anode A, the PUT23 becomes conductive.After the PUT23 becomes conductive, the voltage charged in the capacitor 30 is the voltage between the resistor 32 and the PUT23. Anode A
-Gate G, so the power switch 3
Even if the circuit is closed again after the circuit is completed, the predetermined one hour timer will be obtained. In other words, even after the electric charge stored in the capacitor 30 is discharged after the PtJT 23 becomes conductive, the capacitor 30 remains charged with a small voltage obtained by subtracting the forward voltage of the rectifier diode 19 from the voltage of the battery 2. However, when the power switch 3 is once closed and then closed again, the voltage supplied to the timer circuit 21 is set to a value larger than the voltage of the battery 2 by the timer drive winding 18. , it is possible to make the timer one hour highly accurate. In addition,
The resistor 31 determines the charging time of the capacitor 30, and the resistor 33, together with the resistor 32, applies a constant voltage between the anode and cathode of the PUT 23.

The one shown in FIG. 5 uses a diac instead of a PUT, and when the charging voltage of the capacitor 35 exceeds a predetermined value, the diac 36 becomes conductive and triggers the second switching element 22. The capacitor 35 remains charged at a voltage obtained by subtracting the forward voltage of the rectifier diode 19, the voltage across the resistor 34, etc. from the voltage of the battery 2 even after the charge stored therein is discharged when the diac 36 is turned on. However, since the voltage supplied to the timer circuit 21 is set to a value larger than the voltage of the battery 2 by the timer drive winding 18, the above embodiment using I') UT Similarly, the timer 1 hour can always be made highly accurate. In addition, resistance 3
4 determines the charging time of the capacitor 35.

In any of the embodiments of the timer circuit 21 described above,
For example, if the forward voltage is increased by connecting a plurality of rectifier diodes 19 connected to the timer drive winding 18 in series, it is possible to further increase the timer hour by 16 degrees. can.

Furthermore, as is clear from the above description of the operation, the second switching element 22 may be any element that maintains the conductive state as long as the holding current does not drop below the holding current once it becomes conductive. Needless to say, it is also possible to use the following.

Since the ignition device of the present invention is configured as described above, even if the power switch is once opened and then closed again, the spark discharge is always stopped at a time close to the preset time, and the ignition of gas appliances, etc. In addition, since there is no need to set the timer with a margin of one hour, no extra power is consumed, and as a result, the life of the battery can be extended. Furthermore, since the device operates reliably with a low input power source, there is no need to increase the number of batteries, and various effects are achieved, such as the ability to promote miniaturization of the entire device.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an ignition device according to an embodiment of the present invention, FIGS. 2 and 3 are circuit diagrams showing modified examples of the spark discharge generating circuit section of the ignition device according to the present invention, and FIG. FIG. 5 is a diagram showing a modification of the timer circuit section of the ignition device according to the present invention. 1...DC-DC converter, 2...Battery, 3...
・Power switch, 9...Spark discharge generation circuit, 18...
・Timer drive winding, 19... Rectifier diode, 2
0... Smoothing capacitor, 21... Timer circuit. Patent applicant Murata Manufacturing Co., Ltd.

Claims (1)

[Claims] An ignition device comprising a spark discharge generating circuit configured with a closed circuit of a capacitor, a step-up transformer, and a first switching element is connected to the output side of a DC-DC converter that uses a battery as an input power source, wherein the DC-DC converter A timer drive winding is magnetically coupled to the transformer of the timer, and a rectifier port i is connected to the timer drive winding to extract a DC voltage higher than that of the battery of the input power source, and the system is operated by this DC voltage. A timer circuit including a third switching element that makes the second switching element conductive after a predetermined time;
An ignition device with a timer circuit, characterized in that the ignition device is connected between a base circuit of an oscillation transistor of a DC converter and ground.