JPS6310329B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device suitable for use in gas appliances, petroleum appliances, etc., which uses a DC-DC converter using a battery as an input power source to discharge sparks between discharge electrodes, and which is suitable for use in gas appliances, oil appliances, etc. The present invention relates to an ignition device that includes a timer circuit that automatically stops spark discharge afterward, and a switch circuit that controls an external electric circuit in synchronization with the timer circuit.

Some conventional ignition devices are equipped with a timer circuit that stops spark discharge after a predetermined period of time, but none are equipped with a switch circuit that controls an external electric circuit in synchronization with this timer circuit. In addition, in a conventional ignition device equipped with a timer circuit, the timer circuit is constructed by connecting a switching transistor to the connection point of a resistor and a capacitor, and the potential of the capacitor increases after a predetermined period of time. There are some devices that make the switching transistor conductive, thereby suppressing the base voltage of the oscillation transistor of the DC-DC converter and stopping the oscillation. is difficult to discharge, and if the power switch of the ignition device is opened and then closed again before the capacitor is completely discharged, the operating time of the timer circuit becomes short.

The present invention has been made in view of these points, and is 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. An ignition device that is equipped with a timer circuit that accurately stops spark discharge at a preset predetermined time even if the circuit is closed again after the circuit is closed, and a switch circuit that controls an external electric circuit in synchronization with this timer circuit. The purpose is to provide the following.

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

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 to lower the voltage of the battery as an input power source. Its main feature is that it extracts a large DC voltage and uses this linear voltage to operate a timer circuit.

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

In Figure 1, 1 is a DC-DC converter,
For example, a battery 2 with a nominal voltage of about 1.2V to 1.5V is used as an input power source via a power switch 3, and a blocking oscillation circuit is formed of an oscillation transistor 4, a transformer 5, and the like. 6 and 7 are the base resistances of the oscillation transistor 4, and 8 is the 2 of the transformer 5.
This is a rectifier diode connected to the next side. Reference numeral 9 designates a spark discharge generating circuit, which includes a first switching element 13 connected in parallel to a series circuit of a capacitor 10 and the primary winding of a step-up transformer 12 having a discharge electrode 11 on the secondary side, and a resistor 14. Through the DC-
It is connected to the output side of DC converter 1.
This first switching element 13 is configured by a PPNPN diode (Shockley diode) 13a and a normal diode 13b connected in parallel with opposite polarities, and the cathode side of the PPNN diode 13a is installed in the direction in which it is connected to the step-up transformer 12. It is something that was given. 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 the battery 2 as an input power source is boosted by the DC-DC converter 1, and the boosted DC voltage is used to connect the capacitor 10 and the resistor 1.
Capacitor 1 with charging time determined by CR time constant of 4
0 is charged. When the first switching element 13 reaches a voltage that makes it conductive, 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 flow.
A spark discharge occurs at This spark discharge is sustained as long as the DC-DC converter is operating because the capacitor 10 is repeatedly charged and discharged at a predetermined cycle of the LC series resonant circuit of the capacitor 10 and the step-up transformer 12. .

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 discharged to a predetermined value by the DC voltage obtained from the DC-DC converter 1, which causes the first switching element 13 to conduct, and the discharge current of the capacitor 10 to the primary side of the step-up transformer 12. Flowing,
It is sufficient that the capacitor 10, the step-up transformer 12, and the first switching element 13 form a closed circuit. In addition, the first switching element 1
SCR can also be used for 3. When using an SCR, a circuit configuration as shown in FIG. 3 may be used, for example. In other words, in this circuit, when the oscillation voltage of the oscillation transistor 4 increases and reaches a predetermined value, the
This is designed to trigger the SCR.

17 is a timer drive winding wound magnetically coupled to the transformer 5 of the DC-DC converter 1; 18;
is a rectifier diode connected to this timer driving winding, and together with the smoothing capacitor 19 connected thereto, constitutes a rectifier circuit. 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 22, which will be described later. It is wound with the number of turns that satisfies the requirement. 20 is a timer circuit driven by the output voltage of the rectifier circuit consisting of the diode 18 and the capacitor 19;
A second switching element 21 such as an SCR (silicon controlled rectifier) connected between the connection point of the base resistors 6 and 7 of the oscillation transistor 4 of the DC-DC converter 1 and the ground is connected to the second switching element 21 of the DC-DC converter 1. PUT (PROGRAMABLE
UNIJUNCTION TRANSISTOR) 22. That is, the gate G of PUT22 is connected to the connection point between resistors 23 and 24, the anode A of PUT22 is connected to the connection point between resistor 25 and capacitor 26, and its cathode K
is connected to the second switching element 21 via the resistor 27.
It is connected to the gate G of the SCR that constitutes the . Note that 28 is an operation stabilizing resistor connected between the gate G and cathode K of the second switching element 21.

The thus configured timer circuit 20 operates as follows. Now, DC-DC converter 1
When the power switch 3 is closed and a DC voltage higher than the voltage of the battery 2 for driving the timer is taken out, a voltage divided by the resistors 23 and 24 is applied between the gate G and the cathode K of the PUT 22.
A voltage of a capacitor 26, which is charged in a charging time determined by a CR time constant of a resistor 25 and a capacitor 26, is applied between the anode A and the cathode K of the PUT 22. Therefore, after a predetermined period of time has elapsed, the voltage of the capacitor 26 changes from the gate G to the cathode K of PUT.
When the voltage applied between the two switches reaches a predetermined value, the PUT 22 becomes conductive and a predetermined voltage is applied to the gate G of the second switching element 21. 21 becomes conductive. Then, the base voltage of the oscillation transistor 4 is changed to the second switching element 21.
The oscillation is suppressed by the voltage between the anode A and the cathode K, and the oscillation is stopped. In other words, spark discharge at the discharge electrode 11 is stopped. The reason why the base resistors 6 and 7 of the oscillation transistor 4 are divided into two and the second switching element 21 is connected to the connection point is to ensure that the base voltage is suppressed when the switching element 21 becomes conductive. This is to ensure that the oscillation is stopped.

Note that when the PUT 22 becomes conductive, which causes the second switching element 21 to conduct and stops oscillation, no voltage is induced in the timer drive winding 17, so the timer circuit 20 receives the voltage of the battery 2. When only a small voltage divided by the rectifier diode 18 etc. is applied, the timer function stops, and as a result, the second switching element 2
No voltage is applied to the gate G of 1. However, once the second switching element 21 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,
The timer time is CR of resistor 25 and capacitor 26
Since it is determined by a time constant, the value can be set to a desired value. In the timer circuit configured in this way, the voltage of the capacitor 26 is almost discharged after the PUT 22 becomes conductive, so even if the power switch 3 is opened and then immediately closed, the predetermined voltage will not be reached. The timer time is obtained, and the inconvenience of shortening the timer time as in the conventional case does not occur. In other words, PUT2
The voltage of the capacitor 26 after 2 becomes conductive is such that it is charged with a small voltage obtained by subtracting the forward voltage of the rectifier diode 18, the voltage across the resistor 25, etc. from the voltage of the battery 2. The voltage supplied to the timer circuit 20 when the power switch 3 is once opened and then closed again is set to a value greater than the voltage of the battery 2 by the timer driving winding 17. This allows the timer time to be set with high precision.

Note that the timer circuit 20 is not limited to the above 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 like the above embodiment, and the capacitor 2
As the charging voltage of PUT 9 increases, the voltage between gate G and cathode K of PUT 22 decreases, and when it becomes lower than the voltage between anode A and cathode K,
PUT22 becomes conductive. After the PUT 22 becomes conductive, the voltage charged in the capacitor 29 is discharged through the resistor 31 and between the anode A and the gate G of the PUT 22, so the power switch 3
Even if the circuit is opened and then closed again, the predetermined timer time will be obtained. In other words, PUT22
After the capacitor 29 becomes conductive and the electric charge stored in the capacitor 29 is discharged, the capacitor 29 remains charged with a small voltage obtained by subtracting the forward voltage of the rectifier diode 18 from the voltage of the battery 2. , the voltage supplied to the timer circuit 20 when the power switch 3 is once opened and then closed again is applied to the battery 2 by the timer drive winding 17.
Since the voltage is set to be larger than the voltage of , the timer time can be set with high precision. Note that the resistor 30 determines the charging time of the capacitor 29, and the resistor 32 determines the charging time of the capacitor 29.
At the same time, a constant voltage is applied between the anode A and the cathode K of the PUT 22. The one shown in FIG. 5 uses a diac instead of the PUT, and when the charging voltage of the capacitor 34 exceeds a predetermined value, the diac 35 becomes conductive and triggers the second switching element 21. The charge stored in the capacitor 34 is transferred to the diagonal 3.
Even after being discharged when the battery 5 becomes conductive, it remains charged with the voltage obtained by subtracting the forward voltage of the rectifier diode 18, the voltage across the resistor 33, etc. from the voltage of the battery 2, but the voltage is not supplied to the timer circuit 20. The timer drive winding 17 makes the voltage of the battery 2 larger than the voltage of the battery 2.
As in the embodiment using PUT described above, the timer time can always be made highly accurate. Note that the resistor 33 determines the charging time of the capacitor 34. In any of the embodiments of the timer circuit 20 described above, the forward voltage is increased by, for example, using a plurality of rectifying diodes 18 connected to the timer drive winding 17 connected in series. This will further improve the accuracy of the timer time.

Furthermore, as is clear from the above description of the operation, the second switching element 21 may be any element that maintains the conductive state once it becomes conductive as long as the current does not drop below the holding current. It goes without saying that a triax or the like can also be used.

Reference numeral 36 denotes a switch circuit for controlling an external electric circuit, which is constructed by connecting a series circuit of a resistor 37 and a Zener diode 38 to the base of a transistor 39 as a fourth switching element, and the resistor 37 is used for driving the timer. It is connected to the cathode side of a diode 18 connected to the winding 17, and the emitter of a transistor 39 is connected to ground. In this switch circuit 36, when the power switch 3 is closed and the DC-DC converter 1 starts oscillating, the transistor 39 is turned on by the DC voltage obtained from the rectifier circuit connected to the timer drive winding 17. , closes the external electric circuit connected between the terminals 40 and 41. Then, after a predetermined time, the timer circuit 20
- When the oscillation of the DC converter is stopped, no voltage is induced in the timer drive winding 17, the transistor 39 becomes non-conductive, and the terminal 4
The external circuit between 0 and 41 is opened. Note that the resistor 42 connected to the collector side of the transistor 39 is for current limiting. In this way, the ignition device equipped with the switch circuit 36 controlled in synchronization with the timer circuit 20, for example,
Used in combustion appliances that use electromagnetic valves that open gas flow paths using the electromotive force of thermocouples. FIG. 6 schematically shows an example of its application, and its operation will be explained. In other words, numeral 43 is a gas flow path for a pilot burner, a main burner, etc., which is opened and closed by a solenoid valve 44. Now, turn on the ignition system power switch 3.
When closed, the solenoid valve 44 is forcibly opened by mechanical means or the like to release the gas, and the gas is ignited by the discharge at the discharge electrode 11 of the spark discharge generating circuit 9. When the thermocouple 45 is heated by the combustion of gas and sufficient electromotive force is generated,
The magnetic force generated by the electromagnetic coil 46 causes the electromagnetic valve 44 to
will be maintained in the open state. However,
Since the electromotive force of the thermocouple does not reach the predetermined value immediately, the ignition is performed via the switch circuit 36, which remains conductive until the oscillation of the DC-DC converter 1 is stopped by the timer circuit of the ignition device. The battery 2, which is the input power source for the device, is connected to the electromagnetic coil 46, thereby maintaining the electromagnetic valve 44 in an open state. By the time the switch circuit 36 becomes non-conductive in synchronization with the timer circuit that stops the oscillation of the DC-DC converter 1, the electromotive force of the thermocouple 45 is reduced to the electromotive force of the solenoid valve 4.
Since the value is sufficient to open the valve 4, after the spark discharge at the discharge electrode 11 stops and the switch circuit 36 becomes non-conductive, the electromagnetic valve 44 only receives the electromotive force of the thermocouple 45. The valve will remain open.

Note that the configuration of the switch circuit 36 is not limited to that of the above embodiment, and various modifications are possible. For example, only the resistor 37 may be connected to the transistor 39 without the Zener diode 38, or the resistor 37 may be omitted if the Zener voltage of the Zener diode 38 is selected to have a high value. Also. Resistor 42 is connected to terminal 4
Connect to the external circuit side connected between 0 and 41,
Depending on the external circuit connected between the terminals 40 and 41, this may not be necessary. Furthermore, in place of the transistor 39 as the fourth switching element constituting the switch circuit, a light emitting diode 47 and a phototransistor 48 may be used, for example, with a circuit configuration as shown in FIG. Furthermore, a photocoupler may be used instead of the light emitting diode 47 and phototransistor 48. Furthermore, although the DC voltage for controlling the fourth switching element of the switch circuit 36 is taken from the rectifier circuit connected to the timer drive winding 17 in the above embodiment, it is taken from a predetermined connection part of the timer circuit 20. Take it out, install a switch circuit drive winding in the transformer of the DC-DC converter,
The point is to connect a rectifier circuit there and take out the DC
-Any device that utilizes the voltage generated from a DC converter will suffice.

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 will always be stopped at a time close to the preset time, and the spark discharge will always be stopped at a time close to the preset time. In addition to ensuring ignition, there is no need to set the timer time well in advance, so no extra power is consumed, and as a result, the life of the battery can be extended. Furthermore, since it operates reliably with a low input power supply, there is no need to increase the number of batteries, and the overall size of the device can be reduced. Furthermore, since it is equipped with a switch circuit that is controlled in synchronization with a highly accurate timer circuit, the control of external electric circuits connected to this switch circuit is also reliable, and various other excellent effects are achieved. play.

[Brief explanation of the drawing]

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 circuit diagram showing a modified example of the timer circuit section of the ignition device according to the present invention, FIG. 6 is a circuit diagram showing an application example of the ignition device according to the present invention, and FIG. 7 is a circuit diagram showing an example of the application of the ignition device according to the present invention. FIG. 7 is a circuit diagram showing a modification of the switch circuit section of the device. 1...DC-DC converter, 2...Battery, 3...
...Power switch, 9...Spark discharge generation circuit, 17
...Timer drive winding, 18... Rectifier diode, 19... Smoothing capacitor, 20... Timer circuit, 36... Switch circuit.

Claims (1)

[Claims] 1 A timer circuit that connects a spark discharge generation circuit consisting of a closed circuit of a capacitor, a step-up transformer, and a first switching element to the output side of a DC-DC converter that uses a battery as an input power source, and controls the spark discharge generation circuit. and a switch circuit that controls an external electric circuit in synchronization with the timer circuit, the timer circuit comprising a timer drive winding provided in the transformer of the DC-DC converter. a second switching element that operates with a DC voltage larger than the battery of the input power source taken out from the DC-DC converter via a rectifier circuit, and connected between the base circuit of the oscillation transistor of the DC-DC converter and the ground; and a third switching element that makes the switching element conductive after a predetermined period of time, and the switch circuit includes a fourth switching element that is operated by the DC voltage taken out from the DC-DC converter. An ignition device featuring: