JPH035118Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a microwave oven equipped with a cooking heater whose energization time is adjusted by a timer motor.

[Prior art]

In a conventional microwave oven of this type, a surge current prevention circuit having a configuration shown in FIG. 2 was installed as a measure to prevent the generation of surge current during operation of the microwave oven.

That is, in the circuit shown in FIG. 2, power supply lines 3a and 3b are connected to a power supply 2 with an operating switch 1 interposed therebetween, while oven current lines 4a and 4b and heater current lines 5a and 5b are connected to the power supply lines 3a and 3b. In this configuration, the excitation coil 8b of the anti-surge relay 8 is connected between the range energizing paths 4a and 4b for energizing the range transformer (high voltage transformer) 7. At the same time, a normally open contact 8a of the surge protection relay 8 is interposed in the middle of the energizing path 4a closer to the transformer 7 than the connection point of the excitation coil 8b, and a surge current prevention contact is provided in parallel to the normally open contact 8a. A resistor 9 is connected thereto.

In the circuit configured as described above, when the operation switch 1 is closed and the changeover contacts 6a ₁ and 6a ₂ of the changeover switch 6 are connected to the range energizing paths 4a and 4b for range operation, the surge countermeasure relay 8 is energized. At the same time as the coil 8b is energized, the range transformer 7 is also energized via the surge current prevention resistor 9, and the surge current generated during the switching operation of the changeover switch 6 is suppressed by the surge current prevention resistor 9. Absorbed and removed. Since the normally open contact 8a of the surge countermeasure relay 8 closes after a short delay time after the excitation coil 8b is energized, the surge current is absorbed during this delay time, and the surge current is absorbed. Thereafter, the terminals of the surge current prevention resistor 9 are short-circuited by the normally open contact 8a, and normal range operation is performed.

In the above-mentioned case where the changeover switch 6 is switched to the range operation side, in this circuit, the heating path 5 connected to the cooking heater 10 and the timer motor 11 that adjusts the energization time of the heater 10 is connected.
The a and 5b sides are completely disconnected from the power supply 2.

However, in the surge current prevention circuit in the conventional example described above, it is necessary to separately prepare a surge current prevention resistor 9 in order to absorb and remove the surge current.
This has the drawback of increasing the number of parts and wiring connections, resulting in increased costs.

[Purpose of invention]

The present invention has been made in consideration of the above-mentioned problems in the conventional example, and it is an object of the present invention to provide a microwave oven in which a surge current prevention circuit is constructed with a reduced number of parts.

[Structure of the idea]

The microwave oven of the present invention is equipped with a cooking heater whose energization time is adjusted by a timer motor, and is equipped with a surge current prevention circuit that also uses the timer motor as a resistance element for surge current prevention during microwave operation. , thereby omitting the provision of a separate resistance element for surge current prevention.

〔Example〕

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

FIG. 1 shows the circuit configuration of the microwave oven of this embodiment, in which an operation switch 14 is interposed between power supply lines 13a and 13b connected to a power supply 12. 1
3a, 13b are connected to microwave current conduction paths 16a, 16b and heater current conduction paths 17a, 17b via a changeover switch 15, respectively.

A range transformer (high-voltage transformer) 19 is connected to the range power supply paths 16a and 16b via a normally open contact 18a of a surge countermeasure relay 18, while a power supply 12
The excitation coil 18b of the anti-surge relay 18 and the switch 20 are connected between the nearby energizing paths 16a and 16b.
are connected in series. The switch 20 is connected to the changeover switch 15 by one multipole switch.
When the changeover contacts 15a ₁ , 15a ₂ of the changeover switch 15 are switched and connected to the range energizing paths 16a, 16b, they are closed, and the heater energizing paths 17a, 17b are connected. It is configured to open when switched to the side.
Also, in this way, the switch 20 and the changeover switch 15
By using a single multi-pole switch, the number of parts and wiring connections can be reduced.

On the other hand, the heater current paths 17a and 17b include a cooking heater 21 and a normally closed time switch 22.
are connected in series, and a heater timer motor 23 is connected in parallel to this series circuit, so that the normally closed time switch 22 is opened by the heater timer motor 23.

Further, the heater timer motor 23 is connected in parallel to the normally open contact 18a of the range energizing path 16a, and is configured to form a surge current prevention circuit together with the surge countermeasure relay 18 and switch 20. There is.

That is, the heater timer motor 23 is commonly used as a resistive element for absorbing surge current that bridges both terminals of the normally open contact 18a of the surge protection relay 18.

In the above circuit configuration, the operating switch 14 is closed and the changeover switch 15 is connected to the range energizing path 16.
When the switch 20 is closed and the excitation coil 18b of the anti-surge relay 18 is energized, the power is energized via the heater timer motor 23. The range transformer 19 is also energized,
The surge current generated at the start of range operation is absorbed and removed by the resistance element of the heater timer motor 23. The normally open contact 18a of the anti-surge relay 18 closes after a short delay after the excitation coil 18b is energized. Therefore, the surge current is absorbed during this delay time, and thereafter, the normally open contact 18a is closed to short-circuit both terminals of the heater timer motor 23, and normal range operation is performed.

When operating the cooking heater, switch 1
Since the switch 20 is in the open state in conjunction with the switch 20, the excitation coil 18b of the anti-surge relay 18 is not energized.
There is also no power supply.

[Effect of idea]

The microwave oven of the present invention has a structure in which a surge current prevention circuit is constructed by using the timer motor, which adjusts the energization time of the cooking heater, as a resistance element for surge current prevention during microwave operation, as described above. There is no need to prepare a separate surge current prevention resistor as in the conventional example, and the number of parts and wiring connections can be reduced. Surge current can be reliably prevented with a simple configuration, and costs can also be reduced. It is possible to achieve excellent effects such as being able to achieve the desired results.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
The figure is a circuit diagram showing a conventional example. 15 is a changeover switch; 16a and 16b are power supply paths for the range; 17a and 17b are power supply paths for the heater;
8 is a surge protection relay, 18a is a normally open contact, 1
8b is an excitation coil, 19 is a range transformer, 2
0 is a switch, 21 is a cooking heater, 22 is a normally closed time switch, and 23 is a timer motor for the heater.

Claims (1)

[Scope of utility model registration request] In a microwave oven equipped with a cooking heater whose energization time is adjusted by a timer motor,
A microwave oven comprising a surge current prevention circuit that also uses the timer motor as a resistance element for surge current prevention during microwave operation.