JPS601511Y2 - High frequency heating device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to cooling of a microwave oven with a heater.

Microwave ovens selectively heat the food inside the heating chamber using high frequency waves, so the temperature inside the heating chamber does not rise much, making it an efficient cooking appliance.

However, on the other hand, so-called oven dishes that require browning of bread, gratin, etc. require the temperature of the heating chamber to be raised to a certain degree, which is not possible with high-frequency heating.

In order to overcome this drawback, a microwave oven with a heater has been considered in which a heating element such as a sheathed heater is installed inside the oven to enable oven cooking.

However, because the temperature inside the oven is high, the interior remains hot even after being used as an oven.

Generally, microwave ovens guide cooling air from the Macnetron into the oven to prevent the interior from becoming cloudy with moisture from food and from forming water droplets during microwave cooking.

Therefore, by utilizing this, the present invention realizes a circuit that rotates a magnetron cooling fan motor for a certain period of time after the end of oven cooking, and uses the wind to cool the inside of the oven.

A circuit that realizes the above operation will be explained below based on the drawings.

Reference numeral 1 designates a changeover switch between the high frequency heating circuit and the heater heating circuit, and by turning the time switch for high frequency heating, the contact 2 enters the No side and the oven lamp 3 is turned on.

When the door is closed and the contact point of the door switch 4 enters the NC side, the timer motor 5 starts to operate, and when the cooking button is pressed and the latch switch 6 is closed, the fan motor 8 for cooling the magnetron 7 rotates, and the transformer 9 is turned on. A high voltage is applied to the secondary side, causing the magnetron 7 to oscillate.

On the other hand, when the changeover switch is turned to the No side and the spring-type timer 11 for the heater 10 is turned, the contact is turned to the No side and the heater is energized.

This wind-up timer has three different states per contact, and when the contact turns off after a period of time, voltage is applied to both ends of the coil of the power relay 12, and the contact enters the No side, turning the fan motor on. As the oven rotates, the air generated by the rotation of the fan dissipates the heat inside the oven and cools the oven interior. After a certain period of time, the contact goes to the NC side and the power is turned off.

By doing this, the inside of the oven can be cooled down quickly after cooking in the oven, and the risk of getting burned by touching metal parts other than the door handle, which are quite hot due to heat conduction, can be prevented.

Especially when used as a microwave oven, the temperature inside the oven does not rise that much, and on the other hand, there is a risk of burns if you accidentally touch a metal part other than the door handle for a while after using it as an oven, so this cooling method is recommended. This is particularly effective in microwave ovens with heaters.

In addition, some oven dishes, such as cream puff pastries and sponge cakes, will not rise if the door is opened immediately after cooking, so please take these types of dishes into consideration and close the door once after cooking is complete. It is also possible to make the fan motor rotate after opening the door by inserting a switch linked to the door switch between the off contact and the power relay coil.

The above cooling uses a fan motor for cooling the magnetron, so there is no need for a new fan motor, and the cooling air from the magnetron can be kept inside the oven and used to prevent the door from fogging even when used as a microwave oven. When the oven is in use, the fan motor is turned off to maintain the internal temperature.

A simple changeover switch is sufficient to turn on the fan motor after using the oven.

[Brief explanation of the drawing]

The drawing is an electrical circuit diagram of a high-frequency heating device showing an embodiment of the present invention.

Claims (1)

[Scope of utility model registration request] A magnetron that supplies high frequency power into a heating chamber, a heater that heats the heating chamber, and a fan motor for cooling the magnetron, and a cooling air from the fan motor for cooling the magnetron is introduced into the heating chamber; It has a power relay that selectively operates the fan motor, with a first contact state that energizes the heater, a second contact state that energizes the power relay, and a state where neither the heater nor the power relay is energized. A high-frequency heating device comprising a spring timer having a third contact state, wherein the spring timer is configured to remain in the second contact state for a certain period of time after canceling the first contact state, and then return to the third contact state.