JPH0124357B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a high-frequency heating device that uses an antenna such as a rotating antenna to supply high-frequency energy into a heating chamber. This prevents problems such as sparks and decreased output caused by the sealing plate becoming dirty.

Generally, the electric field near the coupling hole in the heating chamber is very high, and when the reflection coefficient is high, such as during light loads, sparks may occur between the coupling hole in the heating chamber and the antenna. When the seal is sealed with a dielectric material, electric lines of force tend to concentrate on this dielectric portion, so sparks are extremely likely to occur, especially when the surface of the seal portion is contaminated with food scraps, oil, etc. In order to prevent this problem, the shape of the sealing part has been proposed in the past to make the creepage distance between the antenna and the end face of the heating chamber coupling hole as large as possible, but if the sealing plate becomes extremely dirty, the creepage distance must be made slightly larger. Even if you do so, it is not possible to completely prevent sparks.
In particular, in high-frequency heating devices that use a heater in combination, the oil that is scattered during cooking becomes carbonized by the heat of the heater and sticks to the surface, so if you neglect cleaning the heating chamber a little, it becomes very easy to spark. Furthermore, if the surface of the sealing plate becomes contaminated with carbide, the operating point of the magnetron may change, causing problems such as a decrease in output. Therefore, the present invention has a structure in which a contamination prevention plate for the sealing plate is installed concentrically with the antenna directly under the sealing plate, so that oil etc. splashed from food do not contaminate the sealing plate, thereby causing problems such as sparks and reduced output. This completely prevents

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

The heating cooker shown in FIG. 1 is a built-in type built into a sink, and four electric stoves 1 are arranged on the top surface of the cooker for cooking boiled food. The electric stove 1 is controlled by a knob 2 provided on the front panel of the cooking device, and a control knob 3 of the cooking device is arranged on the same panel. Reference numeral 4 denotes a cooling intake/exhaust hole located above a door 6 having a handle 5 at the bottom of the control panel. Reference numeral 7 designates a drawer provided below the main body of the cooker for storing small items such as attachments.

Next, in FIG. 2, the door 6 is of a pull-out type that slides on a rail 8, and a shelf 9 is provided on the inner surface of the door 6 on which foods and the like can be placed.

Therefore, when the door 6 is pulled out, the shelf 9 comes out, making it easy to take food in and out, and is convenient to use. 1
Reference numeral 0 denotes a heating chamber in which food is cooked, and an upper heater 11 is provided above the heating chamber substantially parallel to the upper wall of the heating chamber, and a lower heater 11' is provided on the outer bottom wall of the heating chamber.

Reference numeral 12 denotes a fan for circulating hot air provided at the rear of the heating chamber 10, which makes the temperature distribution within the heating chamber uniform. Reference numeral 13 denotes a heat insulating material provided around the outer periphery of the heating chamber 10, which prevents heat dissipation from the outer wall of the heating chamber and improves thermal efficiency. 14 is a magnetron which is a high frequency oscillator, and has a configuration in which high frequency energy is transmitted through a Z-shaped waveguide 15, and one end of the waveguide 15 is connected to a coupling port provided approximately in the center of the upper wall of the heating chamber 10. 16. The connection port 16 has an L
A rotary antenna 17 is rotatably provided through the antenna, and the rotary antenna 17 is composed of a vertical portion 18 and a horizontal portion 19. The above antenna 17
One end of the vertical portion 18 is fixed within the waveguide 15 to an antenna drive shaft 20 made of a low-loss dielectric such as alumina porcelain, and this antenna drive shaft 20 penetrates the upper wall of the waveguide 15. Rotating axis 2
1 and a matsuba pin 22, and the rotating shaft 21 is a thrust bearing plate 23 fixed to the outer wall of the waveguide 15.
The drive source is the motor 24, and the motor shaft 2
5 and a pin 26.

Therefore, even if the centers of the motor shaft 25 and the rotary antenna 17 are slightly misaligned, they rotate smoothly.

A sealing plate 27 seals the coupling port 16 and is made of a low-loss dielectric to prevent hot air in the heating chamber 10 from passing through the waveguide 15 to the magnetron 14 . Therefore, the rotating antenna 17
rotates using the sealing plate 27 and the upper wall of the waveguide 15 as bearings.

A contamination prevention plate 28 of the sealing plate is attached to a portion of the vertical portion 18 of the rotary antenna on the heating chamber side, facing the sealing plate 27. This is because oil etc. splashed from the food changes on the sealing plate, creating a situation similar to a short circuit between the antenna and the heating chamber through this surface, causing problems such as sparks and decreased output. This is to prevent this from happening.

Since the stain prevention plate 28 has a diameter smaller than the sealing plate, the outer circumference of the sealing plate may become dirty.
In short, there is no need to make the diameter of the contamination prevention plate larger than the diameter of the sealing plate since it is sufficient that there is a completely clean insulating layer between the antenna and the end of the heating power supply port.

Furthermore, since the operating point of the magnetron changes by changing the diameter of the dirt prevention plate, it is also possible to adjust the operating point to an optimum state by changing the dimension of this diameter.

If the purpose is simply to prevent the sealing plate from getting dirty, the dirt prevention plate can be attached to the heating chamber side instead of the antenna side as in this example, but in that case, the dirt prevention plate can be attached to the outer conductor of the coaxial line. In order to perform the same function as the anti-fouling plate, the high frequency loss between the antenna and the dirt prevention plate increases and the effective length of the antenna inside the oven changes, so it is necessary to further increase the length of the vertical part of the antenna. A major disadvantage arises in that the effective usable height within the heating chamber is reduced.

As explained above, according to the present invention, by making the structure simple and completely preventing the sealing plate from becoming dirty,
It has very great effects, such as preventing problems such as sparks and output reduction, and at the same time can be used to adjust the operating point by changing the dimensions of the dirt prevention plate.
Furthermore, problems that may occur when trying to obtain the same effect with other dimensions are also solved, making it practical and highly effective.

In the above configuration, radio waves from the magnetron 14 pass through a Z-shaped waveguide 15 and are radiated into the heating chamber 10 from a rotating antenna 17 that is rotationally driven by a motor 24 . The cooling air for the magnetron 14 enters through the intake and exhaust holes 4, cools the magnetron 14 by the cooling fan 32, and is discharged to the front through the intake and exhaust holes 4.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a high-frequency heating device showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the same, and FIG. 3 is an enlarged sectional view of the same essential parts. 10... Heating chamber, 14... Magnetron, 15
... waveguide, 16 ... coupling hole, 17 ... antenna, 28 ... dirt prevention plate, 27 ... sealing plate.

Claims (1)

[Claims] 1. A heating chamber, a high-frequency oscillator, a waveguide that transmits the high-frequency energy oscillated by the high-frequency oscillator to the heating chamber, an antenna that couples the waveguide and the heating chamber in a high-frequency manner, and A sealing plate made of a dielectric material that closes a coupling hole with the antenna provided in the wave tube and the heating chamber, and the antenna has a dirt prevention plate of the sealing plate at a position opposite to the sealing plate. A high-frequency heating device characterized by: