NL8102279A - HIGH-FREQUENCY HEATING DEVICE. - Google Patents

Description

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Title: high-frequency heating device.

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The invention relates to and aims to provide a simple and effective way of preventing heat and high-frequency radiation from the space between a door and a heating chamber of a high-frequency heating device provided with an electric heating element, leaking.

. In the known combinations of electric heating element and high-frequency heating device and more particularly when applying it to self-cleaning devices, it is necessary to keep the interior of a heating chamber at a temperature TO of about 500 ° C during cleaning. . A seal consisting of woven glass fibers is used to prevent heat from leaking between a door and a front wall of the chamber during operation. However, in the case where such a dielectric component as the glass fiber seal between the front wall of the chamber and the door is fitted, the thickness of the dielectric member is 3 - mm or more, so that a large amount of high-frequency radiation can leak out. Several attempts have been made to provide a solution to this problem.

Thus, (a) a seal consisting of glass fibers surrounded by metal wires or strips, and (b) a seal of woven glass fibers coated with a net of metal wires have already been proposed and used.

However, the first method (a) has the following drawbacks. When the metal wires are wrapped around the glass fibers and. woven into the seal 25, the metal wires themselves tend to sink into the glass fibers due to the mechanical tensile stress because the metal wires are thin and stiff, but the glass fibers soft. There are no metal wires on the surface of the seal. By increasing the number of metal wires or using metal strips, a small number of metal parts are present on the surface, however. it has been found that no satisfactory results are hereby obtained in shielding high-frequency radiation. The seal as a whole becomes relatively stiff and slightly flexible, so that the seal is difficult to bend to conform to the surface of the door.

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If the thickness of the seal is more than 10 mm and the seal is very flexible, it is possible in the above-mentioned second method (b) to shield to some extent heat and gases released during the self-cleaning. Since a throttling device as a means for sealing high-frequency radiation usually does not allow the seal to be thick enough, the seal per se is less flexible, so that there is a high probability that heat and gases will leak out easily even when the seal is covered with the metal net.

10 In view of the above, the following requirements are imposed on the seal: (1) the seal must be very flexible, (2) the mesh of the seal must be sufficiently fine to retain gases and heat, (3) the surface of the seal must be electrically conductive, (k) the seal must be soft and be able to bend appropriately to the door 15, etc.

In view of the above, the object of the invention is to provide a simple seal, wherein the problems of the known seals do not arise and which seal meets the above requirements.

The invention will be explained in more detail below with reference to the drawing. In the drawing: Fig. 1 shows a perspective view of an embodiment of a heating frequency heating device according to the invention; fig. 2 shows a vertical cross section of the device; and Figures 3 and k are enlarged cross-sections of an important part of the device.

The in fig. The heating device shown is of the built-in type, on the top of which four electric burners 1 are present for cooking purposes. The electric burners 1 can be controlled by knobs 2 mounted on a front panel of the heating device, on which panel are also arranged control knobs 3 for operating the heating device.

Ventilation openings U for cooling air are located under the control panel and above a door 6 with a handle 5. Under the heating device body 35 is a drawer J for receiving additional parts and other small items.

As can be seen from Fig. 2, the door 6 is of the sliding type 81 0 2 2 7 9 τ ~ - 3 - and the door can slide on a rail 8. The door é is provided on the inside thereof with a plateau 9 on which food or the like can be placed.

It is highly preferred to apply and remove the food if the tray 9 is moved outward when the door 6 is opened. The heating chamber 10 includes an upper heating element 11, which extends substantially parallel to the top wall of the chamber, and a lower heating element 11f at the outer bottom wall of the chamber for heating food.

Behind the chamber 10, a hot air circulation fan 12 is arranged to equalize the temperature distribution in the chamber. A heat insulator 13 is located on the outlet of the chamber 10 'to prevent heat from escaping from the outer walls of the chamber and to ensure higher efficiency. A high-frequency oscillator 14 or a microwave oven supplies high-frequency energy via a Z-shaped waveguide 15, one end of which is connected to one. supply opening i, which is substantially in the center of the top wall of. chamber 10 is formed. A rotatable antenna 17 extends through the opening 16 ', which directs high-frequency energy via the waveguide to the interior of the room.

A cooling fan 32 for the microwave oven 14 must supply and extract air via an air line 33 and the ventilation openings k.

A throttling member 18 "with a groove, the depth of which is equal to a quarter wavelength of the high-frequency radiation used here, is attached to the door 6 to prevent leakage of high-frequency radiation.

Outside of the throttling device is a seal "19 to shield heat and high frequency radiation from the interior of the chamber, this seal consisting of a woven blend 21 of glass fibers 20 and fibrous stainless steel of appropriate ratio, such as the best It can be seen from Fig. U. Since the two components are fibrous, the mixture does not become rigid and does not lose its flexibility even when the stainless steel content is increased, so the mixture can be easily processed. when attached to the door and is very effective at shielding heat. In addition, since the metal does not penetrate the fiberglass material, only a small amount of 8102279 bm stainless steel ensures good surface conductivity while providing particularly good protection of the high-frequency energy.

In the event that wires, hands or the like are used to obtain a comparable shield, a large amount of material is required with correspondingly higher cost. The invention, on the other hand, provides an inexpensive, but particularly good, high-frequency shielding. In addition, in the case of wires and the like, these can be deformed or broken with minimal durability with repeated opening and closing of the door. However, in the case of the fibrous stainless steel, the seal exhibits stable operation over the entire service life of the device without the danger associated with threads.

As already mentioned, the invention provides a seal with the following advantages: simple construction, particularly good heat e-15 and high frequency shielding, easy manipulation, easy to process, low cost, high durability and high reliability.

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Claims (1)

5 .-- · C o n c 1 u s i e. Combined sealing against thermal and high-frequency radiation, more particularly for sealing gaps present between baking oven doors and baking oven chambers of a high-frequency device, in the form of an elastic insert, characterized by a mixed braid (21) of heat-resistant fibers (20) of a dieletrically heat-conductive material, such as glass fibers or the like, and fibrous metal wires of a non-corroding material, such as stainless steel. 8102279