GB2212369A

GB2212369A - High-frequency energy cooking devices

Info

Publication number: GB2212369A
Application number: GB8726370A
Authority: GB
Inventors: Kenzo Okamoto; Fumihiko Kitada
Original assignee: IMARFLEX Manufacturing; Imanishi Kinzoku Kogyo KK
Current assignee: IMARFLEX Manufacturing; Imanishi Kinzoku Kogyo KK
Priority date: 1987-11-11
Filing date: 1987-11-11
Publication date: 1989-07-19
Also published as: GB8726370D0

Abstract

A high-frequency energy cooking device in which high-frequency electric waves are introduced from a high-frequency oscillating power source 7 via a waveguide 6 into a heating chamber through a power source opening 8 provided on an upper wall 5 of the heating chamber. A hemispherical part 11 protrudes from and is integral with a wall of the waveguide 6 at a position immediately above and opposite to the power source opening 8. <IMAGE>

Description

HIGH-FREQUENCY ENERGY COOKING DEVICES This invention relates to high-frequency energy cooking devices such as microwave ovens.

In previously-proposed microwave ovens, a dielectric part such as a post or stub is erected at a suitable position in the waveguide of a high-frequency energy cooking device. The dielectric part normally comprises aluminium or copper base materials. However, one disadvantage associated with these arrangements is high manufacturing cost, due to high material costs and the man-hours necessary for processing and assembling the arrangements.

According to the present invention there is provided a highfrequency energy cooking device in which high-frequency electric waves may be generated by a high-frequency oscillating power source and introduced into a heating chamber via a waveguide through a power source opening provided on a wall of the heating chamber, the cooking device including a hemispherical dielectric part protruding from and integral with a wall of the waveguide at a position aligned with and opposite to the power source opening.

A preferred embodiment of the invention, to be described in greater detail hereinafter, provides a high-frequency energy cooking device equipped with an improved waveguide at a lower cost without using expensive materials as previously-proposed, and with a significant simplification of the construction and the assembling process.

The protrusion height and diameter of the hemispherical dielectric part are preferably one half of the respective height and width of the waveguide.

The preferred dielectric part gives directivity to microwaves generated in the high-frequency oscillating power source and transmits the microwave energy into the heating chamber from the power source opening provided in an upper wall of the heating chamber.

The invention will now be described by way of example with reference to the accompanying drawings, throughout which like parts are referred to by like references, and in which: Figure 1 is a perspective view of major parts of a high frequency heating device according to an embodiment of the present invention; Figure 2 is a longitudinal sectional view of a waveguide of the heating device shown in Figure 1 Figure 3 is a section along a line Ill-Ill of Figure 2; and Figure 4 is a plan view of the waveguide of Figures 2 and 3.

Figure 1 is a perspective view showing major parts exposed after removing an outer cover of a high-frequency energy cooking device embodying the present invention. A backplate 2 is mounted to the rear part of a main body 1. A front frame 3 is provided at the front of the main body 1, the front frame 3 being capable of supporting a door (not illustrated in the figure) in a freely openable and closable manner, for example by means of a hinge.

A heating cooking box or compartment 4 is provided in the interior of the main body 1 for housing an object to be cooked.

A waveguide 6, comprising an elongate rectangular box manufactured by pressing sheet metal, is installed on an upper wall 5 of the cooking compartment 4.

A high-frequency oscillating power source, such as a magnetron 7, is provided at the right-hand end (as shown in the drawing) of the waveguide 6. In addition, a power source opening 8 (Figures 2 to 4) is provided in the left-hand interior part of the waveguide 6 on the cooking compartment 4, namely the upper wall 5 of the heating chamber, for introducing oscillating electric microwave energy into the heating chamber from the magnetron 7.

Figure 2 shows a central longitudinal sectional view of the waveguide 6. The upper right-hand end of the waveguide 6 is located at an oscillating antenna 10 of the magnetron 7, while its left-hand end is extended to a position where the power source opening 8 provided in the upper wall 5 of the cooking compartment 4 is aligned with the left-hand end. The power source opening 8 is, distributedly located at three positions shown by chain lines in Figure 4.

Each part of the power source opening 8 is cut and bent by a press while forming each cut piece angled towards the interior of the waveguide 6 at a suitable angle, so as to form a respective reflective plate 9.

Thus the size of the power source opening 8 is related to the size of each reflecting plate 9.

A hemispherical dielectric part 11 is pressed out protrudingly from and integral with the waveguide 6 at a position in the upper wall of the waveguide 6 which is opposite the centre of the power source opening 8 located at the three positions, namely at tne intersection of lines X-X' and Y-Y'. Accordingly, a protruding part of the dielectric part 11 is simultaneously and very easily constructed by pressing an elongate rectangular box type waveguide by means of a drawing process.

It is preferred that the height of the protruding part should be one half of the total height of the waveguide 6 and that the diameter of the protruding part should be one half of the width of the waveguide. As a result, the dielectric part n1 can give a directivity to generated electric waves while irradiating microwave energy to an object located in the cooking compartment 4, for cooking the object without leaking energy to the outside.

According to the arrangement described above, a hemispherical protruding part, namely the dielectric part 11, may be constructed simultaneously when the waveguide 6 is pressed from sheet metal into a box form. Therefore, there is a reduction in the raw materials required while machining processes are shortened compared to a previously-proposed processing method in which members forming the dielectric part, separate from the component material of the waveguide, are screwed, welded or crimped on to the waveguide. Thus, embodiments of the present invention can provide a low-cost highfrequency energy cooking device.

Claims

CLAIMS 1. A high-frequency energy cooking device in which high-frequency electric waves may be generated by a high-frequency oscillating ower source and introduced into a heating cnamber via a waveguce tnrougr a power source opening provided on a wall of the heating chamber, the cooking device including a hemispherical dielectric part protruding from and integral with a wall of the waveguide at a position aligned with and opposite to the power source opening.
2. A cooking device according to claim 5, wherein the height of the hemispherical dielectric part protruding from and integral with the wall of the waveguide is one half of the height of the waveguide.
3. A cooking device according to claim 1 or claim 2, wherein the diameter of the hemispherical dielectric part protruding from and integral with the wall of the waveguide is one half of the width of the waveguide.
4. A high-frequency energy cooking evi substantially as hereinbefore described with reference to tne accompanying drawings.