EP0110364B1

EP0110364B1 - Microwave oven with common wrap and cavity walls

Info

Publication number: EP0110364B1
Application number: EP83111895A
Authority: EP
Inventors: Ronald W. Millman
Original assignee: Litton Systems Inc
Current assignee: Northrop Grumman Guidance and Electronics Co Inc
Priority date: 1982-11-29
Filing date: 1983-11-28
Publication date: 1987-03-04
Also published as: DK543983D0; HK59488A; DK161481B; KR840007169A; IE54739B1; AU576741B2; DK161481C; ZA838604B; IE832658L; AU2145483A; ATE25799T1; DE110364T1; CA1203580A; DK543983A; DE3370118D1; EP0110364A1

Abstract

A low-cost microwave oven construction wherein a single sheet of metal forms both the cooking cavity and the outer wrap. The cavity, components compartment (12), and front and back panels (16, 17) are joined by a continuous crimped seam to form a unitary oven construction.

Description

This invention relates to the construction of microwave ovens and especially to the construction of the oven cavity and outer wrap.
Because of the need to contain microwave frequency energy in a controlled fashion, almost all microwave ovens heretofore known include a discrete, box-like element referred to as the cooking cavity, or simply cavity. The cavity was secured into some kind of frame which housed the remainder of the oven operating components, the entire assembly being enclosed in a decorative outer shell, called a wrap.
A microwave oven of the aforementioned kind is known from US-A-4 192 431. Due to the aforementioned structure, the oven is rather voluminous and its assembly is rather expensive.
Because of keen competition in the market place, it is necessary that microwave ovens be constructed as economically as possible. It is, therefore, the object of the present invention to provide a microwave oven which can be realised with substantial manufacturing economy and with comparatively reduced outer dimensions.
The present invention provides for the constructions of a microwave oven, having a combined oven cavity and wrap. A single formed metal sheet is folded to form an oven cavity which simultaneously provides one side wall and a major portion of the top and bottom walls of the outer wrap. A component section is added to the cavity to complete the other side wall and the remaining portion of the top and bottom of the wrap. A front and back panel are added to complete the construction. The cavity portion and the front and back panels are assembled by crimping techniques thereby eliminating the need for other forms of microwave tight sealing of the oven. Joining the ends of the first formed metal sheet along a crimped seam may provide a microwave tight sealing of the oven cavity against the components compartment.
The invention is further explained with reference to the accompanying drawings.

Brief description of the drawings

In the drawings, Figure 1 is an exploded perspective view showing the microwave oven construction of the present invention.

Figure 2 is a perspective view of the assembled oven.
Figure 3 is an enlarged partial cross section taken at line 3-3 of Figure 2 showing a portion of the crimp seam.
Figure 4 is an enlarged cross section of the crimp seam shown in Figure 3.

Description of preferred embodiments

Referring to the drawings, the oven cavity 10 is formed from a single flat metal sheet 1 which has been formed and folded to construct a generally box-like cavity. Hence the cavity 10 includes top wall 20, side wall 21, bottom wall 22 and side wall portions 23 and 24 each having flanges 18 and 19. After folding, side wall portions 23 and 24 are joined together along edge 26 by means of a crimp seam whereby the side wall portions are folded upon one another to form a secure folded seam of the type illustrated in Figures 3 and 4. An aperture 25 is provided in the side wall 24, over which is mounted a waveguide 15.
A components compartment 12 consisting of a generally U-shaped metal sheet (2) having an access portion and flanges 13 and 14 is attached to the cavity element 10 by spotwelding along the flanges 13 and 14.
Back panel 17 and front panel 16 are now added to the cavity/component compartment assembly. The front panel 16 is initially spotwelded to the flanges 18. The back panel 17 is initially spotwelded to the flanges 19. A crimp seam is then formed about the entire periphery of front panel 16 and back panel 17 crimping the front and back panels to the cavity element 10 and the component compartment 12. After the crimping operation the microwave oven structure is shown in Figure 2 results. The details of the crimp seam are shown in Figures 3 and 4.
After the electronic and other operating components of the microwave oven have been assembled in component compartment 12, an access panel (not shown) is placed over the component compartment 12 to close it. The access panel may be attached by means of tamper-proof fasteners. A microwave oven door (not shown) is then mounted to a front panel 16 to complete the oven construction.
The metal sheet 1 from which the cavity element 10 is formed can be finished and decorated as desired. Hence the exterior side of top wall 20 and side wall 21 may be painted some chosen color or may be covered with woodgrain vinyl. The interior side of the same top wall 20 and side wall 21, as well as bottom wall 22 may all be paintad a different color, such as white, for the interior of the oven cavity. However it is important to note that the oven cavity and outer wrap are both provided by the same single metal sheet and that there is no separate cavity and/or outer wrap portion. The exterior of component compartment 12 will of course be finished in the same manner as the exterior portion of the cavity element 10.
The construction described and illustrated provides for an extremely simple microwave oven construction comprising a very small number of individual parts. The use of the common cavity wall and outer wrap reduces the materials used in the oven and the construction complexity to a minimum, and the use of crimping techniques to assemble the components greatly reduces the labor required in assembly as compared to previously known constructions.

Claims

1. A combined microwave oven cavity and wrap comprising:

(a) a first formed metal sheet (1) folded into an open-ended box-like cavity (10);

(b) a second formed metal sheet (2) attached to one side wall of said cavity (10) to form a components compartment (12);

(c) a first panel (16) extending substantially across both said cavity (10) and said components compartment (12) forming an oven front, and,

(d) a second panel (17) extending substantially across both said cavity (10) and said components compartment (12) forming an oven back;

(e) said first and second panels (16, 17) being joined to said cavity (10) and said components compartment (12) along a continuous crimped seam to form a unitary assembly; whereby said first formed metal sheet (1) forms both the cavity interior walls (20-24) and portions of the outer oven wrap.

2. The structure of claim 1 wherein the ends of said first formed metal sheet (1) are joined along a crimped seam.