GB2200019A - Micro-wave oven with readily removable magnetron - Google Patents

Abstract

A micro-wave oven, has a thermal heating device with an oven muffle (18), a magnetron (9), a waveguide (27) rigidly connected to the oven muffle, and an electronic housing (7) in which the electronic power system and a fan (11) are accommodated. The magnetron is pluggably connectable to the waveguide (27) so that the electronic housing (7) and its contents can easily be removed to facilitate repair and maintenance. <IMAGE>

Description

MICRO-WAVE OVEN The invention relates to a micro-wave oven, particularly an oven with a thermal heating device, an oven muffle, a magnetron, a hollow conductor rigidly connected to the oven muffle and serving as a channel for the micro-waves, and an electronic housing in which the electronic power system and a fan are accommodated.

German Patent 2947954 shows a micro-wave oven in which, above the muffle housing and at a distance therefrom, a housing is provided which has components functionally belonging to a magnetron, such as a high-frequency transformer and a capacitor, as well as a cooling fan. The magnetron is rigidly connected to the micro-wave channel or hollow conductor leading into the interior of the muffle and only extends into the aforementioned housing via an aperture, being merely sealed in addition but without being held by the housing.This system suffers from the drawback that although the housing is separable from the remainder of the oven this does not apply to the magnetron, which is rigidly connected thereto, so that in the event of a fault the entire micro-wave oven has to be sent in for repair, while the breakdown of the magnetron necessitates the expensive operation of separating it from the rest of the baking oven.

A further drawback resides in the need to manipulate the whole of the baking oven when repairs are required.

Excessive space is also required to accommodate it, and it makes particularly heavy demands on the space accessible from the front of a fitted unit in a fitted kitchen, while there is usually sufficient space available behind such micro-wave ovens, owing to their limited depth by comparison with the dimensions of fitted kitchens in this direction.

German Unexamined Specification 2825N61 shows a micro-wave oven as part of a double baking oven, in which the magnetron and a fan ar-e mounted above the micro-wave oven, in the common housing of the two baking ovens. Here again considerable loss of space in an unfavourable position is involved. In German Unexamined Specification 3104677 the magnetron is positioned above the muffle and the rest of the electronic system behind the latter, the two zones having separate ventilation systems. Apart from the considerable wastage of space, again in unfavourable positions, this system likewise is disadvantageous from the point of view of repair and maintenance.

An object of one aspect of the present invention is to provide a micro-wave oven in which the functional components, particularly the electronic power system, will be arranged in a space-saving manner and so as to facilitate repair and maintenance operations.

-Accordingly the present invention provides a microwave oven comprising a thermal heating device, an oven muffle, a magnetron, a hollow conductor rigidly connected to the oven muffle and serving as a channel for micro-waves, and an electronic housing in which an electronic power system and a fan are accommodated, and in which the magnetron is built into the electronic housing and is pluggably connectable to the hollow conductor via a micro-wave outlet so that the electronic housing including the magnetron can be easily detached from the remainder of the oven.

The design of the micro-wave oven according to this aspect of the invention makes it possible for the electronic housing, with the parts present therein, to be completely removed from the rest of the micro-wave oven and replaced without any excessive expense or labour, by simply moving the housing with the magnetron away from the hollow conductor.

The repair can then be effected without having to manipulate the whole of the heavy micro-wave oven. A replacemeht housing likewise having all the electronic power parts can then be connected to the hollow conductor. The only additional operations which may be involved are those of tightening up certain screws by which the housing is secured to the remainder of the micro-wave oven and providing the necessary electrical connections, e.g. from the electronic housing to the connections for tubular heating elements in the case of a micro-wave oven with supplementary thermal heating.

In other aspects the invention extends to novel positioning of the various units relative to one another and novel arrangement of the ventilation/cooling system.

For the ventilation of the muffle of the micro-wave oven a particularly advantageous version has a guide channel provided at an outlet of the fan provided in the electronic housing and leading to an inlet aperture of the muffle, the said guide channel being partly defined by a curved baffle plate. Between the aperture by which the cooling air emerges from the electronic housing and any guide channel formed by a baffle plate and leading to the inlet aperture for the muffle there are no additional fixed connections.

When the electronic housing is mounted through the micro-wave outlet of the magnetron onto the hollow conductor rigidly connected to the muffle the outlet aperture of the fan is simply attached to the further air guide channel.

A further preferred development of the invention provides that the electronic housing has air inlets and that the fan takes in air by suction from the interior of the housing, while the zone towards which the air inlets of the electronic housing open is connected to an air inlet slit on the front of the micro-wave oven and, in particular, the electronic housing is situated at a certain distance from a base plate of the said oven. In the case of a built-in oven the air is mainly taken in by suction from the front of the oven and also re-expelled to this part.The aforementioned apparatus according to the invention provides a simple constructional means of achieving this object and at the same time ensures that all parts of the electronic power system, such as the transformers, capacitors and fan motor, together with any stirrer which may be provided in the housing, will be cooled by the air suckedtin by the fan, first of all into the electronic housing, so that overheating is avoided. The air guide channel from the air inlet slit in the front of the micro-wave oven is thermally insulated from the muffle, thanks to the fact that the latter is surrounded by heatinsulation material, such as mineral fibre plates or the like.A further development provides that the micro-wave oven has a recess at the rear, that the electronic housing and the recess are adapted to each other, that the electronic housing is inserted in the recess and, in particular, the cover of the micro-wave oven is provided, in a zone situated opposite to an aperture of the hollow conductor, for the connection of the micro-wave outlet of the magnetron, with a cut-out, so that the electronic housing can be plugged in or removed in alignment with the axis of the aperture of the micro-wave channel.This ensures that the electronic power system compactly accommodated in the electronic housing can be situated in a position on the micro-wave oven which, thanks to the fact that the depth of the oven muffle does not amount to the full depth of a built-in kitchen strip, is left free and cannot be used for other purposes, thus avoiding zones above or below the muffle, which are accessible from the front of the built-in kitchen strip and capable of being utilized as a storage surface, being occupied by electronic power parts of the-micro-wave oven.

Altogether the design of the micro-wave oven offers the advantage that the entire electronic power part can be manufactured and assembled separately from the micro-wave oven itself, so that it only has to be connected as a unit, in a simple and convenient manner, to the remainder of the micro-wave oven, which contains the muffle. This construction, moreover, renders the micro-wave oven easy-.to repair and maintain.

Further advantages and characteristics of the invention will emerge from the claims and from the following description, in which an example of micro-wave oven is explained in detail by reference to the drawing. The diagrams are as follows: Fig. 1: a front view, in perspective, of a micro wave oven omitting the door of the oven muffle; Fig. 2: a rear view, in perspective, of the oven with the rear cover removed.

The micro-wave oven is provided with a base plate 2 which covers practically the whole of its base surface. The base plate 2 has an upwardly projecting edge 3 extending around the side and rear. With the edge 3 is connected a hood 4, covering almost the entire micro-wave oven and preferably made of a metal sheet.- The hood 4 has a rear recess 6 in which is mounted the electronic housing 7 which contains a magnetron 9, a transformer 8, a fan 11 and other electronic parts 12 and 13 such as capacitors etc. Angle bars 17 contributing to the reinforcement of the hood 4 are affixed to the front edges of the side cheeks 16 of the hood 4. The door (omitted from the drawing) is affixed to one of the angle bars 17. The muffle 18 is situated in the housing consisting of the base 2 and the hood 4. Underneath the front side of the muffle 18 is a shutter 19 with an operator's panel 21.The shutter 19 is not covered by the door (not shown). Between the lower edge 22 of the muffle 18 and the shutter 19 is provided a cooling air inlet slit 23 which, communicates via the space under the muffle with the space 24 (Fig. 2) in the rear zone of the baking oven 1.

The electronic housing 7 is situated on the edge 3 of the base plate 2 and is thus raised by a certain distance from its base surface. It is provided, in the lower zone, in the vicinity of the transformer 8, with a row of perforations 26.

Underneath the muffle 18 a hollow conductor 27, serving as a micro-wave channel, extends towards the rear, starting from approximately the middle of the said muffle. The micro-wave channel has an aperture at the top of its rear zone extending over the muffle 18. In the zone of the projecting portion of the hollow conductor 27 the electronic housing is provided with an off-set part so that, when that zone of the base of the electronic housing 7 which is provided with the perforations 26 is resting on the edge, that zone of the electronic housing 7 which is situated over the end of the hollow conductor 27 will rest on this latter. The magnetron 9 is positioned in the zone mentioned.Underneath the magnetron 9 a pipe connection extends from the base of the electronic housing 7 into the aforementioned aperture of the hollow conductor 27, so that the magnetron 9 can be connected to the hollow conductor 27 by simply plugging it in, thus producing the micro-wave connection. The pipe connection has a certain amount of play in the hollow conductor, so that thermal expansions can be absorbed.

In addition, the electronic housing 7 can be secured on the base 2 or the hood 4 by a small number of further screws or other fasteners.

The fan 11 is a radial fan which takes in air by suction in an axial direction from the interior of the electronic housing 7, re-expelling it via a channel 31 connected to its periphery. The channel 31 is connected by the magnetron to an outlet 32 in a lateral wall of the electronic housing 7. Underneath the outlet 32, in the rear zone of the micro-wave oven 1, is a baffle plate 33 with which the air is conveyed to an aperture 34 at the rear of the muffle 18 and via the said aperture into the muffle 18.

The top of the muffle 18 itself is provided with ventilation apertures which communicate with an air vent slit 36 provided in the front upper zone above the muffle aperture.

Accordingly, the fan 11 takes in air by suction via the front inlet slit 23, the air passing under and past the muffle 18 into the space 24 and from there via the perforations 26 into the electronic housing 7, where it can sweep and cool the electronic elements before it is conveyed through the fan into the channel 31 and via the said channel and through the magnetron 9 in order to cool the latter.

The air then emerges from the aperture 32 and is conveyed via the baffle plate 33 around and through the aperture 34 into the muffle 18, from which it re-emerges to the outside via the aforementioned apertures in the top and via the air vent slit 36.

Underneath- the muffle 18, in the outlet zone of the hollow conductor 27, a so called stirrer may be provided of which a shaft passes through the micro-wave channel and which is provided at its lower end with a disc which has a peripheral groove and via which it can be driven by means of a motor situated in the electronic housing 7.

In the event of break-downs in any electronic element in the electronic housing 7, as a result of the fai-lure of the element or other causes, the electronic housing 7 can be detached, after releasing the said fasteners from the rest of the micro-wave oven 1, by simply lifting it off, after which the connecting socket belonging to the magnetron 9 and extending into the aperture of the hollow conductor 27 is drawn out of the channel 27. A substitute electronic housing with the same elements can be mounted, while the original housing 7 is sent in for the relevant electonic parts to be repaired. It is also possible, after the electronic housing 7 has been separated from the rest of the micro-wave oven, for parts which have broken down or suffered damage to be immediately replaced or repaired more easily and conveniently on the spot, since the electronic housing is far easier to handle than the complete micro-wave oven 1. The micro-wave oven described is thus rendered far easier to repair and maintain than those covered by the prior art.

Claims (10)

1. A micro-wave oven comprising a thermal heating device, an oven muffl 'L device, an oven muffle, a magnetron, a hollow conductor rigidly connected to the oven muffle and serving as a channel for micro-waves, and an electronic housing! in which an electronic power system and a fan are accommodated, and in which the magnetron is built into the electronic housing and is pluggably connectable to the hollow conductor via a microwave outlet so that the electronic housing including the magnetron can be easily detached from the remainder of the oven.

2. A micro-wave oven in accordance with Claim 1 in which an air guide channel leading to an inlet aperture of the muffle is connected up to an outlet of the fan.

3. A micro-wave oven in accordance with Claim 2, in which the air guide channel is partly defined by a curved baffle plate.

4. A micro-wave oven in accordance with any of the foregoing claims, in which the electronic housing is provided with air inlets, particularly in the form of perforations, and the fan takes in air by suction from the interior of the housing.

5. A micro-wave oven in accordance with Claim 4, in which the space to which the air inlets of the electronic housing open is connected with a cooling air inlet slit at the front of the micro-wave oven.

6. A micro-wave oven in accordance with Claim 4 or Claim 5, in which the electronic housing is spaced from a base plate of the micro-wave oven.

7. A micro-wave oven in accordance with any of the foregoing claims, in which the electronic housing is affixed by means of a small number of fasteners to a housing of the remainder of the micro-wave oven 1.

8. A micro-wave oven in accordance with any of the foregoing claims in which the oven, apart from the electronic housing, has a housing provided at its rear with a recess 6, and in which the electronic housing and the recess are shaped to fit together with the electronic housing inserted into the recess.

9. A micro-wave oven in accordance with any of the foregoing claims, in which a cover of the miocro-wave oven is provided, in a zone situated opposite to an aperture of the hollow conductor, for the connection of the micro-wave outlet of the magnetron, with a cut-out, so that the electronic housing can be inserted or removed in alignment with the axis of the aperture of the micro-wave channel.

10. A micro-wave oven substantially as described herein with reference to or as illustrated in the accompanying drawings.