Microwave oven with internal ventilation

p0001The present invention relates to a recessed microwave oven with internal ventilation comprising an outer enclosure for insertion in a recess located in a kitchen cabinet.

p0002Specifically, the invention proposes to carry out the internal ventilation of the enclosure, areas to ventilate in this chamber being of two types: the areas to be cooled on the one hand and the areas to be reclaimed on the other. The areas to be cooled are all electrical or electronic components which, by Joule effect, give off heat. Areas to dry are those which are present inside the cooking cavity, or, especially, the door and the walls of the cavity on which the water vapor emitted during the heating of food by micro oven, tends to condense.

p0003It is necessary to provide a circulation of air inside the oven, as well as, of course, input and output of the air orifices.

p0004known microwave ovens have, for many of them, at least one of these orifices located on a face other than the front face. This requires to make a recess providing a natural circulation of air space and to bring the air inlets and outlets in the facade plane front of the oven or to provide for a chimney on the back; Recessed. Demand for<patcit id="pcit0001" dnum="US4332993A"><text>patent US4332993</text></patcit> on the other hand discloses a device which is positioned on the inlet and air outlet arranged on the top of the oven and which, by the presence of a turbine, ensures the inlet and the outlet of air in the speaker said furnace.

p0005Such systems exhibit all the following constraint: there must be an installation niche dimensions greater than the overall dimensions of the unit.

p0006A common constraint of these devices, especially if we want a niche to the smallest possible dimensions, is the necessary presence of a ventilation chimney in the kitchen cabinet.

p0007There is also known a cooking microwave oven disclosed in <patcit id="pcit0002" dnum="DE3104677A1"><text>DE 31 04 677 A1</text></patcit>. This document describes a microwave cooking oven comprising a cooling device divided into at least two individual areas which each space has a separate air circulation.

p0008However, this baking furnace has the disadvantage of being provided with a cooling device has two hot air discharge openings and wet located in the upper part and at the rear of the oven so as to suppress two flows hot, humid air in a chimney formed in the niche housing the cooking microwave oven.

p0009The object of the invention to provide a built microwave oven imposing no constraint on the niche for receiving, it simply presenting the standard sizes offered by the kitchen furniture manufacturers. The invention thus facilitates the integration of said furnace in a kitchen. The invention proposes, moreover, to do so economically.

p0010According to the invention, the air circuit inside the microwave oven is as follows: The air enters through the air inlet located in the upper area of ​​the front of the oven, above the door , it passes through a first technical area being drawn by the fan, before being divided into two streams at the outlet of the fan. The first flows through a second technique area and will dry the door and inside the cooking cavity before joining a fourth technical area. The second stream through a third technical area before joining the fourth technical area. The two streams meet in the technical area before exiting the oven through the openings positioned in the lower part of the front of the oven, beneath the door.

p0011And ventilating the entire interior of the oven is ensured.

p0012Can be seen a first technical area, where is placed the control electronics and, ideally, the power electronics. According to the invention, this area between the air inlet and fan, a slight depression and bathed by the fresh air arriving from the atmosphere of the room.

p0013The magnetron, placed according to a preferred feature of the invention, in the second technical area, is cooled by heating the flux through it before being introduced into the cooking cavity, allowing the heated air to increase its capacity drying of the cooking cavity and to heat the door and walls of said cavity to prevent condensation.

p0014Finally, the power to the magnetron, ideally located in a third zone technique and preferably in the lower part of this zone is cooled by the third stream, while being advantageously positioned in the lower part of the furnace. This positioning in the lower part facilitates the design of the apparatus, said power supply being a high mass member, and thus binding to the structure.

p0015In addition, an interesting consequence of this device is that it enables use of an economic fan comprising a single engine driving two turbines.

p0016According to a particularly interesting characteristic of the invention, the steam escaping from the heated food and has a natural tendency to rise once it is no longer imposed in a circuit, leaves the lower end from the oven. So it has time to become diluted in the air before risking deposit on the wall of the unit immediately above the oven. This preserves the aesthetic and functional qualities of that furniture.

p0017In a preferred embodiment of the invention, the output of the first stream which has passed through the cooking cavity takes place in the upper part thereof. This stream then goes down by a fifth technical area between the side walls of the enclosure and the cavity before returning to the second stream in the fourth technical area. This gives him time to cool before being expelled to the outside of the oven.

p0018Other features and advantages of the invention emerge from the description which follows, given by way of nonlimiting example, with reference to the accompanying drawings in which:<ul><li>The <figref idrefs="f0001">figure 1</figref> is a perspective view of a microwave oven according to the invention; </li><li>The <figref idrefs="f0002">2</figref> is a view similar to that of <figref idrefs="f0001">figure 1</figref> and illustrates especially the zone 4a and the way the air flows in said zone;</li><li>The <figref idrefs="f0003">3</figref> is a view similar to that of <figref idrefs="f0001">figure 1</figref> and illustrates especially the zone 4b and how the air flows in said zone;</li><li>The <figref idrefs="f0004">4</figref> is a view similar to that of <figref idrefs="f0001">figure 1</figref> and illustrates especially the area 4c and how the air flows in said zone;</li><li>The <figref idrefs="f0005">5</figref> is a view similar to that of <figref idrefs="f0001">figure 1</figref> and illustrates especially the zone 4d and the way the air flows in said zone; and</li><li>The <figref idrefs="f0006">6</figref> is a view similar to that of <figref idrefs="f0001">figure 1</figref> and more specifically illustrates the fourth area and how the air flows in said area.</li></ul>

p0019To the <figref idrefs="f0001">figure 1</figref> shows a perspective view of a microwave oven according to the invention. This view allows, in particular, to visualize the various components that will occur in the following description. Of course, many components such as those participating in the drive of the oven tray or to its illumination are not shown or described here as they do not different from the well known devices to those skilled in the art and available on present ovens.

p0020The <figref idrefs="f0001">figures 1</figref> and <figref idrefs="f0002">2</figref> illustrate the airflow in the technical area 4a.

p0021According to the invention, thanks to the suction fan 11, the air enters the zone 4a through the openings 5 ​​located in front of the oven, between the front door 3 and the control panel 8. It cools the electronic components 7 which are located behind the control panel and / or at other locations within said area 4a. Then it enters one of the two turbines 11b or 11c of the fan, said turbine being both rotated by the motor 11a.

p0022Thus, according to the invention, the technical area 4a is depressed through the suction provided by the fan 11.

p0023The fact that the fan 11 is formed of a motor 11a and two turbines 11b and 11c is very advantageous from an economic standpoint. However it can be envisaged to replace it with two fans to a single turbine within the scope of the invention.

p0024The <figref idrefs="f0001">figures 1</figref> and <figref idrefs="f0003">3</figref> illustrate the airflow in the technical area 4b.

p0025According to the invention, the technical area 4b is formed of a first air guide 12, the magnetron 9 and a second air guide 13. This technique zone 4b is washed by the stream b from turbine 11b . The first air guide 12 directs the flow of pressure to the magnetron 9. As an indication, within the air guide 12, air is at a temperature in the range of 35 to 55 ° C and preferably equal to 45 ° C. Said magnetron 9 is crossed and thereby cooled by the stream b. The stream b is then directed to the front of the oven through the air guide 13 which communicates with the cooking cavity 2 through inlet openings (not shown) in the sheet metal forming the top wall of the cooking cavity 2 , said inlet openings being located right above the door 3. the flow b is being heated by crossing the magnetron 9, he won about 40 ° C, then being in a temperature range between 75 and 95 ° C, it has, interestingly, increased its minimum heating and drying from inside of the door 3 and the elements of the cooking cavity 2 in order to prevent condensation therein.

p0026The <figref idrefs="f0001">figures 1</figref> and <figref idrefs="f0004">4</figref> illustrate the airflow in the technical area 4c.

p0027According to the invention, the turbine 11c breath flow directly c Power 10 magnetron 9, which is one of the elements in the technical area 4c to cool, in compliance with the standards, while ensuring good ability to function. Other components may be present in this technical area 4c, but they are not directly concerned with this invention and have therefore not been shown.

p0028According to a preferred feature of the invention, the power supply 10 of the magnetron 9 is in the lower part of the technical area 4c and thus in the lower part of the furnace. This position is particularly advantageous for economic reasons. Indeed, in this position the 10 of the magnetron power supply 9 is directly attached to the bottom of the oven and it is not necessary to provide a reinforced area to greet and this might be necessary if the said power 10 of the magnetron 9 was placed in height.

p0029The technical area is separated 4c technical areas 4d and 4e by a perforated wall 14 whose main role is to maintain the cavity 2 in position. The number and position of openings 15 present in this wall may be varied without departing from the scope of the invention as long as it is provided at least one opening 15 allowing the flow c joining the technical area 4^e, Either directly or through the technical area 4d.

p0030The <figref idrefs="f0001">figures 1</figref> and <figref idrefs="f0005">5</figref> illustrate the airflow in the zone 4d.

p0031In a preferred embodiment of the invention, the stream b apparent from the cooking cavity 2 through outlet openings (not shown) located in the upper part of the cooking cavity 2, said outlet openings may be on the the upper wall of the cooking cavity 2, or in the upper part of the vertical walls of the cooking cavity 2.

p0032Once out of the cooking cavity 2, the stream b is guided to the technical area 4d which is located on one side of the oven, or preferably on both sides thereof.

p0033According to the invention, the stream b then joined below the furnace to the fourth technical area.

p0034The <figref idrefs="f0001">figures 1</figref> and <figref idrefs="f0006">6</figref> illustrate the flow of air into the fourth area.

p0035According to the invention, flows b and c converge in the fourth technical area before exiting the oven through the openings 6 positioned in the lower part of the front of the oven, beneath the door 3.

p0036It is possible, within the scope of the invention, depending on the number and arrangement of the openings 15 and reports flow pressures b and c, the mixture flows b and c begins in the border areas between technical zones 4c and 4d. This does not affect the effectiveness of the ventilation realized. Indeed, once in the 4d technical area, flow b is no longer needed and its temperature may be arbitrary. As for the flow c, it is blown directly on the magnetron 10 supply 9 and creates a movement of air in the immediate vicinity of the feed 10 of the magnetron 9, preventing the arrival of parasites flow whose temperature could be higher that said stream c. The conditions of functioning are not affected by the lack of control can the mixing zone flows b and c.

p0037It is equally possible, without departing from the scope of the invention, the flows b and c are fully channeled to the outlet openings 6 dedicated to each stream, and therefore they do not mix inside of the chamber 1 of the furnace.

p0038According to one embodiment of the invention, the magnetron 10 supply 9 is a high voltage transformer. It is equally possible that this is a switching power supply or "inverter".

p0039Similarly, it is also possible in another embodiment of the invention that air inlet 5 is always in the upper part of the oven front, but above the strip 8 for controlling or it is separated into several openings around the control panel 8.

p0040An interesting result is that a furnace according to the invention preserves this furniture around said oven. Indeed, the humid exhaust air at the air outlet 6 will not go directly touch the furniture located above the mounting of the oven niche. He will have time to become diluted and therefore have a lower moisture content prior to contact with cooler surfaces and likely to fear moisture.

p0041Another interesting consequence of the invention is that the fan 11 located relatively far from the air outlet 6, the velocity of air exiting the furnace is not very high and thus limits the risk of discomfort for the user standing in front of the oven. The user feels a stream of air less strong than if the fan was in the immediate vicinity of the outlet. Moreover, again thanks to the relatively large distance that flows inside the enclosure 1, the air is output at a substantially lower temperature than that found in general the output of this type 'apparatus. The air expelled from the kiln according to the invention has a temperature within a range between 35 and 55 ° C and ideally close to 45 ° C.

p0042The features described above are those of a microwave oven using the single cooking means, but the invention can also be applied to a furnace having, in addition to the cooking mode by microwaves, other modes of cooking can operate alone or in combination, such as a grill mode (direct heating through armored resistance, quartz or halogen) or convection method (injection into the cavity through a fan, heated air with a sheathed resistance).

p0043The invention meets the need to achieve an internal ventilation of a recessed microwave oven, a simple, efficient and cost and allowing installation in any niche kitchen with standard dimensions without imposing in said niche specific areas to ensure air circulation and this in the best respect the surrounding furniture and comfort of the user.