[0001] The invention relates to a microwave cooking appliance, including:
an interior chamber, including a cooking space for accommodating foodstuffs to be
cooked;
an apparatus for providing microwaves of at least one wavelength λ to the interior
chamber; and
at least one plate-like member having at least one surface reflective to microwaves
and facing an opposite surface reflective to microwaves in the interior chamber,
wherein the plate-like member is movable such as to vary a distance to the opposite
surface whilst the microwaves are provided to the interior chamber.
[0002] The invention also relates to a method of operating a microwave cooking appliance,
in particular a microwave cooking appliance according to any one of the preceding
claims, the cooking appliance including:
an interior chamber, including a cooking space for accommodating foodstuffs to be
cooked;
an apparatus for providing microwaves of at least one wavelength λ to the interior
chamber; and
at least one plate-like member having at least one surface reflective to microwaves
and facing an opposite surface reflective to microwaves in the interior chamber,
wherein the plate-like member is allowed to move such as to vary a distance to the
opposite surface whilst the microwaves are provided to the interior chamber.
[0003] An example of such an appliance and method is known.
GB 1 105 021 B discloses a heating apparatus or oven construction including an electrically conducting
oven liner or member having a polished inner surface defining a resonant cavity. The
cavity contains conventional electric heating elements as well as a pedestal or tuning
assembly for tuning the cavity and a coupling assembly for coupling radio frequency
energy to the cavity from a fixed frequency oscillator. The pedestal is adjustable
in height. The adjustable tuning assembly and coupling assembly return the resonant
cavity to the frequency of the oscillator to ensure a maximum transfer of energy from
the oscillator to the food. This does not ensure the absence of hot and cold spots.
To accomplish this, the height of the cavity is made less than one wavelength of the
frequency supplied by the oscillator to avoid standing waves and the problems introduced
thereby. In an embodiment, the settings of the tuning assembly and the coupling assembly
are continuously varies relative to each other. Because the continuous oscillation
of the tuning assembly and the coupling assembly occur in quasi random relation to
each other, the settings of these two assemblies will soon approach the relationship
necessary to tune the resonant oven cavity to the oscillator. At this time, the tuning
assembly and coupling assembly are arrested in the proper positions relative to each
other in which the resonant cavity is tuned to the oscillator.
[0004] A problem of the known appliance is that it is too small to be suitable for use in
large kitchens. The provision of a stack of resonant cavities would require duplication
of the coupling assemblies and tuning assemblies.
[0005] US 2,648,760 discloses a hollow rectangular or prismoidal enclosure or cavity made of a suitable
metal, adapted to serve as the oven of a heating or cooking apparatus. A magnetron
is energised from any suitable source, and when so energised delivers high-frequency
electromagnetic energy having a predetermined wavelength to a coaxial transmission
line, an inner conductor of which is coupled to an oscillator of the magnetron and
the outer conductor of which is connected to an evacuated envelope of the magnetron.
The inner conductor of the line extends directly into the interior of the oven through
a suitable opening provided in a rear wall thereof. A thin metallic plate member,
which may have substantially square upper and lower faces, is mounted horizontally
inside the cavity near the upper end thereof The dimensions of the faces of this plate
member are somewhat smaller than the corresponding dimensions of the oven, but the
face dimensions are each a substantial proportion of the corresponding oven dimensions,
such as on the order of three-fourths thereof, for example. The plate is fixed to
a shaft, which extends through an upper wall of the oven by means of a hole in the
central area thereof. The shaft is mounted for vertical reciprocation with respect
to the oven in a suitable bearing fixed to the top wall of the oven. The shaft is
adapted to be continuously reciprocated vertically. As the metallic plate is reciprocated,
in effect the internal height of the cavity is continuously and periodically varied
to a predetermined extent, since the metallic plate "looks" like the upper wall of
the enclosure to the high-frequency electromagnetic waves inside the cavity.
[0006] It is an object of the invention to provide a microwave cooking appliance and method
of the types mentioned above in the opening paragraphs that are able to provide even
heating in large cooking spaces.
[0007] This object is achieved by the microwave cooking appliance according claim 1.
[0008] In an embodiment, at least one of the plate-like members substantially delimits the
cooking space to one side thereof.
[0009] In a variant of this embodiment, the interior chamber has a floor, the at least one
plate-like members delimiting the cooking space only to a respective side thereof
that is generally transverse to the floor.
[0010] At least one plate-like member may substantially partition the interior chamber into
the cooking space and at least one further space, in particular a further space accommodating
a fan wheel.
[0011] In a variant of this embodiment, the plate-like member substantially partitioning
the interior chamber is suspended, in particular from one or more surfaces defining
the interior chamber, by at least one device including a resilient element.
[0012] Furthermore, this embodiment of the microwave cooking appliance may further include
a control apparatus for varying a pressure difference between the further space and
the cooking space so as to reposition the plate-like member substantially partitioning
the interior chamber.
[0013] Also, the plate-like member substantially partitioning the interior chamber may be
arranged to leave free an opening at at least one edge between the plate-like member
and a surface defining the interior chamber.
[0014] The microwave cooking appliance may also include an apparatus for causing continual
reciprocating movement of the plate-like member whilst the microwaves are provided
to the interior chamber, in particular at a frequency in a range of 5-50 min
-1.
[0015] According to another aspect, a method of operating a microwave cooking appliance
according to claim 9 is provided.
[0016] The invention is based on the surprising insight that, because at least one of the
plate-like members is movable such as to allow a change in the distance to the opposite
surface by an amount of the order of at least a quarter wavelength λ, it is possible
for the positions of maxima and minima of a standing wave field distribution established
in the interior chamber including the cooking space to be substantially interchanged.
As a result, the cooking space can be large enough to form a resonant cavity without
adverse consequences for the energy distribution in the cooking space. Because the
distance between opposite reflective surfaces is allowed to vary whilst the microwaves
are provided to the interior chamber, the surfaces that would otherwise cause standing
wave patterns are moved.
[0017] Where at least one of the plate-like members substantially delimits the cooking space
to one side thereof, the cooking space is not obstructed by the plate-like member
or members. Moreover, the homogeneity of the energy distribution is improved across
substantially the entire cooking space. The distance between reflecting surfaces on
either side of the cooking space is varied at substantially all levels.
[0018] If the interior chamber has a floor and the at least one plate-like members delimits
the cooking space only to a respective side thereof that is generally transverse to
the floor, then the ceiling and floor do not comprise or support plate-like members.
This embodiment is structurally easier to achieve, because the floor already supports
the foodstuffs, or at least accessories for carrying the foodstuffs, and may additionally
comprise components of an arrangement for draining the cooking space of moisture,
e.g. cleaning liquids. The ceiling area can similarly comprise devices, e.g. a device
for showering cleaning liquid into the cooking space, when empty, or a device for
spraying aromas or other substances onto the foodstuffs in the cooking space. Moreover,
it is generally desirable to keep the overall height of the cooking appliance low
without decreasing the interior height of the cooking space, for which purpose one
may wish to avoid horizontal plate-like members, at least in the cooking space.
[0019] If the at least one plate-like member substantially partitions the interior chamber
into the cooking space and at least one further space, in particular a further space
accommodating a fan wheel, then an additional plate-like member need not be provided.
A partitioning member of this type is common in microwave cooking appliances with
means for circulating the cooking atmosphere. This embodiment also makes more efficient
use of available space, because the plate-like member must generally be additional
to the walls defining the interior chamber. Those walls must be arranged to prevent
microwave leakage. They cannot easily comprise the plate-like member for that reason.
[0020] If the plate-like member substantially partitioning the interior chamber is carried
by, in particular suspended from, one or more surfaces defining the interior chamber,
by at least one device including a resilient element, then at least some of the movement
of the plate-like member can be brought about without energising an actuator. Suspending
the plate-like member by means of resilient elements obviates the need for bearings,
making the construction cheaper. In particular if the appliance further includes a
control apparatus for varying a pressure difference between the further space and
the cooking space so as to reposition the plate-like member substantially partitioning
the interior chamber, no separate actuators need be provided to move the plate-like
member. Reciprocating movement can be brought about by increasing and decreasing the
pressure difference between the further space and the cooking space against the force
exerted by the resilient elements on the plate-like member.
[0021] A recirculation of the atmosphere in the cooking space is brought about using a plate-like
member substantially partitioning the interior chamber that is arranged to leave free
an opening at at least one edge between the plate-like member and a surface defining
the interior chamber. One or more openings in the plane of the plate-like member are
provided for drawing the atmosphere from the cooking space into the further space.
[0022] An apparatus for causing continual reciprocating movement of the plate-like member
whilst the microwaves are provided to the cooking chamber, in particular at a frequency
in a range of 5-50 min
-1, ensures that no portion of the foodstuffs in the cooking space is left at a minimum
in the field distribution for a prolonged fraction of the typical duration of a microwaving
cooking operation.
[0023] With the method of operating the microwave cooking appliance an electromagnetic field
distribution having minima and maxima can be established in at least the cooking space,
but locations of the minima and maxima are continually changed by the movement of
the at least one plate-like member during the microwave cooking process.
[0024] The invention will be explained in further detail with reference to the accompanying
drawings, in which like parts are referred to by the same reference numerals, and
in which:
- Fig. 1
- is a schematic cross-sectional top view a cooking appliance with movable metal plates;
- Fig. 2
- is a schematic cross-sectional view from the front of a first variant of the cooking
appliance with a movable partition; and
- Fig. 3
- is a schematic cross-sectional view from the front of a second variant of the cooking
appliance with a movable partition suspended by means of resilient elements.
[0025] Fig. 1 shows a cooking appliance 1 comprising an interior chamber substantially partitioned
into a cooking space 2 and a pressure space 3 by means of a fluid guide member 4.
The interior chamber is defined by a back wall 5, left and right side walls 6,7 and
a door 8, as well as by a ceiling 9 and floor 10 (Figs. 2 and 3). The walls 5,6,7,
ceiling 9, floor 10 and door 8 are reflective to microwaves, being either made of
metal or provided with a metal coating. In the case of the door 8, a metal mesh (not
shown) can be provided on the inside of an otherwise transparent window, for example.
[0026] Foodstuffs to be heated are accommodated in the cooking space 2, which, in the illustrated
embodiment, comprises a rack 11 for supporting trays 12 or other carriers for foodstuffs
at various levels in the cooking space 2. The rack 11 is just an example of an accessory
for supporting foodstuff carriers. In other embodiments, plate racks or the like can
be provided, or the cooking space can be arranged to accommodate a trolley or a rotisserie
assembly, for example.
[0027] The cooking appliance 1 illustrated in the drawings comprises a fan wheel 13 driven
by a motor 14. The motor 14 is located in an electrical equipment chamber 15 and connected
to the fan wheel 13 by means of an axle 16 extending through the side wall 6 in such
a manner as substantially to prevent microwave leakage. The fan wheel 13 is part of
a centrifugal fan, sucking in the cooking space atmosphere through a central opening
17 in the plane of the fluid guide member 4 and expelling it radially. The gases,
fumes and vapour return to the cooking space by way of slits 18,19 left free at edges
of the fluid guide member 4, by virtue of the fact that the centrifugal fan establishes
a pressure difference between the pressure space 3 and the cooking space 2.
[0028] Although not shown, conventional electrical resistance heater elements can be placed
in the flow generated by the central fan to provide electrical heating of the cooking
space 2. Additionally, injectors of vapour, aromas and the like can be present in
the cooking appliance 1.
[0029] In the illustrated embodiments, the cooking appliance 1 further includes a microwave
generator 20, e.g. a magnetron, and a waveguide 21 for providing microwaves generated
by the microwave generator to the interior chamber. The microwave generator 20 generates
electromagnetic waves with a frequency of about 2.45 GHz, which translates to a wave-length
λ of about 12 cm. In other embodiments, other frequencies are used. In the illustrated
embodiment, the waveguide 21 is provided with an aperture or antenna (not shown) for
emitting microwave radiation into the pressure space 3 adjacent the cooking space.
Both the pressure space 3 and cooking space 2 are dimensioned such that they can form
resonant cavities, being typically several wavelengths deep and high and, in the case
of the cooking space, wide.
[0030] Normally, an electromagnetic field distribution would form in an oven cavity of the
dimensions indicated above, the field distribution having fixed minima and maxima.
This could lead to an uneven cooking result. The position of the minima and maxima
depends on several factors, including the resonant frequency, the dimensions and geometry
of the oven cavity, the dimensions and configuration of antennas or waveguide apertures
for feeding the microwaves into the oven cavity, the presence and configuration of
foodstuffs and accessories in the oven cavity, etc.
[0031] The illustrated cooking appliance 1 is provided with first and second plate-like
members 22,23 that are movable so as to vary the distance between them and opposite
reflective surfaces delimiting the cooking space 2, in this case, the inside surface
of the door 8 and the fluid guide member 4, respectively. In addition, the fluid guide
member 4 is movable in a direction transverse to its plane, just like the first and
second plate-like members 22,23.
[0032] The first and second plate-like members 22,23 and the fluid guide member 4 are movable
whilst microwave energy is being fed into the interior chamber. Because they delimit
the cooking space 2 to the rear and to the sides, the dimensions of the resonant cavity
comprising the cooking space 2 change, in use, and thus also the positions of the
minima and maxima of the electromagnetic field distribution. Over a period typical
for most cooking operations (several minutes), the positions may be changed from five
to fifty times, for example, so that the average energy distribution over the cooking
period is relatively homogeneous.
[0033] In the illustrated embodiment, the plate-like members 22,23 extend in height over
the major part of the height of the cooking space 2 (distance between floor 10 and
ceiling 9), e.g. more than 80 % or even 90 %, so that a relatively large degree of
homogeneity of the microwave energy distribution at substantially all levels can be
achieved. This is an effect that would be hard to achieve with only one or a few mode
stirrers that are conventionally used to achieve a more homogeneous energy distribution.
It also allows one to provide only one waveguide 21 or antenna, or at least a limited
number thereof. Similarly, the first plate-like member 22 substantially delimits the
cooking space 2 in the sense that it extends over the major part of the width thereof
(distance between fluid guide member 4 and opposite side wall 7), e.g. more than 80
or 90 % of the width. In an alternative embodiment (not shown), the first plate-like
member 22 substantially covers the entire rear wall 5 of the interior chamber.
[0034] In the illustrated embodiment, actuators 24,25,26,27 are provided for moving the
first and second plate-like members 22,23. Any suitable type of actuator can be used,
including mechanical or electromagnetic actuators, for example. The amplitude of movement
of the first and second plate-like members 22,23 is at least equal to a quarter of
the wave-length of the microwaves, i.e. about 3 cm or more. This ensures substantial
displacement of the maxima and minima of the electromagnetic field distribution. Movement
may be continuous, e.g. sinusoidal, or the position of the plate-like members 22,23
can be changed at intervals in a step-like manner.
[0035] The characteristics of the movement of the plate-like members 22,23 correspond to
those for the fluid guide member 4. However, the actuator mechanisms can differ, two
alternatives being illustrated in Figs. 2 and 3 respectively.
[0036] In the first alternative (Fig. 2), the fluid guide member 4 is suspended between
the ceiling 9 and floor 10 of the interior chamber by means of pins 28,29 that travel
in apertures (not shown in detail) in the ceiling 9 and floor 10. Actuators (not shown)
provided outside the interior chamber move the pins 28,29 such that the fluid guide
member 4 reciprocates in a directions generally transverse to its plane. The actuators
can include an electrical motor or an electromagnetic actuator, for example.
[0037] In the embodiment of Fig. 3, the fluid guide member 4 is suspended from the floor
10 and ceiling 9 of the interior chamber by means of resilient elements 30,31 in the
form of coil springs. Other types of element may be used. The resilient elements 30,31
can be made of plastics or spring steel, for example. They are sufficiently flexible
to allow the fluid guide member 4 to move over a distance in the order of several
centimetres towards and away from the upright side wall 6 of the interior chamber.
They provide a restoring force tending in the same direction. This force counters
the force due to the pressure difference between the pressure space 3 and the cooking
space 2 (i.e. the pressure difference between the two sides of the fluid guide member
4). In use, the position of the fluid guide member 4 is changed periodically by adjusting
the pressure difference between the pressure space 3 and the cooking space 2. To this
end, an appropriate control device adjusts the settings of the centrifugal fan.
[0038] The embodiment of Fig. 3 thus requires no additional actuators. Moreover, the suspension
arrangement does not extend through either the ceiling 9 or the floor 10 of the interior
chamber. This makes it easier to seal off the interior chamber to prevent microwaves
and/or fumes escaping.
[0039] The continual adjustment of the electromagnetic field distribution in the interior
chamber, in particular in the cooking space 2 ensures that the foodstuffs at the different
levels and at different positions on the trays 12 are heated at approximately the
same rate.
[0040] The invention is not limited to the embodiments described above, which may be varied
within the scope of the accompanying claims. The elements of the invention can be
essential to the invention both individually and in any combination:
[0041] Embodiments in which only the fluid guide member 4 is movable, and in which the other
plate-like members 22,23 are absent, also provide the effects set out above, and are
easy to build, as well as being easy to clean, in use.
LIST OF REFERENCE NUMERALS
[0042]
- 1
- Cooking appliance
- 2
- Cooking space
- 3
- Pressure space
- 4
- Fluid guide member
- 5
- Back wall
- 6
- Left side wall
- 7
- Right side wall
- 8
- Door
- 9
- Ceiling
- 10
- Floor
- 11
- Rack
- 12
- Tray
- 13
- Fan wheel
- 14
- Motor
- 15
- Equipment chamber
- 16
- Axle
- 17
- Opening
- 18
- Slit
- 19
- Slit
- 20
- Microwave generator
- 21
- Waveguide
- 22
- First plate-like member
- 23
- Second plate-like member
- 24
- Actuator
- 25
- Actuator
- 26
- Actuator
- 27
- Actuator
- 28
- Pin
- 29
- Pin
- 30
- Resilient element
- 31
- Resilient element
1. Microwave cooking appliance, including:
an interior chamber, including a cooking space (2) for accommodating foodstuffs to
be cooked;
an apparatus (20,21) for providing microwaves of at least one wavelength λ to the
interior chamber, and
at least one plate-like member (4,22,23) having at least one surface reflective to
microwaves and facing an opposite surface reflective to microwaves in the interior
chamber,
wherein the plate-like member (4,22,23) is movable such as to vary a distance to the
opposite surface whilst the microwaves are provided to the interior chamber,
characterised in that
at least one of the plate-like members (4,22,23) is movable such as to allow a change
in distance to the opposite surface by an amount equal to at least a quarter of the
at least one wavelength λ.
2. Microwave cooking appliance according to claim 1, wherein
at least one of the plate-like members (4,22,23) substantially delimits the cooking
space (2) to one side thereof.
3. Microwave cooking appliance according to claim 2, wherein the interior chamber has
a floor (10), the at least one plate-like members (4,22,23) delimiting the cooking
space (2) only to a respective side thereof that is generally transverse to the floor
(10).
4. Microwave cooking appliance according to any one of the preceding claims,
wherein
at least one plate-like member (4) substantially partitions the interior chamber into
the cooking space (2) and at least one further space (3), in particular a further
space (3) accommodating a fan wheel (13).
5. Microwave cooking appliance according to claim 4, wherein
the plate-like member (34) substantially partitioning the interior chamber is sus
pended, in particular from one or more surfaces (10,9) defming the interior chamber,
by at least one device including a resilient element (30,31).
6. Microwave cooking appliance according to claims 4 and 5, further including a control
apparatus for varying a pressure difference between the further space (3) and the
cooking space (2) so as to reposition the plate-like member (4) substantially partitioning
the interior chamber.
7. Microwave cooking appliance according to any one of claims 4-6, wherein the plate-like
member (4) substantially partitioning the interior chamber is arranged to leave free
an opening (18,19) at at least one edge between the plate-like mem ber (4) and a surface
(10,9) defming the interior chamber.
8. Microwave cooking appliance according to any one of the preceding claims, including
an apparatus (24,25,26,27,28,29) for causing continual reciprocating movement of the
plate-like member (4,22,23) whilst the microwaves are provided to the interior chamber,
in particular at a frequency in a range of 5-50 min-1.
9. Method of operating a microwave cooking appliance (1) according to any one of the
preceding claims, the cooking appliance including:
an interior chamber, including a cooking space (2) for accommodating foodstuffs to
be cooked;
an apparatus (20,21) for providing microwaves of at least one wavelength λ to the
interior chamber: and
at least one plate-like member (4,22,23) having at least one surface reflective to
microwaves and facing an opposite surface reflective to microwaves in the interior
chamber,
wherein the plate-like member (4,22,23) is allowed to move such as to vary a distance
to the opposite surface whilst the microwaves are provided to the interior chamber,
wherein
an electromagnetic field distribution having minima and maxima is established in at
least the cooking space (2), and locations of the minima and maxima are changed by
the movement of the at least one plate-like member (4,22,23).
1. Mikrowellen-Gargerät, umfassend:
eine innere Kammer, die einen Garraum (2) zur Aufnahme von zu garenden Lebensmitteln
umfasst,
ein Gerät (20, 21) zur Bereitstellung von Mikrowellen mit mindestens einer Wellenlänge
λ in die innere Kammer, und
mindestens ein plattenartiges Element (4, 22, 23), das mindestens eine Oberfläche
aufweist, die Mikrowellen reflektiert und zu einer gegenüberliegenden, Mikrowellen
reflektierenden Oberfläche in der inneren Kammer weist,
wobei das plattenartige Element (4, 22, 23) so bewegbar ist, dass während der Bereitstellung
der Mikrowellen in die innere Kammer ein Abstand zu der gegenüberliegenden Oberfläche
variiert wird,
dadurch gekennzeichnet, dass
mindestens eines der plattenartigen Elemente (4, 22, 23) so bewegbar ist, dass eine
Änderung des Abstands zu der gegenüberliegenden Oberfläche in einem Ausmaß möglich
ist, das mindestens einem Viertel der mindestens einen Wellenlänge λ entspricht.
2. Mikrowellen-Gargerät nach Anspruch 1, wobei mindestens eines der plattenartigen Elemente
(4, 22, 23) den Garraum (2) im Wesentlichen auf einer Seite desselben begrenzt.
3. Mikrowellen-Gargerät nach Anspruch 2, wobei die innere Kammer einen Boden (10) aufweist,
wobei das mindestens eine plattenartige Element (4, 22, 23) den Garraum (2) nur auf
einer jeweiligen Seite desselben begrenzt, die im Wesentlichen quer zu dem Boden (10)
verläuft.
4. Mikrowellen-Gargerät nach einem der vorangehenden Ansprüche, wobei mindestens ein
plattenartiges Element (4) die innere Kammer im Wesentlichen in den Garraum (2) und
mindestens einen weiteren Raum (3), insbesondere einen weiteren Raum (3), der ein
Lüfterrad (13) aufnimmt, unterteilt.
5. Mikrowellen-Gargerät nach Anspruch 4, wobei das die innere Kammer im Wesentlichen
unterteilende plattenartige Element (34) mittels mindestens einer ein elastisches
Element (30, 31) umfassenden Vorrichtung, insbesondere an einer oder mehreren Oberfläche(n)
(10, 9), welche die innere Kammer definieren, aufgehängt ist.
6. Mikrowellen-Gargerät nach den Ansprüchen 4 und 5, ferner umfassend: ein Steuergerät
zum Variieren eines Druckunterschieds zwischen dem weiteren Raum (3) und dem Garraum
(2), um das plattenartige Element (4), das die innere Kammer im Wesentlichen unterteilt,
anders zu positionieren.
7. Mikrowellen-Gargerät nach einem der Ansprüche 4-6, wobei das die innere Kammer im
Wesentlichen unterteilende plattenartige Element (4) so angeordnet ist, dass an mindestens
einem Rand zwischen dem plattenartigen Element (4) und einer die innere Kammer definierenden
Oberfläche (10, 9) eine Öffnung (18, 19) frei bleibt.
8. Mikrowellen-Gargerät nach einem der vorangehenden Ansprüche, umfassend: ein Gerät
(24, 25, 26, 27, 28, 29) zum Bewirken einer dauernden Hin- und Herbewegung des plattenartigen
Elements (4, 22, 23) während der Bereitstellung der Mikrowellen in die innere Kammer,
insbesondere mit einer Frequenz im Bereich von 5-50 min-1.
9. Verfahren zum Betrieb eines Mikrowellen-Gargeräts (1) nach einem der vorangehenden
Ansprüche, wobei das Gargerät umfasst:
eine innere Kammer, die einen Garraum (2) zur Aufnahme von zu garenden Lebensmitteln
umfasst,
ein Gerät (20, 21) zur Bereitstellung von Mikrowellen mit mindestens einer Wellenlänge
λ in die innere Kammer, und
mindestens ein plattenartiges Element (4, 22, 23), das mindestens eine Oberfläche
aufweist, die Mikrowellen reflektiert und zu einer gegenüberliegenden, Mikrowellen
reflektierenden Oberfläche in der inneren Kammer weist,
wobei das plattenartige Element (4, 22, 23) so beweglich ist, dass während der Bereitstellung
der Mikrowellen in die innere Kammer ein Abstand zu der gegenüberliegenden Oberfläche
variiert wird, wobei
mindestens im Garraum (2) eine Minima und Maxima aufweisende elektromagnetische Feldverteilung
erzeugt wird, und Orte der Minima und Maxima durch die Bewegung des mindestens einen
plattenartigen Elements (4, 22, 23) geändert werden.
1. Appareil de cuisson à micro-ondes, comprenant :
une chambre intérieure, comprenant un espace de cuisson (2) destiné à recevoir des
aliments à cuire ;
un appareil (20, 21) permettant d'acheminer des micro-ondes d'au moins une longueur
d'onde λ dans la chambre intérieure, et
au moins un élément en forme de plaque (4, 22, 23) ayant au moins une surface réfléchissant
les micro-ondes, et dirigé vers une surface opposée réfléchissant les micro-ondes
dans la chambre intérieure,
dans lequel l'élément en forme de plaque (4, 22, 23) est mobile de manière à faire
varier la distance jusqu'à la surface opposée pendant que les micro-ondes sont acheminées
dans la chambre intérieure,
caractérisé en ce que
au moins un des éléments en forme de plaque (4, 22, 23) est mobile, de manière à permettre
un changement de la distance jusqu'à la surface opposée d'une quantité égale à au
moins un quart de la au moins une longueur d'onde λ.
2. Appareil de cuisson à micro-ondes selon la revendication 1, dans lequel au moins un
des éléments en forme de plaque (4, 22, 23) délimite sensiblement l'espace de cuisson
(2) à un de ses côtés.
3. Appareil de cuisson à micro-ondes selon la revendication 2, dans lequel la chambre
intérieure a un plancher (10), les éléments en forme de plaque (4, 22, 23) délimitant
l'espace de cuisson (2) uniquement à un de ses côtés respectifs qui est généralement
transversal au plancher (10).
4. Appareil de cuisson à micro-ondes selon l'une quelconque des revendications précédentes,
dans lequel
au moins un élément en forme de plaque (4) divise sensiblement la chambre intérieure
en l'espace de cuisson (2) et au moins un espace supplémentaire (3), en particulier
un espace supplémentaire (3) recevant une roue de ventilateur (13).
5. Appareil de cuisson à micro-ondes selon la revendication 4, dans lequel l'élément
en forme de plaque (34) divisant sensiblement la chambre intérieure est suspendue,
en particulier à partir d'une ou plusieurs surfaces (10, 9) définissant la chambre
intérieure, par l'intermédiaire d'au moins un dispositif comprenant un élément élastique
(30, 31).
6. Appareil de cuisson à micro-ondes selon les revendications 4 et 5, comprenant en outre
un appareil de commande permettant de faire varier une différence de pression entre
l'espace supplémentaire (3) et l'espace de cuisson (2) de manière à repositionner
l'élément en forme de plaque (4) divisant sensiblement la chambre intérieure.
7. Appareil de cuisson à micro-ondes selon l'une quelconque des revendications 4 à 6,
dans lequel l'élément en forme de plaque (4) divisant sensiblement la chambre intérieure
est agencé pour laisser une ouverture (18, 19) de libre au niveau d'au moins un côté
entre l'élément en forme de plaque (4) et une surface (10, 9) définissant la chambre
intérieure.
8. Appareil de cuisson à micro-ondes selon l'une quelconque des revendications précédentes,
comprenant :
un appareil (24, 25, 26, 27, 28, 29) permettant d'entraîner un déplacement en va-et-vient
continu de l'élément en forme de plaque (4, 22, 23) pendant que les micro-ondes sont
acheminées dans la chambre intérieure, en particulier à une fréquence se trouvant
dans une plage comprise entre 5 et 50 min-1.
9. Procédé de fonctionnement d'un appareil de cuisson à micro-ondes (1) selon l'une quelconque
des revendications précédentes, l'appareil de cuisson comprenant :
une chambre intérieure, comprenant un espace de cuisson (2) permettant de recevoir
des aliments à cuire ;
un appareil (20, 21) pour acheminer des micro-ondes d'au moins une longueur d'onde
λ dans la chambre intérieure ; et
au moins un élément en forme de plaque (4, 22, 23) ayant au moins une surface réfléchissant
les micro-ondes, et dirigé vers une surface opposée réfléchissant les micro-ondes
dans la chambre intérieure,
dans lequel l'élément en forme de plaque (4, 22, 23) peut se déplacer de manière à
faire varier la distance jusqu'à la surface opposée pendant que les micro-ondes sont
acheminées dans la chambre intérieure, dans lequel
une répartition de champ électromagnétique ayant des minimums et des maximums est
établie dans au moins l'espace de cuisson (2), et les emplacements des minimums et
des maximums sont modifiés par le déplacement d'au moins un élément en forme de plaque
(4, 22, 23).