DE3120900A1 - Microwave operating space - Google Patents

Abstract

Until now, efforts have been directed at achieving a uniform energy distribution in the microwave operating space, averaged with respect to time, in order to achieve homogeneous heating of an object. This is adequate for relatively small objects but not, for example, for deep-frozen chickens or gateaux. In this case, an energy concentration at the centre of the object is essential so that, together with the necessary adsorption, there is a uniform (or even increased at the centre) energy level per cm<3>. This is achieved, however, only according to the invention, by means of interference of coherent or incoherent radiation from at least two radiation sources, the coherent radiations producing higher maxima and minima and providing greater capabilities for the distribution of the energy. This all takes place exclusively in the primary beam, that is to say the interference must be completed before the radiation can be reflected on the wall parts and hence lead to undefined phases and polarisation directions. If necessary, as normal, rotary or linear movements of the object are carried out. Typical examples are shown of these advances.

Description

German Patent Office Munich 23-5.81

Application for patent alternatively QBM Microwave workroom addition to 29 IO 961 *

In today's microwave work rooms, the HF fields are influenced by special means so that at the point of the object in the time averaging a homogeneous energy distribution is achieved.

This is sufficient for relatively small and not strongly absorbing objects, but fails if the thickness of the objects is in the size of Ά and more comes with the usual absorption values. Because because of the inevitable weakening of the originally homogeneous radiation when passing through the edge parts, less energy remains for the putty, the temperature of the interior of the object remains lower than that of the belt parts. . ' Well-known examples:

A frozen chicken can be charred on the outside when heated up quickly, while there is still tleff rest in the middle.

A frozen cream cake runs in today's stoves outside liquid together over an inner ice core.

At normal starting temperatures the conditions are similar, only less noticeable.

Today's method of stretching the times or feeling them in impulses, Is not a solution to the problem. .

Rather, it requires the energy to be applied to the center of the object concentrate to a certain extent. ^ Based on the main registration and further training of the performances there, this is possible as follows:

Concentration electrically means the superposition of at least 2 Wave trains at the desired location. Lens and concave mirror fail for reasons of dimensioning. It has been shown that satisfactory effects can be achieved with 2 or more separate radiation sources.

The sketch shows a work room with 2 radiation jellyfish, here facing each other. The sources are windows or equivalent antenna constructions at the ends of power supply lines

-— "temperature distribution l.cyl.obj · up to now: wrong new: right

2>. 1 - «<f ρ -« - «- ^ r-- r

source

The two wave trains come from different sensor tubes without a frequency relationship to one another, the frequencies belong to the same frequency range, but are not identical. So that the Sencer tubes do not interfere with each other, directional elements are attached to the supply lines with the same polarization or the polarizations are perpendicular to one another. Before wall reflections take effect, the energy of the primary radiation declines with one or more higher powers (ways of the llah- feider); see curves 1 of the sketch.

The sum of both irradiations in the middle reaches almost double the V. er "c vie in the neighboring minimum through scalar addition; see curve 2.

This 2: 1 concentration is ready for many application examples! sufficient. If an object is brought into the putty, the edge of which: fall roughly into the minima, the ΚΑΣ / ΚΙΪΤ ratio is reduced ideally from 2: 1 to 1: 1, i.e. the object will ' in the middle just as electrically "loaded as at the edge, it." is thus heated homogeneously.

2nd case:

The two wave trains come from the same transmitter tube or controlled by tubes at the same frequency. The sources should be in ! frequency, phase, amplitude and polarization must be the same. Then * - it is known that standing waves occur in the space with a ratio of 1: °° between max. and kin ^ lm distance of ^ / 2 of the Minima curve j3 of the sketch. The drop after curve-2 adds up, Curve 3 naturally dominates the course in the putty. Pike the result for a cylindrical object. When damped by an object, the liax. lowered, because of the energy output, but the min. increased more because of the additional energy supply for the Kax. The application possibilities are more extensive-Im the following is the practical implementation of the ideas mentioned.

.As feed lines have been electrically and mechanically more unexpected Flat waveguides and ribbon cables, i.e. with low wave resistance, have proven their worth. You leave it very well adapt, take up little space and can easily be made part of the walls.

BAD ORSOfNAL

b. '. nit 1 represents the working space, 2 is the supply line; voc Näer (3), 4- aas! window ζ us distribution manager 5 πι it the two sources of information 6. The supervision of sources from above and from below; igt 8 and B ^ depending on the object size of normal width or dcnp- j lter width. In the last lall the window gets in the putty B. a metallic bridge of suitable inductance to widen the noise and to create disturbing vial shapes connect. The area of action is broadened by Anv: en- <

mg of a turntable 7- The object is possibly replaced by suitable Bring the cover to the appropriate room height, as shown in Fig. 2 arch the dashed object indicated.

To replace the turntable or other mechanical displacements arch electrical arrangements, Fig.2 shows a sjti- j etric repetition of the distribution waveguide, fed by the same transmitter ear 9 · The coupling windows 4 and 4 'must be in phase, so a distance of odd' * ^v '^ / 2, so that the sources 6 remain in phase. For a more rectangular object, the windows of the sources are designed like 1C, for a round, e.g. cake, like 10 ', a 2 * transmitter / tube can be used for power control by dividing the waveguide 2 and symmetrically - Coupling of both lines * ... ".... -.

irnisin "mutual cross-coupling from" neighboring windows 6 Avoid 5U, a reflection barrier 11 from e ^ rpericentell to be determined in the form of a metal plate or | Equiv. used. · I

While the figures -1 and 2 are predominantly on one pull, Fig. 3 applies to continuous ovens, especially 'to dry: thin layers. ι

The radiation direction is perpendicular to the insier! _T window level. The radiation sources 6 are therefore set obliquely forwards when the direction of the arrow indicates the object evaluation, the height distance of the room 1 is approximately 3 / ^ - λ. Then, after the primary beam has passed through the object and reflected, the centering process repeats itself in the cement, where the 1 polarization oscillates around the plane of the object. As the right-hand sketch shows, because of the flat object, neighboring windows 6 are in phase. The choice depends on the object.

l ^! The idea represents: an extraordinarily high level of stranding of the performance on the flat project, which meets all modern requirements, for example when drying foils and perbes.

Fig.A-, view from the front, and iVbt.5, view from above, show a continuous furnace in the shape of a cylinder, preferably for liquids or bulk goods, the gtff. is guided in an additional insulating tube. The arrangement Ιεζ- is composed in a manner. 1 is the working space, the direction of the axis is its axis, 5 oil distribution waveguides, 6 the jtrahlunrsfenster, 12 the k ont acre plates for the transmitter tubes, 13 the Einkor ^ eiioch. In the present example case, the reometric addition is also used, ar. This means that the concentration on the center of the object is sharper according to earlier explanations and that the decoupling between two windows 6 following one another in the axial direction is almost total, in the arrangement shown, measured energetically, is less than 1/1000. The diameter From 1 _{greater than ^ 3} , Y> waveforms of the type E _no . can arise, which overcouple a little more. Then, by rotating the axis, two successive building blocks are attached at an angle to each other, so that one is at the radiation minimum of the other Several conductors 5 can again be fed via a common X conductor. In the example, the waveguide 5 is curved over the short side, in principle the curvature over the long '...- .... is equivalent, it allows tube orientation parallel to the axis if required.

r: ee: en the exceptionally good decoupling of the building blocks With this, ovens of any capacity can be assembled in a small space will.

In all cases described, one can control the amplitude and in particular the phase, the latter e.g. by moving of places 4 ·, the position of the i-.ariine in the geometrical height change.

8AD OFTfGfIMAL

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Claims (1)

Claims: * Microwave work room with at least 2 sources of radiation in cLen walls, characterized., > iJ that these sources are so arranged "and operated as" themselves the radiations before any deflection on the Vander · an cer Superimpose ob ^ ektstelle and there in comparison to the immediate Generate an increased energy density in the vicinity of the object. . 2 "as i, characterized in that in the case of Nichtkohcrenz (An ^ ABI) of the radiation sources to avoid nerenseitis-er radiation Aufnahmer | lie Polarisationsrichtunren us QC ^c ^ e-ER are rotated one another or are incorporated in the leads Riehtleiterelemente. 3. As Ι., Characterized in that in the case of coherence (Tv _n = λπ) the 3trahlunp "swell apart from the same frequency also receive the same polarization, phase and amplitude. * i. V7ie upstairs, dad. marked ζ. that the radiation sources the adapted Ends of extremely flat waveguides, e.g. Eohl or strip conductors, possibly with a dielectric insert. 5 »» like 4 ·., Dad. marked. That the radiation sources inside or lie tightly on the outside of the room wall, so that they may contain parts these walls represent. ■ 6. like above, dad. marked that the transmitter tubes are connected via interposed Ladder with higher vertical resistance on the flat ladder be coupled. 7 »*? I® above, flad, marked that the shape and arrangement of the radiation sources aligned with the intended allocation of space is, with extremely wide lenstern 'by r.usrtze v; ie in particular metallic crossbars with a certain induction resistance the desired radiation distribution is enforced. Like 7.ί dad. marked. That to generate rectangular or Sotation symmetry of the radiation distribution in the object of this in the well-known manner shifted or rotated v: ird. 9 »In amendment to 6, dad.gekennz., That through the arrangement of a plurality of lens ■ tern in rectangular or lireissymmetrie and matching the feed Reir gevmnschte Gymmetrie elec- : fresh without moving the object; is achieved. i like 7-9 »dad. marked »that when using not everywhere coherent radiation, the coupling between bensch- bart en! "window through metallic partitions, more defined Saw and possibly special · contours is prevented. 11. as above, dad. It is known that the radiation sources described have their connecting lines. built as independent mechanical construction parts? are sodaB they can absorb the energy through Älemmkontakte · Z.3 "and after - loading must usually in workrooms construction optionally be used by the consumer can-" 12. Continuous ovens with the means indicated above, whereby the P.aumhöae · ca 3 / 4-? V is especially for flat objects (dinghies etc.) and the irradiation is directed obliquely forward and symmetrical. so that the main component of the electrical .field- int essential .izr the. JDbjektefaene falls ». C ure hl on ovens marked with above. Coats, especially for liquids or bulk goods · ».. whereby the work requirement 2.3. tubular with a square odeir-rundent cross-section: extends as long as required and d ± & belonging together; Radiation source]! with their aggregates in building block style .. can be arranged close to each other for any total noise. . copy ¹ bath