FR2533102A1 - HIGH FREQUENCY ENHANCED HEATING APPARATUS - Google Patents

Abstract

THE SUBJECT OF THE INVENTION IS A HIGH FREQUENCY HEATING APPARATUS INCLUDING A HEATING CHAMBER, A HIGH FREQUENCY OSCILLATOR FOR SENDING HIGH FREQUENCY WAVES INTO THE SAID HEATING CHAMBER AND A DOOR TO OPEN AND CLOSE THE OPENING OPENING. THE HEATING CHAMBER. AT THE LOCATIONS OF INTENSE ELECTRIC FIELD IN A THROAT 20 SERVING TO RETAIN A GLASS PLATE 15 COVERING THE OBSERVATION WINDOW, A SERIES OF BOSSES 21 ARE PROVIDED FOR ADJUSTING THE DISPLACEMENT OF THIS GLASS PLATE. COOKING OF FOOD AND OTHER FOODS.

Description

1 - Advanced High Frequency Heater This is

The invention relates to an arrangement of

  door for a high frequency heater.

  Typically, the door of a heating appliance

  high frequency fog, such as a microwave oven,

  carries an observation window to inspect

  the progress of cooking food in the heating chamber during cooking To prevent microwaves from infiltrating through this window, a punched plate consisting of a metal plate having a number of small holes fits the said window On the other hand, to prevent food fragments from plugging the small holes in the punched plate, there is provided a lid consisting of a

glass plate.

  Usually, this glass plate is held in a groove defined by the punched plate, the inner wall of the door and a separate metal member, but

  since the dielectric constant of glass is

  than that of air, as is well known to specialists

  lists, the actual depth of the throat containing the

  that of glass is as follows D '= D C e

  equation in which, D = depth of the throat without ver-

re

  ú = dielectric constant of the glass.

  So this depth becomes much larger

that in the absence of the glass.

  As a result, the real dimension since

  end of the throat to the entrance is close to? / 4, so that the strength of the electric field at

  entrance increases, with a tendency to provoke

  disruptive loads and abnormal rise in temperature

  at the entrance to the gorge Of course, these phenomena

  abnormalities are also strongly influenced by the

  of the electric field in the heating chamber, -2 so that they appear in places where the intense electric field position due to the distribution of the electric field coincides with the aforesaid depth of

the throat.

  To solve this problem, it is necessary that the throat be as shallow as possible, but in

  the construction shown in Figure 1, which is an example

  In conventional practice, the possibility of reducing the depth of the groove is limited so long as the bottom wall 9 of the door and the separate metal member 13 are to be spot welded inside the groove 20 so that the

  head of screw S is not exposed to the internal surface

door 3.

  The subject of the present invention is therefore a high-frequency heating apparatus which eliminates the disadvantage indicated in the prior art and which offers stable quality and reliability for preventing heating.

  abnormal and disruptive discharges into the throat of sup-

wearing of glass.

  To achieve this objective, the invention provides a

  arrangement which comprises a heating chamber, an oscillating

  high-frequency transmitter for sending high-frequency waves into said heating chamber and a door for opening and closing the opening on the front of said

  heating chamber, arrangement in which the

  intense electric field in a throat

  to remember a glass plate covering a window of ob-

  service in said door are provided with a series of

  bosses for adjusting the movement of said cover plate

  The presence of such bosses in the throat decreases the

  depth of the parts of the throat.

  intense force and, as a result, lowers the force of the electric field at the entrance to the throat; so

  this arrangement has the effect of preventing

ruptives and abnormal heating.

  In the accompanying drawings, FIG. 1 is a sectional view of the main part of a high frequency heater which is a classic example;

  Z 2 is a perspective view of an ap-

  same high frequency heating which is an embodiment of the invention; Za Figure 3 is a view from the rear of the door of this apparatus, the inner wall 9 of the door being removed; and FIG. 4 is a section through line A-A 'of

Figure 3.

  We will now describe an embodiment of

  the invention with reference to the drawings.

  In FIG. 2, a main body 1 contains a heating chamber 2 whose opening on the front can

  to be opened or closed by a door 3

  sign a control panel with fluorescent lamps

  displays for displaying timer settings and flow settings, 6-key

  choice of program, a start-up button 7 and a

cancellation tone 8.

  The reference 9 designates the inner wall of the door forming a part of a blocking wall provided on

  the door 3 while 10 is an inspection window through

to the door.

  In FIGS. 3 and 4, reference numeral 11 designates a blocking forge whose depth is equal to approximately 1/4 of the wavelength to be used. The locking groove 11 is defined by the inner wall 9 of the door, the outer wall 12 of the door and a separate metal member 13 connected to the inner wall, for example, by a spot weld. The reference 14 designates a punched plate.

  with a number of small holes for

  kill a quick review window while 15 is a

  glass that prevents food fragments from

  Another small glass plate 16 is provided outside the door 3 whereas the reference 17 designates a handle that is grasped to open and close.

the door 3.

  The entire inner door 9 and the separate metal member 13 is screwed onto the outer wall 12

  of the door to define a groove 20 in which we serve

  re and fix the punched plate 14 and the plate of ver-

  re 15 The reference 18 designates a seal

  which prevents the cracking of the glass and the escape of the

  their and steam released by the current food

Cooking.

  In addition, since the surface of the glass plate 16 carries a coating 19, said screwed portion

  is hidden and invisible from the surface.

  The groove 20 which retains the glass plate 15 pre-

  a series of bosses 21 so that the depth of the portion of the groove provided with said bosses 21 is larger

  low, of a value which corresponds to the height of the

  wise, that the part devoid of bosses 21

  the bosses 21 is about 1/4 of the length

  to use, and the distance between the adjoining bosses

  cents (that is, the step) is about 1/4 of the

  wavelength to be used In the parts having no bosses 21 lparties indicated in the figure by crosses (x) l, it is carried out by spot welding of the organ

  separate metal 13 with the inner wall 9 of the door

  you. The locations where the bosses 21 are provided are determined so as to be close to the most intense electric field as a result of the distribution mode of the electric field in the heating chamber.

  concrete process, these locations can be

  breaking an experimental door without bosses, adjusting it

  both on a test set and by measuring the temperature throughout the groove 20; thus we will know the places where the bosses will have to be placed, that is to say

  the places of the highest temperature.

  - The reason why the bosses should be provided in the manner indicated is that when the glass plate is mounted in the groove 20, which must have at least 9 mm depth to allow spot welding of the inner wall 9 of the gate to the separate metal member 13, the significant depth of the groove relative to the microwaves becomes / times the depth

  in which E is the dielectric constant

  than glass as previously explained Thus, if the dielectric constant of the glass is 5 for example, the

  depth of the throat having a depth of 9 mm

Microwave port is

D = 9 x r E: 20 mm.

  The strength of the electric field at the entrance to the

  age is at its maximum when the depth of the throat is

  approximately 30 mm, which represents 1/4 of the length of

  of use, but since the greater depth due to the glass plate fitted in the groove is close to X / 4, as previously explained, when the maximum point of the distribution of the electric field in the heating chamber is in the vicinity of this value, disruptive discharges-and abnormal rise in temperature take place.

  The present embodiment prevents such a phenomenon

  nomene by providing bosses in the throat 20 to the

  where the electric field is intense to reduce

  thus at the same time, the presence of the bosses 21 decreases the format of the plate of

  glass to be mounted; there is therefore a double effect of diminishing

  the depth of the throat so that the

  Disruptive charges and abnormal heating are avoided.

  When there is an intense electric field location due to the distribution of the electric field in the heating chamber, the next location of intense electric field is distant from the first location by about half the wavelength used. If the width t of a boss 21 is about / 4 and if the distance from the center of one boss 21 to the center of another boss 21 is X / 2, the desired effect can be obtained at all times. points of the maximum electric field for step P. As mentioned above, the invention provides

the following advantages.

  (1) Since bosses are provided in the holding groove of the glass plate at the maximum electric field location because of the distribution pattern of the

  electric field in the heating chamber, one can em-

  fishing for abnormal climatic

  hotspots without any trouble with respect to

  lasts through points of the inner wall of the door to the

separate metal frame.

  (2) Since the presence of the bosses in the groove makes it possible to reduce the depth of the groove in the corresponding parts and at the same time, the format of

  the glass plate, we obtain a double effect of diminishing

  depth of the throat and can therefore be adjusted

  at a sufficiently low value the electric field at

throat.

  (3) Since the bosses in the groove have a width of about 1/4 of the wavelength used, even if the frequency of oscillation of the high frequency oscillator changes more or less depending on the conditions load in the heating chamber can be obtained a

sufficient stabilizing effect.

  (4) If the groove does not have a boss, we must install

  a seal having a cross-section

  dirty enough to fill the entire throat so

  stably hold the glass plate; however, the presence of a series of bosses allows a smaller section trim to adequately retain the plate

of glass, which is economical.

7-

Claims (3)

  1. High frequency heating apparatus includes   a heating chamber, a high frequency oscillator   for sending high frequency waves into said heating chamber (2) and a door (3) for opening and closing the opening in the front of the heating chamber, characterized in that the locations of the intense electric field in the groove (20) for retaining the glass plate (15) which covers the observation window (10) of said door, comprise a series of bosses (21) serving   to adjust the displacement of this glass plate.   2. Heating apparatus according to claim 1, characterized in that the width of said bosses formed in the groove is about 1/4 of the wavelength at use -   3. Heating apparatus according to claim 1, characterized in that the pitch of the bosses in the groove is   about 1/2 of the wavelength to use.