WO1997014270A1

WO1997014270A1 - Microwave oven, especially for a laboratory

Info

Publication number: WO1997014270A1
Application number: PCT/EP1996/004221
Authority: WO
Inventors: Werner Lautenschläger
Original assignee: Mikrowellen-Systeme Mws Gmbh
Priority date: 1995-10-10
Filing date: 1996-09-26
Publication date: 1997-04-17
Also published as: DE19537755A1

Abstract

Microwave oven (1), especially for a laboratory, with a heating chamber (3) surrounded by a housing (2), in which microwave radiations can be introduced and which is accessible via a closable aperture (4a, 42). A microwave sensor (16 to 16d) is arranged in the region of a slot (37) in the housing (2) leading from the heating chamber (3) in such a way that, when microwave radiation exceeding a given value passes in and/or through the slot (37), the sensor (16 to 16d) actuates a warning signal or switches off the microwave supply to the heating chamber (3).

Description

Microwave oven, especially for a laboratory

The invention relates to a microwave oven according to the preamble of claim 1.

A microwave oven enables an object to be heated quickly in its boiler room and has therefore found a wide range of uses, e.g. in kitchens and laboratories. The microwave oven is generally arranged in a holding room for people, and therefore a radiation-proof design of the microwave oven is required in order to protect people from harmful microwave radiation. A known measure is e.g. in providing an access door of a microwave oven with a safety switch so that the microwave exposure of the boiler room can only be switched on when the access door is closed.

In practice, the possibility of microwave radiation passing through gaps in the housing depends on the quality of the processing or the assembly. It cannot be ruled out, therefore, that the devices supplied by the manufacturer may emit a harmful amount of radiation or an amount of radiation that exceeds a certain safety value and therefore poses a health hazard to people at the place where the microwave oven is installed.

A previously described source of danger does not only exist in the area of the lockable access opening, e.g. a door for the heating room of a microwave oven, but also on other openings and passages, e.g. Cable bushings, in the housing. The above-mentioned risk exists in particular when a microwave oven is retrofitted with application-specific additional devices, in many cases it is impossible or difficult to check the tightness of the gaps resulting from the retrofitting, and therefore the gaps resulting from the retrofitting, e.g. in the area of bushings or breakthroughs, a previously described source of danger.

The risk of a radiation quantity exceeding a certain value or a harmful radiation quantity therefore not only exists in the area of a door gap in the housing, but also when a line, in particular a liquid line, penetrates the housing wall. This can be, for example, a liquid line for a cooling medium or a material treatment agent, for example a reagent. During the operation of such a microwave oven, there is a prescribed emission of microwave radiation in the area of the line and / or in the Area of the line leadthrough existing gap if the material present in the line is electrically conductive. In addition, the above-described source of danger may also exist in this area in the area of the gap specified by the area to be carried out.

The invention is based on the object of designing a microwave oven of the type specified at the outset in such a way that an unwanted or inadmissible radiation exit is indicated or prevented.

This object is achieved by the features of claim 1.

In the solution according to the invention, the microwave oven is assigned a monitoring device which reports or prevents the emission of a radiation quantity exceeding a predetermined value from the heating room. In this way, people present in the installation area of the microwave oven are effectively protected, since the source of danger can either be switched off automatically immediately or upon a warning signal.

In addition, the configuration according to the invention is characterized by a simple, small and cost-effective construction, so that a microwave oven with the configuration according to the invention can be inexpensively equipped or retrofitted.

The invention thus offers the user a high standard of security, while a simple and trouble-free and safe function is guaranteed.

The invention relates, according to claim 7, to a microwave oven with special access to the heating chamber, in particular from above, the accessibility being formed by an insertion hole into which a vessel for receiving the material to be heated can be adjusted. With such a configuration, the vessel can also form a closure for the heating chamber, so that, at least in this area, no closure is required for the insertion hole. However, it is advantageous to use an additional closure, e.g. provide a shutter door at another point in the heating chamber, in particular on its front side, so that other material or objects can be entered and removed into the heating chamber through the further access opening formed thereby.

Features are contained in the subclaims which lead to further simple and inexpensive to manufacture designs, small size and reliable function. It is it is possible to provide only one microwave sensor for several radiation hazard sources.

In the following, the experience and further advantages which have been achievable so far are explained in more detail with the aid of preferred exemplary embodiments and drawings. It shows:

1 shows a microwave oven according to the invention with a plurality of removed outer cladding walls in a perspective view;

Fig. 2 shows the vertical partial section II-II in Fig. 1;

3 shows the horizontal partial section πi-LTI in FIG. 1;

Fig. 4 shows an electrical circuit for controlling a microwave generator.

The main parts of the microwave oven 1 are a preferably cuboid housing 2 made of microwave reflecting material, in particular steel, which encloses a heating chamber 3, which can be opened and closed by a door or flap 4 on the front, in the present embodiment at the rear of the Housing 2 arranged microwave generator 5, from which the microwaves are coupled through a coupling opening 6 into the heating chamber 3, and several monitoring devices 7a, 7b, 7c, 7d for monitoring and reporting or display in the area of columns or Durch¬ guides from the heating chamber 3 emerging microwave rays.

The monitoring device 7a is provided in the area of the flap 4 for monitoring the gap or joint between the flap 4 and the housing 2. In the present exemplary embodiment, the flap 4 is articulated on the front in the lower region of the housing 2 by two in particular lower hinges 8 and thus can be closed by folding up and opening by folding down. Opposite the hinges 8, the flap 4 has a handle 9 on its outside for its manual actuation. Opposite the hinges 8, a central or two externally arranged latching elements 11 can be provided, which releasably cooperate with counter-latching elements 12 on the housing 2.

As can be clearly seen from FIG. 2, a recess 14 is preferably arranged in the contact surface 13 between the flap 4 and the housing 2 in the contact area 13 facing away from the hinges 8 in the contact surface 15a on the flap 4 or preferably in the contact surface 15b of the housing 2 . In the recess 14 there is a sensor 16 which passes through an electrical line 17 is connected to the electrical control circuit for the microwave oven 1 and in particular for the MW generator 5. The recess 14 is located at a distance a from the inner end of the existing contact joint 18. This ensures that when the flap 4 is properly closed, only a negligible part of the microwave rays can reach the recess 14. In other words, if the flap 4 is designed or installed or closed correctly, the sensor 16a cannot determine any microwave rays.

If, on the other hand, the flap 4 is incorrectly or poorly installed or closed too poorly, the microwaves pass through the gap in the area of the contact joint 18 to the sensor 16a, which then, in a manner still to be described, gives an optical or acoustic signal by means of a preferably electrical signal Display element activated or turns off the MΛV generator 5.

In the context of the invention, the sensor 16 could also at the outer end of the contact joint 18, e.g. outside of this, be arranged. However, such an arrangement would lead to a larger construction and would also deteriorate the appearance of the microwave oven 1, even if such an outside arrangement of the sensor 16 were covered by a screen or the like. In contrast, in the present arrangement the sensor 16 is not only concealed and not visible from the outside, but due to its recessed arrangement it also leads to a small construction. The recess 14 forms a free space 21, which enables the arrangement of the sensor 16a on the contact joint 18.

In the area of the other sides of the housing 2, it is advantageous to provide a common free space 21 as a recess 14 for one or more passages or gaps provided on the side, through which microwave rays emerge from the heating chamber 3 and reach the free space 21 can. A plurality of bushings or gaps can open into the female space 21, only one sensor 16b arranged in the free space 21 being required in order to determine the microwave beams coming from one or more bushings or gaps into the free space 21.

According to an exemplary embodiment shown in FIG. 1, a free space 21a, 21b, for example extending over the entire side, can be provided on one or both sides of the housing 2, each of which has an inner and preferably also an outer side wall 22a, 22b, 23a, 23b is limited. These can be inner and outer cladding sheets, of which the outer cladding sheet 23a, 23b is shown disassembled in FIG. 1 in order to allow an insight into the free space 21a. By the and / or the free spaces 21a, 21b extend one or more supply and / or discharge lines 24, 25, which extend to or from a container 26, which is adjustable through the access opening 4a into the heating chamber 3 and the reception of one with Microwave radiation serves directly or indirectly heatable solid or liquid material. This can be, for example, a sample material that is to be digested, dried, extracted or distilled under the influence of heat. The container 26 consists of a pot-shaped lower part 26a and a cover 26b, which may be pressure-tightly connectable therethrough, through which the lines 24, 25 extend. The line 25 can be, for example, a discharge line which extends to a pump 27 arranged outside the housing 2, by means of which vapors are drawn off from the container 26 and conveyed to a condenser 28, from which they arrive at a condensate collection device 29 . The line 24 can be, for example, a supply line for a gas (purge gas) and / or a liquid which the material to be treated itself or as an aid, for. B. a reagent to promote the treatment of the material to be treated in the container. In the present embodiment, a pump 31 is also provided outside the housing 2, by means of which a aforementioned liquid can be conveyed from a storage container 32 into the container 26.

In order to achieve a purging effect in the container 26 by means of the discharge line 25, it is advantageous to provide a gas or air supply line by means of which a purging effect is achieved when the container 26 is suctioned off. In the present embodiment, the supply line 25 also serves to supply the gas, e.g. Inert gas, or air through a line branch 33, in which a preferably adjustable valve 35 can be arranged.

The lines 24, 25 described above are known per se, see e.g. B. WO 93/22650. To avoid repetition, reference is made to this document in its entirety. Instead of arranging only one container 26 in the heating chamber 3, a plurality of containers can also be arranged therein, e.g. be held on a swivel or rotary rotor, as can also be gathered from the aforementioned publication, see in particular FIG. 6.

The lines 24, 25 extend through bushings 20 or holes 36 in the side walls 22a, 22b, 23a, 23b. As a result, there are 36 columns 37 at the edge of the holes, through which, if they exceed a certain size, microwave radiation from the heating chamber 3 can first pass into the respective free space 21a, 21b and then also into the environment. The columns 37 could be Screwed seals are sealed, however, this is both manufacturing and assembly complex and therefore expensive. Another measure could be to form such a passage through a sleeve which is dimensioned so long that the microwaves in the area of the gap extending in the sleeve, so to speak, "dead reflect". However, such a measure is ineffective if in A means of electrically conductive material is present in the associated line 24, 25. In such a case, the means forms a so-called center conductor, so that microwave radiation also comes from such a passage into the associated free space 21a, 21b and then also in The environment escapes, since when using a microwave oven 1 it cannot be guaranteed that electrically conductive means are conveyed through the lines 24, 25, a source of danger is predetermined.

In the embodiment according to the invention, on the other hand, a sensor 16b is provided in each of the free spaces 21a, 21b. on account of a gap 37 based on a manufacturing or assembly error and microwaves entering the free space 21a, 21b, the display element is activated or the microwave application of the heating chamber 3 is switched off.

A space designated by 21c can also be arranged on the upper side of the housing 2 behind an inner and preferably between an outer upper wall 41a, 41b delimiting it to the outside, a sensor 16c also being arranged therein, in order to e.g. Monitor column in the area of implementations in the sense described above.

However, this free space 21c is part of a special embodiment of the microwave oven 1. In this embodiment, a receiving hole 42 is provided on the upper side of the housing 2, into which a container 43 can be inserted, which is used to receive the heating chamber 3 by means of the Microwave radiation is used indirectly or directly to be heated materials. This material can be one of the materials described above for inclusion in the container 26.

The container 43 also consists of a pot-shaped container lower part 43a and a cover 43b which can be connected to it in a pressure-tight manner. A holding device 44 for the container 3 is assigned in the receiving hole 42, which holds the container 3 in the inserted position in such a way that the lower container part 43a projects into the heating chamber 3 and can be acted upon by the microwave radiation in the heating mode. Such a holding device 44 can be formed in that the container 43 rests on the edge of the receiving hole 42 with a shoulder surface 44a arranged on its lower part 43a or on its cover 43b. If the cover 43b can be firmly connected to the lower part 43a, then the Cover 43b form shoulder surface 44a. The lower container part 43a and possibly also the lid 43b are made of microwaveable or partially permeable material, in particular plastic, glass or quartz, so that the microwaves radiation can get into the lower part 43a. However, a special cover element 45 made of micro-reflecting material is required to cover the receiving hole 42 or the container 43 and thus to prevent the passage of the microwave radiation upwards. This can be done by an upper-side housing cover 46, which is connected to the housing 2, for example, on the rear of the housing 2 by a swivel joint 47. However, it is also possible and advantageous to form the cover 43b as a cover element 45 made of microwave-reflecting material, for example metal, in particular stainless steel, it being advantageous in this case to arrange the cover 43b on the Edge of the receiving hole 42 rests to cover the gap 37 predetermined by the existing passage for the container 43. In the present embodiment, the lid 43a is hat-shaped and has an internal thread on its inner wall, with which it is screwed onto an external thread at the upper end of the container lower part 43a.

In the present embodiment, the housing cover 46 is additionally provided for the outer limitation of the free space 21c.

By means of the sensor 16c provided in the free space 21c, microwave radiation emerging from the heating chamber 3 can be determined through the gap 37 and signaled or switched off in the above-described sense.

Depending on the use, the container 43 can also be provided with at least one of the lines 24, 25 for supplying and / or discharging the material to be treated or the media promoting the treatment, as in the exemplary embodiment described above, such as it is hinted at. In order to avoid repetitions, the supply lines 24 and / or 25 with the associated units such as pumps and the like are referred to in full. The gaps 37 present in the associated walls, in particular in the upper region of the outer side wall 21b in the region of the associated bushings 20, can also be monitored by the sensor 16c in the sense described above. A sensor 16d can also be provided in the associated free space 21c especially for this purpose or in addition to the sensor 16c for the respective or joint monitoring. As FIG. 4 shows, the sensor or sensors 16a to 16d can be arranged in such a way that they interrupt the energy supply to the generator 5 with associated switches 5a to 5d in the sense of a series connection.

It is advantageous to provide a further display device 48 which indicates which of the available sensors has responded and at which point the radiation leakage has taken place. In the case of a microwave oven 1 which is at least partially program-controlled by means of a computer 49 with a monitor 51 and keyboard 52, the monitor 51 on which the location of the leak or the associated sensor is displayed can be used to display the leak point. Control and signal lines are indicated by reference number 53.

In FIG. 1, the supply and / or discharge lines 24, 25 of the container 43 are connected to the described supply and discharge devices. It is possible within the scope of the invention to assign own feed and / or discharge devices to the container 43 or to only assign the latter to the container 43.

Claims

EXPECTATIONS

1. Microwave oven (1), in particular for a laboratory, with a heating chamber (3) surrounded by a housing (2) into which microwaves can be coupled, and which is accessible through a closable access opening (4a, 42), characterized in that a microwave sensor (16 to 16d) is arranged in the area of a gap (18; 37) of the housing (2) emanating from the heating chamber (3) in such a way that upon entry and / or passage of a microwave radiation exceeding a certain value into or through the Gap (18; 37) the sensor (16 to 16d) activates the emission of a warning signal or switches off the microwaves exposure to the heating chamber (3).

2. Microwave oven according to claim 1, characterized in that the sensor (16 to 16d) is arranged in a position hidden by a view from the outside, in particular from the front of the microwave oven (1).

3. A microwave oven according to claim 1 or 2, characterized in that the sensor (16 to 16d) is arranged in a free space (14, 21 to 21c) arranged within the length range of the gap (18, 37, 37a).

4. Microwave oven according to claim 3, characterized in that one or more, arranged on the circumference of the access opening (4a)

Sensors (16a) for determining microwave radiation are arranged in the gap (18) of the closure element (4), which is preferably formed by a door or flap, for the access opening (4a).

5. Microwave oven according to one of the preceding claims, characterized in that one or more gaps (37) open into a common free space (21 to 21c) and one or more sensors (16b to 16d) are arranged in the free space.

6. Microwave oven according to one of the preceding claims, characterized in that in the region of at least one side or the top of the housing (2) preferably a free space (21 to 21c) extending over the entire region of this side. is provided and the column or columns (37) are, for example, parts of the line bushings (20) penetrating the associated free space.

7. Microwave oven (1), in particular for a laboratory, with a heating chamber (3) surrounded by a housing (2), into which microwaves can be coupled, and which is accessible through a closable access opening (42) which is located in a heating chamber ( 3) delimiting wall (41a) of the housing (2), at least one container (43) being provided which can be inserted into the access opening (42) and is held in the inserted position by a holding device (44), at least the Part (43a) of the container (43) protruding into the access opening (42) consists of microwave-permeable or partially permeable material, and a closure element (45, 46) is provided for covering the access opening (42) against the escape of microwave radiation.

In that the wall (41a) of the access opening (42) containing a is 8. The microwave oven according to claim 7, characterized in that the heating chamber (3) to ^'top limiting wall (41a).

9. Microwave oven according to one of the preceding claims, characterized in that the wall (41a) containing the access opening (42) is arranged in the upper region of the housing (2).

10. Microwave oven according to one of the preceding claims, characterized in that the wall (41a) containing the access opening (42) is arranged at a downward distance from the top of the housing (2).

11. Microwave oven according to one of the preceding claims, characterized in that the wall (41a) containing the access opening (42) delimits a free space (21c) inwards.

12. Microwave oven according to one of the preceding claims, characterized in that the free space (21a, 21b, 21c) extends substantially over the entire surface of the associated side of the housing (2).

13. Microwave oven according to one of the preceding claims, characterized in that the closure element (4) is built through a door or a cover (46) for the free space (21c), which preferably has at least one of its edges with at least one swivel joint (47) the housing (2) is connected.

14. Microwave oven according to one of the preceding claims, characterized in that the container (43) can be closed by a cover (43b, 45), in particular a screw cover.

15. Microwave oven according to one of the preceding claims, characterized in that the closure element for the access opening (42) is built through the lid (45) of the container (43).

16. Microwave oven according to one of the preceding claims, characterized in that the container (43) with a flange (44) or with the lid (45) rests on the edge of the access opening (42).

17. Microwave oven according to one of the preceding claims, characterized in that one or more supply and / or discharge lines (24, 25) through a respective associated wall bushing (20) in the free space (21a, 21b, 21c) and further in the Containers (26; 43) extend, preferably through the lid (43b) thereof, and that one or more sensors are provided in the free space (21a, 21b, 21c) for determining microwave radiation.