STEAM GENERATOR FOR A STEAM COOKING APPLIANCE, STEAM COOKING APPLIANCE HAVING A STEAM GENERATOR OF SAID TYPE, AND METHOD FOR GENERATING STEAM

Abstract

A steam generator for a steam cooking appliance having a cooking chamber has steam-generating means, a water supply to the steam-generating means, a cyclone separator for steam generated by the steam-generating means, and a steam outlet from the cyclone separator to the cooking chamber of the steam cooking appliance. The cyclone separator forms an integrated structural unit with the steam-generating means, with a direct entry of steam from the steam-generating means into the cyclone separator and with a direct exit of separated-off water from it into the steam-generating means. The integrated structural unit yields advantages in the production and assembly of the steam generator and installation of the steam cooking appliance as a whole.

Claims

1. Steam generator for a steam cooking appliance having a cooking chamber, having: steam-generating means, a water supply to said steam-generating means, a cyclone separator for steam generated by said steam-generating means, a steam outlet from said cyclone separator to said cooking chamber of said steam cooking appliance, wherein: said cyclone separator forms an integrated structural unit with said steam-generating means, with a direct entry of steam from said steam-generating means into said cyclone separator.

2. Steam generator according to claim 1, wherein a direct exit of separated-off water from said cyclone separator into said steam-generating means is provided without a pump.

3. Steam generator according to claim 1, wherein said cyclone separator is mounted onto the steam-generating means.

4. Steam generator according to claim 3, wherein said cyclone separator is arranged directly above said steam-generating means in a vertical direction.

5. Steam generator according to claim 1, wherein said steam-generating means and said cyclone separator have, as a structural unit, a common external housing.

6. Steam generator according to claim 5, wherein said external housing is divided at least in two with at least an upper housing part and a lower housing part.

7. Steam generator according to claim 6, wherein said lower housing part comprises said steam-generating means, and said upper housing part comprises said cyclone separator.

8. Steam generator according to claim 1, wherein said steam-generating means have a tubular housing which forms a steam-generating chamber.

9. Steam generator according to claim 5, wherein said steam-generating chamber has an externally situated heating means, and wherein said tubular housing of said steam-generating means is a lower housing part of said common external housing.

10. Steam generator according to claim 1, wherein said cyclone separator is composed of plastic and in one piece by being assembled from at least two parts which are non-detachably connected to one another.

11. Steam generator according to claim 1, wherein said steam outlet from said cyclone separator is arranged centrally and is formed so as to run upwards.

12. Steam generator according to claim 1, wherein said cyclone separator has: a cyclone channel which runs at least in sections in arcuate fashion and which serves for separating water steam into both steam and water, at least one water steam inlet for an introduction of water steam from said steam-generating means, arranged therebelow, upwards into said cyclone channel or into said cyclone separator, said steam outlet at an end region of said cyclone channel, said water outlet from said cyclone separator or from said cyclone channel for a discharge of separated-off water downwards into said steam-generating chamber of said steam-generating means.

13. Steam generator according to claim 12, wherein said cyclone channel has a cross-sectional reduction at a starting region situated close to said water steam inlet.

14. Steam generator according to claim 12, wherein said cyclone channel has a cyclone base, wherein said cyclone base runs, in a radially outer region of said cyclone channel, in a plane, wherein a cyclone side wall narrows in spiral fashion, wherein, in a radially inner region of said cyclone separator, a channel depression is provided which extends below a plane of said cyclone base in a radially outer region of said cyclone channel.

15. Steam generator according to claim 14, wherein a height of said channel depression amounts to more than two times a height of said cyclone channel in said radially outer region.

16. Steam generator according to claim 14, wherein said channel depression is of stepped and/or circular form.

17. Steam generator according to claim 14, wherein said channel depression is at least partially conical or funnel-shaped.

18. Steam generator according to claim 14, wherein said channel depression is radially symmetrical about a central axis of the cyclone separator.

19. Steam generator according to claim 14, wherein said steam outlet is arranged centrally with respect to a centre of said channel depression.

20. Steam generator according to claim 19, wherein said steam outlet has a downwardly projecting steam outlet pipe with a lower pipe opening, said lower pipe opening running in a region of said channel depression and below said plane of said cyclone base in said radially outer region of said cyclone channel.

21. Steam generator according to claim 14, wherein, from a lowest point of said channel depression, said water outlet proceeds downwards.

22. Steam generator according to claim 21, wherein said water outlet ends below a plane in which an upper edge of said heating means of said steam-generating means is situated.

23. Steam generator according to claim 14, wherein said channel depression forms a separation region.

24. Steam generator according to claim 1, wherein, in said cyclone separator, there are provided two separate and spaced-apart water steam inlets for an introduction of water steam from said steam-generating means into said cyclone channel, wherein said two water steam inlets are arranged opposite one another with respect to a central axis of said cyclone separator.

25. Steam cooking appliance having a steam generator according to claim 1 and a cooking chamber, wherein a water inlet into said steam-generating means is provided, and steam from said steam outlet of said cyclone separator is conducted into said cooking chamber.

26. Method for generating steam by means of a steam generator according to claim 1 in a steam cooking appliance for operation of said steam cooking appliance, said method having the steps: heating water in order to generate water steam, transferring said water steam directly above said heated water into a cyclone separator, separating off water from said water steam within said cyclone separator by conducting said water steam in an encircling and spirally inwardly narrowing manner, recirculating said separated-off water into said steam-generating means, and discharging said steam from said cyclone separator into a cooking chamber of said steam cooking appliance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Exemplary embodiments of the invention are schematically illustrated in the drawings and will be discussed in more detail below. In the drawings:

[0028] FIG. 1 shows a schematic construction of a steam cooking appliance according to the invention with a steam generator according to the invention for a cooking chamber,

[0029] FIG. 2 shows the steam generator on its own in a vertical section,

[0030] FIG. 3 shows the steam generator, with the upper cover having been cut away, in an oblique view, and

[0031] FIG. 4 shows the steam generator from FIG. 3 in the direct plan view.

DETAILED DESCRIPTION

[0032] FIG. 1 shows a highly simplified illustration of a steam cooking appliance 11 according to the invention with the parts essential to the invention. The steam cooking appliance 11 has a housing 12 with a cooking chamber 14 which is accessible from the right via a door 15. A steam inlet 16 leads into the cooking chamber 14 from above. The steam inlet 16 leads to a steam generator 30 which will be discussed in more detail below. A water outlet from said cooking chamber is possible, but is not relevant here.

[0033] The steam cooking appliance 11 has a controller 18 which controls the operation of the steam generator 30 with regard to both heating and a supply of water. A water tank 20 is connected by means of water lines 21 to the steam generator 30. For a controlled supply of water and a controlled discharge of water, a pump 22 and a valve 24 are provided in the water lines 21, which pump and valve are connected to the controller 18, in a similar manner to a heating means (not illustrated in any more detail here) of the steam generator 30. The pump 22 can pump water from the water tank 20 into the steam generator 30 in a manner controlled by the controller 18, for which purpose the valve 24 is opened. During the evaporation, the valve 24 may remain at least partially closed and be opened only for the replenishment of water. After a generation of steam, or after the end of the operation of the steam cooking appliance 11, the valve 24 can be opened by the controller 18 such that remaining water either flows back from the steam generator 30 into the water tank 20 of its own accord, or is pumped back with assistance from the pump 22 if the pump 22 is designed correspondingly.

[0034] FIGS. 2 to 4 illustrate the steam generator 30 according to the invention in more detail. As shown in FIG. 3, a heating element 36 is applied to the outside in the lower region. Said lower region of the steam generator 30 is situated at an outer side of its housing 31 and is thus part of the abovementioned steam-generating means with a lower housing part 34. In the steam-generating means 33, water is heated by the heating means 36 and is caused to simmer or brought to a boil, such that water steam is generated. Water can be fed, or else discharged, via a water inlet 38 in the base 37 of the steam-generating means 33. Illustrated by dashed lines, with the designation W, is a water level line for normal operation of the steam generator 30, such that the steam-generating means 33 are filled up to approximately said water level line W. For this purpose, use may be made for example of water level sensors of a wide variety of types, which will not be discussed in any more detail here. This may be realized by means of conductivity sensors, capacitive sensors or else temperature sensors on the outer side of the steam-generating means 33. A person skilled in the art can correspondingly find these in the prior art and apply or install them here.

[0035] A cyclone separator 40 is mounted, specifically directly mounted, onto the steam-generating means 33. An outer wall of an upper housing part 41 of the cyclone separator 40 can thus form a direct continuation of the form and cross section of the lower housing part 34. The two housing parts 34 and 41 can thus form an outer housing, as has been discussed in the introduction. This continuation of the contour need not be imperative, but is expedient for good steam guidance within the steam generator 30 and in particular for ensuring a sealing action between the two housing parts. Provision may also be made for an additional cover to be provided over the lower housing part 34 for the purposes of protecting the heating element 36, for example also in order to cover connector plugs or the like.

[0036] A connection of the lower housing part 34 and upper housing part 41 may be realized in a variety of ways. Firstly, this may be realized by adhesive bonding, wherein the lower housing part 34 generally has a shell composed of metal, and a base 37 is possibly composed of plastic. The upper housing part 41 is generally produced from plastic, simply owing to the better mouldability or producibility. The two housing parts 34 and 41 may also be assembled with a seal in between, while for example still being held together by means of clamping parts or the like.

[0037] The cyclone separator 40 with the upper housing part 41 has a cyclone channel 43 that can be seen from FIGS. 2 to 4. Said cyclone channel runs clockwise as viewed from above and is formed between a cyclone base 44, parallel to and spaced apart from which there runs a cover 47. In between, there runs a cyclone partition 45 with the spiral form. It can be seen, in particular from FIG. 4 with the hatching, that a water steam inlet 46 is formed by, as it were, omitting the cyclone base 44, specifically over almost an entire circumference. Accordingly, the water steam inlet 46 has a varying width, or increasing in the flow direction. The cyclone channel 43 that adjoins said water steam inlet extends approximately over one and a half times the circumference, beginning where the water steam inlet 46 ends and the cyclone base 44 begins. The water steam inlet 46 as per the plan view in FIG. 4 could also be divided in two, for example by means of a web parallel to the cyclone base 44 toward the outer wall. Improved strength could be achieved in this way.

[0038] At the top in the cover 47, there is provided a steam outlet 49, which is then led to the steam inlet 16 into the cooking chamber 14 correspondingly to FIG. 1. At the steam outlet 49, there is provided a steam outlet pipe 50, which not only projects upward beyond the cover 47 but also projects downwards. FIG. 2 clearly shows that the steam outlet pipe 50 extends a considerable distance below the plane of the cyclone base 44. This means that water steam that enters and circulates in the cyclone channel 43 cannot escape from the steam generator 30 directly, so to speak, in a lateral direction and upwards through the steam outlet 49. Rather, the water steam must first be conducted downwards to a certain extent in order to then enter the steam outlet pipe 50 from below.

[0039] In this region at the bottom, a channel depression 52 is provided in the cyclone base 44. Said channel depression is, as shown in the plan view of FIG. 4, of circular symmetrical and substantially funnel-shaped form with a straight edge at the top and with a water outlet 55 which adjoins the funnel section 53 in a downward direction, and which in this case is in the form of a short pipe. Said water outlet 55 extends below the water level line W, at least during the normal operation of the steam generator 30. Thus, water steam is prevented from being able to rise directly upwards and emerge from the steam generator 30 through the steam outlet 49. The short water outlet 55 is sufficient in this case, a pump or the like for recycling the water into the steam generator 30 is not necessary.

[0040] As indicated by the arrows of FIG. 4, and as is easily conceivable, during the boiling of water in the steam generator 30, water steam is produced at the bottom in the steam-generating means 33. Said water steam also contains small water droplets, which are entrained. The water steam passes through the water steam inlet 46 in the form of an elongate slot upwards into the cyclone separator 40 or into the cyclone channel 43, and circulates clockwise. Here, it is possible for some of the water droplets to already be centrifuged out of the steam in an outward direction, and to collect on the inner sides of the cyclone partition 45 and on the cyclone base 44, owing to the centrifugal force. By means of a possible slight inclination of the cyclone base 44, water can either flow back downward again through the water steam inlet 46, or else can flow to the channel depression 52 with the water outlet 55. In the channel depression 52, owing to the relatively small radius, the action of the centrifuging of the water droplets is considerably further intensified, as is known from cyclone separators and can also be understood by a person skilled in the art from DE 10 2012 200 289 A1 as cited in the introduction. While the, so to speak, dewatered steam then flows out to the steam outlet 49 through the steam outlet pipe 50, the water, in particular the water that has been separated off in the channel depression 52, flows back downward again into the steam-generating means 33. There are thus no problems or effort involved in the recirculation of said water, and furthermore, the water can be utilized again for evaporation. This is thus one of the advantages of the very compact steam generator, which is formed as an integral structural unit. The further advantage is that, by connection of the two housing parts 34 and 41 and thus of the steam-generating means 33 and of the cyclone separator 40, a permanently sealed connection can be produced, in particular a non-detachable connection. Thus, the steam generator 30 according to the invention requires relatively little space in the steam cooking appliance 11, is very easy to install, and is highly operationally reliable.

[0041] It is evidently expedient for the cyclone separator 40 to be produced from plastic by plastics injection moulding, such that a desired form can be achieved. Here, the cyclone separator 40 may be composed of two parts, such that, for example, the cover 47 together with the steam outlet pipe 50 is a first part, and the rest forms a second part. The outer shell may be integrally formed on said part, or else possibly on the part with the cyclone base 44.