DE102021211174A1 - Evaporator for a steam processor and household steam processor - Google Patents

Abstract

Evaporator (1) for a steam treatment device, having a receiving space (11) for liquid to be evaporated with a floor-side surface heating (6) which is covered by a cover (2) which has a steam outlet connection (12) and a water passage connection (3), wherein the water passage socket (3) has a first pipe section (3a) running inside the receiving space (11), the mouth of which is below a maximum filling level (F _max ) of the liquid and above the surface heating (6). A household steam treatment appliance has a cooking chamber and an evaporator (1) as described above, the steam outlet connection (12) of the evaporator (1) being fluidically connected to the cooking chamber and the household steam treatment appliance being set up to allow liquid through the water outlet connection piece ( 3) to promote into the receiving space (11) and to promote through the water outlet connector (3) from the receiving space (11).

Description

The invention relates to an evaporator for a steam treatment device, having a receiving space for liquid to be evaporated with a floor-side surface heating, which is covered by a cover, which has a steam outlet connection and a water passage connection. The invention also relates to a household steam treatment appliance, having a cooking chamber and an evaporator, the steam outlet connection piece of the evaporator being fluidically connected to the cooking chamber and the household steam treatment appliance being set up to convey liquid through the water passage connection piece into the receiving space and through the water passage connection piece to promote from the recording room. The invention is particularly advantageously applicable to baking ovens with steam treatment functionality.

DE 43 09 240 A1 discloses an evaporator which is in the form of a flat can, with a base made of unalloyed steel, made corrosion-resistant on its surface by a layer of nickel and heated by tubular heaters. It is kept at an even temperature by a thermostat. The steam is generated by appropriate dosing of the liquid to be evaporated via a pump in the same quantity, in which the evaporation takes place almost immediately on the previously dry evaporator surface.

WO 2012/089469 A1 discloses a cooking device having a cooking chamber in which the food to be cooked is placed, a steam generator having a body and a cover covering the top of the body, an inlet through which water can enter the steam generator, and an outlet, through which the steam generated in the steam generator can escape from the steam generator.

EP 2 298 140 A2 discloses a steam generator for a household appliance with an evaporator chamber to which a connection for the supply of water and at least one connection for the discharge of steam are connected in a flow-conducting manner and with an evaporator surface that can be heated and is arranged at an angle to the horizontal in the installed position, above which an evaporator chamber for the generated steam and in which a steam flow develops in the direction of the steam outlet, the water supply to the evaporator surface being controllable or regulatable via a valve or a pump arranged in the supply line and the water level above the evaporator surface being recorded by means of a level monitoring device and for controlling the Water supply to the evaporator surface is evaluated. In order to design a steam generator for a household appliance with a small overall volume and high heat output or steam output, which is designed for continuous steam generation and in which the heating device is reliably prevented from running dry, the filling level monitoring device is arranged in the area of the vaporizer chamber of the steam generator, in where only a low or no flow intensity of the vapor develops over the evaporator surface.

DE 10 2014 203 537 A1 discloses that an evaporator is provided for a steam treatment appliance, in particular a household appliance, and has a receiving space for liquid to be evaporated with a floor-side surface heating and a steam outlet opening and two electrical contacts exposed in the receiving space for determining a fill level in the receiving space, the surface heating having at least has an unheated zone and at least one electrical contact is arranged above an unheated zone.

DE 10 2014 210 669 A1 discloses an evaporator for a steam treatment device, in particular a household appliance, which has a receiving space for liquid to be evaporated with a floor-side panel heater which has a peripheral side edge, the side edge being convex at least in sections in cross section.

WO 2015/185589 A1 discloses an evaporator for a household appliance. This has a receiving space for liquid to be evaporated with an electric heater and a level sensor for determining the level of the liquid in the receiving space, the level sensor being a non-contact sensor that generates an electromagnetic field in the receiving space and is located on the outside of the receiving space delimiting housing wall is arranged.

DE 10 2015 205 496 A1 discloses a heating element for a household appliance. The heating element has a metallic heating layer, at least one panel heater for heating the heating layer and at least one flat sensor structure located between the heating layer and the panel heater, which are electrically insulated from one another, the at least one sensor structure having at least two flat sensor substructures which are electrically separate from one another and which are at least partially are intertwined and have the respective electrical connections. A liquid heating device for a household appliance has at least one such heating element whose metallic heating layer is provided as a contact surface for a liquid to be heated. A household cooking appliance has at least one such liquid heating device.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art and in particular to provide an economical to produce and efficient evaporator for a steam treatment device with floor-side surface heating, the calcification of which can be particularly effectively reduced with structurally simple means.

This object is solved according to the features of the independent claims. Preferred embodiments can be found in particular in the dependent claims.

The object is achieved by an evaporator for a steam treatment device, having a receiving space for liquid to be evaporated with a floor-side surface heating, which is covered by a cover having a steam outlet connection and a water passage connection, the water passage connection having a first pipe section running inside the receiving space, the mouth of which lies below a maximum filling level of the liquid, in particular with regard to steam generation operation, and above the surface heating.

This evaporator has the advantage that the water passage connector is also suitable for sucking liquid out of the receiving space, e.g. after a steam treatment beforehand or for sucking off cleaning liquid, e.g. decalcifying liquid.

The water outlet socket is compared to one such as in DE 10 2014 203 537 A1 , DE 10 2014 210 669 A1 and WO 2015/185589 A1 disclosed bottom-side water passage nozzle is particularly advantageous if the suction is to be carried out by means of a pump, because insoluble particles floating in the water, in particular lime particles, are then suctioned off with less probability. This is based on the finding that the weight of the particles counteracts entrainment by the suction flow, so that these particles are more likely to remain behind than with a bottom-side arrangement of the water outlet connector, in which the weight of the particles promotes their entrainment through the water outlet connector. The water passage connector according to the invention thus serves as a kind of mechanical separator for small, insoluble particles that cannot be sucked in with the water against the force of gravity. The lower amount of returned particles is in turn advantageous for the service life and function of the pump. The water outlet connector is also advantageous in comparison to a bottom water outlet connector because it avoids a potentially leaky and corrosion-prone connection, typically a welded connection, of the water outlet connector. In addition, a surface heating system with a larger heating surface can advantageously be provided, for example because the area freed up by the omission of the floor-side water outlet socket can be used for laying heating strips and steam can thus be generated more quickly with a higher heating output. Another advantage of the water outlet connector compared to a bottom water outlet connector is that cheaper standard hoses can be used to connect the connector instead of special molded hoses.

The water outlet nozzle can therefore be used both for filling liquid into the receiving space (e.g. for filling fresh water during a steam treatment process of the steamer, for filling fresh water for rinsing the receiving space, for filling cleaning liquid during a cleaning process, e.g. descaling process, etc.) and for Draining or returning liquid from the receiving space (e.g. to return used water after a steam treatment process or rinsing process or to remove cleaning liquid, etc.).

The steam treatment device can be a stand-alone steamer or a cooking device such as an oven and/or a microwave oven with a steamer function.

For a steam generation operation, the receiving space is used to receive water that is brought to the boil by the floor-side surface heating. The resulting steam is discharged from the receiving space through the steam outlet nozzle. The side of the surface heating on the receiving space side represents an evaporator surface. The evaporator surface is in particular at least approximately a flat surface or in particular has an at least approximately flat basic shape.

The liquid to be evaporated can be water with or without additives such as aromatizers, decalcifying agents, etc., but is in principle not limited to this. It is also possible to adjust the heat output of the surface heating so that the liquid is only heated but not evaporated. This can be useful for descaling, for example.

It is a development that the surface heating has a continuous layer of thermally highly conductive and corrosion-resistant material, eg stainless steel or ceramics, on its upper side facing the receiving space. One or more resistance heating tracks are attached to the underside of the layer facing away from the receiving space, possibly via a thin electrically insulating insulating layer, which heat up areas of the layer above it when current is applied. The surface heating can be used, for example, in the same way as in DE 10 2015 205 496 A1 be formed disclosed heating element. It is a further development that the surface heating has several resistance heating tracks that can be powered independently, which has the advantage that the heat output introduced into the surface heating and thus the amount of steam can be varied over a wide range by controlling the individual heating tracks, e.g. with 400 W, 800 W or 1200 W. It is a further development that heating tracks are designed and arranged in such a way that heated and unheated or significantly less heated zones are formed on the evaporator surface.

In a further development, the resistance heating tracks are thick-film heating tracks, e.g. printed thick-film heating tracks. As a result, the surface heating can be produced particularly easily, inexpensively and with high quality and, in addition, has a low overall height, e.g. of only 1 cm to 2 cm, in particular in contrast to the use of tubular heating elements as heating elements. In addition, e.g. in contrast to the use of tubular heating elements, a low intrinsic mass is achieved, which keeps thermal inertia low, whereby the surface heating can be brought up to operating temperature quickly and steam production is accelerated.

It is a further development that the cover forms the side wall and the ceiling of the accommodation space, while the floor is essentially formed by the surface heating. A further development is that the surface heating is arranged in a base piece of the evaporator on which the cover can be placed, e.g. by latching, in particular on an edge or flange of the base piece running laterally next to the surface heating. For improved vapor sealing, there can be a seal, in particular a circumferential seal, for example a silicone seal, between the cover and the base piece. In particular, electrical connections for the at least one heating track run through the base piece. In a further development, the base piece has at least one fastening means for fastening the evaporator, e.g. at least one foot. It is a further development that the cover and the base are made of plastic.

In a further development, the steam outlet connection is arranged in a side wall of the lid near the ceiling. The resulting high distance to the water boiling in the receiving space means that the water droplets contained in the steam (e.g. so-called "spitters" produced by the boiling movement) are less likely to get into the steam outlet connection than with a lower arrangement. The lateral arrangement in the side wall also serves the same purpose, since the spitters primarily shoot upwards, and thus past the mouth of the steam outlet nozzle into the receiving space. In a further development, the steam outlet connection is a substantially horizontally aligned, tubular connection that protrudes from the side wall of the lid on the outside. A steam line can be connected to the steam outlet connection, e.g. a hose, the other end of which leads to the cooking chamber.

The fact that the water passage connector has a first pipe section running inside the receiving space includes, in particular, that the first pipe section merges into a second pipe section, which leads to the outside through the cover. The second pipe section can be connected to a liquid line on a component of the steam cooking appliance, e.g. to a pump or a valve, with its external socket.

In a further development, the first pipe section and the second pipe section are arranged at an angle to one another. In particular, the second tube section can be arranged on the side wall of the cover and aligned at least essentially horizontally, which enables a particularly space-saving connection of the liquid line.

The fact that the mouth of the first pipe section is below a maximum water fill level means that liquid in the receiving space can be returned, in particular sucked off, through the water outlet connector at least up to the height of the mouth. The deeper the mouth is, the smaller the amount of residual water remaining in the receiving space after being returned.

The fact that the mouth of the first pipe section is arranged above the surface heating, i.e. at a distance from the surface heating and therefore does not come into contact with the surface heating, has the advantage that the first pipe section is not damaged by direct heat conduction from the surface heating. The first pipe connection can therefore be made of plastic without any problems.

In one configuration, the first pipe section is at a vertical distance of between 1 mm and 5 mm, in particular between 1 mm and 2 mm, from the surface heating. In this way, the advantage is achieved that the flow area of the orifice towards the entrance of the orifice is kept small and thus the probability of particles being fed back into the water passage channel is further reduced. It has been shown that a distance of between 1 mm and 2 mm results in a particularly significant reduction in the amount of particles. Another advantage is that a sufficient thermal distance to the surface heating is achieved and the amount of residual water can be kept particularly low.

It is an advantageous development for reducing the amount of residual water that the surface heating or its evaporator surface is aligned slightly obliquely or at an angle to the horizontal and the mouth of the first pipe section is arranged above a lowest area of the surface heating.

In one configuration, a mouth-side edge of the first pipe section has a plurality of incisions distributed in the circumferential direction. This has the advantage that, in the event that the opening of the first pipe section should be covered at the end by a flat piece of particle, a flow of water through the incisions can be maintained. For example, the incisions may be in the form of rectangular indentations or notches. The edge can also have a wavy shape.

In one embodiment, the first pipe section is aligned vertically, which results in the advantage of a particularly short length of the first pipe section and thus, for example, a saving in material compared to an inclined arrangement—which is also possible in principle.

In one embodiment, surface heating or its evaporator surface has at least one unheated zone or unheated surface area and the opening of the first tube section is arranged above an unheated zone. This allows the opening of the first tube section to be at a particularly small distance from the evaporator surface.

In one configuration, an opening of the steam outlet connection piece into the receiving space is arranged above an unheated zone. The advantage is thus achieved that the possibility of the water droplets produced by the boiling being entrained with the steam flow through the steam outlet nozzle is reduced even further. This increases the vapor quality. The fewer water droplets there are in the stream of steam, the greater the certainty that the cooking process will succeed.

In one configuration, the evaporator also has a scale filter which is accommodated in the receiving space and is arranged at a lateral distance from the mouth of the steam outlet connection. Surprisingly, it has been shown that the water content of the steam at the steam outlet connector is also reduced by dispensing with the limescale filter below or immediately in front of the mouth of the steam outlet connector. The fact that the limescale filter is arranged at a lateral distance from the mouth of the steam outlet connection means, in particular, that the limescale filter has a noticeable lateral distance to the mouth when viewed from above. In a further development, this distance is at least 2 cm, advantageously at least 5 cm.

It is a further development that the evaporator is equipped with a level sensor. This can be used, for example, by the household steam treatment device in such a way that, during steam treatment operation, the receiving space is refilled with fresh water through the water outlet connector when the filling level is low, until the height of the filling level sensor is reached.

In a further development, the evaporator is equipped with a calcification detection device, by means of which a degree of calcification of the water in the receiving space and/or a thickness of a layer of lime deposited on the surface heating and/or on the inner wall of the lid can be determined at least approximately. In this way, for example, a point in time for activating a cleaning process, in particular a descaling process, can be determined.

The object is also achieved by a household steam treatment device, having a cooking chamber and an evaporator as described above, the steam outlet connection of the evaporator being fluidically connected to the cooking chamber, so that steam can be routed through the steam outlet connection into the cooking chamber, and the household Steam treatment device is at least set up to convey liquid through the water passage connection piece into the receiving space, e.g. by gravity of the liquid or a pump.

The domestic steam treatment appliance can be made analogous to the evaporator and vice versa and gives at least the same advantages.

For example, it is an embodiment that the household steam treatment device is set up to also drain liquid through the water to promote passage nozzle from the receiving space, for example by gravity of the liquid or a pump.

If the household steam treatment appliance has a pump for conveying the liquid into and out of the receiving space, this can either change its direction of conveyance or a similarly acting valve system can be interposed between the pump and the water passage connection.

It is a further development that after each steam treatment or steam cooking process, used water that is still in the receiving space is returned through the water outlet connector. This reduces the likelihood of a microbial film forming in the receiving space.

In one configuration, the household steam treatment appliance is set up to convey cleaning liquid through the water passage connection piece into the receiving space and to convey it out of the receiving space through the water passage connection piece. This can be done, for example, as part of an independent cleaning process.

• 1 zeigt in Ansicht von schräg oben einen Verdampfer mit halbtransparent dargestelltem Deckel; und
• 2 zeigt den Verdampfer als Schnittdarstellung in Seitenansicht durch einen Wasserdurchlassstutzen.

The characteristics, features and advantages of this invention described above, and the manner in which they are achieved, will become clearer and more clearly understood in connection with the following schematic description of an exemplary embodiment, which will be explained in more detail in connection with the drawings.

• 1 shows an evaporator with a cover that is shown semi-transparent in a view at an angle from above; and
• 2 shows the evaporator as a sectional view in a side view through a water passage connection.

1 shows an oblique view from above of an evaporator 1 with a semi-transparent cover 2. 2 shows the evaporator 1 as a sectional representation in a side view through a water passage connector 3 leading through the cover 2.

The evaporator 1 has a base part 4 made of plastic, which has a flat, bowl-shaped carrier area 5 for receiving a plate-shaped or disk-shaped surface heating 6 on the upper side. In a top view, the support area 5 and the surface heating 6 have, purely by way of example, the shape of a rounded rectangle, with the support area protruding laterally all around the surface heating 6 and there an attachment area for the cover 2 or a circumferential seal 7 present between the cover 2 and the support area 5 provides.

The carrier area 5 also has, for example, at least one fastening means in the form of at least one foot 8 that can be screwed on, for example, openings for passing through electrical connections 9 of at least one heating track of the surface heating 6, etc.

The lower edge of the cover 2 can be placed directly or, advantageously for vapor tightness, via the seal 7 on the attachment area of the base part 4 and can be fastened to the base part 4, here: via a plurality of snap-in connections 10 distributed in the circumferential direction. When the cover 2 is in place, together with the surface heating 6, it forms a receiving space 11 for liquid heated by the surface heating 6. More precisely, the surface heating 6 forms the bottom of the receiving space 11, while the cover 2 forms the peripheral side wall and the ceiling of the receiving space 11.

In the side wall of the cover 2, a steam outlet connection 12 is guided horizontally outwards immediately below the cover. The steam outlet nozzle 12 serves to release steam, which has been generated by boiling water by means of the surface heating 6, to a cooking chamber (o. Fig.) of a household steamer, in particular an oven with steamer function (o. Fig.). The arrangement chosen reduces the likelihood of water droplets entering the steam outlet nozzle 12 . The steam outlet nozzle 12 opens into an area of the receiving space 11 which is above an unheated zone of the surface heating 6, which further reduces the likelihood of water droplets, e.g. spitter, getting into the steam outlet nozzle 12 with the steam.

Above this unheated zone there is also a sensor element 13 of a fill level sensor, which has the advantage that when the heating track of the surface heating 6 is energized, the water surface is calmer there than above a heated zone and the fill level can consequently be determined more precisely. This filling level sensor can be used to detect whether liquid in the receiving space 11 has reached the sensor element 13 or not. If this is not the case, water can be refilled through the water outlet socket, for example. If this is the case, the supply of water can be stopped, for example. The sensor element 13 of the level sensor thus determines a maximum level F _max of the liquid in the receiving space 11.

The water passage connector 3 has two straight tubular sections, namely a horizontal second pipe section 3b which protrudes through the side wall of the cover 2 above the maximum filling level F _max and which merges in the receiving space 11 into a vertical first pipe section 3a angled at 90° thereto. The first pipe section 3a opens into the receiving space 11 below the maximum filling level F _max , but above the top evaporator surface of the surface heating 6, in particular at a distance d of approximately 1 mm to 2 mm above the evaporator surface. The mouth-side edge of the first tube section 3a has a plurality of rectangular incisions 14 (also referred to as “loopholes”) distributed along its circumferential direction. For particularly complete liquid suction, the surface heating 6 or its upper-side evaporator surface is slightly inclined in such a way that the mouth of the first pipe section 3a is located above a comparatively low-lying area of the surface heating 6 .

A limescale filter 15, _e.g serves as a storage place for lime instead of the evaporator surface.

The cover 2 can be a component manufactured in one piece with its water passage connection 3 and its steam outlet connection 12, e.g. an injection molded component.

For a steam treatment process, water can be conveyed, e.g. pumped, through the water outlet connection 3 into the receiving space 11 and brought to the boil by the surface heating 6, with the resulting steam being discharged through the steam outlet connection 12 into the cooking space. At the end of the steam treatment process, there is often still comparatively high calcareous used water in the receiving space 11. In order to reduce the likelihood of limescale deposits and the formation of microbial films, the used water, possibly with the exception of a small remainder, can be sucked out through the water flow connection 3, e.g. to be pumped.

For descaling the evaporator 1, descaling liquid can be conveyed, e.g. pumped, through the water passage connection 3 into the receiving space 11 (up to the maximum fill level F _max of a steam treatment process or even higher) and heated by the surface heating 6, if necessary even brought to a boil become. The decalcifying liquid is left in the receiving space 11 for a certain period of time and is then sucked out again through the water outlet connector 3, for example pumped out. One or more rinsing processes, for example with water, can follow, in which the water can be heated by the surface heating 6, but does not need to.

Of course, the present invention is not limited to the embodiment shown.

In general, "a", "an" etc. can be understood as a singular or a plural number, in particular in the sense of "at least one" or "one or more" etc., as long as this is not explicitly excluded, e.g. by the expression "exactly a" etc.

A numerical specification can also include exactly the specified number as well as a usual tolerance range, as long as this is not explicitly excluded.

Reference List

1

Evaporator

2

Lid

3

water outlet socket

3a

First pipe section

3b

Second pipe section

4

bottom part

5

carrier area

6

panel heating

7

poetry

8th

Foot

9

Electrical connection

10

snap connection

11

recording room

12

steam outlet nozzle

13

sensor element

14

incision

15

Limescale filter

i.e

Distance

Fmax

Maximum level

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 4309240 A1 [0002]
• WO 2012089469 A1 [0003]
• EP 2298140 A2 [0004]
• DE 102014203537 A1 [0005, 0013]
• DE 102014210669 A1 [0006, 0013]
• WO 2015185589 A1 [0007, 0013]
• DE 102015205496 A1 [0008, 0018]

Claims (10)

Evaporator (1) for a steam treatment device, having a receiving space (11) for liquid to be evaporated with a floor-side surface heating (6) which is covered by a cover (2) which has a steam outlet connection (12) and a water passage connection (3), characterized in that the water passage connector (3) has a first pipe section (3a) running inside the receiving space (11), the mouth of which is below a maximum filling level (F _max ) of the liquid and above the surface heating (6). evaporator (1) after claim 1 , wherein the first pipe section (3a) has a vertical distance (d) between 1 mm and 5 mm, in particular between 1 mm and 2 mm, from the surface heating (6). Evaporator (1) according to one of the preceding claims, wherein a mouth-side edge of the first tube section (3a) has a plurality of incisions (14) distributed in the circumferential direction. Evaporator (1) according to one of the preceding claims, wherein the first tube section (3a) is oriented vertically. Evaporator (1) according to one of the preceding claims, wherein the water passage connector (3) runs through a side wall of the cover (2) and has a horizontally outwardly projecting second pipe section (3b) which merges into the first pipe section (3a). Evaporator (1) according to one of the preceding claims, wherein the surface heating (6) has at least one unheated zone and the mouth of the first tube section (3a) is arranged above an unheated zone. evaporator (1) after claim 6 , wherein a mouth of the steam outlet (12) is arranged in the receiving space (11) above an unheated zone of the surface heating (6). Evaporator (1) according to one of the preceding claims, wherein the evaporator (1) also has a limescale filter (15) accommodated in the receiving space (11) which is arranged laterally spaced from the receiving-side opening of the vapor outlet connection (12). Household steam treatment appliance, having a cooking chamber and an evaporator (1) according to one of the preceding claims, wherein the steam outlet connection (12) of the evaporator (1) is fluidically connected to the cooking chamber and the household steam treatment appliance is set up to allow liquid through the water outlet connection piece (3) to promote into the receiving space (11) and to promote through the water outlet connector (3) from the receiving space (11). household steam treatment device claim 9 , wherein the household steam treatment appliance is set up to convey cleaning liquid through the water outlet socket (3) into the receiving space (11) and through the water outlet socket (3) from the receiving space (11).

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