WO2023126099A1 - Cooking appliance having an evaporator, and method for operation thereof - Google Patents

Abstract

The invention relates to a cooking appliance (1) comprising - a muffle (2) which has a frontal loading opening (3); - an impact wall (6) which is located in front of a rear wall (5) of the muffle at a distance therefrom and which delimits a rear of a cooking chamber (7) and forms a laterally open heating chamber together with the rear wall of the muffle; - an axial fan (9), the fan impellers (10) of which are located in the heating chamber; - an annular heating body which is located in the heating chamber; - a channel (14) which is formed in the impact wall (6), does not widen on the cooking-chamber side, and laterally surrounds the fan impellers (10) at least partially; and - an evaporator (18) which is arranged outside the muffle and the vapour side of which is connected to a vapour inlet (10) that opens into the heating chamber, wherein the cooking appliance (1), in an SHS mode, is designed to operate the fan impellers in a first direction of rotation (R1) in such a way that fluid is sucked out of the cooking chamber through the lateral opening in the heating chamber, flows via the activated annular heating body and is then blown back into the heating chamber through the channel, and to at least temporarily operate the evaporator (18) in the process, and, in at least one other mode, is designed to operate the fan impellers in a second, opposite direction of rotation.

Description

Cooking device with an evaporator and method for operating the same

The invention relates to a cooking appliance, in particular a household cooking appliance, having a muffle with a loading opening on the front, a baffle wall arranged at a distance in front of a rear wall of the muffle, which delimits a rear side of a cooking chamber and forms a heating chamber with the rear wall of the muffle, an axial fan, the fan wheels of which are arranged in the heating chamber, a ring heater which is arranged in the heating chamber, a flow opening formed in the baffle and an evaporator arranged outside the muffle, the steam side of which is fluidically connected to a steam inlet opening into the heating chamber. The invention also relates to a corresponding method. The invention can be applied particularly advantageously to baking ovens with an additional SHS function.

US 2013255655 A1 discloses an oven having an interior defined by a plurality of side walls, a duct and a fan. The duct is in fluid communication with a vent opening in at least one of the sidewalls and a supply of ambient air outside the oven cavity. The fan is in fluid communication with the duct and forces ambient air to enter the cooking cavity through the vent.

CA 2446494 A1 discloses an accelerated cooking function for use in an oven having a cavity. The oven includes a forced air convection system with an electronic control unit, a variable speed bi-directional fan motor and a directional ventilated cover plate. The device operates in at least three modes consisting of a convection mode, a radiant baking mode and a self-cleaning mode. In convection mode, the controller operates the fan motor in a first direction at a speed dependent on a selected cooking process, directing different airflows into different areas of the oven cavity. During radiant cooking mode, the controller operates the fan motor in reverse to create an even cooking environment. In the self-cleaning mode, strong air currents are directed into the cooking chamber and, in combination with an upper grill element, carry out a pyrolytic cleaning process. EP 2 917 645 A1 discloses a baffle for an oven. This includes a flat portion having a first surface facing a cooking cavity of an oven and a second surface which may face a fan of the oven; the flat portion also having an opening for air passage; a frusto-conical body attached to the second surface at the perimeter of the opening and having a plurality of holes; and a deflector disposed on the frusto-conical body opposite the flat portion.

EP 1 107 650 A2 relates to a convection fan control method of a microwave oven capable of changing the discharge direction of air heated by a heater toward a heating object by controlling the rotating direction of a convection fan in accordance with types of dishes with a cooking top becomes.

EP 1 109 425 A2 discloses an oven with a cooking chamber in which food is to be cooked, a heating chamber arranged above the cooking chamber, an axial fan arranged in the heating chamber for generating a downward air flow, and a heater arranged outside the axial flow fan , which is designed to generate high-temperature heat. A convection plate is arranged between the axial fan and the heater. The convection plate serves to control a flow of air circulating inside the electronic range to effectively blow the heat generated by the heater into the cavity during an operation of the axial fan, thereby performing a repeated operation of introducing the flow of air downward into the cavity and then of moving the air flow upwards along a side wall of the cavity. In this oven, food placed in the cavity is heated using reflection heat generated by the convection plates and convection air generated by the axial fan.

DE 7247152 U discloses a cooker with circulation of a stream of hot air by a fan in a heating chamber that can be closed from the outside for the preparation of roasting or baked goods, with the fan forming the end of an air shaft arranged at the rear of the heating chamber, on which an air shaft located above the heating chamber and with this Air extraction duct fluidically connected by openings is connected and the fan is assigned a heated air flow for the heating room dividing grid.

EP 2 993 416 A2 discloses a cooking appliance in which superheated steam can be used during a cooking process. The cooking apparatus supplies superheated steam while food is being cooked, and comprises: a main body whose front side is opened and in which a cooking space is arranged; a heating chamber disposed in the main body to communicate with the cooking cavity; a steam generator arranged to generate steam that is sprayed into the heating chamber; and a convection heater disposed in the heating chamber to heat the heating chamber and the cooking space. The convection heater heats the steam emitted from the steam generator, and the steam emitted from the steam generator is sprayed into the heating chamber in superheated steam state and supplied to the cooking cavity.

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 improved possibility of directing superheated steam into a cooking chamber of a cooking appliance.

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 a cooking appliance having a muffle with a loading opening on the front, a baffle wall arranged at a distance in front of a rear wall of the muffle, which delimits a rear side of a cooking chamber and forms a laterally open heating chamber with the rear wall of the muffle, an axial fan whose fan wheels are in the are arranged in the heating chamber, a heating element (hereinafter referred to as "ring heating element" without restriction of generality), which is arranged in the heating chamber, a flow opening formed in the baffle in the form of a channel that protrudes on the cooking chamber side and does not widen in the direction of the cooking chamber, which surrounding fan wheels on the side, and an evaporator arranged outside the muffle, the steam side of which is fluidically connected to a steam inlet opening into the heating chamber, wherein the cooking appliance is set up in at least one steam treatment operating mode to operate the fan wheels in a first direction of rotation in such a way that gaseous fluid is sucked out of the cooking chamber through the side opening of the heating chamber, flows over the activated annular heating element and then back in through the flow opening is blown into the cooking chamber, and is set up to operate the evaporator at least temporarily, is set up in at least one other operating mode to operate the fan wheels in a second direction of rotation opposite to the first direction of rotation.

This cooking appliance has the advantage that in the steam treatment operating mode, steam introduced into the muffle can be blown through the channel in a targeted manner, i.e. with a defined steam flow, and at high speed onto a specific surface or into a specific volume of the cooking chamber. This makes it possible to direct a flow of steam with a particularly high mass flow directly over the surface or into the volume of the food to be cooked in the muffle. This in turn can shorten the cooking time of this item to be cooked. Without this channel, which does not widen, the vapor flow would disadvantageously fan out even more immediately after passing through the baffle. In addition, the protrusion of the channel into the cooking chamber prevents an undesired backflow of gaseous fluid into the heating chamber at the edge of the flow opening or the channel.

Another advantage is that superheated steam (also known as dry steam or "super-heated steam", SHS) can be generated by the annular heating element at a high temperature, so that the food to be cooked in the cooking chamber can be treated with it. A steam treatment mode with superheated steam will also be referred to below as "SHS mode". This is particularly advantageous in connection with the directed steam flow at high speed, in order to also enable applications that traditionally cannot be satisfactorily implemented in the oven, eg browning steaks. There is advantageously no need for separate heating elements inside the muffle, which are provided primarily or only for generating superheated steam. In a further development, superheated steam with a temperature of up to approx. 600° C. can be generated. Another advantage is that by reversing the direction of rotation of the fan wheels, in addition to the steam treatment function, classic circulating air and hot air operation can still be carried out, which is particularly suitable for even browning of food on several levels.

Because the steam inlet opens into the heating chamber, when the evaporator is in operation, the steam generated by it and flowing into the heating chamber is sucked in by the fan wheels rotating in the first direction of rotation and blown into the cooking chamber. In the heating space, this steam is thus mixed with the gaseous fluid drawn in from the cooking space, and this mixture is subsequently blown through the duct into the cooking space. When the evaporator is not in operation, only the gaseous fluid in the cooking chamber is circulated, with the activated ring heater compensating for heat losses in order to keep the fluid at the target temperature, in particular at a temperature above the boiling point of water, so that this fluid then superheated steam. However, the direction of flow remains the same, so that the circulating fluid is also blown through the channel at high speed in a targeted manner into specific spatial areas of the cooking chamber.

It is a development that the cooking appliance is a domestic cooking appliance.

In a further development, the cooking appliance is an oven and/or a microwave appliance with an additional, optionally switchable steam generation function (“added steam”). It is therefore possible for the cooking chamber to be assigned one or more electrically operated radiant heaters such as a bottom heating element, a top heating element, a grill heating element, etc. and/or a microwave generating unit for introducing microwave energy into the cooking chamber. If the steam generation function is not used, the operating modes known from conventional ovens and/or microwave ovens can be used.

The loading opening on the front of the muffle (which is often also referred to as the baking tube) can be closed by means of a door, which can usually be pivoted. The baffle divides the muffle on the one hand into a cooking chamber between the loading opening or door and baffle wall for accommodating the food to be cooked and on the other hand into the heating chamber. In particular, the baffle wall is aligned parallel to the rear wall of the muffle.

In a further development, the heating chamber along the edge of the baffle wall forms a lateral, in particular laterally circumferential, opening towards the cooking chamber when viewed from the front through the charging opening.

The fan wheels are driven via a shaft which is guided in particular perpendicularly through the rear wall of the muffle and which in turn is driven by a fan motor arranged outside the muffle. The direction of rotation of the fan wheels can be reversed, e.g. by reversing the direction of rotation of the motor (bidirectional fan motor, for example, can be implemented as a BLDC motor whose direction of rotation is reversed by changing the electrical control), by means of a gearbox arranged between the motor and fan wheels, etc. The level of the The fan wheels are in particular aligned parallel to the rear wall.

The fact that the fan is an axial fan includes, in particular, that gaseous fluid (i.e. air or vapours, with or without steam) is sucked in in the area of one end face and blown out at the other end face. In the first direction of rotation, the fluid is sucked out of the heating chamber through the rear end and blown into the cooking chamber through the front end. In the second direction of rotation, the fluid is sucked out of the cooking chamber through the front end and blown into the heating chamber through the rear end.

In particular, the ring heater has a lateral extent (in front view) that is less than the lateral extent of the baffle. The ring heater is in particular an electrically operated resistance heater, for example a tubular heater. The ring heater can be a single-circuit or multi-circuit heater. The fact that the ring heater is activated means in particular that it is heated, for example by targeted energization. An activated ring heater can, for example, be supplied with current continuously or in cycles. In a further development, the channel is a channel that is ring-shaped in front view, in particular a channel that is in the form of a circular ring. The fact that the channel is a channel that does not widen includes in particular that the diameter of the channel does not increase in the direction from back to front or from the rear wall in the direction of the cooking space. The size of the extension of the channel in the direction from the rear wall into the cooking space is also referred to below as the “depth” of the channel.

The fact that the duct laterally surrounds the fan wheels (when viewed from the front) has the effect that when the fan wheels blow a fluid flow through the duct, this fluid flow flows almost completely through the duct and pressure losses are avoided. In addition, this arrangement is particularly compact, and a separate housing on the side can be dispensed with. The fact that the duct laterally surrounds the fan wheels can include the duct laterally surrounding the fan wheels in the direction along the axis of rotation completely or only in sections. In particular, this can also be expressed in such a way that the fan wheels, starting from the heating room, are fully or partially immersed in the duct.

The evaporator is designed to boil water supplied to it—for example from a water tank or from a fresh water connection—by means of at least one heating element. The resulting wet steam, which may also contain water droplets, is discharged on its steam side and, driven by its steam pressure, flows through the steam inlet of the muffle into the boiler room.

The steam treatment operating mode is an operating mode in which wet steam escaping through the steam inlet is sucked in by the fan wheels and then blown through the duct into the cooking chamber. In addition, gaseous fluid, which may already contain vapor, is then sucked in through the open side of the heating chamber and blown again through the duct into the cooking chamber by means of the fan wheels, i.e. circulated. In this case, the annular heating element can be activated at least temporarily (ie continuously or in phases) in order to increase a steam temperature of the steam blown into the cooking chamber. This increase can be so strong that superheated steam is generated ("SHS mode"). Alternatively, the ring heating element can be deactivated if required, which also enables steam treatment of the food to be cooked only with wet steam ("wet steam operating mode"). That the cooking appliance is set up to Operating mode to operate the evaporator at least temporarily includes that this possibility is given, but does not need to be used. Thus, in a further development, the evaporator can only be operated initially until a predetermined amount of steam is reached. Individual bursts of steam can also be generated, for example.

It is a further development that the channel is a profile-shaped channel with a constant cross section, ie it does not taper. The flow opening of the channel on the heating space side then corresponds in particular to the flow opening on the cooking space side. Such a channel is particularly easy to produce.

In one configuration, the channel tapers at least in sections in the direction of the cooking chamber. The advantage is thus achieved that a pressure loss of the flow flowing from the heating chamber into the cooking chamber through the duct is noticeably reduced. The taper can, for example, be in the form of a truncated cone or have a curved shape in cross section--for example in the manner of a sector of a circle, oval, parabolic, etc. The flow cross section of the channel on the heating chamber side is then in particular larger than the flow cross section on the cooking chamber side. The fact that the channel tapers at least in sections in the direction of the cooking space can include that the channel tapers over its entire depth in the direction of the cooking space or can include that it has at least one tapering section and at least one non-tapering depth section.

It is a further development that the duct narrows in cross section between the rear flow opening on the heating chamber side and the front flow opening on the cooking chamber side by 10 mm to 100 mm, particularly advantageously by 15 mm to 30 mm.

It is a further development that the channel has a circular ring shape in a front view, but is not limited to this. For example, it can also be oval, angular (e.g. rectangular) or free-form when viewed from the front.

It is a further development that the channel at its rear flow opening has a flow cross-sectional area in the range between approx. 30 cm ² and approx. 700 cm ² , in particular between approx. 60 cm ² and 300 cm ² , with a circular flow opening in particular in particular has a diameter of between approx. 3 cm and approx. 30 cm, in particular between approx. 9 cm and approx. 20 cm.

In one embodiment, the fan wheels dip into the channel with their front sections on the cooking chamber side and are arranged in the heating chamber with their rear sections on the heating chamber side. In this way, the advantage of a compact structure that can be implemented in a particularly simple manner is achieved, in which the cooking chamber is particularly deep. In addition, mass flow and pressure losses can advantageously be further reduced in this way when fluid is blown into the channel.

In one configuration, the channel has a depth of between 2 mm and 50 mm, particularly advantageously between 5 mm and 15 mm.

In a further development, the fan wheels have a depth along the depth extension or their axis of rotation of between 10 mm and 40 cm, particularly advantageously between 15 mm and 30 mm. In this way, the depth of the cooking chamber can advantageously be kept particularly large, or the depth of the heating chamber can be kept particularly small.

In one configuration, the baffle wall has an at least approximately planar shape, except for the channel. This achieves the advantage that the lateral opening of the heating chamber can be designed to be open all around with a large flow cross-section, which enables the fluid to be sucked out of the cooking chamber in a particularly uniform, all-round manner. The fact that the lateral opening is open all the way around can include, in a development, that the lateral edge of the baffle wall does not form any wall sections that impede the flow, e.g. However, it can be widened, e.g. in the direction of the cooking chamber, e.g. bent forward at the edge. In another development, the lateral opening being open all the way around can include the lateral edge being partially or completely embodied as a bent-in wall section which, however, leaves at least a gap up to the muffle or does not contact the muffle.

The fact that the baffle wall has an "at least approximately" flat shape can include the baffle wall having bulges, eg beads, with a small depth, which however have no or only a negligibly small influence on the mass flow of the fluid. Such beads can, for example, increase the stability of the impact wall. also is It is possible for the baffle wall to have one or more flow guide elements such as ribs etc. on its surface on the heating room side, which can support targeted, uniform suction or blowing out of the fluid. Beads can also have a flow guiding function. The fact that the baffle has an “at least approximately” flat shape can also include the baffle having a base body (eg a metal sheet) with an approximately flat shape, to which additional air guiding structures are attached, eg air baffles in the form of ribs or fins. Additionally or alternatively, holes outside the flow opening can be present in the at least approximately planar baffle.

In a further development, the baffle wall is fastened to the rear wall of the muffle by spacers, in particular in the form of pins or bolts.

In one embodiment, the channel is covered by a grid. This achieves the advantage that gaseous fluid can flow through the channel practically unhindered and at the same time the fan wheels are protected, e.g. from food to be cooked positioned deep in the cooking chamber, fingers of a user, etc.

It is a further development that the ring heater surrounds the fan wheels on the side, which enables a compact design with a particularly small depth.

In one embodiment, the annular heating element is arranged closer to the rear wall of the muffle than the fan wheels. This achieves the advantage that the annular heater is positioned in the fluid flow in a particularly reliable manner and over a large area, which enables particularly effective heat transfer to the fluid by means of the annular heater. This is particularly advantageous when the cooking appliance is operated in an SHS operating mode.

In one configuration, the steam inlet is positioned in such a way that steam discharged from it is conducted via the annular heating element, in particular when the axial fan is operated in the first direction of rotation. This allows the advantage that the escaping steam can be heated particularly completely. In a wet-steam operating mode, water droplets can thus be evaporated particularly effectively before the wet-steam is blown into the cooking chamber. In an SHS mode is advantageously achieved that the SHS steam blown into the cooking chamber can be brought to its desired temperature particularly hot and/or with a particularly low heat output.

It is a configuration that the ring heater is equipped with a heat transfer structure. This enables a particularly effective heat transfer to the fluid conducted over it. The heat transfer structure can be, for example, a thermal conduction structure connected to the ring heater—typically designed as a tubular heater—which has a structured surface, for example. For example, the ring heater can be surrounded by a metal mesh or a jacket made of foamed metal.

In a further development, the baffle wall is equipped with at least one air guide structure (e.g. in the form of at least one fin and/or at least one rib) on its side facing the heating chamber, in order to concentrate the fluid sucked laterally into the heating chamber in the first direction of rotation to conduct ring heaters. This also enables a particularly effective heat transfer from the ring heater to the fluid conducted over it.

In one configuration, a fan motor of the axial fan that drives the fan wheels is a speed-controllable motor. As a result, a mass volume flow through the channel can advantageously be adjusted in a targeted manner in order to improve the cooking result.

In one embodiment, there is an additional continuous steam heater between the evaporator and the steam inlet, and thus outside the muffle. In this way, the advantage is achieved that the steam entering the boiler room through the steam inlet can have an increased temperature. This allows, for example, water droplets contained in the wet steam to be evaporated before the wet steam enters the boiler room through the steam inlet. Another benefit is to increase the thermal energy entrained by the steam and then introduced into the cooking cavity.

It is a configuration that the once-through steam heater is provided to increase a temperature of the wet steam discharged from the evaporator by 20°C to 40°C. This is particularly advantageous for reducing water droplets with little energy expenditure. In one configuration, the continuous-flow steam heater is set up to increase a temperature of the wet steam discharged from the evaporator by at least 100° C., in particular up to 500° C., in particular up to 300° C. to 500° C This enables a significant increase in the heat energy carried along by the steam and which can be introduced into the cooking space. In particular, this continuous-flow steam heater is also able to increase the temperature of the wet steam discharged from the evaporator to comparatively lower temperatures, eg by 20° C. to 40° C. in order to reduce the quantity of water droplets carried along.

In one embodiment, the muffle is sealed off in a practically vapor-tight manner when its charging opening is closed by means of a door. This offers the advantage that, after the muffle has been filled with steam for the first time, little or no additional steam needs to be added. This in turn saves energy and water.

In particular, the cooking appliance can be operated in one or more of the following operating modes:

SHS mode of operation in the first direction of rotation: The fan wheels are operated in the first direction of rotation and the evaporator is activated at least in phases. When the evaporator is activated, the wet steam it generates, possibly after additional heating by a continuous-flow steam heater, is introduced through the steam inlet into the boiler room, preferably directed at the activated or energized ring heater. The activated ring heater heats the introduced steam to its target temperature above the boiling point of water, sucks it in as superheated steam from the fan wheels and blows it through the channel in the baffle wall into the cooking chamber. At the same time, gaseous fluid in the cooking chamber (e.g. initially air or vapors, then steam) is sucked into the heating chamber through the side opening, heated by sweeping over the ring heating element and then blown back into the cooking chamber through the channel in the baffle. If present, at least one conventional heating element and/or the microwave generating device can also be activated in the SHS operating mode. SHS operating mode in the second direction of rotation: Compared to the SHS operating mode in the first direction of rotation, the flow through the flow opening and the heating chamber is reversed, whereby dry steam is then blown into the cooking chamber over a large area.

Wet steam operating mode in the first direction of rotation: The wet steam operating mode differs in a further development from the SHS operating mode in that the ring heating element is not or only slightly energized, so that wet steam is blown through the duct into the cooking chamber, resulting in particularly concentrated wet steam -current yields.

Wet steam operating mode in the second direction of rotation: In contrast to the wet steam operating mode in the first direction of rotation, the fan wheels are operated in the second direction of rotation, so that wet steam is blown into the cooking chamber over a large area.

Steam-free operating mode in the second direction of rotation: This includes already known operating modes of an oven and/or microwave oven in which the evaporator is not operated and therefore no steam is introduced into the boiler room through the steam inlet. In particular, a non-steam operating mode can include a conventional circulating air or hot air mode. In order to achieve the most uniform possible heating of the cooking chamber, the fan wheels can be operated in the second direction of rotation, which is the reverse of the first direction of rotation. In this case, gaseous fluid is sucked out of the cooking chamber through the duct and blown back into the cooking chamber over a large area through the side opening of the heating chamber, with the ring heating element activated after previous heating.

Steamless operating mode in the first direction of rotation: In contrast to the steamless operating mode in the second direction of rotation, the fan wheels are now operated in the first direction of rotation, so that hot air is blown through the duct into the cooking chamber, resulting in a particularly concentrated stream of hot air.

In principle, all cooking modes can be provided in the first direction of rotation (then with a concentrated flow) and in the second direction of rotation (then with a more uniform flow over a large area). The object is also achieved by a method for operating a cooking appliance, in particular a household cooking appliance, having a muffle with a loading opening at the front, an impact wall arranged at a distance in front of a rear wall of the muffle, which delimits a rear side of a cooking chamber and, with the rear wall of the muffle, a lateral forms an open heating chamber, an axial fan, the fan wheels of which are arranged in the heating chamber, a ring heater, which is arranged in the heating chamber, a flow opening formed in the baffle wall in the form of a channel that protrudes on the cooking chamber side and does not widen in the direction of the cooking chamber, which carries the fan wheels laterally surrounds at least in sections, and an evaporator arranged outside the muffle, the steam side of which is fluidly connected to a steam inlet opening into the heating chamber, wherein in a steam treatment operating mode, in particular SHS operating mode, the fan wheels are rotated in a first direction of rotation, so that fluid runs out is sucked into the cooking chamber through the side opening of the heating chamber, flows over the activated ring heating element and is then blown back into the cooking chamber through the flow opening and the evaporator is operated at least temporarily.

The method can be designed analogously to the cooking appliance and has the same advantages.

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 a sectional plan view of a sketch of a domestic cooking appliance according to the invention, not to scale; and

2 shows a section of the domestic cooking appliance with fluid flows in SHS operation as a sectional top view. 1 shows a domestic cooking appliance 1 in the form of an oven as a sectional view through its muffle 2 in plan view. 2 shows a section of the domestic cooking appliance 1 with fluid flows in SHS operation as a sectional top view.

The muffle 2 has a loading opening 3 on the front, which can be closed in a vapor-tight manner by a door 4, so that the muffle 2 is practically sealed in a vapor-tight manner when the door 4 is closed.

In the front view of the loading opening 3, a practically flat baffle 6 is arranged in the muffle 2 at a distance in front of a rear wall 5 of the muffle 2. The household cooking appliance 1 has an axial fan 9 whose fan wheels 10 are arranged at least in sections in the heating chamber 8 . The fan wheels 10 can be rotated via a shaft 11 by a bidirectional, in particular speed-controllable fan motor 12 .

A single- or multi-circuit ring heater 13 is arranged in the heating chamber 8 between the fan wheels 10 and the rear wall 5 . This can be equipped with a heat transfer structure 24 .

Here, for example, in the center of baffle 6 is a flow opening in the form of a channel 14 that protrudes on the cooking chamber side and does not widen in the direction of the cooking chamber and that surrounds fan wheels 10 laterally at least in sections. The edges 15 of the channel 14, which is circular here, taper in depth T from back to front or in the direction of the cooking chamber 7, so that a flow opening 16 of the channel 14 on the heating chamber side is larger than its flow opening 17 on the cooking chamber side. The channel 14 can, in particular, in the area of the Flow opening 17 on the cooking chamber side may be covered by a grid 23 .

As shown in more detail in FIG. 2, the fan wheels 10 dip into the channel 14 with their cooking chamber-side sections, which are at the front with respect to a depth T, and are arranged with their heating-chamber-side, rear sections in the heating chamber 8 . The household cooking appliance 1 also has an evaporator 18 which is arranged outside the muffle 2 and whose steam side is fluidically connected to a steam inlet 19 which opens into the heating chamber 8 . The steam inlet 19 is designed and arranged in such a way that steam D discharged therefrom is conducted via the annular heating element 13 .

A continuous steam heater 20 can optionally be present between the steam outlet of the evaporator 18 and the steam inlet 19 . This is set up to increase a temperature of the wet steam discharged from the evaporator 18 by at least 20° C. to 40° C., advantageously even by at least 100° C.

Also indicated is a bottom heating element 21, which can be designed, for example, as a tubular resistance heating element.

The fan motor 12, the tubular heating element 13, the evaporator 18, the continuous-flow steam heater 20, the bottom heating element 21, etc. can be controlled by means of a control device 22, e.g.

In the SHS operating mode now described, without taking into account the continuous-flow steam heater 20, steam D in the form of wet steam is routed to the activated annular heating element 13, which heats the wet steam to such an extent that superheated steam SHS is produced, e.g. with a temperature of up to approx. 600ºC. At the same time, the fan wheels 10 are driven in a first direction of rotation R1 by the fan motor 12 in such a way that the superheated steam SHS that has just been generated and is in the heating chamber 8 is sucked in and blown through the duct 14 into the cooking chamber 7 . In addition, gaseous fluid G is also sucked out of the cooking chamber 7 through the lateral opening 25 of the heating chamber 7, flows over the activated annular heating element 13 and is then blown back through the channel 14 into the cooking chamber 7 together with the superheated steam SHS that has just been generated. In the process, the gaseous fluid G sucked in from the cooking chamber 7 is also heated, so that it is also converted into superheated steam SHS or, if it is already present as superheated steam SHS, is kept at its target temperature. In the heating chamber 8, the gaseous fluid G sucked in from the cooking chamber 7 is thus mixed with the superheated steam SHS just generated. The bottom heating element 21 and possibly other heating elements (not shown) can be activated or not.

In one variant, the evaporator 18 is only operated in phases, e.g. only initially until a predetermined degree of humidity is reached in the cooking chamber 7. Outside of a vapor phase, only the fluid G is circulated and is kept at its target temperature by the ring heater 13 by compensating for heat losses.

In at least one other operating mode, e.g. in a conventional hot-air operating mode, the fan wheels 10 can be operated by reversing the movement of the fan motor 12 in a second direction of rotation opposite to the first direction of rotation R1, with or without the supply of steam D. The gaseous Fluid G is drawn in through the channel 14 and, possibly mixed with steam D newly supplied through the steam inlet 19, blown out through the side opening 25 of the heating chamber 7, which enables a particularly uniform temperature and humidity distribution in the cooking chamber 7.

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 household cooking appliance

2 muffles

3 loading opening

4 door

5 back wall of the muffle

6 baffle

7 cooking space

8 boiler room

9 axial fans

10 fan wheel

11 wave

12 fan motor

13 ring heaters

14 channel

15 edges of the canal

16 Flow opening on the boiler room side

17 Flow opening on the cooking chamber side

18 evaporators

19 steam inlet

20 continuous flow steam heater

21 bottom heat radiator

22 controller

23 grids

24 heat transfer structure

25 Lateral opening of the boiler room

D steam

G Gaseous fluid

R1 First direction of rotation

SHS Superheated Steam T Depth Extension

Claims

PATENT CLAIMS 1. Cooking appliance (1), in particular a household cooking appliance - a muffle (2) with a front loading opening (3), - an impact wall (6) arranged at a distance in front of a rear wall (5) of the muffle (2), which delimits a rear side of a cooking chamber (7) and forms a laterally open heating chamber (8) with the rear wall (5) of the muffle (2), - an axial fan (9), the fan wheels (10) of which are at least partially arranged in the heating chamber (8), - a ring heater (13) which is arranged in the heating space (8), - A flow opening formed in the baffle (6) in the form of a channel (14) which protrudes on the cooking chamber side and does not widen in the direction of the cooking chamber (7) and which surrounds the fan wheels (10) laterally at least in sections, and - an evaporator (18) arranged outside the muffle (2), the steam side of which is fluidly connected to a steam inlet (10) opening into the heating chamber (8), the cooking appliance (1) - Is set up in at least one steam treatment mode, in particular SHS mode, to operate the fan wheels (10) in a first direction of rotation (R1) so that gaseous fluid (G) from the cooking chamber (7) through the lateral opening ( 25) of the heating chamber (8), flows over the activated annular heating element (13) and is then blown back into the cooking chamber (7) through the duct (14), and is set up to operate the evaporator (18) at least temporarily , - Is set up in at least one other operating mode to operate the fan wheels (10) under a first direction of rotation (R1) opposite to the second direction of rotation. 2. Cooking appliance (1) according to claim 1, wherein the channel (14) tapers in the direction of the cooking chamber (7). 3. Cooking appliance (1) according to one of the preceding claims, wherein the fan wheels (10) are arranged with their front sections on the cooking chamber side in the channel (14) and with their rear sections on the heating chamber side in the heating chamber (8). 4. Cooking appliance (1) according to one of the preceding claims, wherein the channel (14) has a depth of between 2 mm and 50 mm, in particular between 5 mm and 15 mm. 5. Cooking appliance (1) according to any one of the preceding claims, wherein the baffle (6) up to the channel (14) has an at least approximately flat shape. 6. Cooking appliance (1) according to any one of the preceding claims, wherein the channel (14) is covered by a grid (23). 7. Cooking appliance (1) according to any one of the preceding claims, wherein the ring heater (13) is arranged closer to the rear wall of the muffle (2) than the fan wheels (10). 8. Cooking appliance (1) according to one of the preceding claims, wherein the steam inlet (10) is positioned in such a way that steam (D) released therefrom, in particular when the fan wheels (10) rotate in the first direction of rotation (R1), via the annular heating element (13) is directed. 9. Cooking appliance (1) according to one of the preceding claims, wherein the annular heating element (13) is equipped with a heat transfer structure (24) and/or the side of the baffle wall (6) facing the heating chamber (8) is equipped with at least one air guide structure, which is designed to direct a flow of the fluid (G) over the activated ring heater (13). 10. Cooking appliance (1) according to one of the preceding claims, wherein the fan wheels (10) driving the motor (12) of the axial fan (9) is a speed controllable motor. 11. Cooking appliance (1) according to any one of the preceding claims, wherein between the evaporator (18) and the steam inlet (10) an additional flow steam heater (20) is present. 12. The cooking appliance (1) according to claim 11, wherein the continuous-flow steam heater (20) is set up to increase a temperature of the wet steam discharged from the evaporator (18) by 20° C. to 40° C. 13. Cooking appliance (1) according to one of claims 11 to 12, wherein the continuous steam heater (20) is set up to increase a temperature of the evaporator (18) discharged wet steam by at least 100 °C. 14. Cooking appliance (1) according to any one of the preceding claims, wherein the muffle (2) when its loading opening (3) is closed by means of a door (4), is sealed practically steam-tight. 15. A method for operating a cooking appliance (1), in particular a household cooking appliance - a muffle (2) with a front loading opening (3), - an impact wall (6) arranged at a distance in front of a rear wall (5) of the muffle (2), which delimits a rear side of a cooking chamber (7) and forms a laterally open heating chamber (8) with the rear wall (5) of the muffle (2), - an axial fan (9) whose fan wheels (10) are arranged in the heating chamber (8), - a ring heater (13) which is arranged in the heating space (8), - A flow opening formed in the baffle (6) in the form of a channel (14) which protrudes on the cooking chamber side and does not widen in the direction of the cooking chamber (7) and which surrounds the fan wheels (10) laterally at least in sections, and - an evaporator (18) arranged outside the muffle (2), the steam side of which is fluidly connected to a steam inlet (10) opening into the heating chamber (8), wherein in a steam treatment operating mode, in particular SHS operating mode, 22 - the fan wheels (10) are rotated in a first direction of rotation (R1), so that fluid (G) is sucked out of the cooking chamber (7) through the lateral opening (25) of the heating chamber (8) via the activated annular heating element (13) flows and is then blown through the channel (14) back into the cooking chamber (7) and - the evaporator (18) is operated at least temporarily.