EP4639029A1

EP4639029A1 - Hydrogen combustion burner assembly for a gas cooking assembly, gas cooking appliance having a hydrogen combustion burner assembly, and method of manufacturing a hydrogen combustion burner assembly

Info

Publication number: EP4639029A1
Application number: EP23829076.1A
Authority: EP
Inventors: Fabio SPANÓ; Nicola Guardigli; Ferdinando VIVACQUA; Areli URIBE PORTUGAL; Fabio Rasi
Original assignee: Electrolux Appliances AB
Current assignee: Electrolux Appliances AB
Priority date: 2022-12-20
Filing date: 2023-12-18
Publication date: 2025-10-29
Also published as: WO2024133136A1; EP4390222A1; AU2023413527A1; CN120283129A

Abstract

The underlying invention is, in particular, directed to a hydrogen combustion burner assembly (3) for a gas cooking appliance (1) and configured for the combustion of pure hydrogen. The hydrogen combustion burner assembly (3) comprises a burner body (7) with an inner volume for supplying hydrogen gas from a gas inlet opening (10) to a plurality of gas outlet openings (13); a cup-shaped recess (28) open at the second side (S2) and defined by a circumferential collar (15) having a distal face side oriented away from the burner body (7), and comprising a plurality of groove-like depressions (27) in the distal face side; a passageway (11) fluidly connecting the gas inlet opening (10) to the cup-shaped recess (28); and a substantially flat cover plate (16) placed on, wherein the burner body (7) is a one-piece part having a continuous inner wall structure that seals the inner volume, except for the gas inlet opening (10) and outlet openings (13), against the outer atmosphere (14) in an airtight manner.

Description

HYDROGEN COMBUSTION BURNER ASSEMBLY FOR A GAS COOKING ASSEMBLY, GAS

COOKING APPLIANCE HAVING A HYDROGEN COMBUSTION BURNER ASSEMBLY, AND

METHOD OF MANUFACTURING A HYDROGEN COMBUSTION BURNER ASSEMBLY

The present invention relates to a hydrogen combustion burner assembly for a gas cooking appliance, in particular a gas cooking hob or gas range, more particularly a gas cooking hob, comprising a hydrogen combustion burner assembly and configured to heat cooking vessels by means of the combustion of pure hydrogen or substantially pure hydrogen.

The present invention also relates to a gas cooking appliance, preferentially a gas cooking hob or gas range, comprising at least one hydrogen combustion burner assembly and configured for heating cooking vessels by means of the combustion of pure hydrogen or substantially pure hydrogen.

The present invention further relates to a method of manufacturing a hydrogen gas combustion burner assembly.

Gas cooking hobs for the thermal treatment of food products are commonly known. Typically gas cooking hobs or gas ranges comprise one or more heating zones, each comprising a gas combustion burner assembly, which allows the controlled burning of the gas such as e.g. natural gas, liquefied petroleum gas, town gas or the like, or generally carbon-based gases or gas mixtures .

Besides gas cooking hobs suitable for burning carbon-based gases, such as hydrocarbon gases (e.g. methane, propane, butane) , e.g. described in US 8,753,112 B2, cooking hobs suitable for being fed with Oxyhydrogen, i.e. a mixture of oxygen and hydrogen, have been developed, e.g. as described in EP 2 146 144 A2. Combustion burner assemblies for conventional carbon-based gases are comparatively complex, requiring several different and separate parts , such as a base body and a crown to be assembled such that in the assembled state a suitable passageway for supplying primary air is established . Even though the known gas cooking hobs work satisf yingly, an interest is seen in the sector to further reduce the ecological impact of the preparation of food products .

Gas burner assemblies suitable for being fed with Oxyhydrogen ( HHO ) are comparatively critical with regard to safety, operation and handling due the comparatively high explosiveness of Oxyhydrogen - being a mixture of oxygen and hydrogen, supplied and fed in substantially stoichiometric ratio . This is of particular relevance , because gas burner assemblies for cooking are usually installed and used in locations , such as at the user' s home or kitchen, with the typical user not trained for handling HHO , which is significantly more explosive as compared to carbon-based gases . Due to the comparatively high explosiveness , the manufacturing process for such burners is comparatively complex , requiring all parts of the gas supply and routing to be firmly attached to each other to avoid parts of the burner be thrown off in case of a blast caused by malfunction or operating errors .

In view of this , an alternative combustion burner for the heating of cooking vessels shall be provided that is comparatively easy to manufacture , provides comparatively safe operation with regard to explosiveness of the gaseous fuel used, and is apt to reduce the ecological impact .

This obj ective is solved by the present invention, which is respectively defined by the features of the independent claims . Embodiments result from the dependent claims and the exemplary embodiments described below and in connection with the annexed figures . According to an embodiment according to the underlying invention, a hydrogen combustion burner assembly for a gas cooking appliance is provided, and which is configured for, i.e. it is specially adapted to, the combustion of pure or substantially pure hydrogen, i.e. gaseous hydrogen. The hydrogen combustion burner may be provided for household or industrial use for cooking purposes.

The expression pure or substantially pure hydrogen shall mean that the burner assembly as such is configured for burning pure hydrogen or hydrogen gas consisting of hydrogen (H2) and possible traces, contaminants and/or admixed substances other than hydrogen (H2) of negligible amount, but no oxygen gas (02) . Accordingly, the term "substantially pure hydrogen gas" shall relate to gaseous hydrogen (H2) that is void of oxygen (02) , and may include substances other than hydrogen (H2) . Substantially pure hydrogen gas shall also cover mixtures with negligible traces or admixtures, i.e. negligible in terms of combustion and heating, of other gaseous fuels or components, but no oxygen (02) . For the avoidance of doubt, pure or substantially pure hydrogen gas shall related to gaseous hydrogen fuel in which hydrogen (H2) is the main fuel component, but does not include and is void of oxygen (02) . It is to be noted that the suggested gas burner assembly is specifically adapted to, designed and suitable for use with pure hydrogen gas directly supplied to the hydrogen gas burner assembly, i.e. to a burner body thereof, from a gas supply line associated with a local hydrogen gas tank, hydrogen gas container, or a public hydrogen gas grid based on H2 gas .

The hydrogen combustion burner assembly comprises a burner body with an inner volume or inner free volume, i.e. a burner body with a wall structure that defines an inner volume. The inner volume is for supplying hydrogen gas or gaseous hydrogen from a gas inlet opening of the burner body to a plurality of gas outlet openings. In terms of ordinary operation, the gas outlet openings can be termed flame ports because , when ignited, gas exiting the gas outlet openings is burnt off , for example to heat a cooking vessel placed over the gas burner assembly . The gas inlet opening represents a supply opening for feeding hydrogen gas from a source , such as a gas bottle , container or a public or private hydrogen gas grid . The gas inlet opening may be associated with or be part of a gas inlet interface for connection to a hydrogen gas supply line , for example . The burner body is designed such that the hydrogen gas ( H2 ) is free of oxygen (02 ) while it is inside the burner body, which has no air inlets that could allow oxygen entering the burner body during use and admix with the hydrogen inside the burner body . In terms of conventional gas burners , the burner body does not have so-called primary air inlets . For the combustion of the hydrogen at the burner body, the hydrogen mixes with ambient air and forms a combustible mixture with the atmospheric oxygen, i . e . the oxygen in the ambient air , only when it exits the flame ports . Then it can be ignited .

The gas inlet opening is located at a first side of the burner body, wherein in the ordinary arrangement and orientation of use and operation, the first side may be considered a lower side of the burner body . The outlet openings are located at a second side of the burner body, opposite the first side . Considering ordinary use , installation, and operation, this second side may be termed an upper side , i . e . the side facing a bottom of a cooking vessel placed over the burner assembly for heating the vessel .

The burner body comprises a cup-shaped recess that is open at the second side , i . e . it opens upwards , and is defined by a bottom wall and a circumferential collar or circumferential wall , proj ecting at the second side .

The circumferential collar , briefly referred to herein also as collar, has a distal face side oriented away from the burner body at the second side . The distal face side corresponds to the face side of the collar when viewed in a top view from the second side . The term distal shall mean that the face side represents the outermost side of the burner body with regard the direction from the first side to the second side . For the purpose of reference , an axis running parallel to the direction from the first side to the second side of the burner body is referred to herein as longitudinal axis , which may be a center axis . The distal face side preferably defines a plane that is substantially parallel , preferably truly parallel to a plane that is perpendicular to the longitudinal axis .

The collar comprises a plurality of groove-like depressions or recesses in free the distal face side . The depressions traverse the circumferential collar, i . e . they extend from an inner side of the collar facing the cup-shaped recess to an outer side of the burner body . Preferably, the depressions respectively extend or run locally perpendicular to the collar, e . g . parallel to a local normal vector of a wall of the collar at the respective depression . Or , in other words , the depressions cross the collar, preferably locally perpendicular to the collar . This in particular means that the depressions crossing the collar have minimal length measured transversely to the collar . The angular orientation and thus length of the depressions may be relevant with regard to obtaining a desired or advantageous flame pattern, as , for example , the length of the depressions , which form the flame ports in the assembled state together with their diameter may affect the pressure distribution . In particular, the depressions extend from an inner side of the collar facing the cup-shaped recess to an outer side of the collar averted from the inner side , e . g . an outer side facing the outer atmosphere of the burner body . A bottom or base area of the depressions may be parallel to a plane that is perpendicular to the longitudinal axis , i . e . the bottom or base area may be perpendicular to the longitudinal axis . However , it is possible , that the bottom or base are of one or more of the depressions is inclined relative to a plane that is perpendicular to the longitudinal axis .

The burner body further comprises a passageway, in particular an inner passageway or pass-through, fluidly connecting the gas inlet opening to the cup-shaped recess . That is , the passageway interconnects the inlet opening to the cup-shaped recess for supplying hydrogen gas that is supplied via the inlet opening from a gas line to the cup-shaped recess . In the operational and assembled state , hydrogen gas supplied to the cup-shaped recess finally exits the flame ports and can be ignited at an outer side or the burner body and burnt for heating a vessel . Again, for the combustion of the hydrogen at the burner body, more precisely at the flame ports , the hydrogen mixes with ambient air and forms a combustible mixture with the atmospheric oxygen only when it exits the flame ports . Then it can be ignited .

The combustion burner assembly further comprises a substantially flat cover plate ( referred to herein also as cover ) placed on or adapted for placement on the distal face side to cover the cup-shaped recess and the depressions at and from the second side when placed on the burner body . In the ordinary operational assembled state with the cover placed on the burner body, the cover closes the cup-shaped recess and the depressions at and from the second side , and thus establishes a gas distribution camber, in particular for the formation of a hydrogen gas atmosphere therein if fed with hydrogen via the passageway . The gas distribution chamber is defined by the volume of the cup-shaped recess as covered by the cover . Further , the cover placed on the distal face side of the collar, defines a plurality of outlet openings respectively defined by the volume of a depression as covered by the cover . The outlet openings define flame ports as mentioned above . The cover being flat in particular shall mean, for example , that upper and lower sides of the cover, i . e . sides facing away from the burner body and facing towards the burner body, respectively, in the assembled state , may be approximated by two or more substantially parallel planes . If , for example , the cup-shaped recess and/or the circumferential collar have/has a circular shape , the cover may be formed as a flat circular plate , e . g . like a disc . The shape of the cup-shaped recess and/or circumferential collar, however, is not limited to circular , but may have other shapes such as elliptical , ovoid, or a shape like a Cassini curve . The collar may accordingly have a corresponding elliptical , ovoid of Cassini-curve like shape . The term flat shall , however, not exclude the cover, in particular a side of the cover , such as a side facing the cup-shaped recess when put on the burner body, having a stepped surface structure . For example , the cover may comprise , e . g . on the lower side or the side facing the burner body, two or more sections or areas at different height levels (with regard to the center normal ) of the cover .

As an example , the lower side of the cover may include an outer annular surface area adj acent to an inner circular surface area, with the outer annular surface are being set back relative to the inner circular surface area . The outer annular surface are may be provided for covering the depressions when placed on the collar , whilst a step or shoulder in the transitional area to the inner circular surface are may be provided for abutting or interacting with centering elements implemented on or at the burner body, e . g . on an inner side of the collar . The centering elements may for example be provided as protrusions proj ecting inwardly from the inner side of the collar . This may be advantageous and support proper alignment of the cover on the burner body .

As outlined above , when the base body is covered by the cover plate , the depressions define the gas outlet openings , and the cup-shaped recess defines a gas supply chamber, wherein the gas supply chamber is in fluidic communication with the gas inlet opening, via the passageway, on the one hand, and with the outlet openings on the other hand for supplying gas from the gas inlet opening to the gas outlet openings via the gas supply chamber . Further , the gas outlet openings are , on the one hand in fluidic communication with the gas supply chamber , and, on the other hand, with the outer atmosphere .

With the suggested hydrogen combustion burner assembly, the distal face side comprises , respectively between adj acent depressions in circumferential direction of the collar , substantially flat ( or : smooth) bearing surfaces that rest against the cover plate in the assembled state , i . e . when the cover is placed or installed on the burner body, and that at least suppress hydrogen gas cross-talk between the depressions in circumferential direction of the collar and/or transversely to the collar . Further , the flat surfaces inhibit or at least suitably suppress cross-talk of atmospheric air, in particular atmospheric oxygen (02 ) with hydrogen across the circumferential wall . In particular, the surfaces of the distal face side of the collar and of the cover that rest against each other in the assembled state are suitably flat or smooth such that cross-talk between neighboring depressions and/or hydrogen and atmospheric oxygen is inhibited or precluded during ordinary operation . Here , the fact that the cover and bearing surfaces , at least corresponding abutment areas , are flat and appropriately smooth is one aspect to obtain adequate tightness for avoiding gas cross-talk during operation .

The term gas cross-talk shall mean the event of gaseous hydrogen entering one outlet opening and propagating to a neighboring outlet opening by passing between the bearing surface and the cover , and/or the event of gaseous hydrogen exiting from the gas supply chamber to the outer atmosphere by passing between the bearing surface and the cover , and/or oxygen entering from the outer atmosphere between the bearing surfaces . Avoiding such cross-talk, which is accomplished by providing the flat ( or : smooth ) surfaces at the bearing surfaces and cover, respectively, and resting against each other, has been found to improve the resulting flame pattern, in particular in view of the fact that hydrogen, due to its reduced molecular size , is much more penetrating that conventional carbon-based gases . In particular, and despite the comparatively low molecular weight and size , and higher penetrability, the invention is based on the finding that appropriate operation may be obtained by using corresponding flat surfaces , without necessarily requiring means for urging the cover onto the bearing surfaces . However , providing such means , e . g . screw fastening , may be applied in embodiments .

In accordance with the suggested hydrogen combustion burner assembly, the burner body is a one-piece part having a continuous inner wall structure that seals , in the assembled state , the inner volume , except for the gas inlet opening and outlet openings , against the outer atmosphere in an airtight manner . In other words , the walls of the burner body, adj acent to and defining the cup-shaped recess , and the passageway are airtight and are void of any openings , pass-troughs , or gaps between the inner volume and the outer atmosphere . This means , that in the assembled state , when the cover is placed on the burner body, the inlet opening and the outlet openings represent the only fluidic passageways for gaseous hydrogen to and from the burner body . As compared to conventional carbon-based burners , the burner body as suggested is void of so-called "primary air" supply ducts or passageways for supplying primary air from the outer atmosphere to the inner volume before the gas exits the flame ports .

Implementing the burner body in the airtight manner has been found to be important for avoiding oxygen contained in ambient air to mix with hydrogen gas within the inner volume of the burner body before exiting the outlet openings . In particular, by avoiding entrance of oxygen in the way described, appropriate flame patters for pure hydrogen gas combustion can be obtained . Further , the risk of gas mixtures with increased explosive properties , which would be the case if the hydrogen gas was enriched with oxygen before exiting the outlet openings , can be avoided .

In all , the above discussion reveals , that the suggested hydrogen combustion burner solves the underlying problem. In particular it is possible to reduce the carbon footprint as compared to conventional burners . Further, the combustion burner assembly is of simple construction, may be easily manufactured, and enables safety-compliant operation and combustion of pure hydrogen gas for use in cooking even for untrained users , for example for household and also industrial cooking purposes . The burner body does not require primary air ducts as required with conventional burners , but may be efficiently operated with secondary air only, i . e . ambient air provided from the outer atmosphere of the burner body at the flame holes .

In embodiments , the passageway interconnects , i . e . fluidly interconnects , the gas inlet opening and the cup-shaped recess . For example , at the bottom of the cup-shaped recess , there may be an aperture represented by an orifice of the passageway leading into the cup-shaped recess . The interconnection may be void of any breakthroughs or recesses passing or extending from the passageway to the outer atmosphere through burner body . Considering the volume of the passageway leading from the gas inlet opening to the cup-shaped recess , in particular a bottom part of the cup-shaped recess , this volume does , in absence of breakthroughs etc . and except for the gas inlet opening and an the orifice leading into the cup-shaped recess , not include any further openings . Accordingly, the burner body is void of any primary air supply channels or the like . Hydrogen is burnt at the exit of the flame ports using merely secondary air drawn from the outer atmosphere .

The passageway preferably includes a noz zle in particular inj ection noz zle , or a seat for attaching a nozzle . A corresponding nozzle may be adapted to control passage of hydrogen gas from the inlet opening to the gas supply chamber, i.e. control injection of hydrogen gas into the gas supply chamber. The nozzle may be configured and provided as a pressure regulating means in that the input pressure prevailing at the inlet opening is reduced to an operational pressure prevailing in the gas supply chamber during operation. As an example, the input pressure may be in the region of 20 mbar, corresponding to conventional gas pressures of gas supply lines or grids, and the nozzle may regulate this pressure to operational pressure values in the range from 0.2 mbar to 3 mbar or more, depending on maximal burner power and burner design, e.g. on size and/or number of the outlet openings and/or length of the outlet opening.

As an example, with a 1 kW (Kilowatt) maximal power burner the operational pressure (at maximal power) may be at about 0.2 mbar for a burner assembly having 8 outlet openings with a cross-sectional size of 1 mm x 1 mm. In another example, the operational pressure may be at or at least 1.1 mbar for a burner assembly having 12 outlet openings with a size of 0.5 mm x 0.5 mm and maximal burner power IkW. For a 2 kW maximal power burner, the operational pressure (at maximal burner power) may be at about 0.4 mbar for a burner assembly having 12 outlet openings with a cross-sectional size of 1 mm x 1 mm; or the operational pressure may be at or at least 2.3 mbar for a burner assembly having 16 outlet openings with a cross-sectional size of 0.5 mm x 0.5 mm. For a burner having a maximal burner power of 3.5 kW or more, the operational pressure (at maximal burner power) may be at about 0.55 mbar for a burner assembly having 16 outlet openings with a cross-sectional size of 1 mm x 1 mm; or the operational pressure may be at or at least 3 mbar for a burner assembly having 28 outlet openings with a cross-sectional size of 0.5 mm x 0.5 mm. The mentioned examples represent particular embodiments that have been elaborated in connection with conceiving the underlying invention through intensive investigation, modeling, calculation and experimentation. It is to be noted that the mentioned pressures and dimensions and respective ranges given further below, are not j ust arbitrary selections , but are based on substantial investigation in terms of developing a hydrogen combustion burner suitable for burning pure hydrogen and providing appropriate burner and flame characteristics . This aspect apples to all other ranges , sizes and dimensions mentioned elsewhere hereinbelow . In particular, the mentioned ranges , sizes and dimensions provide for the hydrogen combustion burner as suggested good cross lighting capabilities , i . e . spread of an ignition spark over the flame ports along the outer circumference of the burner body in response to an ignition event , good combustion capabilities and flame characteristics .

Preferably, the noz zle made from brass .

In embodiments , the cover is preferably a disc or is disc-shaped, having at least one flat surface , in particular at least one flat surface section that , in the assembled state , bears against the bearing surfaces of the distal face side . In particular, the cover may be a flat-shaped disc, such as a circular, oval , or ovoid plate .

The bearing surfaces and the flat ( or : smooth) surface of the cover bearing against other in the assembled state may preferably have a flatness ( or : smoothness ) lower than 0 . 3 mm .

In this regard, the flatness may be determined as the distance between two fictitious parallel planes running parallel to a corresponding side or surface the cover or perpendicular to the surface normal of the cover, in which one plane passes through the lowest surface point of that surface or surface section and one plane passes through the highest surface point of that surface or surface section, wherein the terms "highest" and "lowest" relate to the level measured parallel to the surface normal or perpendicular to the surface or surface are . Using such flatness , i . e . lower than 0 . 3 mm has been shown suitable for suppressing , or completely or substantially eliminating gas cross-talk, even without intermediate gadgets or similar , and/or even without the need for attaching or urging the cover and collar against each other . Cross-talk has been found to deteriorate combustion and flame shape , wherein, as has been found, cross-talk, in particular cross-talk between adj acent output openings in circumferential direction of the collar and transversely to the collar between the abutment surfaces of the distal face side , on the one hand, and of the cover , on the other hand, represents one , in particular material , aspect in view of the low molecular weight of hydrogen gas compared to conventional gas fuels , such as carbon-based fuels and even Oxyhydrogen .

In embodiments , and as indicated further above , the cover and/or the burner body may include one or more centering elements such as proj ections and/or shoulders arranged and configured for mechanical interaction to properly align the cover and the burner body in the assembled state .

In embodiments , all of the depressions or one or more groups of depressions may have substantially equal geometric dimensions or shape , in particular substantially the same size , cross section, and length transversely to the circumferential collar . With regard to varying dimensions , there may for example be two groups of depressions , each group having depressions of same ( i . e . substantially same ) geometric dimensions . Depressions of such groups may be arranged in circumferential in an alternating arrangement , e . g . the depressions may be provided and distributed in a nested arrangement over the circumference of the collar . In a preferred embodiment , all depressions have the same geometry and size .

In embodiments , the depressions may have a rectangular, preferably square , cross section in planes perpendicular to the longitudinal axis of the depressions transversely to the circumferential collar. The bottom of respective rectangular depressions may be substantially flat, and may run substantially parallel to the distal face side. The bottom of the depressions may have a rectangular shape. In embodiments, the longitudinal cross section of the depression may substantially constant along the longitudinal axis of the depressions.

In embodiments, a size of the depressions measured in planes perpendicular to the longitudinal axis of respective depression may be in the range given by 0.4 mm x 0.4 mm to 1.4 mm x 1.4 mm, preferably 0.5 mm x 0.5 mm to 1 mm x 1 mm. Such ranges, in particular in combination with other burner parameters, such as operating pressure (at maximal burner power) , maximal burner power, total number of flame ports etc. have been shown to provide good combustion and advantageous cross lighting properties .

In embodiments, in the assembled state, the cover may be loosely placed on the burner body. Preferably, in such embodiments, the size of the depressions measured in planes perpendicular to the longitudinal axis of respective depression may be in the range given by 0.8 mm x 0.8 mm to 1.2 mm x 1.2 mm, in particular 1 mm x 1 mm. Depending on maximal burner power, such embodiments may involve operating pressures in the range between 0.2 mbar and 0.6 mbar for burner powers between 1 kW and 3.5 kW (or >3.5 kW) , for example 0.2 mbar for 1 kW, 0.4 mbar for 2 kW, and 0.55 mbar for 3.5 kW (or >3.5 kW) .

In embodiments, the cover may be removably attached, in particular screwmounted, to the burner body. In this case, in the assembled state, the cover is fixed, i.e. attached, to the burner body. Such embodiments may involve smaller outlet opening or depression cross sections and higher operational pressures as compared to embodiments in which the cover is loosely placed on the burner body. Preferably, in such embodiments including attached cover, the size of the depressions measured in planes perpendicular to the longitudinal axis of respective depression may be in the range given by 0.4 mm x 0.4 mm to 0.5 mm x 0.6 mm, in particular 0.5 mm x 0.5 mm. Depending on maximal burner power, such embodiments may involve operating pressures in the range given by 1 mbar and 3 mbar or more for burner powers between 1 kW and 3.5 kW (or more) , for example 1.1 mbar (or higher) for 1 kW, 2.3 mbar (or higher) for 2 kW, and 3 mbar (or higher) for 3.5 kW (or >3.5 kW) .

In embodiments, in the assembled state, the cover may laterally project beyond an outer rim of the circumferential collar. In other embodiments, the cover may be dimensioned such that, in the assembled state, i.e. when the cover is properly placed on the burner body, the cover is substantially flush with the outer rim of the circumferential collar.

In embodiments, the hydrogen combustion burner assembly may be associated with a specified maximal burner power and the nozzle may be configured to regulate the internal pressure (at maximal burner poser) in the gas supply chamber. For example, the nozzle may be adapted such that a ratio between the internal pressure in the gas supply chamber measured in millibar (mbar) and the maximal burner power measured in Kilowatt (kW) is in the range from 0.1 mbar/kW to 1 mbar/kW, preferably from 0.2 mbar/kW to 0.9 mbar/kW. For example a burner assembly with the cover loosely placed on the burner body may involve about or around 0.2 mbar at 1 kW (ratio 0.2 mbar/kW) , about or around 0.4 mbar at 2 kW (ratio 0.2 mbar/kW) , and about or around 0.55 mbar at 3.5 kW (ratio about 0.157 mbar/kW) . Embodiments having the cover attached to the burner body, may involve at least or around 1.1 mbar at 1 kW (ratio 1.1 mbar/kW) , about or around 2.3 mbar at 2 kW (ratio 1.15 mbar/kW) , and about or around 3 mbar at 3.5 kW (ratio about 0.875 mbar/kW) . The given ratios have been proven to provide good combustion and/or cross-lighting.

A corresponding inlet pressure at the inlet opening may be 20 mbar, for example . In embodiments , the hydrogen combustion burner assembly may further comprise a cooking vessel support structure configured for supporting a cooking vessel , such as a pan or pot , at a predefined level over the combustion burner assembly with a bottom side of the vessel facing the cover . In the assembled state , i . e . when the cooking vessel support structure and combustion burner assembly are arranged according to the desired operation, a maximal distance between the predefined level and the cover may be in the range from 5 mm to 20 mm, preferably from 7 mm to 15 mm, in particular about or around 10 mm . As compared to burners known from the prior art , the distance may be reduced with the suggested burner design, e . g . to about 10 mm, which may be advantageous in terms of efficient heat transfer .

In embodiments , a thickness of the circumferential collar, e . g . a thickness of a wall that defines the collar, and/or a longitudinal length of the depressions , measured transversely to the circumferential collar, for example in radial direction in case of a circular collar, may be in the range from 1 . 5 mm to 18 mm, or 1 . 5 mm to 16 mm . For example , in case of a burner with the cover loosely placed on the burner body and/or with a dimension of the outlet openings in the area of about 1 mm x 1 mm, the thickness or length may be about or around 1 . 5-5 mm ( ± 1 mm) . In case of a burner with the cover attached to the burner body and/or with a dimension of the outlet openings in the area of about 0 . 5 mm x 0 . 5 mm, the thickness or length may be about or around 14 -16 mm

( ± 1-3 mm) .

In view of this , using a cover loosely placed on the burner body is apt for reducing the amount or material needed for manufacturing the burner body, wherein the mentioned range at the same time provides for sufficient mechanical and thermal strength .

Using a design in which the cover is attached to the burner body, the thickness may be larger , and may for example be implemented such that the distal face side of the collar provides sufficient material strength to attach the cover, for example via one or more screws or similar . For example the distal face side , in particular in the region of the flat bearing surfaces , the collar may include screw holes opening towards the second side and matching with corresponding through-holes in the cover such that a respective through-hole is aligned with a respective screw holes in the assembled state . The cover may in this case be attached by screwing a screw into the screw hole thereby firmly attaching the cover to the burner body .

In embodiments , the burner body may be made from aluminum, and the cover may be made from steel . The given material combination has been found to provide sufficient , in particular optimal thermal and mechanical resistance for use with pure hydrogen as the combustion gas . Further , using aluminum for the burner body has been proven advantageous with regard to manufacture using a casting process and/or forming or forging for producing the burner body . Steel has been proven advantageous for the cover in view of thermal and heat durability, workability or machinability, mechanical strength, and/or in terms of obtaining suitable flatness to avoid or at least largely avoid or suppress crosstalk .

Embodiments of the hydrogen combustion burner may be designed in accordance with one of the following dimensions :

According to one embodiment , the hydrogen combustion burner may have a maximal burner power of about 1 kW with a maximal diameter of the circumferential collar being in the range from 35 mm to 60 mm, and/or a number of depressions or flame holes may be in the range from 6 to 12 , in particular 8 ( loosely placed cover ) or 12 ( attached cover ) , and/or a distance between adj acent depressions measured along an outer circumference of the burner body may be in the range from 12 mm to 20 mm, preferably at about 12 . 3 mm ( attached cover ) or 18 . 1 mm ( loosely placed cover) .

According to one embodiment, the hydrogen combustion burner may have a maximal burner power of about 2 kW with a maximal diameter of the circumferential collar being in the range from 60 mm to 80 mm, and/or a number of depressions may be in the range from 7 to 16, preferably 7 to 14, in particular 12 (attached cover) or 16 (loosely placed cover) , and/or a distance between adjacent depressions measured along an outer circumference of the burner body may be in the range from 11 mm to 12 mm, preferably at about 11.8 mm (for both loosely placed cover and attached cover) .

According to one embodiment, the hydrogen combustion burner may have the hydrogen combustion burner may have a maximal burner power of 3.5 kW or more than 3.5 kW with a maximal diameter of the circumferential collar being 85 mm or more than 85 mm, and/or a number of depressions may be in the range from 8 to 28, preferably from 16 to 28, in particular 16 (loosely placed cover) or 28 (attached cover) , and/or a distance between adjacent depressions measured along an outer circumference of the burner body may be in the range from 15 mm to 18 mm, preferably at about 15.5 mm (attached cover) or 17.7 mm (loosely placed cover) .

The above embodiments and given dimensions have been proven to provide good combustion and/or cross-lighting characteristics, and, at the same time, good safety characteristics with regard to the combustion of pure hydrogen. It is to be noted that the objectives mentioned beforehand, i.e. good combustion, good cross-lighting, and good safety, whilst avoiding safety-relevant malfunction, can be obtained for all of the embodiments described herein in connection with the underlying invention .

In embodiments, a gas cooking appliance for the heating of cooking vessels by means of combustion of substantially pure hydrogen is provided . The gas cooking appliance comprises one or more heating zones , wherein at least one , preferably each, heating zone comprises at least one hydrogen combustion burner assembly according to any embodiment described herein in connection with the underlying invention .

In a further embodiment , a method of manufacturing a hydrogen combustion burner assembly according to any embodiment described herein in connection with the underlying invention is provided . The method comprises : manufacturing the burner body in that the burner body, including the cup-shaped recess and depressions , are manufactured in a single casting step or process , and comprising casting the burner body to have a contiguous body void of feedthroughs to the outer atmosphere except for the gas inlet opening and the cup-shaped recess opening to the second side .

The advantage of the suggested burner design and manufacturing method is that the burner body may be manufactured in a comparatively costefficient manner and does not require complex operations , such as for example drilling a plurality of very small holes ( diameter of for example 0 . 2 mm) for the flame ports . Further, using molding may provide efficient manufacture , in particular in terms of large-scale production . In view of this , the suggested method for manufacturing the hydrogen combustion burner, in particular the burner body, is comparatively simple and efficient .

In embodiments , the method may comprise a forging or forming , in particular cold forging or cold forming, process applied to the casted burner body .

In embodiments , the method may comprise providing , in particular manufacturing , the cover , and putting the cover on the distal face side with a lower side of the cover facing the cup-shaped recess and bearing against the flat bearing surfaces , thereby closing the cup-shaped recess and groove-like depressions at the second side to define the gas supply chamber and gas outlet openings acting as flame ports of the hydrogen combustion burner assembly . In view of this , the assembly of the hydrogen combustion burner assembly is comparatively simple .

The method may comprise additional optional steps such as installing an ignition device comprising an igniter, e . g . to the burner body, for example such that the igniter is proximate to at least one flame port defined by the outlet openings .

The method may further comprise installing a cooking vessel support structure , wherein the cooking vessel support structure may comprise a grid and/or a plurality of support elements , such as support arms , proj ecting from a base or pedestal , and to be attached to the burner body and/or a cooktop or cooktop cover plate associated with the burner body . The support structure , in particular the support elements , such as support arms , may be configured to extend, in the installed configuration, substantially parallel to an upper surface of the hydrogen combustion burner assembly .

Further , the method may involve attaching the combustion burner assembly to a cooktop or cooktop cover plate . In particular, the cooktop or cooktop cover plate may include one or more cutouts , respectively for accommodating a hydrogen combustion burner assembly . The hydrogen combustion burner assembly may comprise one or more mounting elements , such as one or more proj ections or one or more flanged proj ections extending radially from the burner body and configured for engaging a corresponding cutout . The mounting elements may be integral with the burner body, and may be formed in the casting step for manufacturing the burner body . As explained above , the suggested hydrogen combustion burner assembly is efficient with regard to the combustion of pure or substantially pure hydrogen, and may be manufactured in a comparatively efficient manner . Further , embodiments of the hydrogen combustion burner may include the cover removably provided on the burner body ( e . g . loosely placed or attached to the burner body) , which may be advantageous with regard to cleaning and maintenance . Further, the removable cover has the advantage of enabling comparatively simple cleaning and maintenance of the gas supply chamber ( cup-shaped recess ) and groove-like depressions , which may be prone to soiling in connection with cooking processes , e . g . overflowing pots and/or food spills etc .

In embodiments , a hydrogen supply line or source may be configured for suppling pure hydrogen or substantially pure hydrogen gas , such gas having at average least 95% , preferentially at least 98% , more preferentially at least 99% , in volume of hydrogen .

In embodiments , the hydrogen combustion burner assembly may comprise a sensor device for detecting correct placement of the cover onto the burner body (which may also be termed main body) . The sensor device may be configured to signal an incorrect placement of the cover, for example in the form of a warning signal . Further the signal may be used by a control unit to interrupt hydrogen delivery to the respective combustion burner .

In embodiments , the hydrogen combustion burner assembly may further comprise an auxiliary cover for placement onto the cover . The auxiliary cover may be configured for protecting the cover and/or may comprise a lining, plating, or finish suitable for adj usting the appearance of the cover to surrounding design aesthetic designs . The auxiliary cover may be advantageous for facilitating manufacture , as it is not required to provide the cover , e . g . manufactured with steel , with a final aesthetic finish . In embodiments , the outlet openings , in particular flame ports , may be arranged equally spaced from one another in circumferential direction of the collar, or about a central axis of the burner body ( or main body) . This may ensure homogenous flame properties and heating .

A non-limiting embodiments of the present invention will now be described, by way of example , with reference to the accompanying drawings . Same or functionally corresponding elements are reference with same reference signs . In the drawings :

- Figure 1 is a schematic sketch of a gas cooking appliance according to the present invention, with parts removed for clarity;

- Figure 2 is a perspective view of a detail of the gas cooking appliance of Figure 1 , in particular showing a first embodiment of a hydrogen combustion burner assembly, with parts removed for clarity;

Figure 3 is a partially exploded perspective view of the detail of Figure 2 , with parts removed for clarity;

- Figure 4 is an enlarged perspective view of a portion of the detail of Figure 2 , with parts removed for clarity;

Figure 5 is a sectioned view of the detail of Figure 2 , with parts removed for clarity;

Figure 6 is a perspective view of a detail of the gas cooking appliance of Figure 1 , in particular showing a second embodiment of a hydrogen combustion burner assembly, with parts removed for clarity;

- Figure 7 is a is a sectioned view of the detail of Figure 6 , with parts removed for clarity; and

Figure 8 is perspective view of a part of the detail of Figure 6 , with parts removed for clarity . With particular reference to Figure 1 , number 1 indicates as a whole a hydrogen gas cooking appliance for the thermal treatment , in particular for the heating and/or cooking, of food products .

In the specific example , reference is made below to a hydrogen gas cooking hob 1 , but alternatively the hydrogen gas cooking appliance could also be a hydrogen gas stove or similar , wherein the below description applies mutatis mutandis to hydrogen gas cooking appliances in general .

In more detail , the hydrogen gas cooking hob 1 , referred to below as gas cooking hob for simplicity, is configured to heat cooking vessels containing food products by combustion of gaseous hydrogen, in particular pure or substantially pure hydrogen .

The food product to be thermally treated may be a single ingredient or a mixture of ingredients . It should also be noted that the food product to be treated may vary throughout the overall thermal treatment process ; i . e . it may be possible to add or remove ingredients to the food product during the thermal treatment . In addition or alternatively, it may also possible that portions of the food product may disappear during the thermal treatment process ( e . g . by means of evaporation or the like ) and/or portions of the food product may be subj ected to physical and/or chemical transformations .

The gas cooking hob 1 comprises one or more heating zones 2 , each one configured to receive a cooking vessel for example containing a food product to be thermally treated and configured to heat the respective cooking vessel and/or the food product present within the respective cooking vessel , by the combustion of gaseous , pure or substantially pure hydrogen .

Preferentially, each cooking zone 2 may comprise at least one , preferentially exactly one , hydrogen combustion burner assembly 3 , as shown and described in detail in connection with figures 2 to 8 .

Each hydrogen combustion burner assembly 3 is configured to allow the combustion of the hydrogen ( in gaseous form) in a controlled manner .

Preferentially, gas cooking hob 1 may also comprise a control unit 4 configured to control , preferentially to selectively control , operation of each heating zone 2 , preferentially the respective hydrogen combustion burner assembly ( ies ) 3 . In the example shown, the control unit 4 or a control interface , comprises one or more control buttons 5 , each one operatively connected to one respective heating zone 2 and being configured to allow a user to selectively control the respective heating zone 2 , preferentially by adj usting a flow rate of the hydrogen to be burned and/or turning on, in particular including igniting, the respective heating zone 2 or hydrogen combustion burner assembly 3 . Alternatively and/or in addition, the control unit 4 may comprise digital , in particular touch-sensitive , voice-controlled, gesture controlled or other , input means for selectively controlling one or more of the heating zones 2 .

According to some preferred non-limiting embodiments , the control unit 4 may comprise or be associated with one or more control valves , each one configured to control the hydrogen flow and passage to one respective hydrogen combustion burner assembly 3 . Further , one or more safety valves may be provided for cutting off or disabling gas supply or for enabling gas supply, e . g . from a gas source , e . g . a container or a gas grid .

The cooking vessel may be of any kind . The cooking vessel could be a pot , a kettle , a pan, a plate , a bowl or the like . The cooking vessel may or may not comprise a respective lid .

In the specific case shown, the gas cooking hob 1 comprises a plurality of heating zones 2 , in particular five . The gas cooking hob 1 could, however , comprise only one heating zone 2 , two , three , four or even more heating zones . Further, the arrangement and shape of the cooking zones as shown is not limiting , wherein the cooking zones may be circular ( as shown ) , oval , ovoid, or may have an elongated and/or oblong shape , e . g . for heating vessels with non-circular footprint .

Preferentially, each heating zone 2 may comprises a support structure ( not shown) configured to carry or support the at least one cooking vessel . According to some possible embodiments , the respective support structure ( s ) of each heating zone 2 may be separable or removably attached to the hob 2 and/or combustion burner assembly 3 . Some or each of the respective support structures may be realized in a single piece .

According to some preferred non-limiting embodiments , the gas cooking hob 1 may also comprise a housing structure 6 and each hydrogen combustion burner assembly 3 may be fitted to and/or carried by housing structure 6 , in particular a cooktop plate , wherein the hydrogen combustion burner assembly 3 may be fitted into a cutout provided in the cooktop plate . Additionally, the housing structure 6 may also comprise the one or more support structures , for example for supporting the hob 1 on a supporting or carrying structure . The hob 1 may be a stand-alone appliance or may be configured for installation or integration into or worktop , or a combined appliance , comprising for example a baking or cooking chamber or muffle .

In the following , the structure and function of a single hydrogen combustion burner assembly 3 will be described, which corresponds to the structure and function of the others having, for example different size or shale .

With particular reference to Figure 2 to 5 , the hydrogen combustion burner assembly 3 comprises a main body or burner body 7 . Preferentially, hydrogen combustion burner assembly 3 may also comprise an inj ection noz zle 9 arranged within the burner body 7 and configured to control the flow of gaseous hydrogen within the burner body 7 .

The burner body 7 is formed as a single piece , e . g . it may be formed as a monoblock, preferably by casting, and, if required forming .

The burner body 7 comprises a gas inlet opening 10 configured to be connected to a hydrogen supply, such as a hydrogen supply line , and a flow channel or passageway 11 being in fluidic connection with the gas inlet opening 10 and configured to receive the hydrogen from the hydrogen supply and through inlet opening 10 . The inj ection noz zle 9 is preferably positioned in the passageway 11 .

Preferentially, the hydrogen supply may be configured to supply pure hydrogen ( i . e . the gas being fed by the hydrogen supply may deliver a gas having at least 95 % , preferentially at least 98% , more preferentially at least 99% , in volume of hydrogen ) .

The inj ection nozzle 9 is in fluidic connection with the gas inlet opening 10 on the one hand and the passageway 11 on the other hand, and is configured to control inj ection of gaseous hydrogen gas into the upstream parts of the passageway 11 and further upstream components of the burner body 7 . In the given examples , the inj ection nozzle 9 is arranged within the passageway 11 .

In the assembled state , the burner body 7 together with a cover 16 to be placed on the burner body 7 define a gas supply chamber 12 , i . e . a chamber formed in the assembled state for distributing and supplying hydrogen gas , entering into the gas supply chamber from the passageway 11 , to flame ports of the hydrogen gas burner assembly 3 . The gas supply chamber 12 is in fluidic communication with the passageway 11 and is configured to receive the gaseous hydrogen through the passageway 11 and to allow for the formation of a hydrogen gas atmosphere within gas supply chamber 12 itself . In the assembled state , a plurality of outlet openings 13 are defined by the cover 16 covering groove-like depressions 27 in the burner body 7 , more precisely in a distal face side of a ring-shaped collar 15 of the burner body 7 , the collar 15 radially and/or laterally delimiting a cup-shaped recess 28 that defines , when covered by the cover , the gas supply chamber 12 .

The outlet openings 13 represent or define flame ports of the hydrogen combustion burner assembly 3 in the operational state , and are in fluidic communication with the gas supply chamber 12 on the one hand and an outer atmosphere 14 of the hydrogen combustion burner assembly 3 on the other hand . The outer atmosphere may, in connection with ordinary operation and use , the air atmosphere . At the flame ports , the hydrogen gas exits the gas supply chamber 12 via the outlet openings 13 and may be ignited, e . g . via an igniter arranged near one or more flame ports . If ignited, the outflowing hydrogen gas burns under oxygen supply from the outer atmosphere .

In particular , the burner body 7 and gas supply chamber 12 are designed such that the hydrogen atmosphere within gas supply chamber 12 can, in operation, contain substantially only the hydrogen inj ected via the passageway 11 , preferentially by the inj ection nozzle 9 .

Preferentially, in use , the hydrogen atmosphere within the gas supply chamber may comprise at least 80% in volume of hydrogen, more preferentially at least 85% in volume of hydrogen, even more preferentially at least 90% of hydrogen, most preferentially at least 95% of hydrogen, even most preferentially substantially 100% hydrogen .

Preferentially, the hydrogen source may be configured to supply pure hydrogen ( i . e . the hydrogen source may deliver a hydrogen gas having at least 95% , preferentially at least 98% , more preferentially at least 99% , in volume of hydrogen; any contaminations are negligible ) .

In particular, the hydrogen combustion burner assembly 3 is , except for the outlet openings 13 and inlet opening 10 , void of any additional apertures , which, in use , could allow entrance of air into the passageway 11 and/or the gas supply chamber 12 , or, more generally speaking, into the internal free volume of the burner body . Accordingly, in use , the gas supply chamber 12 only contains the hydrogen gas supplied via the inlet opening 10 and inj ected via the passageway 11 , preferentially by the inj ection noz zle 9 .

Preferentially, the burner body 7 may be designed such that the gaseous hydrogen that is inj ected into the passageway 11 , passes the passageway 11 and flows directly into the gas supply chamber 12 and from the gas supply chamber 12 through the outlet openings 13 or flame ports to outer atmosphere 14 , where the hydrogen gas is burnt once ignited .

Preferentially, each outlet opening 13 , in particular each depression 27 , may extend from an inlet portion facing the gas supply chamber 12 to an outlet portion facing the outer atmosphere 14 .

In the embodiments shown, the burner body 7 comprises the ring-shaped collar 15 laterally and/or radially delimiting the gas supply chamber 12 , and comprising the plurality of elongated groove-like depressions 27 , wherein each depression 27 at least partially defines one respective outlet opening 13 , and the cup-shaped recess 28 defines , together with the cover 16 , the gas supply chamber 12 , once the cover 16 is placed on the burner body 7 .

With regard to the burner body 7 and/or collar 15 , a longitudinal axis A may be defined, which in the present case represents a kind of central axis of the burner body 7 and/or collar 15 , in particular in view of the overall circular shape of the burner body 7 . The longitudinal axis A extends from a first side SI of the burner body 7 , where the inlet opening 10 is located, to a second side S2 of the burner body 7 , where the cover 16 or outlet openings 13 , or flame ports , respectively, are located . In the examples shown, the longitudinal axis A coincides with a central axis of the passageway 11 .

The collar 15 together with the bottom wall 17 ( or base ) defines the cup-shaped recess 28 , and laterally and/or radially delimits the gas supply chamber 12 , in particular transverse or perpendicular to central axis A.

According to some preferred non-limiting embodiments , the outlet openings 13 , preferentially the respective depressions 27 , which may also be considered as grooves , may be equally spaced apart from each other in circumferential direction relative to the central axis A, i . e . along the circumferential collar 15 .

Moreover, the orifices of the outlet openings 13 are peripherally arranged, and preferentially equally spaced at an outer circumference of the burner body 7 relative to central axis A .

Furthermore , a distal face side of the collar 15 may be considered as divided into a plurality of sections distributed in circumferential direction, wherein a depression 27 is interposed between two respective neighboring sections . Or in other words , each section, which may be a flat bearing surface 20 for bearing against a corresponding flat section of the cover 16 , may be delimited in circumferential direction by two adj acent depressions 27 .

With particular reference to Figures 3 and 5 , the hydrogen combustion burner assembly 3 further comprises the cover 16 arranged on the burner body 7 , preferentially the collar 15 , more preferably on a distal face side of the collar 15 . The distal face side of the collar 15 is given or defined by the crest or crown plane or crest/crown face ( or surface ) of the collar 15 oriented towards the second side S2 . During ordinary use , the first side SI corresponds to a lower side of the burner body 7 , and the second side S2 corresponds to the upper side of the burner body 7 and is intended for heating cooking vessels arranged thereabove . The cover 16 delimits , in cooperation with burner body 7 and/or the collar 15 , the plurality depressions 27 and the cup-shaped recess 28 to define the outlet openings 13 and the gas supply chamber 12 , respectively .

The cover 16 is arranged on the burner body 7 , preferentially the collar 15 , in an air-tight manner ; i . e . such that no unwanted fluidic communication between outer atmosphere 14 and the gas supply chamber 12 , and cross-talk may occur, and such that hydrogen gas may only exit the gas supply chamber 12 to the outer atmosphere 14 through the outlet openings 13 . This contributes to avoiding the formation of a potentially hazardous hydrogen-oxygen mixture within the inner volume of the burner body 7 , i . e . before the outflowing gas is burnt at the flame ports .

The cover 16 delimits and defines together with burner body 7 the gas supply chamber 12 , preferentially in a direction parallel to central axis A. In more detail , the burner body 7 may comprise a bottom wall 17 facing the cover 16 , wherein the bottom wall 17 forms a bottom part of the gas supply chamber 12 .

More specifically, the bottom wall 17 may comprise an aperture 18 and the passageway 11 merges into the aperture 18 . The passageway 11 is implemented as an inner void of the burner body and is in fluidic communication with the aperture 18 , and - via the aperture 18 - in fluidic communication with the gas supply chamber 12 . In use , the gaseous hydrogen flows from the inlet opening 10 through the passageway 11 and the aperture 18 into the gas supply chamber 12 , and from the gas supply chamber 12 into the outlet openings 13 . The passageway 11 may, at least in part , have a circular cross-section .

Preferentially, the passageway 11 may be delimited by a circumferential lateral wall of the burner body 7 and a base or base wall opposed to the aperture 18 . More preferentially, the inj ection noz zle 9 may be fixed on, at or in the region of the base .

In the given example , the inj ection noz zle 9 provides the only fluidic passage for the gaseous hydrogen from the inlet opening 10 the gas supply chamber 12 .

According to some non-limiting embodiments , the cover 16 may be removably arranged on, in particular attached to the burner body ( embodiments according to figures 1 to 5 ) , or may be loosely placed on the burner body 7 , preferentially the collar 15 ( embodiment according to figures 6 to 8 ) .

In further detail , the burner body 7 (which may also be considered a main body of the burner assembly) , preferentially the collar 15 , may comprise an abutment surface 19 . Preferentially, abutment surface 19 may comprise a plurality of flat bearing surfaces 20 or respective flat bearing surface portions ( or simply surface portions ) . As shown in the figures , the flat bearing surfaces 20 are separated by the depressions

27 .

Moreover, one outlet opening 13 , preferentially a respective depression 27 or groove , is be interposed between two respective flat bearing surfaces 20 .

According to some preferred non-limiting embodiments , the abutment surface 19 may lie on the second side S2 of the burner body 7 opposite to first side SI of the burner body 7 (where the inlet opening 10 is located ) , and oriented towards the second side S2 . The abutment surface 19 and the flat bearing surfaces 20 may lie in a first plane substantially perpendicular to central axis A. In particular, each flat bearing surface20 may be perpendicular to central axis A.

Preferentially, an engagement surface 21 of the cover 16, located on a lower side of the cover 16, i.e. a side of the cover 16 facing the burner body 7 in the assembled state, may lie on a second plane perpendicular to central axis A.

According to some preferred non-limiting embodiments, the abutment surface 19, preferentially the flat bearing surfaces 20, and engagement surface 21 may be flat or planar, e.g. respectively with a flatness lower than 0.3 mm.

According to some non-limiting embodiments, the cover 16 may engage with the flat bearing surfaces 20 in an air-tight manner, in particular such that the only fluidic connections between the gas supply chamber 12 and the outer atmosphere 14 is given by the outlet openings 13, and, for example, such that at least cross-talk via the flat bearing surfaces 20 is avoided or prevented. In particular, the formation of putatively hazardous hydrogen-oxygen mixtures before exiting the outlet openings 13 or flame ports can be avoided.

According to some preferred non-limiting embodiments shown in connection with figures 2 to 5, the hydrogen combustion burner assembly 3 may comprise one or more fastening elements 22, in the specific case of figures 1 to 5 exactly four fastening elements 22, provided and applied for fixing or attaching cover 16 to the burner body 7, preferentially to the collar 15.

The fastening elements 22 may be chosen from the group comprising screws, bolts, rivets, or the like.

Preferentially, the fastening elements 22 may be configured to non- permanently, i.e. removably, attach the cover 16 to the burner body 7, preferentially the collar 16 . In other words , the fastening elements 22 may be configured to removably fix the cover 16 to the burner body 7 , preferentially to the collar 16 .

In embodiments , the fastening elements 22 may be removable by only by a technically-trained person . In this way, it may be guaranteed that an untrained user cannot remove the cover 16 and operate the hydrogen combustion burner assembly 3 afterwards in an improper and putatively dangerous manner .

For example , the fastening elements 22 may be removable only by means of a specific tool only available to a technically-trained person .

Alternatively, fastening elements 22 and therewith also the cover 16 may not be removable . Also in this case , the cover 16 and burner body 7 are two separate parts or components .

Preferentially, the fastening elements 22 may also be configured to exert a pressing force onto cover 16 towards and onto the burner body 7 , preferentially the collar 15 and/or abutment surface 19 . Such a pressing force may improve air-tightness between the cover 16 and the collar 15 .

Preferentially, the burner body 7 , preferentially the collar 15 , may comprise a respective seat 23 for each fastening element 22 . For example , each fastening element 22 may comprise a thread and the respective seat 23 may comprise a counter-thread, i . e . in the form of a threaded hole .

According to some preferred non-limiting embodiments , the fastening elements 22 may be equally spaced about the central axis A and/or in circumferential direction of the collar 15 .

The hydrogen combustion burner assembly 3 may further comprise an auxiliary cover 24 placed, preferentially freely or loosely ( i . e . without any fastening means) , onto the cover 16.

With particular reference to Figures 3 and 4, each depression 27 forming in the assembled state an outlet opening 13, has a rectilinear shape and cross section.

Preferentially, a respective length of each depression 27 may range between 8 mm to 18 mm, preferentially between 10 mm to 15 mm. All of the depressions 27 preferably have the same, or substantially the same, length (measured locally perpendicular to the collar 15) .

According to some preferred non-limiting embodiments with the cover 16 attached to the burner body 7 by means of one or more fixing elements, each depression 27 may have a width ranging between 0.3 mm to 0.8 mm, preferentially ranging between 0.4 mm to 0.6 mm. For example, the width may be 0.5 mm x 0.5 mm.

Preferentially, each depression 27 or outlet opening 13 may have a constant width along its full extension across the collar 15. All recesses 27 and outlet openings 13 may have the same dimensions, i.e. substantially the same dimensions within the scope of ordinary manufacturing tolerances of the manufacturing method (s) and processing used .

According to some possible non-limiting embodiments, each hydrogen combustion burner assembly 3 may also comprise a sensor device, preferentially operatively coupled to the control unit 4, and being configured to detect a correct placement of the cover 16 on burner body 7, preferentially on the collar 15.

Preferentially, the sensor device may be configured to signal an incorrect placement of the cover 16 and such that any hydrogen delivery to the passageway 11, preferentially also to injection nozzle 9, may be interrupted, preferentially by the control unit 4. According to some preferred non-limiting embodiments , the control unit

4 may comprise a flame safety device , in particular a flame detector, associated to each heating zone 2 , preferentially so as to interrupt the hydrogen flow to the respective hydrogen combustion burner assembly 3 if a temperature of the respective hydrogen combustion burner assembly 3 is , during use , below a threshold temperature and/or, for example , as soon as no flame is detected after ignition with a supply valve still being open .

The flame safety device may comprise one or more respective temperature sensors 25 , each one associated with one respective hydrogen combustion burner assembly 3 configured to detect a temperature of the respective hydrogen combustion burner assembly 3 . The control unit 4 may be configured to selectively control the control valves provided for controlling hydrogen supply, in dependence of the detected temperatures . In particular, the control unit 4 may be configured to close one or more respective control valves if the detected temperature associated with the respective hydrogen combustion burner assembly 3 is below the threshold temperature .

According to some preferred non-limiting embodiments , each hydrogen combustion burner assembly 3 may also comprise an ignition device 26 ( or ignitor ) , preferentially being operatively connected to control unit 4 , and configured to ignite the gaseous hydrogen exiting from the respective hydrogen combustion burner assembly 3 and through the respective outlet openings 13 , representing flame ports in the operational state .

According to some preferred non-limiting embodiments , each support structure of the cooking appliance 1 for supporting a cooking vessel may be configured such that a distance between the cooking vessel and the respective hydrogen combustion burner assembly 3 may be in a range from

5 mm to 15 mm, for example 10 mm. In particular , the distance between the cooking vessel and the respective hydrogen combustion burner assembly 3 may be defined as the distance , measured in a direction parallel to the central axis A, between a plane coinciding with a bottom surface of the cooking vessel and a plane crossing the outlet openings 13 ( or channels ) or flame ports .

Figures 6 to 8 show a second embodiment of a combustion burner assembly 3 . The combustion burner assembly 3 of the second embodiment differs from the one of figures 2 to 5 , in particular but not limited thereto , in that i ) the cover 16 is loosely placed on the burner body 7 or collar 15 ( i . e . there are no fixing elements provided or required ) , ii ) the thickness T of the collar 15 measured perpendicularly or radially to the longitudinal axis A is lower, and iii ) the depressions 27 forming or defining the outlet openings 13 when covered by the cover 16 have different dimensions .

Specifically, the hydrogen combustion burner assembly 3 according to figures 6 to 8 comprises a burner body 7 with an inner volume for supplying hydrogen gas from a gas inlet opening 10 to a plurality of gas outlet openings 13 . The gas inlet opening 10 is arranged at a first side SI and the outlet openings 13 arranged at a second side S2 of the burner body 7 , opposite the first side SI .

The burner body 7 comprises a cup-shaped recess 28 that is open at the second side S2 ( see figure 8 ) and is defined by a bottom wall 17 ( or base ) and a circumferential collar 15 , which proj ects at the second side S2 from the bottom wall 17 . The collar 15 has a distal face side oriented away from the burner body 7 at the second side S2 , and comprises a plurality of groove-like depressions 27 in the distal face side , traversing the circumferential collar 15 and extending from an inner side of the collar 15 facing the cup-shaped recess 28 to an outer side of the collar 15 averted from the inner wall . The burner body 7 comprises a passageway 11 fluidly connecting the gas inlet opening 10 to the cup-shaped recess 28 and, in the assembled state , to the gas supply chamber 12 .

The burner assembly 3 or burner body 7 comprises a substantially flat cover plate 16 placed on or adapted for placement on the distal face side of the collar 15 , to cover the cup-shaped recess 28 and the depressions 27 at the second side S2 when placed on the collar 15 .

When covered by the cover plate 16 , the depressions 27 define the gas outlet openings 13 , and the cup-shaped recess 28 defines a gas supply chamber 12 . The gas supply chamber 12 is in fluidic communication with the gas inlet opening 10 via the passageway 11 , and with the outlet openings 13 for supplying gaseous hydrogen from the gas inlet opening 10 to the gas outlet openings 13 . The gas outlet openings 13 are in fluidic communication with the gas supply chamber 12 and the outer atmosphere 14 .

The distal face side comprises , respectively between adj acent depressions 27 in circumferential direction, substantially flat bearing surfaces 20 that rest against the cover 16 in the assembled state , and at least suppress hydrogen gas cross-talk .

The burner body 7 is a one-piece part having a continuous inner wall structure that seals the inner free volume including the passageway 11 . The free inner volume is air-tight against the outer atmosphere , except for the gas inlet opening 10 and outlet openings 13 , or if the cover 16 is not placed on the burner body 7 , the aperture 18 .

That means that the inner volume of the burner body 7 extending between the inlet opening 10 and the aperture 18 , as well as the bottom and inner side walls ( except for the depressions 27 ) delimiting the cupshaped recess 28 are airtight against the outer atmosphere 14 . As discussed above, the hydrogen gas burner assembly 3 provides for comparatively easy and efficient, in particular cost efficient, manufacture and good combustion characteristics for pure or substantially pure hydrogen gas .

As mentioned above, the thickness T of the circumferential wall of the collar 15 of the embodiment of figures 6 to 8 is smaller as compared to the embodiments of figures 2 to 5, wherein the collar 15 may have a wall thickness T of about or around 1.5 mm to 5 mm. By this, the burner body 7 may be designed to have less weight and require less material for manufacture as compared to the first embodiment. Further, a preferred cross-sectional size of the depressions 27 or outlet openings 13 may be about or around 1 mm x 1 mm.

Yet further, the number of flame ports or outlet openings 13 may differ from the burner assembly 3 of figures 2 to 5. For example, a burner with maximal burner power of IkW, 2kW, or >3.5kW may have 8, 12, or 16 flame ports, respectively, whereas in the embodiment of figures 2 to 5, the burner assembly, assuming the same maximal burner power, may have 12, 16, or 28 flame ports, respectively.

In addition, again referring to maximal burner powers of IkW, 2kW, and 3.5kW or >3.5kW, an internal pressure in the gas supply chamber 12 at maximal burner power may be, regarding the burner assembly 3 of figures 6 to 8, about or round 0.2 mbar, 0.4 mbar, or 0.55 mbar, whereas the corresponding internal pressure of the burner assembly 3 of figures 2 to 5 may be >1.1 mbar, >2.3 mbar, or >3 mbar.

Diameters of the burner body 7 in the region of the outlet openings 12 for respective maximal burner powers may be 35-60 mm, 60-85 mm, or >85 mm.

The suggested design of the burner body 7 and burner assembly 3 has the advantage , that the burner assembly 3 may be used with conventional cooktop or countertop designs , in particular without requiring or without requiring substantial structural changes of the cooktop or countertop, except for adaption with regard to the supply of gaseous hydrogen .

The cross-sectional view of figure 7 shows that the cover 16 is loosely placed on the burner body 7 , specifically with a lower flat or plan surface region of the cover 16 resting or abutting against the flat bearing surfaces 20 of the collar 15 . The flat surface region of the cover 16 may be implemented as an outer annular ring area, for example , wherein the outer annular ring may be set back towards the first side SI as compared to the adj acent central area, e . g . a radially inner area, of the cover 16 .

A step or shoulder established between the annular ring area and the central area of the cover 16 ( at the side facing the cup-shaped recess 28 in the assembled state ) may engage with protrusions 30 provided on the inner wall of the collar 15 and proj ecting into the gas supply chamber 12 . The protrusions 30 may be designed to ensure proper alignment of the cover 16 when placed on the burner body 7 .

Further , as may be inferred from figure 7 , the passageway 11 may be divided by the inj ection nozzle 9 or a respective valve seat into two sections or volumes , one fluidly communicating with the inlet opening 10 , and one fluidly communicating with the cup-shaped recess 28 or gas supply chamber 12 .

In the given example , the inj ection noz zle 9 is attached to the burner body 7 at a valve seat implemented as a bore located between the two sections of the passageway 11 . The two sections of the passageway 11 are arranged such that the gaseous hydrogen supplied via the inlet opening 10 flows , following the flow-path from the inlet opening 10 to the gas supply chamber 12 , in radial direction relative to the longitudinal axis A ( i . e . transversely to the longitudinal axis A, in the operational state corresponding to the horizontal direction ) , passes the inj ection noz zle 9 , which has a flow direction that is oriented parallel to the longitudinal axis A ( i . e . corresponding to the vertical direction, and directed upwards in the operational state ) , and continues upwards , i . e . parallel to the longitudinal axis A towards the cup-shaped recess 28 or gas distribution chamber 12 .

The inj ection nozzle 9 is configured and adapted to regulate the internal pressure prevailing in the gas supply chamber ( and the adj acent section of the passageway 11 ) , for example to the values given above at the maximal power level .

In the region of the inlet opening 10 , the burner body 7 may comprise an inlet interface for connecting a hydrogen gas supply line ( not shown ) . The inlet interface is schematically indicated in figure 7 by a segment located at the inlet opening 10 having an enlarged cross section as compared to the passageway 11 extending upstream.

The section of the passageway 11 upstream and downstream of the inj ection noz zle 11 may have circular cross sections and diameters that are larger than that of the valve seat . The section upstream the inj ection nozzle 11 or valve seat , in particular , may define or represent a buffer volume for gaseous hydrogen in terms of supplying hydrogen to the gas supply chamber 12 and to the outlet openings 13 . This buffer volume may be provided or selected to reduce possible fluctuations in flame shape etc .

Figure 8 shows a detailed perspective view of a section of the burner body 7 . As may be inferred from figure 8 , the depressions 27 have a rectangular cross section, which is substantially constant over their whole length transversely to the collar 15 . All depressions 27 have substantially the same shape . Further , figure 8 shows that the inj ection nozzle 9 may be installed through the aperture 18 from the second side S2 .

As shown in the figures , the burner body 7 may include an integral flange 31 ( figure 6 ) , which is provided for attaching the burner body 7 to a cutout in a cooktop, and for attaching the temperature sensor 25 and ignition device 26 .

Figure 6 in addition shows mounting brackets 29 , provided for and configured for securing the temperature sensor 25 and ignition device 26 to the flange in a releasable manner , for example . On a note , the mounting brackets are not mounted in the illustration of figure 6 .

Changes may be made to gas cooking appliance 1 and/or hydrogen combustion burner assembly 3 to the extent of exemplary embodiments described above and further above , without departing from the scope of the present invention .

In all , the above discussion reveals that the hydrogen combustion burner assembly as suggested herein achieves the underlying obj ectives .

The underlying invention is , in particular, directed to a hydrogen combustion burner assembly for a gas cooking appliance and configured for the combustion of pure hydrogen, i . e . the invention in particular relates to a pure hydrogen combustion burner assembly, which may also be termed a pure hydrogen gas combustion burner assembly .

The hydrogen combustion burner assembly comprises a burner body with an inner volume for supplying hydrogen gas from a gas inlet opening to a plurality of gas outlet openings ; a cup-shaped recess open at the second side and defined by a circumferential collar having a distal face side oriented away from the burner body, and comprising a plurality of groove-like depressions in the distal face side ; a passageway fluidly connecting the gas inlet opening to the cup-shaped recess ; and a substantially flat cover plate placed on, wherein the burner body is a one-piece part having a continuous inner wall structure that seals the inner volume , except for the gas inlet opening and outlet openings , against the outer atmosphere in an airtight manner .

List of Reference Signs

1 Hydrogen gas cooking appliance

2 Heating zone

3 Hydrogen combustion burner assembly

4 Control unit

5 Control button

6 Housing structure

7 Burner body

9 Inj ection nozzle

10 Gas inlet opening

11 Passageway

12 Gas supply chamber

13 Outlet opening

14 Outer atmosphere

15 Ring-shaped collar

16 Cover

17 Bottom wall

18 Aperture

19 Abutment surface

20 Flat bearing surface 21 Engagement surface

22 Fixing element

23 Seat

24 Auxiliary cover 25 Temperature sensor

26 Ignition device

27 Depression

28 Cup-shaped recess

29 mounting bracket 30 protrusion

31 flange

A Longitudinal axis

SI First side S2 Second side

T Thickness

Claims

1. Hydrogen combustion burner assembly (3) for a gas cooking appliance (1) and configured for the combustion of pure or substantially pure hydrogen, the hydrogen combustion burner assembly (3) comprising a burner body (7) with an inner volume for supplying hydrogen gas from a gas inlet opening (10) to a plurality of gas outlet openings (13) , the gas inlet opening

(10) arranged at a first side (SI) and the outlet openings (13) arranged at a second side (S2) of the burner body (7) , opposite the first side (SI) ; the burner body (7) further comprising: a cup-shaped recess (28) open at the second side (S2) and defined by a bottom wall (17) and a circumferential collar (15) projecting at the second side (S2) ; the collar (15) having a distal face side oriented away from the burner body at the second side, and comprising a plurality of groove-like depressions (27) in the distal face side traversing the circumferential collar (15) and extending from an inner side of the collar (15) facing the cup-shaped recess (28) to an outer side of the collar (15) averted from the inner wall; a passageway (11) fluidly connecting the gas inlet opening (10) to the cup-shaped recess (28) ; and further comprising a substantially flat cover plate (16) placed on or adapted for placement on the distal face side, to cover the cupshaped recess (28) and the depressions (27) at the second side when placed on the burner body, wherein, when covered by the cover plate (16) , the depressions (27) define the gas outlet openings (13) , and the cup-shaped recess (28) defines a gas supply chamber (12) , with the gas supply chamber (12) being in fluidic communication with the gas inlet opening (10) and the outlet openings (13) for supplying gas from the gas inlet opening (10) to the gas outlet openings (13) , and the gas outlet openings (13) being in fluidic communication with the gas supply chamber (12) and the outer atmosphere (14) ; the distal face side comprises, respectively between adjacent depressions (27) in circumferential direction, substantially flat bearing surfaces (20) that rest against the cover plate (16) in the assembled state, and at least suppress hydrogen gas cross-talk between the depressions (27) in circumferential direction and/or transversely to the collar (15) ; and the burner body (7) is a one-piece part having a continuous inner wall structure that seals the inner volume, except for the gas inlet opening (10) and outlet openings (13) , against the outer atmosphere (14) in an airtight manner.

2. The hydrogen combustion burner assembly (3) according to claim 1, wherein the passageway (11) interconnects the gas inlet opening (10) and the cup-shaped recess (28) , wherein the passageway (11) includes a nozzle (9) or a seat for attaching a nozzle (9) , the nozzle (9) adapted to control passage of hydrogen gas from the inlet opening (10) to the gas supply chamber (12) , the nozzle (9) preferably made from brass.

3. The hydrogen combustion burner assembly (3) according to any of the preceding claims, wherein the cover plate (16) is a disc or is disc-shaped, having at least one flat surface, that in the assembled state, bears against the flat bearing surfaces (20) of the distal face side, wherein the cover plate (16) preferably is a flat-shaped disc, wherein the flat bearing surfaces (20) and the flat surface of the cover plate (16) bearing against other in the assembled state respectively preferably have a flatness lower than 0.3 mm.

4. The hydrogen combustion burner assembly (3) according to any of the preceding claims, wherein all depressions (27) or one or more groups of depressions (27) have substantially equal geometric dimensions, in particular substantially the same size, cross section, and length transversely to the circumferential collar ( 15) .

5. The hydrogen combustion burner assembly (3) according to any of the preceding claims, wherein all depressions (27) have a rectangular, preferably square, cross section in planes perpendicular to the longitudinal axis of the depressions (27) transversely to the circumferential collar (15) , and/or wherein the cross section of the depression (27) is substantially constant along its longitudinal axis.

6. The hydrogen combustion burner assembly (3) according to any of the preceding claims, wherein a size of the depressions (27) measured in planes perpendicular to the longitudinal axis of respective depression is in the range given by 0.4 mm x 0.4 mm to 1.4 mm x 1.4 mm, preferably 0.5 mm x 0.5 mm to 1 mm x 1 mm.

7. The hydrogen combustion burner assembly (3) according to any of the preceding claims, wherein, in the assembled state, the cover plate (16) is loosely placed on the burner body (7) , or the cover plate (16) is removably attached, in particular screwmounted, to the burner body (7) .

8. The hydrogen combustion burner assembly (3) according to any of the preceding claims, wherein, in the assembled state, the cover plate (16) laterally projects beyond an outer rim of the circumferential collar (15) or is substantially flush with the outer rim of the circumferential collar (15) .

9. The hydrogen combustion burner assembly (3) according to claim 2, wherein the burner assembly (3) is associated with a specified maximal burner power and the nozzle (9) is configured to regulate the internal pressure in the gas supply chamber (12) , in particular such that a ratio between the internal pressure measured in millibar (mbar) and the maximal burner power measured in Kilowatt (kW) is in the range from 0.1 mbar/kW to 1 mbar/kW, preferably from 0.2 mbar/kW to 0.9 mbar/kW.

10. The hydrogen combustion burner assembly (3) according to any of the preceding claims, further comprising a cooking vessel support structure configured for supporting a cooking vessel at a predefined level over the combustion burner assembly (3) with a bottom side of the vessel facing the cover plate (16) , wherein in the assembled state, a maximal distance between the predefined level and the cover is in the range from 5 mm to 20 mm, preferably from 7 mm to 15 mm, in particular at about 10 mm.

11. The hydrogen combustion burner assembly (3) according to any of the preceding claims, wherein a thickness (T) of the circumferential collar (15) and/or a longitudinal length of the depressions (27) , measured transversely to the circumferential collar (15) , is in the range from 1.5 mm to 18 mm.

12. The hydrogen combustion burner assembly (3) according to any of the preceding claims, wherein the burner body (7) is made from aluminum and/or the cover plate (16) is made from steel.

13. The hydrogen combustion burner assembly according to any of the preceding claims, wherein the hydrogen combustion burner assembly (3)

- has a maximal burner power of about 1 Kilowatt (kW) with a maximal diameter of the circumferential collar (15) being in the range from 35 mm to 60 mm, and/or a number of depressions (27) being in the range from 6 to 12, in particular 8 or 12, and/or a distance between adjacent depressions (27) measured along an outer circumference of the burner body (7) is in the range from 12 mm to 20 mm, preferably at about 12.3 mm or 18.1 mm,

- has a maximal burner power of about 2 Kilowatt with a maximal diameter of the circumferential collar (15) being in the range from 60 mm to 80 mm, and/or a number of depressions (27) being in the range from 7 to 16, preferably 7 to 14, in particular 12 or 16, and/or a distance between adjacent depressions (27) measured along an outer circumference of the burner body (7) is in the range from 11 mm to 12 mm, preferably at about 11.8 mm, or

- the hydrogen combustion burner assembly (3) has a maximal burner power of 3 Kilowatt or more than 3 Kilowatt with a maximal diameter of the circumferential collar (15) being 85 mm or more than 85 mm, and/or a number of depressions (27) being in the range from 8 to 28, preferably from 16 to 28, in particular 16 or 28, and/or a distance between adjacent depressions (27) measured along an outer circumference of the burner body (7) is in the range from 15 mm to 18 mm, preferably at about 15.5 mm or 17.7 mm.

14. Gas cooking appliance (1) for the heating of cooking vessels by means of combustion of substantially pure hydrogen comprising one or more heating zones (2) , wherein at least one, preferably each, heating zone (2) comprises at least one hydrogen combustion burner assembly (3) according to any of the preceding claims .

15. Method of manufacturing a hydrogen combustion burner assembly (3) according to any of claims 1 to 13, comprising

- manufacturing the burner body (7) in that the burner body (7) , including the cup-shaped recess (28) and depressions (27) , are manufactured using a single casting step or process, and comprising casting the burner body (7) to have a contiguous body void of feedthroughs to the outer atmosphere (17) except for the gas inlet opening (10) and the cup-shaped recess (28) opening to the second side (S2) ; and, optionally, further comprising - a forging or forming, in particular cold forging or cold forming, process applied to the casted burner body (7) , and/ or

- providing, in particular manufacturing, the cover plate (16) , and putting the cover plate (16) on the distal face side with a lower side facing the cup-shaped recess (28) and bearing against the flat bearing surfaces (20) , thereby closing the cup-shaped recess (28) and depressions (27) at the second side (S2) to define the gas supply chamber (12) and gas outlet openings (10) acting as flame ports of the hydrogen combustion burner assembly (3) .