The invention pertains to a premix gas burner and a method for manufacturing a premix gas burner. Such premix gas burners are for example used in water heater appliances, e.g. for obtaining hot tap water or for heating buildings.

For premix gas burners, fuel gas is mixed with air or oxygen or another oxidiser gas to form a premix gas. This premixing takes place upstream of an operational burner deck area of the premix gas burner, adjacent to which operational burner deck area combustion of the premix gas takes place. The fuel gas is for example natural gas, methane ethane, propane, butane, all optionally partly mixed with hydrogen, or a mixture of any of these.

The premix gas burner according to the first aspect of the invention comprises a non- cylindrical burner deck unit. Such burner deck units experience variations in thermal expansion and thermal contraction due to the temperature differences, in particular local temperature differences, that occur over time in such burner deck units.

If the burner deck unit is mounted in the burner in a fixed manner, varying material stresses will occur in the burner deck unit over time. This is known to lead to failure due to thermal fatigue. In order to reduce the risk of early failure due to thermal fatigue, it is known to mount burner deck units in a floating manner, so that during use they can move relative to a frame in which they are mounted. This reduces the build-up of material stresses in the burner deck unit.

However, a problem of such floatingly mounted burner deck units is that they sometimes move out of their intended position during use. This may lead to leakage of premix gas along an edge and/or the burner deck unit getting detached from the frame onto which it is mounted in the premix gas burner. In addition, deformation of the burner deck unit may lead to an undesired contact of the burner deck unit with outer parts of the premix gas burner, such as an ignition pin, an ionisation pin or a sensor. This may lead to malfunction of the premix gas burner. These problems appear to be most prominent in flat or shallow burner deck units but are not limited to such burner deck units.

It is the object of the invention to provide a premix gas burner in which at least one of these problems is at least reduced and a method for manufacturing such a gas burner.

The object of the invention is achieved by a premix gas burner, comprising: - a non-cylindrical burner deck unit, comprising a flame support, the flame support comprising:

- an operational burner deck area comprising gas outflow openings, wherein during use adjacent to the operational burner deck area premix gas is combusted after the premix gas has flown through the gas outflow openings, wherein the burner deck unit further comprises:

- a circumferential edge,

- a support portion which is present between the operational burner deck area and a support portion edge which is formed by at least a part of the circumferential edge of the burner deck unit, the support portion having a support portion thickness and extending in a support portion plane which is perpendicular to the support portion thickness,

- a metal frame which is adapted to hold the non-cylindrical burner deck unit, wherein the premix gas burner further comprises a cavity in which at least a part of the support portion of the burner deck unit is arranged, which cavity comprises: a cavity opening through which the at least part of the support portion of the burner deck unit extends into the cavity, and a cavity inner wall, which cavity inner wall comprises: a cavity end wall portion opposite to the cavity opening, and a first cavity wall portion, and a second cavity wall portion which is arranged opposite to the first cavity wall portion, wherein the first cavity wall portion and the second cavity wall portion extend parallel to or at a non-perpendicular angle to the support portion plane, and the cavity end wall portion extends between the first cavity wall portion and the second cavity wall portion, wherein the first cavity wall portion is defined by a cavity delimiting area of the metal frame, wherein the distance between the first cavity wall portion and the second cavity wall portion is larger than the support portion thickness, and wherein - when the frame and the burner deck unit both are at ambient temperature - the support portion extends between the first and the second cavity wall portion over a length which is at least half of the expected thermal contraction of the burner deck unit in the support portion plane when cooling the burner deck unit from maximum operational temperature to ambient temperature, and wherein the cavity end wall portion is spaced apart from the support portion edge by a distance that is at least half of the expected thermal expansion of the burner deck unit in the support portion plane when heating the burner deck unit from ambient temperature to maximum operational temperature. The premix gas burner according to the first aspect of the invention comprises a non- cylindrical burner deck unit and a metal frame.

The non-cylindrical burner deck unit comprises a flame support. The flame support comprises an operational burner deck area. The operational burner deck area comprises gas outflow openings. During use of the premix gas burner, premix gas is combusted adjacent to the operational burner deck area after the premix gas has flown through the gas outflow openings of the operational burner deck area. The operational burner deck area comprises multiple gas outflow openings which are usually arranged in a pattern. The pattern can be formed by holes and/or slots which extend through a metal plate, or by openings between adjacent wires of a woven wire mesh.

The operational burner deck area is the part of the flame support through which in use premix gas flows in order to be combusted. Optionally, outside the operational burner deck area, the flame support may be closed (for example, no holes, slots or the like present, or no openings between adjacent wires of a woven wire mesh) or may comprises openings (for example holes, slots or the like, or openings between adjacent wires of a woven wire mesh).

The burner deck unit further comprises a circumferential edge and a support portion.

The support portion is present between the operational burner deck area and a support portion edge which is formed by at least a part of the circumferential edge of the burner deck unit. The support portion has a support portion thickness and extends in a support portion plane which is perpendicular to the support portion thickness. The support portion is for example integral with the flame support, i.e. may be formed by a part of the flame support. In that case, the circumferential edge of the burner deck unit may be at least partly, optionally entirely, be formed by a circumferential edge of the flame support.

Optionally, multiple support portions are present.

Optionally, the support portion is at least partly formed by a rim that is connected to the flame support. In that case, at least a part of the circumferential edge of the burner deck unit may extend around the outer circumference of the rim.

The premix gas burner according to the first aspect of the invention further comprises a metal frame which is adapted to hold the non-cylindrical burner deck unit. The metal frame may for example be formed by one or more metal plates, e.g. at least one curved metal plate, or may for example be made out of one or more cast and/or machined metal parts, optionally in combination with one or more metal plates.

The metal frame optionally further comprises a mounting plate which is adapted to mount the premix gas burner in an appliance, such as a heating appliance, e.g. a building heater system or a hot tap water system. The premix gas burner according to the first aspect of the invention further comprises a cavity in which at least a part of the support portion of the burner deck unit is arranged.

The cavity comprises a cavity opening and a cavity inner wall. The cavity inner wall comprises a cavity end wall portion, a first cavity wall portion and a second cavity wall portion. The at least part of the support portion of the burner deck unit extends through the cavity opening into the cavity. The cavity end wall portion is located opposite to the cavity opening. The second cavity wall portion is arranged opposite to the first cavity wall portion. The first cavity wall portion and the second cavity wall portion extend parallel to or at a nonperpendicular angle to the support portion plane, and the cavity end wall portion extends between the first cavity wall portion and the second cavity wall portion.

The first cavity wall portion is formed by a cavity delimiting area of the metal frame.

In the premix gas burner according to the first aspect of the invention, the distance between the first cavity wall portion and the second cavity wall portion is larger than the support portion thickness. As a consequence, a clearance is present between the at least part of the support portion which is arranged in the cavity and at least one of the first cavity wall portion and the second cavity wall portion.

In the premix gas burner according to the first aspect of the invention, - when the frame and the burner deck unit both are at ambient temperature - the support portion extends between the first and the second cavity wall portion over a length which is at least half of the expected thermal contraction of the burner deck unit in the support portion plane when cooling the burner deck unit from maximum operational temperature to ambient temperature. Furthermore, when the frame and the burner deck unit both are at ambient temperature, the cavity end wall portion is spaced apart from the support portion edge by a distance that is at least half of the expected thermal expansion of the burner deck unit in the support portion plane when heating the burner deck unit from ambient temperature to maximum operational temperature.

Ambient temperature is the temperature of the burner deck unit when the premix gas burner is not in use. This is for example the expected temperature, e.g. average expected temperature, at the location of the installation in which the premix gas burner is arranged, for example 20°C for an indoors location.

The maximum operational temperature is the maximum temperature of the burner deck unit during normal operation. For example, a common maximum operational temperature when natural gas is used as fuel gas in the premix gas is between 800°C and 975 °C . In other configurations of premix gas burners, a common maximum operating temperature for the burner deck is for example about 600°C. A typical operational temperature for the frame when natural gas is used as fuel gas in the premix gas is for example 400°C - 450 °C. In other configurations of premix gas burners, a common maximum operating temperature for the frame is for example about 200°C - 400°C..

In general, the length over which the support portion extends into the cavity and between the first and the second cavity wall portion will be larger than the distance between the first cavity wall portion and the second cavity wall portion at the side of the cavity facing towards the operational burner deck area of the flame support.

Optionally, the support portion extends into the cavity and between the first and the second cavity wall portion over a length of at least 1 millimeter, optionally over a length of at least 2 millimeters, for example over a length between (and including) 1 millimeter and 10 millimeters, optionally over a length between 1 millimeter and 7 millimeters, e.g over a length between 1.5 millimeter and 5 millimeters.

Optionally, the cavity end wall portion is spaced apart from the support portion edge by a distance that is at least 1 millimeter, optionally over a length of at least 2 millimeters, for example over a length between (and including) 1 millimeter and 10 millimeters, optionally over a length between 1 millimeter and 7 millimeters, e.g over a length between 1.5 millimeter and 5 millimeters.

Optionally, in the premix burner according to the first aspect of the invention, when the frame and the burner deck unit are both at ambient temperature, the support portion extends into the cavity and between the first and the second cavity wall portion over a length with is at least half of the expected thermal contraction of the burner deck unit in the support portion plane in a direction perpendicular to an outer contour of the operational burner deck area at a location adjacent to the support portion (i.e. adjacent to the support portion or the part thereof which extends into the cavity) when cooling the burner deck unit from maximum operational temperature to ambient temperature.

This further increases the reliability of the metal frame holding the burner deck unit in its intended position during use, cooling down and heating up of the burner deck unit.

Optionally, in the premix burner according to the first aspect of the invention, when the frame and the burner deck unit are both at ambient temperature, the support portion extends into the cavity and between the first and the second cavity wall portion over a length with is at least the expected thermal contraction of the burner deck unit in the support portion plane when cooling the burner deck unit from maximum operational temperature to ambient temperature. This also further increases the reliability of the metal frame holding the burner deck unit in its intended position during use, cooling down and heating up of the burner deck unit.

Optionally, in the premix burner according to the first aspect of the invention, when the frame and the burner deck unit are both at ambient temperature, the cavity end wall portion is spaced apart from the support portion edge by a distance that is at least the expected thermal expansion of the burner deck unit in the support portion plane when heating the burner deck unit from ambient temperature to maximum operational temperature.

This also further increases the reliability of the metal frame holding the burner deck unit in its intended position during use, cooling down and heating up of the burner deck unit and reduces the risk of high material stresses in the burner deck unit during use, cooling down and heating up of the burner deck unit.

Optionally, in the premix burner according to the first aspect of the invention, when the frame and the burner deck unit are both at ambient temperature, the support portion extends into the cavity and between the first and the second cavity wall portion over a length which is at least equal to the expected thermal contraction of the burner deck unit in the support portion plane in a direction perpendicular to an outer contour of the operational burner deck area at a location adjacent to the support portion (i.e. adjacent to the support portion or the part thereof which extends into the cavity) when cooling the burner deck unit from maximum operational temperature to ambient temperature.

This also further increases the reliability of the metal frame holding the burner deck unit in its intended position during use, cooling down and heating up of the burner deck unit.

Optionally, in the premix burner according to the first aspect of the invention, when the frame and the burner deck unit are both at ambient temperature, the support portion extends into the cavity and between the first and the second cavity wall portion over a length with is at least equal to the expected thermal contraction of the burner deck unit in the support portion plane when cooling the burner deck unit from maximum operational temperature to ambient temperature plus the support portion thickness.

This also further increases the reliability of the metal frame holding the burner deck unit in its intended position during use, cooling down and heating up of the burner deck unit.

Optionally, in the premix burner according to the first aspect of the invention, when the frame and the burner deck unit are both at ambient temperature, the support portion extends into the cavity and between the first and the second cavity wall portion over a length with is at least equal to the expected thermal contraction of the burner deck unit in the support portion plane in a direction perpendicular to an outer contour of the operational burner deck area at a location adjacent to the support portion (i.e. adjacent to the support portion or the part thereof which extends into the cavity) when cooling the burner deck unit from maximum operational temperature to ambient temperature plus the support portion thickness.

This also further increases the reliability of the metal frame holding the burner deck unit in its intended position during use, cooling down and heating up of the burner deck unit.

Optionally, in the premix burner according to the first aspect of the invention, the cavity is delimited by the metal frame on at least two sides of the cavity. For example, the first cavity wall portion and the end cavity wall portion are formed by the metal frame.

In the premix burner according to the first aspect of the invention, the burner deck unit is supported in the cavity. Because the distance between the first cavity wall portion and the second cavity wall portion is larger than the support portion thickness (and therefore a clearance is present between the at least part of the support portion which is arranged in the cavity and at least one of the first cavity wall portion and the second cavity wall portion), the support portion of the burner deck unit can move relative to the metal frame when the burner deck unit experiences thermal expansion or thermal contraction due to temperature changes in the burner deck unit which occur e.g. during start-up, normal operation (including modulating operation) and shut down.

The distance between the support portion edge and the cavity end wall portion allows the burner deck unit to expand freely when the temperature of the burner deck unit increases.

Surprisingly, it was found that in most of the case, the support portion did not become stuck in the cavity, which would have prevented movement of the support portion of the burner deck unit within the cavity, even when clearance was chosen small enough to prevent undesired leakage of premix gas along at a point along the circumferential edge of the burner deck unit.

Furthermore, the length over which in accordance with the invention the support portion extends in the cavity and between the first and the second cavity wall portion prevents that the burner deck unit gets dislocated from the metal frame that holds the burner deck unit. During operation of the premix gas burner, in particular during modulation, temperature differences may arise between the burner deck unit and the frame. For example, the burner deck unit may heat up or cool down faster than the frame. It was found that the length over which the support portion extends into the cavity between the first cavity wall portion and the second cavity wall portion over a length in accordance with the first aspect of the invention reduces that problem of the burner deck unit getting dislocated from the frame, or even prevents this problem entirely. In an embodiment, the cavity inner wall is further defined by a counter plate opposite to the cavity delimiting area of the frame and a spacer which is arranged between the cavity delimiting surface of the frame and the counter plate. In this embodiment, the counter plate defines the second cavity wall portion, and the spacer defines the cavity end wall portion.

Optionally, the counter plate is connected to the metal frame, e.g. by a weld (e.g. one or more spotwelds), or by rivets and/or bolts. Alternatively, the counter plate is integral with the metal frame.

Optionally, the spacer is connected to the metal frame, e.g. by a weld (e.g. one or more spotwelds), or by one or more rivets and/or bolts. Alternatively, the spacer is integral with the metal frame.

Optionally, the counter plate is connected to the spacer, and the spacer is in turn connected to the metal frame.

Optionally, the spacer is clamped between the metal frame and the counter plate.

Optionally, the counter plate and the spacer are both integral with the metal frame.

Optionally, the counter plate and/or the spacer are made of individual parts as such, but form part of the metal frame.

Optionally, the counter plate and/or the spacer are made of metal, e.g. steel, stainless steel or aluminium. Alternatively, the counter plate and/or the spacer are made of a resin, e.g. a fibre reinforced resin.

This embodiment provides a practical way of carrying out the invention, which allows for relatively easy manufacturing.

In an embodiment, the flame support has an inner face opposite to the operational burner deck area and the premix gas burner further comprises a gas distributor plate, which gas distributor plate is arranged adjacent to and spaced apart from the inner face of the flame support. In this embodiment, a part of the gas distributor plate defines the second cavity wall portion.

A gas distributor plate provides an even flow of premix gas to the operational burner deck area of the burner deck unit. In order to function well, the gas distributor plate is arranged upstream of the burner deck unit, as seen in the direction of the flow of premix gas.

Due to this upstream arrangement of the gas distributor plate, a part of the gas distributor plate can be used to define the second cavity wall portion or a part thereof. This limits the number of parts that is necessary to make the premix gas burner.

Optionally, the cavity inner wall is defined by the gas distributor plate on at least two sides of the cavity. For example, the second cavity wall portion and an end cavity wall portion are formed by the gas distributor plate. Optionally, the cavity is defined by the metal frame on at least two sides of the cavity. For example, the first cavity wall portion and the end cavity wall portion are formed by the metal frame.

In an embodiment, the distance between the part of the support portion which is present in the cavity and the first cavity wall portion is 0.05 mm - 2.5 mm (mm being millimeters), optionally 0.2 mm - 1.0 mm, for example 0.4 mm, and/or the distance between the part of the support portion which is present in the cavity and the second cavity wall portion is 0.05 mm - 2.5 mm, optionally 0.2 mm - 1.0 mm, for example 0.4 mm.

Optionally, the support portion thickness is 0.6 mm - 1.2 mm and the distance between the part of the support portion which is present in the cavity and the first cavity wall portion is 0.05 mm - 2.5 mm, optionally 0.2 mm - 1.0 mm, for example 0.4 mm, and/or the distance between the part of the support portion which is present in the cavity and the second cavity wall portion is 0.05 mm - 2.5 mm, optionally 0.2 mm - 1.0 mm, for example 0.4 mm.

Optionally, the average distance between the first cavity wall portion and the second cavity wall portion is 1.0 mm - 3.0 mm, for example 1.0 mm - 2.0 mm, optionally 1.0 -1.2 mm.

Optionally, the support portion thickness is 0.4 mm - 1.2 mm, for example 0.6 mm - 1.2 mm, and the average distance between the first cavity wall portion and the second cavity wall portion is 1.0 mm - 3.0 mm, for example 1.0 mm - 2.0 mm, optionally 1.0 -1.2 mm.

Optionally, the distance between the first cavity wall portion I and the second cavity wall portion is between 1.2 times and 1.6 times the support portion thickness.

Optionally, the support portion thickness is 0.4 mm - 1.2 mm, for example 0.6 mm - 1.2 mm, and the distance between the first cavity wall portion and the second cavity wall portion is 1.2 times - 1.6 times the support portion thickness.

Optionally, the support portion thickness is 1.2mm - 2.0 mm, and the distance between the first cavity wall portion and the second cavity wall portion is 1.1 times - 2.0 times the support portion thickness, for example 1.1 times - 1.5 times the support portion thickness, optionally 1.1 times - 1.4 times the support portion thickness.

The average distance between the first cavity wall portion and the second cavity wall portion refers to the average distance between the first cavity wall portion and the second cavity wall portion over the length and/or width of the cavity. For example, when the first cavity wall portion and the second cavity wall portion are parallel to each other, the distance between the first cavity wall portion and the second cavity wall portion is the same at every location within the cavity. However, if the first cavity wall portion and the second cavity wall portion are not parallel to each other, and for example extend at an angle of e.g. 5° - 30° relative to each other in order to provide a relatively wide cavity opening which allows for easy entry of the support portion or for reduces material stresses in the support portion at the location of the support portion at the cavity opening, the distance between the first and second cavity wall portion may vary over the length and/or width of the cavity.

In this embodiment, the cavity is rather narrow. An advantage of this embodiment is that the risk of leakage of premix gas along the circumferential edge of the burner deck unit and/or the support area is reduced. Surprisingly, it was found that the narrow cavity does not or hardly affect the ability of the support portion to move within the cavity in order to allow thermal expansion or thermal contraction of the burner deck unit, even in the case where in the support portion comprises for example an end portion of a woven wire mesh.

In an embodiment, the flame support is or comprises a woven wire mesh. The woven wire mesh comprises a plurality of metal mesh wires, and gas outflow openings are formed by adjacent metal mesh wires.

For example, the woven wire mesh comprises or is made out of metal weft wires and metal warp wires, which warp wires and weft wires optionally extend perpendicular to each other. Optionally, the flame support and/or the operational burner deck area has at least one straight edge, and the warp wires extend perpendicular to this straight edge and the weft wires extend parallel to this straight edge. Alternatively, the flame support and/or the operational burner deck area has at least one straight edge, and the weft wires extend perpendicular to this straight edge and the warp wires extend parallel to this straight edge. Alternatively, the flame support and/or the operational burner deck area has at least one straight edge, and both the warp wires and the weft wires extend at an angle to this straight edge. Optionally, both the warp wires and the weft wires extend at an angle of 45° to this straight edge.

Woven wire mesh is known material for a flame support of a premix gas burner. However, when the woven wire mesh for the flame support is cut from bulk woven wire mesh, sharp edges and/or burrs can be formed on the locations where the wires (e.g. warp wires and/or weft wires) are cut through. Such sharp edges or burrs may inhibit the ability of the support portion to move within the cavity under the influence of thermal expansion or thermal contraction, in particular if the support portion is also formed of the woven wire mesh. However, surprisingly it was found that this does not or hardly occur in the premix gas burner according to the first aspect of the invention.

In case it is desired to further reduce the risk that the support portion gets stuck in the cavity during use of the premix gas burner, the support portion or each support portion may be formed by a rim which is connected to the flame support. Alternatively or in addition, at least a part of an edge of the woven wire mesh may be folded back over the woven wire mesh, in particular if that part of the woven wire mesh forms part of the support portion. In an embodiment, the flame support is or comprises a metal plate, and the metal plate comprises a plurality of holes, and gas outflow openings are formed by the holes.

The holes extend through the metal plate in the direction of the plate thickness. The holes can for example be round, or slot-shaped.

A metal plate with holes is a known material for a flame support of a premix gas burner. Tests have shown that it is compatible with the design of the premix gas burner according to the first aspect of the invention. In addition, a metal plate with holes is easy to manufacture with any desired outer contour of the plate, e.g. by laser cutting. The holes are for example made by laser cutting as well, or by punching. The flexibility with respect to the outer contour allows to easily make the support portion or support portions integral with the flame support.

The metal plate is for example made of stainless steel or aluminium.

In an embodiment, at least a part of the flame support extends in a flat or curved plane. For example, the operational burner deck area extends in a flat or curved plane.

Optionally, the flame support and/or the operational burner deck area is round, elliptical, rectangular, square, hexagonal or octagonal.

Optionally, in case of the flame support in its entirety extending in a curved plane, the height of the flame support is 50 % or less of the width and/or length, or diameter of the flame support. Optionally, the height of the flame support is 30% or less of the width and/or length, or of the diameter of the flame support.

Optionally, in case of a part of the flame support extending in a curved plane, the height of that curved part of the flame support is 50 % or less of the width and/or length, or diameter of that curved part of the flame support. Optionally, the height of the flame support is 30% or less of the width and/or length, or of the diameter of that curved part of the flame support.

Optionally, in case of the operational burner deck area extending in a curved plane, the height of the operational burner deck area is 50 % or less of the width and/or length, or diameter of the operational burner deck area. Optionally, the height of the operational burner deck area is 30% or less of the width and/or length, or of the diameter of the operational burner deck area.

For example, the premix burner according to the first aspect of the invention comprises a flat or shallow burner deck unit comprising the flame support which extends partly or entirely in a flat or curved plane.

Optionally, in this embodiment, the metal frame further comprises a mounting surface for mounting the premix gas burner in an appliance, the mounting surface extending in a mounting plane. Optionally, at least one edge of the flame support and/or of the operational burner deck area extends at an angle of 0° - 45° (both 0° and 45° included) relative to the mounting plane, optionally at an angle of 0° - 30° (both 0° and 30° included) relative to the mounting plane.

In practice, in a premix gas burner of this type, the problem of the burner deck unit moving out of its intended position during use seems to be most prominent (although it happens in other shapes of burner deck units too). Therefore, for this type of premix gas burner, the invention seems to be particularly advantageous.

In an embodiment, the frame further comprises a mounting plate which is adapted to mount the premix gas burner in an appliance, e.g. in a heating appliance.

Optionally, the mounting plate forms a mounting surface, which extends in a mounting plane.

Optionally, at least one edge of the flame support and/or at least one edge of the operational burner deck area extends at an angle of 0° - 45° (both 0° and 30° included) relative to the mounting plate, optionally at an angle of 0° - 30° (both 0° and 30° included) relative to the mounting plate.

In an embodiment, the first cavity wall portion and/or the second cavity wall portion extends parallel or at an angle of 30° or less relative to the support portion plane.

This embodiment provides a relatively wide cavity opening which allows for easy entry of the support portion or for reduces material stresses in the support portion at the location of the support portion at the cavity opening

In an embodiment, the support portion is formed by the flame support, or by a rim which is connected to the flame support.

The rim is optionally made of a metal plate which is connected to the flame support. Optionally, the metal plate is folded and an edge of the flame support is arranged, e.g. clamped, between two parts of the metal plate which are folded over each other.

Optionally, when the support portion is formed by the flame support.

Optionally, when the support portion is formed by the flame support, the support portion is made of a single layer of the material of the flame support. Alternatively, the support portion is at least partly formed by a double layer of the material of the flame support, e.g. by folding the material of the flame support back over itself at the location of the support portion.

This embodiment provides a practical way of implementing the invention.

The invention further pertains to a water heater device comprising a premix gas burner according to any of the preceding claims. The water heater device for example forms part of a heating appliance, a building heater appliance and/or a hot tap water appliance.

The first aspect of the invention further pertains to a method for manufacturing a premix burner according to the first aspect of the invention.

In a first variant of the method according to the first aspect of the invention, the method comprises the following steps: which method comprises the following steps:

- folding a metal plate over a primary fold line, wherein the metal plate has a plate thickness and comprises at least two tabs on a first side of the metal plate, which tabs each extend from a tab base to a tab top, wherein the tab base is located at a distance from the primary fold line, which distance is larger than twice the plate thickness plus the support portion thickness, and the tab top which is further away from the primary fold line than the tab base, by the folding creating a primary portion of the metal plate which is arranged at an angle relative to a secondary portion of the metal plate, the primary portion being arranged on a first side of the primary fold line and the secondary portion being arranged at a second side of the primary fold line, the first side and the second side being opposite to each other, and the secondary portion comprising the tabs,

- arranging at least a part of the support portion of the burner deck unit adjacent to and/or onto the primary portion of the metal plate,

- folding the secondary portion of the metal plate over a secondary fold line by using a punch with a predetermined stroke length, wherein the secondary fold line is arranged at the tab bases, such that the tabs come to extend over at least a part of the support portion of the burner deck unit and the tabs become arranged at an angle relative to the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line, thereby creating at least a part of the cavity inner wall of the cavity of the premix burner according to the first aspect of the invention, with the primary portion of the metal plate defining one of the first cavity wall portion or the second cavity wall portion, the tabs defining the other one of the first cavity wall portion or the second cavity wall portion, and the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining the cavity end wall portion.

Optionally, the method steps are carried out in the order as listed above.

In a second variant of the method according to the first aspect of the invention, the method comprises the following steps: - folding a metal plate over a primary fold line, wherein the metal plate has a plate thickness and comprises at least two tabs on a first side of the metal plate, which tabs each extend from a tab base to a tab top, wherein the tab base is located at a distance from the primary fold line, which distance is larger than twice the plate thickness plus the support portion thickness, and the tab top which is further away from the primary fold line than the tab base, by the folding creating a primary portion of the metal plate which is arranged at an angle relative to a secondary portion of the metal plate, the primary portion being arranged on a first side of the primary fold line and the secondary portion being arranged at a second side of the primary fold line, the first side and the second side being opposite to each other, and the secondary portion comprising the tabs,

- arranging at least a part of the support portion of the burner deck unit adjacent to and/or onto the primary portion of the metal plate,

- folding the secondary portion of the metal plate over a secondary fold line by using a punch with a predetermined stroke length, wherein the secondary fold line is arranged at the tab bases, such that the tabs come to extend parallel to but not overlapping with the at least a part of the support portion of the burner deck unit and the tabs become arranged at an angle relative to the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line, thereby creating at least a part of the cavity inner wall of the cavity of the premix burner according to the first aspect of the invention, with the primary portion of the metal plate defining the first cavity wall portion or the second cavity wall portion and the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining the cavity end wall portion.

Optionally, the method steps are carried out in the order as listed above.

In a third variant of the method according to the first aspect of the invention, the method comprises the following steps:

- folding a metal plate over a primary fold line, wherein the metal plate has a plate thickness and comprises at least two tabs on a first side of the metal plate, which tabs each extend from a tab base to a tab top, wherein the tab base is located at a distance from the primary fold line, which distance is larger than twice the plate thickness plus the support portion thickness, and the tab top which is further away from the primary fold line than the tab base, by the folding creating a primary portion of the metal plate which is arranged at an angle relative to a secondary portion of the metal plate, the primary portion being arranged on a first side of the primary fold line and the secondary portion being arranged at a second side of the primary fold line, the first side and the second side being opposite to each other, and the secondary portion comprising the tabs,

- arranging at least a part of the support portion of the burner deck unit adjacent to and/or onto the tabs of the metal plate, not extending past the bases of the tabs,

- folding the secondary portion of the metal plate over a secondary fold line by using a punch with a predetermined stroke length, wherein the secondary fold line is arranged at the tab bases, such that the tabs come to extend over at least a part of the support portion of the burner deck unit and the tabs become arranged at an angle relative to the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line, thereby creating at least a part of the cavity inner wall of the cavity of the premix burner according to the first aspect of the invention between the primary portion of the metal plate and the tabs of the metal plate, with the tabs of the metal plate defining the first cavity wall portion or the second cavity wall portion and the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining the cavity end wall portion.

Optionally, the method steps are carried out in the order as listed above.

The three variants of the method according to the first aspect of the invention differ from each other in the relative position of the tabs and the primary portion of the metal plate after carrying out the method steps, and in position in which the support portion in arranged relative to the metal plate in the method. Therewith, the three variants of the method each allow to manufacture a different embodiment of premix gas burner according to the first aspect of the invention.

The three variants of the method according to the first aspect of the invention provide a reliable way of mounting a support portion of a burner deck unit with a clearance in a cavity, with a clearance being present between the support portion of the burner deck unit and a first and/or second cavity wall portion of the premix gas burner according to the invention. The tab base being located at the distance from the primary fold line which is larger than twice the plate thickness plus the support portion thickness makes that there is sufficient space to accommodate the support portion in the cavity with the clearance.

The provision of the tabs in the metal plate to be folded defines the position on the second fold line accurately, so that the height of the cavity, i.e. the distance between the first cavity wall portion and the second cavity wall portion, is accurately defined.

The predefined stroke length of the punch also contributes to obtaining an accurate height of the cavity. While in known manufacturing methods for premix gas burners forcelimited punches are used to mount a premix burner element such as a flame support into a cavity, the use of a punch with a predefined stroke length instead makes that the end point of the stroke of the punch is accurately known beforehand, so that the movement of the punch stops at the correct position to obtain the desired cavity height.

When using the method according to the first aspect of the invention, in any of its variants as described above, no or hardly any dimples form when the tabs are folded over the secondary fold line. This results in an accurately formed cavity in which the support portion or support portions of the burner deck unit are arranged. This reduces the risk of leakage of premix gas via the cavity.

In an embodiment, the primary fold line and/or secondary fold line is a straight line. Alternatively, the primary fold line and/or secondary fold line is a straight line.

In an embodiment, the metal plate is folded over the primary fold line such that after this folding, the angle between the primary portion of the metal plate and the secondary portion of the metal plate is between 80° and 100°, optionally 90°.

In an embodiment, the secondary portion of the metal plate is folded over the secondary fold line such that after this folding, the angle between the tabs and the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line is between 80° and 100°, optionally 90°. This results in the tabs and/or the primary portion of the metal plate coming to extend over at least a part of the support portion of the burner deck unit.

In an embodiment, the metal plate is folded over the primary fold line and the secondary portion of the metal plate is folded over the secondary fold line such that after this folding, the tab and the primary portion of the metal plate extend parallel to each other or at an angle of 30° or less.

The second aspect of the invention pertains to a method for manufacturing a premix burner.

In a first variant of the method according to the second aspect of the invention, the method comprises the following steps: which method comprises the following steps:

- folding a metal plate over a primary fold line, wherein the metal plate has a plate thickness and comprises at least two tabs on a first side of the metal plate, which tabs each extend from a tab base to a tab top, wherein the tab base is located at a distance from the primary fold line, which distance is larger than twice the plate plus the thickness of a premix gas burner element which is to be supported by the metal plate, and the tab top which is further away from the primary fold line than the tab base, by the folding creating a primary portion of the metal plate which is arranged at an angle relative to a secondary portion of the metal plate, the primary portion being arranged on a first side of the primary fold line and the secondary portion being arranged at a second side of the primary fold line, the first side and the second side being opposite to each other, and the secondary portion comprising the tabs,

- arranging at least a part of the premix gas burner element of the burner deck unit adjacent to and/or onto the primary portion of the metal plate,

- folding the secondary portion of the metal plate over a secondary fold line by using a punch with a predetermined stroke length, wherein the secondary fold line is arranged at the tab bases, such that the tabs come to extend over at least a part of the premix gas burner element of the burner deck unit and the tabs become arranged at an angle relative to the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line, thereby creating at least a part of a cavity inner wall of a cavity of a premix burner in which cavity the premix gas burner element is to be arranged, with the primary portion of the metal plate defining one of a first cavity wall portion or a second cavity wall portion, the tabs defining the other one of the first cavity wall portion or the second cavity wall portion, and the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining a cavity end wall portion.

Optionally, the method steps are carried out in the order as listed above.

In a second variant of the method according to the second aspect of the invention, the method comprises the following steps:

- folding a metal plate over a primary fold line, wherein the metal plate has a plate thickness and comprises at least two tabs on a first side of the metal plate, which tabs each extend from a tab base to a tab top, wherein the tab base is located at a distance from the primary fold line, which distance is larger than twice the plate thickness plus the thickness of a premix gas burner element which is to be supported by the metal plate, and the tab top which is further away from the primary fold line than the tab base, by the folding creating a primary portion of the metal plate which is arranged at an angle relative to a secondary portion of the metal plate, the primary portion being arranged on a first side of the primary fold line and the secondary portion being arranged at a second side of the primary fold line, the first side and the second side being opposite to each other, and the secondary portion comprising the tabs,

- arranging at least a part of the premix gas burner element of the burner deck unit adjacent to and/or onto the primary portion of the metal plate, - folding the secondary portion of the metal plate over a secondary fold line by using a punch with a predetermined stroke length, wherein the secondary fold line is arranged at the tab bases, such that the tabs come to extend parallel to but not overlapping with the at least a part of the premix gas burner element of the burner deck unit and the tabs become arranged at an angle relative to the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line, thereby creating at least a part of the cavity inner wall of the cavity of a premix burner in which cavity the premix gas burner element is to be arranged, with a primary portion of the metal plate defining the first cavity wall portion or a second cavity wall portion and the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining a cavity end wall portion.

Optionally, the method steps are carried out in the order as listed above.

In a third variant of the method according to the second aspect of the invention, the method comprises the following steps:

- folding a metal plate over a primary fold line, wherein the metal plate has a plate thickness and comprises at least two tabs on a first side of the metal plate, which tabs each extend from a tab base to a tab top, wherein the tab base is located at a distance from the primary fold line, which distance is larger than twice the plate thickness plus the thickness of a premix gas burner element which is to be supported by the metal plate, and the tab top which is further away from the primary fold line than the tab base, by the folding creating a primary portion of the metal plate which is arranged at an angle relative to a secondary portion of the metal plate, the primary portion being arranged on a first side of the primary fold line and the secondary portion being arranged at a second side of the primary fold line, the first side and the second side being opposite to each other, and the secondary portion comprising the tabs,

- arranging at least a part of the premix gas burner element of the burner deck unit adjacent to and/or onto the tabs of the metal plate, not extending past the bases of the tabs,

- folding the secondary portion of the metal plate over a secondary fold line by using a punch with a predetermined stroke length, wherein the secondary fold line is arranged at the tab bases, such that the tabs come to extend over at least a part of the premix gas burner element of the burner deck unit and the tabs become arranged at an angle relative to the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line, thereby creating at least a part of the cavity inner wall of the of a premix burner in which cavity the premix gas burner element is to be arranged between the primary portion of the metal plate and the tabs of the metal plate, with the tabs of the metal plate defining a first cavity wall portion or a second cavity wall portion and the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining a cavity end wall portion.

Optionally, the method steps are carried out in the order as listed above.

In all three methods according to the second aspect of the invention, the cavity that is created in the method according comprises a cavity opening and a cavity inner wall. The cavity inner wall comprises a cavity end wall portion, a first cavity wall portion and a second cavity wall portion. The at least part of the support portion of the burner deck unit extends through the cavity opening into the cavity. The cavity end wall portion is located opposite to the cavity opening. The second cavity wall portion is arranged opposite to the first cavity wall portion. The first cavity wall portion and the second cavity wall portion extend parallel to or at a non-perpendicular angle to the support portion plane, and the cavity end wall portion extends between the first cavity wall portion and the second cavity wall portion.

The three variants of the method according to the second aspect of the invention differ from each other in the relative position of the tabs and the primary portion of the metal plate after carrying out the method steps, and in position in which the premix gas burner element in arranged relative to the metal plate in the method. Therewith, the three variants of the method each allow to manufacture a different embodiment of premix gas burner according to the second aspect of the invention.

The three variants of the method according to the second aspect of the invention provide a reliable way of mounting a premix gas burner element of a burner deck unit with a clearance in a cavity, the clearance being present between the premix gas burner element of the burner deck unit and a first and/or second cavity wall portion of the premix gas burner. The tab base being located at the distance from the primary fold line which is larger than twice the plate thickness plus thickness of the premix gas burner element makes that there is sufficient space to accommodate the premix gas burner element in the cavity with the clearance.

The provision of the tabs in the metal plate to be folded defines the position on the second fold line accurately, so that the height of the cavity, i.e. the distance between the first cavity wall portion and the second cavity wall portion, is accurately defined.

The predefined stroke length of the punch also contributes to obtaining an accurate height of the cavity. While in known manufacturing methods for premix gas burners forcelimited punches are used to mount a premix burner element such as a flame support into a cavity, the use of a punch with a predefined stroke length instead makes that the end point of the stroke of the punch is accurately known beforehand, so that the movement of the punch stops at the correct position to obtain the desired cavity height.

When using the method according to the second aspect of the invention, in any of its variants as described above, no or hardly any dimples form when the tabs are folded over the secondary fold line. This results in an accurately formed cavity in which the premix gas burner element of the burner deck unit are arranged. This reduces the risk of leakage of premix gas via the cavity.

In an embodiment, the primary fold line and/or secondary fold line is a straight line. Alternatively, the primary fold line and/or secondary fold line is a straight line.

In an embodiment, the metal plate is folded over the primary fold line such that after this folding, the angle between the primary portion of the metal plate and the secondary portion of the metal plate is between 80° and 100°, optionally 90°.

In an embodiment, the secondary portion of the metal plate is folded over the secondary fold line such that after this folding, the angle between the tabs and the part of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line is between 80° and 100°, optionally 90°. This results in the tabs and/or the primary portion of the metal plate coming to extend over at least a part of the premix gas burner element of the burner deck unit.

In an embodiment, the metal plate is folded over the primary fold line and the secondary portion of the metal plate is folded over the secondary fold line such that after this folding, the tab and the primary portion of the metal plate extend parallel to each other or at an angle of 30° or less.

In an embodiment, the premix burner element is a burner deck, a flame support, a burner deck unit or a support portion of a burner deck unit.

The invention will be described in more detail below under reference to the drawing, in which in a non-limiting manner exemplary embodiments of the invention will be shown. The drawing shows in:

Fig. 1 : schematically, an embodiment of a premix gas burner according to the first aspect of the invention,

Fig. 2: schematically, a first example of a burner deck unit for a premix gas burner according to the first aspect of the invention, Fig. 3: schematically, a second example of a burner deck unit for a premix gas burner according to the first aspect of the invention,

Fig. 4: schematically, a first embodiment of the premix gas burner according to the first aspect of the invention, shown in part and in cross section,

Fig. 5: schematically, a second embodiment of the premix gas burner according to the first aspect of the invention, shown in part and in cross section,

Fig. 6: schematically, a third embodiment of the premix gas burner according to the first aspect of the invention, shown in part and in cross section,

Fig. 7: schematically, a fourth embodiment of the premix gas burner according to the first aspect of the invention, shown in part and in cross section,

Fig. 8: schematically, an example of a plate as can be used in the method according to first aspect of the invention and/or a method according to the second aspect of the invention,

Fig. 9a and fig. 9b: schematically, an illustration of steps of an embodiment of the first variant of a method according to the first aspect of the invention and/or the second aspect of the invention

Fig. 10a and Fig. 10b show steps in an embodiment of the second variant of the method according to the first aspect of the invention and/or the second variant of the method according to the second aspect of the invention,

Fig. 11a and Fig. 11b show steps in an embodiment of the third variant of the method according to the first aspect of the invention and/or the third variant of the method according to the second aspect of the invention.

Fig. 1 shows, schematically, an embodiment of a premix gas burner 1 according to the first aspect of the invention.

The premix gas burner 1 comprises a non-cylindrical burner deck unit 10 and a metal frame 20. The metal frame 20 comprises a mounting plate 21 which allows the premix gas burner 1 to be mounted in an appliance, e.g. a heating appliance.

For a premix gas burner in accordance with fig. 1, fuel gas is mixed with air or oxygen or another oxidiser gas to form a premix gas. This premixing takes place upstream of an operational burner deck area of the premix gas burner, adjacent to which operational burner deck area combustion of the premix gas takes place. The fuel gas is for example natural gas, methane or hydrogen, or a mixture of any of these.

Fig. 2 shows, schematically, a first example of a burner deck unit 10 for a premix gas burner 1 according to the first aspect of the invention. In the example of fig. 2, the burner deck unit comprises a flame support 11. The flame support 11 comprises an operational burner deck area 12. In the example of fig. 2, the flame support 11 is made of a metal plate, e.g. a flat metal plate.

The operational burner deck area 12 comprises gas outflow openings. During use of the premix gas burner 1, premix gas is combusted adjacent to the operational burner deck area 12 after the premix gas has flown through the gas outflow openings of the operational burner deck area 12. The operational burner deck area 12 comprises multiple gas outflow openings which are usually arranged in a pattern. The pattern is for example formed by holes and/or slots which extend through a metal plate, wherein the holes form the gas outflow openings.

The burner deck unit further comprises a circumferential edge 13 and a support portion 14. The support portion 14 is present between and the operational burner deck area 12 and a support portion edge 16 which is formed by at least a part of the circumferential edge 13 of the burner deck unit.

The support portion 14 has a support portion thickness and extends in a support portion plane which is perpendicular to the support portion thickness. The support portion 14 is in the example of fig. 2 a rim 15 which extends around the operational burner deck area 12 and which is integral with the flame support 11 , i.e. is formed by a part of the plate that forms the flame support 11. In the example of fig. 2, the circumferential edge 13 of the burner deck unit 10 is entirely formed by the circumferential edge of the flame support 11.

In the example of fig. 2, the support portion does not comprise any holes and/or slots. It is however possible that holes and/or slots are present in the support portion. However, such holes and/or slots in the support portion are not part of the operational burner deck area 12 as in operation no premix gas will flow through such holes and/or slots to be combusted as the arrangement of the support portion in the cavity will prevent flow of premix gas through any holes and/or slots in the support portion.

Fig. 3 shows, schematically, a second example of a burner deck unit 10 for a premix gas burner 1 according to the first aspect of the invention.

In the example of fig. 3, the burner deck unit comprises a flame support 11. The flame support 11 comprises an operational burner deck area 12. In the example of fig. 3, the flame support 11 is made of a woven wire mesh.

The operational burner deck area 12 comprises gas outflow openings. During use of the premix gas burner 1, premix gas is combusted adjacent to the operational burner deck area 12 after the premix gas has flown through the gas outflow openings of the operational burner deck area 12. The woven wire mesh comprises a plurality of metal mesh wires, and gas outflow openings are formed by adjacent metal mesh wires. In the example of fig. 3, the woven wire mesh is made out of metal weft wires and metal warp wires. The burner deck unit further comprises a circumferential edge 13 and a support portion 14. The support portion 14 is present between and the operational burner deck area 12 and a support portion edge 16 which is formed by at least a part of the circumferential edge 13 of the burner deck unit.

In the example of fig. 3, the support portion 14 is formed by a rim 15, which is connected to the woven wire mesh of the flame support 11. The rim 15 is for example formed by metal plates which for example welded or clamped onto the woven wire mesh. In the example of fig. 3, the circumferential edge 13 of the burner deck unit 10 is formed by the circumferential edge of the rim 15 which forms the support portion 14.

The support portion 14 has a support portion thickness and extends in a support portion plane which is perpendicular to the support portion thickness.

In a variant of the embodiment of fig. 3, no rim is added to the flame support 12, and the support portion is formed by the woven wire mesh. In that case, the openings between adjacent wires in the woven wire mesh in the support portion are not part of the operational burner deck area 12 as in operation no premix gas will flow through such openings to be combusted as the arrangement of the support portion in the cavity will prevent flow of premix gas through any holes and/or slots in the support portion.

Fig. 4 shows, schematically, a first embodiment of the premix gas burner according to the first aspect of the invention, shown in part and in cross section.

The premix gas burner in the embodiment of fig. 4 comprises a non-cylindrical burner deck unit 10 and a metal frame 20. In this embodiment, for example any one of the burner deck units 10 in accordance with fig. 2 or fig. 3 (including the described variant of the embodiment of fig. 3) may be used.

The metal frame 20 is adapted to hold the non-cylindrical burner deck unit 10. The metal frame 20 is for example formed by one or more metal plates, e.g. at least one curved metal plate. In the embodiment of fig. 4, the metal frame 20 further comprises a mounting plate 21 which is adapted to mount the premix gas burner in an appliance, such as a heating appliance, such as a building heater system or a hot tap water system.

In the embodiment of fig. 4, the premix gas burner further comprises a cavity in which at least a part of the support portion 14 of the burner deck unit 10 is arranged. The cavity comprises a cavity opening 26 and a cavity inner wall. The cavity inner wall comprises a cavity end wall portion 25, a first cavity wall portion 22 and a second cavity wall portion 23. The at least part of the support portion 14 of the burner deck unit 10 extends through the cavity opening 26 into the cavity. The cavity end wall portion 25 is located opposite to the cavity opening 26. The second cavity wall portion 23 is arranged opposite to the first cavity wall portion 22. The first cavity wall portion 22 and the second cavity wall portion 23 extend parallel to or at a non-perpendicular angle to the support portion plane, and the cavity end wall portion 25 extends between the first cavity wall portion 22 and the second cavity wall portion 23.

The first cavity wall portion 22 is formed by a cavity delimiting area of the metal frame 20.

In the embodiment of fig. 4, the distance between the first cavity wall portion 22 and the second cavity wall portion 23 is larger than the support portion thickness. A clearance 24 is present between the at least part of the support portion 14 which is arranged in the cavity and at least one of the first cavity wall portion 22 and the second cavity wall portion 23.

In the embodiment of fig. 4, - when measured with the frame and the burner deck unit both being at ambient temperature - the support portion 14 extends between the first and the second cavity wall portion 22, 23 over a length which is at least half of the expected thermal contraction of the burner deck unit 10 in the support portion plane when cooling the burner deck unit from maximum operational temperature to ambient temperature. In addition, - again when measured with the frame and the burner deck unit both being at ambient temperature - the cavity end wall portion 25 is spaced apart from the support portion edge 16 by a distance that is at least half of the expected thermal expansion of the burner deck unit 10 in the support portion plane when heating the burner deck unit 10 from ambient temperature to maximum operational temperature.

In the embodiment of fig. 4, the cavity is defined by the cavity delimiting area of the frame 20, a counter plate 32 opposite to the cavity delimiting area of the frame and a spacer 31 which is arranged between the cavity delimiting surface of the frame and the counter plate 32. In this embodiment, the counter plate 32 defines the second cavity wall portion 23, and the spacer 31 defines the distance between the first cavity wall portion 22 and the second cavity wall portion 23.

In this embodiment, one side of the spacer 31 defines the end cavity wall portion 25.

Optionally, the counter plate 32 is connected to the metal frame 20, e.g. by a weld (e.g. one or more spotwelds), or by rivets or bolts.

Optionally, the spacer 31 is connected to the metal frame 20, e.g. by a weld (e.g. one or more spotwelds), or by one or more rivets.

Optionally, the counter plate 32 is connected to the spacer 31 , and the spacer 31 is in turn connected to the metal frame 20.

In the embodiment of fig. 4, the counter plate 32 and the spacer 31 are made of individual parts. Optionally, the counter plate 32 and/or the spacer 31 are made of metal, e.g. steel, stainless steel or aluminium. Alternatively, the counter plate 32 and/or the spacer 31 are made of a resin, e.g. a fibre reinforced resin.

In the embodiment of fig. 4, the flame support has an inner face 17 opposite to the operational burner deck area and the premix gas burner further comprises a gas distributor plate 30, which gas distributor plate 30 is arranged adjacent to and spaced apart from the inner face 17 of the flame support.

In the embodiment of fig. 4, the gas distributor plate 30 is mounted to the counter plate 32.

Fig. 5 shows, schematically, a second embodiment of the premix gas burner according to the first aspect of the invention, shown in part and in cross section.

The premix gas burner in the embodiment of fig. 5 comprises a non-cylindrical burner deck unit 10 and a metal frame 20. In this embodiment, for example any one of the burner deck units 10 in accordance with fig. 2 or fig. 3 (including the described variant of the embodiment of fig. 3) may be used.

The metal frame 20 is adapted to hold the non-cylindrical burner deck unit 10. The metal frame 20 is for example formed by one or more metal plates, e.g. at least one curved metal plate. In the embodiment of fig. 5, the metal frame 20 further comprises a mounting plate 21 which is adapted to mount the premix gas burner in an appliance, such as a heating appliance, such as a building heater system or a hot tap water system.

In the embodiment of fig. 5, the premix gas burner further comprises a cavity in which at least a part of the support portion 14 of the burner deck unit 10 is arranged. The cavity comprises a cavity opening 26 and a cavity inner wall. The cavity inner wall comprises a cavity end wall portion 25, a first cavity wall portion 22 and a second cavity wall portion 23. The at least part of the support portion 14 of the burner deck unit 10 extends through the cavity opening 26 into the cavity. The cavity end wall portion 25 is located opposite to the cavity opening 26. The second cavity wall portion 23 is arranged opposite to the first cavity wall portion 22. The first cavity wall portion 22 and the second cavity wall portion 23 extend parallel to or at a non-perpendicular angle to the support portion plane, and the cavity end wall portion 25 extends between the first cavity wall portion 22 and the second cavity wall portion 23.

The first cavity wall portion 22 is formed by a cavity delimiting area of the metal frame

20. In the embodiment of fig. 5, the distance between the first cavity wall portion 22 and the second cavity wall portion 23 is larger than the support portion thickness. A clearance 24 is present between the at least part of the support portion 14 which is arranged in the cavity and at least one of the first cavity wall portion 22 and the second cavity wall portion 23.

In the embodiment of fig. 5, - when measured with the frame and the burner deck unit both being at ambient temperature - the support portion 14 extends between the first and the second cavity wall portion 22, 23 over a length which is at least half of the expected thermal contraction of the burner deck unit 10 in the support portion plane when cooling the burner deck unit from maximum operational temperature to ambient temperature. In addition, - again when measured with the frame and the burner deck unit both being at ambient temperature - the cavity end wall portion 25 is spaced apart from the support portion edge 16 by a distance that is at least half of the expected thermal expansion of the burner deck unit 10 in the support portion plane when heating the burner deck unit 10 from ambient temperature to maximum operational temperature.

In the embodiment of fig. 5, the cavity is defined by the metal frame 20 on two sides of the cavity. In addition, a counter plate 32 opposite to the first cavity wall portion 22 is provided. In this embodiment, the counter plate 32 defines the second cavity wall portion 23, and an end wall portion 27 of the frame 20 defines the distance between the first cavity wall portion 22 and the second cavity wall portion 23.

In this embodiment, the end wall portion 27 of the frame 20 forms an end cavity wall portion 25.

Optionally, the counter plate 32 is connected to the metal frame 20, e.g. by a weld (e.g. one or more spotwelds), or by rivets.

Optionally, the counter plate 32 is made of metal, e.g. steel, stainless steel or aluminium. Alternatively, the counter plate 32 is made of a resin, e.g. a fibre reinforced resin.

In the embodiment of fig. 5, the flame support has an inner face 17 opposite to the operational burner deck area and the premix gas burner further comprises a gas distributor plate 30, which gas distributor plate 30 is arranged adjacent to and spaced apart from the inner face 17 of the flame support.

In the embodiment of fig. 5, the gas distributor plate 30 is mounted to the counter plate 32.

Fig. 6 shows, schematically, a third embodiment of the premix gas burner according to the first aspect of the invention, shown in part and in cross section. The premix gas burner in the embodiment of fig. 6 comprises a non-cylindrical burner deck unit 10 and a metal frame 20. In this embodiment, for example any one of the burner deck units 10 in accordance with fig. 2 or fig. 3 (including the described variant of the embodiment of fig. 3) may be used.

The metal frame 20 is adapted to hold the non-cylindrical burner deck unit 10. The metal frame 20 is for example formed by one or more metal plates, e.g. at least one curved metal plate. In the embodiment of fig. 6, the metal frame 20 further comprises a mounting plate 21 which is adapted to mount the premix gas burner in an appliance, such as a heating appliance, such as a building heater system or a hot tap water system.

In the embodiment of fig. 6, the premix gas burner further comprises a cavity in which at least a part of the support portion 14 of the burner deck unit 10 is arranged. The cavity comprises a cavity opening 26 and a cavity inner wall. The cavity inner wall comprises a cavity end wall portion 25, a first cavity wall portion 22 and a second cavity wall portion 23. The at least part of the support portion 14 of the burner deck unit 10 extends through the cavity opening 26 into the cavity. The cavity end wall portion 25 is located opposite to the cavity opening 26. The second cavity wall portion 23 is arranged opposite to the first cavity wall portion 22. The first cavity wall portion 22 and the second cavity wall portion 23 extend parallel to or at a non-perpendicular angle to the support portion plane, and the cavity end wall portion 25 extends between the first cavity wall portion 22 and the second cavity wall portion 23.

The first cavity wall portion 22 is formed by a cavity delimiting area of the metal frame 20.

In the embodiment of fig. 6, the distance between the first cavity wall portion 22 and the second cavity wall portion 23 is larger than the support portion thickness. A clearance 24 is present between the at least part of the support portion 14 which is arranged in the cavity and at least one of the first cavity wall portion 22 and the second cavity wall portion 23.

In the embodiment of fig. 6, - when measured with the frame and the burner deck unit both being at ambient temperature - the support portion 14 extends between the first and the second cavity wall portion 22, 23 over a length which is at least half of the expected thermal contraction of the burner deck unit 10 in the support portion plane when cooling the burner deck unit from maximum operational temperature to ambient temperature. In addition, - again when measured with the frame and the burner deck unit both being at ambient temperature - the cavity end wall portion 25 is spaced apart from the support portion edge 16 by a distance that is at least half of the expected thermal expansion of the burner deck unit 10 in the support portion plane when heating the burner deck unit 10 from ambient temperature to maximum operational temperature.

In the embodiment of fig. 6, the flame support has an inner face 17 opposite to the operational burner deck area and the premix gas burner further comprises a gas distributor plate 30, which gas distributor plate 30 is arranged adjacent to and spaced apart from the inner face 17 of the flame support.

In the embodiment of fig. 6, the cavity is defined by the metal frame 20 on two sides of the cavity. In this embodiment, the gas distributor plate defines the second cavity wall portion 23, and an end wall portion 27 of the frame 20 defines the distance between the first cavity wall portion 22 and the second cavity wall portion 23.

In this embodiment, the end wall portion 27 of the frame 20 forms the end cavity wall portion 25.

Optionally, the gas distributor plate 30 is connected to the metal frame 20, e.g. by a weld (e.g. one or more spotwelds), or by rivets and/or bolts.

Fig. 7 shows, schematically, a fourth embodiment of the premix gas burner according to the first aspect of the invention, shown in part and in cross section.

The premix gas burner in the embodiment of fig. 7 comprises a non-cylindrical burner deck unit 10 and a metal frame 20. In this embodiment, for example any one of the burner deck units 10 in accordance with fig. 2 or fig. 3 (including the described variant of the embodiment of fig. 3) may be used.

The metal frame 20 is adapted to hold the non-cylindrical burner deck unit 10. The metal frame 20 is for example formed by one or more metal plates, e.g. at least one curved metal plate. In the embodiment of fig. 7, the metal frame 20 further comprises a mounting plate 21 which is adapted to mount the premix gas burner in an appliance, such as a heating appliance, such as a building heater system or a hot tap water system.

In the embodiment of fig. 7, the premix gas burner further comprises a cavity in which at least a part of the support portion 14 of the burner deck unit 10 is arranged. The cavity comprises a cavity opening 26 and a cavity inner wall. The cavity inner wall comprises a cavity end wall portion 25, a first cavity wall portion 22 and a second cavity wall portion 23. The at least part of the support portion 14 of the burner deck unit 10 extends through the cavity opening 26 into the cavity. The cavity end wall portion 25 is located opposite to the cavity opening 26. The second cavity wall portion 23 is arranged opposite to the first cavity wall portion 22. The first cavity wall portion 22 and the second cavity wall portion 23 extend parallel to or at a non-perpendicular angle to the support portion plane, and the cavity end wall portion 25 extends between the first cavity wall portion 22 and the second cavity wall portion 23.

The first cavity wall portion 22 is formed by a cavity delimiting area of the metal frame 20.

In the embodiment of fig. 7, the distance between the first cavity wall portion 22 and the second cavity wall portion 23 is larger than the support portion thickness. A clearance 24 is present between the at least part of the support portion 14 which is arranged in the cavity and at least one of the first cavity wall portion 22 and the second cavity wall portion 23.

In the embodiment of fig. 7, - when measured with the frame and the burner deck unit both being at ambient temperature - the support portion 14 extends between the first and the second cavity wall portion 22, 23 over a length which is at least half of the expected thermal contraction of the burner deck unit 10 in the support portion plane when cooling the burner deck unit from maximum operational temperature to ambient temperature. In addition, - again when measured with the frame and the burner deck unit both being at ambient temperature - the cavity end wall portion 25 is spaced apart from the support portion edge 16 by a distance that is at least half of the expected thermal expansion of the burner deck unit 10 in the support portion plane when heating the burner deck unit 10 from ambient temperature to maximum operational temperature.

In the embodiment of fig. 7, the flame support has an inner face 17 opposite to the operational burner deck area and the premix gas burner further comprises a gas distributor plate 30, which gas distributor plate 30 is arranged adjacent to and spaced apart from the inner face 17 of the flame support.

In the embodiment of fig. 7, the cavity is defined by the metal frame 20 on one side of the cavity. In this embodiment, the gas distributor plate defines the second cavity wall portion 23. In addition, the gas distributor plate 30 has an end wall portion 33 which defines the distance between the first cavity wall portion 22 and the second cavity wall portion 23.

In this embodiment, the end wall portion 33 of the gas distributor plate 30 forms the end cavity wall portion 25.

Optionally, the gas distributor plate 30 is connected to the metal frame 20, e.g. by a weld (e.g. one or more spotwelds), or by rivets and/or bolts. Fig. 8 shows an example of a metal plate 100 which can be used in the method according to the first aspect of the invention and in the method according to the second aspect of the invention.

In the method according to the first aspect of the and in the method according to the second aspect of the invention, a premix gas burner is manufactured, in which manufacturing process a metal plate is folded in order to create a cavity in which a support portion of a burner deck unit or another element of a premix gas burner can be accommodated with a clearance.

Fig. 8 shows an example of a metal plate 100 which can used in these methods.

The metal plate 100 has a first part 101 which in the method will form a primary portion, and a second part which in the method will form a secondary portion 102. The first part 101 and the second part 102 are separated from each other by a primary fold line 111. The primary fold line 111 optionally is scored, but this is not necessary.

The metal plate 100 has a plate thickness and comprises at least one tab 105 on a first side of the metal plate 100. The tab 105 extends from a tab base 106 to a tab top 107. The tab base 106 is located at a distance from the primary fold line 111 , which distance is larger than twice the plate thickness plus the support portion thickness or the thickness of a premix gas burner element which is to be supported by the metal plate. The tab top 107 is further away from the primary fold line 111 than the tab base 106. In the example of fig. 8, the metal plate 100 comprises multiple tabs 105.

The metal plate 100 further comprises a second fold line 112, which is located at the tab base 106. The secondary fold line 112 optionally is scored, but this is not necessary.

In the embodiment of fig. 8, the primary fold line 111 and secondary fold line 112 each are a straight line.

Fig. 9a and Fig. 9b show steps in an embodiment of the first variant of the method according to the first aspect of the invention and/or the first variant of the method according to the second aspect of the invention.

As is shown in fig. 9a, in this embodiment, first the metal plate 100 of fig. 8 is folded over the primary fold line 111. By this folding, a primary portion 121 of the metal plate is created which is arranged at an angle relative to a secondary portion 122 of the metal plate. The primary portion is arranged on a first side of the primary fold line 111 and the secondary portion is arranged at a second side of the primary fold line 111. The first side and the second side are opposite to each other, The secondary portion 122 comprises the tab 105.

Then, in this embodiment, at least a part of the support portion 14 of the burner deck unit (first aspect of the invention) or a premix gas burner element 114 which is to be supported by the metal plate (second aspect of the invention) is arranged onto or adjacent to the primary portion 121 of the metal plate.

Then, in this embodiment, the secondary portion 122 of the metal plate 100 is folded over the secondary fold line 112 by using a punch with a predetermined stroke length. The tab 105 comes to extend over at least a part of the support portion of the burner deck unit 14 (first aspect of the invention) a premix gas burner element 114 which is to be supported by the metal plate (second aspect of the invention). The tab 105 also becomes arranged at an angle relative to the part 108 of the secondary portion of the metal plate that is located between the primary fold line 111 and the secondary fold line 112.

This way, in the method according to the first aspect of the invention, at least a part of the cavity inner wall of the cavity of the premix burner according to the first aspect of the invention is created, with the primary portion 121 of the metal plate defining one of the first cavity wall portion or the second cavity wall portion, the tabs 105 defining the other one of the first cavity wall portion or the second cavity wall portion, and the part 108 of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining the cavity end wall portion.

Likewise, in the method according to the second aspect of the invention, this way at least a part of a cavity inner wall of a cavity of a premix burner in which cavity the premix gas burner element is to be arranged is created, with the primary portion 121 of the metal plate defining one of a first cavity wall portion or a second cavity wall portion, the tabs 105 defining the other one of the first cavity wall portion or the second cavity wall portion, and the part 108 of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining a cavity end wall portion.

In the embodiment of fig. 9a and fig. 9b, the metal plate 100 is folded over the primary fold line 111 such that after this folding, the angle between the primary portion 121 of the metal plate and the secondary portion 122 of the metal plate is between 80° and 100°, optionally 90°.

In the embodiment of fig. 9a and fig. 9b, the secondary portion 122 of the metal plate is folded over the secondary fold line 112 such that after this folding, the angle between tab 105 and the part 108 of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line is between 80° and 100°, optionally 90°.

In the embodiment of fig. 9a and fig. 9b, the metal plate 100 is folded over the primary fold line 111 and the secondary portion of the metal plate is folded over the secondary fold line 112 such that after this folding, the tab 105 and the primary portion 101 of the metal plate 100 extend parallel to each other or at an angle of 30° or less.

Fig. 10a and Fig. 10b show steps in an embodiment of the second variant of the method according to the first aspect of the invention and/or the second variant of the method according to the second aspect of the invention.

As is shown in fig. 10a, in this embodiment, first the metal plate 100 of fig. 8 is folded over the primary fold line 111. By this folding, a primary portion 121 of the metal plate is created which is arranged at an angle relative to a secondary portion 122 of the metal plate. The primary portion is arranged on a first side of the primary fold line 111 and the secondary portion is arranged at a second side of the primary fold line 111. The first side and the second side are opposite to each other, The secondary portion 122 comprises the tab 105.

Then, in this embodiment, at least a part of the support portion 14 of the burner deck unit (first aspect of the invention) or a premix gas burner element 114 which is to be supported by the metal plate (second aspect of the invention) is arranged onto or adjacent to the primary portion 121 of the metal plate.

Then, in this embodiment, the secondary portion 122 of the metal plate 100 is folded over the secondary fold line 112 by using a punch with a predetermined stroke length.

The tabs 105 come to extend parallel to but not overlapping with the at least a part of the support portion 14 (first aspect of the invention) a premix gas burner element 114 which is to be supported by the metal plate (second aspect of the invention). The tabs 105 become arranged at an angle relative to the part 108 of the secondary portion of the metal plate that is located between the primary fold line 111 and the secondary fold line 112.

This way, in the method according to the first aspect of the invention, at least a part of the cavity inner wall of the cavity of the premix burner according to the first aspect of the invention is created, with the primary portion 121 of the metal plate defining the first cavity wall portion or the second cavity wall portion and the part 108 of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining the cavity end wall portion. Likewise, in the method according to the second aspect of the invention, at least a part of the cavity inner wall of the cavity of a premix burner in which cavity the premix gas burner element is to be arranged is created, with a primary portion 121 of the metal plate defining the first cavity wall portion or a second cavity wall portion and the part 108 of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining a cavity end wall portion.

In the embodiment of fig. 10a and fig. 10b, the metal plate 100 is folded over the primary fold line 111 such that after this folding, the angle between the primary portion 121 of the metal plate and the secondary portion 122 of the metal plate is between 80° and 100°, optionally 90°.

In the embodiment of fig. 10a and fig. 10b, the secondary portion 122 of the metal plate is folded over the secondary fold line 112 such that after this folding, the angle between tab 105 and the part 108 of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line is between 80° and 100°, optionally 90°.

In the embodiment of fig. 10a and fig. 10b, the metal plate 100 is folded over the primary fold line 111 and the secondary portion of the metal plate is folded over the secondary fold line 112 such that after this folding, the tab 105 and the primary portion 101 of the metal plate 100 extend parallel to each other or at an angle of 30° or less.

Fig. 11a and Fig. 11b show steps in an embodiment of the third variant of the method according to the first aspect of the invention and/or the third variant of the method according to the second aspect of the invention.

As is shown in fig. 11a, in this embodiment, first the metal plate 100 of fig. 8 is folded over the primary fold line 111. By this folding, a primary portion 121 of the metal plate is created which is arranged at an angle relative to a secondary portion 122 of the metal plate. The primary portion is arranged on a first side of the primary fold line 111 and the secondary portion is arranged at a second side of the primary fold line 111. The first side and the second side are opposite to each other, The secondary portion 122 comprises the tab 105.

Then, in this embodiment, at least a part of the support portion 14 of the burner deck unit (first aspect of the invention) or a premix gas burner element 114 which is to be supported by the metal plate (second aspect of the invention) adjacent to and/or onto the tabs of the metal plate, not extending past the bases of the tabs. Then, in this embodiment, the secondary portion 122 of the metal plate 100 is folded over the secondary fold line 112 by using a punch with a predetermined stroke length.

The tabs 105 come to extend come to extend over at least a part of the support portion 14 (first aspect of the invention) a premix gas burner element 114 which is to be supported by the metal plate (second aspect of the invention). The tabs 105 become arranged at an angle relative to the part 108 of the secondary portion of the metal plate that is located between the primary fold line 111 and the secondary fold line 112.

This way, in the method according to the first aspect of the invention, at least a part of the cavity inner wall of the cavity of the premix burner according to the first aspect of the invention between the primary portion of the metal plate and the tab of the metal plate is created, with the tabs 105 of the metal plate defining the first cavity wall portion or the second cavity wall portion and the part 108 of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining the cavity end wall portion.

Likewise, in the method according to the second aspect of the invention, at least a part of the cavity inner wall of the of a premix burner in which cavity the premix gas burner element is to be arranged between the primary portion 121 of the metal plate and the tabs 105 of the metal plate is created, with the tabs of the metal plate defining a first cavity wall portion or a second cavity wall portion and the part 108 of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line defining a cavity end wall portion.

In the embodiment of fig. 11a and fig. 11b, the metal plate 100 is folded over the primary fold line 111 such that after this folding, the angle between the primary portion 121 of the metal plate and the secondary portion 122 of the metal plate is between 80° and 100°, optionally 90°.

In the embodiment of fig. 11a and fig. 11b, the secondary portion 122 of the metal plate is folded over the secondary fold line 112 such that after this folding, the angle between tab 105 and the part 108 of the secondary portion of the metal plate that is located between the primary fold line and the secondary fold line is between 80° and 100°, optionally 90°.

In the embodiment of fig. 11a and fig. 11b, the metal plate 100 is folded over the primary fold line 111 and the secondary portion of the metal plate is folded over the secondary fold line 112 such that after this folding, the tab 105 and the primary portion 101 of the metal plate 100 extend parallel to each other or at an angle of 30° or less.