A gas HOB with an improved heat shield

Abstract

The invention relates to a gas hob comprising a top plate (10) made of tempered glass or ceramic glass; a pan support (20) arranged on the upper part (12) of the top plate (10), and at least one gas burner (40) having a heat shield (30). The hob comprises a depression (34) arranged in the heat shield (30) to form an air inlet port (a) directing ambient air towards an air inlet opening (44) at the lower part (42) of the burner (40).

Description

[0001] A GAS HOB WITH AN IMPROVED HEAT SHIELD

[0002] TECHNICAL FIELD

[0003] The invention relates to a gas hob having a heat shield positioned on a glass or glassceramic top plate.

[0004] PRIOR ART

[0005] A gas hob comprises a top plate and a burner removably mounted on a corresponding through-opening on the top plate. A pan support (grate) with a flat or voluminous finger structure, fixed to a frame on the top plate, is placed surrounding the burner. The burner heats a cooking vessel supported by its base with corresponding fingers by generating an upward flame. In a gas hob where the top plate is made of a metal sheet, the heating of the top plate by the flame does not pose any problem as it has high thermal resistance. However, the thermal resistance of a top plate made of tempered glass or glass-ceramic is relatively lower. Therefore, a heat shield, which prevents the flame from the burner from heating the top plate, is placed aligned under the burner on the glass top plate to form a thermal barrier. The heat shield is generally made of a metal plate.

[0006] EP2564121 discloses a gas hob with a square heat shield. A gas hob having a top plate made of tempered glass or glass-ceramics comprises at least one gas burner placed on the top plate, a heat shield, and a pan support. The pan support has a frame that can be compatibly placed on the heat shield, while the heat shield is designed as a polygonal flat disc, specifically rectangular, for the thermal protection of the top plate.

[0007] BRIEF DESCRIPTION OF THE INVENTION

[0008] The object of the invention is to reduce thermal stresses that may occur on the glass or glass-ceramic top plate with an improved heat shield, while simultaneously maintaining high combustion efficiency.

[0009] In order to achieve the above objective, the invention is a gas hob comprising a top plate made of tempered glass or ceramic glass; a pan support arranged on the upper part of the top plate, and at least one gas burner having a heat shield. In the gas hob, the heat shield comprises a depression arranged to form an air inlet port directing ambient air towards an air inlet opening at the lower part of the burner. The heat shield, on the one hand, reduces the thermal stresses of the top plate by forming a thermal barrier protecting the upper part of the top plate against the heat generated due to the flame emanating from the gas burner located on its upper part in a cooking situation, and on the other hand, increases the combustion efficiency by forming an air inlet port with the depression that directs ambient air to the air inlet opening of the gas burner. In a possible configuration, the form of the depression may be flat or patterned. It is evident that the depression may have a truncated cone structure towards the radial centre or a prismatic or conical structure with softened corners. It is also possible for functional elements, for example, holes or functional protrusions, to be present on the depression.

[0010] In a preferred embodiment of the invention, the depression is configured to descend towards the radial centre of the burner and is particularly arranged in a circular, elliptical, or oval form. In this way, the air inlet port supplies ambient air along a circumferential line around the burner. The circumferential air inlet port allows it to continue functioning even if it is partially blocked for any reason.

[0011] In a preferred embodiment of the invention, the air inlet port provided by the depression is arranged equidistant from the heat shield along the periphery of the burner. In this case, the profile of the air transferred to the burner is not distorted, and the formation of turbulence causing noise is prevented.

[0012] In a preferred embodiment of the invention, the depression comprises a short inclined portion descending radially inwards from the outer periphery of the heat shield and, as a continuation thereof, a long planar portion relative to the inclined portion parallel to the top plate. In this way, it is possible to produce it monolithically by forming it from a simple plate according to the calculated optimum radial width of the air inlet port.

[0013] In a preferred embodiment of the invention, the heat shield is in the form of a bent monolithic flat metal plate. In this way, the heat shield can be obtained simply and economically. Furthermore, an effective heat shield against thermal stresses is provided. Additionally, precise sizing of the air inlet port is possible.

[0014] In a preferred embodiment of the invention, the heat shield is square in form. It has been determined that the square form provides better dimensional stability when the depression is applied, compared to other geometric forms. Thereby, it has been possible to obtain a laminar air profile that reduces noise at the ambient air inlet.

[0015] A preferred embodiment of the invention comprises a hole arranged in the middle of the heat shield through which the burner is placed. The hole allows the burner to be easily mounted from above the top plate such that it provides gas communication to the gas distribution assembly located beneath the top plate. In a preferred embodiment of the invention, the pan support comprises at least three spaced fingers facing each other and a frame arranged adjacent to the outer periphery of the heat shield. In this way, the heat shield prevents the pan support from being displaced by abutting against the frame.

[0016] A preferred embodiment of the invention comprises a plurality of gas burners, each having its own heat shield, and each burner having an adjacent pan support. In this way, a gas hob with compact cooking zones is obtained.

[0017] A preferred embodiment of the invention comprises a wok burner, and the ratio of the radial distance of the air inlet port to the depth of the depression is between four to one and one to one. It has been determined that the specified ratio surprisingly creates a region where there is no increase in noise while providing an increase in efficiency by supplying the high flow rate of ambient air required for the wok burner to the wok burner through the air inlet port.

[0018] In a preferred embodiment of the invention, it comprises a flange-like skirt provided on the outer periphery of the heat shield and seated on the upper part of the top plate from its outer edge. Thanks to the skirt, the thermal stresses generated by the burner are effectively dissipated from the heat shield without creating an obstacle on the top plate.

[0019] BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a top view of a representative embodiment of a gas hob with an improved heat shield according to the invention, comprising a bar-type pan support.

[0021] Figure 2a is a cross-sectional view of the cooking unit comprising a medium or small gas burner of the gas hob shown in Figure 1.

[0022] Figure 2b is a cross-sectional view of the cooking unit comprising a wok gas burner of the gas hob shown in Figure 1 .

[0023] Figure 3 is a top view of a representative embodiment of a gas hob with an improved heat shield according to the invention, comprising a cast pan support.

[0024] Figure 4a is a cross-sectional view of the cooking unit comprising a medium or small gas burner of the gas hob shown in Figure 3.

[0025] Figure 4b is a cross-sectional view of the cooking unit comprising a wok gas burner of the gas hob shown in Figure 3.

[0026] DETAILED DESCRIPTION OF THE INVENTION

[0027] In this detailed description, the development subject to the invention is described with references to examples, without any limitation, and only to better explain the subject. In Figure 1 , a household hob is shown from above, having a total of four burners (30, 40), one being a 4.2 kW wok burner (50) and the others being three medium and small type burners (40) of 2 kW (semi-rapid) and 1 kW (auxiliary). The gas flow rate of each corresponding burner (40, 50) is adjusted by a plurality of control knobs (1 ) arranged in a row near the edge on an upper part (12) of a flat and planar ceramic top plate (10). The wok burner (50) is described in the patent publication EP3980687, incorporated herein by reference. The other medium and small burners (40) are described in EP3980690, also incorporated herein by reference.

[0028] A heat shield (30), which is a monolithic metal plate bent in the form of a square bowl with its mouth facing downwards, is seated on the upper part (12) of the top plate (10), centred on each corresponding burner (40, 50). A depression (34) is formed on the upper part of the heat shield (30), descending towards the upper part (12) of the top plate (10). In other words, the depression (34) is at the top surface of the bowl form. The depression (34) starts equidistantly from the outer periphery of the heat shield (30) and continues at its lower part to circumferentially surround the air inlet port (a). The air inlet port (a) for the wok burner (50) is arranged with a larger diameter compared to the air inlet port (a) for the other medium and small burners (30). A frame (21) surrounding the outer periphery of the heat shield (30) is obtained by bending an l-shaped metal and, together with L-shaped bar-type fingers (22) placed opposite each other on it, forms a pan support (20). The fingers (22) are fixed to the frame (21) by a weld seam from one end of each upright L-form, thereby creating a support base that will support a pan from below along their long edges. The fingers (22) are provided as two opposing pairs rising from the upper edge of the frame (21) corresponding to each burner (40, 50), with their free ends facing each other. Thus, four plus-like perpendicular extensions are obtained on the square-shaped frame (21 ) adjacent to the heat shield (30) with the fingers (22).

[0029] In Figures 2a and 2b, cooking zones, one with a medium-sized burner (40) and one with a wok burner (50) respectively, are shown in cross-section. Both burners (40, 50) are aligned over a corresponding hole (14) on the top plate (10). Bar-shaped fingers (22) are used in the pan support (20) seated on the upper part (12) of the top plate (10). The rising extension of the finger (22) is wide, and the extension extending towards the burner (40, 50) is narrow. The upper edge of the frame (21 ) is fixed into a recess located at the inner corner of the rising extension of the finger (22). A silicone gasket (not shown) is mounted on the lower edge of the frame (21 ), and the frame (21) is seated on the upper part (12) of the top plate (10) via the gasket. The inwardly facing edge of the frame (21 ) is adjacent to the outer periphery of the heat shield (30). Thus, when the frame (21) is placed circumferentially on the heat shield (30), its movement on the top plate (10) will cause it to contact the outer periphery of the heat shield (30), thereby preventing the pan support (20) from being displaced on the top plate (10). The heat shield (30) is placed on the top plate (10) with a skirt (32) profile forming its mouth portion at its outer periphery. The skirt (32) is obtained by outwardly widening the vertically extending outer periphery with a flange-like structure.

[0030] A hole (38) is provided in the middle of the heat shield (30). The neck portion of the burner (40, 50), which accesses the gas connection within the gas hob, passes through the hole (38). The air inlet opening (44) of the burner (40, 50) is at the lower part (42) of the burner (40, 50) head, and the air inlet port (a) in the portion remaining between the inner boundary of the depression (34) and the air inlet opening (44) allows the passage of ambient air by directing it radially inwards towards the burner (40, 50). The depression (34) form of the burner (40) shown in Figure 2a is radially narrower and shallower compared to the depression (34) form created for the wok burner (50) shown in Figure 2b. The depression (34) rises with an inclination of 5 degrees relative to the planar portion (36). In Figure 2a, an inclined portion is formed after the radial portion distanced from the outer periphery of the depression (34) to obtain the depth of the depression (34), and following this, a planar portion (36) extends up to the hole (38). In this way, an inclined channel is obtained radially outward and inward of the portion of the burner (40) radially aligned with the heat shield (30), and the channel forms the circumferential air inlet port (a) at the part corresponding to the lower part (42) of the burner (40) and continues up to the hole (38), assisting the passage of air from the lower part (42) to the burner (40). The neck portion of the burner (40) passing through the hole (38) pushes the air directed from the air inlet port (a) upwards towards the air inlet opening (44) of the burner (40). For this, the diameter of the hole (38) is set equal to the diameter of the neck of the burner (40) passing through the hole (38).

[0031] In Figure 2b, the radial distance (r) between the outer periphery of the wok burner (50) head part and the outer edge of the depression (34) is set wider compared to other burners (40). Thus, the volume of air to be directed over the depression (34) is increased. The depression depth (h), which is the distance between the upper edge of the depression (34) and the planar portion (36), is also greater compared to the other burner (40). Here, the ratio of the radial distance (r) to the depression depth (h) is set as 2:1. It has been observed that at the selected ratio, even when the wok burner (50) operates at full power, the air drawn by the wok burner (50) creates a laminar flow, and no additional noise is generated compared to other hob burners without a heat shield (30). The depression (34) rises with an inclination of 30 degrees relative to the planar portion (36). When the wok burner (50) is operated via the control knob (1), a flame is formed radially outwards from the flame crown of the wok burner (50), and the wok burner (50) creates suction from its lower part (52), forming a vacuum at the air inlet port (a). Ambient air follows the form of the depression (34) and reaches the air inlet opening (54) at the lower part (52) of the wok burner (50) through the air inlet port (a), enriching the air-gas mixture of the wok burner (50) in terms of oxygen. Thus, efficient flame formation is ensured, and combustion efficiency is increased. A similar operating principle applies to the burner (40) in Figure 2a.

[0032] Figure 3 is structurally the same as the hob in Figure 1 , the only difference being that the pan support (20) is cast. The arrangement and operation of all elements are the same as the hob in Figure 1. Here, the frame (21) of the pan support (20) is thick, and the fingers (22) are integral with the frame (21). In Figures 4a and 4b, cross-sections of the cooking zones where a burner (40) and a wok burner (50) shown in Figure 3 are located are presented. The structure in Figure 4a is the same as the structure given in Figure 2a, except that the pan support (20) is cast and integral with the fingers (22). In contrast, the structure given in Figure 4b is also the same as the structure given in Figure 2b, except that the pan support (20) is cast and integral with the fingers (22). The burner (40), with its neck portion passing through the hole (38), is removably fitted to the part (not shown) under the top plate (10) from the opening (14). When the burner (40) generates a flame, ambient air reaches the air inlet port (a) over the depression (34) and is drawn upwards by the vacuum effect of the burner (40) into the air inlet opening (44). Since the planar portion (36) at the lower end of the depression (34) forms a wide angle, pressure loss is kept to a minimum while ambient air is sucked in.

[0033] REFERENCE NUMERALS

[0034] 1 Control knob 36 Planar portion

[0035] 10 Top plate 38 Hole

[0036] 12 Upper part 40 Burner

[0037] 14 Opening 42 Lower part

[0038] 20 Pan support 44 Air inlet opening

[0039] 21 Frame 50 Wok burner

[0040] 22 Finger 52 Lower part

[0041] 30 Heat shield 54 Air inlet opening

[0042] 32 Skirt a Air inlet port

[0043] 34 Depression r Radial distance h Depression depth

Claims

CLAIMS1- A gas hob comprising a top plate (10) made of tempered glass or ceramic glass; a pan support (20) arranged on the upper part (12) of the top plate (10), and at least one gas burner (40) having a heat shield (30), characterized in that the heat shield (30) comprises a depression (34) arranged to form an air inlet port (a) directing ambient air towards an air inlet opening (44) at the lower part (42) of the burner (40).2- A gas hob according to any one of the preceding claims, wherein the depression (34) is configured to descend towards the radial center of the burner (40) and is particularly arranged in a circular, elliptical, or oval form.3- A gas hob according to any one of the preceding claims, wherein the air inlet port (a) provided by the depression (34) is arranged equidistant from the heat shield (30) along the periphery of the burner (40).4- A gas hob according to any one of the preceding claims, wherein the depression (34) comprises a short inclined portion descending radially inwards from the outer periphery of the heat shield (30) and, as a continuation thereof, a long planar portion (36) relative to the inclined portion parallel to the top plate (10).5- A gas hob according to any one of the preceding claims, wherein the heat shield (30) is in the form of a bent monolithic flat metal plate.6- A gas hob according to any one of the preceding claims, wherein the heat shield (30) is square in form.7- A gas hob according to any one of the preceding claims, wherein the heat shield (30) comprises a hole (38) arranged in its center, through which the burner (40) is placed.8- A gas hob according to any one of the preceding claims, wherein the pan support (20) comprises at least three spaced fingers (22) facing each other and a frame (21 ) arranged adjacent to the outer periphery of the heat shield (30).9- A gas hob according to any one of the preceding claims, wherein the hob further comprises a plurality of gas burners (40, 50), each having its own heat shield (30), and each burner (40, 50) having an adjacent pan support (20).10- A gas hob according to any one of the preceding claims, wherein the hob further comprises a wok burner (50) the ratio of the radial distance (r) of the air inlet port (a) to the depth (h) of the depression (34) is between 4:1 and 1 :

1. 11- 11- A gas hob according to any one of the preceding claims, wherein the heat shield(30) comprises a flange-like skirt (32) provided on its outer periphery and seated on the upper part (12) of the top plate (10) from its outer edge.

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