A domestic gas oven with a pizza stone

Abstract

The invention relates to a domestic gas oven comprising a muffle (10) that delimits a cooking chamber by means of opposing side walls (12), an upper wall (18), a rear wall (15), and a bottom frame (14) provided therebetween; and further comprising a lower gas burner (20), equipped with a flame spreader (22), placed beneath the bottom frame (14) on a support sheet (40) fixed to the muffle (10). The oven comprises a baking stone (30) that is arranged such that, when seated on the bottom frame (14) from a support wall (36), the height (h) between it and the flame spreader (22) is adjusted to allow the flames produced by the flame spreader (22) to directly reach a lower portion (34) of the baking stone (30).

Description

[0001] DESCRIPTION

[0002] A DOMESTIC GAS OVEN WITH A PIZZA STONE

[0003] TECHNICAL FIELD

[0004] The present invention relates to a domestic gas oven provided with a gas burner arranged so as to heat a muffle that delimits a cooking chamber.

[0005] STATE OF THE ART

[0006] It is common in domestic ovens to use a gas burner for heating the bottom and top portions of a muffle that defines the cooking chamber. The gas burner is typically fixed under the bottom of the muffle on a supporting sheet metal. With an ignition device, the gas-air mixture coming from the gas burner is ignited, and the desired cooking temperature is obtained by adjusting the gas flow rate.

[0007] In order to heat the bottom of the muffle, flames emerging sequentially from a flame spreader of the lower gas burner extend toward the bottom of the muffle and heat it; in turn, by convection, they heat the cooking chamber. Depending on the type of oven, a blower fan may be provided behind the muffle to ensure circulation of the hot air inside the cooking chamber.

[0008] Rails forming tray supports are mounted on opposing side walls of the muffle. By shaping the side wall itself or by securing wire-form support elements onto a flat side wall, it becomes possible to install removable trays that can be slid in and out of the cooking chamber.

[0009] A ready-to-use baking stone, also known as a pizza stone, is commonly employed in gas ovens for baking items such as bread and pizza, specifically those with a firm dough base. Depending on the user’s need, the baking stone procured is placed inside the muffle, usually on top of a tray or a wire rack. In this way, the baking stone is heated by the circulating cooking air, and then the tray or rack is taken out, the dough to be baked is placed directly onto the baking stone, and the assembly is pushed back into the muffle. However, heating the baking stone in a domestic oven takes a long time due to heat transfer by convection. Even though a blower fan may be used to facilitate circulation, heating the stone still requires significant time during the baking process, thus demanding extra time and energy for preheating. BRIEF DESCRIPTION OF THE INVENTION

[0010] The objective of the present invention is to accelerate baking processes involving a baking stone in a gas oven.

[0011] To achieve this objective, the invention concerns a domestic gas oven comprising a muffle that delimits a cooking chamber by means of opposing side walls, an upper wall, a rear wall, and a bottom frame provided between them and a lower gas burner equipped with a flame spreader, positioned beneath the bottom frame on a support sheet fixed to the muffle.

[0012] The domestic gas oven includes a baking stone that, when seated removably from a support wall onto the bottom frame, is arranged at a height (h) from the flame spreader such that the flames from the flame outlet directly reach a lower portion of the baking stone. Thanks to the direct flame access to the baking stone, the heating time of the baking stone is reduced in the domestic oven, and thus the preheating period is shortened. The baking stone is simply supported from the outer surface of the bottom frame and is sized accordingly. Consequently, once baking is completed, the baking stone can be lifted off the bottom frame, and for a different cooking process, for instance, an enameled cover can be placed onto the bottom frame.

[0013] In a preferred embodiment of the invention, the baking stone is a flat, planar monoblock slab made of ceramic, cordierite, clay, porcelain, natural stone, or metal. In this way, the spot-like heat distribution profile created by flames coming directly from the burner’s flame spreader can be made uniform across the top surface of the slab. It has been found that these selected materials do not crack under thermal shock when used with direct flame cooking, and their capacity to distribute and retain heat allows the dough base to become crispy during baking.

[0014] In a preferred embodiment of the invention, the baking stone includes a narrowed portion that tapers from the support wall to extend at least partially into the bottom frame. By extending into the bottom frame, the narrowed portion brings the baking stone closer to the flame spreader. This arrangement not only helps fix the baking stone on the oven floor during cooking but also, by ensuring proximity to the flame spreader, enables a compact oven construction. Although the narrowed portion may have a single step, in some implementations it can be configured with multiple stepwise tapers. In a preferred embodiment of the invention, the bottom frame includes a downwardly extended lip profile that abuts from below against the support wall. In this way, when the narrowed portion of the baking stone is seated on the bottom frame, it is possible to bring the stone closer to the flame spreader. This reduces the gap between the flame spreader and the baking stone, thereby enabling the flame to contact the baking stone directly even at the shortest flame length.

[0015] In a preferred embodiment of the invention, the baking stone includes a discharge channel extending from its lower portion to its upper portion. This discharge channel removes exhaust gases from the combustion environment of the burner and thereby helps improve the combustion efficiency of the gas burner.

[0016] In a preferred embodiment of the invention, the narrowed portion is arranged in circumferential adjacency to the bottom frame, and the discharge channel is configured to start from the lower portion and pass through the narrowed portion. Thus, if the narrowed portion sits against the bottom frame and closes off the airflow path for the gas burner, the discharge channel reopens the path and allows post-combustion exhaust gases to pass into the cooking chamber. Consequently, the baking stone can be used for cooking in the domestic oven without obstructing operation of the gas burner.

[0017] In a preferred embodiment of the invention, the discharge channel is formed in a transverse direction so as to reach the two opposite lateral edges of the baking stone. In this way, the heated exhaust airflow is discharged with high baking efficiency, without adversely affecting thermal distribution inside the oven.

[0018] In a preferred embodiment of the invention, the discharge channel is arranged near the corner portion of the opposing lateral edges. In this case, the discharge channels can be made relatively large, facilitating the release of hot air into the cooking chamber.

[0019] In a preferred embodiment of the invention, the discharge channel has a trapezoid-like shape that widens toward the lateral edge. In a surprisingly beneficial manner, this geometry has been observed to yield higher baking efficiency compared to other geometrical forms.

[0020] In a preferred embodiment of the invention, the lower portion of the baking stone has a flat and planar H-like shape. The H-like shape both provides the required structural strength and offers a maximum discharge area for airflow evacuation. In a preferred embodiment of the invention, the lower gas burner is aligned parallel to the rear wall and the access opening, at the center of the support sheet. In this way, a region of intense heat is generated along the short edge of the baking stone, and the baking stone then distributes that regionally concentrated heat outward in a manner that leads to a uniform temperature. It has been found that this arrangement prevents thermal shocks and prolongs the life of the baking stone.

[0021] In a preferred embodiment of the invention, the thickness of the baking stone starting from the support wall to the lateral edge is arranged to be in the range of 1-5 cm, in particular 1-3 cm. Within the stated range, the baking stone, for example made of sheet metal, has been found to operate stably in a standard domestic oven without causing any structural failure.

[0022] In a preferred embodiment of the invention, a blower fan is provided which is configured to move the air in the cooking chamber through an opening on a fan guard sheet fixed to the rear wall of the muffle. The blower fan not only prevents overheating of the baking stone due to the localized position of the flame spreader but also helps distribute the heat uniformly on the baking stone.

[0023] In a preferred embodiment of the invention, a flue accessible from the upper wall of the muffle is provided to discharge the air from the cooking chamber. The flue allows heated air from the gas burner and exhaust air taken from the baking stone’s discharge channel to be vented outside the muffle.

[0024] In a preferred embodiment of the invention, the side wall is provided with a tray carrier at a transverse distance from the opposing lateral edges of the baking stone so as not to obstruct it. Thus, for instance, the baking stone may be easily inserted into or removed from the muffle bottom frame opening in a diagonal manner.

[0025] BRIEF DESCRIPTION OF THE FIGURES

[0026] Figure 1 is a partial cross-sectional view in the transverse direction, showing the inventive domestic gas oven with the baking stone installed.

[0027] Figure 2 is a front cross-sectional view of the muffle of the gas oven shown in Figure 1 .

[0028] Figure 3 is an upper perspective view of a suitable baking stone for the gas oven. Figure 4 is a lower perspective view of the baking stone shown in Figure 3.

[0029] DETAILED DESCRIPTION OF THE INVENTION

[0030] In this detailed description, the invention is explained with references to examples solely for the purpose of clarification and without implying any limitation.

[0031] In Figure 1 , a metal housing (1 ) of a domestic gas oven and, inside the housing (1), a muffle (10) forming a front access opening (11) are shown in transverse cross-section. The muffle (10) is connected in fluid communication with a flue (2) that leads to an exhaust opening. A flange (3) extends outwardly in a straight line and surrounds the access opening (11 ) completely. A door (not shown) is hinged to the housing (1 ), and, during cooking, it leans against the flange (3) so as to block the access opening (11) of the muffle (10) and restrict access.

[0032] The muffle (10) has a conventional shape suitable for a domestic gas oven and includes two opposing side walls (12) made of flat sheet metal, an upper wall (18) covering the side walls (12) from above, a rear wall (15), and a bottom frame (14) that is parallel to the upper wall (18) and has an opening at its center. Between the housing (1 ) and the upper wall (18) of the muffle, there is an upper gas burner (70) seated on the upper wall (18); similarly, beneath the bottom frame (14) inside the muffle (10), there is a lower gas burner (20) mounted on a perforated support sheet (40) shaped like a bridge. A blower fan (60) has its propeller rotating inside the muffle (10) at the rear wall (15), with a motor shaft passing through a hole at the center of the rear wall (15). A fan guard sheet (16), which includes a circularly perforated diffuser (17) aligned with the fan blade, is spaced from the rear wall (15) and largely covers it. A tray carrier (50) in the form of a wire rack is mounted on the flat side walls (12). The tray carrier (50) is located on each of the two side walls (12) facing each other and keeps flat trays (not shown) guided by and supported along opposing edges on the side walls (12).

[0033] The bottom frame (14) is a sheet metal profile having a lip structure that extends inwardly around the perimeter of the bottom to form a circumferential frame. The bottom frame (14) is inclined outwardly. It is formed by cutting a rectangular shape out of a flat metal sheet. A baking stone (30) made of a monolithic ceramic slab with two-step thickness is seated on the bottom frame (14) so that its lower step abuts the inner circumference of the bottom frame (14) along the entire length. The upper portion (32) of the baking stone (30) is flat and planar. The lower portion (34) of the baking stone (30), facing the lower burner (20) and extending over the support sheet (40), sits directly on the bottom frame (14). In this arrangement, the flames released during combustion through the series of outlet holes of the flame spreader (22) of the lower gas burner (20) can reach the lower portion (34) of the baking stone (30) at least when the burner is set to its maximum flow rate. The flame spreader (22) is provided with linearly arranged, spaced outlet holes and is supplied with a gas-air mixture through a tube-shaped gas delivery pipe (24). The gas delivery pipe (24) is connected in fluid communication with a gas source (not shown) at the rear of the housing (1 ).

[0034] Figure 2 shows the combustion chamber formed between the support sheet (40) and the lower portion (34) of the baking stone (30) when the baking stone (30) is placed on the bottom of the muffle (10). Ambient air is supplied to the combustion chamber through perforated holes in the support sheet (40). When the lower gas burner (20) is supplied with gas, flames emerge in a row along the flame spreader (22) and extend the entire length, coming into direct contact with the lower portion (34) of the baking stone (30), thus heating it. The resulting hot air and exhaust gases need to be discharged from the combustion chamber. For this purpose, a discharge channel (33) is formed by carving out the opposing side edges at the lower portion of the baking stone (30). Consequently, the exhaust gases enter the interior of the muffle (10) to rise and eventually exit through the flue (2).

[0035] In Figure 3, the baking stone (30) is shown from an upper perspective. The outer periphery (31) of the baking stone (30) is a rounded rectangle. When seated on the bottom frame (14), the upper portion (32) provides a transversely extending flat cooking surface. The long edges of the baking stone (30) face forward and rearward in the muffle (10), while its short edges remain spaced from the side walls (12) and lie safely between the tray carriers (50). The discharge channel (33) on the short edges extends to the corner areas. The lower portion (34) of the baking stone (30), formed as a narrower section (35) beneath a support wall (36), is bounded by a side edge (37). The support wall (36) runs along the entire long edge from corner to corner, providing an abutment seat for the bottom frame (14). The lower portion (34) enclosed by the support wall (36) takes on an H-like form. As seen in Figure 4, the discharge channel (33) is shaped like a wedge that tapers inwardly. The discharge channel (33) starts from the lower portion (34) and extends to the short lateral edge (37), where it tapers in the outer periphery (31 ). To enhance resistance to thermal shock, the thickness of the baking stone (30) in the exit region of the discharge channel (33) is kept at least 5 mm. At the corner of the narrowed portion (34), spaced from the lateral edge (37), the stone transitions into a thinner corridor, rounded at the corner. In this way, the surface area by which the baking stone (30) is supported on the bottom frame (14) is increased, while also ensuring higher thermal shock resistance at the corners. The ratio of the narrowed portion (35) thickness to the total thickness at the lateral edge (37) is set to be less than 1 / 4. Under such conditions, the narrowed portion (35) is found not to adversely affect the uniform distribution of heat.

[0036] REFERENCE NUMERALS

[0037] 1 Housing 30 Baking stone

[0038] 2 Flue 31 Outer periphery

[0039] 3 Flange 32 Upper portion

[0040] 10 Muffle 33 Discharge channel

[0041] 11 Access opening 34 Lower portion

[0042] 12 Side wall 35 Narrowed portion

[0043] 14 Bottom frame 36 Support wall

[0044] 15 Rear wall 37 Lateral edge

[0045] 16 Fan guard sheet 40 Support sheet

[0046] 17 Diffuser 50 T ray carrier

[0047] 18 Upper wall 60 Blower fan

[0048] 20 Lower gas burner 70 Upper gas burner

[0049] 22 Flame spreader h Height

[0050] 24 Delivery pipe

Claims

CLAIMS1. A domestic gas oven comprising a muffle (10) that delimits a cooking chamber by means of opposing side walls (12), an upper wall (18), a rear wall (15), and a bottom frame (14) provided between them; and comprising a lower gas burner (20) equipped with a flame spreader (22) and provided beneath the bottom frame (14) on a support sheet (40) fixed to the muffle (10), characterized in that a baking stone (30) is arranged such that, when placed removably from a support wall (36) onto the bottom frame (14), the height (h) between the baking stone (30) and the flame spreader (22) is set so that the flames emitted from the flame spreader (22) directly reach a lower portion (34) of the baking stone (30).

2. A gas oven according to Claim 1 , wherein the baking stone (30) is a flat, planar monoblock slab made of ceramic, cordierite, clay, porcelain, natural stone, or metal.

3. A gas oven according to any one of the preceding claims, wherein the baking stone (30) includes a narrowed portion (35) that tapers from the support wall (36) so as to extend at least partially into the bottom frame (14).

4. A gas oven according to Claim 3, wherein the bottom frame (14) includes a downwardly extended lip profile abutting the support wall (36) from below.

5. A gas oven according to Claims 3 or 4, wherein the baking stone (30) includes a discharge channel (33) extending from its lower portion (34) toward its upper portion (32).

6. A gas oven according to Claim 5, wherein the narrowed portion (35) is arranged in circumferential adjacency to the bottom frame (14), and the discharge channel (33) is configured to start from the lower portion (34) and pass through the narrowed portion (35)7. A gas oven according to Claim 6, wherein the discharge channel (33) is formed in the transverse direction so as to extend to two opposite lateral edges (37) of the baking stone (30).

8. A gas oven according to Claim 7, wherein the discharge channel (33) is arranged adjacent to the corner portion at the opposing lateral edges (37).

9. A gas oven according to Claim 8, wherein the discharge channel (33) has a trapezoidal shape widening toward the lateral edge (37).

10. A gas oven according to any one of Claims 5-9, wherein the lower portion (34) of the baking stone (30) has a flat, planar H-like shape.

11. A gas oven according to any one of the preceding claims, wherein the lower gas burner (20) is aligned in parallel with the rear wall (15) and the access opening (11 ) at the center of the support sheet (40).

12. A gas oven according to any one of the preceding claims, wherein the thickness of the baking stone (30) from the support wall (36) to the lateral edge (37) is arranged in the range of 1-5 cm, in particular 1-3 cm.

13. A gas oven according to any one of the preceding claims, wherein it includes a blower fan (60) configured to move the air in the cooking chamber through an opening (17) provided on a fan guard sheet (16) fixed to the rear wall (15) of the muffle (10).

14. A gas oven according to any one of the preceding claims, wherein it includes a flue (2) accessible from the upper wall (18) of the muffle (10), through which air from the cooking chamber is exhausted.

15. A gas oven according to any one of the preceding claims, wherein the side wall (12) is provided with a tray carrier (50) at a transverse distance from the opposing lateral edges (37) of the baking stone (30) so as not to obstruct the baking stone.

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