A gas oven having an auxiliary exhaust opening

Abstract

The invention relates to an oven comprising a muffle (10) having an upper wall (11) and provided with an exhaust opening (12); an upper burner (20) arranged within the muffle (10) adjacent to the upper wall (11); and a fan housing (30) arranged externally on the upper wall (11) of the muffle (10) and forming an exhaust duct (34) which, in an operating mode in which the upper burner (20) is activated, directs the waste gas drawn through the exhaust opening (12) toward an outlet end (32) at the front of the muffle (10) by means of a fan (40) so as to form an exhaust air flow (f). The oven comprises at least one auxiliary exhaust opening (14) provided in the upper wall (11) at a distance from the exhaust opening (12), the auxiliary exhaust opening (14) being in fluid access to the exhaust duct (34) so as to convey waste gas from within the muffle (10) into the exhaust duct (34) by virtue of the Venturi effect created by the air flow (f).

Description

[0001] A GAS OVEN HAVING AN AUXILIARY EXHAUST OPENING

[0002] TECHNICAL FIELD

[0003] The invention relates to an oven, particularly a gas oven, having an upper burner within a muffle, and in which waste gas is discharged, by means of a fan housing, through a fume outlet provided above the door.

[0004] BACKGROUND ART

[0005] Domestic cooking appliances generally include a metal chamber referred to as a muffle, and this chamber discharges the gases generated during cooking via a fume outlet opening provided in its upper wall. In front of the muffle, there is a door hinged to the casing, which is used to open and close the cooking chamber. In the upper portion of the casing, there is a duct system or chimney arranged to discharge fumes to the front. Said duct is defined on a flue positioned between the muffle and the duct, and in most designs an fume outlet is provided in the front region of the duct, close to the upper edge of the door.

[0006] A ventilation arrangement is used in order to accelerate the hot fume flow exiting the cooking chamber and to cool the door compartment. In common embodiments, this is achieved by a tangential fan typically located in the rear or upper region of the appliance. In addition, in some ovens, fresh air is drawn in from the front of the oven and mixed with the fumes exiting the muffle, and this mixture is directed to the external environment through an outlet on the front side of the duct. In this way, it is aimed both to reduce the fume temperature and to reduce the surface temperature of the door by circulating air between the door panels. However, in existing designs, positioning the tangential fan far from the flue prevents the formation of a high vacuum level (negative pressure) within the flue; as a result, a larger outlet opening is required, which is notable as a factor that increases heat loss.

[0007] US2016273780 discloses a domestic cooking appliance, in particular an oven, comprising a cooking chamber defined by a muffle having a flue opening in its upper wall, and a front door for opening and closing said chamber. The appliance further comprises an exhaust duct defined by a duct body extending over the upper wall of the muffle. The duct body has, in the front region of the appliance, an exhaust outlet located above the upper portion of the door, and also has a fume inlet located in a lower wall of the duct body and providing fluidcommunication between the muffle flue opening and the exhaust duct. A ventilation arrangement is coupled to the duct body, and operates to draw fumes exiting the muffle and discharge them through the exhaust outlet of the exhaust duct; a rear end region in which the ventilation arrangement is arranged is generally located opposite the exhaust outlet of the exhaust duct. The ventilation arrangement comprises a radial fan (centrifugal impeller fan) located within the duct body. The centrifugal impeller of the fan is positioned immediately above the fume inlet, substantially coaxially with said inlet and the muffle flue opening. Thus, at least the fumes exiting the muffle are drawn along the axis of the impeller and are conveyed radially into the exhaust duct, and are discharged from there to the external environment. The rear end region of the duct body has a generally rounded peripheral profile so as to form the volute of the radial fan; the duct body is preferably designed to taper toward its rear portion and includes two shells (half-housings), namely a lower and an upper shell. Furthermore, within the duct body there is a flow-deflecting element positioned within the boundaries of the exhaust duct, for distributing more uniformly into the exhaust duct the flow generated by the centrifugal impeller.

[0008] SUMMARY OF THE INVENTION

[0009] An object of the invention is to improve the waste-gas discharge efficiency in an oven.

[0010] In order to achieve the above objective, the invention relates to an oven comprising, a muffle having an upper wall and provided with an exhaust opening; an upper burner arranged within the muffle adjacent to the upper wall; and a fan housing arranged externally on the upper wall of the muffle and forming an exhaust duct, the fan housing being configured, in an operating mode in which the upper burner is activated, to direct the waste gas drawn through the exhaust opening toward an outlet end located at the front of the muffle by means of a fan so as to form an exhaust air flow. The oven comprises at least one auxiliary exhaust opening provided in the upper wall at a distance from the exhaust opening, the auxiliary exhaust opening being in fluid access to the exhaust duct such that waste gas from within the muffle is conveyed into the exhaust duct by means of the Venturi effect created by the air flow. Since the auxiliary exhaust opening provides a waste-gas discharge using the air flow already generated by the ventilation arrangement, it enables a more homogeneous, multipoint waste-gas evacuation from the muffle without adversely affecting the overall energy efficiency of the system.Preferably, the auxiliary exhaust opening is arranged in the upper wall at a vicinity of a front end of the upper burner. In this way, waste gases formed around the front end of the upper burner are transferred directly into the exhaust duct without circulating within the muffle.

[0011] Preferably, the exhaust opening is arranged in the upper wall adjacent to a rear end of the upper burner that is opposite the auxiliary exhaust opening. In this case, while waste gases at the front end are discharged through the auxiliary exhaust opening, waste gases formed at the rear part of the upper burner are discharged from the rear of the muffle; thus, waste gas is collected and discharged from two opposing ends of the muffle. In this way, waste-gas evacuation from opposing ends, namely from the front and from the rear, becomes possible.

[0012] Preferably, in alignment with the auxiliary exhaust opening, the fan housing is configured such that the transverse cross-section of the exhaust duct narrows toward the outlet end so as to accelerate the exhaust air flow. In this way, the exhaust air flow that accelerates toward the outlet end increases the negative pressure at the auxiliary exhaust opening, thereby enabling suction at a higher volumetric flow rate. Waste-gas evacuation is performed in a balanced manner from the front and the rear of the muffle.

[0013] Preferably, a primary flue is provided, extending from the exhaust opening to the fan housing so as to form a duct through which the muffle waste gas passes. The primary flue increases the vacuum level by providing a bounded duct and facilitates the fan suction of the waste gas coming from the exhaust opening.

[0014] Preferably, a secondary flue is provided, extending from the auxiliary exhaust opening to an inlet opening in a lower wall of the fan housing so as to form a duct through which the muffle waste gas passes. The secondary flue enables the waste gas to be conveyed in a controlled manner to the exhaust duct by routing it through a defined cross-sectional area. The cross-sectional form of the secondary flue is likely adjusted to an extent that allows the exhaust air flow passing through the exhaust duct to generate negative pressure at the auxiliary exhaust opening.

[0015] Preferably, the secondary flue has a conical form. In this way, waste gases within the muffle access the exhaust airflow without generating turbulence and without increasing noise.

[0016] Preferably, the fan is a radial fan having a radial impeller arranged, along its height, within the exhaust duct. The radial fan allows the exhaust duct to be configured in a compact and low-profile structure and, since it operates on a centrifugal principle rather than axial suction,it generates a higher negative pressure at the flue opening. In this way, the gases in the muffle or cooking chamber are evacuated more effectively and rapidly.

[0017] Preferably, the fan housing is of a low-profile (flat) form, and the outlet end is aligned with an air outlet between the upper edge of the door and the front panel. In this way, a fan housing is provided which can be easily placed along the upper wall of the muffle and which has an internal volume capable of guiding the waste-gas discharge in a controlled manner to the outlet end without backflow.

[0018] Preferably, the upper burner is a gas burner. In this way, in a gas oven, for example an upper gas burner used for grilling can receive sufficient combustion air and the waste gases generated can be safely discharged from the muffle from multiple points.

[0019] Preferably, a raised portion is provided which bends from a front part of the muffle upper wall toward the fan housing, and within which the upper burner is placed so as to extend longitudinally along its entire length. The raised portion forms a pocket for concealing the upper burner within the muffle. In this case, when the door is opened, the upper burner is not visible. Moreover, waste-gas evacuation becomes possible in a manner that meets the requirements of relevant technical standards, in accordance with the flow dynamics created by the pocket.

[0020] Preferably, a hanger element is provided at the front edge of the raised portion and supports the upper burner from its front end. The hanger element enables the upper burner to be suspended from the front of the muffle; since it remains within the raised portion, the upper burner is concealed in the cooking chamber when the door is opened together with the upper burner.

[0021] BRIEF DESCRIPTION OF THE FIGURES

[0022] Figure 1 is a perspective representation of an exemplary configuration of the oven according to the invention.

[0023] Figure 2 is a cross-sectional representation of a gas built-in oven in which the exhaust opening is provided on the rear portion of the muffle and the auxiliary exhaust opening is provided on the front portion of a gas upper burner.DETAILED DESCRIPTION OF THE INVENTION

[0024] In this detailed description, the improvement according to the invention is explained by reference to examples, without any limitation, and solely to better describe the subject matter.

[0025] In Figure 1, a gas built-in oven is shown in perspective with a door (3) in the closed position, the door allowing access to the cooking chamber. The oven comprises a prismatic casing (4), a front panel (1) located at the front portion of the casing, and a hinged door (3) located beneath the front panel (1). An air outlet (2) is provided between the upper straight edge of the door (3) panel and the parallel straight lower edge of the front panel (1 ).

[0026] In Figure 2, a muffle (10) equipped with a fan housing (30) having an outlet end (32) providing internal access to the air outlet (2) is shown in cross-section. The muffle (10) surrounds the cooking chamber with flat and low-profile walls made of metal material. The open end (17) of the muffle (10), which is open and externally accessible, is sealed by an inner panel of the door (3), the door being formed of spaced panels. Support elements are fixed on opposite side walls of the muffle (10) in order to guide and place trays. An upper wall (11) of the muffle (10), starting from the open end (17), rises in its inlet region to form a raised portion (16) in the form of a pocket structure. The raised portion (16) extends straight from the open end (17) to the rear wall. A gas grill burner has a flat and thin form as an upper burner (20) and extends horizontally along its entire length within the raised portion (16). In this manner, a front end (22) of the upper burner (20) is positioned adjacent to a front end of the raised portion (16). By forming a hole in the rear end of the upper wall (11), an exhaust opening (12) is provided. A rear end (24) of the upper burner (20), which is opposite the front end (22), is positioned facing the exhaust opening (12). The exhaust opening (12) is surrounded by an inlet (54) of a primary flue (50). The primary flue (50) has the form of a bent duct of constant cross-section and turns the air flow coming from the exhaust opening (12) in the upper wall (11) substantially perpendicularly, directing it forward to an outlet (52). The outlet (52) of the primary flue (50) feeds an air inlet of a plastic fan housing (30) that accommodates a fan (40) and defines the exhaust duct (34). A conical secondary flue (60), tapering upward, is adapted to the auxiliary exhaust opening (14) in a sealed manner. A narrowing throat (62) of the secondary flue (60) extends upward in the distance between the upper wall (11 ) and a lower wall of the fan housing (30), and is fixed in a sealed manner at its upper outlet (64) to the front inlet opening (36). Thus, the secondary flue (60) forms an air passage duct between the auxiliary exhaust opening (14) and the fan housing (30). The fan housing (30) has a form that is high at its rear portion so as to permit accommodation of the fan (40), and narrowing at its front portion. The fan (40) is a radial fan. An impeller (42) of thefan (40), having rotating blades, extends vertically adjacent to the lower and upper edges of the fan housing (30). One end of the impeller (42) of the fan (40) faces an inlet (38) fed by the outlet (52) of the primary flue (50), while the opposite end faces the open end of the narrowing portion of the fan housing (30). Accordingly, when the fan (40) is activated while the gas upper burner (20) is operating, it generates an exhaust airflow (f) due to the negative pressure created at the inlet (38) of the exhaust duct (34). In this case, the volumetric flow rate of the exhaust air flow (f) is determined depending on the rotational speed of the fan (40).

[0027] When the fan speed reaches a predetermined level, the acceleration of the exhaust airflow (f) in the narrowing portion of the exhaust duct (34) increases the negative pressure at the front inlet opening (36) to a level sufficient for exhausting air through the secondary flue (60). In this case, waste gases — such as carbon-containing combustion gases that may form at the upper burner (20) and greasy vapors generated in the muffle (10) due to cooking — are drawn both through the exhaust opening (12) and through the auxiliary exhaust opening (14) and are admitted into the exhaust duct (34). The exhaust air flow (f) formed by the fan (40) in the exhaust duct (34) in the form of an air jet is discharged from the outlet end (32) as a combination of the waste gases joining first from the primary flue (50) and then from the secondary flue (60); from there it reaches the air outlet (2) and thereby accesses the external environment. The auxiliary exhaust opening (14) located in the portion of the raised portion (16) close to the front end (22) is positioned closer to the exhaust duct (34) relative to the open end (17). In this way, the vacuum formed by the exhaust air flow (f) at the front inlet opening (36) while advancing within the exhaust duct (34) is sufficient to evacuate waste gas via the short secondary flue (60). The cross-sectional area of the exhaust duct (34) reaches its minimum dimension after the outlet (64) of the secondary flue (60). The exhaust duct (34) extends over the inclined portion of the raised portion (16) on the upper wall (11) in a straight and constant cross-sectional form, being reduced to the width of the air outlet (2) and reaching the outlet end (32). In the configuration shown in Figure 2, waste gases are collected in the regions of the muffle (10) where the fumes are most concentrated, namely at the front and rear portions of the upper wall (11) near the respective front end (22) and rear end (24) of the upper burner (20), via the connections of the secondary flue (60) and primary flue (50) respectively, and are thereby incorporated into the exhaust airflow (f).

[0028] REFERENCE NUMERALS

[0029] 1 Front panel 30 Fan housing

[0030] 2 Air outlet 32 Outlet end

[0031] 3 Door 34 Exhaust ductCasing 36 Front inlet opening Muffle 40 Fan

[0032] Upper wall 42 Impeller Exhaust opening 50 Primary flue Auxiliary exhaust opening 52 Outlet Raised portion 54 Inlet

[0033] Open end 60 Secondary flue Hanger element 62 Throat Upper burner 64 Outlet

[0034] Front end f Exhaust air flow Rear end

Claims

CLAIMS1. An oven comprising a muffle (10) having an upper wall (11) and provided with an exhaust opening (12); an upper burner (20) arranged within the muffle (10) adjacent to the upper wall (11); and a fan housing (30) arranged externally on the upper wall (11) of the muffle (10) and forming an exhaust duct (34) which, in an operating mode in which the upper burner (20) is activated, directs the waste gas drawn through the exhaust opening (12) toward an outlet end (32) at the front of the muffle (10) by means of a fan (40) so as to form an exhaust air flow (f) characterized by at least one auxiliary exhaust opening (14) provided in the upper wall (11) at a distance from the exhaust opening (12), the auxiliary exhaust opening (14) being in fluid access to the exhaust duct (34) so as to convey waste gas from within the muffle (10) into the exhaust duct (34) by means of the Venturi effect created by the air flow (f).

2. The oven according to claim 1, wherein the auxiliary exhaust opening (14) is arranged in the upper wall (11 ) at a vicinity of a front end (22) of the upper burner (20).

3. The oven according to claim 2, wherein the exhaust opening (12) is arranged in the upper wall (11) adjacent to a rear end (24) of the upper burner (20) that is opposite the auxiliary exhaust opening (14).

4. The oven according to any one of the preceding claims, wherein, a transverse crosssection of the exhaust duct (34) narrows toward the outlet end (32) so as to accelerate the exhaust air flow (f) in the fan housing (30) in alignment with the auxiliary exhaust opening (14).

5. The oven according to any one of the preceding claims, wherein a primary flue (50) extending from the exhaust opening (12), to which it is fixed, toward the fan housing (30) so as to form a duct through which the muffle (10) waste gas passes.

6. The oven according to any one of the preceding claims, wherein a secondary flue (60) extending from the auxiliary exhaust opening (14), to which it is fixed, to an inlet opening (36) in a lower wall of the fan housing (30) so as to form a duct through which the muffle (10) waste gas passes.

7. The oven according to claim 6, wherein the secondary flue (60) has a conical form.

8. The oven according to any one of the preceding claims, wherein the fan (40) is a radial fan having a radial impeller (42) arranged, along its height, within the exhaust duct (34).

9. The oven according to any one of the preceding claims, wherein the fan housing (30) has a low-profile form, and the outlet end (32) is aligned with an air outlet (2) between an upper edge of the door (3) and the front panel (1 ).

10. The oven according to any one of the preceding claims, wherein the upper burner (20) is a gas burner.

11. The oven according to claim 10, wherein a raised portion (16) that bends from a front portion of the upper wall (11) of the muffle (10) toward the fan housing (30), and within which the upper burner (20) is placed so as to extend longitudinally along its entire length12. The oven according to claim 11, wherein a hanger element (18) provided at a front edge of the raised portion (16) and supporting the upper burner (20) from its front end (22).

Images