Stoves and furnaces – Stoves – Cooking
Reexamination Certificate
2002-10-21
2004-07-27
Lu, Jiping (Department: 3749)
Stoves and furnaces
Stoves
Cooking
C126S02100R, C126S080000, C126S08500R
Reexamination Certificate
active
06766796
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a heat exchanger for forced air circulation ovens, particularly but not exclusively useful for baking food.
Many models of ovens with forced circulation of hot air are currently commercially available and have a substantially common basic structure.
Ovens with forced circulation of hot air in fact have substantially two chambers, a baking chamber and a heat exchange chamber, between which air is circulated by means of one or more fans.
Inside the heat exchange chamber, heat is transferred from a heating means (usually a burner or an electric resistor) to the air, while in the baking chamber heat is transferred from the air to the food.
Commercially available forced circulation ovens differ substantially in the manners in which they perform the heat exchange between the heating means or medium and the air and between the air and the food.
Ovens that use electric resistors, despite being widely used, have the considerable and inevitable drawback of using a form of energy (electric power) of high quality for a merely thermal application.
Among ovens that use gas burners, some perform the heat exchange inside the baking chamber by means of tube bundles arranged vertically or so as to surround the ventilation means.
The execution of the tube bundles and of the end manifolds provided together with them (a lower one which contains the burner, and an upper one, for collection and toward the flue) entails processes that are certainly not easy and welds that constitute weakening regions, taking into account the expected operating conditions.
The high temperatures in fact produce thermal stresses due to the considerable differences in temperature among the various regions, which lead to tensions in the material and to breakage in the weaker parts.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide a heat exchanger for forced air circulation ovens that eliminates the drawback noted above.
Within this aim, an object of the present invention is to provide a heat exchanger whose structure is simple and can be manufactured by way of known technologies.
Another object of the present invention is to provide a heat exchanger that thanks to its constructive simplicity is less expensive than known ones.
This aim and these and other objects that will become better apparent hereinafter are achieved by a heat exchanger for forced air circulation ovens, particularly for baking foods, of the types that comprise two chambers, a baking chamber and a heat exchange chamber, between which at least one fan circulates the air, having a structure that is characterized in that it comprises a box-like body that contains burner means and is provided, in an upward region, with coupling connectors that have an oval profile and are inserted in corresponding complementarily shaped straight vertical tubes that end in an upper manifold, the end portion of each one of said tubes being surrounded by an interspace that is formed by a portion of tube that connects said heat exchange chamber to said manifold.
REFERENCES:
patent: 3831579 (1974-08-01), Tamada et al.
patent: 5619983 (1997-04-01), Smith
patent: 94 16 205 (1994-12-01), None
patent: 0 576 385 (1993-12-01), None
patent: 0 599 103 (1994-06-01), None
Bassan Antonio
Franzolin Enrico
Josif Albert
Lu Jiping
Modiano Guido
O'Byrne Daniel
Unox S.p.A.
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