Foods and beverages: apparatus – Cooking – Automatic control
Reexamination Certificate
2000-10-12
2001-06-05
Simone, Timothy F. (Department: 1761)
Foods and beverages: apparatus
Cooking
Automatic control
C099S337000, C099S336000, C099S403000, C099S407000
Reexamination Certificate
active
06240835
ABSTRACT:
The present invention relates to electric cooking apparatus, particularly but not exclusively to electric deep fryers adapted for cooking, particularly in an oil bath, of foodstuffs such as fried potatoes, fish or meat, and comprising an external housing in which are incorporated a metallic vat, fixed or removable, and electric heating means disposed below the vat and in heat exchange relation with this latter.
BACKGROUND OF THE INVENTION
During the use of such a cooking apparatus, for example a deep fryer, there always exists the risk that the user will forget to refill the vat with oil and will start the frying operation, thus rapidly leading to damage to the vat, such as, for example, cracking or sublimation of the coating which is generally used to facilitate the cleaning of the vat and which internally and externally covers this latter, even to ignition of the deep fryer due to the presence of a film of residual oil on the internal walls of the vat.
To overcome these drawbacks, and hence to ensure the safety of the user and to avoid any damage to the apparatus, it has been proposed to provide such a cooking apparatus with a safety device permitting preventing activation of the electric heating means when the vat, present in the housing, is empty of oil or does not contain sufficient oil. A known safety device uses a temperature detector which reacts to the temperature of the heating means, so as to cut off the electrical supply to the latter when the detected temperature of the heating means exceeds a predetermined maximum temperature corresponding to a vat empty of oil or insufficiently filled with oil. However, to perform correctly its temperature detection function, such a detector must be highly precise and highly reliable, given the high heating powers associated with cooking apparatus, which is difficult to obtain and relatively cumbersome.
SUMMARY OF THE INVENTION
The invention has particularly for its object to overcome these drawbacks and to provide in a simple and less costly way an electric cooking apparatus, of the type described above, which has a high safety of operation as to any risk connected with the absence of oil or a too small quantity of oil in the vat.
According to the invention, the apparatus comprises detection means adapted on the one hand to detect a substantially vertical deformation of the bottom of the vat that takes place during operation of the apparatus, under the influence of heat produced by the heating means, and on the other hand to open the electrical supply circuit of the heating means when the detected deformation reaches a predetermined threshold corresponding to a substantially empty vat.
Thus, the invention takes advantage of the vertical deformation to which the bottom of the vat is subject during heating action produced below the vat, rapidly to cut off the heating if the vat is empty of oil or insufficiently filled with oil, thereby giving optimum guarantee of safety to the user; this vertical deformation of the bottom of the vat taking place in a sufficiently reproducible manner to be able to use it as a parameter for the total or almost total absence of oil in the vat.
According to another important characteristic of the invention, the detection means are adapted to detect the relative deformation of the bottom of the vat that takes place in the central region of the vat, relative to a so-called reference region of the vat which is located substantially on the external border of the base of the vat, and in which the bottom of the vat, during operation of the apparatus, is subject to almost no deformation. Thus, the substantially thermally undeformable region of the vat itself constitutes preferably a true reference, and the only one needed, to permit analyzing with precision the deformation of the vat, thereby making it unnecessary to take into account all the other areas of the construction of the apparatus.
According to a preferred embodiment of the invention, the deformation of the bottom of the vat taking place internally of the vat, the detection means comprise a system of two detection members, namely a first detection member which is in contact with the external surface of the bottom of the vat, at a so-called zero reference point located in the reference region of the vat, and a second detection member which is in contact with the external surface of the bottom of the vat, at the center of this latter, so as to detect the relative deformation of the bottom of the vat with respect to the zero reference point, and which is movable between a first position in which the detected relative deformation of the bottom of the vat reaches a level below the predetermined threshold, this level corresponding to a sufficiently filled vat, and in which it controls the closing of the electrical supply circuit of the heating means, at a second position in which the detected relative position of the bottom of the vat reaches the predetermined threshold corresponding to a substantially empty vat and in which it controls the opening of the electrical supply circuit of the heating means.
In this embodiment of the invention, and in the case of a removable vat, the second movable detection member is also adapted to occupy a rest position in which the movable vat is absent from the housing and in which it controls the opening of the electrical supply circuit of the heating means, this second detection member thus constituting a means adapted to detect whether the removable vat is present or absent in the housing, and also, when the removable vat is present, to detect whether the vat is sufficiently filled or is substantially empty. Thus, this second detector member constitutes itself a simple mechanical member, less costly, and which, moreover, preferably fulfills the double function of detection of the presence of the vat and of the filling of the vat to a sufficient level with oil.
REFERENCES:
patent: 3839951 (1974-10-01), Palmason
patent: 5740721 (1998-04-01), Bizard
patent: 598 794 (1978-05-01), None
patent: 0 341 606 (1989-11-01), None
patent: 2 724 835 (1996-03-01), None
patent: WO 96/05761 (1996-02-01), None
Bois Bernard Marcel
Giffard Sylvain
Sibarita Romain
Moulinex (S.A.)
Simone Timothy F.
Young & Thompson
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