Classifications

• • A—HUMAN NECESSITIES
  • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
  • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
  • A47J37/00—Baking; Roasting; Grilling; Frying
  • A47J37/12—Deep fat fryers, e.g. for frying fish or chips
  • A47J37/1266—Control devices, e.g. to control temperature, level or quality of the frying liquid

Definitions

• the present invention relates to electric cooking appliances, in particular but not exclusively to electric fryers intended for cooking, in a particular oil bath, of foods such as fries, fish or meat, and comprising a external housing in which a fixed or removable metal tank is incorporated, and electric heating means arranged under the tank and in thermal relation with the latter.
• a known safety device involves a temperature sensor which reacts to the temperature of the 2 heating means, in order to cut the electrical supply to the latter when the detected temperature of the heating means exceeds a predefined maximum temperature corresponding to an empty oil tank or insufficiently filled with oil.
• a sensor must be of high precision and reliability taking into account the high thermal powers provided in cooking appliances, which is difficult to obtain, and is relatively expensive.
• the object of the invention is in particular to remedy these drawbacks and to produce an electric cooking appliance, of the type set out above, in a simple and inexpensive manner, which has great operational safety with regard to any risk. linked to the absence of oil or to the insufficient quantity of oil in the tank.
• the device comprises detection means capable, on the one hand, of detecting a substantially vertical deformation of the bottom of the tank occurring during the operation of the device, under the effect of the 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 tank.
• the invention judiciously takes advantage of the vertical deformation that the bottom of the tank undergoes under the action of the heating produced below the tank, to quickly cut the heating if the tank is empty 3 of oil or is insufficiently filled with oil, thus offering an optimal guarantee of safety to the user; this vertical deformation of the bottom of the tank being effected in a sufficiently reproducible manner to be able to be used as a parameter of total or almost total lack of oil in the tank.
• the detection means are capable of detecting the relative deformation of the bottom of the tank occurring in the central region of the tank, compared to a so-called reference tank region which is located substantially at the outer edge of the bottom of the tank, and in which the bottom of the tank, during operation of the device, undergoes almost no deformation.
• the thermally almost non-deformable region of the tank itself advantageously constitutes in itself a real reference, and only one, to enable the deformation of the tank to be analyzed with precision, thereby avoiding taking into account all the rib chains entering into the constitution of the apparatus.
• the detection means comprise a system with two feeler members, namely a first feeler member which is in contact with the external face of the bottom of the tank, at a so-called zero reference point located in the reference region of the tank, and a second feeler member which is in contact with the external face of the bottom of the tank, in the center of the latter , so as to detect the relative deformation of the bottom of the tank with respect to the zero reference point, and which 4 is movable between a first position for which the detected relative deformation of the bottom of the tank reaches a level below the predetermined threshold, this level corresponding to a sufficiently filled tank, and in which it controls the closing of the electrical supply circuit of the means heating, and a second position for which the relative deformation detected from the bottom of the tank reaches the predetermined threshold corresponding to a substantially empty tank and in which it controls the opening of the electrical supply circuit of the heating means.
• the second movable feeler member is also capable of occupying a rest position for which the removable tank is absent in the housing and in which it controls the opening of the electrical supply circuit of the heating means, this second feeler member thus constituting a means suitable for detecting whether the removable tank is present or absent in the housing, and also, when the removable tank is present, for detecting whether the tank is sufficiently full or substantially empty.
• this second feeler member in itself constitutes a simple mechanical member, inexpensive, and which, moreover, advantageously fulfills the dual function of detecting the presence of the tank and filling the tank with a sufficient oil level.
• FIG. 1 is a partial schematic perspective view in vertical section of a cooking appliance, such as a fryer, according to the invention, comprising a tank associated with detection means shown in normal operation of the fryer;
• Figure 2 is a view similar to Figure 1, showing a deformation of the bottom of the tank when the latter is empty of oil;
• FIG. 3 shows as a function of time (in minutes) the deformation (in millimeters) of the bottom of the tank when the latter is sufficiently filled with oil and oil vacuum;
• Figure 4 is a view similar to Figure 1, in the absence of removable tank.
• the electric fryer intended for cooking food by immersion in a particular oil bath comprises, in an external housing 1, a metal tank 2 fixed or removable, by example of rectangular shape, intended to contain the oil bath for cooking food, as well as electric heating means, such as an armored heating resistor 4 which is arranged under the tank 2 and in thermal relation with this the latter for heating by conduction and / or by radiation from the tank 2.
• a metal tank 2 fixed or removable, by example of rectangular shape, intended to contain the oil bath for cooking food
• electric heating means such as an armored heating resistor 4 which is arranged under the tank 2 and in thermal relation with this the latter for heating by conduction and / or by radiation from the tank 2.
• the tank 2 is produced by stamping a sheet metal plate, for example made of steel, and 6 is then covered internally and externally with a heat-resistant coating, for example enamel, which makes it easier to clean the tank and avoid the adhesion of food on the inside surface of the tank. .
• a heat-resistant coating for example enamel
• the tank 2 has a flat bottom 6 under which the heating resistor 4 is in direct contact, which extends flat and advantageously has a serpentine shape suitable for promoting its contact thermal over the entire length and entire width of the bottom 6 of the rectangular tank 2 in this example.
• a thermal reflector (not shown) is arranged below the armored heating resistor 4, so that in operation, in this example, the armored resistor 4 provides heating of the tank 2 both by conduction and by radiation after reflection on the reflector.
• the electric fryer further comprises detection means, designated by the global reference 10 in FIGS. 1, 2 and 4, which are able, on the one hand, to detect a substantially vertical deformation of the bottom 6 of the tank 2 occurring during the operation of the fryer, under the effect of the heat produced by the heating resistor 4, and on the other hand, to open the electrical supply circuit of the heating resistor 4 when the deformation detected reaches a predetermined threshold corresponding to a tank 2 substantially empty of oil.
• the detection means 10 of this deformation advantageously constitute safety means for the operation of the fryer.
• the heating of the armored resistor 4 causes a substantial deformation of the bottom 6 of the metal tank 2 in the region central of the latter, and in a preferential direction due to the drawing of the tank 2 and which is directed towards the interior of the tank, as illustrated on an enlarged scale at 12 in FIG. 2, while the region of the tank located substantially on the outer edge 13 of the bottom 6 of tank 2 undergoes, for its part, almost no deformation.
• curve A shows, as a function of time t. the deformation D that the bottom 6 of the tank 2 undergoes, in this case enamelled steel, in the central region of the tank, identified at 15 in FIG. 1, during normal operation of the fryer, this is - ie tank 2 sufficiently filled with oil.
• the deformation D of the central region 15 of the bottom 6 of the tank increases steadily to stabilize at a value equal to 1 millimeter in this example.
• the deformation D of the central region 15 of the bottom 6 of the tank grows very rapidly to reach, approximately in 2 minutes, a value equal to 2.5 millimeters as indicated by point S_, and then come to stabilize at a value equal to 3.5 millimeters in this example.
• the predetermined threshold for the deformation of the bottom 6 of the tank 2 when the latter is empty of oil or insufficiently filled with oil, and for which the detection means 10 are able to open the circuit of power supply of the heating resistor 4, is chosen, in this example, equal to 2.5 millimeters.
• the detection means 10, FIGS. 1 and 2 are capable of detecting the relative deformation of the bottom 6 of the tank 2, in the central region 15 thereof, relative to the tank region, called the reference region and identified at 17 in FIGS. 1 and 2, which is located on the outer edge 13 of the bottom 6 of the tank, and which undergoes almost no deformation during the operation of the fryer.
• the fact of taking into account the tank itself as a reference, at the level of its region 17 almost without deformation makes it possible to analyze with great precision the deformation of the bottom 6 of the tank during the operation of the fryer, and therefore of get rid of all the rib chains of the various elements of constitution of the fryer.
• the detection means 10 comprise a mechanical system with two feeler members 21, 22 respectively comprising a first lever 24 and a second lever 25 which are associated one with the other by being pivotally mounted around the same fixed axis 27 arranged in the housing 1, and 9 which consist respectively of two vertical uprights 29, 30 applied against each other while being crossed at their respective upper ends by the axis 27, and having respectively, at two different levels, two parallel transverse arms 32, 33 extending along the width of the tank 2 and having respectively, at their respective free ends, two vertical fingers forming feelers 35, 36 in permanent point contact against the external face of the bottom 6 of the tank 2, one (35) at a point R called zero reference located in the reference region 17 of the tank 2, the other (36) in the center C of the tank, see Figure 1.
• the two levers 24, 25 are urged together by the same member return elastic 38, such as a calibrated spiral spring, one end of which is fixed in the housing 1, and the other end of which is anchored to the free end of the arm 32 of the lever 24.
• the tilting lever 25 is likely to occupy a first position (FIG. 1) for which the relative deformation detected at the center C of the tank 2 relative to the zero reference point R, during operation of the fryer , reaches a level below the predetermined threshold, chosen in this example equal to 2.5 millimeters, and therefore corresponding to a tank 2 sufficiently filled with oil, and in which it controls a safety switch 40 so as to close the circuit d electrical supply of the heating resistor 4, as well as a second position (FIG. 2) obtained by a larger tilting and for which the detected deformation D of the bottom 6 of the tank 2, at the center C of the tank relative to the point zero R, reaches or exceeds the predetermined threshold, i.e. 2.5 10 millimeters in this example, and therefore corresponding to a tank 2 empty of oil or insufficiently filled with oil, and in which it controls the switch 40 so as to open the electrical supply circuit of the heating resistor 4.
• a first position for which the relative deformation detected at the center C of the tank 2 relative to the zero
• the safety switch 40 is for example of the normally closed type and comprises a movable control button 42 (FIG. 1), the operation of which opens the contacts; this switch 40 has electrical connections 43, 44 intended to be connected to the electrical supply circuit of the heating resistor 4.
• a tension spring 48 is interposed, in a direction parallel to that of the two arms 32, 33 of the two levers 24, 25, between two spacers 50, 51 formed respectively on the two vertical uprights 29, 30 of the two levers 24, 25, 11 so as to maintain the tab 46 of the lever 25, either at a distance from the button 42 of the switch 40 when the lever 25 is in its first position (FIG. 1), or by pressing against the button 42 of the switch 40 when the lever 25 is in its second position ( Figure 2).
• the lever 25 is also capable of occupying by tilting upwards a rest position (FIG. 4) for which the tank 2 is absent in the housing 1 and in which its tab 46 presses the button 42 of the switch 40 so as to allow the opening of the electrical supply circuit of the heating resistor 4.
• this rocking lever 25 advantageously constitutes a simple mechanical part capable of detecting whether the removable tank 2 is present or absent in the housing 1, and also, when the removable tank is present, of detecting whether the tank 2 is sufficiently filled with oil or vacuum.
• the operation of the detection means 10 according to the invention is as follows.
• the two levers 24, 25 each occupy a rest position illustrated in FIG. 4 and in which the respective upper ends of their fingers 35, 36 are located in the same horizontal plane while being held there under the action of the correctly calibrated return spring 38.
• the tab 46 depresses the button 42 of the switch 40, thus allowing in this example to open the electrical supply circuit of the heating resistor 4; this will prevent the fryer from operating.
• the two levers 24, 25 are actuated by the bottom 6 of the tank 2 and switch counterclockwise, at against the return spring 38, so that their fingers 35, 36, through their upper end, are always in contact with the external face of the bottom 6 of the tank 2, respectively at the zero reference point R and at the center C of the tank.
• the tab 46 of the latter deviates from the button 42 of the switch 40, thus allowing the closing of the electrical supply circuit of the heating resistor 4, see FIG. 1.
• the lever 25, by its feeler finger 36, permanently follows the relative deformation which the bottom 6 of the tank 2 undergoes, at the center C thereof, relative to the reference point zero R.
• the deformation of the bottom 6 of the tank 2 is less than the predetermined threshold, in this case 2.5 millimeters, and is therefore not sufficient to actuate the switch 40.
• the two levers 25, 26 therefore remain practically each in their first position as illustrated in FIG. 1. 13
• the deformation D of the bottom 6 of the tank 2 quickly reaches the predetermined threshold, namely 2.5 millimeters, as illustrated in FIG. 2, and the lever 25 then switches clockwise to come to occupy its second position in which its tab 46 depresses the button 42 of the switch 40, thus allowing the opening of the electrical supply circuit of the heating resistor 4, as shown in FIG. 2.
• the detection means 10 described above and constituted by mechanical means can also be constituted by optical or magnetic means making it possible to determine the presence of the removable tank in the housing, as well as the filling level oil in the tank by analysis of the deformation of the bottom thereof, without departing from the scope of the invention.

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• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Frying-Pans Or Fryers (AREA)

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• 1998
  • 1998-02-25 FR FR9802871A patent/FR2775178B1/fr not_active Expired - Fee Related
• 1999
  • 1999-02-23 EP EP99906302A patent/EP1056383A1/de not_active Withdrawn
  • 1999-02-23 WO PCT/FR1999/000426 patent/WO1999043245A1/fr not_active Application Discontinuation
  • 1999-02-23 CN CN99805045.8A patent/CN1297339A/zh active Pending
  • 1999-02-23 US US09/622,977 patent/US6240835B1/en not_active Expired - Fee Related

Non-Patent Citations (1)

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