WO2002000077A2

WO2002000077A2 - Heating container for electrical household immersion heaters

Info

Publication number: WO2002000077A2
Application number: PCT/FR2001/002040
Authority: WO
Inventors: Yves Libis
Original assignee: Seb S.A.
Priority date: 2000-06-27
Filing date: 2001-06-27
Publication date: 2002-01-03
Also published as: AU2001270677A1; WO2002000077A3; FR2810526B1; FR2810526A1; EP1294261A2

Abstract

The invention concerns an electrically heating container for household immersion heaters, in particular for frying, comprising a vessel (2; 2'; 2''; 2'''), a heating element (6; 26; 36; 46) fixed beneath a distribution plate (5; 25; 35; 45), made of good heat conducting material and fixed beneath a part made of stainless steel of the vessel base, and a temperature control member (14). The invention is characterised in that the temperature control member (14) is in thermal contact with a diffusing plate (11; 21; 31; 41) made of good heat conducting material, fixed on an outer surface of the vessel (2; 2'; 2''; 2''') in said part made of stainless steel, and the heat exchanges by conduction between the distribution plate (5; 25; 35, 45) and the diffusing plate are produced through the vessel, and as the case may be, through at least a thermal bridge (48, 48') connecting the distribution plate (45) to the diffusing plate (41).

Description

HEATING CONTAINER FOR HOUSEHOLD APPLIANCE

LIQUID HEATERS

The present invention relates to the general technical field of household appliances intended for heating liquids. The present invention relates more particularly, but not exclusively, to the container and to the heating and regulation system of an apparatus intended to heat oil in a temperature range between 150 and 210 ° C.

Stainless steel is a food material having interesting properties for producing a container for a liquid heating appliance. The abrasion resistance is better than that of a PTFE coating covering the interior walls of an aluminum container, and the adhesion to the walls of the deposits formed during the heating of the liquid is weaker than that obtained with a container whose inner walls are not coated. However, stainless steel has a much lower thermal conductivity than aluminum.

To obtain a satisfactory transmission of the calories released by the heating element to the liquid to be heated, it has been proposed to immerse a heating element as well as a member for regulating the temperature in the liquid contained in the container. However, such a construction has the drawback of reducing the useful volume of the container and making cleaning of the container more difficult.

It has also been proposed in document US Pat. No. 4,138,606 to produce an electric fryer comprising a heating element brazed on a support plate itself brazed on the bottom wall of a stainless steel container. A thermostat is mounted on a brazed screw under the bottom of the container. Such a construction makes it possible to avoid the abovementioned drawbacks while retaining the properties of a stainless steel container. However, even using a support plate made of a material which is a good thermal conductor, such as aluminum, such a construction has the disadvantage of leading to a lower oil bath temperature for the first cut of the thermostat than for the following cuts. However, the thermostat is often associated with an indicator light to indicate to the user that the oil bath has a sufficient temperature for cooking, and an insufficient oil bath temperature gives fried foods that are fatter and less crisp. A construction leading to a lower oil bath temperature when the thermostat is first switched off is therefore not satisfactory.

It is known to produce an electric fryer comprising a heating element fixed on an aluminum support plate itself fixed on the bottom wall of a stainless steel container, in which the regulating means comprise a first thermostat mounted close to the heating element and a second thermostat mounted on the support plate. The first thermostat limits the temperature of the heating element and the second thermostat limits the temperature of the oil bath. Such a construction makes it possible to avoid the abovementioned drawback but is more expensive.

It is known from document FR 2 731 607 to produce a stainless steel tank on the bottom of which is mounted an aluminum plate supporting a heating element and a thermostat. Such a construction makes it possible to obtain satisfactory regulation performance but has the disadvantage of being expensive.

It is known from document GB 2 337 919 to make a container for heating liquids, in particular for boiling water, comprising a stainless steel bottom covered with a thermal diffusion plate under which are fixed a heating element as well as control members. of the temperature. However, if the proposed construction is well suited to the detection of dry heaters, it appears unsuitable for regulating an oil bath.

The object of the present invention is to provide a heating container and a household appliance for heating liquids, comprising a cooking vessel under the bottom of which is fixed a heating element, the corresponding part of the bottom of the tank being made of stainless steel, which makes it possible to obtain good regulation performance for the production of frying.

Another object of the present invention is to provide a heating container and a household appliance for heating liquids, comprising a cooking tank under the bottom of which is fixed a heating element, the corresponding part of the bottom of the tank being made of stainless steel. , whose construction is economical.

These objects are achieved with an electrically heated container for a domestic appliance for heating liquids, in particular intended for the production of frying, comprising a tank having a bottom and side walls, made at least partly of stainless steel, a heating element being fixed under a distribution plate made of a material which is a good heat conductor, the distribution plate being fixed under a part made of stainless steel from the bottom of the tank, as well as a temperature control member, owing to the fact that the control member temperature is in thermal contact with a diffusing plate made of a good heat conducting material, fixed on an external face of the tank in said part made of stainless steel, and that the heat exchanges by conduction between the distribution plate and the diffusing plate are made through the tank, and, if necessary, by at least a thermal bridge connecting the distribution plate to the diffusing plate. These arrangements make it possible to obtain a satisfactory image of the liquid temperature for the temperature control member, since the transmission of calories is mainly effected by the thickness of the wall of the tank on which the plate is fixed. diffusing. The diffusing plate can advantageously be made of aluminum. The possible presence of one or more thermal bridges facilitates the distribution of the thermal influence of the oil and of the heating element on the temperature control member.

According to an advantageous characteristic, the diffusing plate is adjacent to the distribution plate, this arrangement making it possible to facilitate the operation of assembling the plates with the bottom of the tank, in particular by brazing. According to a first embodiment, the diffusing plate is arranged in a cutout of the distribution plate.

According to a second embodiment, the diffusing plate is fixed under the bottom of the tank laterally relative to the distribution plate.

According to a third embodiment, the diffusing plate is fixed to one of the side walls of the tank, at least part of the diffusing plate being disposed below a minimum level of filling of the tank.

Advantageously, the heating element is an armored heating element having cold ends and the diffusing plate is arranged near the cold ends. This arrangement makes it possible to limit the direct thermal influence of the heating element.

Advantageously, the thickness of the diffusing plate is greater than the thickness of the wall of the tank on which said diffusing plate is fixed. This arrangement makes it possible to better drain the calories from the tank.

According to one embodiment, a mounting member for the temperature control member is fixed to the diffusing plate. As an alternative, the temperature control member can be fixed to the diffusing plate, for example by gluing for a temperature sensor, or be brought into thermal contact with said diffusing plate.

These objects are also achieved with a domestic appliance for heating liquids intended for the production of frying, comprising a housing receiving an electrically heated container associated with temperature control means, the electrically heated container having the aforementioned characteristics.

The invention will be better understood from the study of exemplary embodiments, taken without any limitation being implied, and illustrated in the appended figures, in which: FIG. 1 is a perspective view of an exemplary embodiment of a container heater of a fryer according to the invention, FIG. 2 is a vertical section of the tank shown in FIG. 1, FIG. 3 is a view of the electrical diagram of an apparatus comprising a heating container according to FIGS. 1 and 2, FIG. 4 is a first variant of the exemplary embodiment presented in FIGS. 1 and 2, - FIG. 5 is a second variant of the embodiment presented in Figures 1 and 2, Figure 6 is a bottom view of a third embodiment, Figure 7 is a partial sectional view along a vertical section of the embodiment shown in Figure 6.

Figures 1 and 2 show an electrically heated container 1 belonging to an apparatus such as a fryer. The container 1 comprises a tank 2 made of stainless steel, having side walls 3 and a bottom 4. The tank 2 is preferably obtained by stamping. A distribution plate 5 made of a material which is a good heat conductor is fixed under the bottom 4. The connection between the distribution plate 5 and the external face of the bottom 4 can in particular be obtained by brazing, by welding, or by hot stamping. . An armored heating element 6 is fixed under the distribution plate 5. The connection between the heating element 6 and the distribution plate 5 can in particular be obtained by brazing, by welding, or by hot stamping. The heating element 6 is fixed at the edge of the distribution plate 5. The heating element 6 has two cold ends 7 provided with connection terminals 8. A rod 9 is provided in the center of the bottom of the tank 2 for fixing to the device housing (not shown in the figures). The rod 9 is fixed to the distribution plate 5.

A mounting member 10 of a temperature control member is fixed to the outside of the tank 2 in an area not covered by the plate 5. The control member, not shown in FIGS. 1 and 2, can be a regulating member such as a bimetallic thermostat with fixed or adjustable set temperature.

As shown in Figures 1 and 2, the mounting member 10 is a rod fixed to a diffusing plate 11 fixed under the bottom 4 of the tank in a cutout the distribution plate 5. The thicknesses of the diffusing plate 11 and of the distribution plate 5 are identical, for example of the order of 3 mm. The thickness of the bottom 4 is less than that of the distribution plate, and is for example of the order of 1 mm.

The connection between the diffusing plate 11 and the external face of the bottom 4 can in particular be obtained by brazing, by welding, or by hot stamping. The diffusing plate 11 and the distribution plate 5 can come from the same part and be cut before assembly with the tank 2. The diffusing plate 11 and the distribution plate 5 can also come from the same assembled part with the tank 2, an annular groove 12 being produced after assembly with the tank 2. The width of the groove 12 between the diffusing plate 11 and the distribution plate 5 is preferably between one and three times the depth of said throat. As shown in Figure 2, the width of the groove 12 is twice the depth of said groove. The mounting member 10 is preferably fixed near the cold ends 7 of the heating element 6, that is to say in an area less sensitive to direct radiation from the heating element 6.

Figure 3 shows the electrical circuit of the apparatus comprising the container 1. A control light 13 is mounted in parallel with the heating element 6. A temperature control member 14, provided for regulating the temperature of the bath liquid, is mounted in series with the heating element 6. A safety device 15 such as a thermal fuse is also mounted in series with the heating element 6.

The present exemplary embodiment operates in the following manner.

When the heating element 6 heats the tank 2 containing a liquid, in particular oil or any other fat suitable for frying, the calories of the heating element 6 are first transmitted to the distribution plate 5 and then to the oil through the bottom 4 of the tank 2. The temperature of the temperature control member 14 mounted on the mounting member 10 is influenced by thermal radiation, produced essentially by the heating element 6 and the distribution plate 5, by the thermal conduction of the air, for a very small part, and by the thermal conduction of the diffusing plate 11. The temperature of the diffusing plate 11 is influenced by the radiation thermal, produced essentially by the heating element 6 and the distribution plate 5, by the thermal conduction of air, for a very small part, and by the thermal conduction of the bottom 4 of the tank 2. The mounting member 10 being fixed in an area not directly sensitive to the radiation of the heating element, the thermal radiation is weak compared to the conduction. The calories from the bottom 4 mainly come from the oil, and not directly from the distribution plate 5, due to the low thermal conductivity of the stainless steel of the distribution plate 5. The temperature control member 14 in thermal contact with the diffusing plate 11 via the mounting member 10 can thus present a thermal image of the temperature of the oil present in the tank 2. After the first cut of the control member of temperature 14, the high thermal conductivity of the diffusing plate 11 makes it possible to follow the evolution of the temperature of the tank 2 containing the oil bath. The temperature of the oil bath obtained during successive cuts in the regulating member is thus very close to the temperature of the oil bath during the first cut. This arrangement makes it possible to obtain a good quality of cooking fries with immersion of the fries in the oil bath from the first cut of the temperature control member 14.

FIG. 4 shows an alternative embodiment differing from the previous embodiment in that a diffusing plate 21 is fixed to the external face of the bottom 4 'of the tank 2' laterally with respect to a distribution plate 25 supporting a heating element 26.

The diffusing plate 21 and the distribution plate 25 are adjacent. A groove 22 is formed between the diffusing plate 21 and the distribution plate 25. The diffusing plate 21 is also arranged near the cold ends 27 of the heating element 26. The operation of this exemplary embodiment is close to that of the previous example. FIG. 5 shows an alternative embodiment differing from the previous exemplary embodiments in that a diffusing plate 31 is fixed on the external face of the side walls 3 "of the tank 2" near the cold ends 37 of the heating element 36 .

In this exemplary embodiment, the tank is preferably parallelepipedal so as to simplify the fixing of the diffusing plate 21. The diffusing plate 31 and the distribution plate 35 are adjacent. The diffusing plate 31 is arranged so that at least part of said plate is located below a minimum level 38 of filling of the tank. The lower end of the diffusing plate 31 provides a groove 32 with the periphery of a distribution plate 35 under which a heating element 36 is fixed. Preferably the groove 32 corresponds to the radius of the tank 2 "connecting the bottom 4" to the side walls 3 ". The operation of this exemplary embodiment is close to that of the preceding exemplary embodiments.

Figures 6 and 7 show another alternative embodiment in which a diffusing plate 41 is connected to a distribution plate 45 by thermal bridges 48, 48 '.

The diffusing plate 41 is formed in a cutout of the distribution plate 45. Annular groove portions 42 separate the diffusing plate 41 from the distribution plate 45. As best seen in FIG. 6, the thermal bridges 48, 48 ′ are arranged diametrically opposite with respect to the diffusing plate 41. Each thermal bridge 48, 48 ′ is arranged equidistant from the cold ends 47 of a heating element 46 fixed under the distribution plate 45. As best visible in FIG. 7, the thickness of the thermal bridge 48 disposed at the periphery of the distribution plate 45 corresponds to the thickness of the diffusing plate 41 or of the distribution plate 45, while the thickness of the thermal bridge 48 'is less.

The thermal bridges 48, 48 'make it easier to fix the plate diffusing and the distribution plate 45 under the bottom 4 "" of the tank 2 "", without significantly affecting the operation of the temperature control member. A thermal bridge has a reduced section compared to the section of the distribution plate and the diffusing plate. The section, the number of thermal bridges and their arrangement can be adapted to the power of the heating element 46 and to the geometry of the tank of the distribution plate, of the heating element and of the diffusing plate. The presence of thermal bridges between the distribution plate 45 and the diffusing plate 41 also makes it possible to facilitate regulation in the event of dry heating. A single thermal bridge can be provided between the distribution plate and the diffusing plate.

Many variations and / or improvements can be made to this electrically heated regulated container within the scope of the claims.

In particular, the bottom of the tank is not necessarily flat and / or horizontal, and the thickness of the tank can be variable. Part, if not all, of the side walls of the tank may be made of a material other than stainless steel. Part of the bottom of the tank can also be made of a material other than stainless steel. The distribution plate is then fixed on a stainless steel part of the bottom of the tank. The diffusing plate is then fixed on the stainless steel part of the bottom of the tank or on an extension of said part belonging to a side wall of the tank. In the latter case, at least part of the diffusing plate is arranged below a minimum level of filling of the tank.

The geometries of the diffusing plate and the distribution plate, their material (s), their relative arrangement can be adapted to the geometry of the tank and to the geometry and the power of the heating element, to obtain a good thermal image of the oil bath.

The thermal bridges between the distribution plate and the diffusing plate can also be envisaged for the other alternative embodiments.

The thermal bridges between the distribution plate and the diffusing plate can be formed by inserts. The temperature control device may in particular be a bimetallic thermostat with a fixed or variable set temperature, or even a temperature sensor associated with a microcontroller.

The temperature control member can be attached to the diffusing plate directly or through a mounting member. The control member can also be kept in contact directly against the diffusing plate or by using an intermediate contact piece. Such a part can for example be a cover covering the control member mounted in a housing of the device, the diffusing plate coming to bear on the contact part.

As a further variant, a safety member such as a thermal fuse can be fixed to a diffusing plate, directly or by means of a mounting member, or else can be kept in contact directly against the diffusing plate or using an intermediate contact piece. The diffusing plate can also receive a regulating member or be independent of the diffusing plate receiving the regulating member.

The present invention finds its application in an electrical device intended for carrying out cooking in an oil bath such as a fryer.

Claims

1. Electrically heated container for household appliance for heating liquids, in particular intended for making fried foods, comprising a tank (2; 2 '; 2 "; 2'") having a bottom (4; 4 '; 4 "; 4' ") and side walls (3; 3 '; 3"; 3' "), made at least partly of stainless steel, a heating element (6; 26; 36; 46) being fixed under a distribution plate (5 ; 25; 35; 45) made of a material which is a good heat conductor, the distribution plate being fixed under a part made of stainless steel from the bottom of the tank, as well as a temperature control member (14), characterized in that the temperature control member (14) is in thermal contact with a diffusing plate (11; 21; 31; 41) made of a material which is a good conductor of heat, fixed to an external face of the tank (2; 2 '; 2 "; 2'") in said part made of stainless steel, and in that the heat exchanges by conduction in be the distribution plate (5; 25; 35; 45) and the diffusing plate (11; 21; 31; 41) are made via the tank (2; 2 '; 2 "; 2'"), and, if necessary, by at least one thermal bridge (48, 48 ') connecting the distribution plate (45) to the diffusing plate (41).

2. An electrically heated container according to claim 1, characterized in that the diffusing plate (11; 21; 31; 41) is adjacent to the distribution plate (5; 25; 35; 45).

3. Electrically heated container according to one of claims 1 or 2, characterized in that the diffusing plate (11) is arranged in a cutout of the distribution plate (5).

4. Electrically heated container according to one of claims 1 or 2, characterized in that the diffusing plate (21) is fixed under the bottom (4 ') of the tank (2') laterally relative to the distribution plate ( 25).

5. An electrically heated container according to claim 1, characterized in that the diffusing plate (31) is fixed to a side wall (3 ") of the tank (2"), at least part of the diffusing plate being disposed below. a minimum level (38) of filling the tank (2 ").

6. Electrically heated container according to one of claims 1 to 5, characterized in that the heating element (6; 26; 36; 46) is an armored heating element having cold ends (7; 27; 37; 47) and in that the diffusing plate (11; 21; 31; 41) is arranged near the cold ends (7; 27; 37; 47).

7. Electrically heated container according to one of claims 1 to 6, characterized in that the thickness of the diffusing plate (11; 21; 31; 41) is greater than the thickness of the wall of the tank (2; 2 '; 2 "; 2'") on which said diffusing plate is fixed.

8. Electrically heated container according to one of claims 1 to 7, characterized in that a mounting member (10; 10 '; 10 "; 10'") of the temperature control member (14) is fixed on the diffusing plate (11; 21; 31; 41).

9. Household appliance for heating liquids intended for the production of frying, comprising a housing receiving an electrically heated container associated with temperature control means, characterized in that the electrically heated container conforms to one of claims 1 to 8.