WO1989009010A1 - Household steam-cooking appliance - Google Patents

Abstract

Said household appliance for steam-cooking of food has a steam production chamber (1), a cooking chamber (2) linked to the former and means (7) to extract the liquid particles suspended in the steam flow. It can be used as a household appliance for the steam-cooking of one or several individual portions.

Description

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Home steam cooking appliance

The present invention relates to a domestic appliance for cooking food with steam. There are two main kinds of household appliances for cooking food with steam: cooking appliances at a pressure substantially equal to atmospheric pressure and cooking appliances at a pressure well above this pressure. The advantage of these is that they require very little steam to cook. On the other hand, they have a double disadvantage, namely, requiring a construction which must take account of the fact that, precisely, the cooking takes place at a pressure distinctly higher than atmospheric pressure, which not only imposes corresponding mechanical qualities, but also safety devices, and only ensure poor cooking in terms of dietetics, in particular because the vitamins do not support it and because the cooking water is most of the time too concentrated to be usable . Compared to these devices, devices for steaming at atmospheric pressure have the double advantage of respecting the vitamins in food and of requiring neither particular mechanical qualities of construction nor safety devices. On the other hand, they require a large quantity of steam and therefore an equally large consumption of calories.

Furthermore, designed for family needs and therefore for cooking several portions, all these devices are not economically suitable for cooking individual portions and the reason is that their miniaturization is not a simple problem of homothety.

The object of the present invention is to remedy these drawbacks by proposing an appliance for cooking food with steam which retains the advantages of the two known types of appliance, namely simplicity of construction, no need for safety devices, cooking respecting food and low consumption of liquid. Furthermore, its design allows

FIRE use it indifferently when cooking one or more individual portions.

Such a cooking appliance essentially comprises a steam production chamber, and a cooking chamber connected to the first chamber and in which the steam produced is distributed and it is characterized in that means are arranged on the path of the steam between production chamber and cooking chamber for extracting from said vapor all the liquid droplets which are suspended therein, so as to distribute only pure steam in the cooking chamber.

Thanks to this arrangement which makes it possible to use the entire volume of steam produced, it becomes possible to cook food with a limited quantity of liquid and without obtaining, however, at the end of cooking, a liquid that is too concentrated. According to another essential characteristic of the invention, means are provided for bringing back into the vapor production chamber, at least part of the liquid extracted from the vapor stream.

In a preferred embodiment of the invention, the steam outlet from the steam production chamber takes place in the upper part of said chamber, through at least one orifice of dimension restricted at least in its height and whose orientation is such that the jet of steam which leaves it is directed on a wall of an annex chamber which is less hot than the steam production chamber.

Thanks to this double arrangement, the droplets of liquid which could be in suspension are fixed on the wall, as are the vapor particles which are at a temperature below a certain value. Furthermore, the dimensions of the annex chamber are such that they provide a relaxation which cancels the consequences, on the outgoing steam current, of the venturi effect caused by the outlet orifice (s) of steam outlet, beneficial effect otherwise necessary to obtain the separation of the liquid droplets and the vapor on said wall.

According to an interesting characteristic of the previous embodiment, the annex room has such a connection with the steam production chamber that the condensed steam returns to this chamber.

According to another characteristic, the annex chamber also serves as a liquid reserve for the steam production chamber so that the mass of liquid which the latter contains can be transformed into vapor more quickly and more regularly than if all this mass s' was there.

Furthermore, the steam which condenses in the annex chamber will transmit to the reserve of liquid which it joins, the calories which it had received in the steam production chamber, thus ensuring preheating of this reserve.

In a preferred embodiment of a steam generator fitted to a steam cooking appliance according to the invention, the heating of the water for the formation of steam takes place from the bottom of the production chamber of steam, this bottom producing a succession of cavities in which the water is brought more quickly to the boiling temperature than with a flat heating bottom.

According to another preferred embodiment, the surface of the heating bottom of the steam production chamber is advantageously chosen to be rough so as to promote the regular formation of small bubbles of steam, avoid boiling by jolts with bubbling as well as local overheating of the water likely to disturb the proper functioning of the device, and thus add to the regularity ^" of steam production.

Other characteristics and advantages of the invention will appear during the description which follows, with reference to the accompanying drawings which illustrate several examples, given purely by way of non-limiting indication, of embodiment of the present invention.

Figure 1 is a sectional elevation of a cooking appliance according to the invention.

FIG. 2 is a section on a reduced scale, along the lines II-II of FIG. 1.

FIG. 3 is a section on a reduced scale along the lines III-III of FIG. 2. FIG. 4 is a view, also on a reduced scale, along arrow IV of FIG. 1.

Figure 5 is a sectional elevation of another steam generator for a cooking appliance according to the invention. FIG. 6 is an exterior view of a cooking appliance according to the invention, for cooking individual portions, with a device for grinding cooked food, in the cooking chamber.

Figures 7, 8 and 9 show a cooking chamber according to the invention in which one or more portions can be cooked.

Figure 10 shows another alternative embodiment of the invention.

The appliance illustrated in FIGS. 1 to 4 consists of a steam generator L and a container 2.

The generator 1 is formed by a housing 3, a removable cover 4 and an armored electrical resistance 5 arranged in the bottom of the housing 3.

The outer surface of the shield is slightly rough and the arrangement of the entire resistor is such that it constitutes a series of parallel cavities 21 (see FIGS. 2 and 3).

The case 3 has the shape of a rectangular parallelepiped, of square section, with an internal shoulder 12 which extends all along its four sides, the upper edge of each side having, in its middle, a bayonet slot 13.

The removable lid 4 is square and its dimensions correspond to those of ^f shoulder 12 on which it rests. It comprises, firstly, a slight central cone crossed by a passage 6, secondly, a circular wall 7 concentric to the passage 6 and extending inside the housing 3 and, thirdly, a chamber 8 also concentric to passage 6 and of substantially cylindrical shape.

The chamber 8 has at its upper part, that is to say at its junction with the cover 4, three thin slots 9 arranged at 120 ° from one another. Its bottom 10 is slightly conical, the tip at the bottom, and has an orifice 11 at this tip.

REPLACEMENT SHEET The container 2, cylindrical, is closed by a cover 15, and its vertical wall 14 has, at its lower part, four pins 16 arranged at 90 ° from each other. Its bottom 17 carries, in its central part, a tube 18, which rests on the central cone of the removable cover 4 of the housing 3 by means of an O-ring 22 which seals between the tube and the central cone. The tubing 18, the section of which is slightly increasing in its upper part, comprises several slots 19 and it is closed at its end 20, the total section of the slots being equal to two and a half times the interior section of the tubing 18 at the where said slots 19 begin.

Under these conditions, the operation is established as described below.

The whole apparatus being disassembled, the quantity of water required is poured into the housing 3.

The cover 4 is then placed on the housing 3, resting on the shoulder 12, then the container 2 on the joint 22, and finally, the four lugs 16 of the container 2 are engaged in the bayonet slots 13 of the housing 3 to secure all. Finally, the vegetables to be cooked are placed in the container 2, possibly cut into cubes if they are too large and, after having placed the cover 15 on the said container 2, the appliance is connected.

The temperature rises in the electrical resistance 5, and its shield begins to transmit the calories it receives to the water with which it is in contact. It is the water which is in the cavities 21 which will go up in temperature more quickly, since it is heated on two sides at the same time. The slight roughness of the shielding surface will favor, on the one hand, the exchange of calories by the larger contact surface that it offers compared to a smooth surface, and on the other hand, boiling by facilitating , firstly, the formation of air bubbles, then secondly, their detachment.

The bubbles that detach, rise to the surface of the water where they burst, increasing the pressure in the gas space above the water.

TO REPLACE ΛEN. * When the pressure reaches a certain value, the air-steam mixture, then, as the water boils, the steam alone, pass into the chamber 8 through the three thin slots 9, which cause an effect venturi, so that the 5. steam arrives in the chamber 8 in the form of three laminar jets projected against the circular wall 7 which is at a temperature markedly lower than the temperature of the steam jets which it receives.

Thanks to this arrangement, the water droplets which would have been entrained by the vapor, as well as the particles of vapor below a certain temperature condense on the wall 7, and the water thus condensed flows along the said wall, falls on the bottom 10 of the chamber 8 and is recycled through the orifice 11 which returns it to the body of water being heated in the housing 3. Furthermore, the dimensions of the chamber 8 are such that the vapor undergoes an expansion there so that it is at a slow speed that it will pass through the passage 6 and the pipe 18.

Since this passage and this tubing are also at a temperature below the temperature of the vapor, there may be a second condensation on their internal walls, and the water thus condensed will flow along these walls, to fall back on the bottom 10 of the chamber 8 and return, through the orifice 11, to the body of water being heated.

This second condensation further slows down the speed of the vapor stream and means that the vapor stream can no longer cause water droplets.

The pressure and the rate of arrival of the steam on the food to be cooked will be further reduced by the section of the tubing 18 which is increasing and by the section of the slots 19 which is equal to two and a half times that of the tubing 18 where they start.

These vegetables are also at a temperature much lower than the temperature of the vapor, there will be a new condensation. But under the conditions in which it occurs, it will be a slight condensation which will provide three advantageous results. First of all, vegetables do not have to undergo the brutal thermal shock of the instant arrival of a large

SHEET THIS REPLACEMENT amount of steam. Secondly, there is wetting of the vegetables with water condensed from a steam identical to the steam which will ensure its cooking and with which the exchange will be thus favored. Finally, the condensed water being hot, the cooking process will start immediately.

Gradually, the circular wall 7, then the tubing 18 will rise in temperature and the condensations will decrease, so that the vapor current will become progressively more abundant, the water droplets entrained by the vapor through the slots 9 of the chamber 8 still being stopped on the circular wall 7.

At the end of a certain time, a sort of equilibrium is established on all the vapor path and one arrives practically in the state known as "saturated vapor" where the vapor reaches its maximum pressure which will remain as long as water will remain at sufficient temperature.

Usually, common vegetables cut into cubes of about 10 mm edge will be cooked after 10 to 20 minutes, depending on the vegetables, if they are subjected to the effects of saturated steam. When they are cooked, the appliance is disconnected and they are easily removed from the cooking container 2 which is removable.

FIG. 5 shows an alternative embodiment of a steam generator having certain advantages compared to that of FIGS. 1 to 4. This generator comprises a steam production chamber 23 and a water reserve chamber 24 separate from the first by a partition 27 comprising a series of small diameter orifices 28 at its upper part and a slot 29 at its lower part.

The chamber 23 is equipped with an electrical resistance 25 similar to the resistance 5 of FIGS. 1 to 4, that is to say constituting parallel cavities. In the upper part, a grid 26 is arranged. Finally, there is an orifice 33 closed by a plug 34.

The chamber 24 has an inclined bottom 30. Its horizontal upper wall 36 carries a drop 31 parallel to the partition 27, and a tube 32 which passes through the bottom of a cooking chamber 35 only primed in the drawing.

REPLACEMENT SHEET The operation of this generator is similar to the operation of the generator in Figures 1 to 5.

Through the orifice 33, the required quantity of water is poured which is distributed, thanks to the slot 29 located at the bottom of the partition 27, between the chamber 23 for producing steam and the water reserve chamber 24.

When the resistor 25 is energized, the water located in contact with it is heated. After a certain time, vapor bubbles form and rise to the surface of the water where they burst, the grid 26 having the function of stopping the water droplets resulting from this burst. The vapor released fills the space above the water level in the chamber 23, on either side of the grid 26, and after a certain increase in pressure escapes through the orifices 28 in the form of jets which strike the fallout 31. The latter, being colder than the partition 27 and a fortiori, colder than the vapor, produces, on the vapor which it receives, the same effect as the circular wall 7 of FIGS. 1 to 4, that is to say, condenses the water droplets which could be suspended in the vapor and the vapor particles which are not hot enough.

The water thus condensed falls back into the water retained by the chamber 24, while the steam, after expansion in the space located above the water, passes through the tube 32 of the cooking chamber 35 where occurs the second condensation, also with fallout of the water condensed in the water of the chamber 24.

A first advantage of this generator is that the grid 26 constitutes a first barrier to the water droplets which could be entrained by the steam when the bubbles burst. A second advantage is that the mass of water in the steam production chamber is only part of the total mass to be transformed into steam, which makes it possible to produce steam more quickly. We know, in fact, that we do not expect a steam generator to heat a given body of water, but that it produces steam. This is why it is more advantageous to obtain steam by heating at the same time only part of the mass of water to be transformed into steam, which makes it possible to start producing it more quickly and to produce it. then more regularly and therefore longer from the same body of water.

The cooking appliance illustrated in FIG. 6 comprises a steam generator 37 connected to a removable cooking chamber 38 by an external pipe 39 which is continued by a steam distribution pipe 40.

In the cooking chamber 38, there is mounted a rotary grinding device 41 driven by a mechanism contained in a casing 42 which is not described because it is not part of the invention. This casing also carries two switches 43 and 44 for controlling the steam generator and the grinding device.

The presence of this rotary grinding device constitutes the main feature of this cooking appliance compared to the other embodiments described. It makes it possible to grind and mix in situ, that is to say without manipulation, the food cooked in the cooking chamber, which is particularly advantageous in the case where this food is intended for people whose diet requires very hygienic conditions, such as, for example, children or certain patients.

A particular feature of the grinding device chosen is the conical shape of the core carrying the knives, a shape which, in cooperation with the also conical outlet of the pipe 32, gives the distribution of the steam throughout the mass of the vegetables to be cooked. Figures 7, 8 and 9 illustrate an embodiment of a cooking chamber according to the invention capable of being used for variable quantities of food while ensuring sufficient steam circulation to cook variable quantities of food. This cooking chamber 45, with a double wall, has a spherical bottom to properly center the food to be cooked, whatever its quantity, and has an internal shoulder 46.

A steam distribution pipe 47 comes to rest on said shoulder 46 by three arms 48 of which it is integral. The cover of the cooking chamber, not shown, carries a tube 49 which fits onto the tube 47, such an arrangement allowing food to be placed in the cooking when the steam distribution pipe is in place.

As for the operation of this device, it is the same as that of the other devices described. If you want to cook two or four times more food, simply replace the tubing 47, either by the tubing 50 of Figure 8 which has a double steam distribution, or by the tubing 51 of Figure 9 which has a quadruple. It is quite obvious that, in this case, the steam generator must be provided accordingly, in particular as regards the quantities of steam necessary for cooking various quantities of food.

It is understood that one can, without departing from the invention, modify construction details or their arrangement in order to obtain the same results.

Thus, Figure 10 shows an entirely different embodiment from the previous ones.

The drawn apparatus comprises a steam generator 52 and a cooking chamber 53. In addition to the electrical resistance 54, two grids 55 and 56 equip the steam generator, the grid 56 being of finer mesh than the grid 55.

As for the cooking chamber, it comprises an annular chamber 57 provided with orifices 58, and its bottom 59 is also provided with orifices 60.

The operation of this device is the same as that of the devices described above, with the following details: on the one hand, it is the grids 55 and 56 which stop the water droplets which could be in suspension in the vapor produced by the generator 52 and, on the other hand, the steam is distributed in the cooking chamber in a centripetal manner through the orifices 58 of the annular chamber 57.

In FIG. 1, the steam distribution pipe 18 of the figure has identical slots 19. By cons, the tubing 38 of Figure 6, whose end is clearly frustoconical, has none. We could very well either

REPLACEMENT SHEET have irregular slots or replace the slots with holes of this or that shape which would play the same role.

Instead of using electrical resistors as shown in the examples described, the liquid could be boiled by heating it with gas or any other fuel.

To better ensure the circulation of the vapor on the surface of the vegetables, it would be possible to produce a pulsed distribution thereof, for example thanks to the succession, just upstream of the outlet, of a venturi-effect section and a section relaxing effect. The device for grinding and mixing food can be mounted so that it cannot be started until cooking is finished, or, so that it can be started intermittently during the period of end of cooking to accelerate, in some cases, the completion thereof.

Although the examples described all refer to cooking with steam, the present invention is applicable to any other steam ensuring normal cooking of food.

Claims

1 - Domestic appliance for steam cooking essentially comprising a steam production chamber and a cooking chamber connected to the first chamber and in which the steam produced is distributed, characterized in that means (7; 26; 28; 31 ; 55; 56) are arranged on the path of the vapor between the production chamber and the cooking chamber to extract from the said vapor all the liquid droplets which are suspended therein, so as to distribute only pure vapor in the cooking chamber. 2 - Apparatus according to claim 1, characterized in that it comprises means (10; 24) which bring back into the steam production chamber, at least part of the liquid extracted from the gas stream. 3 - Apparatus according to one of claims 1 and 2, characterized in that the steam outlet from the steam production chamber takes place in the upper part of said chamber, by at least one orifice (9; 28) the height of which is of limited size in its height and the orientation of which is such that the jet of steam which leaves it is directed onto a wall (7; 31) of an annex chamber which is less hot than the steam production chamber ” 4 - Apparatus according to claim 3, characterized in that the annex chamber (24) constitutes a water reserve in communication with the steam production chamber. 5 - Apparatus according to one of the preceding claims and ^• comprising a steam production chamber in which the heating is carried out by the bottom, characterized in that it constitutes a series of parallel cavities (21). 6 - Apparatus according to one of the preceding claims wherein the heating is carried out by contact between water and the bottom surface of the heating chamber, characterized in that said contact surface is rough. 7 - Apparatus according to one of the preceding claims, characterized in that it comprises in the steam production chamber, a wall separating the reserve of water to be transformed into REPLACEMENT SHEET steam in two parts (24; 23) of which only one is in contact with the heating surface. 8 - Apparatus according to one of the preceding claims and comprising at least one tube ensuring the distribution of steam in the cooking chamber characterized in that the outlet section of said distribution tube (18; 40; 47; 50; 51 ) is at least twice the cross-section of the tube in its narrowest part. 9 - Apparatus according to claim 8, characterized in that the end of the steam distribution tube in the cooking chamber has longitudinal slots (19). 10 - Domestic appliance for cooking food with steam according to any one of the preceding claims, characterized in that the cooking chamber is equipped with a grinding device (41). REPLACEMENT SHEET