WO1988004532A1

WO1988004532A1 - Kettle for heating a liquid in ''bain-marie''

Info

Publication number: WO1988004532A1
Application number: PCT/IT1987/000101
Authority: WO
Inventors: Claudio Jacovacci
Original assignee: Claudio Jacovacci
Priority date: 1986-12-23
Filing date: 1987-12-16
Publication date: 1988-06-30

Abstract

A kettle for heating a liquid in bain-marie, said kettle consisting of a first cylindrical can (2) in which a second cylindrical can (4) is inserted, both cans being sealingly connected along their upper edges, thus forming a cylindrical cavity (6) of constant thickness between the vertical walls of the two cans and a plane cavity (8) between the bottoms of the same. Such cavity has a capacity of about a quarter of the capacity of the inner can and communicates with the outside by a valve (14) located in the handle (10, 12) screwed to the kettle. The cavity is filled with water through said valve so that the inner can is essentially in bain-marie within the outer can.

Description

Kettle for heating a liquid in "bain-marie".

DESCRIPTION

This invention relates to a kettle provided with a cavity wall in which an amount of water is contained. Before milk can come to the boil, all water in the cavity wall has to vaporize, thus allowing a stay time 5 of the kettle on the hot plate much longer than that usually taken by the milk to boil over. A safety valve provided in the handle of the kettle allows the cavity wall to be filled with water and the steam to escape when water comes to the boil.

10 Housewives know very well how much it is dangerous to leave the milk kettle or milk-jug on the hot plate. When milk reaches the boiling temperature, level of milk rises quickly and milk-froth boils over with the danger for the housewife of putting out fire without her

15 knowing it.

In order to prevent such trouble different solutions have been suggested such as covers provided with particular holes, cavities entered by milk, baffles and other tricks to break the upper surface of the boiling

20 milk with the result of making the kettles expensive and not suitable for being readily used.

, This invention seeks to solve the above mentioned problem by providing a cheap kettle which is - outwardly not different from the conventional kettles and

25 uses a cookinc method well known to the skilled in the cookery, such as cooking in bain-marie.

To this end the kettle consists of a first can of aluminum inserted into a second can, both cans being sealingly connected to each other along their upper edges, thus forming a cavity wall having a capacity of about a quarter of the inner can. The- cavity communicates with the outside by a safety valve located in the handle of the kettle which is screwed to the outer can. Such cavity is filled with water -through said valve so that the inner can is in bain-marie within the outer can.

As the boiling temperature of the milk is a little higher than that of the water, it will be reached only when all water contained in the cavity is vaporized, the steam leaving the cavity through the above mentioned valve. Therefore, milk does not reach its boiling temperature in the right time, but according to tests its temperature does not exceed 80°C even after a staying time of 30 minutes on the hot plate.

A spring-loaded safety valve located in the handle of the kettle closes the entrance bore to the cavity between cans and partially opens only when water contained in the cavity starts boiling. The sealing action is assured by a spiral spring keeping the valve, e.g. a ball valve, adherent to its seat, i.e. the entrance bore. Such sealing action is sufficient to establish, under atmospheric conditions a pressure a little higher than .the vapor pressure of the water, but lower than the vapor pressure of the milk, thus allowing the steam to leave the cavity through said valve. The spiral spring is anchored on one side to the ball valve and on the other side to the opposite wall of the cavity remote from the entrance bore.

Accorάincr to a preferred embodiment of the invention the safety valve is provided with an arm which is hinged at a distance from the . entrance bore and around which a spiral spring is wound. The valve has a conical seat so that the cross section of the entrance bore gradually decreases to the inside. When the arm of the valve is rotated so that .the valve is under closed condition, the valve remains closed as long as the outer pressure is lower than the inner pressure. When the arm of the valve is rotated by an angle, e.g. 90° to the seat of the valve, the entrance bore is open and the cavity can be filled with water.

This is an advantage in case of washing the kettle.

In such a case the valve is brought in its seat, thus avoiding any inlet of water contaminated by ^•a cleansing agent into the cavity, even if ^' an outside pressure is exerted on the valve body. On the other hand, when the valve is rotated, e.g. by 90° from the closed position, the cavity may be rinsed and or filled with water.

This invention will be described in detail with reference to the annexed drawing in which a preferred non-limitative embodiment thereof is shown. Fig. 1 is a cross section of an elevation view of the kettle;

Fig. 2 is a cross section along the line II-II of Fig. 1 illustrating the input valve; and

Fig. 3 is a cross section along the line II-II of Fig. 1 illustrating a second embodiment of the input valve. Referring to the figures, the kettle in bain-marie consists of a first cylindrical can 2 of aluminum in which a second cylindrical can 4 of pure aluminum is inserted. The upper edges 2 ' of both cans 2 and 4 are sealed to each other, thus -forming a vertical ."cylindrical cavity 6 of constant thickness along the vertical walls of both cans and a horizontal cavity 8 between the bottoms of the same. Cavity 6, 8 is tight except for the connection to valve 14 as described herebelow.

The diameter of inner cylindrical can 4 is equal to the diameter of outer cylindrical can 2 along the upper edge 2 ' thereof where both cans are sealed to each other-. Inner cylindrical can 4 extends outwardly from the connection edges of both cans with a lip 4' used to pour the liquid of the inner can 4.

A handle of plastic material is connected to the outer can of the kettle at a height little lower than the upper edge thereof. Such handle consists of a first hollow horizontal length 10 connecting an opening 16 in the wall of the outer cylindrical can 2 through a channel 20 to a horizontal bore 22 perpendicular to channel 20. Bore 22 is the seat of a ball valve 14 which is spring-loaded by a spiral spring 24 anchored to the opposite wall of channel 20 remote from the bore 22. Thus, ball valve 24 establishes the connection of cavity 6, 8 between cans 2, 4 to the outside. After the first horizontal length 10 of the handle a second length 12 of massive plastic material is provided, said second length extending downwardly about up to the bottom of the kettle and forming an angle of about 25° to the vertical. Such slope permits the hand of the user to grasp this second length and to handle the kettle in particular when it is necessary to fill the cavity between both cans with water.

A second embodiment of the spring-loaded safety valve is shown in Fiσ. 3. Entrance bore 28 provided in the handle 12 is closed by a poppet valve 30 which is kept adherent to bore 28 by a spiral spring 32 wound around an arm 34 hinged on handle 12 at a distance from bore 28. Spring 32 is adjusted so as to allow valve 30 to be opened when the vapor pressure of the water in cavity 6, 8 is still lower than the vapor pressure of the milk. Since the boiling temperature of water under the same pressure conditions is lower than the boiling temperature of milk, water continues boiling up to its complete vaporization before milk starts boiling.

In operation, the empty kettle is either put horizontally under a water-spout or immersed in a water bath, the kettle being held hanging from the handle and the valve being under opened conditions so that the cavity can be filled till water appears at the entrance bore. Afterwards the kettle is put in the vertical position and the inner can is filled with the liquid to be heated without its exceeding the boiling temperature of water. This temperature will be reached and exceeded only after all water contained in the cavity is vaporized, the steam leaving the cavity through the valve.

As the capacity of the cavity is equal to about a quarter of the capacity of the inner can; the time necessary to the complete vaporization of the water contained in the inner can is considerable and in any case is warned of the water vaporization by the steam leaving the kettle through the valve.

Claims

1. Kettle for heating in bain-marie a liquid having a boiling temperature higher than that of water under the same atmospheric conditions, characterized in that it consists of a first can inserted into a second can, both cans being sealingly connected along their upper edges, thus forming a cavity wall around the inner can having a capacity of about a quarter of the capacity of said inner can, said cavity communicating with the outside through a valve located in the handle of the kettle which is screwed to the outer can at a height little lower than the upper edge thereof.

2. The kettle for heating in bain-marie of claim 1, wherein the kettle is provided with a handle having a first horizontal length in which an inner channel communicating with said cavity between inner and outer cans is provided, said channel having an outlet consisting of a conical bore closed by a ball valve which is loaded by a spiral spring connected between the ball valve and the opposite wall of the channel remote from the conical bore, and a second vertical length extending downwards about up to the bottom of the kettle and forming an angle of about 25° with the vertical .

3. The kettle for heating in bain-marie of preceding claims, wherein said valve located in the horizontal length of the handle is a poppet valve provided with an arm which is hinged at a distance from the entrance bore and around which a spiral spring is wound, said spring being adjusted so as to exert on the valve a pressure lower than the vapor pressure of the liαuid to be heated in bain-marie.

4. The kettle for heating in bain-marie of claim 1, wherein said second vertical length of the handle is of thermo-inεulating material.

5. The kettle for heating in bain-marie of claim

1, wherein the inner can is of pure aluminum.

6. The kettle for heating in bain-marie of claims 1 and 2, wherein said conical bore has a cross section gradually decreasing to the inside.

7. Kettle for heating in bain-marie essentially as described and illustrated in the annexed drawing.