GB2187931A

GB2187931A - Inner container for electrically heated water boilers

Info

Publication number: GB2187931A
Application number: GB08705201A
Authority: GB
Inventors: Hilmar Stephan
Original assignee: Rowenta Werke GmbH
Current assignee: Rowenta Werke GmbH
Priority date: 1986-03-06
Filing date: 1987-03-05
Publication date: 1987-09-23
Also published as: DE3607290A1; GB2187931B; GB8705201D0; DE3607290C2

Abstract

An electrically heated water boiler comprises a chamber for receiving water to be boiled, a heating element 15 for boiling the water and arranged to be switched off by a steam-operated switch 12 in communication with steam in the chamber, an inner container 2 for receiving a food or drink product to be heated, the inner container having an outer wall 8 having ribs 16 arranged to be exposed to steam in the chamber, and the chamber having an opening 5 to atmosphere the size of which is variable so as to vary the amount of steam allowed to escape from the chamber. This variable opening enables the final temperature of the heated product to be controlled. <IMAGE>

Description

SPECIFICATION Inner container for electrically heated water boilers The invention relates to an inner container for an electrically heated water boiler.

Inner containers for electrical water boilers in the handle of which an automatic steamoperated cutoff switch is incorporated are already known. The contents of these containers are heated by immersing the container in a bath of water. The final temperature of the heated product in the container is approximately the same as the temperature of the water bath, which means that these inner containers have few advantages apart from preventing the heated product from burning. Furthermore, the energy consumption is extremely high since a large quantity of water has to be heated in the boiler each time.

Viewed from one aspect the invention provides an inner container for an electrically heated water boiler, in the handle of which there is an automatic steam-operated cutoff switch, wherein the outer diameter of the inner container is less than the inner diameter of the water boiler, the inner container having a flange which projects over the edge of the water boiler and which has an opening the cross section of which can be varied by a closure, and the height of the inner container being substantially less than the height of the water boiler.

Viewed from another aspect the invention provides an electrically heated water boiler comprising a chamber for receiving water to be boiled, a heat source for boiling the water and arranged to be switched off by a steamoperated switch in communication with steam in the chamber, an inner container for receiving a food or drink product to be heated, the inner container having an outer wall arranged to be exposed to steam in the chamber, and the chamber having an opening to atmosphere the size of which is variable so as to vary the amount of steam allowed to escape from the chamber.

By varying the amount of steam or water vapour allowed to escape from the water boiler, the heating time before the heat source is switched off by the steam-operated switch is varied, thereby enabling the final temperature of the heated product to be predetermined.

In a preferred embodiment, the outer wall of the inner container defines a cavity the other boundary surfaces of which are formed by the inner wall of the water boiler and the surface of the water put in. When the water is heated it changes from the liquid state into the vapour state. The vapour rises and condenses on the outer wall of the inner container, releasing the heat of condensation to the inner container and the product to be heated contained therein. As the temperature of the heated product rises, less steam condenses on the outer. wall of the inner container and there is then a greater quantity of steam in the cavity. The automatic cutoff switch in the water boiler is designed so that when a certain quantity of steam is reached in the cavity the heating of the water boiler is switched off.

The quantity of steam in the cavity is controlled by means of the opening which is connected to atmosphere. The cross section of the opening is variable. If an opening with a larger cross section is used, more steam escapes through the opening and it takes longer for the automatic cutoff switch to operate. If an opening with a smaller cross section is used, less steam escapes and the automatic cutoff switch is actuated faster. As a result, the final temperature of the heated product is higher when the opening has a large cross section than when the opening has a smaller cross section. The final temperature of the heated product is continuously variable by altering the cross section of opening.

Preferably the inner container is centred in the water boiler by means of ribs, so that the annular space between the inner wall of the water boiler and the outer casing of the inner container is made uniform. If the ribs are provided on the outer wall of the inner container the surface area of the outer wall is increased so as to increase the area for condensation of steam. However, the same effect can also be achieved by similar measures to increase the surface area.

In a preferred embodiment, the cross section of a steam inlet opening to the automatic steamoperated cutoff switch is variable. This can ensure that the uncondensed quantity of steam is prevented from acting on the automatic cutoff switch until the desired final temperature of the heated product is reached. The inventive arrangement of a bimetal e.g. a bimetallic strip can effectively aid this process.

Markings may be provided on the flange or on the lid of the water boiler to make it easier to select the required final temperature for the heated product.

Certain preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 shows an electric water boiler together with an inner container according to the invention in section; Figure 2 shows another embodiment of the invention; and Figure 3 shows a plan view of the inner container as shown in Figure 2; Figure 4 shows another embodiment.

In the electrically heated water boiler 1 with inner container 2 inserted therein as shown in Figure 1, a flange formed on the inner container projects over the upper edge 4 of the water boiler 1. The flange 3 has an opening 5. In the region of this opening 5, a rotary closure 6 with a bore 7 is provided on the flange 3. In order to heat up food and drinks in the inner container 2, water is introduced into the water boiler 1 up to the level indicated, the inner container 2 is inserted in the water boiler 1 and the desired final temperature of the contents is preselected using the rotary closure 6. The water is brought to the boil by switching on a heating element 15 for the water boiler 1. The steam produced condenses on the outer wall 8 of the inner container 2 and heats up the product to be heated contained therein.As the temperature of the heated product rises, less steam condenses on the outer wall 8. As a result, the quantity of steam increases in the cavity 9 which is formed between the outer wall 8 of the inner container 2, the inner wall 10 of the water boiler 1 and the surface 11 of the water put in. The automatic steam operated cutoff switch 12 in the handle 13 of the water boiler 1 is connected to the cavity 9 via the opening 14 and adjusted so that when there is a certain quantity of steam in the cavity 3 the heating element 15 is switched off.

The cavity 9 communicates with atmosphere through the opening 5 in the flange 3. The cross section of the opening 5 is continuously variable by means of the rotary closure 6.

This enables the quantity of steam in the cavity 9 to be controlled. If the opening 5 has a large cross section more steam escapes from the cavity 9 into the open atmosphere than if the opening 5 had a small section and consequently, if the cross section is larger, it takes longer for the automatic cutoff switch 12 to switch off the heating element 15. The final temperature of the heated product in the inner container 2 is thus controlled by varying the cross section of the opening 5 using the rotary closure 6.

Ribs 16 are provided on the outer wall 8 of the inner container 2, to centre the inner container 2 inside the water boiler 1 and increase the area for condensation of the steam.

In the embodiment of the invention shown in Figures 2 and 3, the cross sections of the opening 5 in the flange 3 of the inner container 2 and of the opening 14, between the cavity 9 and the automatic steam-operated cutoff switch 12, can be varied by means of a slide 17. As shown in Figure 3, a handle 22 is provided on the inner container 2 and the slide 17 is mounted on the flange 3. Markings 18 are provided on the flange 3 in the region of the slide 17, to enable preselection of the desired final temperature of the product to be heated in the inner container 2. It is also possible to control the slide 17 by means of a bimetal (not shown).

In the embodiment of the water boiler 1 shown in Figure 4, there is an opening 20 in the lid 19 of the water boiler 1, the cross section of which can be varied by means of a rotatable closure 21. The closure 21 is rotatably mounted on the lid 19 and provided with an opening 23.

In the embodiments by way of example shown in Figures 2 and 4, the final temperature of the contents of the inner container 2 is also controlled by means of the quantity of steam in the cavity 9, as in the embodiment shown in Figure 1.

Modifications to the invention both in its broad aspects and in its preferred embodiments may be apparent to a person skilled in the art and it is intended that such modifications are included in the scope of this disclosure.

Claims

1. An inner container for an electrically heated water boiler, in the handle of which there is an automatic steam-operated cutoff switch, wherein the outer diameter of the inner container is less than the inner diameter of the water boiler, the inner container having a flange which projects over the edge of the water boiler and which has an opening the cross section of which can be varied by a closure, and the height of the inner container being substantially less than the height of the water boiler.

2. An inner container as claimed in claim 1, wherein the cross section of the opening can be varied by means of a slide provided on the flange and markings are provided on the flange in the region of the slide.

3. An inner container as claimed in claim 1, in combination with a water boiler having an automatic steam-operated cutoff switch in its handle, wherein a lid of the water boiler has an opening, a closure being rotatably mounted on the lid, and the closure being provided with an opening.

4. An inner container as claimed in claim 1,2 or 3, in combination with a water boiler having an automatic steam-operated cutoff switch in its handle, wherein a steam inlet opening of the cutoff switch is of variable cross-section.

5. An inner container as claimed in any of claims 1 to 4, wherein a bimetal is arranged to actuate the closure of the opening.

6. An inner container as claimed in any of claims 1 to 5, wherein ribs are provided on the outer wall of the inner container.

7. An electrically heated water boiler comprising a chamber for receiving water to be boiled, a heat source for boiling the water and arranged to be switched off by a steam-operated switch in communication with steam in the chamber, an inner container for receiving a food or drink product to be heated, the inner container having an outer wall arranged to be exposed to steam in the chamber, and the chamber having an opening to atmosphere the size of which is variable so as to vary the amount of steam allowed to escape from the chamber.

8. An inner container for an electrically heated water boiler substantially as hereinbe fore described with reference to Figure 1 or Figures 2 and 3 or Figure 4 of the accom panying drawings.

9. An electrically heated water boiler substantially as hereinbefore described with reference to Figure 1 or Figures 2 and 3 or Figure 4 of the accompanying drawings.