GB2271417A

GB2271417A - Foil thermal transmission wall in containers in an appliance operable with water

Info

Publication number: GB2271417A
Application number: GB9320298A
Authority: GB
Inventors: Ernst Stickel; Ulrich Deiss; Ruediger Eiermann; Hans Mailaender; Helmut Jerg
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-10-06
Filing date: 1993-10-01
Publication date: 1994-04-13
Anticipated expiration: 2013-10-01
Also published as: DE4233643A1; FR2696333A1; GB9320298D0; FR2696333B1; ITMI932080A0; ITMI932080A1; IT1272707B; DE4233643C2; GB2271417B; TR27284A

Abstract

An appliance operable with water comprises a principal container (1) for heated liquid and a storage container (10) connected in thermally conductive manner by means of a foil wall (11) laid or layable against the principal container. The storage container (10) comprises plastics material. The foil can consist of, for example, three layers, such as a layer of aluminium sandwiched between outer layers of polyester and polypropylene respectively closest to and furthest from the principal container. <IMAGE>

Description

- 1 2271417 THERMAL TRANSMISSION BETWEEN CONTAINERS IN AN APPLIANCE

OPERABLE WITH WATER The present invention relates to an appliance operable with water, and has particular reference to thermal transmission between containers in such an appliance.

Water-conducting domestic appliances with thermally conductive connection between a principal container and a storage container are known from, for example DE-OS 27 30 489 and DE-OS 30 21 746. Such storage containers are used for the storage of liquids required for phases of the program of a program-controlled appliance. The thermally conductive connection with the principal container has taken the form in the state of the art as a wall of sheet metal placed against the container DE-05 30 21 746. The container itself consists of sheet metal, in particular stainless steel, and constitutes the working container in, for example, a dishwashing machine or a laundry washing machine. The container walls are is provided with stiffening ribs, corrugations or grooves, which may run in all directions and intersect, extending across the walls and matched to the geometric shape of the containers. The difficulty therefore results of matching the storage container wall to the varying shapes of principal container wall. This difficulty leads to substantial cost in production of storage containers and to a plurality of storage container types. It has proved that notwithstanding specific matching of shapes a complete overall contact of the respective container walls is, due to tolerances, possible in only a few cases. Unless complete overall contact is achieved, air is included between the two walls and acts as thermal insulation buffer, which substantially reduces heat transfer from the principal container wall to liquid situated in the storage container.

For the avoidance of the efore-mentioned disadvantages, there is know from DE-GM 17 04 904 an appliance with a storage container, which is connected in thermally conductive manner to a principal container for heated liquid, the rear wall of the container being constructed as a hollow body which forms the storage container. The partition wall between the principal container and the storage container is made of relatively thin, thermally conductive sheet metal. In practice, it has proved that in spite of the use of thin is sheet metal the heat transfer is still not optimal, due to the thickness of the container wall and to heat radiation. Moreover, it is commonplace to introduce liquids, which can possibly be admixed with chemicals, into such storage containers, for example in domestic dishwashing machines. In particular, brine is flushed out of an ion exchanger of a water-softening unit after regeneration and is conducted into the storage container. Even with the use of stainless steel, the possibility of corrosion of the storage container walls is quite high in the known arrangement.

There is therefore a need for an appliance in which the heat transfer from the container wall to liquid in the storage container may be improved in simple manner and in which corrosion by liquids, which are mixed with chemicals and introduced into the storage container may be avoided.

-.5 - According to the present invention there is provided an appliance operable with water and comprising a first container for heated liquid and a second container comprising plastics material and thermally conductively connected or connectible to the first container by means of a foil wall laid or layable against the first container.

With use of a foil wall, which is substantially thinner than a sheet metal wall, it may be possible in simple manner to achieve a substantial improvement of the heat transfer. A foil can, by reason of its small thickness, adapt itself completely to all constructions of the container wall against which it is laid or to be laid, so that formation of an air cushion with thermally insulating effect can be avoided. By virtue of the contact capability of a foil, the manufacture. of diverse storage container types is unnecessary.

Through use of synthetic material, in particular plastics material, for the entire second, i.e. storage container, corrosion of the storage container is avoided and the use of the storage container for liquids containing chemicals is possible. The heat transfer of synthetic material, which is generally poorer by comparison with sheet metal, is more than compensated for by the very small thickness of the foil, and heat radiation from the remaining walls of the storage container is prevented, so that an insulation layer around the storage container is not needed. The contacting behaviour of synthetic material foils is further improved by heating of the liquid in the first container and thereby also of the container walls, since synthetic materials become softer at corresponding temperatures.

According to a preferred feature, the foil wall is mounted to be sagging loosely at the remaining walls of the second container.

Through the loose mounting of the foil, the contacting behaviour of the foil is substanti al ly improved at all protrusions and depressions of the wall of the first container.

In particularly advantageous construction, the foil wall is welded to the remaining walls of the second container. A simplification of the manufacture of the second container is thereby achieved.

Expediently, the remaining walls of the second container are made of polypropylene, since polypropylene is a synthetic material with a high resistance to chemicals.

In a preferred embodiment the foil wall comprises a compound foil, thus has at least two layers which can possibly consist of different materials. Through the use of a compound foil the conflicting requirements in respect of strength, heat transfer and resistance to chemicals may be satisfied.

Advantageously, the compound foil comprises at least three layers so that the layer which is to lie against the first container can contribute to the best possible contact and to the strength of the compound foil, and the layer which is directed towards the interior of the second container can be designed for the best possible connection with the remaining walls of the second container, for the best possible heat transfer to the liquid disposed in the second container and for the best possible resistance to chemicals. The or each intermediate layer can additionally be designed for contribution to heat transfer and to strength.

These advantages are advantageously improved if the outer layers of the compound foil comprise synthetic material.

In order to prevent diffusion of moisture from the second container through the synthetic material layers to between the foil and the wall of the first container, the or at least one intermediate layer of the compound foil can be made of a material preventing diffusion. The need for corrosion protection at the first container may thereby be avoided.

In order to also do justice to the requirements for good heat transfer and good strength, the or at least one intermediate layer of the compound foil expediently comprises aluminium foil.

Aluminium foil has a good heat transfer co-efficient and is at least as good as a synthetic material foil layer with respect to contact behaviour at the wall of the first container. Moreover, the strength of the compound foil is further increased by the use of aluminium foil.

In order to simplify the connection of the foil to the remaining walls of the second container, the layer arranged towards the interior of the second container advantageously comprises polypropylene.

Expediently, the layer facing the first container comprises polyester, since polyester is a synthetic material with an adequate stability of shape even at relatively high temperatures such as arise during the connecting or welding to the remaining walls of the second container and the layer arranged towards the interior of the second container, so that the outer layer of the compound foil is not damaged by the welding. Polyester also has a very high strength, whereby a further contribution to thestrength requirements of the compound foil is made.

According to a further advantageous embodiment, the foil wall of the second container is a single-layer foil and the wall of the' first container which faces the second container is coated. Through the use of a single-layer foil wall at the second container, a saving in production costs of the second container is achieved. By coating the first container, the risk of corrosion through moisture penetrating between the container wall and the second container is avoided.

Preferably, the coating has the form of a foil, whereby a further simplification, in particular in manufacture, may be achieved.. In the case of possible recycling of the first container, a foil can be removed more easily than some other forms of coatings.

Preferably, the coating foil is a compound foil, which can comprise at least two layers possibly of different materials.

Through the use of a compound foil, the requirements of strength and heat transfer can be met in advantageous manner. In order to avoid diffusion of moisture through the foil, one layer of the compound foil can comprise a material preventing diffusion. In order to provide a good heat transfer and also a good strength, the material can be aluminium foil. As already mentioned, aluminium has a good heat transfer co-efficient and is at least as good as synthetic material in terms of contacting behaviour at the first container wall.

Expediently, the layer, which faces the first container, of the coating foil comprises polyester, in view of the capability of polyester to maintain an adequate stability of shape at the relatively high temperatures which can occur at the container walls in appliances operating with water. Polyester also contributes additional strength to the coating foil.

In one preferred embodiment, the remaining walls of the second container are solid walls. This allows simple mounting of the second container on the first container as well as simple manufacture of the second container.

However, in another embodiment the entire second container consists of foil. This embodiment is distinguished by particularly low costs of material and production. In order to avoid undesired deformation of such a second container, it can be arranged in a support frame. By this measure, it is avoided in particular that, due to the inevitable bulging out of the walls on filling of liquid into an unsupported foil bag, the foil wall lying against the first container is lifted off the first container wali over large areas.

Moreover, the strength of the entire second container is increased in simple mode and manner by such a support frame.

Expediently, the support frame is fastened to the first container, whereby a simple assembly of the entire arrangement can be achieved.

Advantageously, connecting stub pipes are welded to the foil.

For preference, the foil or foils arranged between the first container and the liquid in the second container has or in totality have a thickness of substantially 0.2 millimetres or less.

Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a schematic sectional view of part of' a wall of a principal container of a first water conducting domestic appliance embodying the invention and a storage container mounted -on that wall; Fig. 2 is the detail II of Fig. 1 to an enlarged scale; Fig. 3 is a schematic sectional view of part of a wall of a principal container of a second water conducting domestic appliance embodying the invention and a storage -container, mounted on that wall; Fig. 4 is the detail IV of Fig. 3 to an enlarged scale; Fig. 5 is a perspective view of a third water conducting domestic appliance embodying the invention, with a side panel removed to show a storage container mounted on a principal container of the appliance; Fig. 6 is a schematic sectional view of part of the wall of the principal container. and of the storage container, of the appliance of Fig. 5; and Fig. 7 is the detail VII of Fig. 6 to an enlarged scale.

Referring now to the drawings there is shown part of a domestic appliance which is operable with water and comprises a working or principal container 1, 11 or V' for heated liquid.

Connected therewith in thermally conductive manner by means of a wall 11, 111 or 111', which is laid or layable against a wall 2, 21 or V' of the principal container, is a storage container 10, 101 or 1W for a further liquid. The wall 11, 111 or W' of the storage container consists of a foil. The foil is connected to the remaining walls 15, 151 or W' of the storage container to sag loosely. The wall 2, 21 or V' of the principal container has reinforcing corrugations, in the form of protrusions and depressions, which are not described more closely.

In a first preferred embodiment, shown in Figs. 1 and 2, the wall 11, which lies against the principal container 1, of the storage container 10 is a compound foil 11 with three layers, wherein the outer layers are formed by plastics material foils. The outer layer 12, which faces the container 1, is made of polyester and the inner layer 13, which faces towards the interior of the storage container 10. is made of polypropylene. The intermediate layer 14 is formed by an intermediate foil 14, which is a material preventing diffusion.

The remaining walls 15 of the storage container 10 are structured to be solid and consist of polypropylene. The trough, open at one side, formed by the solid walls 15 has a rim 16, which runs round the open side and extends outwardly of the storage container 10 and which is tightly welded to the inner layer 13 of the compound foil 11.

In a further embodiment as shown in Figs. 3 and 4, the wall ill, which lies against the container V, of the s.torage container 101 consists of a single-layer foil 11' of polypropylene. The wall V, which lies opposite the storage container 101, of the container 11 is coated, in particular with a two-layer compound foil 3', one layer 14' of which is aluminium foil 141 and the other layer 121 of which, facing the container 11, is a polyester foil 1P.

The remaining walls 151 -of the storage container 101 are soli.d and consist of polypropylene, as for the embodiment of Figs. 1 and 2. The trough, open at one side, formed by the solid walls 1.51 is equipped with a rim 161, which runs round the open side and extends outwardly of the storage container 101 and which is tightly welded to the polypropylene foil 1V.

In a further advantageous embodiment of the water -conduct i ng domestic appliance 511, as shown in Figs. 5, 6 and 7, the entire storage container 1011 consists of a one-layer polypropylene foil Connecting nipples 17, of which only one is shown, are welded to the foil 1511.

The wall V', which lies opposite the storage container 1011, of the container 111 is coated, in particular, and as for the embodiment of Figs. 3 and 4, with a two-layer compound foil Y', one layer 1411 of which is an aluminium foil W' and the other layer 12" of which, facing the container 11', is a polyester foil 12". The storage container 1011 is arranged in a support frame 611, which isfastened to the container 111.

In all embodiments, the foil or foils 11 or 111, 31 or 1111, 315, which is or are arranged between the principal container and liquid in the storage container, has or in totality have a thickness of 0.2 millimetres.

In use of the appliance, for example a domestic dishwashing machine 51' as shown in Fig. 5, the storage container is filled with cold liquid during or at the beginning of a program phase, while liquid in the principal container, a rinsing container 1 in the case of the dishwashing machine P, is heated. Due to the contact of the foil wall 11, 111 or W' of the storage container with the wall 2, 21 and 211 of the principal container heat is transferred from the principal container wall, which is heated by the liquid in the principal container, to the liquid in the storage container. Thus, the liquid. withdrawn from the.storage container in a subsequent program phase requiring use of heated liquid can be heated to the required temperature with substantially lower consumption of heating energy.

Moreover, in the case of the afore-mentioned dishwashing machine 511, the storage container is filled with cold liquid in a program phase in which a condensation effect of arising liquid vapour is desired,, so that the wall 2, 21 or 211 of the principal container is cooled and the desired condensation effect occurs in the interior of the container at this wall.

Furthermore, in the case of a domestic dishwashing machine with a water-softening unit, on the regenerationof an ion exchanger of the unit.the brine, which is expressed out of this and/or which arises during flushing can be stored in the storage container until it can be let out into the principal container without disturbing the program sequence and conveyed out of this.

Claims

1. An appliance operable with water and comprising a first container for heated liquid and a second container comprising plastics material and thermally conductively connected or connectible to the first container by means of a foil wall laid or layable against the first container.

2. An appliance as claimed in claim 1, wherein the foil wall is so dimensioned as to be able to freely sag in an unfilled state of the second container..

3. An appliance as claimed in claim 1 or claim 2, wherein the foil wall is welded to further walls of the second container.

4. An appliance as claimed in any one of the preceding claims, wherein the second container, apart from the foil wall thereof, is made of polypropylene.

5. An appliance as claimed in any one of the preceding claims, is wherein the foil wall has a plurality of layers.

6. An appliance as clained in claim 5, wherein the foil wall has at least three layers.

7. An appliance as claimed in claim 6, wherein the outer layers comprise plastics material.

8. An appliance as claimed in claim 6 or claim 7, wherein the or at least one inner layer comprises a material resistant to diffusion of liquid through the foil wall.

9. An appliance as claimed in claim 8, wherein the or at least one inner layer comprises aluminium.

10. An appliance as claimed in any one of claims 5 to 9, wherein the foil wall layer further or furthest from the first container comprises polypropylene.

11. An appliance as claimed in any one of claims 5 to 10, wherein the foil wall layer closer or closest to the first container comprises polyester.

12. An appliance as claimed in any one of claims 1 to 4, wherein the foil wall consists of a single-layer material and the first container is provided with a coating on a side wall thereof facing the foil wall.

13. An appliance as claimed in claim 12, wherein the coating is provided by a foil.

14. An appliance as claimed in claim 13, wherein the foil comprises plastics material.

15. An appliance as claimed in claim 13 or claim 14, wherein the foil comprises a plurality of layers.

16. An appliance as claimed in claim 15, wherein one of the layers comprises a material resistantto diffusion of liquid through the foil.

17. An appliance as claimed in claim 16, wherein said one layer comprises aluminium.

18. An appliance as claimed in any one of claims 15 to 17, wherein the foil layer closer or closest to the side wall comprises polyester.

19. An appliance as claimed in any one of the preceding claims, wherein the second container is defined by, in addition to the foil wall, substantially rigid walls. -

20. An appliance as claimed in any one of claims 1 to 18, wherein the second container is made entirely of foil.

21. An appliance as claimed in claim 20, wherein the second container is arranged in a support frame.

22. An appliance as claimed in claim 21, wherein the frame 'is attached to the first container.

23. An appliance as claimed in any one of claims 20 to 22, wherein the second container -comprises duct connecting means welded to the constituent foil of the second container.

24. An appliance as claimed in any one of claims 1 to 11, wherein the foil wall has a thickness of at most substantially 0.2 10 millimetres.

25. An appliance as claimed in any one of claims 12 to 18, wherein the foil wall and the coating together have a thickness of at most substantially 0.2 millimetres.

26. An appliance as claimed in any one of claims 19 to 23, wherein 15 the foil wall has or the foil waIl and the coating together have, as the case may be, a thickness of at most substantially 0.2 millimetres.

27. An appliance substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings.

28. An appliance substantially as hereinbefore described with reference to Figs. 3 and 4 of the accompanying drawings.

29. An appliance substantially as hereinbefore described with reference to Figs. 5 to 7 of the accompanying drawings.