EP0022879B1 - Dish washer - Google Patents

Abstract

1. A dish-washing machine, in particular for domestic use, in which a flow pipe (6) carrying a stream of washing fluid during the washing operation is coaxially disposed within a further flow pipe (12) wherein the flow pipe (12) is provided with a coaxial tubular heater (11), so that an air stream for drying the dishes, flowing through the annular space between both flow pipes (6, 12), is heated, characterized in that the flow pipes (6, 12) and the tubular heater (11) are disposed below the bottom of the container (1) receiving the dishes, in such manner that the tubular heater (11) is located within the annular space, carrying the air stream, between both flow pipes (6, 12) and also heats the flow pipe (6) carrying the stream of washing fluid.

Description

The invention relates to a dishwasher, in particular for domestic use, in which a vertical flow tube through which the washing liquid flows during the rinsing process is arranged coaxially in a further flow tube, a tube heating element being coaxially assigned to this flow tube, so that the flow through the annular space between the two flow tubes airflow serving to dry the dishes is heated.

From US-A-3 023 757 a dishwasher with two axially arranged and vertically standing flow tubes and a tubular heater coaxially assigned to these through tubes has become known. The tubular heater is arranged in the dirty water sump of the dishwasher. The flushing liquid heated by the tubular heating element is sucked off through an opening arranged at the lowest point of the dirty water sump and fed to a rotatable distributor for the flushing liquid via a vertical pipe. During the drying process, fresh air is blown onto the tubular heating element via an annular space arranged concentrically to the tube and an air duct, and is heated by the latter.

The disadvantage of this embodiment is the arrangement of the tubular heating element in the dirty water sump and the direct contact of the tubular heating element with the dirty water liquid.

The invention is based on the object of developing a known dishwasher of the type in question in such a way that the tubular heater heats both the washing liquid in the passage and the air flow, in a space-saving arrangement below and outside the receiving space for the dishes.

The arrangement of an electrical heating device for heating the dry air in dishwashers outside and below the container holding the dishes is known in principle from US Pat. No. 3,130,737. With this heating device, however, only the air flow can be heated, but not the washing liquid.

The solution to the above problem arises from the characterizing features of the new main claim. The dependent on claims 2 to 4 describe preferred embodiments.

• Fig. 1 schematisch eine Schnittansicht einer bevorzugten Ausführungsform einer Geschirrspülmaschine;
• Fig. 2 in vergrößertem Maßstab eine Schnittansicht des Bodenteiles der Geschirrspülmaschine.

In the drawings, a preferred embodiment of the subject of the invention is shown. Show it:

• 1 schematically shows a sectional view of a preferred embodiment of a dishwasher;
• Fig. 2 is an enlarged sectional view of the bottom part of the dishwasher.

A dishwasher usually has a container 1 with generally extendable baskets 2 which serve to hold the dishes 3. A collecting sump 4 serves to collect the outflowing rinsing liquid, which is fed from a pump 5 via a flow pipe 6 to a lower distributor arm 7 and an upper distributor arm 8. The distributor arms 7 and 8 are attached to a pipe section 9.

Three tubular heating elements 11 are arranged on the continuous tube 6, namely the tubular heating elements 11 are helically bent around the continuous tube 6. Furthermore, a flow tube 12 is provided, which has a larger diameter than the flow tube 6 and which is arranged concentrically to the axis of the flow tube 6 and the spiral axis of the tubular heating element 11. An air line 13 is connected to the flow tube 12, so that air sucked in by a blower 14 is driven through the annular channel formed by the flow tube 6 and the flow tube 12 during the drying process.

The arrangement 7, 8, 9 is rotatably mounted in the upper ends of the flow tubes 6 and 12. The lower distributor arm 7 is divided in two by means of a partition 15. The lower region of the distributor arm 7 communicates with the annular space between the flow tubes 6 and 12, so that the air drawn in by the blower 14 and passing over the tubular heating element 11 1 is blown out of the nozzles 16 into the interior of the container 1. The upper part of the distributor arm 7 and the interior of the distributor arm 7 are connected to the interior of the flow tube 6, so that the washing liquid driven by the pump 5 is sprayed onto the dishes via spray nozzles 17.

Rotary bearings 18, which are arranged at the upper ends of the flow tubes 6 and 12, serve for rotatably mounting the rigid arrangement of the tube 9 and the distributor arms. The drive takes place in a known manner by the recoil of the media emerging from the correspondingly inclined nozzles 16 and 17, i.e. of the detergent liquid flow or the heated air flow.

• Die Spülflüssigkeit kommt nicht mit dem Rohrheizkörper 11 in Berührung, so daß Ablagerungen auf denselben und örtliche Überhitzungen vermieden werden. Die Rohrmäntel der Rohrheizkörper 11 brauchen dementsprechend nicht aus teuren Chromnickelstählen zu bestehen, die außerdem noch besonders gegen Spannungsrißkorrosion geschützt werden müssen. Wenn bei bekannten Ausbildungen ein Rohrheizkörper einer Spannungsrißkorrosion unterliegt, dann besteht die Gefahr, daß die Spülflüssigkeit in den Rohrheizkörper eindringt und dementsprechend die Maschine unter Spannung gesetzt wird. Eine derartige Möglichkeit ist bei der neuartigen Ausbildung ausgeschlossen, so daß auch entsprechende Sicherheitsvorkehrungen entfallen können. Die Rohrheizkörper 11 sind weiterhin durch das Durchlaufrohr 12 geschützt. Der Behälter 1 kann dementsprechend auch aus Kunststoff gefertigt werden, da keine Gefahr besteht, daß durch Strahlungshitze oder durch Absprühen von flüssigem Metall bei Überhitzung eines Rohrheizkörpers das Kunststoffgehäuse in Brand gerät. Weiterhin ist der Wärmeübergang sowohl auf den Spülflüssigkeitsstrom als auch auf den Luftstrom äußerst günstig, so daß eine entsprechende Energieeinsparung erzielt wird. Da die Rohrheizkörper 11 in Form einer Wendel auf das Durchlaufrohr 6 aufgebracht sind, wird der Luftstrom gedreht und entsprechend verwirbelt. Der Energiebedarf während des Trockenvorganges ist dementsprechend gering, so daß es genügt, wenn für den Trockenvorgang die Rohrheizkörper 11 in Serie geschaltet werden. Während des Aufheizvorganges der Spülflüssigkeit werden die Rohrheizkörper 11 parallel geschaltet, so daß sich eine möglichst kurze Aufheizzeit ergibt. Diese Parallelschaltung kann während des Spülvorganges beibehalten werden. Es kann jedoch dann auch einer der Rohrheizkörper 11 abgeschaltet oder in Serie dazugeschaltet werden.

The new training now has a number of advantages:

• The flushing liquid does not come into contact with the tubular heating element 11, so that deposits on the same and local overheating are avoided. Accordingly, the pipe jackets of the tubular heating element 11 do not have to be made of expensive chromium-nickel steels, which are also particularly suitable Stress corrosion cracking must be protected. If, in known designs, a tubular heating element is subject to stress corrosion cracking, there is a risk that the flushing liquid will penetrate into the tubular heating element and the machine will accordingly be energized. Such a possibility is excluded in the new type of training, so that corresponding safety precautions can also be dispensed with. The tubular heater 11 are still protected by the flow tube 12. Accordingly, the container 1 can also be made of plastic, since there is no danger that the plastic housing will catch fire due to radiant heat or spraying of liquid metal when a tubular heating element overheats. Furthermore, the heat transfer to both the flushing liquid stream and the air stream is extremely favorable, so that a corresponding energy saving is achieved. Since the tubular heating elements 11 are applied to the flow tube 6 in the form of a spiral, the air flow is rotated and swirled accordingly. The energy requirement during the drying process is accordingly low, so that it is sufficient if the tubular heating elements 11 are connected in series for the drying process. During the heating process of the rinsing liquid, the tubular heating elements 11 are connected in parallel, so that the heating time is as short as possible. This parallel connection can be maintained during the rinsing process. However, one of the tubular heating elements 11 can then also be switched off or connected in series.

The coaxial vertical arrangement of the flow tube 6, the tubular heater 11 and the flow tube 12 in the lower part of the dishwasher has proven particularly useful, since in this way an unimpeded guidance of the media flows and easy storage and interchangeability of the arrangement from the distributor arms is achieved with a relatively small space requirement .

Instead of the tubular heater 11, other heating devices can also be provided. Thus, the flow tube 6 can also be formed by a die-cast part that has helical grooves on its outside for receiving heating coils and insulating material.

Claims (4)

1. A dish-washing machine, in particular for domestic use, in which a flow pipe (6) carrying a stream of washing fluid during the washing operation is coaxially disposed within a further flow pipe (12) wherein the flow pipe (12) is provided with a coaxial tubular heater (11), so that an air stream for drying the dishes, flowing through the annular space between both flow pipes (6, 12), is heated, characterized in that the flow pipes (6, 12) and the tubular heater (11) are disposed below the bottom of the container (1) receiving the dishes, in such manner that the tubular heater (11) is located within the annular space, carrying the air stream, between both flow pipes (6, 12) and also heats the flow pipe (6) carrying the stream of washing fluid.

2. A dish-washing machine according to claim 1, characterized in that a plurality of helically arranged tubular heaters (11) are disposed within the annular space between the flow pipe (6) carrying the stream of washing fluid and the flow pipe (12) forming the outer pipe, and that the tubular heaters (11) are connected in parallel during the washing operation, whilst the tubular heaters are connected in series during the drying operation and heat the drying air streaming through the annular space between the flow pipe (6) and the outer pipe (12), said dry air being blown onto the dishes through at least one distributor arm (7).

3. A dish-washing machine according to claims 1 or 2, characterized in that the outer pipe (12) forms a rotary bearing (18) for the distributor arms (7, 8).

4. A dish-washing machine according to claims 1 to 3, characterized in that the lower distributor arm (7) is divided into two separate regions by a partition wall (15), wherein the upper region communicates with the flow pipe (6) for the washing fluid and includes suitable spray nozzles (17) for the washing fluid, whilst the lower region communicates with the annular space between the flow pipe (6) and the outer pipe (12) and is provided with air nozzles (16).

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