Filtering unit for dishwasher

Abstract: A filtering unit for dishwasher is described which comprises a first wide mesh filter (2) arranged on the bottom of a washing tank (3) of said dishwasher so as to collect and to filter the washing water contained in said tank (3), a second narrow mesh filter (6) arranged around the first filter (2) in order to carry out an additional filtering of said washing water, a tray (7) for the collection of the filtered washing water. Between the first filter (2) and the second filter (6) a third intermediate mesh filter (4) is arranged in order to carry out another filtering of the washing water before this reaches the second filter (6).

Description: The present invention refers to a filtering unit for dishwasher. Generally there are known dishwashers that are provided with a filtering unit for the washing water which is arranged on the bottom zone of the washing tank of the dishwasher. Such filtering unit is usually made up of a tray for the collection of the washing water that is provided with a filter container and with a pierced bucket arranged inside the filter container. The washing water flows at first through the bucket where it undergoes a rough filtering action and then through the filter container where it undergoes a finer filtering action by means of the small size holes of the filter container; finally the filtered washing water is collected by the tray. A filtering unit of the type described can also be self-cleaning, that is provided also with means that provide to the cleaning of the filter container. A problem in which often filtering units of the type described incur resides in the premature clogging of the filter container because of a multiplicity of debris or filaments that are carried by the washing water which manage to pass through the holes of the bucket. DE 3 507 229 discloses a dishwasher provided with a filtering unit as described in the preamble of claim 1. In view of the state of the art herein described, scope of the present invention is to provide a filtering unit for dishwasher that solves. the aforementioned problem. According to the present invention, such scope is reached by means of a filtering unit for dishwasher as defined in claim 1. Owing to the present invention it is possible to provide a filtering unit for dishwasher which by means of an additional filter prevents the premature clogging of the filter container. The characteristics and the advantages of the present invention will become evident from the following detailed description of an embodiment thereof, that is illustrated as a non-limiting example in the enclosed drawings, in which: Figure 1 is a schematic view of the filtering unit for dishwasher according to the present invention; Figure 2 is a top view of the single device for the cleaning of the filters. With reference to Figure 1 filtering unit 1 of a dishwasher machine not visible entirely in Figure is shown. The filtering unit 1 comprises a first filter made up of a bucket 2, which is defined in claim 1 as first wide mesh filter, provided with passages areas for the flow of water and arranged in the bottom part of a washing tank 3 of the dishwasher machine, so as to collect all the water contained in the tank 3 in order to carry out a first filtering of the same in a rough way due to the wideness of the passage areas of the bucket 2. Externally to the bucket 2 and around it a second cylindrical filter 4, which is defined in claim 1 as third intermediate mesh filter, is arranged that is provided with passage areas for the flow of water smaller than those of the bucket 2 so as to carry out a second filtering operation of the washing water. The filter 4 has a hole 5 on the bottom for the passage of water jets that are suitable to the cleaning of the filter 4. Externally to the second filter 4 and around it a third filter made up of a filter container 6, which is defined in claim 1 as second narrow mesh filter, is arranged that is provided with passage areas for the flow of water even smaller than those of the second filter 4 so as to carry out a third filtering operation of the washing water. The filter container 6 is arranged inside of a tray 7 that is suitable to collect the filtered washing water. The filters 2, 4, 6 allow to carry out an operation of gradual filtering of the washing water, which goes from a rough type filtering operated by the bucket 2 to a finer filtering operated by the filter container 6. On the bottom of the filter container 6 a device 8 for the cleaning of the filters 4 and 6, better visible in Figure 2, is placed. Said device 8 comprises a round ring 9 provided with a multiplicity of nozzles 10 with a circumferential symmetry, and a central nozzle 11 connected with the ring 9 by means of an appendix 12. On the bottom such device 8 is connected with a tube 13 where the clean water flows at a certain pressure such as to allow the outflow of the water jet of a certain size from the central nozzle 11 for cleaning the cylindrical filter 4 through the hole 5 and from the nozzles 10 for cleaning the filter container 6. The hole 5 of the intermediate filter 4 has a diameter smaller than the internal diameter of the round ring 9 of the device 8; in that way during the cleaning of the filters the dirty water can fall directly on the bottom of the tray 7 in order to be then discharged to the outside by means of an appropriate discharge pump not visible in the Figures. The appendix 12 comprises a watertight closed-loop duct for the flow of the clean water coming from the tube 13 toward the nozzles 10.

Claims: Filtering unit for dishwasher comprising a first wide mesh filter (2) arranged on the bottom of a washing tank (3) of said dishwasher so as to collect and to filter the washing water contained in said tank (3), a second narrow mesh filter (6) arranged around the first filter (2) in order to carry out an additional filtering of said washing water, a tray (7) for the collection of the filtered washing water, between said first filter (2) and said second filter (6) a third intermediate mesh filter (4) being arranged in order to carry out another filtering of the washing water before this reaches said second filter (6), characterised in that it comprises a device (8) for the cleaning, with clean water, of the second (6) and third (4) filters arranged on the bottom of the second filter (6). Unit according to claim 1, characterised in that said device (8) comprises a multiplicity of circumferential nozzles (10) for the output of water jets suitable to clean the second filter (6) and a central nozzle (11) for the output of water jets suitable to clean the third filter (4). Unit according to claim 2, characterised in that said third filter (4) is provided with a hole (5) on the bottom and said circumferential nozzles (10) of said device (8) are arranged in a round ring (9) having an internal diameter greater than the diameter of the hole of said third filter (4) so that during the cleaning of the same the dirty water falls directly on the bottom of the tray (7).

Inventors: FUMAGALLI SILVANO, FUMAGALLI, SILVANO
Applicants: CANDY SPA, CANDY S.P.A.
Application year: 2001
Main classification: A47L15
IPC codes: A47L15