WO2006021510A1

WO2006021510A1 - Self-cleaning filter with filter mesh provided with protection

Info

Publication number: WO2006021510A1
Application number: PCT/EP2005/053930
Authority: WO
Inventors: Valerio Vernocchi
Original assignee: Valerio Vernocchi
Priority date: 2004-08-25
Filing date: 2005-08-10
Publication date: 2006-03-02
Also published as: EP1778382A1; ITMI20041666A1

Abstract

A self-cleaning filter with a permeable support (1 ) on which a filter mesh (2) is disposed, comprising a permeable protective element (3) for protecting the filter mesh (2) and disposed on it such that the filter mesh (2) is interposed between the permeable support (1 ) and the protective element (3).

Description

SELF-CLEANING FILTER WITH FILTER MESH PROVIDED WITH PROTECTION

The present invention relates to a self-cleaning filter in accordance with the preamble of the main claim.

Filters for water or for liquids in general comprise a filter mesh which retains the impurities and has periodically to be cleaned to hence regenerate the filter. In the state of the art there are mainly two types of self-cleaning suction filters, namely those with a projecting cleaning member and those in which the cleaning member is secured at its two ends.

Self-cleaning filters with a projecting cleaning member are formed with a permeable rigid support of cylindrical shape, on the inner surface of which there is fixed a filter mesh which is of metal and hence resistant to abrasion. On the axis of the cylindrical support there is disposed a cleaning member comprising a suction nozzle which comes into contact with the surface of the metal filter mesh to draw off the dirt deposited thereon. By moving the suction nozzle helically, the entire surface of the filter mesh can be covered and cleaned. Self-cleaning filters with the cleaning member secured at its two ends also comprise a permeable cylindrical support with a filter mesh disposed in its interior, however as the cleaning member is secured at its two ends, the suction nozzle is maintained at a predefined precise distance from the surface of the filter mesh and never touches it. Although providing a more effective cleaning action and being constructionally more simple, those suction self-cleaning filters with a cleaning member which comes into contact with the surface to be cleaned present the problem of abrasion or even sucking-in of the filter mesh, which for this reason has to be formed of a suitable material, normally metal. A further problem is that the metal filter mesh welded to the permeable support cannot be replaced, for example to change the mesh aperture dimensions and allow coarser or finer filtration.

An object of the present invention is therefore to provide a filter which overcomes the aforesaid drawbacks. A particular object is to provide a filter which allows the use of non- metal filter meshes and hence not particularly resistant to abrasion and not particularly rigid.

A further object is to provide a filter in which the filter mesh can be easily replaced. Another object is to provide a filter which in addition to the normal self-cleaning filter mesh also comprises a self-cleaning coarse filter mesh. Said objects are attained by a device the inventive characteristics of which are defined in the claims.

The invention will be more apparent from the ensuing detailed description of a preferred embodiment thereof provided by way of non- limiting example and illustrated in the accompanying drawings, in which:

Figure 1 is a partly exploded partially cut-away perspective view of the device of the invention;

Figure 2 is an exploded perspective view of the cleaning member. With reference to Figure 1 , the filter of the invention comprises a cylindrical permeable support 1 , normally of stainless steel construction, with a plurality of through holes in its surface to enable the filtered water or liquid to pass. A tubular filter mesh 2, normally of polyester or nylon, is disposed on the inner surface of the permeable support 1. This filter mesh 2 is slightly longer than the permeable support 1 and emerges from it, being folded at its ends over the permeable support 1 to form the two turn-ups R visible in the figure. On the inner surface of the cylinder formed from the permeable support 1 and the filter mesh 2 there is provided a permeable protective element 3, for example a protective mesh with large apertures and preferably of plastic (for example nylon), the purpose of which is to protect the filter mesh 2 from abrasion caused by contact with the cleaning member 4. The permeable support 1 , the filter mesh 2 and the protective mesh 3 form a cylindrical pack 10 held together by two fixing rings 11 , 12, each presenting two lips 13, 14 and 15, 16 which form a large annular well 17, 18 for receiving and clamping the ends of said cylindrical pack 10.

With reference to Figure 2, it can be seen that the cleaning member 6 comprises a suction tube 5 projectingly supported (in a manner not shown for simplicity) at one end in a rotatable and translatable manner. On the other end of the suction tube 5 there is disposed an elbow connector 6 connected to a secondary tube 7 on which a suction nozzle 8 can slide, separated from the elbow connector 6 by a rubber elastic spacer 9, for example a V-ring, i.e. an elastic gasket performing the double task of urging the suction nozzle 8 against the inner surface of the cylindrical pack 10 and at the same time of preventing deposition of dirt on the secondary tube 7 which would prevent sliding of the suction nozzle 8. The contact surface 20 of the suction nozzle 8 is in contact with the inner surface of the protective mesh 3, and during the cleaning operation undergoes a helical trajectory obtained by combining a rotary and translatory movement, to cover the entire inner surface of the cylindrical pack 10 and draw off the deposited dirt. During operation, the water to be filtered enters the interior of the cylindrical pack 10 through one of the open ends and is forced to move radially outwards, passing through its lateral surface and then through the protective mesh 3, the filter mesh 2 and the permeable support 1 , outside which the filtered water is collected. During the process, the impurities present in the water to be filtered are hence deposited on the filter mesh 2 and partly on the protective mesh 3, which can further act as a coarse filter mesh. During filter cleaning and regeneration, the cleaning member is operated, and commences to suck. By both the effect of the elastic spacer 9 and the effect of the vacuum which forms in proximity to the surface 20, the suction nozzle 8, free to translate on the secondary tube 7, is pressed against the inner surface of the cylindrical pack 10, thereby increasing the suction and hence the cleaning effect. The pressure with which the suction nozzle 8 is pressed against the protective mesh 3 and its sliding movement on the protective mesh 3 cause the protective mesh 3 to move locally relatively to the filter mesh 2 and improve the cleaning action. The presence of the protective mesh 3 prevents damage to the filter mesh 2 even if one or more sand grains infiltrate between the contact surface 20 of the suction nozzle 8 and the filter mesh 2, as these sand grains finish within the apertures of the protective mesh 3 and are therefore not pressed by the suction nozzle 8 against the filter mesh 2. Cleaning is complete when the cleaning member has completely swept the inner surface of the cylindrical pack 10, consequently sucking in all the dirt deposited on the inner surface of the filter mesh 2 and of the protective mesh 3. As the cleaning member is self-centering, the facility of the suction nozzle 8 to translate means that a slightly deformable permeable support can be used which during washing therefore becomes ovalized by the vacuum which forms in proximity to the suction nozzle, to hence improve the cleaning action, or alternatively a not perfectly cylindrical permeable support can be used.

The protective mesh 3 can be formed from a rectangular sheet folded to form a cylinder and inserted into the permeable support 1 , on the inner surface of which the filter mesh 2 has been previously positioned. In this manner the protective mesh 3 with a natural tendency to restore its flat shape exerts a pressure causing the filter mesh 2 to better adhere to the lateral surface of the permeable support 1 and oppose any sucking-in action which could occur during the cleaning of the filter mesh 2.

The same effect can be obtained by using a protective mesh 3 of cylindrical form of outer diameter slightly greater than the inner diameter of the permeable support 1 on which the filter mesh 2 has been positioned, so that there is slight interference between them. The protective mesh 3 is also advantageously formed from threads woven such that where two threads cross, these overlap such that one of them, in passing over the other, is detached slightly from the surface of the filter mesh 2. This is useful to allow easier cleaning of any dirt which may become inserted between the protective mesh 3 and the filter mesh 2. The movement of the cleaning member 4 may also be simply rotary if the end part of the suction nozzle 8 in contact with the inner surface of the cylindrical pack 10 is narrow and is as long as the height of the cylindrical pack 10. Contact of the suction nozzle 8 with the inner surface of the protective mesh 3 causes slight local deformation and hence slight sliding of the protective mesh 3 relative to the filter mesh 2 about the region of contact, so facilitating elimination of any dirt inserted between the protective mesh 3 and the filter mesh 2. The solution described here of a protective mesh 3 which by being positioned on the filter mesh 2 protects it from abrasion by the cleaning member can be used not only by self-cleaning filters with a projecting cleaning member, but also by self-cleaning filters with their cleaning member secured at its two ends if the cleaning member can touch or arrive very close to the filter mesh, so being able to suck it in or otherwise damage it by solid bodies, such as sand grains or dirt, becoming interposed between the cleaning member and the filter mesh.

The protective mesh 3 can have a mesh aperture of adequate size (e.g. substantially between 1 and 2 mm) to also provide coarse filtering action, i.e. as a filter mesh able to retain the coarser dirt. A coarse filter mesh is normally present upstream of the cylindrical pack 10, to retain the coarser dirt, but with the defect of not being self-cleaning. In the present manner, however, a self-cleaning coarse filter mesh is achieved.

By virtue of the presence of the protective mesh 3, which performs a protective action for the filter mesh 2, this latter does not need to have particular strength characteristics. This fact means that non-metallic filter meshes can be used, typically of nylon or polyester.

Again, by virtue of the particular conformation of the cylindrical pack 10, the filter mesh 2 alone can be quickly replaced while continuing to use the permeable support 1 , so reducing the cost and time involved in replacing the filter mesh 2 and obtaining considerable filter versatility.

As the suction nozzle comes into direct contact with the protective mesh 3, the cleaning action is very effective.

Claims

1. A self-cleaning filter with a permeable support (1 ) on which a filter mesh (2) is disposed, characterised by comprising a permeable protective element (3) for protecting the filter mesh (2) and disposed on it such that the filter mesh (2) is interposed between the permeable support (1 ) and the protective element (3).

2. A self-cleaning filter as claimed in claim 1 , characterised in that said protective element (3) comprises a protective mesh.

3. A self-cleaning filter as claimed in claim 1 , characterised in that the permeable support (1 ) is cylindrical.

4. A selfcleaning filter as claimed in claim 1 , characterised by comprising a cleaning member (4) arranged to suck in the dirt deposited on the filter mesh (2) and on the protective element (3).

5. A self-cleaning filter as claimed in claim 4, characterised in that said cleaning member (8), at least during the cleaning operation, slides on the protective element (3) while touching it.

6. A self-cleaning filter as claimed in claim 4, characterised in that said cleaning member (4) can translate and rotate.

7. A self-cleaning filter as claimed in claim 4, characterised in that said cleaning member (4) comprises at least one suction nozzle (8) which slides on a secondary tube (7).

8. A selfcleaning filter as claimed in claim 7, characterised by comprising an elastic spacer (9) disposed on the secondary tube (7) to urge the suction nozzle (8) towards the protective element (3) and to protect the secondary tube (7) from dirt deposition.

9. A self-cleaning filter as claimed in claim 3, characterised by comprising two fixing rings (11 , 12) for clamping together the permeable support (1 ), the filter mesh (2) and the protective element (3).

10. A self-cleaning filter as claimed in claim 2, characterised in that said protective mesh (3) is of plastic material.

11. A self-cleaning filter as claimed in claim 2, characterised in that said protective mesh (3) is formed from woven threads.

12. A self-cleaning filter as claimed in claim 2, characterised in that said protective mesh (3) has mesh apertures of size substantially between 1 and 2 mm.