WO2010115643A1

WO2010115643A1 - Improved filter cartridge

Info

Publication number: WO2010115643A1
Application number: PCT/EP2010/050859
Authority: WO
Inventors: Maurizio Moretto
Original assignee: Laica S.P.A.
Priority date: 2009-04-08
Filing date: 2010-01-26
Publication date: 2010-10-14
Also published as: JP2012523307A; EP2417064A1; ITPD20090022U1; TW201036684A

Abstract

A filter cartridge (1) comprising a container (2) for a filter material (3) provided with at least one inlet opening (3a, 3b, 3c) for the fluid to be filtered and at least one outlet opening (5) for the filtered fluid, these openings (5) being provided with retaining means (6, 7, 8) arranged to retain the filter material (3) within the container (2) and the cartridge comprising at least a further retaining cap (10) applied to the container (2) in the vicinity of at least the one outlet opening (5) and arranged to retain any filter material (3) which may have escaped from the retaining means (6, 7, 8) through at least the one outlet opening (5), collecting the material between the container (2) and the cap (10).

Description

Improved filter cartridge

DESCRIPTION Technical field

The invention relates to a filter cartridge of the replaceable type, designed in particular for percolation filtration systems such as jugs to purify water for domestic use, kettles, teapots and the like. Background art

These cartridges generally comprise a container of plastics material which houses a filter material which is generally granular. The container is in turn provided with at least one inlet opening for the fluid to be filtered and at least one outlet opening for the filtered fluid, both provided with retaining means arranged to retain the filter material within the container. The retaining means to which the invention relates are those disposed at the outlet opening and are generally embodied as grids (the term grid is understood to include nets, foam, membranes, calibrated holes and the like) with a mesh whose narrowness depends on the filter material to be retained.

It will be appreciated that the retaining action is the more effective, the narrower the mesh of the grids, with the result that it is possible effectively to retain even very minute filter material with a grid with narrow mesh.

These cartridges nevertheless have to satisfy a second requirement which clearly conflicts with the first requirement. It will be appreciated that grids with very narrow mesh interfere more with the flow of filtered fluid and have, with the same cross-section of the outlet opening, a substantial influence on the instantaneous rate of flow through the cartridge. The flow may therefore vary substantially over time leading to a disadvantageous reduction of the contact time of the fluid to be filtered with the filter material.

Grids with narrow mesh may also become blocked because of the accumulation of the retained filter material.

Moreover, using grids with particularly narrow mesh in order to maximise the retention of the filter material has an adverse effect on the stability of the times taken by the fluid to be filtered to flow through the cartridge between the beginning and end of each filtration cycle, which has an adverse effect on the performance of the cartridge itself.

This effect is further exacerbated by the blockages which tend to form over time as the cartridge is used, bearing in mind that the grid cannot normally be accessed for maintenance and cleaning. Description of the invention The technical problem to which the present invention relates is therefore that of providing an improved filter cartridge which is structurally and functionally designed to remedy the drawbacks of the prior art cited above. Within this problem, an object of the invention is to provide a filter cartridge able correctly to retain the filter material and effectively to remove the filter material from the filtered fluid.

A further object is to provide a filter cartridge in which the means for retaining the filter material may be subject to periodic maintenance and cleaning.

Brief description of the drawings The advantages and features of the invention will become clear from the following detailed description of a preferred, but not exclusive, embodiment thereof, made with reference to the appended drawings which are provided by way of non-limiting example and in which :

Fig. 1 is an exploded perspective view of a cartridge according to the present invention;

Fig. 2 is a cross-sectional view of the cartridge of Fig. 1 in the assembled state;

Fig. 3 is a plan view from the bottom of the cartridge of the separate components of the cartridge shown in the preceding Figures. Preferred embodiment of the invention

In the drawings, a replaceable cartridge for filtration systems of the percolation type is shown overall by 1, into which the fluid to be filtered - generally water - is introduced under the effect of gravity from a first to a second tank, superimposed on one another, via a duct in which the cartridge is detachably inserted. Systems of this type are illustrated, for instance, in Patent Application WO2009/012832.

The cartridge 1 contains a container 2 for a filter material 3 which is generally granular and is disposed in the container to form a filter bed. The container 2 is generally made from plastics material by assembling an upper portion 4a and a lower portion 4b and then securing them to one another. The upper portion 4a is provided with a set of inlet openings 3a, b and c for the fluid to be filtered. The lower portion 4b is provided with two (in practice at least one is needed) outlet openings for the filtered fluid, both shown by 5. Retaining means are provided in the vicinity of all the above-mentioned openings in order to retain the filter material within the container. In the embodiment shown, these means are formed by grids 6, 7 and 8. A strainer cap 5a is also applied to the outlet openings 5 and bears a calibrated hole 5b arranged to determine and stabilise the time taken by the filtered water to flow through the filter bed 3. The openings to which the present invention relates are in particular the outlet openings 5 protected by the grids shown by 8. These openings each have a passage section Sl (depending on their diameter if they are of circular shape) and the grids 8 have mesh of a predetermined width Al as a result of which they generate a known loss of load when they are traversed by filtered fluid at a known rate of flow which is as constant as possible during the filtration cycle.

According to the invention, the cartridge 1 further comprises a further retaining cap 10 applied to the lower portion of the container and encompassing the latter in the vicinity of its lateral wall 11. The cap 10 in turn has an internal configuration such that it fits, by shape coupling, with the outer surface of the container with a certain spacing of the base surface 12a of the cap from the base 12 of the container so as to leave a chamber 13 arranged temporarily to accumulate the filtered fluid and to collect any grains of filter material, as will be explained in further detail below.

The lower portion of the cap 10 is provided with two further outlet openings 14 through which the filtered fluid is discharged from the cartridge. The outlet openings 14 are preferably, but not necessarily, provided in the vicinity of the openings 5 and have a passage section S2 greater than or at least equal to the section Sl of the first openings 5. They are protected by a respective grid 16 of very narrow mesh which is narrower than the mesh of the grids 8.

In this way, the second grids 16 manage to retain any filter material which may have escaped from the grids 8 and to collect it in the chamber 13 formed between the container 2 and the cap 10. By using passage sections S2 which are overall larger than those of the sections Sl, the flow of filtered fluid is constant even when grids 16 with narrower mesh than the grids 8 are present. This enables more accurate retention of the filter material without, at the same time, being detrimental to the correct operation of the cartridge.

The cap 10 is preferably applied in a detachable manner to the container 2 so that the second grids 16 can be maintained and cleaned when the cap 10 is removed and also so that the cap 10 can be taken from a spent cartridge and re-used on a cartridge with new filter material. Moreover, the second grids 16, as they are not in contact with the filter material, and are disposed in series with the first grids 8, are less likely to be subject to accumulations of filter material and resulting blockages. The invention thus solves the stated problem.

Claims

1. An improved filter cartridge (1) comprising a container (2) for a filter material (3) provided with at least one inlet opening (3a, 3b, 3c) for the fluid to be filtered and at least one outlet opening (5) for the filtered fluid, these openings (5) being provided with retaining means (6, 7, 8) arranged to retain the filter material (3) within the container (2), characterized in that it comprises at least a further retaining cap (10) applied to the container (2) in the vicinity of at least the one outlet opening (5) and arranged to retain any filter material (3) which may have escaped from the retaining means (6, 7, 8) through at least the one outlet opening (5), collecting this material between the container (2) and the cap (10).

2. A filter cartridge (1) according to claim 1, wherein the cap (10) and the container (2) comprise respective lateral walls and the cap (10) may be fitted on the lateral wall (11) of the container (2) by shape coupling.

3. A filter cartridge (1) according to claims 1 or 2, wherein the cap (10) comprises a base wall (12a) which, when the cap (10) is fitted on the container (2), is spaced from a corresponding base wall (12) of the container (2) to form at least one collection chamber (13).

4. A filter cartridge (1) according to claims 1, 2 or 3, wherein the cap (10) is provided with at least one outlet opening (14) whose passage section (S2) is overall greater than or equal to the outlet openings (5) of the container (2).

5. A filter cartridge (1) according to claim 4, wherein the outlet openings (5) of the cap (10) are provided with a grid (16) with narrower mesh than the grid (8) applied to the outlet openings (5) of the container (2).