Filter structure for separation of water from fluids in the motor vehicle sector

1. A filter structure ( 100 ) for separating water from a fluid, the filter ( 100 ) comprising an absorbent filter membrane ( 2 ) constituted by a non-woven textile ( 20 ), wherein the absorbent filter membrane ( 2 ) comprises a first face ( 2 a ) turned upstream in a crossing direction (F) of the fluid being filtered and a second face ( 2 b ), opposite to the first face ( 2 a ) and turned downstream in the crossing direction (F) of the fluid being filtered, wherein the non-woven textile ( 20 ) is constituted by a bearing lattice ( 21 ) and by a super-absorbent material ( 22 ), which expands when it absorbs water, fixed to the bearing lattice ( 21 ), wherein the super-absorbent material ( 22 ) is present in a smaller quantity than 70% in dry weight with respect to a dry weight of the non-woven textile ( 20 ), and wherein the super-absorbent material ( 22 ) is operable between a dry or unsaturated configuration, in which the non-woven textile ( 20 ) has an open porosity between the bearing lattice ( 21 ) and the super-absorbent material ( 22 ), and a saturation configuration, in which the expansion of the super-absorbent material ( 22 ) closes the open porosity between the bearing lattice ( 21 ) and the super-absorbent material ( 22 ), characterized in that fibers that constitute the bearing lattice ( 21 ) define a pathway having at least an upstream end, in the crossing direction (F), which defines a portion of the first face ( 2 a ) or emerges with respect thereto both in dry or unsaturated configuration and in saturation configuration of the superabsorbent material ( 22 ), and a downstream end, in the crossing direction (F), which defines a portion of the second face ( 2 b ) or emerges therefrom both in dry or unsaturated configuration and in saturation configuration of the super-absorbent material ( 22 ) so that, when the super-absorbent material ( 22 ) is in saturation configuration, the non-woven textile ( 20 ) has a permeability to the fluid that is not nil by capillarity to the interface between the bearing lattice ( 21 ) and the super-absorbent material ( 22 ).

2. The filter structure ( 100 ) of claim 1 , wherein the super-absorbent material ( 22 ) is selected from a group consisting of polyacrylate and polyacrylamide.

3. The filter structure ( 100 ) of claim 1 , wherein the super-absorbent material ( 22 ) is constituted by fibers having an average diameter comprised between 10 μm and 40 μm in dry conditions and interlaced with the bearing lattice ( 21 ).

4. The filter structure ( 100 ) of claim 1 , wherein the super-absorbent material ( 22 ) is constituted by grains fixed to the bearing lattice ( 21 ).

5. The filter structure ( 100 ) of any claim 1 , wherein the super-absorbent material ( 22 ) in a saturation configuration has a volume comprised between 30 and 70 times the volume of the super-absorbent material ( 22 ) in a dry configuration.

6. The filter structure ( 100 ) of claim 1 , wherein the bearing lattice ( 21 ) is made of a non-absorbent material, in a quantity such as to complete the 100% of the dry weight of the non-woven textile.

7. The filter structure ( 100 ) of claim 1 , wherein the bearing lattice ( 21 ) is made of a hydrophobic material.

8. The filter structure ( 100 ) of claim 6 , wherein the bearing lattice ( 21 ) is made of a material selected from a group consisting of polyester (PE), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polypropylene (PP) or other polymers functionalized with silicone or polytetrafluorosilicone.

9. The filter structure ( 100 ) of claim 1 , wherein the bearing lattice ( 21 ) is made of a hydrophilic material.

10. The filter structure ( 100 ) of claim 6 , wherein the bearing lattice ( 21 ) is made of a material selected from a group consisting of polyamide, aliphatic polyamide, cellulose, rayon and acetate.

11. The filter structure ( 100 ) according to claim 1 , wherein the non-woven textile ( 20 ) which constitutes the absorbent filter membrane ( 2 ) has a dry porosity of not lower than 85%.

12. The filter structure ( 100 ) according to claim 1 , wherein the non-woven textile ( 20 ) which constitutes the absorbent filter membrane ( 2 ) has a dry 30 porosity, in the fluid crossing direction, comprised between 0.3 mm and 30 mm.

13. The filter structure ( 100 ) of claim 1 , wherein, when the super-absorbent material ( 22 ) is in saturation configuration, the absorbent filter membrane ( 2 ) has a substantially coalescent behavior in which the absorbent filter membrane ( 2 ) releases water drops from a downstream side of said absorbent filter membrane ( 2 ), in the fluid crossing direction, having larger dimensions with respect to the water drops contained in the fluid to be filtered reaching an upstream side of the absorbent filter membrane ( 2 ).

14. The filter structure ( 100 ) of claim 1 , comprising a first filter membrane ( 1 ) positioned upstream of the absorbent filter membrane ( 2 ) in the crossing direction of the fluid.

15. The filter structure ( 100 ) of claim 14 , wherein the absorbent filter membrane ( 2 ) is dimensioned in such a way that the pressure drop caused on the fluid under filtration, when the super-absorbent material ( 22 ) is in saturation configuration, is smaller than the pressure drop caused by the first filter membrane ( 1 ) on the same fluid under filtration.

16. The filter structure ( 100 ) of claim 15 , wherein both the first filter membrane ( 1 ) and the absorbent filter membrane ( 2 ) have a substantially toroidal shape having a longitudinal axis (A) and respective cross-sections having shapes different from each other.

17. The filter structure ( 100 ) of claim 16 , wherein the first filter membrane ( 1 ) has a star-shaped cross-section and the absorbent filter membrane ( 2 ) has a circular cross-section.

18. The filter structure ( 100 ) of claim 14 , wherein the first filter membrane ( 1 ) is a depth filter membrane.

19. The filter structure ( 100 ) of claim 1 , further comprising a hydrophobic filter membrane ( 3 ) positioned downstream of the coalescent absorbent filter membrane ( 2 ) in the crossing direction of a fluid being filtered.

20. A filter cartridge ( 40 ) for filtering a fluid containing water which comprises a support plate ( 41 , 42 ) fixed to a filter structure ( 100 ) according to claim 1 , wherein the absorbent filter membrane ( 2 ) of the filter structure ( 100 ) has a substantially toroidal shape and the support plate ( 41 , 42 ) is fixed to one of the ends of the absorbent filter membrane ( 2 ).

21. A filter group ( 10 ) comprising a casing ( 30 ) provided with an inlet ( 33 ) for a fluid to be filtered, a first outlet ( 34 ) for the filtered fluid and a second output ( 35 ) for water separated from the fluid being filtered and a filter cartridge ( 40 ), according to claim 20 , wherein the absorbent filter membrane ( 2 ) is able to separate the internal volume of the casing ( 30 ) into two environments, of which a first environment in communication with the inlet ( 33 ) and a second environment.

22. The filter structure ( 100 ) according to claim 1 , wherein the non-woven textile ( 20 ) which constitutes the absorbent filter membrane ( 2 ) has a dry porosity of not lower than 95%.