Filter for a filtration device

1. A filter, dimensioned for insertion into an inlet duct of a water filtration system, the inlet duct extending around an inlet axis, the inlet duct defining an inlet diameter, the inlet duct being positioned to collect water to be filtered, the filter comprising:

an annular upper end of the filter, delimiting an opening around a longitudinal axis of the filter, so as to allow an admission of water into the filter, the annular upper end defining a filter diameter;

a bottom wall, forming a bottom of the filter, extending opposite the opening; and

a side wall, extending between the annular upper end of the filter and the bottom wall, around the longitudinal axis;

the side wall and/or the bottom wall having orifices, so as to allow water to flow through the orifices and to retain solid elements, the size of which is greater than a filtration size, defined by the orifices;

wherein the side wall comprises:

a plurality of arms, each arm extending between a lower edge of the arm and an upper edge of the arm, the lower edge of the arm being connected to the bottom wall, the upper edges of the arms of the plurality of arms forming the annular upper end of the filter;

each arm extending from the bottom wall towards the annular upper end, away from the longitudinal axis, each arm extending along an inclination, the inclination between each arm and the longitudinal axis being adjustable, so that the filter diameter of the annular upper end is variable according to the inclination of each arm;

so that when the filter is inserted into the inlet duct, the longitudinal axis being parallel to the inlet axis, the inclination of the arms is adjusted so that the filter diameter of the annular upper end is adapted to the inlet diameter.

2. The filter of claim 1 , further comprising a complementary wall extending between each arm.

3. The filter of claim 2 , wherein the complementary wall comprises elementary sections, each elementary section extending between two adjacent arms and being connected thereto.

4. The filter of claim 3 , wherein at least one elementary section has orifices, so as to allow the flow of water therethrough.

5. The filter of claim 3 , wherein at least one elementary section, and an arm to which the elementary section is connected, partially overlap.

6. The filter of claim 2 , wherein the complementary wall is formed by a filter membrane, extending against the bottom wall and against each arm.

7. The filter of claim 1 , wherein each arm, in the absence of stress on the arm, extends at an angle of inclination at rest with respect to the longitudinal axis.

8. The filter of claim 1 , wherein the bottom wall has a diameter, perpendicular to the longitudinal axis, strictly less than the diameter of the annular upper end.

9. The filter of claim 1 , wherein an angle of inclination at which each of at least two arms extends relative to the longitudinal axis is adjustable.

10. The filter of claim 9 , further comprising a wire connected to the at least two arms and actuatable to selectively move the at least two arms towards or away from the longitudinal axis.

11. The filter of claim 10 , wherein the upper edge of at least two arms has a groove, so that the wire can slide into the groove.

12. The filter of claim 1 , further comprising at least one leg, connected to and extending from the bottom wall, the leg being positioned and dimensioned to rest within the inlet duct when the filter is inserted in the inlet duct.

13. A method for inserting a filter, according to claim 1 , into an inlet duct of a filtration system, the inlet duct extending around an inlet axis, according to an inlet diameter, the method comprising:

adjusting the diameter of the filter by exerting a stress on arms of the filter, so as to bring the latter closer to the longitudinal axis of the filter, so as to obtain the filter diameter of the annular upper end smaller than the inlet diameter;

inserting the filter into the inlet duct, the longitudinal axis of the filter being coincident with the inlet axis, so that after insertion, the bottom wall is disposed at a lower level, relative to the vertical, than the annular upper end; and

after the insertion of the filter, releasing the arms so that the arms incline with respect to the longitudinal axis, towards the inlet duct, until the arms rest against the inlet duct.