A filter assembly for filtering a fluid

Filter arrangement for filtering a fluid, comprising an inner chamber (14) defining the housing (12) having an inlet (18) and an outlet (20) for the fluid, in the housing arranged (12), filter element (22), which is permeable for the fluid and dividing the inner chamber (14) into an inlet region (28) and a filtered region (30), and arranged in the housing (12) container (24) with its inner portion (40) defines a configured to receive a liquid additive reservoir and having an upper wall portion (41) and a lower wall portion (51), wherein said reservoir defining container (24) having a first opening (42) which provides a flow connection between the inlet region (28) of the housing (12) and the inner portion (40) of the container (24), and a second opening ( 44) which provides a flow connection between the filtered region (30) of the housing (12) and the inner portion (40) of the container (24), and wherein the first opening (42) allows that through the inlet (18) flows in fluid entering the reservoir, and the second opening (44) allows that an existing reservoir in the liquid additive to the outlet (20) flows, characterized, that the first opening (42) of the container (24) is designed as a capillary tube (48) extending from the container (24) between the housing (12) and the filter element (22) along the length of the filter element (22) to the inlet extending (18) through a distance which is selected so that it is smaller or equal to three quarters of the length of the filter element (22), that the opposite end of the capillary tube (48) in the inner region (40) of the container (24) in the direction of the lower wall portion extends (51) of the container (24) and is formed that the second opening (44) in the upper wall portion (41) of the container (24) spaced laterally disposed from the first aperture (42) and a capillary tube (54) extending into the interior region (40) of the container ( 24).