Patent ID: 7553409

Claim:
A replaceable liquid filter comprising: a substantially cup-shaped housing with a concentrically disposed outlet opening for filtered liquid and at least one inlet opening for liquid to be filtered, and a filter element disposed in contact with an end plate in a sealing manner between the inlet opening and the outlet opening, said filter element defining an effective filter element surface, wherein: the housing is connected to a top plate, and the top plate is coupled to said end plate and encloses a displacement space which is disposed exteriorly of said end plate in a liquid feed chamber in a part which mates with the liquid filter; an inlet opening in the top plate is disposed in the area of the displacement space; a check valve is disposed in said displacement space which prevents return flow from said displacement space through the inlet opening in the top plate such that liquid cannot leak from the filter when the filter is detached for replacement; and a backflow check valve is disposed in the area of the outlet opening axially outside the effective filter element surface.