Patent ID: 8043072

Claim:
A piston pump comprising: a pump housing defining a cylinder; a piston reciprocatively inserted in said cylinder to define a pump chamber in said cylinder, said pump chamber having a volume that changes with the reciprocating movement of said piston; a discharge valve provided at an outlet of said pump chamber and including a tubular valve seat member having a bottom and defining a filter mounting hole having an opening facing said pump chamber; and a filter for filtering a liquid in the form of a flat metal plate comprising a main body formed with a plurality of filter holes in a central portion thereof, and a plurality of projections integrally and radially outwardly extending from a perimeter of said main body so as to be circumferentially spaced apart from each other; said filter being received in said filter mounting hole with said projections bent toward said opening of said filter mounting hole and in the direction of thickness of said main body, with tips of the projections in contact with an inner surface of said filter mounting hole, whereby said filter is fixed to said valve seat member by the contact between said projections and the inner surface of said filter mounting hole.