Plastic piston head assembly - has cup seal held by retainer ring welded to piston flange underside

摘要

Piston comprises: (a) a cylindrical body with a radial horizontal flange (42) from the top edge; (b) a central boss extending from the body underside and of smaller dia.; (c) a circumferential notch in the bottom edge; (d) an annular cup seal (48) engaged against the flange underside (46) and of larger o.d. than the flange, and (e) an annular retainer ring (50) ultrasonically welded to the flange underside to secure the cup seal between them. Flange underside pref. has a downward bead (60) spaced from the body side, and a circumferential recess (62) adjacent to the body side. Ring pref. has a circumferential notch (70) in its interior upper edge cooperating with the notch (72) in the body bottom edge to assist press fitting of the ring about the body. Piston and ring are e.g. of glass-reinforced plastic. -