Double wiper seal arrangement

Claim 1

Double wiper arrangement comprising a wiper ring made from a tough elastic material and fitted in the groove of one of two machine parts which are movable in a direction perpendicular to the said groove, and a stressing ring made from a rubber-elastic material, arranged between the wiper ring and the base of the groove and loading the wiper ring in the radial direction, the wiper ring being provided on its one end with a surface portion which rests flat against the other machine part, with an edge near its other end which rests against the other machine part and which is formed by the line of intersection of two conical surfaces rising outwardly and towards the flat surface portion, respectively, and with a recess arranged on its side facing the base of the groove, opposite the flat surface portion, for receiving the stressing ring, characterized by the combination of the following features: (1) the said groove is only little larger than the width of the said wiper ring, and the depth and width of the said recess as well as the dimensions of the said stressing ring are adapted to each other in such a manner that (a) the said wiper ring is retained in the groove in contact with the flank of the groove which is opposite to the said stressing ring, at least under normal operating conditions, and (b) the maximum of pressure exerted by the said stressing ring is situated above the inner edge of the said flat surface portion, (2) the recess extending concentrically to the base of the said groove rises towards the end of the said wiper ring so that the space accommodating the said stressing ring gets narrower towards the end of the said wiper ring and the force exerted by the said stressing ring produces a contact pressure which declines at least nearly linearly along the said flat surface portion, starting from its inner end, but is still defined at the outer end thereof, and (3) the end face adjacent the outer conical surface is provided with radial relief grooves.