Rotary air valve seal arrangement

摘要

A rotary air valve mounted in a case for rotatable movement about an axis to close either one of two adjacent openings has a flexible elastomeric seal that flexibly engages inwardly and outwardly facing curved sealing surfaces on the case to seal the respective openings when the valve closes same. The sealing surfaces have a radius of curvature whose axis is offset from that of the valve so that a predetermined contact pressure is established along the seal at the curved sealing surfaces to tightly seal the openings when the valve is closed but diminishes to zero immediately as the valve is rotated to open either opening to thereafter permit further opening of the valve uninhibited by the seal.