Self tightening venting end cap for vehicle wheel bearing

A wheel bearing and end cap assembly, comprising,

• an inner spindle and coaxial outer hub having an annular edge including a cylindrical inner surface defining a bearing interior space that is subject internal pressure fluctuations relative to the outside pressure,
• an end cap integrally formed of a flexible material and including a first, radially outer channel of generally U shaped cross section facing axially inwardly of said hub and sized so as to tightly grip and seal against said annular edge,
• a second, radially inner channel of generally U shaped cross section facing axially outwardly of said hub and having a cylindrical wall shared with said outer channel and sized so as to closely abut said hub edge inner cylindrical surface when said end cap is in a free, unstressed state, said second channel also having a generally annular base which, in a free state, slopes radially outwardly at a slight angle relative to plane that is perpendicular to said hub, and,
• a central cup opening axially inwardly of said hub and forming the innermost wall of said second channel and exposed on the outside to ambient pressure and on the inside to internal bearing pressure,
• whereby, when said internal pressure is lower than ambient, said cup is forced axially inwardly, tending to flatten said base and bend said shared channel wall outwardly and into tighter sealing abutment with said hub, and when said internal pressure is higher, said cup is forced axially outwardly, tending to bend said shared channel wall inwardly and away from said hub to allow venting.