Internal Elastomer Damper for Vehicular Propeller Shafts

Abstract

Ringing noise in a tube or in tubes comprising a propeller shaft of an automotive drive is attenuated by an elastomeric ring positioned in each shaft. The elastomeric ring is a split ring, preferably made of recycled rubber, wherein the ring normally has a rectangular shape and is bent into a cylindrical shape for insertion in the tube. The outward bias of the ring is sufficient to hold the ring in place within the tube, while a gap in the material of the ring allows the ring to exert further expansive force against the inner surface of the tube while the tube is rotating. A single ring located midway between the ends of a tube is sufficient to attenuate ringing noise in one example of a tube, however a plurality of spaced rings may be used in other tube configurations to attenuate ringing noise. Preferably, the elastomeric ring has an axial extent of about 5% of the length of the tube.

1 . A propeller shaft for a vehicle, comprising:
 a tube having first and second ends and an inner surface and an outer surface; and   a dampener, said dampener being only a single-piece ring of elastomeric material which is disposed within the tube and having an outer surface in contact with the inner surface of the tube at a location intermediate the ends of the tube, the ring having an axial extent and a radial thickness sufficient to damp the tube, said ring being a flat polygon shape of the elastomeric material that is flat when in a relaxed state and when bent into ring shape for insertion into the tube retains a bias tending to return to the relaxed state and urging the outer axially extending surface into frictional engagement with the inner surface of the tube, said ring being solely of said elastomeric material with no additional support and being retained within the tube solely by frictional force.   
     
     
         2 . The propeller shaft of  claim 1  wherein the elastomeric material is rubber. 
     
     
         3 . The propeller shaft of  claim 2  wherein the elastomeric material is recycled rubber. 
     
     
         4 . The propeller shaft of  claim 3  wherein the ring is axially positioned within the tube at a location midway between the ends of the tube. 
     
     
         5 . The propeller shaft of  claim 1  wherein the flat polygon shape of the elastomeric material has opposed ends that upon bending of the flat polygon into the ring shape define a split gap in the shape of the ring enabling the ring to expand and urge the outer surface into frictional engagement with the inner surface of the tube and the gap permits permit centrifugal force to further push the outer surface of the ring against the inner surface of the tube. 
     
     
         6 . The propeller shaft of  claim 1  wherein the ring has an axial extent in a range of about 3 to 6% of the length of the tube. 
     
     
         7 . The propeller shaft of  claim 6  wherein the ring has an axial extent of about 5% of the length of the tube. 
     
     
         8 . The propeller shaft of  claim 6  wherein the flat polygon shape of the elastomeric material has opposed ends that upon bending of the flat polygon into a ring shape define a split gap in the shape of the ring shape enabling the ring to expand and urge the outer surface into frictional engagement with the inner surface of the tube and permit centrifugal force to further push the outer surface of the ring against the inner surface of the tube. 
     
     
         9 . The propeller shaft of  claim 8  wherein the elastomeric material is rubber. 
     
     
         10 . The propeller shaft of  claim 9  wherein the elastomeric material is recycled rubber. 
     
     
         11 . The propeller shaft of  claim 1  wherein the propeller shaft is comprised of two similarly configuring tubes with similar damping rings. 
     
     
         12 . A propeller shaft for a vehicle, comprising:
 a cylindrical tube having first and second ends and an inner surface and an outer surface; and   a dampener of only a single piece of generally rectangular and flat-shaped piece of relaxed elastomeric material bent to a split-ring cylindrical shape for insertion into the tube, said ring shape having a cylindrical outer surface that is frictionally engaged with the inner surface of the tube by the bias of the elastomeric material seeking to return to it relaxed flat shape, said frictional engagement being increased by the centrifugal forces acting upon the elastomeric material during rotation of the tube so that the elastomeric material is retained against shifting within the tube solely by friction between the tube and the elastomeric material, said piece of elastomeric material having no supporting structure and being engaged with the tube solely by the friction and the centrifugal force.   
     
     
         13 . The propeller shaft of  claim 12  wherein the piece of elastomeric material is rubber and when frictionally engaged within the tube has an axial extent of about 3 to 6% of the axial length of the tube. 
     
     
         14 . The propeller shaft of  claim 12  in which the piece of elastomeric material is frictionally retained within the tube at approximately midway between the first and second ends of the tube. 
     
     
         15 . A propeller shaft for a vehicle, comprising:
 a tube having first and second ends and an inner surface and an outer surface; and   a dampener of only a single piece of unsupported elastomeric material having opposed ends and being generally flat in a relaxed condition and being self-biased toward the relaxed condition when bent into a cylindrical ring-shape in which the opposed ends have a gap therebetween to permit expansion of the diameter of the cylindrical ring-shape, said piece of elastomeric material being located inside the tube and frictionally engaging with the inner surface of the tube so that the elastomeric material is retained solely by friction against shifting within the tube.