Vibration-damping device for vehicles and method of manufacturing the same

Abstract

A vehicle vibration-damping device including a rigid housing and an independent mass member housed in the housing and having a metallic mass of circular shape in section and a rubber elastic body layer adhered to the metallic mass. A distance of a gap between opposing surfaces of the housing and the metallic mass in the radial direction, with the housing and metallic mass disposed coaxially, is set to between 0.5 and 2 mm. The rubber elastic body layer is formed around an entire outer peripheral surface of the metallic mass by a vulcanization molding of a rubber material filling the gap, and thermal contraction is used both to cause the rubber elastic body layer to peel from the housing and to cause it to adhere onto the outer peripheral surface of the metallic mass to thereby fabricate a small gap of no more than 0.1 mm. A method of manufacturing the same is also disclosed.

1 . A vehicle vibration-damping device adapted to be installed on a vibrating member to damp vibrations excited therein, comprising: 
 a rigid housing having a cylindrical inner peripheral surface, that is adapted to be attached to the vibrating member; and    an independent mass member including a metallic mass having a circular shape in cross section, and a rubber elastic body layer adhered to an outer peripheral surface of the metallic mass, the independent mass member being housed within the housing with a gap therebetween in a radial direction corresponding to a primary vibration input direction so that the independent mass member is movable relative to the housing in the primary vibration input direction, the vibration-damping device being capable of exhibiting a vibration-damping effect based on the independent mass member moving relative to the housing, and striking the housing, when a vibration is applied,    wherein a distance between opposing surfaces of the inner peripheral surface of the housing and the outer peripheral surface of the metallic mass in the radial direction, when the housing and metallic mass are disposed coaxially, is set to between 0.5 and 2 mm, and    wherein the rubber elastic body layer is formed around an entire outer peripheral surface of the metallic mass by a vulcanization molding of a rubber material filling the gap between the inner peripheral surface of the housing and the outer peripheral surface of the metallic mass, and thermal contraction is used both to cause the rubber elastic body layer to peel from the housing and to cause the rubber elastic body layer to adhere onto the outer peripheral surface of the metallic mass to thereby fabricate a small gap of no more than 0.1 mm, between the opposing surfaces, when the rubber elastic layer member and the housing are disposed coaxially, so that a natural frequency of the independent mass member is set to a frequency band that is higher than a natural frequency of the vibrating member so that the metallic mass repetitively strikes the inner surface of the housing on both sides in the primary vibration input direction through the rubber elastic body layer when a vibration is applied.    
   
   
       2 . A vehicle vibration-damping device according to  claim 1 , wherein the vibration-damping device is disposed in a state where the primary vibration input direction is approximately vertically oriented, and when the vibration-damping device is subjected to at least 2G input vibration, the independent mass member undergoes repetitive strike against the inner peripheral surface of the housing on both sides in the primary vibration input direction.  
   
   
       3 . A vehicle vibration-damping device according to  claim 1 , wherein at least one through hole is fabricated in the housing in a position that avoids the part wherein the independent mass member strikes the housing when a vibration is applied in the primary vibration input direction.  
   
   
       4 . A vehicle vibration-damping device according to  claim 1 , wherein an outer peripheral surface of the rubber elastic body layer and the inner peripheral surface of the housing are fabricated so as to extend in the axial direction with approximately uniform cross sections so that the small gap that is fabricated between the outer peripheral surface of the rubber elastic body layer and the inner peripheral surface of the housing is approximately uniform along the entire length in the axial direction.