Damping mechanism

Abstract

An asymmetric damping mechanism for use in a belt tensioner. The damping mechanism comprises two parts having substantially similar arcuate shapes for engaging a tensioner. The first part is in contact with the second part at a pivotable point of contact. The point of contact position is determined according to the desired asymmetric damping factor. The first part is also in contact with a spring. The second part is in contact with a tensioner arm. The damping mechanism also comprises two damping shoes, each having a damping band. The damping band is joined to the damping shoe by a plurality of vertical grooves on the damping shoe cooperating with a plurality of grooves on the damping band. The damping mechanism has an asymmetric damping factor in the range of approximately 1.5 to 5.

1 . A damping mechanism comprising: 
 a first arcuate member having a frictional surface;    a second arcuate member having a frictional surface;    the first arcuate member and the second arcuate member engaged with a cooperating arcuate surface; and    the first arcuate member and the second arcuate member having a pivotal engagement whereby a force exerted on the cooperating arcuate surface in a first movement direction is not equal to a force exerted on the cooperating arcuate surface in a second movement direction.    
   
   
       2 . The tensioner as in  claim 1 , wherein the damping mechanism further comprises: 
 a first arcuate member having a first damping surface;    a second arcuate member having a second damping surface;    the first arcuate member and the second arcuate member slidingly engaged with a cooperating surface on the base; and    the first arcuate member and the second arcuate member having a pivotal engagement whereby the first arcuate member and the second arcuate member exert a force to resist a movement of the lever arm in a first movement direction that is not equal to a force exerted to resist a movement of the lever arm in a second movement direction.    
   
   
       3 . The tensioner as in  claim 2 , wherein the pivotal engagement is radially disposed from a lever arm axis of rotation.  
   
   
       4 . The tensioner as in  claim 2 , wherein: 
 the first arcuate member comprises a first damping shoe; and    the second arcuate member comprises a second damping shoe.    
   
   
       5 . The tensioner in  claim 4 , wherein: 
 the first damping surface is engaged with the first damping shoe by a plurality of vertical cooperating members on an engagement surface.    
   
   
       6 . The tensioner as in  claim 5  further comprising: 
 the second damping surface is engaged with the second damping shoe by a plurality of vertical cooperating members on an engagement surface.    
   
   
       7 . A tensioner comprising; 
 a base;    a lever arm pivotally engaged to the base;    a pulley journaled to the lever arm;    means for damping a lever arm movement engaged with the lever arm and engaged with the base;    means for biasing engaged with the means for damping a lever arm movement and the base; and    said means for damping a lever arm movement having an asymmetric damping factor.    
   
   
       8 . The tensioner as in  claim 7 , wherein the means for damping further comprises: 
 a first arcuate member having a first damping surface;    a second arcuate member having a second damping surface;    the first arcuate member and the second arcuate member engaged with a cooperating surface on the base; and    the first arcuate member and the second arcuate member having a pivotal engagement point whereby the first arcuate member and the second arcuate member exert a damping force in a first movement direction that is not equal to a damping force exerted in a second movement direction.    
   
   
       9 . The tensioner as in  claim 8 , wherein the pivotal engagement point is radially disposed from a lever arm axis of rotation.  
   
   
       10 . The tensioner as in  claim 8 , wherein: 
 the first arcuate member comprises a first damping shoe; and    the second arcuate member comprises a second damping shoe.    
   
   
       11 . The tensioner in  claim 10 , wherein: 
 the first damping surface is engaged with the first damping shoe by a plurality of vertical cooperating members on an engagement surface.    
   
   
       12 . The tensioner as in  claim 11  further comprising: 
 the second damping surface is engaged with the second damping shoe by a plurality of vertical cooperating members on an engagement surface.    
   
   
       13 . The tensioner as in  claim 12  wherein the means for biasing comprises a spring.