Tensioner

Abstract

The invention comprises a self-contained mechanical belt tensioner that produces damping which is a function of the applied hubload through the effect of frictional forces derived from the sliding action of mutually opposing wedges. A first wedge or conical piston is contained within a housing. The conical piston cooperates with a second or conical wedge. A surface of the conical wedge slides on the inner surface of the housing. The conical wedge is expandable in a direction normal to the inner surface of the housing. A spring urges the conical wedge into engagement with the conical piston. As the pulley is loaded, as with an impulse load, the piston will move into the conical wedge. This, in turn, will cause the conical wedge to expand against the inner surface of the housing. The expansion of the conical wedge in the housing will increase the frictional force between the conical wedge and the housing. This will have the effect of damping movements of the conical piston and, in turn, of the pulley. The greater the impulse, then the greater the expansion of the conical wedge. This increases the resultant frictional force resisting movement between the conical wedge and the housing. As the load moves toward a minimum, the frictional force is abated to a low level allowing ease of retraction of the piston.

We claim:  
     
         1 . A tensioner comprising: 
 a housing having a housing surface;    a wedge having a wedge surface that slidingly engages the housing surface, the wedge further describing a hole;    a piston having a first end cooperatively engaging the hole;    a pivot arm having a pulley journaled to an end, the pivot arm pivotably mated to a surface and having a second end bearing on an end of the piston opposite the first end; and    a compressible member biasing the wedge toward the piston, whereby movement of the wedge against the first end causes the wedge to radially expand against the housing surface thereby damping a movement of the piston.    
     
     
         2 . The tensioner as in  claim 1 , wherein: 
 the wedge hole comprises a frustoconcical hole; and    the piston first end comprises a frustoconcical shape that cooperatively engages the frustoconical hole.    
     
     
         3 . The tensioner as in  claim 2 , wherein the wedge further comprises: 
 at least one slot, the slot oriented so the circumference of the wedge is radially expandable in response to a movement against the piston first end.    
     
     
         4 . The tensioner as in  claim 3 , further comprising: 
 an adjuster bearing on an end of the compressible member and the housing whereby a compressible member preload may be changed.    
     
     
         5 . The tensioner as in  claim 4 , wherein: 
 the wedge outer surface further describes a pleated form; and    the inner surface further describes a pleated form that cooperates with the pleated form of the wedge outer surface.    
     
     
         6 . The tensioner as in  claim 5 , wherein the housing further comprises a cylinder.  
     
     
         7 . The tensioner as in  claim 5 , wherein the wedge surface comprises a nonmetallic material.  
     
     
         8 . The tensioner as in  claim 1 , wherein the compressible member comprises a spring.  
     
     
         9 . A tensioner comprising: 
 a first housing having a first inner surface;    a second housing having a second inner surface and an outer surface, the outer surface slidingly engaged with the first inner surface;    a first compressible member resisting a movement between the first housing and second housing;    a piston having a first end and a second end, the first end being affixed to the first housing and being substantially parallel to a major axis of the first housing;    a camming body describing a central hole and having a surface slidingly engaged with the second inner surface and the hole slidingly engaged with the second end; and    a second compressible member urging the camming body against the second end, whereby the camming body is radially expandable against the second inner surface.    
     
     
         10 . The tensioner as in  claim 9 , wherein: 
 the camming body central hole further comprises a frustoconcical hole; and    the piston second end further comprises a frustoconcical shape that cooperatively engages the frustoconical hole.    
     
     
         11 . The tensioner as in  claim 10 , wherein the camming body further comprises: 
 at least one slot, the slot oriented so the circumference of the camming body is variable in response to a movement against the piston second end.    
     
     
         12 . The tensioner as in  claim 11 , wherein: 
 the camming body surface further describes a pleated form; and    the second housing second inner surface further describes a pleated form that cooperates with the pleated form of the camming body surface.    
     
     
         13 . The tensioner as in  claim 12 , wherein: 
 the first housing describes a cylinder; and    the second housing describes a cylinder.    
     
     
         14 . The tensioner as in  claim 13 , wherein the camming body surface comprises a nonmetallic material.  
     
     
         15 . The tensioner as in  claim 14 , wherein the second compressible member bears upon the first housing.  
     
     
         16 . The tensioner as in  claim 14 , wherein: 
 the first compressible member comprises a spring; and    the second compressible member comprises a spring.    
     
     
         17 . The tensioner as in  claim 14  further comprising: 
 a bearing surface attached to the piston, the bearing surface extending normally to a piston axis; and  
 the second compressible member bears upon the bearing surface.  
 
     
     
         18 . A damper comprising: 
 a housing having a housing surface;    a wedge having a surface that slidingly engages the housing surface, the wedge further describing a hole;    a piston having a first end cooperatively engaging the hole; and    a compressible member biasing the wedge toward the piston, whereby movement of the wedge against the first end causes the wedge to radially expand against the housing surface thereby damping a movement of the piston.    
     
     
         19 . The damper as in  claim 18 , wherein: 
 the wedge hole comprises a frustoconcical hole; and    the piston first end comprises a frustoconcical shape that cooperatively engages the frustoconical hole.    
     
     
         20 . The damper as in  claim 19 , wherein the wedge further comprises: 
 at least one slot, the slot oriented so the circumference of the wedge is radially expandable in response to a movement against the piston first end.    
     
     
         21 . The damper as in  claim 20 , wherein: 
 the wedge surface further describes a pleated form; and    the housing surface further describes a pleated form that cooperates with the pleated form of the wedge surface.    
     
     
         22 . The damper as in  claim 21 , wherein the housing further comprises a cylinder.  
     
     
         23 . The damper as in  claim 22 , wherein the wedge surface comprises a nonmetallic material.  
     
     
         24 . The damper as in  claim 23 , wherein the compressible member comprises a spring.  
     
     
         25 . A damper comprising: 
 a first housing having a first housing surface;    a wedge describing a wedge hole and having a wedge surface for slidingly engaging the first housing surface;    a second housing, .the first housing coaxially and slidingly engaging the first housing;    a piston having a first end and a second end, the first end engaging the wedge central hole and the second end affixed to the second housing;    a first compressible member urging the wedge into contact with the piston first end;    a second compressible member urging the first housing away from the second housing.    
     
     
         26 . The damper as in  claim 25 , wherein: 
 the wedge hole comprises a frustoconcical hole; and    the piston first end comprises a frustoconcical shape that cooperatively engages the frustoconical hole.    
     
     
         27 . The damper as in  claim 26 , wherein the wedge further comprises: 
 at least one slot, the slot oriented so the circumference of the wedge is radially expandable in response to a movement against the piston first end.    
     
     
         28 . The damper as in  claim 27 , wherein: 
 the wedge outer surface further describes a pleated form; and    the first housing surface further describes a pleated form that cooperates with the pleated form of the wedge surface.    
     
     
         29 . The damper as in  claim 28 , wherein; 
 the first housing further comprises a cylinder; and    the second housing further comprises a cylinder.    
     
     
         30 . The damper as in  claim 29 , wherein at least the wedge surface comprises a nonmetallic material.  
     
     
         31 . The damper as in  claim 30 , wherein: 
 the first compressible member comprises a spring; and    the second compressible member comprises a spring.    
     
     
         32 . A damper comprising: 
 a first housing having a first housing surface;    a second housing having a second housing surface;    a wedge having a wedge surface that coaxially and slidingly engages the first housing surface and slidingly engages the second housing surface, the wedge further comprising a wedge hole surface describing a hole into which the second housing surface is engaged;    a compressible member biasing the wedge toward the first housing, whereby movement of the wedge against the first housing surface causes the wedge to radially compress against the second housing surface thereby damping a movement of the first housing.    
     
     
         33 . The damper as in  claim 32 , wherein the wedge hole comprises a cylindrical hole.  
     
     
         34 . The damper as in  claim 33 , wherein the wedge further comprises: 
 at least one slot, the slot oriented so the circumference of the wedge is radially compressible in response to a movement against the first housing surface.    
     
     
         35 . The damper as in  claim 34 , wherein: 
 the wedge hole further describes a pleated form; and    the second housing surface further describes a pleated form that cooperates with the pleated form of the wedge hole.    
     
     
         36 . The damper as in  claim 35 , wherein: 
 the first housing further comprises a cylinder; an    the second housing further comprises a cylinder.    
     
     
         37 . The damper as in  claim 36 , wherein the wedge hole surface comprises a nonmetallic material.  
     
     
         38 . The damper as in  claim 37 , wherein the compressible member comprises a spring.  
     
     
         39 . A damper comprising: 
 a first housing having a first housing surface;    a piston having a piston surface;    a wedge having a wedge surface that coaxially and slidingly engages the first housing surface and slidingly engages the piston surface, the wedge further comprising a wedge hole surface describing a hole into which the piston surface is engaged;    a first compressible member biasing the wedge toward the first housing, whereby movement of the wedge against the first housing surface causes the wedge to radially compress against the piston surface thereby damping a movement of the piston; and    a second compressible member biasing the first housing away from the piston.    
     
     
         40 . The damper as in  claim 39 , wherein the hole comprises a cylindrical hole.  
     
     
         41 . The damper as in  claim 40 , wherein the wedge further comprises: 
 at least one slot, the slot oriented so the circumference of the wedge is radially compressible in response to a movement against the first housing surface.    
     
     
         42 . The damper as in  claim 41 , wherein: 
 the wedge hole surface further describes a pleated form; and    the piston surface further describes a pleated form that cooperates with the pleated form of the wedge hole.    
     
     
         43 . The damper as in  claim 42 , wherein the first housing further comprises a cylinder.  
     
     
         44 . The damper as in  claim 43 , wherein the wedge hole surface comprises a nonmetallic material.  
     
     
         45 . The damper as in  claim 44 , wherein: 
 the first compressible member comprises a spring; and    the second compressible member comprises a spring.    
     
     
         46 . The damper as in  claim 32 , wherein the first housing surface describes a conical shape having an angle in the range of 0°to 30°.  
     
     
         47 . The damper as in  claim 39 , wherein the first housing surface describes a conical shape having an angle in the range of 0°to  30 °.  
     
     
         48 . A damper comprising: 
 a first member having a first surface;    a second member having a second surface, the second surface being co-axially moveable with respect to the first surface;    a frictional member having a changeable circumference slidingly engaging the first surface and the second surface;    a compressible member urging the frictional member against the first surface whereby a circumference of the frictional member is changed resulting in an enlarged frictional contact with the second surface.    
     
     
         49 . The damper as in  claim 48 , wherein the frictional member further comprises at least one slot, the slot oriented so the circumference of the frictional member is changeable.  
     
     
         50 . The damper as in  claim 49  further comprising: 
 a second compressible member urging the first member away from the second member.