DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0043] FIG. 1 is a cross-sectional view of the invention. A linear tensioner is shown having a damping section that is distinct from the pivot/pulley section. Housing 1 contains the damping components for the tensioner. Housing 1 in the preferred embodiment is cylindrical. However, housing 1 may have any shape generally compatible with the operation described herein. Pivot arm 3 is pivotably connected to housing 1 . Pulley 8 is journaled to pivot arm 3 . Pulley 8 engages a belt B to be tensioned. Adjuster or adjusting screw 7 having a flange is threaded into an end of housing 1 and is used to adjust or fine tune the spring preload force and hence the damping force by turning clockwise or counterclockwise as required by a user.

[0044] Compressible member or spring 6 bears on wedge 13 . Wedge or camming body 13 comprises a tapered or conical hole 15 . Wedge outer surface 16 is slidingly engaged with housing inner surface 17 . Wedge outer surface 16 may comprise a nonmetallic material, such as plastic or phenolic. Piston 14 comprises a cylindrical shape. End 19 of piston 14 has a tapered or frustoconical shape that cooperates with hole 15 in wedge 13 . End 20 of piston 14 opposite the conical end cooperates with bearing point 18 . Bearing point 18 allows pivot arm 3 to press upon the end 20 of piston 14 without undue binding.

[0045] FIG. 2 ( a ) is a top plan view of the wedge through section 2 a - 2 a in FIG. 3 . Wedge or camming body 13 comprises slots 40 , 41 . Slots 40 project from an outer surface of the wedge toward the hole 15 . Slots 41 project from hole 15 toward an outer surface of the wedge. Slots 40 , 41 allow wedge 13 to radially expand and contract, shown as bi-directional arrow E, as the tensioner operates according to the following descriptions. One should note that although the surface 16 is shown as smooth and of circular shape in this FIG. 2 a , surface 16 may have other shapes or profiles as described in the other figures described in this specification.

[0046] FIG. 2 ( b ) is a side elevation view of the wedge through section 2 b - 2 b in FIG. 3 . Slots 40 extend from a first surface 44 of the wedge and slots 41 extend from an opposing surface 45 of the wedge as compared to the first surface. Slots 40 , 41 further comprise holes 42 , 43 respectively, which allow the wedge sides to expand and contract without causing cracking or failure of the wedge at each slot end.

[0047] FIG. 3 is a side cross-section view of the damping section of the invention as described in FIG. 1 . Movement of the pivot arm 3 drives piston 14 into the wedge 13 . Spring 6 biases wedge 13 into piston 14 . In operation, piston 14 is driven into wedge 13 , thereby expanding wedge 13 against surface 17 . The frictional force between wedge surface 16 and surface 17 damps the motion of the wedge and thereby the motion of the piston 14 . Note that although surface 17 is shown as cylindrical in this FIG. 3 , surface 17 may have other shapes or profiles as shown in the other figures described in this specification.

[0048] FIG. 4 is a perspective view of the wedge. Camming body or wedge 13 comprises surface 16 that slidingly engages inner surface 17 of housing 1 . Wedge 13 , and more particularly, surface 16 may have a pleated or star shape. This shape serves to increase the frictional forces, between surface 16 and inner surface 17 . Inner surface 17 and surface 16 may have any shape, so long as they are able to be properly mated to maximize surface contact between them and are able to slide relative to each other along a common axis, A, without binding.

[0049] FIG. 5 is a perspective view of the piston 14 . Piston 14 comprises tapered end 19 and end 20 . Tapered end 19 cooperates with tapered hole 15 in wedge 13 . Bearing point 18 bears upon end 20 . Although surface 16 is star shaped, tapered end 19 and tapered hole 20 each have a conical or frustoconcical shape. In the preferred embodiment, piston 14 comprises steel, although any durable material having similar frictional and compressive properties would be acceptable.

[0050] FIG. 6 is a perspective view of the housing 1 . Housing 1 comprises inner surface 17 . Inner surface describes a pleated or star profile in order to cooperate with surface 16 of wedge 13 . In the preferred embodiment, housing 1 is constructed of aluminum, although any durable material having similar frictional and strength bearing properties would be acceptable. Housing 1 may b attached to a base (not shown) as part of a tensioner assembly as shown in FIG. 1 .

[0051] The operation of the tensioner is as follows. Reference is made to FIG. 7 ( a ), a schematic free body diagram of the damping mechanism during a compression stroke. During the compression stroke, the hubload HC bears upon piston 14 , which acts upon wedge 14 , shown as R. The movement of the tapered end 19 into hole 15 causes an outer circumference of wedge 13 to increase and press surface 16 against the inner surface 17 . Due to friction between the sides of the tapered end 19 and the sides of the tapered hole 15 , movement of piston 14 in direction C acts to move wedge 13 also in direction C. However, the movement of wedge 13 in direction C is resisted by spring 6 , the spring force being depicted as F _s . A normal force is formed between the sides of the tapered end 19 and the sides of the tapered hole 15 , and is resolved into normal forces between them, N _1C and N _2C . A frictional force acts between the sides of the tapered end 19 and the sides of the tapered hole 15 as well as between the sides of the wedge and the inner surface of the housing. A frictional force resisting the motion of the wedge in the housing is formed. These forces are μN _1C and μN _2C . This force is additive with the spring force, F _s , as each acts in the same direction. As the hubload increases, so increases HC. An increase in HC increases N _1C and N _2C until wedge 13 starts moving, which in turn increases the friction forces μN _1C and μN _2C resisting movement of the wedge in the housing. It should be noted that there is no further substantive increase in N _1C and N _2C when wedge 13 moves.

[0052] On the return stroke, depicted in FIG. 7 ( b ) a free body diagram of the damping mechanism during the return stroke, the hubload is diminished. Once the hubload HR becomes less than the spring force F _s minus friction μN _1R , the wedge will be pushed in direction B. The normal forces, N _1R and N _2R are less than N _1C and N _2C . Further, the friction force vector is in the opposite direction as compared to the compression stroke, μN _1R and μN _2R . This frictional force resists the effort of the spring to move the wedge in direction B. The hubload HR required to keep the blocks in static equilibrium is reduced. Since the hubload is reduced, the frictional forces between the wedge and the inner surface of the housing are correspondingly reduced. Hence, the damping, or frictional force, is greater during the compression stroke than during the return stroke. Therefore, the tensioner exhibits asymmetric damping.

[0053] An alternate embodiment is depicted in FIG. 8 . Damper 100 comprises a cylinder slidingly engaged with another cylinder. Outer tube or housing 101 slidingly engages tube 108 . Cap 105 is attached to tube 101 . Cap 110 is attached to tube 108 . Spring 102 extends between cap 105 and end of tube 108 , thereby urging the tubes apart. Plastic liner 106 facilitates movement between outer tube 101 and tube 108 . Piston 111 is affixed to cap 110 and is parallel to a major axis of the tubes 101 , 108 . Wedge 109 slidingly engages an inner surface 112 of tube 108 . Piston tapered end 104 engages tapered hole 113 in wedge 109 . Wedge 109 is urged into contact with piston 111 by spring 107 . Biasing member or spring 107 bears upon cap 110 and wedge 109 . Cap 110 may be affixed to a mounting surface, such as on a tensioner body as described in FIG. 1 .

[0054] In operation, cap 105 moves in direction C during a compression stroke. It moves in direction R during a return stroke. The detailed description of operation is set forth in FIG. 7 ( a ) and FIG. 7 ( b ). Further, during the compression stroke, the wedge 109 is pushed in direction C, thereby causing behavior as described in FIG. 7 ( b ) for the return stroke. The damping force in is increased during the return stroke in direction R since the inner surface 112 is moving in a manner so as to press wedge 109 into the tapered end 119 of piston 104 . This is described in FIG. 7 ( a ). One skilled in the art will appreciate that the mechanism described in this FIG. 8 depicts a damping mechanism that is operable in various applications including a belt tensioner with a pulley.

[0055] FIG. 9 is a detail of the wedge in FIG. 8 . Wedge 109 comprises splines or pleats 114 . Splines 114 cooperatively engage a like shape on the inner surface 112 of tube 101 as shown in FIG. 10 . Wedge 109 may have radially extending slots 115 that facilitate expansion of the wedge against the inner surface 112 . Wedge splines 114 may comprise a nonmetallic material, such as plastic or phenolic.

[0056] FIG. 10 is an end view of the outer tube. Tube 101 comprises inner surface 112 . Surface 112 describes a pleated or splined profile that cooperatively engages splines 114 on wedge 104 . Surface 112 and splines 114 each comprise materials that create a desired frictional coefficient. For example, the splines 114 may comprise a plastic, phenolic or non-metallic material while surface may comprise like materials. The preferred embodiment comprises a non-metallic material on splines 114 and a metallic material on surface 112 , as well as surface 112 ( FIG. 10 ), surface 212 ( FIG. 11, 18 ), surface 312 ( FIG. 20 ).

[0057] FIG. 11 is a cross-sectional view of a second alternate embodiment of the invention. In this alternate embodiment, spring 202 is contained within tube 201 . Damper 200 comprises a cylinder slidingly engaged within another cylinder. Outer tube 201 slidingly engages tube 208 . Cap 205 is attached to tube 208 . Cap 210 is attached to tube 201 . Biasing member or spring 202 extends between tube 208 and cap 210 , thereby urging them apart. Plastic liner 206 facilitates sliding movement between outer tube 201 and tube 208 . One end of piston 211 is affixed to cap 210 and is parallel to a major axis of the tubes 201 , 208 . Wedge 209 slidingly engages an inner surface 212 of tube 208 . Piston tapered end 204 engages tapered hole 213 in wedge 209 . Wedge 209 is urged against tapered end 204 by compressible member or spring 207 . Spring 207 bears upon cap 210 and wedge 209 . Cap 210 is affixed to a mounting surface, such as on a tensioner body as described in FIG. 1 . One skilled in the art will appreciate that the mechanism described in this FIG. 11 depicts a damping mechanism that is operable on other applications including a tensioner with a pulley.

[0058] In operation, cap 205 moves in direction C during a compression stroke. Cap 205 moves in direction R during a return stroke. The detailed description of operation is set forth in FIGS. 7 ( a ), 7 ( b ) and FIG. 8 .

[0059] FIG. 12 depicts another alternate embodiment of the damper 300 . The elements are generally as described in FIG. 11 with the following differences; washer, ring or bearing surface 308 is affixed to piston 211 at a pre-determined point. Bearing surface 308 extends normally to the piston axis D. Compressible member or spring 307 bears on the bearing surface 308 . The other end of spring 307 bears on camming body or wedge 309 . Wedge 309 is of substantially the same form as wedge 209 in FIG. 11 . One skilled in the art will appreciate that the mechanism described in this FIG. 12 depicts a damping mechanism that is operable on other applications including a tensioner with a pulley.

[0060] Reference to FIG. 11 and FIG. 12 also illustrates the change in length L ₁ and L ₂ as the invention operates. Lengths increase during the return stroke R (L ₂ ) and decrease during the compression stroke C (L ₁ ).

[0061] FIG. 13 is a cross-sectional view along axis A-A of yet another alternate embodiment of the invention. First housing or cap 405 comprises first housing surface or side 408 . Second housing or tube 401 further comprises outer surface 412 . Side 408 describes a conical form having an angle α to the major axis A in the range of 0° to 30°. Side 408 may have any form required by a user, including pleated. Wedge 409 slides between side 408 and outer surface 412 . Spring 402 urges wedge 409 into contact with side 408 and outer surface 412 . As wedge 409 is urged against surface 412 , it is radially compressed. Radial compression of wedge 409 occurs due to the presence of the slots as described in FIG. 2 and FIG. 21 . Spring 402 bears on base 410 , which is affixed to tube 410 . Cap 405 moves in direction C during a compression stroke and in direction R during a return stroke. A load L may be applied to the device at bearing point 418 . One skilled in the art will appreciate that the mechanism described in this FIG. 13 depicts a damping mechanism that is operable on other applications including a tensioner with a pulley.

[0062] FIG. 14 is a cross-sectional view along axis A-A of yet another alternate embodiment of the invention. First housing or tube 501 comprises first housing surface or side 508 and end 510 . Side 508 describes a conical form having an angle β to the major axis A in the range of 0° to 30°. Side 508 may have any profile required by a user including pleated. Wedge 509 slides between first housing surface or side 508 and outer surface 516 of piston 514 . Wedge 509 has the same form as shown in FIG. 21 for wedge 409 . Body 519 and surfaces 516 have the same form as shown in FIG. 21 for surface 412 . Spring 502 bears on end 510 and piston 514 . Spring 502 resists an axial movement of piston 514 . Compressible member or spring 502 also bears on base 510 against piston 514 . Compressible member or spring 507 urges wedge 509 into contact with side 508 and outer surface 516 of piston 514 . As wedge 509 is urged against surface 516 , it is radially compressed. Radial compression of wedge 509 occurs due to the presence of the slots as described in FIG. 2 and FIG. 21 . Piston 514 moves in direction C during a compression stroke and in direction R during a return stroke. An axial load L may be applied to the device at bearing point 518 . One skilled in the art will appreciate that the mechanism described in FIG. 14 depicts a damping mechanism that is operable on other applications including a tensioner with a pulley.

[0063] FIG. 15 is a plan view of a tensioner damper assembly. Damper 600 as described in the foregoing FIGS. 8 , 11 - 14 is shown connected to an idler pulley 610 by shaft 620 . Shaft 620 may be connected to a base (not shown) that connects the idler to tracks 615 . Idler 610 slides along parallel tracks 615 . Belt B is trained about idler 610 .

[0064] FIG. 16 is a perspective exploded view of the damping mechanism for an alternate embodiment. FIG. 16 generally describes the arrangement of the damping mechanism for the embodiments depicted in FIGS. 8, 11 and 12 . The numbers in FIG. 16 relate to FIG. 8 . Surfaces 114 slidingly engage surfaces 112 . Tapered end 104 engages hole 113 . Slots 115 allow wedge 109 to radially expand as tapered end 104 moves axially into wedge 109 . Wedge 109 may comprise a nonmetallic material, such as plastic or phenolic.

[0065] FIG. 17 is an end plan view of the wedge for an alternate embodiment. The alternate embodiment is depicted in FIG. 11 . Wedge splines 214 may comprise a nonmetallic material, such as plastic or phenolic.

[0066] FIG. 18 is an end plan view of the tube of an alternate embodiment. The alternate embodiment is depicted in FIG. 11 .

[0067] FIG. 19 is an end plan view of the wedge for an alternate embodiment. The alternate embodiment is depicted in FIG. 12 . Wedge splines 314 may comprise a nonmetallic material, such as plastic or phenolic.

[0068] FIG. 20 is an end plan view of the tube of an alternate embodiment. The alternate embodiment is depicted in FIG. 12 .

[0069] FIG. 21 is an exploded view of the wedge and tube for an alternate embodiment. The embodiment is depicted in FIG. 13 . FIG. 21 also generally depicts the arrangement of the wedge 509 and the piston surfaces 516 for the embodiment depicted in FIG. 14 . Slots 415 allow wedge 409 to radially compress against surfaces 412 . Wedge 409 may comprise a nonmetallic material, such as plastic or phenolic.

[0070] Although a single form of the invention has been described herein, it will be obvious to those skilled in the art that variations may be made in the construction and relation of parts without departing from the spirit and scope of the invention described herein.