U.S. patent application number 09/972173 was filed with the patent office on 2002-02-28 for tensioner.
Invention is credited to Dec, Andrzej, Hanes, David, Serkh, Alexander.
Application Number | 20020025869 09/972173 |
Document ID | / |
Family ID | 24192256 |
Filed Date | 2002-02-28 |
United States Patent
Application |
20020025869 |
Kind Code |
A1 |
Serkh, Alexander ; et
al. |
February 28, 2002 |
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.
Inventors: |
Serkh, Alexander; (Troy,
MI) ; Dec, Andrzej; (Rochester Hills, MI) ;
Hanes, David; (Troy, MI) |
Correspondence
Address: |
THE GATES CORPORATION
900 S. BROADWAY
DENVER
CO
80209
US
|
Family ID: |
24192256 |
Appl. No.: |
09/972173 |
Filed: |
October 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09972173 |
Oct 5, 2001 |
|
|
|
09549258 |
Apr 14, 2000 |
|
|
|
Current U.S.
Class: |
474/135 ;
474/101; 474/133; 474/138 |
Current CPC
Class: |
F16F 7/08 20130101; F16H
2007/084 20130101; F16H 7/0831 20130101; F16H 7/1218 20130101; F16H
2007/0806 20130101; F16H 2007/0893 20130101; F16H 2007/0851
20130101 |
Class at
Publication: |
474/135 ;
474/138; 474/101; 474/133 |
International
Class: |
F16H 007/08; F16H
007/22; F16H 007/12 |
Claims
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.degree.to 30.degree..
47. The damper as in claim 39, wherein the first housing surface
describes a conical shape having an angle in the range of
0.degree.to 30.degree..
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.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This divisional application claims priority from U.S.
non-provisional application Ser. No. 09/549,258.
FIELD OF THE INVENTION
[0002] The invention relates to tensioners, more particularly to
tensioners that are spring biased, wedge actuated belt tensioning
devices having damping and used with belts for vehicle accessory
drives.
BACKGROUND OF THE INVENTION
[0003] Most engines used for automobiles and the like include a
number of belt driven accessory systems which are necessary for the
proper operation of the vehicle. The accessory systems may include
an alternator, air conditioner compressor and a power steering
pump.
[0004] The accessory systems are generally mounted on a front
surface of the engine. Each accessory would have a pulley mounted
on a shaft for receiving power from some form of belt drive. In
early systems, each accessory was driven by a separate belt that
ran between the accessory and the crankshaft. With improvements in
belt technology, single serpentine belts are now used in most
applications. Accessories are driven by a single serpentine belt
routed among the various accessory components. The serpentine belt
is driven by the engine crankshaft.
[0005] Since the serpentine belt must be routed to all accessories,
it has generally become longer than its predecessors. To operate
properly, the belt is installed with a pre-determined tension. As
it operates, it stretches slightly. This results in a decrease in
belt tension, which may cause the belt to slip. Consequently, a
belt tensioner is used to maintain the proper belt tension as the
belt stretches during use.
[0006] As a belt tensioner operates, the running belt may excite
oscillations in the tensioner spring. These oscillations are
undesirable, as they cause premature wear of the belt and
tensioner. Therefore, a damping mechanism is added to the tensioner
to damp the oscillations.
[0007] Various damping mechanisms have been developed. They include
viscous fluid based dampers, mechanisms based on frictional
surfaces sliding or interaction with each other, and dampers using
a series of interacting springs.
[0008] Representative of the art is U.S. Pat. No. 4,402,677(1983)
to Radocaj which discloses a tensioner having an L-shaped housing.
A pair of cam plates having camming surfaces are slideably mounted
in the L-shaped housing. A compression spring biases the camming
plates into sliding engagement with each other. The included angle
of the camming surfaces equal 90.degree. with the angle of a first
camming surface being greater than the angle of a second camming
surface.
[0009] Also representative of the art is U.S. Pat. No.
5,951,423(1999) to Simpson which discloses a mechanical friction
tensioner having spring loaded wedge-shaped blocks and friction
damping. The tensioner has a wedge-shaped piston that interacts
with spring biased wedge-shaped blocks. As the piston moves inward
the wedge-shaped blocks are pushed outward to provide friction
damping.
[0010] The prior art devices rely on springs or other components,
each oriented on axes that are set at a pre-determined angle to
each other. They also rely on a plurality of springs to properly
operate the damping components and to urge the belt pulley into
contact with a belt. The prior art does not teach a damping
components that operate coaxially. Further, the prior art does not
teach use of an expandable camming body. Nor does it teach the use
of an expandable camming body that expands radially. Nor does it
teach the use of an expandable camming body that expands radially
in response to movement against a piston. Nor does it teach the use
of an expandable camming body that expands radially in response to
movement against a tapered piston.
[0011] What is needed is a tensioner having a coaxial piston and
camming body operating coaxially. What is needed is a tensioner
having an expandable camming body. What is needed is a tensioner
having an expandable camming body that is radially expandable. What
is needed is a tensioner having an expandable camming body that is
radially expandable in response to movement against a piston. What
is needed is a tensioner having an expandable camming body that
expands radially in response to movement against a tapered piston.
The present invention meets these needs.
SUMMARY OF THE INVENTION
[0012] The primary aspect of the invention is to provide a
tensioner having a coaxial tapered piston and camming body.
[0013] Another aspect of the invention is to provide a tensioner
having an expandable camming body.
[0014] Another aspect of the invention is to provide a tensioner
having an expandable camming body that is radially expandable.
[0015] Another aspect of the invention is to provide a tensioner
having an expandable camming body that is radially expandable in
response to movement against a piston.
[0016] Another aspect of the invention is to provide a linear
tensioner having an expandable camming body that expands radially
in response to movement against a tapered piston.
[0017] Other aspects of the invention will be pointed out or made
obvious by the following description of the invention and the
accompanying drawings.
[0018] The invention comprises a self-contained mechanical belt
tensioner that produces damping which is a function of applied
hubload through the effect of frictional forces derived from the
sliding action of mutually opposing wedges. A conical piston is
contained within a housing. The conical piston cooperates with a
conical wedge or camming body. The conical wedge slides on the
inner surface of the housing. The conical wedge is radially
expandable in a direction normal to 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 radially 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 wedge and conical
piston. The greater the impulse, then the greater the expansion of
the conical wedge. Hence, this increases the resultant frictional
force resisting movement between the conical wedge and the housing.
As the load moves toward a minimum, the camming body radially
contracts and the frictional force is abated to a low level
allowing ease of retraction of the piston.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The accompanying drawings, which are incorporated in and
form a part of the specification, illustrate preferred embodiments
of the present invention, and together with a description, serve to
explain the principles of the invention.
[0020] FIG. 1 is a cross-sectional view of the invention.
[0021] FIG. 2(a) is a top plan view of the wedge through section
2a-2a in FIG. 3.
[0022] FIG. 2(b) is a side elevation view of the wedge through
section 2b-2b in FIG. 3.
[0023] FIG. 3 is a side cross-section view of the damping section
of the invention:
[0024] FIG. 4 is a perspective view of the wedge.
[0025] FIG. 5 is a perspective view of the piston 14.
[0026] FIG. 6 is a perspective view of the housing 1.
[0027] FIG. 7(a) is a schematic free body diagram of the damping
mechanism during a compression stroke.
[0028] FIG. 7(b) is a schematic free body diagram of the damping
mechanism during a return stroke.
[0029] FIG. 8 is a cross-sectional view of a first alternate
embodiment of the invention.
[0030] FIG. 9 is a plan view of the wedge for the alternate
embodiment.
[0031] FIG. 10 is a cross-sectional view of the housing for the
alternate embodiment:
[0032] FIG. 11 is a cross-sectional view of a second alternate
embodiment of the invention.
[0033] FIG. 12 is a cross-sectional view of a third alternate
embodiment of the invention.
[0034] FIG. 13 is a cross-sectional view along axis A-A of a fourth
alternate embodiment of the invention.
[0035] FIG. 14 is a cross-sectional view along axis A-A of a fifth
alternate embodiment of the invention.
[0036] FIG. 15 is a plan view of a tensioner.
[0037] FIG. 16 is a perspective exploded view of the damping
mechanism for an alternate embodiment.
[0038] FIG. 17 is an end plan view of the wedge for an alternate
embodiment.
[0039] FIG. 18 is an end plan view of the tube of an alternate
embodiment.
[0040] FIG. 19 is an end plan view of the wedge for an alternate
embodiment.
[0041] FIG. 20 is an end plan view of the tube of an alternate
embodiment.
[0042] FIG. 21 is an exploded view of the wedge and tube for an
alternate embodiment.
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
2a-2a 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. 2a, 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 2b-2b 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.sub.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.sub.1C and N.sub.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
.mu.N.sub.1C and .mu.N.sub.2C. This force is additive with the
spring force, F.sub.s, as each acts in the same direction. As the
hubload increases, so increases HC. An increase in HC increases
N.sub.1C and N.sub.2C until wedge 13 starts moving, which in turn
increases the friction forces .mu.N.sub.1C and .mu.N.sub.2C
resisting movement of the wedge in the housing. It should be noted
that there is no further substantive increase in N.sub.1C and
N.sub.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.sub.s minus friction .mu.N.sub.1R, the wedge will be
pushed in direction B. The normal forces, N.sub.1R and N.sub.2R are
less than N.sub.1C and N.sub.2C. Further, the friction force vector
is in the opposite direction as compared to the compression stroke,
.mu.N.sub.1R and .mu.N.sub.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.sub.1 and L.sub.2 as the invention operates. Lengths
increase during the return stroke R (L.sub.2) and decrease during
the compression stroke C (L.sub.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 .alpha. to the major axis A in the
range of 0.degree. to 30.degree.. 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 .beta. to the
major axis A in the range of 0.degree. to 30.degree.. 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.
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